CN111866758B - Communication method, device, medium and electronic equipment for multicast broadcast service - Google Patents

Abstract

The embodiment of the application provides a communication method, a communication device, a communication medium and electronic equipment for multicast broadcast services. The method comprises the following steps: receiving a first MBS conversation starting request sent by an i-th level control surface node in an MBS conversation transmission tree; selecting a first user plane node and a second user plane node, respectively sending user plane MBS session establishment requests to the first user plane node and the second user plane node, and receiving user plane MBS session establishment responses fed back by the first user plane node and the second user plane node; and sending a second MBS conversation starting request to a sub control surface node provided by the ith level control surface node to indicate the sub control surface node to allocate a sub user surface node for the second user surface node, wherein the second MBS conversation starting request comprises a third MBS IP multicast transmission address and a third C-TEID allocated by the second user surface node. The technical scheme of the embodiment of the application can realize the establishment of the user plane MBS session transmission tree under the communication system architecture with the separation of the control plane and the user plane.

Description

Communication method, device, medium and electronic equipment for multicast broadcast service

Technical Field

The present application relates to the field of computer and communication technologies, and in particular, to a communication method, an apparatus, a medium, and an electronic device for multicast broadcast services.

Background

In a 5G MBS (Multicast and Broadcast Service) system, a control plane is separated from a user plane, that is, a control plane node and a user plane node are no longer the same network node, and in this case, establishing a user plane MBS session transmission tree will face various problems.

Disclosure of Invention

Embodiments of the present application provide a communication method, an apparatus, a medium, and an electronic device for multicast broadcast services, so that establishment of a user plane MBS session transmission tree can be implemented at least to a certain extent in a communication system architecture in which a control plane is separated from a user plane, and transmission efficiency of MBS service data can also be improved.

Other features and advantages of the present application will be apparent from the following detailed description, or may be learned by practice of the application.

According to an aspect of an embodiment of the present application, there is provided a communication method for a multicast broadcast service, the method including: receiving a first MBS session start request sent by an i-th level control plane node in an MBS session transmission tree, where the first MBS session start request includes information of a sub-control plane node provided by the i-th level control plane node, identification information of the i-th level user plane node selected by the i-th level control plane node, a first MBS IP multicast transmission address allocated by the i-th level user plane node, and a first C-TEID (Common Tunnel Endpoint Identifier) for transmitting MBS service data in a multicast manner; selecting a first user plane node capable of establishing connection with the ith level user plane node and a second user plane node capable of establishing connection with both the first user plane node and a user plane functional entity managed by the sub control plane node according to the information of the ith level control plane node and the information of the sub control plane node provided by the ith level control plane node; sending a first user plane MBS session establishment request to the first user plane node, and receiving a first user plane MBS session establishment response fed back by the first user plane node, wherein the first user plane MBS session establishment request comprises a first MBS IP multicast transmission address and a first C-TEID, and the first MBS IP multicast transmission address is used for enabling the first user plane node to join a multicast transmission group corresponding to the first MBS IP multicast transmission address to receive MBS service data sent by the i-level user plane node in a multicast mode; sending a second user plane MBS session establishment request to the second user plane node, and receiving a second user plane MBS session establishment response fed back by the second user plane node, wherein the second user plane MBS session establishment request comprises a second MBS IP multicast transmission address and a second C-TEID which are distributed by the first user plane node, and the second MBS IP multicast transmission address is used for enabling the second user plane node to join a multicast transmission group corresponding to the second MBS IP multicast transmission address to receive MBS service data sent by the first user plane node in a multicast mode; sending a second MBS session starting request to a sub-control surface node provided by the ith level control surface node to indicate the sub-control surface node provided by the ith level control surface node to allocate a sub-user surface node to the second user surface node, wherein the second MBS session starting request comprises a third MBS IP multicast transmission address and a third C-TEID which are allocated by the second user surface node, and the third MBS IP multicast transmission address is used for enabling the sub-user surface node to join a multicast transmission group corresponding to the third MBS IP multicast transmission address to receive MBS service data sent by the second user surface node in a multicast mode.

According to an aspect of an embodiment of the present application, there is provided a communication method for a multicast broadcast service, the method including: sending a second user plane MBS session establishment request to an ith user plane node selected by an ith control plane node, and receiving a second user plane MBS session establishment response fed back by the ith user plane node, wherein the ith control plane node is any level of control plane node except the last level of control plane node in an MBS session transmission tree; selecting an I-SMF (Intermediate-Session Management Function entity), and sending a first MBS Session start request to the I-SMF, wherein the first MBS Session start request comprises information of a sub control surface node provided by the ith level control surface node, identification information of the ith level user surface node, a first MBS IP multicast transmission address distributed by the ith level user surface node and a first C-TEID; the first MBS session start request is used to trigger the I-SMF to select a first user plane node capable of establishing a connection with the I-level user plane node, and a second user plane node capable of establishing a connection with both the first user plane node and a user plane functional entity managed by the sub-control plane node, and to trigger the I-SMF to send a second MBS session start request to the sub-control plane node, where the first user plane node is used to join a multicast transmission group corresponding to the first MBS IP multicast transmission address to receive MBS service data sent by the I-level user plane node in a multicast manner, the second user plane node is used to join a multicast transmission group corresponding to a second MBS IP transmission address allocated by the first user plane node to receive MBS service data sent by the first user plane node in a multicast manner, and the second MBS session start request is used to instruct the sub-control plane node to allocate a sub-user plane node to the second user plane node, and enable the sub-user plane node to receive the MBS service data sent by the first user plane node.

According to an aspect of an embodiment of the present application, a communication method for multicast broadcast service is provided, where the method includes: receiving a first user plane MBS session establishment request sent by an I-SMF, wherein the first user plane MBS session establishment request comprises a first MBS IP multicast transmission address and a first C-TEID which are distributed by an I-level user plane node; feeding back a first user plane MBS session establishment response to the I-SMF, wherein the first user plane MBS session establishment response comprises a second MBS IP multicast transmission address and a second C-TEID which are distributed by a first user plane node selected by the I-SMF, and the second MBS IP multicast transmission address is used for enabling a second user plane node selected by the I-SMF to join a multicast transmission group corresponding to the second MBS IP multicast transmission address to receive MBS service data transmitted by the first user plane node in a multicast mode; and if the first user plane node supports receiving the MBS service data sent by the ith user plane node in a multicast mode, adding a multicast transmission group corresponding to the first MBS IP multicast transmission address to receive the MBS service data sent by the ith user plane node in a multicast mode.

According to an aspect of an embodiment of the present application, a communication method for multicast broadcast service is provided, where the method includes: receiving a second user plane MBS session establishment request sent by the I-SMF, wherein the second user plane MBS session establishment request comprises a second MBS IP multicast transmission address and a second C-TEID which are distributed by the first user plane node selected by the I-SMF; feeding back a second user plane MBS session establishment response to the I-SMF, wherein the second user plane MBS session establishment response comprises a third MBS IP multicast transmission address and a third C-TEID which are distributed by a second user plane node selected by the I-SMF, and the third MBS IP multicast transmission address is used for a sub-user plane node of the second user plane node to join a multicast transmission group corresponding to the third MBS IP multicast transmission address to receive MBS service data transmitted by the second user plane node in a multicast mode; and if the second user plane node supports receiving the MBS service data sent by the first user plane node in a multicast mode, adding a multicast transmission group corresponding to the second MBS IP multicast transmission address to receive the MBS service data sent by the first user plane node in the multicast mode.

According to an aspect of an embodiment of the present application, there is provided a communication apparatus for multicast broadcast service, including: a first receiving unit, configured to receive a first MBS session start request sent by an i-th level control plane node in an MBS session transmission tree, where the first MBS session start request includes information of a sub-control plane node provided by the i-th level control plane node, identification information of an i-th level user plane node selected by the i-th level control plane node, a first MBS IP multicast transmission address allocated by the i-th level user plane node, and a first C-TEID used for transmitting MBS service data in a multicast manner; a selecting unit, configured to select, according to the information of the ith-level control plane node and the information of the sub-control plane node provided by the ith-level control plane node, a first user plane node capable of establishing a connection with the ith-level user plane node, and a second user plane node capable of establishing a connection with both the first user plane node and a user plane functional entity managed by the sub-control plane node; a first interaction unit, configured to send a first user plane MBS session establishment request to the first user plane node, and receive a first user plane MBS session establishment response fed back by the first user plane node, where the first user plane MBS session establishment request includes the first MBS IP multicast transport address and a first C-TEID, and the first MBS IP multicast transport address is used to enable the first user plane node to join a multicast transport group corresponding to the first MBS IP multicast transport address to receive MBS service data sent by the i-th level user plane node in a multicast manner; a second interaction unit, configured to send a second user plane MBS session establishment request to the second user plane node, and receive a second user plane MBS session establishment response fed back by the second user plane node, where the second user plane MBS session establishment request includes a second MBS IP multicast transmission address and a second C-TEID allocated by the first user plane node, and the second MBS IP multicast transmission address is used to enable the second user plane node to join a multicast transmission group corresponding to the second MBS IP multicast transmission address to receive MBS service data sent by the first user plane node in a multicast manner; a third interaction unit, configured to send a second MBS session start request to the sub-control plane node provided by the ith-level control plane node, so as to indicate the sub-control plane node provided by the ith-level control plane node to allocate a sub-user plane node to the second user plane node, where the second MBS session start request includes a third MBS IP multicast transport address and a third C-TEID allocated by the second user plane node, and the third MBS IP multicast transport address is used to enable the sub-user plane node to join a multicast transport group corresponding to the third MBS IP multicast transport address to receive MBS service data sent by the second user plane node in a multicast manner.

In some embodiments of the present application, based on the foregoing scheme, the first user plane MBS session establishment request includes indication information for indicating the first user plane node to allocate new MBS IP multicast distribution information; the first user plane MBS session establishment response comprises the second MBS IP multicast transmission address and the second C-TEID which are distributed by the first user plane node.

In some embodiments of the present application, based on the foregoing scheme, if the first user plane node does not support receiving MBS service data of the i-level user plane node in a multicast manner but in a point-to-point manner, the first user plane MBS session establishment request includes indication information requesting that an F-TEID (full qualified Tunnel Endpoint Identifier) is allocated to the first user plane node, and the first user plane MBS session establishment response includes the F-TEID allocated to the first user plane node, where the F-TEID allocated to the first user plane node is used to enable the first user plane node to receive the MBS service data sent by the i-level user plane node in a point-to-point manner; or

The first user plane MBS conversation establishing response indicates that the first user plane node does not support the MBS service data of the i-level user plane node by a multicast mode but a point-to-point mode, and the MBS service data comprises the F-TEID distributed by the first user plane node.

In some embodiments of the present application, based on the foregoing scheme, if the second user plane node does not support receiving MBS service data of the first user plane node in a multicast manner but in a point-to-point manner, the second user plane MBS session establishment request includes indication information requesting to allocate F-TEIDs to the second user plane node, the second user plane MBS session establishment response includes F-TEIDs allocated to the second user plane node, and the F-TEIDs allocated to the second user plane node are used to enable the second user plane node to receive MBS service data sent by the first user plane node in a point-to-point manner; or

And the second user plane MBS conversation establishment response indicates that the second user plane node does not support the MBS service data sent by the first user plane node in a multicast mode but in a point-to-point mode, and the second user plane MBS conversation establishment response comprises the F-TEID distributed by the second user plane node.

In some embodiments of the present application, based on the foregoing solution, the first interaction unit is further configured to: after the second interaction unit receives a second user plane MBS session establishment response fed back by the second user plane node, if a second user plane node does not support receiving MBS service data sent by the first user plane node in a multicast mode but in a point-to-point mode exists, sending a first user plane MBS session modification request to the first user plane node, wherein the first user plane MBS session modification request comprises F-TEID distributed by the second user plane node which does not support receiving the MBS service data sent by the first user plane node in a multicast mode, so that the first user plane node transmits the MBS service data to the second user plane node which does not support receiving the MBS service data sent by the first user plane node in a point-to-point mode;

If a second user plane node supporting receiving of the MBS service data sent by the first user plane node in a multicast mode exists at the same time, the first user plane MBS session modification request further includes a field for starting multicast mode transmission to indicate that the first user plane node sends the MBS service data to the second user plane node in a multicast transmission mode at the same time.

In some embodiments of the present application, based on the foregoing solution, the third interaction unit is further configured to: after sending a second MBS conversation starting request to a sub control surface node provided by the ith level control surface node, receiving a second MBS conversation starting response fed back by the sub control surface node aiming at the second MBS conversation starting request, wherein the second MBS conversation starting response comprises first indication information;

the first indication information includes identification information of the second user plane node, first F-TEID list information and first field information for indicating that multicast mode transmission is started, where the first field information indicates that there is a sub-user plane node supporting receiving, in the sub-user plane nodes allocated by the sub-control plane node to the second user plane node, MBS service data sent by the second user plane node in a multicast mode, and the first F-TEID list information includes F-TEIDs of sub-user plane nodes that do not support receiving, in a multicast mode, MBS service data sent by the second user plane node in a point-to-point mode; or

The first indication information includes identification information of the second user plane node, and does not include the first F-TEID list information and the first field information, and the first indication information is used to indicate that all the sub-user plane nodes allocated by the sub-control plane node to the second user plane node support receiving MBS service data sent by the second user plane node in a multicast manner; or

The first indication information includes identification information of the second user plane node, the first F-TEID list information, and does not include the first field information, and the first indication information is used to indicate that none of the sub-user plane nodes allocated by the sub-control plane node to the second user plane node support receiving MBS service data sent by the second user plane node in a multicast manner but in a point-to-point manner; or

The first indication information includes identification information of the second user plane node and field information for disabling multicast transmission, and does not include the first F-TEID list information, and the first indication information is used to indicate that the child control plane node does not assign a child user plane node to the second user plane node.

In some embodiments of the present application, based on the foregoing scheme, if at least two second user plane nodes are selected, the second MBS session start response includes a first indication information list, where the first indication information list includes the first indication information corresponding to all the second user plane nodes respectively.

In some embodiments of the present application, based on the foregoing solution, the second MBS session start response further includes a failed identification information list, where the failed identification information list is used to indicate a target second user plane node to which a sub-user plane node is not allocated.

In some embodiments of the present application, based on the foregoing solution, the second interaction unit is further configured to: and if the target second user plane node which is not allocated with the sub-user plane node is determined to exist according to the second MBS conversation starting response, sending a user plane MBS conversation deleting request to the target second user plane node.

In some embodiments of the present application, based on the foregoing solution, the second interaction unit is further configured to: and receiving a user plane MBS session deletion response fed back by the target second user plane node, wherein the user plane MBS session deletion response is sent by the target second user plane node after receiving the user plane MBS session deletion request, and if the target second user plane node is added into the multicast transmission group corresponding to the second MBS IP multicast transmission address, the user plane MBS session deletion response exits the multicast transmission group corresponding to the second MBS IP multicast transmission address after receiving the user plane MBS session deletion request.

In some embodiments of the present application, based on the foregoing solution, the second interaction unit is configured to: if the ith level control plane node provides at least two sub-control plane nodes, after receiving second MBS session start responses respectively fed back by all the sub-control plane nodes of the ith level control plane node, determining whether a target second user plane node which is not allocated with the sub-user plane node exists.

In some embodiments of the present application, based on the foregoing solution, the second interaction unit is further configured to: after receiving a second MBS session start response fed back by the sub-control plane node aiming at the second MBS session start request, if the first indication information contains the first F-TEID list information, sending a second user plane MBS session modification request to the second user plane node according to the identification information of the second user plane node contained in the first indication information, so as to indicate the second user plane node to respectively transmit MBS service data to the sub-user plane nodes corresponding to each F-TEID contained in the first F-TEID list information in a point-to-point manner;

wherein, if the first indication information further includes the first field information, the second user plane MBS session modification request is further used to indicate that the second user plane node simultaneously uses a multicast transmission mode to send MBS service data to a sub-user plane node of the second user plane node;

If the first indication information does not contain the first field information, the second user plane MBS session modification request is also used for indicating that the second user plane node does not need to use a multicast transmission mode to send MBS service data to the sub user plane nodes of the second user plane node.

In some embodiments of the present application, based on the foregoing solution, the second interaction unit is configured to: and if at least two second user plane nodes are selected, sending the second user plane MBS session modification request to an intermediate user plane node needing to send the second user plane MBS session modification request according to the first indication information corresponding to each second user plane node contained in the second MBS session starting response.

In some embodiments of the present application, based on the foregoing solution, the third interaction unit is further configured to: after receiving a second MBS session starting response fed back by the sub control surface node aiming at the second MBS session starting request, feeding back a first MBS session starting response aiming at the first MBS session starting request to the i-th level control surface node according to the second MBS session starting response fed back by the sub control surface node.

In some embodiments of the present application, based on the foregoing solution, the third interaction unit is configured to: if the i-th level control surface node provides at least two sub control surface nodes, after receiving second MBS session start responses respectively fed back by all the sub control surface nodes of the i-th level control surface node, feeding back the first MBS session start response to the i-th level control surface node.

In some embodiments of the present application, based on the foregoing scheme, the first MBS session start response includes second indication information;

the second indication information comprises identification information of the ith user plane node, second F-TEID list information and second field information used for indicating that multicast mode transmission is started, the second field information indicates that a first user plane node supporting receiving of MBS service data sent by the ith user plane node in a multicast mode exists, and the second F-TEID list information comprises F-TEID of the first user plane node not supporting receiving of MBS service data sent by the ith user plane node in a point-to-point mode; or

The second indication information includes the identification information of the ith-level user plane node and does not include the second F-TEID list information and the second field information, and the second indication information is used to indicate that the first user plane node supports receiving MBS service data sent by the ith-level user plane node in a multicast manner; or

The second indication information includes the identification information of the i-th user plane node, the second F-TEID list information, and does not include the second field information, and the second indication information is used to indicate that the first user plane node does not support receiving MBS service data sent by the i-th user plane node in a multicast manner but in a point-to-point manner.

In some embodiments of the present application, based on the foregoing scheme, if the ith-level control plane node selects at least two ith-level user plane nodes, the first MBS session start response includes a second indication information list, where the second indication information list includes the second indication information corresponding to all ith-level user plane nodes respectively.

In some embodiments of the present application, based on the foregoing solution, the second interaction unit is configured to: under the condition that at least two first user plane nodes and at least two second user plane nodes are selected, respectively sending a second user plane MBS conversation establishing request to each selected second user plane node, wherein the second user plane MBS conversation establishing request sent to each second user plane node comprises a second MBS IP multicast transmission address and a second C-TEID which are distributed by the corresponding first user plane node; wherein, the second MBS IP multicast transmission addresses distributed by different first user plane nodes are different.

In some embodiments of the present application, based on the foregoing scheme, if the ith control plane node selects at least two ith user plane nodes, the first MBS session start request includes the identification information of each ith user plane node, and the first MBS IP multicast transmission address and the first C-TEID allocated to each ith user plane node; wherein, the first MBS IP multicast transmission addresses distributed by different i-th level user plane nodes are different.

According to an aspect of an embodiment of the present application, there is provided a communication apparatus for multicast broadcast service, including: a fourth interaction unit, configured to send a second user plane MBS session establishment request to an i-th level user plane node selected by an i-th level control plane node, and receive a second user plane MBS session establishment response fed back by the i-th level user plane node, where the i-th level control plane node is any level of control plane node except for a last level of control plane node in an MBS session transmission tree; a fifth interaction unit, configured to select an intermediate session management function entity I-SMF, and send a first MBS session start request to the I-SMF, where the first MBS session start request includes information of a sub-control plane node provided by the I-th level control plane node, identification information of the I-th level user plane node, a first MBS IP multicast transport address and a first C-TEID allocated by the I-th level user plane node; the first MBS session start request is used to trigger the I-SMF to select a first user plane node capable of establishing a connection with the I-level user plane node, and a second user plane node capable of establishing a connection with both the first user plane node and a user plane functional entity managed by the sub-control plane node, and to trigger the I-SMF to send a second MBS session start request to the sub-control plane node, where the first user plane node is used to join a multicast transmission group corresponding to the first MBS IP multicast transmission address to receive MBS service data sent by the I-level user plane node in a multicast manner, the second user plane node is used to join a multicast transmission group corresponding to a second MBS IP transmission address allocated by the first user plane node to receive MBS service data sent by the first user plane node in a multicast manner, and the second MBS session start request is used to instruct the sub-control plane node to allocate a sub-user plane node to the second user plane node, and enable the sub-user plane node to receive the MBS service data sent by the first user plane node.

In some embodiments of the present application, based on the foregoing solution, the fifth interaction unit is further configured to: after sending a first MBS session start request to the I-SMF, receiving a first MBS session start response fed back by the I-SMF for the first MBS session start request; and determining whether to send a user plane MBS session modification request to the i-level user plane node or not according to the content contained in the first MBS session starting response.

In some embodiments of the present application, based on the foregoing solution, the fifth interaction unit is configured to: and if it is determined that the user plane functional entity managed by the ith control plane node cannot directly establish a transmission path with the user plane functional entity managed by the sub control plane node according to the information of the sub control plane node provided by the ith control plane node, selecting an SMF capable of communicating with the ith control plane node and the sub control plane node as the I-SMF.

According to an aspect of an embodiment of the present application, there is provided a communication apparatus for multicast broadcast service, including: the second receiving unit is configured to receive a first user plane MBS session establishment request sent by the I-SMF, wherein the first user plane MBS session establishment request comprises a first MBS IP multicast transmission address and a first C-TEID which are distributed by the ith user plane node; a first sending unit, configured to feed back a first user plane MBS session establishment response to the I-SMF, where the first user plane MBS session establishment response includes a second MBS IP multicast transmission address and a second C-TEID allocated by the first user plane node selected by the I-SMF, and the second MBS IP multicast transmission address is used to enable the second user plane node selected by the I-SMF to join a multicast transmission group corresponding to the second MBS IP multicast transmission address to receive MBS service data transmitted by the first user plane node in a multicast manner; a first processing unit, configured to join a multicast transmission group corresponding to the first MBS IP multicast transmission address to receive MBS service data sent by the i-th level user plane node in a multicast manner when the first user plane node supports receiving the MBS service data sent by the i-th level user plane node in a multicast manner.

In some embodiments of the present application, based on the foregoing solution, the first processing unit is further configured to: and if the first user plane node does not support the MBS service data sent by the i-level user plane node in a multicast mode but supports the point-to-point receiving mode, distributing the F-TEID for receiving the MBS service data sent by the i-level user plane node in the point-to-point mode.

In some embodiments of the present application, based on the foregoing scheme, the second receiving unit is further configured to: after the first sending unit feeds back a first user plane MBS session establishment response to the I-SMF, receiving a first user plane MBS session modification request sent by the I-SMF, wherein the first user plane MBS session modification request comprises F-TEID distributed by a second user plane node which does not support receiving MBS service data sent by the first user plane node in a multicast mode;

the first processing unit is further configured to: and based on the F-TEID of a second user plane node which does not support receiving the MBS service data sent by the first user plane node in a multicast mode but in a point-to-point mode, transmitting the MBS service data to the second user plane node which does not support receiving the MBS service data sent by the first user plane node in a multicast mode but in a point-to-point mode, and determining whether to simultaneously use a multicast transmission mode to send the MBS service data to other second user plane nodes according to the first user plane MBS session modification request.

In some embodiments of the present application, based on the foregoing solution, the first sending unit is further configured to: if a user plane MBS session deleting request sent by the I-SMF is received, sending a user plane MBS session deleting response to the I-SMF; and if the user terminal is added into the multicast transmission group corresponding to the first MBS IP multicast transmission address, the user terminal exits from the multicast transmission group corresponding to the first MBS IP multicast transmission address after receiving the user terminal MBS session deleting request.

In some embodiments of the present application, based on the foregoing scheme, the first sending unit is configured to: if receiving a plurality of user plane MBS conversation establishment requests, feeding back a user plane MBS conversation establishment request feedback user plane MBS conversation establishment response aiming at one user plane MBS conversation establishment request in the plurality of user plane MBS conversation establishment requests, and feeding back a refusal message aiming at other user plane MBS conversation establishment requests in the plurality of user plane MBS conversation establishment requests so as to indicate that the user plane node is selected; or alternatively

After feeding back a first user plane MBS session establishment response to the I-SMF, if a user plane MBS session establishment request for selecting the first user plane node as a sub user plane node of other user plane nodes is received again, feeding back a refusal message aiming at the received user plane MBS session establishment request again to indicate that the user plane node is selected.

According to an aspect of an embodiment of the present application, there is provided a communication apparatus for multicast broadcast service, including: a third receiving unit, configured to receive a second user plane MBS session establishment request sent by the I-SMF, where the second user plane MBS session establishment request includes a second MBS IP multicast transmission address and a second C-TEID allocated by the first user plane node selected by the I-SMF; a second sending unit, configured to feed back a second user plane MBS session establishment response to the I-SMF, where the second user plane MBS session establishment response includes a third MBS IP multicast transport address and a third C-TEID allocated by a second user plane node selected by the I-SMF, and the third MBS IP multicast transport address is used for a sub-user plane node of the second user plane node to join a multicast transport group corresponding to the third MBS IP multicast transport address to receive MBS service data transmitted by the second user plane node in a multicast manner; and the second processing unit is configured to join the multicast transmission group corresponding to the second MBS IP multicast transmission address to receive the MBS service data sent by the first user plane node in a multicast manner if the second user plane node supports receiving the MBS service data sent by the first user plane node in a multicast manner.

In some embodiments of the present application, based on the foregoing solution, the second processing unit is further configured to: and if the second user plane node does not support receiving the MBS service data sent by the first user plane node in a multicast mode but in a point-to-point mode, distributing the F-TEID for receiving the MBS service data sent by the first user plane node in the point-to-point mode.

In some embodiments of the present application, based on the foregoing scheme, the third receiving unit is further configured to: after the second sending unit feeds back a second user plane MBS session establishment response to the I-SMF, receiving a second user plane MBS session modification request sent by the I-SMF, wherein the second user plane MBS session modification request comprises first F-TEID list information, and the first F-TEID list information comprises F-TEID of a sub user plane node which does not support receiving MBS service data sent by the second user plane node in a multicast mode but in a point-to-point mode;

the second processing unit is further configured to: and respectively transmitting MBS service data to the sub-user plane nodes corresponding to each F-TEID contained in the first F-TEID list information in a point-to-point mode based on the first F-TEID list information, and determining whether to simultaneously use a multicast transmission mode to transmit the MBS service data to the sub-user plane nodes of the second user plane node according to the second user plane MBS session modification request.

In some embodiments of the present application, based on the foregoing scheme, the second sending unit is further configured to: if receiving a user plane MBS session deletion request sent by the I-SMF, sending a user plane MBS session deletion response to the I-SMF; and if the user terminal is added into the multicast transmission group corresponding to the second MBS IP multicast transmission address, the user terminal exits from the multicast transmission group corresponding to the second MBS IP multicast transmission address after receiving the user terminal MBS session deleting request.

In some embodiments of the present application, based on the foregoing scheme, the second sending unit is configured to: if receiving a plurality of user plane MBS conversation establishment requests, feeding back a user plane MBS conversation establishment request feedback user plane MBS conversation establishment response aiming at one user plane MBS conversation establishment request in the plurality of user plane MBS conversation establishment requests, and feeding back a refusal message aiming at other user plane MBS conversation establishment requests in the plurality of user plane MBS conversation establishment requests so as to indicate that the user plane node is selected; or

After feeding back a second user plane MBS session establishment response to the I-SMF, if a user plane MBS session establishment request for selecting the second user plane node as a sub user plane node of other user plane nodes is received again, feeding back a refusal message aiming at the received user plane MBS session establishment request again to indicate that the user plane node is selected.

According to an aspect of embodiments of the present application, there is provided a computer-readable medium on which a computer program is stored, the computer program, when executed by a processor, implementing a communication method of a multicast broadcast service as described in the above embodiments.

According to an aspect of an embodiment of the present application, there is provided an electronic device including: one or more processors; a storage device for storing one or more programs which, when executed by the one or more processors, cause the one or more processors to implement the communication method of the multicast broadcast service as described in the above embodiments.

According to an aspect of embodiments herein, there is provided a computer program product or computer program comprising computer instructions stored in a computer readable storage medium. The processor of the computer device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions to cause the computer device to perform the communication method of the multicast broadcast service provided in the various optional embodiments described above.

In the technical solutions provided in some embodiments of the present application, an I-level control plane node selects an I-SMF, and then sends a first MBS session start request to the I-SMF, the I-SMF selects, according to the first MBS session start request, a first user plane node capable of establishing a connection with the I-level user plane node, and a second user plane node capable of establishing a connection with both user plane functional entities managed by the first user plane node and a sub-control plane node provided by the I-level control plane node, and at the same time, the I-SMF may send a second MBS session start request to the sub-control plane node provided by the I-level control plane node to instruct the sub-control plane node to assign the sub-user plane node to the second user plane node. The first user plane node can join a multicast transmission group corresponding to a first MBS IP multicast transmission address distributed by the ith user plane node to receive MBS service data sent by the ith user plane node in a multicast mode, the second user plane node can join a multicast transmission group corresponding to a second MBS IP multicast transmission address distributed by the first user plane node to receive MBS service data sent by the first user plane node in a multicast mode, and the sub-user plane node distributed for the second user plane node can join a multicast transmission group corresponding to a third MBS IP multicast transmission address distributed by the second user plane node to receive MBS service data sent by the second user plane node. Therefore, the technical scheme of the embodiment of the application can realize the establishment of the user plane MBS session transmission tree under the communication system architecture with the separation of the control plane and the user plane, and can improve the transmission efficiency of the MBS service data.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and, together with the description, serve to explain the principles of the application. It is obvious that the drawings in the following description are only some embodiments of the application, and that for a person skilled in the art, other drawings can be derived from them without inventive effort. In the drawings:

fig. 1 shows a data transmission flow diagram of a unicast communication system and a multicast communication system;

fig. 2 shows a multicast context activation procedure diagram for MBMS;

FIG. 3 illustrates a classification diagram of IPv4 network addresses;

fig. 4 shows a schematic structural diagram of a multicast address of IPv 4;

fig. 5 shows a structural diagram of a multicast address of IPv 6;

FIG. 6 is a diagram showing the structure of an IPv4 header;

fig. 7 shows a schematic diagram of the protocol header format of IGMPv1, the protocol header format of IGMPv2 and the format of the member report message in IGMPv 3;

fig. 8 shows a schematic diagram of an MBMS registration procedure for an MBMS multicast service;

Fig. 9 shows a schematic diagram of an MBMS session start procedure;

FIG. 10 shows a MBS system architecture diagram;

FIG. 11 is a diagram illustrating an MBS system structure;

fig. 12 shows a flow chart of a communication method of a multicast broadcast service according to an embodiment of the present application;

fig. 13 shows a flow chart of a communication method of a multicast broadcast service according to an embodiment of the present application;

fig. 14A shows a flow chart of a communication method of a multicast broadcast service according to an embodiment of the present application;

fig. 14B shows a flow chart of a communication method of a multicast broadcast service according to an embodiment of the present application;

fig. 15 illustrates a flowchart of an MBS communication method in which a control plane is separated from a user plane according to an embodiment of the present application;

fig. 16 is a flowchart illustrating an MBS communication method in which a control plane is separated from a user plane according to an embodiment of the present application;

fig. 17 is a diagram illustrating a connection relationship between a gNB and a 5GC in an NG-RAN;

fig. 18 illustrates a flowchart of an MBS communication method in which a control plane is separated from a user plane according to an embodiment of the present application;

fig. 19 is a schematic diagram showing a cascade mode of the technical solution of the embodiment of the present application;

fig. 20 is a flowchart illustrating an MBS communication method in which a control plane is separated from a user plane according to an embodiment of the present application;

Fig. 21 illustrates a flowchart of an MBS communication method in which a control plane is separated from a user plane according to an embodiment of the present application;

fig. 22 illustrates a flowchart of an MBS communication method in which a control plane is separated from a user plane according to an embodiment of the present application;

fig. 23 illustrates a flowchart of an MBS communication method in which a control plane is separated from a user plane according to an embodiment of the present application;

fig. 24 shows a block diagram of a communication device for multicast broadcast services according to an embodiment of the present application;

fig. 25 shows a block diagram of a communication device for multicast broadcast services according to an embodiment of the present application;

fig. 26 shows a block diagram of a communication device for multicast broadcast services according to an embodiment of the present application;

fig. 27 shows a block diagram of a communication device for multicast broadcast services according to an embodiment of the present application;

FIG. 28 illustrates a schematic structural diagram of a computer system suitable for use in implementing the electronic device of an embodiment of the present application.

Detailed Description

Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art.

Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments of the application. One skilled in the relevant art will recognize, however, that the subject matter of the present application can be practiced without one or more of the specific details, or with other methods, components, devices, steps, and so forth. In other instances, well-known methods, devices, implementations, or operations have not been shown or described in detail to avoid obscuring aspects of the application.

The block diagrams shown in the figures are functional entities only and do not necessarily correspond to physically separate entities. I.e. these functional entities may be implemented in the form of software, or in one or more hardware modules or integrated circuits, or in different networks and/or processor means and/or microcontroller means.

The flow charts shown in the drawings are merely illustrative and do not necessarily include all of the contents and operations/steps, nor do they necessarily have to be performed in the order described. For example, some operations/steps may be decomposed, and some operations/steps may be combined or partially combined, so that the actual execution sequence may be changed according to the actual situation.

It should be noted that: reference herein to "a plurality" means two or more. "and/or" describe the association relationship of the associated objects, meaning that there may be three relationships, e.g., A and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship.

The wireless communication systems of 2G (second generation mobile communication technology), 3G (third generation mobile communication technology) and 4G (fourth generation mobile communication technology) support MBMS (Multimedia Broadcast and Multicast Service), which is divided into Broadcast and Multicast services. However, only 2G and 3G systems support multicast services, 4G systems are not supported by the standard, and 2G, 3G and 4G systems all support broadcast services.

In addition to broadcast and multicast traffic, the means of communication between network nodes also includes unicast. "unicast" is the most common one-to-one communication, and has the advantage that a sender can transmit different contents to different receivers, but if the sender needs to transmit the same contents to multiple receivers, multiple copies of the same data need to be transmitted respectively end to end, which is inefficient. Specifically, as shown in fig. 1, when a unicast source sends data to multiple receivers in a unicast manner, multiple copies of the same data need to be transmitted in an end-to-end manner (different lines in fig. 1 indicate different data streams).

"multicast," which may also be referred to as "multicast," is where a sender transmits the same content to multiple recipients. The network video conference and the network video on demand are particularly suitable for adopting a multicast mode, because if the unicast mode is adopted, the transmission process is obviously extremely low in efficiency for how many receivers are provided; however, if a broadcasting method of not distinguishing the target and transmitting all data is adopted, the data can be transmitted at one time, but the purpose of distinguishing a specific data receiver cannot be achieved. Therefore, the multicast mode can be adopted, the same data can be sent to a plurality of receivers at one time, and the purpose of only transmitting the data to a specific object can be achieved. As shown in particular in fig. 1, a multicast source may send data identical to data to multiple recipients at one time.

"broadcasting" is also to transmit the same content to a plurality of receivers, but the receivers are not selected at the time of transmission, so that there may be a waste of network resources due to data transmission to unnecessary devices. In addition, some receivers may not have "interest" in the broadcasted content, and then have to discard the received data packets after receiving the broadcasted content, thereby also causing waste of terminal resources.

The fundamental difference between the broadcast service and the multicast service is that UEs (User equipments) in the system can participate in the broadcast service without subscription, while the UEs in the multicast service must subscribe and authenticate before participating. It should be noted that: there are many kinds of multicast services and broadcast services, and for the multicast services, the UE joins a multicast group of the corresponding service through an IP multicast address. A broadcast service corresponding to a broadcast group has its specific service area.

The multicast context activation procedure for MBMS is defined in TS23.246 section 8.2 of the 3GPP (3 rd Generation Partnership Project) protocol, and as shown in fig. 2 in particular, includes the following steps:

step S201, the UE selects an APN (Access Point Name) to establish a PDP (Packet Data Protocol) Context, and then allocates an IP address to the UE, where the APN selected by the UE in this step is identified by APN0 for convenience of subsequent description.

Step S202, the UE selects an IP Multicast Address (the IP Multicast Address is used to identify a Multicast service), and then sends an IGMP Join packet to a GGSN (Gateway GPRS Support Node) to indicate that the UE should Join the Multicast group.

Step S203, GGSN sends MBMS authorization request to BM-SC (Broadcast Multicast Service Center), and receives MBMS authorization response fed back by BM-SC. The BM-SC authenticates whether the UE can join the multicast group according to the subscription data of the UE, and if it is determined that the UE can join the multicast group, gives the APN (which is identified by APN 1) to be used by the UE to join the multicast group in the MBMS authorization response, and then transfers APN1 to be used by the UE to the UE through steps S204a, S204b, and S205.

Step S206, UE initiates a new MBMS Session according to APN1 provided by BM-SC, namely sends a request for activating MBMS context, the request for activating MBMS context includes IP Multicast Address, APN1 and MBMS capability of UE. The MBMS capability may be, for example, a Quality of Service (QoS) capability.

Step S207, the SGSN (Serving GPRS Support Node) checks whether the UE has the subscription APN1, if the check fails, the SGSN sends an MBMS notification rejection request to the GGSN, and the GGSN sends a notification rejection response to the MBMS. It should be noted that the subscription data of the UE is stored in an HSS (Home Subscriber Server), and an interaction procedure between the SGSN and the HSS is not shown in fig. 2. In addition, please refer to the MBMS context activation procedure defined in TS23.246 section 8.2 for the specific procedures of step S208 and step S209 in fig. 2.

Step S210, if the SGSN verifies that the UE passes, the SGSN selects another GGSN (i.e., GGSN supporting Multicast service) according to APN1, and sends a request message for creating an MBMS context to the GGSN, where the message includes an ID of the UE, a Location ID of the UE, an IP Multicast Address, APN1, and access information (e.g., 2G or 3G) of the UE.

The ID of the UE may be an IMSI (International Mobile Subscriber Identity) or an MSISDN (Mobile Station International Integrated Service Digital Network Number). The UE Location ID may be a RAT (Radio Access Technology) ID, a CGI (Common Gateway Interface), an SAI (Service Area Identity), or the like.

Step S211, GGSN sends MBMS authorization request to BM-SC, BM-SC authorizes UE according to UE subscription information, and feeds back MBMS authorization response to GGSN.

Step S212, if the access is authorized and there is no UE context indicated by the IP Multicast Address on the GGSN, that is, the UE is the Multicast service identified by the first access IP Multicast Address on the GGSN, registers with the upper node BM-SC to indicate that the Multicast service data to be sent to the IP Multicast Address needs to be sent to the GGSN when the Multicast service data is sent to the IP Multicast Address later. (note that different UEs may choose to different GGSNs, so when the BM-SC sends multicast data down, it needs to send the same multicast data to these GGSNs at the same time).

In step S213, the GGSN creates an MBMS UE context corresponding to the IP Multicast Address for the UE, and then sends a create MBMS context response to the SGSN to indicate that the MBMS context creation is successful.

Step S214 is similar to step S212, if there is no UE context indicated by the IP Multicast Address on the SGSN, that is, the UE is the Multicast service identified by the first access IP Multicast Address on the SGSN, then the UE registers with the upper node GGSN to indicate that the Multicast service data to be sent to the IP Multicast Address later needs to be sent to the SGSN. (note that different UEs may choose to different SGSNs, so the GGSN needs to send the same multicast data to these SGSNs simultaneously when sending the multicast data down).

The specific process from step S215 to step S217 in fig. 2 please refer to the MBMS context activation process defined in TS23.246, section 8.2.

As can be seen from the flow shown in fig. 2: the method comprises the steps that a PDP Context is established by UE of 2G or 3G through APN0, an IP address is obtained through distribution, then an IGMP Join data packet added with multicast is sent to a network through the IP address, GGSN intercepts the IGMP data packet, then a signaling (namely an MBMS authorization request) is sent to MB-SC, further the BM-SC distributes APN1 to the UE, and then the UE sends a message for requesting MBMS Context activation through the APN1, so that an MBMS Context can be activated.

The aforementioned IP multicast address may be an IPv4 multicast address or an IPv6 multicast address. As shown in fig. 3, the network address of IPv4 is classified into a type a address, a type B address, a type C address, a type D address, and a type E address. Wherein, the 1 st byte (8 bits) in the A-type address is the network number, the other 3 bytes (24 bits) are the host number, and the range of the A-type address is: 0.0.0.0 to 127.255.255.255. The 1 st byte and the 2 nd byte in the B-type address are network numbers, the other 2 bytes are host numbers, and the range of the B-type address is as follows: 128.0.0.0 to 191.255.255.255. The first 3 bytes in the class C address are network numbers, the 4 th byte is a host number, and the range of the class C address is: 192.0.0.0 to 223.255.255.255. The class D address is a multicast address, the first 4 bits of the class address are "1110", the range of the class D address is: 224.0.0.0 to 239.255.255.255. The class E address is a reserved address, the first 5 bits of the class address are "11110", and the range of the class E address is: 240.0.0 to 247.255.255.255.

As shown in fig. 4, the multicast address of IPv4 may have three structures, which are respectively applicable to the Well-Known (Well-Known) multicast address, the global-Scoped multicast address, and the local-Scoped multicast address.

The structure of the IPv6 multicast address is shown in fig. 5, where the first byte (8 bits) indicates that the address is a multicast address, the next 4 bits are a Flag (Flag) field, the next 4 bits are a Scope (Scope) field, and the last 112-bit Group identifier (Group ID).

Wherein, the first bit of the flag bit field is 0 and is reserved for future use; the second bit indicates whether the multicast address is embedded with an RP (Rendezvous Point), where the RP is a distribution Point of a designated multicast stream in the multicast network, for example, when the second bit value is 0, it indicates that an aggregation Point is not embedded, and when the second bit value is 1, it indicates that an aggregation Point is embedded. The third bit of the flag bit field indicates whether prefix information is embedded in the multicast address, for example, when the third bit value is 0, it indicates that no prefix information is embedded, and when the third bit value is 1, it indicates that prefix information is embedded. The last bit of the flag bit field indicates whether the multicast address is a permanently assigned multicast address or a temporary multicast address, for example, if the last bit value is 0, it indicates a permanently assigned multicast address, and if the last bit value is 1, it indicates a temporary multicast address.

The Scope field is used to define the Scope of the multicast address, and the values and descriptions are shown in table 1:

TABLE 1

In multicast communication, a multicast address can only be a destination IP address (i.e., a destination IP address in an IP header), and a multicast address cannot be a source IP address. In the multicast services of MBMS (2G, 3G) and MBS (5G), the multicast packets are all sent to the UE from the network side, i.e. the multicast packets are all DL (Downlink) packets, and the UE cannot send data to the network side through the corresponding multicast address. That is, the UE cannot transmit an Uplink IP packet, i.e., multicast data without UL (Uplink), using the multicast address as a destination IP address.

The IP packet transmitted in the network is composed of an IP header and data, and the structure of the IPv4 header is shown in fig. 6 and mainly includes: a "version" field, a "header length" field, a "service type" field, a "total length" field, an "identification" field, a "flag" field, a "chip offset" field, a "time-to-live" field, a "protocol" field, a "header checksum" field, a "source address" field, a "destination address" field, an "optional field.

The "version" field takes 4 bits and refers to the version of the IP protocol, for example, the version number is 4 (i.e., IPv 4). The "header length" field takes 4 bits. The "service type" field takes 8 bits to get better service. The "total length" field takes 16 bits and refers to the length of the sum of the header and data. The "identification" field takes 16 bits and is a counter that is used to generate the identification of the datagram. The 'flag' field takes 3 bits, the lowest bit of the 'flag' field is MF (More Fragment), if MF =1, it indicates "there is still Fragment" later, and if MF =0, it indicates the last Fragment; one bit in the middle of the "flags" field is DF (Don't Fragment), and fragmentation is allowed only when DF = 0. The "slice offset" field takes 12 bits and refers to the relative position of a slice in the original packet after fragmentation of the longer packet. The "Time To Live" field is TTL (Time To Live), which occupies 8 bits, and the TTL field is a field initially set by the sender. The "Protocol" field occupies 8 bits and is used for indicating which Protocol is used by data carried by the data Message, wherein a value of "1" indicates that the Protocol is an ICMP (Internet Control Message Protocol); a value of "2" indicates IGMP protocol; a value of "6" indicates that it is a TCP (Transmission Control Protocol) Protocol; a value of "17" indicates UDP (User Datagram Protocol) Protocol; a value of "50" indicates that it is the ESP (Encapsulating Security Payload) protocol; a value of "51" indicates an AH (Authentication header) protocol. The "header checksum" field is 16 bits and only the header of the datagram is checked and the data portion is not checked. The "source address" field and the "destination address" field occupy 4 bytes, respectively, for recording the source address and the destination address, respectively.

For the IGMP protocol mentioned above, there are three protocol versions, IGMPv1, IGMPv2 and IGMPv3 respectively, and the corresponding standards are RFC1054, RFC2236 and RFC3376 respectively. The protocol header format of IGMPv1 and the protocol header format of IGMPv2 are shown in fig. 7, wherein the protocol header of IGMPv1 includes a 4-bit IGMP version field, a 4-bit IGMP packet type field (the field value is 1 indicating Host Membership Query, i.e., a Host Membership Query type; the value is 2 indicating Host Membership Report, i.e., a Host Membership Report type), an 8-bit unused field (the field is filled with 0 at the time of transmission and ignored at the time of reception), a 16-bit IGMP checksum field (the checksum must be calculated and inserted into the field when transmitting a packet; the field must be checked before processing a packet when receiving a packet), and a 32-bit multicast address field.

The protocol header of IGMPv2 includes an 8-bit message type field, an 8-bit maximum response time field, a 16-bit IGMP checksum field, and a 32-bit multicast address field.

The types indicated by the message type field in the protocol header of IGMPv2 include the following: 0x11= membership Query, which indicates an IGMP membership Query message; 0x12= version 1membership Report, which represents a member Report message of IGMPv 1; 0x16= version 2Membership Report, which represents a member Report message of IGMPv 2; 0x17= leave Group indicates a leave message. In IGMPv2, the old 4-bit version field and the old 4-bit type field are spliced into a new 8-bit type field, and backward compatibility of IGMP version 1 and version 2 packet formats is maintained by setting the type codes of the membership query message (version 1 and version 2) and the membership report message of version 1 to 0x11 and 0x12, respectively.

The maximum response time field in the protocol header of IGMPv2 is used to indicate the maximum time (in units of 1/10 second) before sending out a response report, with a default value of 10 seconds. Similar to IGMPv1, when transmitting a message, a checksum must be calculated and filled in a checksum field in a protocol header of IGMPv2, and when receiving a message, the checksum must be checked before processing the message to determine whether an error occurs in the IGMP message during transmission.

As shown with continued reference to fig. 7, the format of the Membership Report message (Membership Report) in IGMPv3 includes a type field (type =0x22 because it is a Membership Report message), a reserved field, a checksum field, a number of group records field, and a group records field. The IGMP Join packet shown in fig. 2 is implemented by the Membership Report message of IGMP. For IGMPv3, the destination IP address in the IP packet of the IGMP join message is not the IP multicast address to join, but the IP multicast address to join is included in the parameters of the message.

Section 8.4 of the standard TS23.246 defines an MBMS registration procedure applicable to MBMS multicast services, and as shown in fig. 8 in particular, includes the following steps: step S801, an RNC (Radio Network Controller) sends an MBMS registration request to an SGSN; step S802, SGSN sends MBMS register request to GGSN; step S803, GGSN sends MBMS registration request to BM-SC; step S804, BM-SC feeds back MBMS register response to GGSN, and can execute MBMS conversation starting course; step S805, GGSN feeds back MBMS registration response to SGSN, and can execute MBMS conversation starting process; in step S806, the SGSN feeds back the MBMS registration response to the RNC, and may perform the MBMS session start procedure. It can be seen that the main function of the MBMS registration procedure is to form a signaling tree from top to bottom that controls the Bearer establishment (MBMS Bearer Context). Since the control plane and the user plane are not separated in the 2g,3g standard, forming the transmission tree of the MBMS bearer control plane on the control plane is equivalent to subsequently establishing a transmission tree of the MBMS bearer from top to bottom (note that the transmission tree of the MBMS bearer is established by the MBMS Session Start procedure). In addition, since 4G does not support multicast services, there is no MBMS registration procedure in the 4G standard.

Section 8.3 of the standard TS23.246 defines the MBMS session start procedure, which, as shown in fig. 9 in particular, comprises the following steps: step S901, BM-SC sends MBMS conversation start request to GGSN, GGSN feeds back MBMS conversation start response to BM-SC; step S902, GGSN sends MBMS conversation start request to SGSN, then SGSN feeds back MBMS conversation start response to GGSN; step S903, SGSN sends MBMS conversation start request to BSC (Base Station Controller)/RNC, then BSC/RNC feeds back MBMS conversation start response to SGSN; step S904, MBMS conversation starting process is carried out between UE and RSC/RNC; in step S903a, the BSC/RNC sends an IGMPv3 membership report message.

For the Multicast service of MBMS, the MBMS registration procedure and the MBS session start procedure are both Per IP Multicast procedures, which are to establish a signaling tree of MBMS bearer context of control plane from top to bottom and a transmission tree of MBMS bearer from top to bottom for the IP Multicast, instead of Per UE Per IP Multicast. For the Broadcast service of MBMS, there is no MBMS registration procedure, and the MBS session start procedure is a Per IP Broadcast procedure, which is to establish a signaling tree of MBMS bearer context of the control plane from top to bottom and a transmission tree of MBMS bearer from top to bottom for this IP Broadcast, instead of Per UE Per IP Broadcast.

However, for the Multicast service of MBMS, in order to optimize the registration process, during the MBMS UE Context activation process performed by the UE, a part of the MBMS registration process, such as step S212 and step S214 shown in fig. 2, may be performed by the way, but this is only performed when the first UE of the SGSN and the GGSN activates the IP Multicast service, and when there is a second UE activating the IP Multicast service on the same SGSN and GGSN, step S212 and step S214 shown in fig. 2 are not performed any more.

For the multicast service and the broadcast service of the MBMS, an important function is to form a transmission tree of the user plane of the multicast service and the broadcast service, to prevent the formation of a transmission ring of the user plane (i.e. there are a plurality of different transmission paths to reach a certain node), and to prevent the occurrence of MBMS branches (i.e. there is no downstream node in a certain node).

In 2G to 3G systems, multiple SGSNs may constitute a Pool. Although the GGSN does not define Pool in the standard, in actual deployment, there exists a GGSN Pool to provide high reliability of the system. Thus, when different UEs access to the same BSC/RNC and activate the same MBMS IP Multicast, it is possible for the BSC/RNC to select different SGSNs in the same SGSN Pool. But since the APNs used by these UEs are the same, different SGSNs in these same SGSN Pool will select to different GGSNs, but possibly the SGSNs are connected to the same GGSN. The 3GPP standard specifies that when the RNC uses the Iu interface, the SGSN Pool is allowed to be selected, and for MBMS, the GGSN is required to connect directly to the RNC using the GTP-U (GPRS Tunneling Protocol-User plane) and the User plane is not allowed to pass through the SGSN. Thus, even if different users on the same RNC select different SGSNs using the same APN and IP Multicast, their user planes are eventually the same and there are no multiple different user planes.

However, for the BSC there may be multiple SGSNs to which to send MBMS session start request messages, for which case only one user plane is implemented by the BSC/RNC rejecting MBMS session start request messages of other SGSNs as defined in standard TS 23.236. Similarly, when multiple GGSNs send an MBMS session start request message to an SGSN, the SGSN can also select only one GGSN to establish a bearer plane, thereby preventing the occurrence of an MBMS transmission ring.

When the BSC/RNC rejects the bearer establishment of an SGSN, it may cause the SGSN to have no downstream node, and in this case, the SGSN only needs to delete itself from the downstream node of the GGSN by a DeRegistration (DeRegistration) technique (refer to section 8.6.0 of standard TS23.236, specifically), so as to prevent the GGSN from sending the multicast data of the MBMS to the SGSN, but the SGSN cannot transmit the MBMS data downward, thereby avoiding the occurrence of MBMS transmission disconnection. Similarly, when the SGSN rejects the bearer establishment of the GGSN, it may cause the GGSN to have no downstream node, and in this case, the GGSN only needs to delete itself from the downstream node of the BM-SC by the DeRegistration technology, so as to prevent the BM-SC from sending the multicast data of the MBMS to the GGSN, and avoid the occurrence of MBMS transmission branch interruption.

I.e. for MBMS multicast services, any node must have a downstream node except the final transmission point UE. If a node has no downstream nodes, this node should leave the transmission tree (corresponding to the Deregistration process). For example, when all MBMS UEs under one base station move to other base stations, the base station needs to perform de-registration operation to the SGSN; when all MBMS connection base stations under one SGSN carry out Deregistration operation, the SGSN needs to carry out Deregistration operation to GGSN; when all MBMS connection SGSNs under a GGSN perform Deregistration operation, the GGSN needs to perform the Deregistration operation to the BM-SC.

In addition, since the transmission path of the MBMS service (including the broadcast service and the multicast service) is a tree structure, one or more child nodes are located below each parent node, and the bearers between the parent node and the child nodes can be based on GTP tunnels between the parent node and the child node. However, when the number of the child nodes is extremely large, the parent node needs to send the same IP Multicast data to many child nodes at the same time, and obviously, the transmission mode through the GTP tunnel is very inefficient. In order to improve the transmission efficiency between the parent node and the child node on the network side, the parent node may allocate a local IP Multicast address (this address is not a Multicast address in the MBMS Multicast service), and the IP Multicast address of this transmission layer is used for efficiently transmitting MBMS service data between the child node (e.g., a base station) and the parent node (e.g., an MBMS GW or a GGSN). In this case, the parent node only needs to send the MBMS service data through the multicast address of the transport layer, and all the child nodes can receive the MBMS service data, thereby greatly reducing the data processing amount of the parent node.

To use the Multicast-based bearer transport optimization technique, a parent node needs to allocate a local IP Multicast transport layer address, and after receiving the IP Multicast transport layer address allocated by the parent node, a child node needs to Join a Multicast group of the transport layer through an IGMP Join process. Because some sub-nodes do not support multicast, there may exist a part of sub-nodes receiving MBMS service data in a transport layer multicast manner, and another part of sub-nodes respectively using a point-to-point GTP Tunnel manner, in which case, the sub-nodes allocate an IP address and a TEID of a downlink GTP-U. Of course, if the parent node finds a small number of child nodes, it may decide not to use the multicast transmission scheme.

Because the control plane and the user plane in the MBMS system are not separated, namely, the network nodes both comprise the functions of the user plane and the control plane, when a certain network node does not support the multicast transmission technology, the father node can know that the node does not support the multicast transmission after directly replying an IP address and a TEID of a GTP-U. However, in the 5G MBS system, the control plane and the user plane are separated, and the control plane and the user plane are no longer the same network node, in which case, establishing the MBS session transmission tree will face various problems.

And two system architectures as shown in fig. 10 and fig. 11 are defined in the latest research report of 5G MBS, where the system architecture shown in fig. 10 is a system architecture that overlaps functions on the current 5G architecture, that is, the 5G MBS service is supported by enhancing the functions and interfaces of the 5G architecture without modifying the current 5G architecture, and this architecture has the advantage of supporting 5G MBS through software upgrade. The system architecture shown in fig. 11 is a completely new architecture, i.e. new network function nodes are added under the situation that the current 5G architecture is not changed. The advantage of this architecture is that the impact on the current 5G architecture is minimized, but some Network Function nodes may still need to be enhanced, such as NG-RAN (Next Generation Radio Access Network), AMF, UDM (Unified Data Management), UDR (User Data Repository), NEF (Network Exposure Function), PCF, etc.

The SMF in fig. 10 is a Session Management Function; UPF is User Plane Function, i.e., user Plane Function; AF is an Application Function, i.e., an Application Function. MB-UPF in FIG. 11 is Multicast/Broadcast-UPF; MB-SMF is Multicast/Broadcast-SMF; the MBSU is a Multicast/Broadcast Service User Plane (Multicast/Broadcast Service User Plane); the MBSF is a Multicast/Broadcast Service Function (MBMS entity).

The following embodiments will introduce the related technical contents of the user plane MBS session transmission tree for the 5G MBS system, and are described in detail as follows:

fig. 12 shows a flowchart of a communication method of a multicast broadcast service according to an embodiment of the present application, where the communication method of the multicast broadcast service may be performed by an I-SMF, and the communication method of the multicast broadcast service at least includes steps S1210 to S1230, which are described in detail as follows:

in step S1210, a first MBS session start request sent by an i-th level control plane node in an MBS session transmission tree is received, where the first MBS session start request includes information of sub-control plane nodes provided by the i-th level control plane node, identification information of an i-th level user plane node selected by the i-th level control plane node, a first MBS IP multicast transmission address allocated by the i-th level user plane node, and a first C-TEID for transmitting MBS service data in a multicast manner.

In an embodiment of the present application, the ith level control plane node may select one or more user plane functional entities from the managed user plane functional entities as the ith level user plane node according to information of the child control plane nodes of the ith level control plane node. Meanwhile, if the I-th level control plane node determines that the user plane functional entity managed by the I-th level control plane node cannot establish a transmission path with the user plane functional entity managed by the sub-control plane node of the I-th level control plane node according to the information of the sub-control plane node of the I-th level control plane node, the SMF capable of communicating with the I-th level control plane node and the sub-control plane node of the I-th level control plane node may be selected as the I-SMF.

For example, if the service area of the I-th level control plane node is a and the service area of the sub-control plane node of the I-th level control plane node is C, that is, the user plane functional entity managed by the I-th level control plane node cannot directly communicate with the user plane functional entity managed by the sub-control plane node of the I-th level control plane node, the I-th level control plane node may select an I-SMF, and the I-SMF needs to be able to communicate with the I-th level control plane node and the sub-control plane node of the I-th level control plane node.

In an embodiment of the application, after the ith level control plane node selects the ith level user plane node, the ith level control plane node may perform a user plane MBS session establishment process with the ith level user plane node, that is, send a user plane MBS session establishment request to the ith level user plane node, receive a user plane MBS session establishment response fed back by the ith level user plane node, and then obtain a first MBS IP multicast transmission address and a first C-TEID allocated to the ith level user plane node from the user plane MBS session establishment response fed back by the ith level user plane node. After the I-th level control plane node determines the information, the first MBS conversation starting request is sent to the selected I-SMF, and the information is added in the first MBS conversation starting request, namely the information of the sub control plane node provided by the I-th level control plane node, the identification information of the I-th level user plane node, the first MBS IP multicast transmission address distributed by the I-th level user plane node and the first C-TEID are added.

In step S1220, a first user plane node capable of establishing a connection with the i-th level user plane node and a second user plane node capable of establishing a connection with both the first user plane node and a user plane functional entity managed by the sub control plane node provided by the i-th level control plane node are selected according to the information of the i-th level control plane node and the information of the sub control plane node provided by the i-th level control plane node.

In an embodiment of the present application, the information of the ith level control plane node may include a service area of the ith level control plane node, the information of the sub control plane node provided by the ith level control plane node may include a service area of the sub control plane node provided by the ith level control plane node, and the I-SMF needs to select, according to the information, a first user plane node capable of establishing a connection with the ith level user plane node and a second user plane node capable of establishing a connection with both the first user plane node and a user plane functional entity managed by the sub control plane node provided by the ith level control plane node.

In step S1230, a first user plane MBS session establishment request is sent to the first user plane node, and a first user plane MBS session establishment response fed back by the first user plane node is received, where the first user plane MBS session establishment request includes a first MBS IP multicast transmission address and a first C-TEID, and the first MBS IP multicast transmission address is used to enable the first user plane node to join a multicast transmission group corresponding to the first MBS IP multicast transmission address to receive MBS service data sent by the i-th level user plane node in a multicast manner.

In an embodiment of the present application, if the first user plane node does not support receiving MBS service data sent by an I-level user plane node in a multicast manner but supports receiving MBS service data sent by an I-level user plane node in a point-to-point manner, a first user plane MBS session establishment request sent by the I-SMF to the first user plane node includes indication information requesting to allocate an F-TEID to the first user plane node, in this case, a first user plane MBS session establishment response fed back by the first user plane node includes the F-TEID allocated by the first user plane node, and the F-TEID is used for enabling the first user plane node to receive MBS service data sent by the I-level user plane node in a point-to-point manner.

In an embodiment of the application, if the I-SMF does not know whether the first user plane node does not support receiving the data transmitted in the multicast mode, or if the I-SMF does not make a decision even if it knows that the first user plane node does not support receiving the data transmitted in the multicast mode, the first user plane node may indicate, through the first user plane MBS session establishment response, that the first user plane node does not support receiving MBS service data transmitted by the I-th user plane node in the multicast mode but in a peer-to-peer mode, and include an F-TEID allocated by the first user plane node.

In an embodiment of the present application, if the ith control plane node selects at least two ith user plane nodes, a first MBS session start request sent by the I-SMF to the first user plane node includes respective identification information of each ith user plane node, a first MBS IP multicast transmission address and a first C-TEID allocated to each ith user plane node. Wherein, the first MBS IP multicast transmission addresses distributed by different i-th level user plane nodes are different.

Continuing to refer to fig. 12, in step S1240, sending a second user plane MBS session establishment request to the second user plane node, and receiving a second user plane MBS session establishment response fed back by the second user plane node, where the second user plane MBS session establishment request includes a second MBS IP multicast transmission address and a second C-TEID allocated by the first user plane node, and the second MBS IP multicast transmission address is used to enable the second user plane node to join a multicast transmission group corresponding to the second MBS IP multicast transmission address to receive MBS service data sent by the first user plane node in a multicast manner.

In an embodiment of the present application, the I-SMF may obtain the second MBS IP multicast transmission address and the second C-TEID allocated by the first user plane node from the first user plane MBS session establishment response fed back by the first user plane node. Specifically, a first user plane MBS session establishment request sent by the I-SMF to the first user plane node contains indication information used for indicating the first user plane node to allocate new MBS IP multicast distribution information, and a first user plane MBS session establishment response fed back by the first user plane node to the I-SMF contains a second MBS IP multicast transmission address and a second C-TEID allocated by the first user plane node.

In an embodiment of the present application, if the second user plane node does not support receiving MBS service data of the first user plane node in a multicast manner but in a point-to-point manner, the second user plane MBS session establishment request sent by the I-SMF to the second user plane node includes indication information requesting to allocate an F-TEID to the second user plane node, in this case, the second user plane MBS session establishment response fed back by the second user plane node includes the F-TEID allocated by the second user plane node, and the F-TEID allocated by the second user plane node is used for enabling the second user plane node to receive the MBS service data sent by the first user plane node in a point-to-point manner.

In an embodiment of the application, if the I-SMF does not know whether the second user plane node does not support receiving the data transmitted in the multicast mode, or if the I-SMF does not make a decision even if it knows that the second user plane node does not support receiving the data transmitted in the multicast mode, the second user plane node may indicate, through the second user plane MBS session establishment response, that the second user plane node does not support receiving the MBS service data transmitted by the first user plane node in the multicast mode but in a point-to-point mode, and include the F-TEID allocated by the second user plane node.

In an embodiment of the present application, after receiving a second user plane MBS session establishment response fed back by a second user plane node, if it is determined that there is a second user plane node that does not support receiving MBS service data sent by a first user plane node in a multicast manner but in a point-to-point manner according to the second user plane MBS session establishment response, the I-SMF sends a first user plane MBS session modification request to the first user plane node, where the first user plane MBS session modification request includes an F-TEID allocated to the second user plane node that does not support receiving MBS service data sent by the first user plane node in a multicast manner, so that the first user plane node transmits the MBS service data to the second user plane node that does not support receiving MBS service data sent by the first user plane node in a point-to-point manner.

It should be noted that: if a second user plane node supporting receiving the MBS service data sent by the first user plane node in a multicast mode exists at the same time, the first user plane MBS conversation modification request also comprises a field starting the multicast mode transmission so as to indicate the first user plane node to send the MBS service data to the second user plane node in the multicast transmission mode at the same time.

In an embodiment of the present application, if all the second user plane nodes selected by the I-SMF cannot establish communication with a certain first user plane node, the first user plane node will have no downstream node, in which case there is a branch break in the user plane MBS session transmission tree, and therefore the I-SMF needs to send a user plane MBS session deletion request to the first user plane node. In addition, if all the ues served by a certain first user plane node move to other areas, i.e. the first user plane node does not need to provide services to the ues any more, the I-SMF may also send a request for deleting the user plane MBS session to the first user plane node.

Continuing to refer to fig. 12, in step S1250, a second MBS session start request is sent to the sub-control plane node provided by the i-th level control plane node to instruct the sub-control plane node provided by the i-th level control plane node to allocate a sub-user plane node to the second user plane node, where the second MBS session start request includes a third MBS IP multicast transmission address and a third C-TEID allocated by the second user plane node, and the third MBS IP multicast transmission address is used to enable the sub-user plane node provided by the i-th level control plane node to join a multicast transmission group corresponding to the third MBS IP multicast transmission address to receive MBS service data sent by the second user plane node in a multicast manner.

In an embodiment of the present application, after sending the second MBS session start request to the sub-control plane node provided by the I-th level control plane node, the I-SMF further needs to receive a second MBS session start response fed back by the sub-control plane node provided by the I-th level control plane node with respect to the second MBS session start request, where the second MBS session start response includes the first indication information. The content contained in the first indication information may be as follows:

case 1: in an embodiment of the application, the first indication information includes identification information of the second user plane node, first F-TEID list information, and first field information used for indicating that multicast mode transmission is started, where the first field information indicates that a sub-user plane node allocated by a sub-control plane node provided by an ith-level control plane node for the second user plane node exists in the sub-user plane nodes, the sub-user plane node supports receiving MBS service data sent by the second user plane node in a multicast mode, the first F-TEID list information includes F-TEIDs of the sub-user plane nodes, which do not support receiving the MBS service data sent by the second user plane node in a multicast mode but support receiving the MBS service data sent by the second user plane node in a peer-to-peer mode, and the F-TEIDs are used for enabling the sub-user plane nodes of the second user plane node to receive the MBS service data sent by the second user plane node in a peer-to-peer mode.

Case 2: in an embodiment of the present application, the first indication information includes identification information of the second user plane node, and does not include the first F-TEID list information and the first field information, and in this case, the first indication information is used to indicate that the sub-user plane nodes provided by the ith-level control plane node support receiving, by multicast, MBS service data sent by the second user plane node for the sub-user plane nodes allocated to the second user plane node.

Case 3: in an embodiment of the present application, the first indication information includes identification information of the second user plane node, the first F-TEID list information, and does not include the first field information, and in this case, the first indication information is used to indicate that none of the sub-user plane nodes provided by the ith level control plane node support receiving, in a multicast manner, MBS service data sent by the second user plane node in a point-to-point manner.

Case 4: in an embodiment of the present application, the first indication information includes identification information of the second user plane node and field information for deactivating multicast transmission, and does not include the first F-TEID list information, in which case the first indication information is used to indicate that the sub-control plane node provided by the ith level control plane node does not allocate the sub-user plane node to the second user plane node. Alternatively, the field information for disabling the Multicast transmission may be to set a value of Multicast Enable to Disable.

In an embodiment of the present application, if the I-SMF selects at least two second user plane nodes, a second MBS session start response fed back to the I-SMF by a child control plane node provided by the I-level control plane node includes a first indication information list, where the first indication information list includes first indication information corresponding to all second user plane nodes.

In an embodiment of the present application, the second MBS session start response fed back to the I-SMF by the sub-control plane node of the ith-level control plane node may further include a failed identification information list, where the failed identification information list is used to indicate a target second user plane node to which the sub-user plane node is not allocated.

In an embodiment of the present application, if the I-SMF determines, according to the second MBS session start response fed back by the child control plane node of the I-th level control plane node, that there is a target second user plane node to which the child user plane node is not allocated, then sends a user plane MBS session deletion request to the target second user plane node. The technical scheme of the embodiment is to delete the broken branches in the user plane MBS session transmission tree.

In an embodiment of the present application, after sending a user plane MBS session deletion request to a target second user plane node to which a sub-user plane node is not allocated, the I-SMF may further receive a user plane MBS session deletion response fed back by the target second user plane node, where the user plane MBS session deletion response is sent by the target second user plane node after receiving the user plane MBS session deletion request, and if the target second user plane node has added to a multicast transmission group corresponding to a second MBS IP multicast transmission address, the I-SMF exits the multicast transmission group corresponding to the second MBS IP multicast transmission address after receiving the user plane MBS session deletion request.

In an embodiment of the present application, if the ith control plane node provides at least two sub-control plane nodes, the I-SMF determines whether there is a target second user plane node to which a sub-user plane node is not allocated after receiving second MBS session start responses fed back respectively by all the sub-control plane nodes provided by the ith control plane node, and avoids a deviation in determining whether there is a target second user plane node to which a sub-user plane node is not allocated according to the second MBS session start responses fed back by receiving part of the sub-control plane nodes.

In an embodiment of the present application, after receiving a second MBS session start response fed back by a sub-control plane node provided by an I-th level control plane node for a second MBS session start request, the I-SMF may determine, according to the second MBS session start response, which manner the second user plane node transmits MBS service data to the sub-user plane node of the second user plane node, respectively.

Specifically, if the first indication information in the second MBS session start response includes the first F-TEID list information, the I-SMF sends a user plane MBS session modification request to the second user plane node according to the identification information of the second user plane node included in the first indication information, so as to instruct the second user plane node to transmit MBS service data to the sub-user plane nodes corresponding to each F-TEID included in the first F-TEID list information in a point-to-point manner, respectively. Wherein, if the first indication information further comprises the first field information, the user plane MBS session modification request is further used to indicate the second user plane node to send MBS service data to the sub-user plane nodes of the second user plane node simultaneously using a multicast transmission mode; if the first indication information does not contain the first field information, the user plane MBS session modification request is further used to indicate that the second user plane node does not need to use a multicast transmission mode to send MBS service data to the child user plane nodes of the second user plane node.

It should be noted that, if the first indication information in the second MBS session start response does not include the first F-TEID list information and the first field information, it indicates that all the sub-user plane nodes of the second user plane node support receiving multicast transmission, and then the second user plane node may transmit MBS service data to all the sub-user plane nodes of the second user plane node in a multicast transmission manner.

In an embodiment of the present application, if the I-SMF selects at least two second user plane nodes, the I-SMF may send a user plane MBS session modification request to a second user plane node that needs to send the user plane MBS session modification request according to first indication information corresponding to each second user plane node included in a second MBS session start response. Specifically, if it is determined that some of the sub-user plane nodes of a certain second user plane node do not support receiving MBS service data sent by the second user plane node in a multicast manner but in a point-to-point manner according to a second MBS session start response fed back by the sub-control plane node provided by the ith-level control plane node, it indicates that the second user plane node is the second user plane node that needs to send a user plane MBS session modification request.

In an embodiment of the present application, after receiving a second MBS session start response fed back by a sub control plane node of an I-th level control plane node for a second MBS session start request, the I-SMF may also feed back a first MBS session start response for a first MBS session start request to the I-th level control plane node according to the second MBS session start response. If the I-level control plane node provides at least two sub control plane nodes, the I-SMF needs to feed back a first MBS session start response to the I-level control plane node after receiving second MBS session start responses respectively fed back by all the sub control plane nodes provided by the I-level control plane node.

Similar to the second MBS session start response fed back by the sub-control plane node provided by the ith-level control plane node, in an embodiment of the present application, the first MBS session start response fed back to the ith-level control plane node by the I-SMF includes the second indication information. The content contained in the second indication information may be as follows:

case 1: in an embodiment of the present application, the second indication information includes identification information of an i-th user plane node, second F-TEID list information, and second field information for indicating that multicast mode transmission is started, where the second field information indicates that there is an intermediate user plane node that supports receiving MBS service data sent by the i-th user plane node in a multicast mode, the second F-TEID list information includes an F-TEID of a first user plane node that does not support receiving MBS service data sent by the i-th user plane node in a multicast mode but supports receiving MBS service data sent by the i-th user plane node in a point-to-point mode, and the F-TEID is used for enabling the first user plane node to receive MBS service data sent by the i-th user plane node in a point-to-point mode.

Case 2: in an embodiment of the present application, the second indication information includes identification information of an i-th level user plane node, and does not include the second F-TEID list information and the second field information, and in this case, the second indication information is used to indicate that the first user plane nodes all support receiving MBS service data sent by the i-th level user plane node in a multicast manner.

Case 3: in an embodiment of the present application, the second indication information includes identification information of an i-th level user plane node, the second F-TEID list information, and does not include the second field information, and in this case, the second indication information is used to indicate that none of the first user plane nodes support receiving MBS service data sent by the i-th level user plane node in a multicast manner but in a peer-to-peer manner.

In an embodiment of the present application, if the ith-level control plane node selects at least two ith-level user plane nodes, the first MBS session start response fed back to the ith-level control plane node by the I-SMF includes a second indication information list, where the second indication information list includes second indication information corresponding to all the ith-level user plane nodes.

In an embodiment of the present application, if the I-SMF selects at least two first user plane nodes and at least two second user plane nodes, the I-SMF needs to send a second user plane MBS session establishment request to each selected second user plane node, where the second user plane MBS session establishment request sent to each second user plane node includes a second MBS IP multicast transmission address and a second C-TEID allocated by the corresponding first user plane node; wherein, the second MBS IP multicast transmission addresses distributed by different first user plane nodes are different.

Fig. 12 is a diagram illustrating a communication method of a multicast broadcast service according to an embodiment of the present application from the perspective of I-SMF, and the communication method of the multicast broadcast service according to the embodiment of the present application is further described below with reference to fig. 13 from the perspective of an I-th level control plane node:

fig. 13 is a flowchart illustrating a communication method of a multicast broadcast service according to an embodiment of the present application, where the communication method of the multicast broadcast service may be performed by an ith-level control plane node, and the communication method of the multicast broadcast service includes at least steps S1310 to S1320, which are described in detail as follows:

in step S1310, a second user plane MBS session establishment request is sent to the i-th user plane node selected by the i-th control plane node, and a second user plane MBS session establishment response fed back by the i-th user plane node is received, where the i-th control plane node is any level of control plane node except for the last level of control plane node in the MBS session transmission tree.

In an embodiment of the present application, the ith level control plane node may select one or more user plane functional entities from the managed user plane functional entities as the ith level user plane node according to information of the child control plane nodes of the ith level control plane node. After the ith level control plane node selects the ith level user plane node, the ith level control plane node can perform a user plane MBS session establishment process with the ith level user plane node, namely, a second user plane MBS session establishment request is sent to the ith level user plane node, a second user plane MBS session establishment response fed back by the ith level user plane node is received, and then a first MBS IP multicast transmission address and a first C-TEID distributed by the ith level user plane node are obtained from the second user plane MBS session establishment response fed back by the ith level user plane node.

In step S1320, select an I-SMF, and send a first MBS session start request to the I-SMF, where the first MBS session start request includes information of the sub-control plane node provided by the ith-level control plane node, identification information of the ith-level user plane node, a first MBS IP multicast transmission address allocated by the ith-level user plane node, and a first C-TEID.

In an embodiment of the present application, the first MBS session start request is used to trigger the I-SMF to select a first user plane node capable of establishing a connection with the I-th level user plane node, and a second user plane node capable of establishing a connection with both a user plane functional entity managed by the first user plane node and a sub-control plane node, and to trigger the I-SMF to send a second MBS session start request to the sub-control plane node provided by the I-th level control plane node. The first user plane node is used for joining a multicast transmission group corresponding to a first MBS IP multicast transmission address to receive MBS service data sent by an i-level user plane node in a multicast mode, the second user plane node is used for joining a multicast transmission group corresponding to a second MBS IP multicast transmission address distributed by the first user plane node to receive MBS service data sent by the first user plane node in the multicast mode, and the second MBS session starting request is used for indicating a sub-control plane node provided by the i-level control plane node to distribute the sub-user plane node for the second user plane node and enabling the distributed sub-user plane node to receive the MBS service data sent by the second user plane node.

In an embodiment of the present application, if the ith level control plane node provides two or more sub-control plane nodes, the first MBS session start request sent by the ith level control plane node to the I-SMF may include a list of sub-control plane nodes, where the list includes information of all sub-control plane nodes provided by the ith level control plane node.

In one embodiment of the present application, the purpose of the level I control plane node to select the intermediate session management function entity I-SMF is: if the I-th level control plane node determines that the user plane functional entity managed by the I-th level control plane node cannot establish a transmission path with the user plane functional entity managed by the sub-control plane node of the I-th level control plane node, an SMF capable of communicating with the I-th level control plane node and with the sub-control plane node of the I-th level control plane node may be selected as the I-SMF. In this way, when the user plane transmission of direct connection cannot be established between the I-level user plane node and the downstream user plane node (usually a base station or a Distribution Unit (DU) of the base station) in the user plane MBS session establishment process, the I-SMF may be inserted, and then the I-SMF may select the first user plane node and the second user plane node to complete the establishment of the user plane MBS session transmission tree, thereby effectively implementing the optimization of the user plane transmission resources.

In an embodiment of the present application, after sending the first MBS session start request to the I-SMF, the ith control plane node may further receive a first MBS session start response fed back by the I-SMF in response to the first MBS session start request, and in this case, the ith control plane node may determine whether to send the user plane MBS session modification request to the ith user plane node according to the content included in the first MBS session start response. Specifically, if it is determined that a certain/some first user plane nodes do not support receiving MBS service data sent by an I-level user plane node in a multicast manner but in a point-to-point manner according to a first MBS session start response fed back by the I-SMF, a user plane MBS session modification request needs to be sent to the I-level user plane node.

Fig. 13 is a diagram illustrating a communication method of a multicast broadcast service according to an embodiment of the present invention from the perspective of an i-th level control plane node, and the following further illustrates the communication method of the multicast broadcast service according to the embodiment of the present invention from the perspective of the first user plane node and the second user plane node, respectively, with reference to fig. 14A and 14B:

fig. 14A shows a flowchart of a communication method of a multicast broadcast service according to an embodiment of the present application, which may be performed by the first user plane node, and includes at least steps S1410 to S1430, which are described in detail as follows:

In step S1410, a first user plane MBS session establishment request sent by the I-SMF is received, where the first user plane MBS session establishment request includes a first MBS IP multicast transmission address and a first C-TEID allocated by the I-level user plane node.

In step S1420, a first user plane MBS session establishment response is fed back to the I-SMF, where the first user plane MBS session establishment response includes a second MBS IP multicast transmission address and a second C-TEID allocated by the first user plane node selected by the I-SMF, and the second MBS IP multicast transmission address is used to enable the second user plane node selected by the I-SMF to join a multicast transmission group corresponding to the second MBS IP multicast transmission address to receive MBS service data transmitted by the first user plane node in a multicast manner.

In step S1430, if the first user plane node supports receiving MBS service data sent by the ith user plane node in a multicast manner, the first user plane node adds a multicast transmission group corresponding to the first MBS IP multicast transmission address to receive MBS service data sent by the ith user plane node in a multicast manner.

In an embodiment of the present application, if the first user plane node does not support receiving MBS service data sent by an i-th user plane node in a multicast manner but in a point-to-point manner, the first user plane node may allocate an F-TEID for receiving the MBS service data sent by the i-th user plane node in a point-to-point manner.

In an embodiment of the application, after feeding back a first user plane MBS session establishment response to the I-SMF, a first user plane node may also receive a first user plane MBS session modification request sent by the I-SMF, where the first user plane MBS session modification request includes an F-TEID allocated to a second user plane node that does not support receiving MBS service data sent by the first user plane node in a multicast manner, and then the first user plane node may transmit, in a point-to-point manner, MBS service data to a second user plane node that does not support receiving MBS service data sent by the first user plane node in a multicast manner but supports receiving MBS service data sent by the first user plane node in a point-to-point manner based on an F-TEID of a second user plane node that does not support receiving MBS service data sent by the first user plane node in a multicast manner but supports receiving MBS service data sent by the point-to-point manner, and determine whether to send service data to other second user plane nodes in a multicast transmission manner at the same time according to the first user plane MBS session modification request. Please refer to the technical solutions of the foregoing embodiments, which are not described in detail.

In an embodiment of the application, if a first user plane node receives a user plane MBS session deletion request sent by an I-SMF, sending a user plane MBS session deletion response to the I-SMF; if the first user plane node has joined in the multicast transmission group corresponding to the first MBS IP multicast transmission address, the multicast transmission group corresponding to the first MBS IP multicast transmission address is exited after the user plane MBS conversation deleting request is received. The technical scheme of the embodiment is to delete the broken branches in the user plane MBS session transmission tree.

In an embodiment of the present application, if a first user plane node receives a plurality of user plane MBS session establishment requests, a user plane MBS session establishment request feedback user plane MBS session establishment response is sent for one of the plurality of user plane MBS session establishment requests, and a feedback reject message is sent for other user plane MBS session establishment requests in the plurality of user plane MBS session establishment requests to indicate that the user plane node has been selected. It should be noted that: the multiple user plane MBS session establishment requests received by the first user plane node at the same time may be sent by the same I-SMF (corresponding to the case where different control plane nodes select the same I-SMF), or may be sent by different I-SMFs (corresponding to the case where different control plane nodes select different I-SMFs). The technical scheme of the embodiment enables one user plane node to be selected as a child node of another user plane node only, and not to be selected as child nodes of a plurality of user plane nodes.

In one embodiment of the present application, if the first user plane node receives again a user plane MBS session establishment request for selecting the first user plane node as a child user plane node of other user plane nodes after feeding back the first user plane MBS session establishment response to the I-SMF, a feedback rejection message is fed back for the received again user plane MBS session establishment request to indicate that this user plane node has been selected. It should be noted that: the user plane MBS session establishment request received again by the first user plane node may be sent by other I-SMFs, or may be sent by an I-SMF that the first user plane node feeds back the first user plane MBS session establishment response, but the user plane MBS session establishment request received again is for selecting the first user plane node as a child user plane node of the other user plane nodes. The technical solution of this embodiment also enables one user plane node to be selected only as a child node of another user plane node, but not as child nodes of a plurality of user plane nodes.

Fig. 14B shows a flowchart of a communication method of a multicast broadcast service according to an embodiment of the present application, which may be performed by the first user plane node described above, and the communication method of the multicast broadcast service includes at least steps S1410 'to S1430', which are described in detail as follows:

in step S1410', a second user plane MBS session establishment request sent by the I-SMF is received, where the second user plane MBS session establishment request includes a second MBS IP multicast transmission address and a second C-TEID allocated by the first user plane node selected by the I-SMF.

In step S1420', a second user plane MBS session establishment response is fed back to the I-SMF, where the second user plane MBS session establishment response includes a third MBS IP multicast transmission address and a third C-TEID allocated by the second user plane node selected by the I-SMF, and the third MBS IP multicast transmission address is used for a sub-user plane node of the second user plane node to join a multicast transmission group corresponding to the third MBS IP multicast transmission address to receive MBS service data transmitted by the second user plane node in a multicast manner.

In step S1430', if the second user plane node supports receiving MBS service data sent by the first user plane node in a multicast manner, the second user plane node adds a multicast transmission group corresponding to the second MBS IP multicast transmission address to receive the MBS service data sent by the first user plane node in the multicast manner.

In an embodiment of the present application, if the second user plane node does not support receiving MBS service data sent by the first user plane node in a multicast manner but in a point-to-point manner, the second user plane node may allocate an F-TEID for receiving the MBS service data sent by the first user plane node in a point-to-point manner.

In an embodiment of the present application, after feeding back a second user plane MBS session establishment response to the I-SMF, the second user plane node may further receive a second user plane MBS session modification request sent by the I-SMF, where the second user plane MBS session modification request includes first F-TEID list information, where the first F-TEID list information includes F-TEIDs of sub-user plane nodes that do not support receiving, in a multicast manner and in a point-to-point manner, MBS service data of the sub-user plane nodes corresponding to the F-TEIDs included in the first F-TEID list information, and then the second user plane node may transmit, based on the first F-TEID list information, the MBS service data to the sub-user plane nodes corresponding to the F-TEIDs included in the first F-TEID list information in a point-to-point manner, and determine whether to send the service data to the sub-user plane nodes of the second user plane node in a multicast transmission manner at the same time according to the second user plane MBS session modification request. Please refer to the technical solutions of the foregoing embodiments, which are not described in detail.

In an embodiment of the application, if a second user plane node receives a user plane MBS session deletion request sent by an I-SMF, sending a user plane MBS session deletion response to the I-SMF; if the second user node has been added into the multicast transmission group corresponding to the second MBS IP multicast transmission address, the multicast transmission group corresponding to the second MBS IP multicast transmission address is exited after the user MBS session deleting request is received. The technical scheme of the embodiment is to delete the broken branches in the user plane MBS session transmission tree.

In an embodiment of the present application, if the second user plane node receives multiple user plane MBS session establishment requests, the second user plane node feeds back a user plane MBS session establishment response to one of the multiple user plane MBS session establishment requests, and feeds back a rejection message to other user plane MBS session establishment requests in the multiple user plane MBS session establishment requests to indicate that the user plane node has been selected. It should be noted that: the multiple user plane MBS session establishment requests received by the second user plane node at the same time may be sent by the same I-SMF (corresponding to the case where different control plane nodes select the same I-SMF), or may be sent by different I-SMFs (corresponding to the case where different control plane nodes select different I-SMFs). The technical scheme of the embodiment enables one user plane node to be selected as a child node of another user plane node only, and not to be selected as child nodes of a plurality of user plane nodes.

In an embodiment of the present application, if the second user plane node receives again the user plane MBS session establishment request for selecting the second user plane node as a child user plane node of other user plane nodes after feeding back the second user plane MBS session establishment response to the I-SMF, a feedback rejection message is fed back for the received again user plane MBS session establishment request to indicate that this user plane node has been selected. It should be noted that: the user plane MBS session establishment request received again by the second user plane node may be sent by other I-SMFs, or may be sent by an I-SMF that the second user plane node feeds back the first user plane MBS session establishment response, but the user plane MBS session establishment request received again is for selecting the second user plane node as a child user plane node of the other user plane node. The technical scheme of the embodiment also ensures that one user plane node can only be selected as a child node of another user plane node but not as child nodes of a plurality of user plane nodes.

The technical solution of the embodiment of the present application is described above from the perspective of I-SMF, I-th level control plane node, and middle user plane node, and details of implementation of the technical solution of the embodiment of the present application are described in detail below from the perspective of interaction of each entity.

In an embodiment of the present application, the MBS session transmission tree of 5G needs to ensure that only one parent user plane node of each user plane is required, but since the user plane is controlled by the control plane, there may be only one parent control plane node of the control plane, in this case, the child control plane nodes may provide different one or more child user plane nodes to different parent control plane nodes, that is, even if different parent user plane nodes correspond to the same parent control plane node, the child user plane nodes are also independent from each other.

If a plurality of sub-user plane nodes are allocated to one father control plane node, and some sub-user plane nodes of the plurality of sub-user plane nodes support receiving data transmitted based on a multicast mode, and some sub-user plane nodes do not support receiving data transmitted based on a multicast mode, but support receiving MBS service data in a point-to-point mode, the sub-user plane nodes which do not support receiving multicast transmission data can allocate an IP address + TEID (represented by F-TEID) of a GTP-U to transmit the MBS service data to the sub-user plane nodes in a point-to-point mode.

Specifically, fig. 15 illustrates an MBS communication method with Control Plane and User Plane separated according to an embodiment of the present application, where F-CP appearing in the following represents a false-Control Plane (parent Control Plane), S-CP represents a Son-Control Plane (child Control Plane), F-UP represents a false-User Plane (parent User Plane), and S-UP represents a Son-User Plane (child User Plane).

Referring to fig. 15, the method includes the following steps:

in step S1501, the F-CP1 receives an MBS Session start Request (i.e., nfcp _ mbssessuonstartrequest) sent by a parent control plane node of the F-CP1, where the MBS Session start Request includes TMGI (temporal Mobile Group Identity), MBS Session Duration (MBS Session Duration), MBS QFIs (QoS Flow Identifier), qoS Profile (QoS configuration), UP ID (the UP ID is an Identifier of a user plane node at the same level as the parent control plane node of the F-CP 1), MBS IP Multicast Distribution (MBS IP Multicast Distribution information), MBS Time to Transfer (MBS Service Data transmission Time), and MBS Service Area (MBS Service Area).

Wherein, the TMGI represents a temporary group identification of multicast or broadcast; the MBS Session Duration represents the time length of this MBS Session; MBS Time to Data Transfer represents the Time for MBS service Data to start sending; the QoS Profile includes 5QI (5G QoS identifier,5G QoS indicator), MFBR (Maximum Flow Bit Rate), GFBR (Guaranteed Flow Bit Rate), ARP (Allocation and Retention Priority), and the like; the MBS IP Multicast Distribution includes an IP Multicast transport address (the IP Multicast transport address is allocated by a user plane node (i.e. the user plane node identified by the aforementioned UP ID) in the same level as the parent control plane node of F-CP1, and is denoted as IP1 for the sake of distinction) and a C-TEID (for simplicity, the parent control plane nodes of F-CP1 and F-CP2 and the parent user plane nodes of F-UP11 and F-UP21 are not shown in fig. 15); the MBS Service Area is a Service Area when this MBS Service is a broadcast Service.

And step S1502, the F-CP1 determines to select one or more F-UPFs from the plurality of F-UPFs as the user plane nodes with the same level as the F-CP1 according to the information of the sub control plane nodes of the F-CP 1. In this embodiment, it is assumed that only one user plane node (denoted as F-UP 11) having the same level as that of F-CP1 is selected, then F-CP1 sends a user plane MBS session establishment Request (i.e., N4 mbssessing availability Request) to F-UP11, and F-UP11 feeds back a user plane MBS session establishment Response (i.e., N4 mbssessing availability Response) to F-CP 1.

In an embodiment of the present application, for MBS multicast service, the information of the sub-control plane node of F-CP1 is composed of MBS UE contexts; for the MBS broadcast service, the information of the child control plane node of the F-CP1 is provided by the parent control plane node of the F-CP1 or is configured by the network according to the service area. The information of the sub-control plane nodes of the F-CP1 comprises the number and the position information of the sub-control plane nodes of the F-CP1, and the like.

In an embodiment of the present application, the user plane MBS session establishment request sent by the F-CP1 to the selected F-UP11 may include PDR (Packet Detection Rule), QER (QoS Enforcement Rule), FAR (Forwarding Action Rule), MBS IP Multicast Distribution, allocation New MBS IP Multicast Distribution for Downlink Node, and an indication requesting to Allocate F-TEID. The user plane MBS session establishment response fed back by the F-UP11 comprises allocation MBS IP Multicast Distribution for Downlink node and F-TEID.

The PDR in the user plane MBS session establishment request comprises one or more MBS IP Multicast addresses + UDP ports to indicate one or more different MBS QoS flows; the QER contains MFBR, GFBR and DL Flow Level Marking (downstream Level mark) corresponding to the PDR; the MBS IP Multicast Distribution is the MBS IP Multicast Distribution corresponding to the TMGI, and is from the receiving, by the F-CP1, of the MBS session start request sent by the parent control plane node of the F-CP1, where the contained MBS IP Multicast transmission address is IP1.

The allocation New MBS IP Multicast Distribution for Downlink Node indication in the user plane MBS session establishment request is used to indicate that the F-UP11 has sub-user plane nodes, so the F-UP11 needs to Allocate a New MBS IP Multicast Distribution, the allocation of the New MBS IP Multicast Distribution for Downlink Node in the user plane MBS session establishment response includes the New MBS IP Multicast Distribution allocated by the F-UP11, and the New MBS IP Multicast Distribution includes a New IP Multicast transmission address (for the sake of distinction, the New IP Multicast transmission address is marked as IP 2) and C-TEID.

It should be noted that MBS IP Multicast Distribution is allocated to all child user plane nodes of each parent user plane node by each parent user plane node, and different parent user plane nodes may allocate different MBS IP Multicast distributions.

In addition, if according to the network configuration, the F-UP11 does not support receiving MBS service data transmitted in a multicast manner, but supports receiving MBS service data in a point-to-point manner, the user plane MBS session establishment request message sent by the F-CP1 includes an indication requesting to allocate an F-TEID, so as to request the F-UP11 to allocate an F-TEID for receiving MBS service data sent by a parent user plane node of the F-UP11 in a point-to-point manner, and after allocating the F-TEID, the F-UP11 carries the allocated F-TEID in a user plane MBS session establishment response.

If the user plane MBS session establishment request does not include an indication requesting allocation of the F-TEID, i.e. the F-CP1 does not make a decision, but the user plane node F-UP11 does not support receiving data transmitted based on a multicast mode, then the F-UP11 also needs to allocate an F-TEID, and carries the allocated F-TEID in the user plane MBS session establishment response.

Step S1503, if the F-UP11 supports receiving data transmitted based on a multicast mode, applies to join the multicast transmission group corresponding to the IP multicast transmission address IP1 to receive MBS service data sent by the parent user plane node of the F-UP 11.

In step S1504, the F-CP1 sends an MBS session start Request (i.e., nscp _ mbssessuonstart Request) to each sub-control plane node according to the information of the sub-control plane node of the F-CP1, that is, steps S1504 to S1508 are executed separately for each sub-control plane node, and in this embodiment, the example of sending the MBS session start Request to one sub-control plane node S-CP is described.

The MBS session start request sent by the F-CP1 to the S-CP of the sub-control plane node of the F-CP1 comprises the following parameters: TMGI, MBS Session Duration, MBS QFISs, qoS Profile, F-UP11ID, MBS IP Multicast Distribution, MBS Time to Data Transfer, MBS Service Area. The MBS IP Multicast Distribution in the MBS session start request sent by the F-CP1 is allocated in step S1502, and the IP Multicast transport address included therein is IP2.

After receiving the MBS session start request sent by F-CP1, the S-CP selects one or more S-UPs of F-UP11 from the plurality of S-UPs according to the information of the sub-control plane node of the S-CP, similar to step S1502, assuming that S-UP1 and S-UP2 are selected in this embodiment. Then step S1505a and step S1505b are performed, respectively.

In step S1505a, the S-CP sends the user plane MBS conversation establishment request to the selected S-UP1, and the S-UP1 feeds back the user plane MBS conversation establishment response to the S-CP.

In an embodiment of the present application, the user plane MBS session establishment request sent by the S-CP may also include PDR, QER, FAR, MBS IP Multicast Distribution, F-UP11ID, allocation New MBS IP Multicast Distribution for Downlink Node indication, indication requesting to Allocate F-TEID, and the like. The user plane MBS session establishment response fed back by the S-UP1 comprises allocation MBS IP multimedia Distribution for Downlink node and F-TEID.

The MBS IP Multicast Distribution in the user plane MBS session establishment request sent by the S-CP is from the MBS session start request received in step S1504, where the IP Multicast transmission address included in the MBS session start request is IP2. The indication of the allocation New MBS IP Multicast Distribution for Downlink Node in the user plane MBS session establishment request sent by the S-CP to the S-UP1 is used for indicating the S-UP1 to Allocate a New MBS IP Multicast Distribution so as to send MBS service data to the sub-user plane nodes of the S-UP1 in a Multicast transmission mode. The process specifically assigned by S-UP1 is described with reference to step S1502. Similarly, if S-UP1 does not support multicast transmission, one F-TEID may be assigned and also assigned by S-UP 1.

Step S1505b, the S-CP sends the user plane MBS conversation establishment request to the selected S-UP2, and the S-UP2 feeds back the user plane MBS conversation establishment response to the S-CP. The specific process is similar to step S1505a and will not be described again.

In step S1506, if S-UP1 and S-UP2 support receiving the data transmitted in the multicast mode, they respectively join the multicast transmission group corresponding to the IP multicast transmission address (i.e. IP 2) allocated by F-UP11 to receive the MBS service data sent by F-UP 11.

In step S1507, the S-CP transmits an MBS session start Response (i.e., nscp _ MBSSesserstartResponse) including the F-UP11ID to the F-CP 1.

If one of the S-UP1 and S-UP2 does not support receiving data transmitted by multicast, the MBS session start response sent by the S-CP to the F-CP1 includes List of F-TEID (for the sub-user plane node, it is hereinafter referred to as List of F-TEIDsup for convenience of distinction) and corresponds to F-UP11. The List of F-TEIDs contains F-TEIDs allocated by S-UP that does not support receiving multicast transmissions but supports receiving MBS service data using a point-to-point approach in S-UP1 and S-UP 2. If some S-UP of S-UP1 and S-UP2 supports receiving Multicast transmission, multicast Enable needs to be included in MBS session start response to indicate that F-UP11 needs to transmit MBS service data to the sub-user plane nodes of F-UP11 using Multicast transmission and point-to-point transmission technology at the same time.

Particularly, if the MBS session start response sent by the S-CP to the F-CP1 does not contain List of F-TEIDsup, it indicates that all the sub-user plane nodes selected by the S-CP support receiving the data transmitted based on the Multicast mode, so the MBS session start response does not need to carry the Multicast Enable identifier.

Particularly, if the MBS session start response sent by the S-CP to the F-CP1 includes List of F-TEIDsup but does not include Multicast Enable, it indicates that all the sub-user plane nodes selected by the S-CP do not support receiving data transmitted by Multicast, but support receiving MBS service data transmitted by point-to-point.

In particular, if the MBS session start response sent by the S-CP to the F-CP1 does not include List of F-TEIDsup and Multicast Enable is set to Disable, it indicates that the child control plane node S-CP does not allocate the corresponding child user plane node for F-UP11 (one possible reason is that the child user plane node to be selected has already allocated the parent user plane node, and at this time, the child user plane nodes cannot be selected). In this case, the child control plane node S-CP may also indicate by returning Failure Code through an MBS session start response.

It should be noted that, if only one of the sub-user plane nodes selected by the S-CP does not support receiving data transmitted in a multicast manner, the MBS session start response sent by the S-CP to the F-CP1 may not include the List of F-TEIDs, but only include the F-TEID allocated by the sub-user plane node.

In step S1508, if the MBS session start response in step S1507 includes F-UP11 ID and F-TEID parameters (e.g., F-TEID allocated by a certain S-UP, or List of F-TEIDsup corresponding to some S-UP), F-CP1 sends a user plane MBS session modification Request (i.e., N4 MBSSationModification Request) to F-UP11, and F-UP11 feeds back the user plane MBS session modification response to F-CP 1. Wherein, the user plane MBS conversation amending request comprises List of F-TEIDsup corresponding to S-UP which does not support receiving multicast transmission but supports receiving MBS service data in a point-to-point mode, and the F-UP11 is instructed to increase and use the point-to-point mode to respectively transmit the MBS service data to the S-UP which does not support receiving multicast transmission but supports receiving MBS service data in the point-to-point mode. If the MBS session start response in step S1507 does not include an indication of Multicast Enable, it indicates that F-UP11 no longer uses the Multicast transmission scheme. If the MBS session start response in step S1507 includes the Multicast Enable indication, the F-UP11 is instructed to use Multicast transmission and peer-to-peer transmission simultaneously.

It should be noted that: if the MBS session start response in step S1507 only contains one F-TEID and F-UP11 does not know the specific number of sub-user plane nodes of F-UP11, F-UP11 may transmit MBS service data to S-UP corresponding to this F-TEID only in a point-to-point manner; while the F-UP11 may simultaneously transmit MBS service data to other S-UPs using the multicast transport address (i.e., IP 2) according to the user-plane MBS session modification request in step S1508.

If the MBS session start response in step S1507 does not include the F-TEID and Multicast Enable is not set to Disable, it indicates that F-UP11 continues to use the Multicast transmission, at which point step S1508 does not need to be performed.

In step S1509, after performing steps S1504 to S1508 for each child control plane node, the F-CP1 transmits an MBS session start Response (i.e., nfcp _ mbssessuonstart Response) to the parent control plane node of the F-CP1 according to the MBS session start responses fed back by all the child control plane nodes.

Similar to step S1507, the MBS session start response returned by F-CP1 to the F-CP1 parent control plane node contains the UP ID (which is the identity of the user plane node at the same level as the F-CP1 parent control plane node) and possibly also the List of F-TEIDs (for the sake of distinction, it is denoted as List of F-TEIDfup), and since F-CP1 selects only one user plane node F-UP11 at the same level, if the MBS session start response returned by F-CP1 to the F-CP1 parent control plane node contains List of F-TEIDfup, it also contains only the F-TEID allocated by F-UP 11.

It should be noted that, in this embodiment, since the F-CP1 only selects one peer user plane node F-UP11, if the MBS session start response returned by the F-CP1 to the parent control plane node of the F-CP1 does not include the F-TEID allocated by the F-UP11, in this case, it indicates that the F-UP11 supports receiving data transmitted in a Multicast manner, and at this time, the MBS session start response returned by the F-CP1 to the parent control plane node of the F-CP1 does not need to include Multicast Enable; if the MBS session start response replied by the F-CP1 to the parent control plane node of the F-CP1 contains the F-TEID distributed by the F-UP11, the F-UP11 does not support receiving the data transmitted based on the Multicast mode, in this case, the MBS session start response replied by the F-CP1 to the parent control plane node of the F-CP1 does not need to contain Multicast Enable because the F-CP1 only has one user plane node F-UP11 of the same level.

Wherein, steps S1501 to S1509 are the processing procedure after the F-CP1 receives the MBS session start request transmitted by the parent control plane node of the F-CP1, in which the F-CP1 selects one user plane node F-UP11 of the same level, and its child control plane node S-CP selects two child user plane nodes S-UP1 and S-UP2 of the same level as the S-CP.

With continued reference to FIG. 15, the method further includes the following steps:

in step S1510, the F-CP2 receives an MBS Session start request sent by the parent control plane node of the F-CP2, where the MBS Session start request includes TMGI, MBS Session Duration, MBS QFIs, qoS Profile, UPx ID, MBS IP Multicast Distribution, MBS Time to Data Transfer, and MBS Service Area. For the purpose of distinction, the meaning of the specific parameters refers to the description in step S1501, and the IP Multicast transmission address included in the MBS IP Multicast Distribution in the MBS session start request received by the F-CP2 may be denoted as IPx.

In step S1511, the F-CP2 determines to select one or more F-UPFs from the plurality of F-UPFs as the user plane nodes at the same level as the F-CP2 according to the information of the sub-control plane nodes of the F-CP 2. In this embodiment, it is assumed that only one user plane node F-UP21 with the same level as F-CP2 is selected, then the F-CP2 sends a user plane MBS session establishment request to the F-UP21, and the F-UP21 feeds back a user plane MBS session establishment response to the F-CP 2.

For a detailed description, referring to the related contents of the foregoing step S1502, similar to step S1502, the F-UP21 allocates a new IP multicast transport address (denoted as IP3 for the sake of distinction) through the interaction between the user plane MBS session establishment request and the user plane MBS session establishment response between the F-CP2 and the F-UP 21.

In addition, similarly, if the F-UP21 does not support receiving data transmitted based on multicast mode, the F-UP21 allocates an F-TEID for receiving MBS service data in point-to-point mode, and carries the allocated F-TEID in the user plane MBS session establishment response.

Step S1512, if the F-UP21 supports receiving the data transmitted in the multicast mode, applies to join the multicast transmission group corresponding to the IP multicast transmission address IPx to receive the MBS service data sent by the parent user plane node of the F-UP 21.

In step S1513, the F-CP2 sends the MBS session start request to each sub-control plane sub-node according to the information of the sub-control plane node of the F-CP2, that is, steps S1513 to S1517 are executed separately for each sub-control plane node, in this embodiment, the sending to one sub-control plane node S-CP is taken as an example for explanation.

Similarly, the MBS session start request sent by the F-CP2 to the S-CP serving as the child control plane node of the F-CP2 also includes MBS IP Multicast Distribution, and the MBS IP Multicast Distribution is allocated in step S1511, and the corresponding user plane node identifier is F-UP21 ID, where the included IP Multicast transmission address is IP3.

It should be noted that: step S1513 and step S1504 have no precedence relationship therebetween, and they may be steps executed by the F-CP2 and the F-CP1 in parallel, respectively.

After receiving the MBS session start request sent by the F-CP2, the S-CP selects one or more S-UPs for the F-UP21 from the plurality of S-UPs according to the information of the sub-control plane node of the S-CP, which is assumed to select S-UP3 and S-UP4, and then performs step S1514a and step S1514b, respectively, similar to the above steps.

It should be noted that S-CP is selected for F-UP21 differently from S-CP selected for F-UP 11. In other words, in the embodiments of the present application, a child control plane node may have multiple parent control plane nodes on the control plane, for example, the child control plane node S-CP has two parent control plane nodes F-CP1 and F-CP2, but a child user plane node is not allowed to have multiple parent user plane nodes, so that when a child user plane node already has a parent user plane node, it is not able to participate in the selection of the child user plane node. Therefore, S-CP can only select S-UP3 and S-UP4 for F-UP21, while S-UP1 and S-UP2 have already been selected as the sub-user plane nodes of F-UP11, and therefore S-CP can no longer select S-UP1 and S-UP2 as the sub-user plane nodes of F-UP 21.

Step S1514a, S-CP sends user plane MBS conversation establishment request to the selected S-UP3, S-UP3 feeds back user plane MBS conversation establishment response to S-CP. Step S1514b, S-CP sends user plane MBS conversation establishment request to the selected S-UP4, S-UP4 feeds back user plane MBS conversation establishment response to S-CP. The specific process is similar to step S1505a and will not be described again.

In step S1515, if S-UP3 and S-UP4 support receiving the data transmitted based on the multicast mode, they are respectively added into the multicast transmission group corresponding to the IP multicast transmission address (i.e. IP 3) allocated by F-UP21 to receive the MBS service data sent by F-UP 21.

In step S1516, the S-CP sends an MBS session start response to the F-CP2, and the MBS session start response includes the F-UP21 ID. The detailed description of this step is similar to the step S1507, and is not repeated.

Step S1517, F-CP2 sends user MBS conversation amendment request to F-UP21, F-UP21 feeds back user MBS conversation amendment response to F-CP 2. The detailed description of this step is similar to that of step S1508, and is not repeated here.

In step S1518, after performing steps S1513 to S1517 for each child control plane, the F-CP2 sends an MBS session start response to the parent control plane node of the F-CP2 according to the MBS session start response fed back by all the child control planes. The detailed description of this step is similar to the step S1509 and is not repeated.

Wherein, steps S1510 to S1518 are the processing procedure after the F-CP2 receives the MBS session start request transmitted from the parent control plane node of the F-CP2, in which the F-CP2 selects the user plane node F-UP21 of one peer, and the child control plane node S-CP of the F-CP2 selects the two child user plane nodes S-UP3 and S-UP4 of the same peer as the S-CP.

As can be seen from steps S1501 to S1518, in the embodiment of the present application, the sub-control plane node S-CP has multiple parent control plane nodes F-CP1 and F-CP2, and the sub-user plane node S-UP controlled by the S-CP has only one parent user plane node.

In addition, the message in step S1501 and the message in step S1510 may be issued in parallel, and thus, steps S1501 to S1509 and steps S1510 to S1518 may be executed in parallel. Thus, in the process of establishing the user plane MBS session, there may exist a user plane node simultaneously sent the user plane MBS session establishment request message by two control plane nodes, or a user plane MBS session establishment request message sent by another control plane node is received after being selected by a control plane node. If a user plane node receives a user plane MBS session establishment request message sent by two control plane nodes (certainly, there may be more, and two are exemplified here) at the same time, the user plane node may normally respond to the user plane MBS session establishment request sent by one of the control plane nodes in a user plane MBS session establishment response message, and Reject (Reject) another control plane node in another user plane MBS session establishment response message to indicate that the user plane node has been selected. If a user plane node has a father user plane node through a control plane node and receives a user plane MBS conversation establishing request message sent by another control plane node, the other control plane node is objected in another user plane MBS conversation establishing response message to indicate that the user plane node has been selected.

After the establishment of the MBS session transmission tree is completed, the following steps may be performed:

in step S1519a, the F-UP11 receives the downlink MBS service data sent by the parent user plane node of the F-UP 11. And then transmits the received downlink MBS service data to S-UP1 and S-UP2 through step S1520 a.

It should be noted that: for each user plane node with a parent user plane node, the MBS service data needs to be received in the multicast transmission mode or the point-to-point transmission mode determined in the previous step. For example, for S-UP1 and S-UP2, if it is determined that only the multicast transmission mode is adopted, S-UP1 and S-UP2 receive MBS service data sent by F-UP11 through the multicast transmission mode; and if the point-to-point transmission mode is only adopted, the S-UP1 and the S-UP2 respectively receive the MBS service data sent by the F-UP11 through the point-to-point transmission mode.

For each user plane node with sub user plane nodes, it needs to transmit MBS service data to each sub user plane node in the multicast transmission mode or point-to-point transmission mode determined in the previous step. For example, for F-UP11, if it is determined that only the multicast transmission mode is adopted, F-UP11 transmits MBS service data to all sub-user plane nodes of F-UP11 (i.e., S-UP1 and S-UP2 in this embodiment) in the multicast mode; if it is determined that only the point-to-point transmission mode is adopted, F-UP11 transmits MBS service data to each sub-user plane node (i.e., S-UP1 and S-UP2 in this embodiment) of F-UP11 in the point-to-point transmission mode.

In step S1519b, the F-UP21 receives the downlink MBS service data sent by the parent user plane node of the F-UP 21. And then transmits the received downlink MBS service data to S-UP3 and S-UP4 through step S1520 b. Each user plane node transmits MBS service data in the multicast transmission mode or the point-to-point transmission mode determined in the previous step, and simultaneously each user plane node receives the MBS service data in the multicast transmission mode or the point-to-point transmission mode determined in the previous step.

In the embodiment shown in fig. 15, the MBS session start request sent by the parent control plane node to the child control plane node only contains information of one parent user plane node, and in another embodiment of the present application, as described below with reference to fig. 16, the MBS session start request sent by the parent control plane node to the child control plane node may contain information of multiple parent user plane nodes.

Specifically, fig. 16 illustrates an MBS communication method with Control Plane and User Plane separated according to an embodiment of the present application, and similarly, F-CP appearing in the following represents a false-Control Plane (parent Control Plane), S-CP represents a Son-Control Plane (child Control Plane), F-UP represents a false-User Plane (parent User Plane), and S-UP represents a Son-User Plane (child User Plane).

Referring to fig. 16, the method includes the following steps:

in step S1601, the F-CP1 receives an MBS session start request sent by the parent control plane node of the F-CP 1. The specific process is similar to step S1501 and will not be described again. Wherein, the IP Multicast transmission address contained in the MBS IP Multicast Distribution in the MBS session start request is recorded as IP1.

After receiving the MBS session start request sent by the parent control plane node of the F-CP1, the F-CP1 may determine to select one or more F-UPFs from the multiple F-UPFs as user plane nodes of the same level as the F-CP1 according to the information of the child control plane nodes of the F-CP1, where in this embodiment, it is assumed that two user plane nodes are selected and denoted as F-UP11 and F-UP12. Then, step S1602a and step S1602b are respectively performed.

In step S1602a, the F-CP1 sends a user plane MBS session establishment request to the F-UP11, and the F-UP11 feeds back a user plane MBS session establishment response to the F-CP 1. The process is similar to the process of step S1502 in the foregoing embodiment, and is not described again, where the IP multicast transport address allocated by F-UP11 in step S1602a is denoted as IP2.

Step S1602b, F-CP1 sends user plane MBS session establishment request to F-UP12, F-UP12 feeds back user plane MBS session establishment response to F-CP 1. The process is similar to the process of step S1502 in the foregoing embodiment, and is not described again, wherein the IP multicast transport address allocated by the F-UP12 in step S1602b is denoted as IP3.

Step S1603, if the F-UP11 and the F-UP12 support to receive the data transmitted based on the multicast mode, applying for joining the multicast transmission group corresponding to the IP multicast transmission address IP1 to receive MBS service data sent by the father user plane node of the F-UP11 and the F-UP 12.

In step S1604, the F-CP1 sends an MBS session start request to each sub-control plane sub-node according to the information of the sub-control plane node of the F-CP1, that is, steps S1604 to S1608 are executed for each sub-control plane node separately, and in this embodiment, the sending to one sub-control plane node S-CP is taken as an example for explanation.

The MBS session start request sent by the F-CP1 to the S-CP of the sub-control plane node of the F-CP1 comprises the following parameters: TMGI, MBS Session Duration, MBS QFISs, qoS Profile, MBS Time to Data Transfer, list of { F-UP ID, MBS transmission information }, MBS Service Area. The MBS transmission information is MBS IP Multicast Distribution (C-TEID). In this embodiment, since F-CP1 selects two user plane nodes F-UP11 and F-UP12 with the same level as F-CP1, the List of { F-UP ID, MBS transmission information } includes MBS IP Multicast Distribution corresponding to F-UP11 ID and F-UP11 ID, and MBS IP Multicast Distribution corresponding to F-UP12 ID and F-UP12 ID. MBS IP Multicast Distribution corresponding to the F-UP11 ID is distributed by the F-UP11, wherein the contained IP Multicast transmission address is IP2; the MBS IP Multicast Distribution corresponding to the F-UP12 ID is distributed by the F-UP12, and the IP Multicast transmission address contained in the MBS IP Multicast Distribution is IP3.

It should be noted that: the IP multicast transport address IP3 assigned by F-UP12 and the IP multicast transport address IP2 assigned by F-UP11 cannot be the same, but the assigned C-TEID may be the same.

After receiving the MBS session start request sent by F-CP1, similar to step S1502, the S-CP selects one or more S-UPs for F-UP11 and one or more S-UPs for F-UP12 from the plurality of S-UPs according to the information of the sub-control plane nodes of the S-CP, in this embodiment, it is assumed that S-UP11 and S-UP12 are selected for F-UP11, and S-UP21 and S-UP22 are selected for F-UP12, i.e. different sub-user plane nodes are selected for F-UP11 and F-UP 12. Then step S1605a and step S1605b are performed, respectively.

In step S1605a, S-CP sends user plane MBS session establishment request to selected S-UP11 and S-UP12 respectively, where the user plane MBS session establishment request includes IP multicast transport address IP2 allocated by F-UP11, and S-UP11 and S-UP12 respectively feed back user plane MBS session establishment response to S-CP (S-UP 11 and S-UP12 are drawn together in fig. 16 to save layout). The specific process is similar to step S1505a and will not be described again.

In step S1605b, the S-CP sends user plane MBS session establishment request to the selected S-UP21 and S-UP22, where the user plane MBS session establishment request includes IP multicast transport address IP3 allocated by F-UP12, and S-UP21 and S-UP22 respectively feed back user plane MBS session establishment response to the S-CP (S-UP 21 and S-UP22 are drawn together in fig. 16 to save layout). The specific process is similar to step S1505a and will not be described again.

In step S1606a, if S-UP11 and S-UP12 support receiving data transmitted in a multicast manner, they respectively join the multicast transmission group corresponding to the IP multicast transmission address (i.e. IP 2) allocated by F-UP11 to receive MBS service data sent by F-UP 11.

In step S1606b, if S-UP21 and S-UP22 support receiving data transmitted in a multicast manner, they respectively join the multicast transmission group corresponding to the IP multicast transmission address (i.e. IP 3) allocated by F-UP12 to receive MBS service data sent by F-UP 12.

In step S1607, the S-CP sends an MBS session start response to the F-CP 1. If there is S-UP that does not support receiving data transmitted by Multicast, the MBS session start response includes the S-UP allocated F-TEID and corresponds to F-UP, thereby forming a List of { F-UP ID, list of F-TEID, multicast Enable }. In this embodiment, list of { F-UP ID, list of F-TEIDsup, multicast Enable } contains List of F-TEIDsup and Multicast Enable for F-UP11, and List of F-TEIDsup and Multicast Enable for F-UP 12.

Similar to step S1507, since some S-UPs support receiving data transmitted based on multicast and some other S-UPs do not support receiving data transmitted based on multicast, this List F-TEIDsup corresponds only to those S-UPs that do not support receiving multicast transmission but support receiving MBS service data using point-to-point. Therefore, when all S-UPs of an F-UP support receiving data transmitted based on multicast, the List of F-TEIDsup corresponding to the F-UP is not available, and other descriptions refer to the related contents of step S1507.

In addition, when the S-CP decides not to assign any sub-user plane node to one/some F-UP ID (S), the Multicast Enable corresponding to the/these F-UP ID (S) can be set to Disable. Of course, failed List { F-UP } may also be employed in the MBS session start response to indicate parent user plane nodes to which no child user plane nodes are allocated.

In step S1608a, F-CP1 sends a user plane MBS session modification request to F-UP11 according to List of { F-UP ID, list of F-TEIDsup, multicast Enable } contained in the MBS session start response, and F-UP11 feeds back the user plane MBS session modification response to F-CP 1. The detailed description of this step is similar to that of step S1508, and is not repeated herein.

In step S1608b, F-CP1 sends a user plane MBS session modification request to F-UP12 according to the List of { F-UP ID, list of F-TEIDsup, multicast Enable } contained in the MBS session start response, and F-UP12 feeds back the user plane MBS session modification response to F-CP 1. The detailed description of this step is similar to that of step S1508, and is not repeated here.

In step S1609, after performing steps S1604 to S1608 for each of the child control planes, the F-CP1 sends an MBS session start response to the parent control plane node of the F-CP1 according to the MBS session start response fed back by all the child control planes.

Since F-CP1 selects two user plane nodes F-UP11 and F-UP12 of the same level as F-CP1, if one of F-UP11 and F-UP12 does not support receiving data transmitted by multicast, the MBS session start response returned by F-CP1 to the parent control plane node of F-CP1 contains List of F-TEID (for the sake of distinction, it is for the parent user plane node, and it is hereinafter referred to as List of F-TEIDfup), and corresponds to the UP ID of the parent user plane node of F-UP11 and F-UP 12. The List of F-TEIDfup contains F-TEIDs allocated by F-UP that does not support receiving multicast transmission but supports receiving MBS traffic data in a point-to-point manner in F-UP11 and F-UP 12. If some of the F-UPs 11 and F-UP12 support receiving Multicast-based data, multicast Enable needs to be included in the MBS session start response to indicate that the parent user plane nodes of F-UP11 and F-UP12 need to transmit MBS service data to F-UP11 and F-UP12 using Multicast transmission and point-to-point transmission technologies at the same time.

Particularly, if the MBS session start response returned by the F-CP1 to the parent control plane node of the F-CP1 does not contain List of F-teidfop, it indicates that all the user plane nodes of the same level as the F-CP1 selected by the F-CP1 support receiving the data transmitted in the Multicast mode, and therefore the MBS session start response does not need to carry the Multicast Enable identifier.

Particularly, if the MBS session start response returned by the F-CP1 to the parent control plane node of the F-CP1 includes List of F-teidfip, but does not include the identifier of Multicast Enable, it indicates that all the user plane nodes at the same level as the F-CP1 selected by the F-CP1 do not support receiving the data transmitted by Multicast, but support receiving the MBS service data transmitted by point-to-point.

In particular, if the MBS session start response returned by F-CP1 to the F-CP1 parent control plane node does not contain the List of F-TEIDfup, and the Multicast Enable is set to Disable, it indicates that F-CP1 has not selected the user plane node at the same level as F-CP 1. In this case, the F-CP1 may also return a Failure Code by MBS session start response.

It should be noted that if only one of the user plane nodes at the same level as F-CP1 selected by F-CP1 does not support receiving data transmitted in a multicast mode, the MBS session start response may not include List of F-TEIDfup, but only include the F-TEID allocated by the user plane node that does not support receiving multicast transmission but supports receiving MBS service data in a point-to-point mode.

Steps S1601 to S1609 are processing procedures after the F-CP1 receives the MBS session start request sent by the parent control plane node of the F-CP1, in which the F-CP1 selects two user plane nodes F-UP11 and F-UP12 at the same level as the F-CP1, and the child control plane node S-CP of the F-CP1 selects two child user plane nodes S-UP11 and S-UP12 at the same level as the S-CP for the F-UP11, and selects two child user plane nodes S-UP21 and S-UP22 at the same level as the S-CP for the F-UP 12.

With continued reference to FIG. 16, the method further includes the following steps:

step S1610, the F-CP2 receives an MBS Session start request sent by the father control surface node of the F-CP2, wherein the MBS Session start request comprises TMGI, MBS Session Duration, MBS QFIs, qoS Profile, UPx ID, MBS IP Multicast Distribution, MBS Time to Data Transfer, and MBS Service Area. Wherein, the meaning of the specific parameter refers to the description in the foregoing step S1501, and for the sake of distinction, the IP Multicast transmission address included in the MBS IP Multicast Distribution in the MBS session start request received by the F-CP2 may be denoted as IPx.

In step S1611, the F-CP2 determines to select one or more F-UPFs from the plurality of F-UPFs as the user plane nodes having the same level as the F-CP2 according to the information of the sub-control plane nodes of the F-CP 2. In this embodiment, it is assumed that only one user plane node F-UP21 with the same level as F-CP2 is selected, then the F-CP2 sends a user plane MBS session establishment request to the F-UP21, and the F-UP21 feeds back a user plane MBS session establishment response to the F-CP 2.

For a detailed description, referring to the related contents of the foregoing step S1502, similar to step S1502, the F-UP21 allocates a new IP multicast transport address (denoted as IP4 for the sake of distinction) through the interaction between the user plane MBS session establishment request and the user plane MBS session establishment response between the F-CP2 and the F-UP 21.

In addition, similarly, if F-UP21 does not support receiving data transmitted based on multicast mode, F-UP21 allocates a F-TEID for receiving MBS service data in point-to-point mode, and carries the allocated F-TEID in the user plane MBS session establishment response.

Step S1612, if the F-UP21 supports receiving the data transmitted based on the multicast mode, applies to join the multicast transmission group corresponding to the IP multicast transmission address IPx to receive the MBS service data sent by the parent user plane node of the F-UP 21.

In step S1613, the F-CP2 sends an MBS session start request to each sub-control plane node according to the information of the sub-control plane node of the F-CP2, that is, step S1613 to step S1617 are executed separately for each sub-control plane node, and in this embodiment, the sending to one sub-control plane node S-CP is taken as an example for explanation.

Similarly, the MBS session start request sent by the F-CP2 to the S-CP sub-control plane node of the F-CP2 also includes the MBS IP Multicast Distribution, and the MBS IP Multicast Distribution is allocated in step S1611, and the corresponding user plane node identifier is F-UP21 ID, and the IP Multicast transmission address included in the Distribution is IP4.

It should be noted that: there is no precedence relationship between step S1613 and step S1604, and they may be steps executed by F-CP2 and F-CP1 respectively in parallel.

After the S-CP receives the MBS session start request sent by the F-CP2, the S-CP selects one or more S-UPs for the F-UP21 from the plurality of S-UPs according to the information of the sub control plane node of the S-CP, assuming that S-UPs 31 and S-UP32 are selected, similar to the above steps, and then performs step S1614.

It should be noted that S-CP selected for F-UP21 is different from S-CP selected for F-UP11 and F-UP 12. In other words, in the embodiments of the present application, a child control plane node may have multiple parent control plane nodes on the control plane, for example, the child control plane node S-CP has two parent control plane nodes F-CP1 and F-CP2, but a child user plane node is not allowed to have multiple parent user plane nodes, so that when a child user plane node already has a parent user plane node, it is not able to participate in the selection of the child user plane node.

In step S1614, S-CP sends user plane MBS conversation establishing request to selected S-UP31 and S-UP32, and S-UP31 and S-UP32 feed back user plane MBS conversation establishing response to S-CP. The specific process is similar to step S1505a and will not be described again.

In step S1615, if S-UP31 and S-UP32 support receiving data transmitted in a multicast mode, they respectively join the multicast transmission group corresponding to the IP multicast transmission address (i.e. IP 4) allocated by F-UP21 to receive MBS service data sent by F-UP 21.

In step S1616, the S-CP sends an MBS session start response to the F-CP2, wherein the MBS session start response includes the F-UP21 ID. The detailed description of this step is similar to the step S1507, and is not repeated.

In step S1617, F-CP2 sends a user plane MBS session modification request to F-UP21, and F-UP21 feeds back a user plane MBS session modification response to F-CP 2. The detailed description of this step is similar to that of step S1508, and is not repeated here.

In step S1618, after performing steps S1613 to S1617 for each child control plane, the F-CP2 transmits an MBS session start response to the parent control plane node of the F-CP2 according to the MBS session start response fed back by all the child control planes. The detailed description of this step is similar to the step S1509 and is not repeated.

Wherein, steps S1610 to S1618 are the processing procedure after the F-CP2 receives the MBS session start request sent by the parent control plane node of the F-CP2, in which the F-CP2 selects one user plane node F-UP21 at the same level as the F-CP2, and the child control plane node S-CP of the F-CP2 selects two child user plane nodes S-UP31 and S-UP32 at the same level as the S-CP.

As can be seen from steps S1601 to S1618, in the embodiment of the present application, the sub-control plane node S-CP has multiple parent control plane nodes F-CP1 and F-CP2, and the sub-user plane node S-UP controlled by the S-CP has only one parent user plane node.

In addition, the message in step S1601 and the message in step S1610 may be issued in parallel, and thus steps S1601 to S1609 and steps S1610 to S1618 may be executed in parallel. Thus, in the process of establishing the user plane MBS session, there may exist a user plane node simultaneously sent the user plane MBS session establishment request message by two control plane nodes, or a user plane MBS session establishment request message sent by another control plane node is received after being selected by a control plane node. If a user plane node receives a user plane MBS session establishment request message sent by two control plane nodes (certainly, there may be more, and two are exemplified here) at the same time, the user plane node may normally respond to the user plane MBS session establishment request sent by one of the control plane nodes in a user plane MBS session establishment response message, and Reject (Reject) another control plane node in another user plane MBS session establishment response message to indicate that the user plane node has been selected. If a user plane node has a father user plane node through a control plane node and receives a user plane MBS conversation establishing request message sent by another control plane node, the other control plane node is objected in another user plane MBS conversation establishing response message to indicate that the user plane node has been selected.

After the establishment of the MBS session transmission tree is completed, the following steps may be performed:

in step S1619a, the F-UP11 receives the downlink MBS service data sent by the parent user plane node of the F-UP 11. And then transmits the received downlink MBS service data to S-UP11 and S-UP12 through step S1620 a. Each user plane node transmits MBS service data in the multicast transmission mode or the point-to-point transmission mode determined in the previous step, and simultaneously each user plane node receives MBS service data in the multicast transmission mode or the point-to-point transmission mode determined in the previous step.

In step S1619b, the F-UP12 receives the downlink MBS service data sent by the parent user plane node of the F-UP 12. And then transmits the received downlink MBS service data to the S-UP21 and S-UP22 through step S1620 b. Each user plane node transmits MBS service data in the multicast transmission mode or the point-to-point transmission mode determined in the previous step, and simultaneously each user plane node receives the MBS service data in the multicast transmission mode or the point-to-point transmission mode determined in the previous step.

In step S1619c, the F-UP21 receives the downlink MBS service data sent by the parent user plane node of the F-UP 21. And then transmits the received downlink MBS service data to the S-UP31 and S-UP32 through step S1620 c. Each user plane node transmits MBS service data in the multicast transmission mode or the point-to-point transmission mode determined in the previous step, and simultaneously each user plane node receives the MBS service data in the multicast transmission mode or the point-to-point transmission mode determined in the previous step.

In the embodiment shown in fig. 16, the MBS session start request sent by a parent control plane node to a child control plane node contains information of multiple parent user plane nodes. Alternatively, in a 5G system, the NR (New Radio) base station (gNB) may be a control plane separated from the user plane, i.e., a gNB-CU (Centralized Unit) may serve as a sub-control plane node, a gNB-DU (Distributed Unit) may serve as a sub-user plane node, and the control plane of one base station may control the user plane of one or more base stations. As shown in fig. 17, the gNB in the NG-RAN is connected to a 5GC (5 g Core network ) through an NG interface, the gNB in the NG-RAN may be separated from a control plane and a user plane, an interface between the base station control plane (i.e., gNB-CU) and the base station user plane (i.e., gNB-DU) may be an F1 interface, and an interface between the gnbs may be an Xn-C interface.

In one embodiment of the application, the embodiment shown in fig. 18 can be obtained after applying the gNB-CU and the gNB-DU to the embodiment shown in fig. 16, since the network node SMF or MB-SMF is not able to communicate directly with the NR base station, and thus AMF is introduced for interaction.

Referring to fig. 18, the following steps may be included:

In step S1801, the F-CP1 receives the MBS session start request sent by the parent control plane node of the F-CP 1. The specific process is similar to step S1501 and will not be described again. Wherein, the IP Multicast transmission address contained in the MBS IP Multicast Distribution in the MBS session start request is marked as IP1.

After receiving the MBS session start request sent by the parent control plane node of the F-CP1, the F-CP1 may determine to select one or more user plane nodes from the multiple F-UPFs as the user plane nodes at the same level as the F-CP1 according to the information (such as location, number, and the like) of the gNB corresponding to the F-CP1, where in this embodiment, it is assumed that two user plane nodes are selected and denoted as F-UP11 and F-UP12. Then step S1802a and step S1802b are performed, respectively.

In step S1802a, F-CP1 sends a user plane MBS session establishment request to F-UP11, and F-UP11 feeds back a user plane MBS session establishment response to F-CP 1. The process is similar to the process of step S1502 in the foregoing embodiment, and is not described again, where the IP multicast transmission address allocated by F-UP11 in step S1802a is denoted as IP2.

In step S1802b, F-CP1 sends a request for establishing user plane MBS session to F-UP12, and F-UP12 feeds back a response for establishing user plane MBS session to F-CP 1. The process is similar to the process of step S1502 in the foregoing embodiment, and is not described again, where the IP multicast transport address allocated by F-UP12 in step S1802b is denoted as IP3.

Step S1803, if the F-UP11 and the F-UP12 support receiving data transmitted based on a multicast mode, apply for joining in a multicast transmission group corresponding to the IP multicast transmission address IP1 to receive MBS service data sent by the parent user plane node of the F-UP11 and the F-UP 12.

At step S1804a, the F-CP1 sends an information transfer message (i.e., namf _ Communication _ nonen 2 MessageTransfer) to the AMF.

The F-CP1 sends an information transfer message to the AMF containing the following parameters: RAN ID, N2 MBS Session Container. Wherein, the N2 MBS Session Container includes (N2 MBS Session Start Request (TMGI, MBS QFIs, qoS Profile, list of { F-UP ID, MBS transmission information })). The MBS transmission information is MBS IP Multicast Distribution address (C-TEID). In this embodiment, since F-CP1 selects two user plane nodes F-UP11 and F-UP12 with the same level as F-CP1, the List of { F-UP ID, MBS transmission information } includes MBS IP Multicast Distribution corresponding to F-UP11 ID and F-UP11 ID, and MBS IP Multicast Distribution corresponding to F-UP12 ID and F-UP12 ID. MBS IP Multicast Distribution corresponding to the F-UP11 ID is distributed by the F-UP11, wherein the contained IP Multicast transmission address is IP2; the MBS IP Multicast Distribution corresponding to the F-UP12 ID is allocated by the F-UP12, and the IP Multicast transmission address contained in the MBS is IP3.

It should be noted that: the IP multicast transport address IP3 assigned by F-UP12 and the IP multicast transport address IP2 assigned by F-UP11 cannot be the same, but the assigned C-TEID may be the same.

The MBS Session container contained in the information delivery message sent by F-CP1 to AMF indicates that the AMF is to send the relevant content of N2 MBS Session Start Request (TMGI, MBS QFIs, qoS Profile, list of { F-UP ID, MBS transmission information }) to the gNB identified by RAN ID. When a plurality of RAN IDs are recorded in the MBS Session Context in the F-CP1, the subsequent steps S1804b to S1808b are respectively performed for the gnbs identified by each RAN ID.

In step S1804b, the AMF sends an MBS session start request to the corresponding gNB-CU according to the RAN ID contained in the information transfer message in step S1804a, including the parameters in step S1804a, i.e. including TMGI, MBS QFIs, qoS Profile, list of { F-UP ID, MBS transmission information }.

After the gNB-CU receives the MBS session start request sent by the AMF, the gNB-CU selects one or more gNB-DUs for F-UP11 and F-UP12 from the multiple gNB-DUs according to the number and position (for MBS multimedia Service) of the registered MBS multimedia Service UEs or MBS Broadcast Service Area (for MBS Broadcast Service), respectively. In this embodiment, it is assumed that a gNB-DU11 and a gNB-DU12 are selected for F-UP11, and a gNB-DU21 and a gNB-DU22 are selected for F-UP12, i.e., different gNB-DUs are selected for F-UP11 and F-UP 12. Then, step S1805a and step S1805b are performed, respectively.

In step S1805a, the gNB-CU sends a user plane MBS Session Establishment Request (i.e., F1 MBS Session Establishment Request) to each of the selected gNB-DU11 and gNB-DU12, where the user plane MBS Session Establishment Request includes the IP multicast transmission address IP2 allocated by F-UP11, and the gNB-DU11 and gNB-DU12 respectively feed back a user plane MBS Session Establishment response to the gNB-CU (to save the layout, the gNB-DU11 and the gNB-DU12 are drawn together in fig. 18). The specific process is similar to the interaction process between S-CP and S-UP in step S1505a, and is not described again.

In step S1805b, the gNB-CU sends a user plane MBS Session Establishment Request (i.e., F1 MBS Session Establishment Request) to the selected gNB-DU21 and gNB-DU22, where the user plane MBS Session Establishment Request includes the IP multicast transmission address IP3 allocated by F-UP12, and the gNB-DU21 and gNB-DU22 respectively feed back a user plane MBS Session Establishment response to the gNB-CU (to save the layout, the gNB-DU21 and the gNB-DU22 are drawn together in fig. 18). The specific process is similar to the interaction process between S-CP and S-UP in step S1505a, and is not described again.

In step S1806a, if the gNB-DU11 and gNB-DU12 support receiving the data transmitted in the multicast mode, they respectively join the multicast transmission group corresponding to the IP multicast transmission address (i.e., IP 2) allocated by F-UP11 to receive the MBS service data sent by F-UP 11.

In step S1806b, if the gNB-DU21 and gNB-DU22 support receiving the data transmitted in the multicast mode, they respectively join the multicast transmission group corresponding to the IP multicast transmission address (i.e. IP 3) allocated by F-UP12 to receive the MBS service data sent by F-UP 12.

It should be noted that: similar to the previous embodiment, if the gNB-DU does not support receiving data transmitted based on multicast mode but supports receiving MBS service data in a point-to-point mode according to network configuration, a corresponding F-TEID needs to be allocated, and the F-TEID is allocated by the gNB-CU or by the gNB-DU.

In step S1807a, the gNB allocates wireless air interface resources according to the QFIs and QoS Profile included in the information transfer message received in step S1804 a.

In step S1807b, the gNB-CU sends an MBS session start response to the AMF. If there is a gNB-DU that does not support receiving Multicast-based data, the MBS session start response includes the F-TEID allocated by the gNB-DU (denoted as F-TEIDgnb-DU for the sake of distinction) and corresponds to F-UP, thereby forming a List of { F-UP ID, list of F-TEIDgnb-DU, multicast Enable }. In this embodiment, list of { F-UP ID, list of F-TEIDgnb-du, multicast Enable } includes List of F-TEIDgnb-du and Multicast Enable for F-UP11, and List of F-TEIDgnb-du and Multicast Enable for F-UP 12.

Similar to step S1507, since some of the gNB-DUs support receiving data transmitted in a multicast-based manner, while other gNB-DUs do not support receiving data transmitted in a multicast-based manner, this List F-TEIDgnb-DU corresponds only to those gNB-DUs that do not support receiving multicast transmission, but support receiving MBS traffic data using a point-to-point manner. Therefore, when all the gNB-DUs of an F-UP support the reception of the data transmitted based on the multicast mode, the List of F-TEIDgnb-DU corresponding to the F-UP is not included, and other descriptions refer to the related contents of step S1507.

Furthermore, when the gNB-CU decides not to assign any sub-user plane node to a certain F-UP ID/IDs, then the Multicast Enable corresponding to this/these F-UP ID/IDs can be set to Disable. Of course, a Failed List { F-UP } may also be employed in the MBS session start response to indicate the parent user plane node to which no gNB-DU is allocated.

In step S1807c, the AMF sends an information notification message Namf _ Communication _ nonen 2InfoNotify to the F-CP1 according to the MBS session start response received in step S1807 b. Wherein the information notification message comprises N2 MBS Session contact (N2 MBS Session Start Response (List of (F-UP ID, list of F-TEIDgnb-du, multi cast Enable))).

In step S1808a, F-CP1 sends a user plane MBS session modification request to F-UP11 according to the List of { F-UP ID, list of F-TEIDgnb-du, multicast Enable } contained in the received information notification message, and F-UP11 feeds back a user plane MBS session modification response to F-CP 1. The detailed description of this step is similar to that of step S1508, and is not repeated here.

In step S1808b, F-CP1 sends a user plane MBS session modification request to F-UP12 according to the List of { F-UP ID, list of F-TEIDgnb-du, multicast Enable } contained in the received information notification message, and F-UP12 feeds back a user plane MBS session modification response to F-CP 1. The detailed description of this step is similar to that of step S1508, and is not repeated here.

In step S1809, after performing steps S1804a to S1808b for each of the gnbs identified by the RAN ID, the F-CP1 sends an MBS session start response to the parent control plane node of the F-CP1 according to the MBS session start responses fed back by all the gnbs-CUs.

Similar to step S1609, the MBS session start response returned by F-CP1 to the F-CP1 parent control plane node contains the UP ID of the user plane node at the same level as the F-CP1 parent control plane node, and possibly also contains List of F-TEIDfup and Multicast Enable.

Steps S1801 to S1809 are processing procedures after the F-CP1 receives the MBS session start request sent by the parent control plane node of the F-CP1, in which the F-CP1 selects two user plane nodes F-UP11 and F-UP12 having the same level as that of the F-CP1, and the gNB-CU corresponding to the F-CP1 selects two child user plane nodes gNB-DU11 and gNB-DU12 having the same level as that of the gNB-CU for the F-UP11, and selects two child user plane nodes gNB-DU21 and gNB-DU22 having the same level as that of the gNB-CU for the F-UP 12.

With continued reference to FIG. 18, the method further includes the steps of:

in step S1810, the F-CP2 receives an MBS session start request sent by a parent control plane node of the F-CP 2. The specific process is similar to step S1501 and will not be described again. Wherein, the IP Multicast transmission address contained in the MBS IP Multicast Distribution in the MBS session start request is recorded as IPx.

In step S1811, after receiving the MBS session start request sent by the parent control plane node of the F-CP2, the F-CP2 may determine to select one or more user plane nodes from the multiple F-UPFs as peers of the F-CP2 according to the information (such as location, number, etc.) of the gNB corresponding to the F-CP 2. In this embodiment, it is assumed that only one user plane node F-UP21 is selected, then the F-CP2 sends a user plane MBS session establishment request to the F-UP21, and the F-UP21 feeds back a user plane MBS session establishment response to the F-CP 2.

For a detailed description, referring to the related contents of the foregoing step S1502, similar to step S1502, the F-UP21 allocates a new IP multicast transport address (denoted as IP4 for the sake of distinction) through the interaction between the user plane MBS session establishment request and the user plane MBS session establishment response between the F-CP2 and the F-UP 21.

In addition, similarly, if F-UP21 does not support receiving data transmitted based on multicast mode, F-UP21 allocates a F-TEID for receiving MBS service data in point-to-point mode, and carries the allocated F-TEID in the user plane MBS session establishment response.

Step S1812, if the F-UP21 supports receiving the data transmitted based on the multicast mode, apply for joining in the multicast transmission group corresponding to the IP multicast transmission address IPx to receive the MBS service data sent by the parent user plane node of the F-UP 21.

Step S1813a, the F-CP2 sends an information transfer message (i.e., namf _ Communication _ nonen 2 MessageTransfer) to the AMF. The detailed description of the information transmission message is similar to the aforementioned step S1804a, and is not repeated. However, it should be noted that: since the F-CP2 selects a user plane node F-UP21 having the same level as the F-CP2, the information transmission message contains the F-UP21 ID and MBS IP Multicast Distribution corresponding to the F-UP21 ID, and the IP Multicast transmission address contained in the MBS IP Multicast Distribution is IP4. When a plurality of RAN IDs are recorded in the MBS Session Context in the F-CP2, the subsequent steps S1813b to S1817 are performed for the gnbs identified by each RAN ID, respectively.

It should be noted that: step S1813a and step S1804a have no precedence relationship, and they may be steps executed by F-CP2 and F-CP1 respectively in parallel.

In step S1813b, the AMF sends an MBS session start request to the corresponding gNB-CU according to the RAN ID contained in the information transfer message in step S1813a, including the parameters in step S1813 a.

After receiving the MBS session start request sent by the AMF, the gNB-CU selects one or more gNB-DUs for the F-UP21 from the multiple gNB-DUs respectively according to the number and the position (for MBS multimedia Service) of the registered MBS multimedia Service UE or MBS Broadcast Service Area (for MBS Broadcast Service). In this embodiment, it is assumed that gNB-DU31 and gNB-DU32 are selected for F-UP21, i.e., the gNB-DU selected for F-UP21 is different from the gNB-DU selected for F-UP11 and F-UP 12.

Step S1814, the gNB-CU sends a user plane MBS Session Establishment Request (i.e. F1 MBS Session Establishment Request) to the selected gNB-DU31 and gNB-DU32 respectively, where the user plane MBS Session Establishment Request includes the IP multicast transmission address IP4 allocated by F-UP21, and the gNB-DU31 and gNB-DU32 respectively feed back a user plane MBS Session Establishment response to the gNB-CU (to save the layout, the gNB-DU31 and the gNB-DU32 are drawn together in fig. 18). The specific process is similar to step S1505a and will not be described again.

In step S1815, if the gNB-DU31 and the gNB-DU32 support receiving the data transmitted in the multicast mode, they respectively join the multicast transmission group corresponding to the IP multicast transmission address (i.e. IP 4) allocated by the F-UP21 to receive the MBS service data sent by the F-UP 21.

It should be noted that: similar to the previous embodiment, if the gNB-DU does not support receiving data transmitted based on multicast mode but supports receiving MBS service data in a point-to-point mode according to network configuration, a corresponding F-TEID needs to be allocated, and the F-TEID is allocated by the gNB-CU or by the gNB-DU.

In step S1816a, the gNB allocates wireless air interface resources according to the QFIs and the QoS Profile included in the information transfer message received in step S1813 a.

In step S1816b, the gNB-CU sends an MBS session start response to the AMF. If there is a gNB-DU that does not support receiving data transmitted in a multicast-based manner, the MBS session start response includes the F-TEIDgnb-DU allocated by the gNB-DU, and corresponds to F-UP21. Other descriptions may refer to the relevant contents of step S1507.

In step S1816c, the AMF sends an information notification message Namf _ Communication _ nonen 2InfoNotify to the F-CP2 according to the MBS session start response received in step S1816 b. Wherein, the information notification message contains (N2 MBS Session contact (N2 MBS Session Start Response (F-UP 21 ID, list of F-TEIDgnb-du, multi cast Enable))).

Step S1817, F-CP2 sends the user plane MBS session modification request to F-UP21 according to the F-UP21 ID and List of F-TEIDgnb-du contained in the received information notification message, and F-UP21 feeds back the user plane MBS session modification response to F-CP 2. The detailed description of this step is similar to that of step S1508, and is not repeated here.

In step S1818, after performing steps S1813b to S1817 for the gNB identified by each RAN ID, the F-CP2 sends an MBS session start response to the parent control plane node of the F-CP2 according to the MBS session start responses fed back by all the gNB-CUs.

Similar to step S1509, the MBS session start response that the F-CP2 replies to the F-CP2 'S parent control plane node contains the UPx ID of the peer user plane nodes with the F-CP 2' S parent control plane node, and possibly a List of F-TEIDfup.

Wherein, steps S1810 to S1818 are the processing procedure after the F-CP2 receives the MBS session start request sent by the parent control plane node of the F-CP2, in which the F-CP2 selects one user plane node F-UP21 at the same level as the F-CP2, and the gNB-CU corresponding to the F-CP2 selects two child user plane nodes gNB-DU31 and gNB-DU32 at the same level as the gNB-CU.

As can be seen from steps S1801 to S1818, in the embodiment of the present application, the gNB-CU may have multiple parent control plane nodes F-CP1 and F-CP2, and the gNB-DU controlled by the gNB-CU has only one parent user plane node.

In addition, the message in step S1801 and the message in step S1810 may be issued in parallel, and thus steps S1801 to S1809 and steps S1810 to S1818 may be executed in parallel. Thus, in the process of establishing the user plane MBS session, there may exist a user plane node simultaneously sent the user plane MBS session establishment request message by two control plane nodes, or a user plane MBS session establishment request message sent by another control plane node is received after being selected by a control plane node. If a user plane node receives a user plane MBS session establishment request message sent by two control plane nodes (certainly, there may be more, and two are exemplified here) at the same time, the user plane node may normally respond to the user plane MBS session establishment request sent by one of the control plane nodes in a user plane MBS session establishment response message, and Reject (Reject) another control plane node in another user plane MBS session establishment response message to indicate that the user plane node has been selected. If a user plane node has a father user plane node through a control plane node and receives a user plane MBS conversation establishing request message sent by another control plane node, the other control plane node is objected in another user plane MBS conversation establishing response message to indicate that the user plane node has been selected.

After the establishment of the MBS session transmission tree is completed, the following steps may be performed:

in step S1819a, the F-UP11 receives the downlink MBS service data sent by the parent user plane node of the F-UP 11. The received downlink MBS service data is then transmitted to the gNB-DU11 and gNB-DU12 through step S1820 a. Each user plane node transmits MBS service data in the multicast transmission mode or the point-to-point transmission mode determined in the previous step, and simultaneously each user plane node receives the MBS service data in the multicast transmission mode or the point-to-point transmission mode determined in the previous step.

In step S1819b, the F-UP12 receives the downlink MBS service data sent by the parent user plane node of the F-UP 12. The received downlink MBS service data is then transmitted to the gNB-DU21 and the gNB-DU22 through step S1820 b. Each user plane node transmits MBS service data in the multicast transmission mode or the point-to-point transmission mode determined in the previous step, and simultaneously each user plane node receives the MBS service data in the multicast transmission mode or the point-to-point transmission mode determined in the previous step.

In step S1819c, the F-UP21 receives the downlink MBS service data sent by the parent user plane node of the F-UP 21. The received downlink MBS service data is then transmitted to the gNB-DU31 and the gNB-DU32 through step S1820 c. Each user plane node transmits MBS service data in the multicast transmission mode or the point-to-point transmission mode determined in the previous step, and simultaneously each user plane node receives MBS service data in the multicast transmission mode or the point-to-point transmission mode determined in the previous step.

The technical solution of the embodiment shown in fig. 18 is mainly a process of establishing a control plane transmission tree and a user plane transmission tree after introducing an NR base station into an MBS session transmission tree. It should be noted that, in the embodiments shown in fig. 15, fig. 16, and fig. 18, only the interaction process between two levels of nodes in the MBS session transmission tree is described, and for an MBS session transmission tree including three or more levels of nodes, the interaction process between any two levels of nodes may be implemented with reference to the embodiments shown in fig. 15, fig. 16, or fig. 18. For example, as shown in fig. 19, the two-level nodes shown in 1901 and 1902 may be two-level nodes shown in fig. 15 or fig. 16, and after superimposing the child control plane node S-CP and the child user plane node S-UP in 1901 and the parent control plane F-CP node and the parent user plane node F-UP in 1902 into the same entity, respectively, a three-level MBS session transmission tree may be implemented as shown in 1903 in fig. 19, where GF-CP is the parent control plane node of F-CP and GF-UP is the parent user plane node of F-UP. Based on the mode, the MBS conversation transmission tree of any level can be realized.

For the embodiment shown in fig. 18, since the base station can only be the last stage of the network side, the embodiment shown in fig. 18 and the embodiments shown in fig. 15 and fig. 16 can be combined to realize the MBS session transmission tree including any stage of the base station.

Fig. 15, fig. 16 and fig. 18 show the establishment process of the MBS session transmission tree according to the embodiment of the present application, and the user plane transmission tree may also be broken during the establishment process of the MBS session, so that an operation of deleting the broken branches is also required.

As shown in fig. 20, the method may include the following steps:

in step S2001, the F-CP1 receives the MBS session start request sent by the parent control plane node of the F-CP 1. The specific process is similar to step S1501 and will not be described again. Wherein, the IP Multicast transmission address contained in the MBS IP Multicast Distribution in the MBS session start request is recorded as IP1.

After receiving the MBS session start request sent by the parent control plane node of the F-CP1, the F-CP1 may determine to select one or more F-UPFs from the multiple F-UPFs as the user plane nodes at the same level as the F-CP1 according to the information of the child control plane nodes of the F-CP1, where it is assumed in this embodiment that two user plane nodes F-UP11 and F-UP12 are selected. Then, step S1602a and step S1602b are respectively performed.

In step S2002a, the F-CP1 sends a user plane MBS conversation establishment request to the F-UP11, and the F-UP11 feeds back a user plane MBS conversation establishment response to the F-CP 1. The process is similar to the process of step S1502 in the foregoing embodiment, and is not described again, where the IP multicast transport address allocated by F-UP11 in step S2002a is denoted as IP2.

Step S2002b, F-CP1 sends user plane MBS conversation establishment request to F-UP12, F-UP12 feeds back user plane MBS conversation establishment response to F-CP 1. The process is similar to the process of step S1502 in the foregoing embodiment, and is not described again, where the IP multicast transport address allocated by the F-UP12 in step S2002b is denoted as IP3.

Step S2003, if the F-UP11 and the F-UP12 support receiving the data transmitted based on the multicast mode, applying for joining in the multicast transmission group corresponding to the IP multicast transmission address IP1 to receive MBS service data sent by the father user plane node of the F-UP11 and the F-UP 12.

In step S2004, the F-CP1 sends the MBS session start request to each sub-control plane sub-node according to the information of the sub-control plane node of the F-CP1, that is, steps S2004 to S2008 are executed for each sub-control plane node separately, and this embodiment is described by taking sending to one sub-control plane node S-CP as an example.

The MBS session start request sent by the F-CP1 to the S-CP of the sub-control plane node of the F-CP1 comprises the following parameters: TMGI, MBS Session Duration, MBS QFIs, qoS Profile, MBS Time to Data Transfer, list of { F-UP ID, MBS transmission information }, MBS Service Area. The MBS transmission information is MBS IP Multicast Distribution (C-TEID). In this embodiment, since F-CP1 selects two user plane nodes F-UP11 and F-UP12 with the same level as F-CP1, the List of { F-UP ID, MBS transmission information } includes MBS IP Multicast Distribution corresponding to F-UP11 ID and F-UP11 ID, and MBS IP Multicast Distribution corresponding to F-UP12 ID and F-UP12 ID. MBS IP Multicast Distribution corresponding to the F-UP11 ID is distributed by the F-UP11, wherein the contained IP Multicast transmission address is IP2; the MBS IP Multicast Distribution corresponding to the F-UP12 ID is allocated by the F-UP12, and the IP Multicast transmission address contained in the MBS is IP3.

It should be noted that: the IP multicast transport address IP3 assigned by F-UP12 and the IP multicast transport address IP2 assigned by F-UP11 cannot be the same, but the assigned C-TEID may be the same.

After receiving the MBS session start request sent by F-CP1, the S-CP selects one or more S-UPs for F-UP11 and one or more S-UPs for F-UP12 from the plurality of S-UPs according to the information of the sub-control plane nodes of the S-CP, similarly to step S1502, in this embodiment, it is assumed that S-UP11 and S-UP12 are selected for F-UP11, but no sub-user plane node is selected for F-UP 12. Step S2005 is then executed.

In step S2005, the S-CP sends a user plane MBS session establishment request to the selected S-UP11 and S-UP12, where the user plane MBS session establishment request includes the IP multicast transport address IP2 allocated by F-UP11, and the S-UP11 and S-UP12 feed back a user plane MBS session establishment response to the S-CP respectively (to save the layout, S-UP11 and S-UP12 are drawn together in fig. 20). The specific process is similar to step S1505a and will not be described again.

In step S2006, if S-UP11 and S-UP12 support receiving data transmitted in a multicast manner, they respectively join the multicast transmission group corresponding to the IP multicast transmission address (i.e. IP 2) allocated by F-UP11 to receive MBS service data transmitted by F-UP 11.

In step S2007, the S-CP sends an MBS session start response to the F-CP 1. If there is S-UP that does not support receiving data transmitted by Multicast, the MBS session start response includes the S-UP allocated F-TEID and corresponds to F-UP, thereby forming a List of { F-UP ID, list of F-TEID, multicast Enable }. In this embodiment, list of { F-UP ID, list of F-TEIDsup, multicast Enable } includes List of F-TEIDsup and Multicast Enable for F-UP11, and Multicast Enable (valued Disable) for F-UP 12. Since F-UP12 does not assign F-TEID while the corresponding Multicast Enable is set to Disable, this indicates that no sub-user plane node has been selected for F-UP 12.

Similar to step S1507, since some S-UPs support receiving data transmitted based on multicast and some other S-UPs do not support receiving data transmitted based on multicast, this List F-TEIDsup corresponds only to those S-UPs that do not support receiving multicast transmission but support receiving MBS service data using point-to-point. Therefore, when all S-UPs of an F-UP support receiving data transmitted based on multicast, the List of F-TEIDsup corresponding to the F-UP is not available, and other descriptions refer to the related contents of step S1507.

Furthermore, when the S-CP decides not to allocate any sub-user plane node to some F-UP ID/IDs, besides setting the Multicast Enable parameter corresponding to this/these F-UP IDs to Disable, failed List { F-UP } can be used in the MBS session start response to indicate the parent user plane node to which no sub-user plane node is allocated.

In step S2008a, F-CP1 sends a user plane MBS session modification request to F-UP11 according to List of { F-UP ID, list of F-TEIDsup, multicast Enable } contained in the MBS session start response, and F-UP11 feeds back the user plane MBS session modification response to F-CP 1. The detailed description of this step is similar to that of step S1508, and is not repeated here.

It should be noted that: if F-CP1 determines that all the sub-control plane nodes of F-CP1 do not allocate sub-user plane nodes to F-UP11, F-CP1 sends a user plane MBS session deletion request to F-UP11, F-UP11 sends an IGMP Leave data packet after receiving the user plane MBS session deletion request, and deletes the user plane MBS session deletion request from the multicast transmission group indicated by the multicast transmission address IP1 allocated by the parent user plane node of F-UP11, and F-UP11 replies a user plane MBS session deletion response to F-CP1 (the process is not identified in the figure).

In step S2008b, after receiving the MBS session start response replied by all the child control plane nodes of F-CP1, F-CP1 determines that all the child control plane nodes of F-CP1 do not assign a child user plane node to F-UP12, then sends a user plane MBS session deletion Request (i.e., N4 MBS sessiondelete Request) to F-UP12, F-UP12 sends an IGMP Leave packet after receiving the user plane MBS session deletion Request, indicating deletion from the multicast transmission group indicated by the multicast transmission address (i.e., IP 1) assigned by the parent user plane node of F-UP12, and F-UP12 replies a user plane MBS session deletion response to F-CP 1.

It should be noted that: steps S2004 to S2008 are performed separately for each sub-control plane node of F-CP1, and the operation of performing the MBS session deletion of step S2008b cannot be started only because the MBS session start response replied by one sub-control plane node of F-CP1 in step S2007 indicates that no sub-user plane node is allocated to F-UP 12. The F-CP1 determines, after receiving the replies from all the sub-control plane nodes, which user plane node is not allocated with the sub-user plane node, to determine whether to delete the MBS session with the user plane node.

In step S2009, after performing steps S2004 to S2008 for each child control plane, the F-CP1 sends an MBS session start response to the parent control plane node of the F-CP1 according to the MBS session start response fed back by all the child control planes.

Similar to step S1509, the MBS session start response returned by F-CP1 to the F-CP1 parent control plane node contains the user plane node UP ID of the peer with the F-CP1 parent control plane node, and may also contain List of F-TEID (for the sake of distinction, it is denoted as List of F-TEIDfup), since F-CP1 selects two user plane nodes F-UP11 and F-UP12 of the peer with F-CP1, but S-CP does not assign a sub-user plane node to F-UP12, so if the MBS session start response returned by F-CP1 to the F-CP1 parent control plane node contains List of F-TEIDfup, it also contains only F-TEID assigned by F-UP 11.

It should be noted that, if the MBS session start response returned by the F-CP1 to the parent control plane node of the F-CP1 may not include the F-TEID allocated by the F-UP11, in this case, it is indicated that the F-UP11 supports receiving the data transmitted in the Multicast manner, and at this time, the MBS session start response returned by the F-CP1 to the parent control plane node of the F-CP1 does not need to include Multicast Enable; if the MBS session start response replied by the F-CP1 to the parent control plane node of the F-CP1 contains the F-TEID distributed by the F-UP11, the result shows that the F-UP11 does not support the reception of the data transmitted based on the Multicast mode but supports the MBS service data transmitted by the point-to-point mode, in this case, the MBS session start response replied by the F-CP1 to the parent control plane node of the F-CP1 does not need to contain Multicast Enable because only one user plane node F-UP11 has the same level with the F-CP 1.

After the MBS session transmission tree establishment is completed, the following steps may be performed:

in step S2010, the F-UP11 receives the downlink MBS service data sent by the parent user plane node of the F-UP 11. The received downlink MBS service data is then transmitted to the S-UP11 and S-UP12 through step S2011. Each user plane node transmits MBS service data in the multicast transmission mode or the point-to-point transmission mode determined in the previous step, and simultaneously each user plane node receives MBS service data in the multicast transmission mode or the point-to-point transmission mode determined in the previous step.

In the embodiment shown in fig. 20, although F-CP1 selects two user plane nodes F-UP11 and F-UP12 having the same level as F-CP1, the sub-control plane node S-CP of F-CP1 does not allocate a sub-user plane node to F-UP12, that is, a broken branch occurs in the user plane transmission tree, and thus the existing broken branch needs to be deleted.

In an embodiment of the present application, the MBS Session may also be participated by a UPF other than a PDU (Protocol Data Unit) Session Anchor, in which case, the process of establishing the user plane MBS transmission tree may be as shown in fig. 21, and includes the following steps:

In step S2101, the F-CP1 receives an MBS session start request sent by the parent control plane node of the F-CP 1. The specific process is similar to step S1501 and will not be described again. Wherein, the IP Multicast transmission address contained in the MBS IP Multicast Distribution in the MBS session start request is recorded as IP1.

After receiving the MBS session start request sent by the parent control plane node of the F-CP1, the F-CP1 may determine to select one or more F-UPFs from the multiple F-UPFs as user plane nodes of the same level as the F-CP1 according to the information of the child control plane nodes of the F-CP1, where in this embodiment, it is assumed that two user plane nodes are selected and denoted as F-UP11 and F-UP12. Then, step S2102a and step S2102b are executed, respectively.

In step S2102a, F-CP1 sends a user plane MBS session establishment request to F-UP11, and F-UP11 feeds back a user plane MBS session establishment response to F-CP 1. The process is similar to the process of step S1502 in the foregoing embodiment, and is not described again, wherein the IP multicast transport address allocated by F-UP11 in step S2102a is denoted as IP2.

Step S2102b, F-CP1 sends user plane MBS conversation establishment request to F-UP12, F-UP12 feeds back user plane MBS conversation establishment response to F-CP 1. The process is similar to the process of step S1502 in the foregoing embodiment, and is not described again, wherein the IP multicast transport address allocated by F-UP12 in step S2102b is denoted as IP3.

Step S2103, if F-UP11 and F-UP12 support receiving data transmitted based on multicast mode, apply for joining in the multicast transmission group corresponding to IP multicast transmission address IP1 to receive MBS service data sent by the father user plane node of F-UP11 and F-UP 12.

After executing step S2102a and step S2102b, the F-CP1 may select to execute step S2104a, step S2104b, and step S2104c, and select the user plane nodes F-UP21, F-UP22, and F-UP23 (the selection of the user plane nodes and the number of the user plane nodes by the F-CP1 are only examples), which aims to enable the F-UP11 and the F-UP12 to perform offloading or optimized transmission through the F-UP21, the F-UP22, and the F-UP 23.

For example, when the distance between the F-UP11 and the next level user plane node of the F-UP11 is long and the number of the next level user plane nodes of the F-UP11 is very large, if MBS service data is directly transmitted to the next level user plane node of the F-UP11 by the F-UP11, such transmission efficiency is very low. And by introducing the F-UP21, the F-UP22 and the like between the F-UP11 and the next-level user plane node of the F-UP11, the MBS service data can be sent to the next-level user plane node through the F-UF21 by the F-UP11, so that the data transmission efficiency can be effectively improved.

Steps S2104a, S2104b, and S2104c are described below:

step S2104a, F-CP1 sends user plane MBS conversation establishment request to F-UP21, F-UP21 feeds back user plane MBS conversation establishment response to F-CP 1. The process is similar to the process of step S1502 in the previous embodiment, and is not described again. In step S2104a, F-UP21 also allocates a new IP multicast transmission address, identified in this embodiment as IP4, for transmitting MBS service data to the sub-user plane nodes of F-UP 21. And, if the F-UP21 does not support receiving MBS service data transmitted by the F-UP11 in a multicast manner, the F-UP21 allocates an F-TEID to receive MBS service data from the F-UP11 in a point-to-point manner.

Step S2104b, F-CP1 sends user plane MBS conversation establishment request to F-UP22, F-UP22 feeds back user plane MBS conversation establishment response to F-CP 1. The process is similar to the process of step S1502 in the previous embodiment, and is not described again. In step S2104b, F-UP22 also assigns a new IP multicast transmission address, identified in this embodiment as IP5, for transmitting MBS service data to the sub-user plane nodes of F-UP 22. And, if F-UP22 does not support receiving MBS service data transmitted by F-UP11 in a multicast manner, F-UP22 may allocate an F-TEID to receive MBS service data from F-UP11 in a point-to-point manner.

It should be noted that, in an embodiment of the present application, the Multicast transmission address in the MBS IP Multicast Distribution included in the user plane MBS session establishment request in step S2104a and step S2104b is the Multicast transmission address IP2 in step S2102 a.

Step S2104c, F-CP1 sends user plane MBS session establishment request to F-UP23, F-UP23 feeds back user plane MBS session establishment response to F-CP 1. Meanwhile, F-UP23 also allocates a new IP multicast transmission address, identified as IP6 in this embodiment, for transmitting MBS service data to the sub-user plane nodes of F-UP 23. The process is similar to the process of step S1502 in the previous embodiment, and is not described again.

In an embodiment of the present application, the Multicast transmission address in the MBS IP Multicast Distribution included in the user plane MBS session establishment request in step S2104c is the Multicast transmission address IP3 in step S2102 b. Wherein the new multicast transmission address determined in step S2104c is assigned by F-UP23 to the sub-user plane node of F-UP23 (i.e., S-UP31 and S-UP32 in fig. 21). And, if the F-UP23 does not support receiving MBS service data transmitted by the F-UP12 in a multicast manner, the F-UP23 allocates an F-TEID to receive MBS service data from the F-UP12 in a point-to-point manner.

In step S2105a, if F-UP21 and F-UP22 support receiving data transmitted based on a multicast mode, apply for joining in a multicast transmission group corresponding to an IP multicast transmission address IP2 to receive MBS service data sent by F-UP 11.

Step S2105b, if the F-UP23 supports receiving the data transmitted based on the multicast mode, applies for joining the multicast transmission group corresponding to the IP multicast transmission address IP3 to receive the MBS service data sent by the F-UP 12.

In step S2106a, if there is a user plane node that does not support receiving multicast transmission but supports receiving MBS service data in a point-to-point manner in F-UP21 and F-UP22, F-CP1 sends a user plane MBS session modification request to F-UP11, and F-UP11 feeds back a user plane MBS session modification response to F-CP 1. Wherein, the user plane MBS conversation modifying request comprises F-TEID distributed by the user plane node which does not support receiving multicast transmission and supports receiving MBS service data by using a point-to-point mode in the F-UP21 and the F-UP22, so as to indicate the F-UP11 to increase to use the point-to-point mode to transmit the MBS service data to the user plane node which does not support receiving multicast transmission and supports receiving MBS service data by using the point-to-point mode in the F-UP21 and the F-UP 22.

In step S2106b, if the F-UP23 does not support receiving the data transmitted based on the multicast mode but supports receiving the MBS service data using the point-to-point mode, the F-CP1 sends a user plane MBS session modification request to the F-UP12, and the F-UP12 feeds back a user plane MBS session modification response to the F-CP 1. Wherein, the user plane MBS conversation modifying request comprises F-TEID allocated by F-UP23, so as to instruct F-UP12 to transmit MBS service data to F-UP23 in a point-to-point mode.

In step S2107, the F-CP1 sends an MBS session start request to the sub control surface node S-CP1 of the F-CP1 according to the information of the sub control surface node of the F-CP 1.

The MBS session start request sent by the F-CP1 to the sub-control plane node S-CP1 of the F-CP1 comprises the following parameters: TMGI, MBS Session Duration, MBS QFISs, qoS Profile, MBS Time to Data Transfer, list of { F-UP ID, MBS transmission information }, MBS Service Area. The MBS transmission information is MBS IP Multicast address (C-TEID). In this embodiment, the List of { F-UP ID, MBS transmission information } includes the MBS IP Multicast Distribution corresponding to the F-UP21 ID and the F-UP21 ID, and the MBS IP Multicast Distribution corresponding to the F-UP22 ID and the F-UP22 ID. The MBS IP Multicast Distribution corresponding to the F-UP21 ID is allocated by the F-UP21, wherein the included IP Multicast transmission address is the new IP Multicast transmission address IP4 allocated by the F-UP21 in step S2104 a; the MBS IP Multicast Distribution corresponding to the F-UP22 ID is allocated by the F-UP22, the IP Multicast transmission address included therein is the new IP Multicast transmission address IP5 allocated by the F-UP22 in step S2104b, and the new IP Multicast transmission address IP4 allocated by the F-UP21 in step S2104a is different from the new IP Multicast transmission address IP5 allocated by the F-UP22 in step S2104 b.

In step S2108, after receiving the MBS session start request sent by the F-CP1, the S-CP1 performs the user plane MBS session establishment process. Specifically, S-CP1 selects one or more S-UPs for F-UP21 and one or more S-UPs for F-UP22 from among a plurality of S-UPs according to information of sub-control plane nodes of S-CP1, and in this embodiment, it is assumed that S-UP11 and S-UP12 are selected for F-UP21 and S-UP22 are selected for F-UP22, i.e., different sub-user plane nodes are selected for F-UP21 and F-UP 22. Then S-CP1 sends user plane MBS conversation establishment request to the sub user plane nodes (namely S-UP11, S-UP12, S-UP21 and S-UP 22) selected for F-UP21 and F-UP22 respectively, and receives user plane MBS conversation establishment response fed back by the sub user plane nodes. Meanwhile, if the sub-user plane nodes support receiving multicast transmission, the sub-user plane nodes can join corresponding multicast transmission groups to receive MBS service data (namely, S-UP11 and S-UP12 join the multicast transmission group corresponding to IP4, and S-UP21 and S-UP22 join the multicast transmission group corresponding to IP 5); if some of the sub-user plane nodes do not support receiving the data transmitted in the multicast manner but support receiving the MBS service data in the point-to-point manner, the sub-user plane nodes that do not support receiving the data transmitted in the multicast manner but support receiving the MBS service data in the point-to-point manner may allocate the F-TEID to receive the MBS service data in the point-to-point manner, which is similar to the step S1505a and the step S1506, and will not be described again.

In step S2109, the S-CP1 sends an MBS session start response to the F-CP 1. If there is an S-UP that does not support receiving data transmitted based on Multicast mode but supports receiving MBS service data using point-to-point mode, the MBS session start response includes the F-TEID allocated by the S-UP and corresponds to the F-UP, thereby forming a List of { F-UP ID, list of F-TEIDsup, multicast Enable }. In this embodiment, list of { F-UP ID, list of F-TEIDsup, multicast Enable } contains List of F-TEIDsup and Multicast Enable for F-UP21, and List of F-TEIDsup and Multicast Enable for F-UP 22.

Similar to step S1507, since some S-UPs support receiving data transmitted based on multicast and some other S-UPs do not support receiving data transmitted based on multicast, this List F-TEIDsup corresponds only to those S-UPs that do not support receiving multicast transmission but support receiving MBS service data using point-to-point. Therefore, when all S-UPs of an F-UP support receiving data transmitted based on multicast, the List of F-TEIDsup corresponding to the F-UP is not available, and other descriptions refer to the related contents of step S1507.

In addition, when S-CP1 decides not to assign any sub-user plane node to some F-UP ID/IDs, then Multicast Enable corresponding to this/these F-UP ID/IDs can be set to Disable. Of course, failed List { F-UP } may also be employed in the MBS session start response to indicate the F-UP to which no child user plane node is allocated.

In step S2110a, F-CP1 sends a user plane MBS session modification request to F-UP21 according to List of { F-UP ID, list of F-TEIDsup, multicast Enable } contained in the MBS session start response fed back by S-CP1, and F-UP21 feeds back a user plane MBS session modification response to F-CP 1. The detailed description of this step is similar to that of step S1508, and is not repeated here.

In step S2110b, F-CP1 sends a user plane MBS session modification request to F-UP22 according to the List of { F-UP ID, list of F-TEIDsup, multicast Enable } contained in the MBS session start response fed back by S-CP1, and F-UP22 feeds back the user plane MBS session modification response to F-CP 1. The detailed description of this step is similar to that of step S1508, and is not repeated here.

And step S2111, the F-CP1 sends an MBS conversation starting request to the sub control surface node S-CP2 of the F-CP1 according to the information of the sub control surface node of the F-CP 1.

The MBS session start request sent by the F-CP1 to the sub-control plane node S-CP2 of the F-CP1 comprises the following parameters: TMGI, MBS Session Duration, MBS QFISs, qoS Profile, MBS Time to Data Transfer, list of { F-UP ID, MBS transmission information }, MBS Service Area. The MBS transmission information is MBS IP Multicast Distribution (C-TEID). In this embodiment, the List of { F-UP ID, MBS transmission information } includes the F-UP23 ID and the MBS IP Multicast Distribution corresponding to the F-UP23 ID. The MBS IP Multicast Distribution corresponding to the F-UP23 ID is allocated by the F-UP23, wherein the included IP Multicast transport address is the new IP Multicast transport address IP6 allocated by the F-UP23 in step S2104 c.

It should be noted that: there is no precedence relationship between step S2111 and step S2107, and they may be steps executed by the F-CP1 in parallel respectively.

Step S2112, after S-CP2 receives MBS conversation start request sent by F-CP1, the user plane MBS conversation establishment process is carried out. Specifically, the S-CP2 selects one or more S-UPs for the F-UP23 from the plurality of S-UPs according to the information of the sub-control plane node of the S-CP2, and in this embodiment, it is assumed that S-UP31 and S-UP32 are selected for the F-UP23, that is, the sub-user plane node selected for the F-UP23 is different from the sub-user plane node selected for the F-UP21 and the F-UP 22. Then S-CP2 sends request for establishing user plane MBS conversation to sub user plane nodes (namely S-UP31 and S-UP 32) selected for F-UP23, and receives response for establishing user plane MBS conversation fed back by S-UP31 and S-UP 32. Meanwhile, if S-UP31 and S-UP32 support receiving multicast transmission, a multicast transmission group corresponding to the new IP multicast transmission address IP6 allocated by F-UP23 in step S2104c may be added to receive MBS service data sent by F-UP 23; if some sub-user plane nodes in S-UP31 and S-UP32 do not support receiving data transmitted based on multicast mode but support receiving MBS service data using point-to-point mode, the sub-user plane nodes in S-UP31 and S-UP32 that do not support receiving data transmitted based on multicast mode but support receiving MBS service data using point-to-point mode may allocate F-TEID to receive MBS service data transmitted by F-UP23 using point-to-point mode, the specific procedure is similar to step S1505a and step S1506, and is not described again.

In step S2113, the S-CP2 sends an MBS session start response to the F-CP 1. If one of S-UP31 and S-UP32 does not support receiving Multicast-based data but supports receiving MBS service data using a point-to-point manner, the MBS session start response includes the S-UP-allocated F-TEID and corresponds to the F-UP, thereby forming a List of { F-UP ID, list of F-TEIDsup, multicast Enable }. In this embodiment, list of { F-UP ID, list of F-TEIDsup, multicast Enable } contains List of F-TEIDsup and Multicast Enable for F-UP 23.

Similar to step S1507, since some S-UPs support receiving data transmitted based on multicast and some other S-UPs do not support receiving data transmitted based on multicast, this List F-TEIDsup corresponds only to those S-UPs that do not support receiving multicast transmission but support receiving MBS service data using point-to-point. Therefore, when all S-UP of an F-UP supports receiving data transmitted based on multicast, list of F-TEIDsup corresponding to the F-UP is not available, and other descriptions refer to the related contents of step S1507.

In addition, when S-CP2 decides not to assign any sub-user plane node to one/some F-UP ID (S), then Multicast Enable corresponding to the/these F-UP ID (S) can be set to Disable. Of course, failed List { F-UP } may also be employed in the MBS session start response to indicate the F-UP to which no child user plane node is allocated.

In step S2114, F-CP1 sends a user plane MBS session modification request to F-UP23 according to the List of { F-UP ID, list of F-TEIDsup, multicast Enable } contained in the MBS session start response fed back by S-CP2, and F-UP23 feeds back a user plane MBS session modification response to F-CP 1. The detailed description of this step is similar to that of step S1508, and is not repeated here.

Step S2115, after the F-CP1 receives the MBS session start response fed back by all the S-CPs, the F-CP1 sends the MBS session start response to the father control surface node of the F-CP1 according to the MBS session start response fed back by all the S-CPs.

Similar to step S1609, the MBS session start response replied by F-CP1 to the F-CP1 parent control plane node contains the UP ID (which is the identity of the user plane node that is sibling to the F-CP1 parent control plane node), and possibly also the List of F-TEIDfup and Multicast Enable.

It can be seen from steps S2101 to S2115 that, in the embodiment of the present application, F-CP1 has two sub-control plane nodes S-CP1 and S-CP2, F-CP1 selects next-level user plane nodes F-UP21 and F-UP22 for F-UP11, F-CP1 selects next-level user plane node F-UP23 for F-UP12, S-CP1 selects sub-user plane nodes S-UP11 and S-UP12 for F-UP21, S-CP1 selects sub-user plane nodes S-UP21 and S-UP22 for F-UP22, and S-CP2 selects sub-user plane nodes S-UP31 and S-UP32 for F-UP 23.

It should be noted that: in the process of establishing the user plane MBS session, a user plane node may be simultaneously sent by two control plane nodes to establish the user plane MBS session request message, or the user plane MBS session establishment request message sent by another control plane node is received after being selected by one control plane node. If a user plane node receives a user plane MBS session establishment request message sent by two control plane nodes (certainly, there may be more, and two are exemplified here) at the same time, the user plane node may normally respond to the user plane MBS session establishment request sent by one of the control plane nodes in a user plane MBS session establishment response message, and Reject (Reject) another control plane node in another user plane MBS session establishment response message to indicate that the user plane node has been selected. If a user plane node has a father user plane node through a control plane node and receives a user plane MBS conversation establishing request message sent by another control plane node, the other control plane node is objected in another user plane MBS conversation establishing response message to indicate that the user plane node has been selected.

After the establishment of the MBS session transmission tree is completed, the following steps may be performed:

in step S2116a, the F-UP11 receives the downlink MBS service data sent by the father user plane node of the F-UP 11. And then transmits the received downlink MBS service data to the F-UP21 through step S2117a, and transmits the downlink MBS service data received through step S2117b to the F-UP22.F-UP21 transmits the received downlink MBS service data to S-UP11 and S-UP12 through step S2118 a. F-UP22 transmits the received downlink MBS service data to S-UP21 and S-UP22 through step S2118 b. Each user plane node transmits MBS service data in the multicast transmission mode or the point-to-point transmission mode determined in the previous step, and simultaneously each user plane node receives the MBS service data in the multicast transmission mode or the point-to-point transmission mode determined in the previous step.

In step S2116b, the F-UP12 receives the downlink MBS service data sent by the father user interface node of the F-UP 12. The received downlink MBS service data is then transmitted to the F-UP23 through step S2117c, and the F-UP23 transmits the received downlink MBS service data to the S-UP31 and the S-UP32 through step S2118 c. Each user plane node transmits MBS service data in the multicast transmission mode or the point-to-point transmission mode determined in the previous step, and simultaneously each user plane node receives the MBS service data in the multicast transmission mode or the point-to-point transmission mode determined in the previous step.

For the application scenario shown in fig. 21 where a non-PSA UPF participates in an MBS session, it is also necessary to prevent the occurrence of branch breaking, and a specific process may be shown in fig. 22, which includes the following steps:

in step S2201, the F-CP1 receives the MBS session start request sent by the parent control plane node of the F-CP 1. The specific process is similar to step S1501 and will not be described again. Wherein, the IP Multicast transmission address contained in the MBS IP Multicast Distribution in the MBS session start request is recorded as IP1.

After receiving the MBS session start request sent by the parent control plane node of the F-CP1, the F-CP1 may determine to select one or more F-UPFs from the multiple F-UPFs as user plane nodes of the same level as the F-CP1 according to the information of the child control plane nodes of the F-CP1, where in this embodiment, it is assumed that two user plane nodes are selected and denoted as F-UP11 and F-UP12. Then, step S2202a and step S2202b are executed, respectively.

In step S2202a, the F-CP1 sends a user plane MBS conversation establishment request to the F-UP11, and the F-UP11 feeds back a user plane MBS conversation establishment response to the F-CP 1. The process is similar to the process of step S1502 in the foregoing embodiment, and is not described again, where the IP multicast transport address allocated by the F-UP11 in step S2202a is denoted as IP2.

Step S2202b, F-CP1 sends user plane MBS conversation establishment request to F-UP12, F-UP12 feeds back user plane MBS conversation establishment response to F-CP 1. The process is similar to the process of step S1502 in the foregoing embodiment, and is not described again, wherein the IP multicast transport address allocated by the F-UP12 in step S2202b is denoted as IP3.

Step S2203, if F-UP11 and F-UP12 support to receive the data transmitted based on the multicast mode, apply for joining in the multicast transmission group corresponding to the IP multicast transmission address IP1 to receive MBS service data sent by the father user plane node of F-UP11 and F-UP 12.

After executing steps S2202a and S2202b, F-CP1 may choose to execute steps S2204a, S2204b, and S2204c as follows, and select user plane nodes F-UP21, F-UP22, and F-UP23 (the selection and number of user plane nodes by F-CP1 are merely examples), which aims to allow F-UP11 and F-UP12 to offload or optimize transmission through F-UP21, F-UP22, and F-UP 23.

For example, when the distance between the F-UP11 and the next level user plane node of the F-UP11 is long and the number of the next level user plane nodes of the F-UP11 is very large, if MBS service data is directly transmitted to the next level user plane node of the F-UP11 by the F-UP11, such transmission efficiency is very low. And by introducing the F-UP21, the F-UP22 and the like between the F-UP11 and the next-level user plane node of the F-UP11, the MBS service data can be sent to the next-level user plane node through the F-UF21 by the F-UP11, so that the data transmission efficiency can be effectively improved.

Step S2204a, step S2204b and step S2204c are described below:

in step S2204a, F-CP1 sends a user plane MBS session establishment request to F-UP21, and F-UP21 feeds back a user plane MBS session establishment response to F-CP 1. The process is similar to the process of step S1502 in the previous embodiment, and is not repeated. In step S2204a, the F-UP21 further allocates a new IP multicast transport address, identified as IP4 in this embodiment, for transmitting MBS service data to the sub user plane node of the F-UP 21. And, if the F-UP21 does not support receiving MBS service data transmitted by the F-UP11 in a multicast manner, the F-UP21 allocates an F-TEID to receive MBS service data from the F-UP11 in a point-to-point manner.

Step S2204b, F-CP1 sends user plane MBS conversation establishment request to F-UP22, F-UP22 feeds back user plane MBS conversation establishment response to F-CP 1. The process is similar to the process of step S1502 in the previous embodiment, and is not described again. In step S2104b, F-UP22 also allocates a new IP multicast transmission address, identified in this embodiment as IP5, for transmitting MBS service data to the sub-user plane nodes of F-UP 22. And, if F-UP22 does not support receiving MBS service data transmitted by F-UP11 in a multicast manner, F-UP22 may allocate an F-TEID to receive MBS service data from F-UP11 in a point-to-point manner.

It should be noted that, in an embodiment of the present application, the Multicast transmission address in the MBS IP Multicast Distribution included in the user plane MBS session establishment request in step S2204a and step S2204b is the Multicast transmission address IP2 in step S2202 a.

Step S2204c, F-CP1 sends user plane MBS conversation establishment request to F-UP23, F-UP23 feeds back user plane MBS conversation establishment response to F-CP 1. Meanwhile, the F-UP23 also allocates a new IP multicast transport address, which is identified as IP6 in this embodiment, for transmitting MBS service data to the sub user plane nodes of the F-UP 23. The process is similar to the process of step S1502 in the previous embodiment, and is not described again.

In an embodiment of the present application, the Multicast transmission address in the MBS IP Multicast Distribution included in the user plane MBS session establishment request in step S2204c is the Multicast transmission address IP3 in step S2202 b. Wherein the new multicast transmission address determined in step S2204c is IP6 of the sub-user plane node (i.e., S-UP31 and S-UP32 in fig. 22) allocated to F-UP23 by F-UP 23. And, if the F-UP23 does not support receiving MBS service data transmitted by the F-UP12 in a multicast manner, the F-UP23 assigns an F-TEID to receive MBS service data from the F-UP12 in a point-to-point manner.

In step S2205a, if F-UP21 and F-UP22 support receiving data transmitted based on multicast mode, apply for joining in the multicast transmission group corresponding to IP multicast transmission address IP2 to receive MBS service data sent by F-UP 11.

Step S2205b, if the F-UP23 supports receiving the data transmitted based on the multicast mode, applies for joining in the multicast transmission group corresponding to the IP multicast transmission address IP3 to receive the MBS service data sent by the F-UP 12.

In step S2206a, if there is a user plane node that does not support receiving multicast transmission but supports receiving MBS service data using a point-to-point manner in F-UP21 and F-UP22, F-CP1 sends a user plane MBS session modification request to F-UP11, and F-UP11 feeds back a user plane MBS session modification response to F-CP 1. Wherein, the user plane MBS conversation modifying request comprises F-TEID distributed by the user plane node which does not support receiving multicast transmission and supports receiving MBS service data by using a point-to-point mode in the F-UP21 and the F-UP22, so as to indicate the F-UP11 to increase to use the point-to-point mode to transmit the MBS service data to the user plane node which does not support receiving multicast transmission and supports receiving MBS service data by using the point-to-point mode in the F-UP21 and the F-UP 22.

It should be noted that: if F-CP1 does not allocate a lower-level user plane node for F-UP11, F-CP1 sends a user plane MBS session deletion request to F-UP11, F-UP11 sends an IGMP Leave data packet after receiving the user plane MBS session deletion request, and quits from the multicast transmission group indicated by the multicast transmission address IP1 allocated by the parent user plane node of F-UP11, and F-UP11 replies a user plane MBS session deletion response to F-CP1 (the process is not identified in the figure).

Step S2206b, if F-UP23 does not support receiving data transmitted based on multicast mode, but supports receiving MBS service data using point-to-point mode, F-CP1 sends user plane MBS session modification request to F-UP12, F-UP12 feeds back user plane MBS session modification response to F-CP 1. Wherein, the user plane MBS conversation modifying request comprises F-TEID allocated by F-UP23, so as to instruct F-UP12 to transmit MBS service data to F-UP23 in a point-to-point mode.

It should be noted that: if F-CP1 does not allocate a lower level user plane node for F-UP12, F-CP1 sends a user plane MBS session deletion request to F-UP12, F-UP12 sends an IGMP Leave data packet after receiving the user plane MBS session deletion request, and quits from the multicast transmission group indicated by the multicast transmission address IP1 allocated by the parent user plane node of F-UP12, and F-UP12 replies a user plane MBS session deletion response to F-CP1 (the process is not identified in the figure).

In step S2207, the F-CP1 sends an MBS session starting request to the sub control surface node S-CP1 of the F-CP1 according to the information of the sub control surface node of the F-CP 1.

The MBS session starting request sent by the F-CP1 to the sub control plane node S-CP1 of the F-CP1 comprises the following parameters: TMGI, MBS Session Duration, MBS QFISs, qoS Profile, MBS Time to Data Transfer, list of { F-UP ID, MBS transmission information }, MBS Service Area. The MBS transmission information is MBS IP Multicast Distribution (C-TEID). In this embodiment, the List of { F-UP ID, MBS transmission information } includes the MBS IP Multicast Distribution corresponding to the F-UP21 ID and the F-UP21 ID, and the MBS IP Multicast Distribution corresponding to the F-UP22 ID and the F-UP22 ID. The MBS IP Multicast Distribution corresponding to the F-UP21 ID is allocated by the F-UP21, wherein the included IP Multicast transport address is the new IP Multicast transport address IP4 allocated by the F-UP21 in step S2204 a; the MBS IP Multicast Distribution corresponding to the F-UP22 ID is allocated by the F-UP22, wherein the included IP Multicast transport address is the new IP Multicast transport address IP5 allocated by the F-UP22 in step S2204b, and the new IP Multicast transport address IP4 allocated by the F-UP21 in step S2204a is different from the new IP Multicast transport address IP5 allocated by the F-UP22 in step S2204 b.

In step S2208, after receiving the MBS session start request sent by F-CP1, S-CP1 performs the user plane MBS session establishment procedure. Specifically, S-CP1 selects one or more S-UPs for F-UP21 and selects several S-UPs for F-UP22 from among a plurality of S-UPs according to information of the sub-control plane node of S-CP1, and in this embodiment, it is assumed that S-UP11 and S-UP12 are selected for F-UP21 and no sub-user plane node is selected for F-UP 22. Then S-CP1 sends user plane MBS conversation establishing request to S-UP11 and S-UP12, and receives user plane MBS conversation establishing response fed back by S-UP11 and S-UP 12. Meanwhile, if S-UP11 and S-UP12 support receiving multicast transmission, the multicast transmission group corresponding to the new IP multicast transmission address IP4 allocated in step S2204a by the F-UP21 may be added to receive MBS service data sent by the F-UP 21; if some sub-user plane nodes in S-UP11 and S-UP12 do not support receiving data transmitted based on multicast mode but support receiving MBS service data using point-to-point mode, the user plane nodes in S-UP11 and S-UP12 that do not support receiving data transmitted based on multicast mode but support receiving MBS service data using point-to-point mode may allocate F-TEID to receive MBS service data transmitted by F-UP21 using point-to-point mode, the specific procedure is similar to step S1505a and step S1506, and is not described again.

In step S2209, the S-CP1 sends an MBS session start response to the F-CP 1. If the S-UP does not support receiving the data transmitted based on the Multicast mode but supports receiving the MBS service data by using the point-to-point mode, the MBS conversation starting response comprises the F-TEID distributed by the S-UP and corresponds to the F-UP, thereby forming a List of { F-UP ID, list of F-TEIDsup, multicast Enable }. In this embodiment, list of { F-UP ID, list of F-TEIDsup, multicast Enable } contains List of F-TEIDsup and Multicast Enable for F-UP21, and List of F-TEIDsup and Multicast Enable for F-UP 22. Since S-CP1 did not select a child user plane node for F-UP22, no F-TEID is contained in the List of F-TEIDs for F-UP22, and the Multicast Enable value for F-UP22 is Disable. Or the MBS session start response sent by S-CP1 to F-CP1 has no List of F-TEIDsup for F-UP22 and the Multicast Enable value for F-UP22 is Disable. Of course, the S-CP1 may also indicate that the sub-user plane node is not selected to the F-UP22 by returning a Failure Code (such as Failed List { F-UP22 }) in the MBS session start response.

Similar to step S1507, since some S-UP support receiving multicast-based data and some other S-UP does not support receiving multicast-based data, list F-TEIDsup for F-UP21 corresponds only to those S-UP which do not support receiving multicast transmission but support receiving MBS service data using point-to-point, and the other description refers to the relevant contents of step S1507.

In step S2210a, F-CP1 sends a user plane MBS session modification request to F-UP21 according to List of { F-UP ID, list of F-TEIDsup, multicast Enable } contained in MBS session start response fed back by S-CP1, and F-UP21 feeds back user plane MBS session modification response to F-CP 1. The detailed description of this step is similar to that of step S1508, and is not repeated here.

It should be noted that: if the F-CP1 determines that the F-UP21 is not allocated any lower level user plane node, the F-CP1 sends a user plane MBS session deletion request to the F-UP21, after receiving the user plane MBS session deletion request, sends an IGMP Leave packet and exits from the multicast transmission group indicated by the multicast transmission address IP2 allocated by the F-UP11, and the F-UP21 replies a user plane MBS session deletion response to the F-CP1 (this process is not identified in the figure).

In step S2210b, after receiving MBS session start responses replied by all the sub-control surface nodes of F-CP1, F-CP1 determines that all the sub-control surface nodes of F-CP1 do not select a sub-user surface node for F-UP22, F-CP1 sends a user surface MBS session deletion request to F-UP22, F-UP22 sends an IGMP Leave packet after receiving the user surface MBS session deletion request, deletes from the multicast transmission group indicated by multicast transmission address IP2 allocated by F-UP11, and F-UP22 replies a user surface MBS session deletion response to F-CP 1.

In step S2211, the F-CP1 sends an MBS conversation starting request to the sub control surface node S-CP2 of the F-CP1 according to the information of the sub control surface node of the F-CP 1.

The MBS session start request sent by the F-CP1 to the sub-control plane node S-CP2 of the F-CP1 comprises the following parameters: TMGI, MBS Session Duration, MBS QFISs, qoS Profile, MBS Time to Data Transfer, list of { F-UP ID, MBS transmission information }, MBS Service Area. The MBS transmission information is MBS IP Multicast Distribution (C-TEID). In this embodiment, the List of { F-UP ID, MBS transmission information } includes the F-UP23 ID and the MBS IP Multicast Distribution corresponding to the F-UP23 ID. The MBS IP Multicast Distribution corresponding to the F-UP23 ID is allocated by the F-UP23, wherein the included IP Multicast transport address is the new IP Multicast transport address IP6 allocated by the F-UP23 in step S2204 c.

It should be noted that: there is no precedence relationship between step S2211 and step S2207, and they may be steps executed by F-CP1 in parallel respectively.

In step S2212, after receiving the MBS session start request sent by F-CP1, S-CP2 performs the user plane MBS session establishment procedure. Specifically, the S-CP2 selects one or more S-UPs for the F-UP23 from the plurality of S-UPs according to the information of the sub-control plane node of the S-CP2, and in this embodiment, it is assumed that S-UP31 and S-UP32 are selected for the F-UP23, that is, the sub-user plane node selected for the F-UP23 is different from the sub-user plane node selected for the F-UP21 and the F-UP 22. Then S-CP2 sends user plane MBS conversation establishment request to the sub user plane node (i.e. S-UP31 and S-UP 32) selected for F-UP23, and receives user plane MBS conversation establishment response fed back by S-UP31 and S-UP 32. Meanwhile, if S-UP31 and S-UP32 support receiving multicast transmission, a multicast transmission group corresponding to the new IP multicast transmission address IP6 allocated by F-UP23 in step S2204c may be added to receive MBS service data sent by F-UP 23; if some sub-user plane nodes in S-UP31 and S-UP32 do not support receiving data transmitted based on multicast mode but support receiving MBS service data using point-to-point mode, the sub-user plane nodes in S-UP31 and S-UP32 that do not support receiving data transmitted based on multicast mode but support receiving MBS service data using point-to-point mode may allocate F-TEID to receive MBS service data transmitted by F-UP23 using point-to-point mode, the specific procedure is similar to step S1505a and step S1506, and is not described again.

In step S2213, S-CP2 sends an MBS session start response to F-CP 1. If one of S-UP31 and S-UP32 does not support receiving Multicast-based data but supports receiving MBS service data using a point-to-point manner, the MBS session start response includes the S-UP-allocated F-TEID and corresponds to the F-UP, thereby forming a List of { F-UP ID, list of F-TEIDsup, multicast Enable }. In this embodiment, list of { F-UP ID, list of F-TEIDsup, multicast Enable } contains List of F-TEIDsup and Multicast Enable for F-UP 23.

Similar to step S1507, since some S-UPs support receiving data transmitted based on multicast and some other S-UPs do not support receiving data transmitted based on multicast, this List F-TEIDsup corresponds only to those S-UPs that do not support receiving multicast transmission but support receiving MBS service data using point-to-point. Therefore, when all S-UPs of an F-UP support receiving data transmitted based on multicast, the List of F-TEIDsup corresponding to the F-UP is not available, and other descriptions refer to the related contents of step S1507.

In addition, when S-CP2 decides not to assign any sub-user plane node to one/some F-UP ID (S), then Multicast Enable corresponding to the/these F-UP ID (S) can be set to Disable. Of course, failed List { F-UP } may also be employed in the MBS session start response to indicate the F-UP to which no child user plane node is allocated.

In step S2214, F-CP1 sends a user plane MBS session modification request to F-UP23 according to List of { F-UP ID, list of F-TEIDsup, multicast Enable } contained in the MBS session start response fed back by S-CP2, and F-UP23 feeds back the user plane MBS session modification response to F-CP 1. The detailed description of this step is similar to that of step S1508, and is not repeated here.

It should be noted that: if the F-CP1 determines that the F-UP23 is not allocated any lower level user plane node, the F-CP1 sends a user plane MBS session deletion request to the F-UP23, after receiving the user plane MBS session deletion request, sends an IGMP Leave packet and exits from the multicast transmission group indicated by the multicast transmission address IP3 allocated by the F-UP12, and the F-UP23 replies a user plane MBS session deletion response to the F-CP1 (this process is not identified in the figure).

Step S2215, after the F-CP1 receives the MBS session start responses fed back by all the S-CPs, the F-CP1 sends the MBS session start response to the father control surface node of the F-CP1 according to the MBS session start responses fed back by all the S-CPs.

Similar to step S1609, the MBS session start response replied by F-CP1 to the F-CP1 parent control plane node contains the UP ID (which is the identity of the user plane node that is sibling to the F-CP1 parent control plane node), and possibly also the List of F-TEIDfup and Multicast Enable.

As can be seen from steps S2201 to S2215, in the embodiment of the present application, F-CP1 has two sub-control plane nodes S-CP1 and S-CP2, F-CP1 selects the next-level user plane nodes F-UP21 and F-UP22 for F-UP11, F-CP1 selects the next-level user plane node F-UP23 for F-UP12, S-CP1 selects the sub-user plane nodes S-UP11 and S-UP12 for F-UP21, and S-CP2 selects the sub-user plane nodes S-UP31 and S-UP32 for F-UP 23. Meanwhile, since S-CP1 does not select a sub-user plane node for F-UP22, F-UP22 needs to be deleted from the user plane MBS transmission tree.

It should be noted that: in the process of establishing the user plane MBS session, a user plane node may be simultaneously sent by two control plane nodes to establish the user plane MBS session request message, or the user plane MBS session establishment request message sent by another control plane node is received after being selected by one control plane node. If a user plane node receives a user plane MBS session establishment request message sent by two control plane nodes (certainly, there may be more, two are taken as examples here), the user plane node may normally respond to the user plane MBS session establishment request sent by one of the control plane nodes in the user plane MBS session establishment response message, and Reject (Reject) the other control plane node in the other user plane MBS session establishment response message to indicate that the user plane node has been selected. If a user plane node has a father user plane node through a control plane node and receives a user plane MBS conversation establishing request message sent by another control plane node, the other control plane node is objected in another user plane MBS conversation establishing response message to indicate that the user plane node has been selected.

After the establishment of the MBS session transmission tree is completed, the following steps may be performed:

in step S2216a, the F-UP11 receives the downlink MBS service data sent by the parent user plane node of the F-UP 11. And then transmits the received downlink MBS service data to the F-UP21 through step S2217 a. F-UP21 transmits the received downlink MBS service data to S-UP11 and S-UP12 through step S2218 a. Each user plane node transmits MBS service data in the multicast transmission mode or the point-to-point transmission mode determined in the previous step, and simultaneously each user plane node receives the MBS service data in the multicast transmission mode or the point-to-point transmission mode determined in the previous step.

In step S2216b, the F-UP12 receives the downlink MBS service data sent by the parent user plane node of the F-UP 12. The received downlink MBS service data is then transmitted to the F-UP23 through step S2217c, and the F-UP23 transmits the received downlink MBS service data to the S-UP31 and S-UP32 through step S2218 c. Each user plane node transmits MBS service data in the multicast transmission mode or the point-to-point transmission mode determined in the previous step, and simultaneously each user plane node receives the MBS service data in the multicast transmission mode or the point-to-point transmission mode determined in the previous step.

Furthermore, section 5.3.4.2.2 of standard TS23.501 defines the architecture of one or more I-SMFs participating in one PDU session with one or more I-UPFs (Intermediate-UPFs) in a non-roaming scenario. For a non-roaming PDU session, there is only one SMF. If there are multiple SMFs, the SMF controlling the PSA is still referred to as the SMF for consistency with the specification, and the other SMFs are referred to as I-SMFs. Where the names of UPFs controlled by SMFs are unchanged, they are still referred to as UPFs, while UPFs controlled by I-SMFs are referred to as I-UPFs.

In this situation, the embodiment of the present application proposes that the I-SMF and the I-UPF may participate in the MBS session, and a process of specifically establishing the user plane MBS transmission tree may be as shown in fig. 23, including the following steps:

in step S2301, F-CP1 receives an MBS session start request sent by the parent control plane node of F-CP 1. The specific process is similar to step S1501 and will not be described again. Wherein, the IP Multicast transmission address contained in the MBS IP Multicast Distribution in the MBS session start request is recorded as IP1.

After receiving the MBS session start request sent by the parent control plane node of the F-CP1, the F-CP1 may determine to select one or more F-UPFs from the multiple F-UPFs as user plane nodes of the same level as the F-CP1 according to the information of the child control plane nodes of the F-CP1, where in this embodiment, it is assumed that two user plane nodes are selected and denoted as F-UP11 and F-UP12. Then step S2302a and step S2302b are performed, respectively.

In step S2302a, F-CP1 sends a user plane MBS session establishment request to F-UP11, and F-UP11 feeds back a user plane MBS session establishment response to F-CP 1. The process is similar to the process of step S1502 in the foregoing embodiment, and is not described again, wherein the IP multicast transport address allocated by F-UP11 in step S2302a is denoted as IP2.

Step S2302b, F-CP1 sends user plane MBS session establishment request to F-UP12, and F-UP12 feeds back user plane MBS session establishment response to F-CP 1. The process is similar to the process of step S1502 in the foregoing embodiment, and is not described again, wherein the IP multicast transport address allocated by the F-UP12 in step S2302b is denoted as IP3.

Step S2303, if F-UP11 and F-UP12 support receiving data transmitted based on multicast mode, apply for joining in the multicast transmission group corresponding to IP multicast transmission address IP1 to receive MBS service data sent by the father user plane node of F-UP11 and F-UP 12.

Then, the F-CP1 determines that the UPF managed by the F-CP1 and the UPF managed by the sub-control plane node of the F-CP1 can not directly establish a transmission path according to the service area information of the sub-control plane node (usually NR base station) of the F-CP1, and the F-CP1 selects an I-SMF, wherein the selected I-SMF can communicate with the F-CP1 and the sub-control plane node of the F-CP 1. In this embodiment, it is assumed that one I-SMF is selected, and then step S2304 is performed.

In step S2304, F-CP1 sends an MBS session start Request (i.e., nscp _ MBSSesserstartrequest) to the I-SMF.

The MBS session start request sent by the F-CP1 to the I-SMF comprises the following parameters: TMGI, MBS Session Duration, list of S-CP, MBS QFIs, qoS Profile, MBS Time to Data Transfer, list of { F-UP ID, MBS transmission information }, MBS Service Area. The reason why the F-CP1 includes the sub-control plane node information List of S-CP provided by the F-CP1 in the MBS session start request sent to the I-SMF is mainly because the I-SMF is dynamically selected by the F-CP1 and then added to MBS service management, and the I-SMF does not have any information of MBS UE Context (for MBS multicast service) or user plane node. In this embodiment, the List of { F-UP ID, MBS Transport Information } contains only the F-UP11 ID and the MBS IP Multicast Distribution corresponding to the F-UP11 ID. The MBS IP Multicast Distribution corresponding to the F-UP11 ID is allocated by the F-UP11, which includes the new IP Multicast transport address IP2 and the C-TEID allocated by the F-UP11 in step S2302 a.

The I-SMF determines and selects the I-UPF11, the I-UPF12, the I-UPF21 and the I-UPF22 according to the service area of the F-CP1 matched by the query or the network and the service area of the List of S-CP provided by the F-CP1 based on the received MBS session start request after receiving the MBS session start request. Then, step S2305a and step S2305b are performed.

In step S2305a, the I-SMF sends user plane MBS session establishment requests to the I-UPF11 and the I-UPF12 respectively, and the I-UPF11 and the I-UPF12 feed back user plane MBS session establishment responses to the I-SMF respectively. The process is similar to the process of step S1502 in the previous embodiment, and is not described again. In step S2305a, the I-UPF11 and the I-UPF12 respectively allocate new IP multicast transport addresses, which are respectively denoted as IP4 and IP5 in this embodiment, and the new IP multicast transport address IP4 allocated by the I-UPF11 is used for transmitting MBS service data to a lower-level user plane node of the I-UPF11 (i.e., the I-UPF21 in fig. 23); the new IP multicast transport address IP5 assigned by the I-UPF12 is used for transmitting MBS service data to a lower user plane node of the I-UPF12, i.e., the I-UPF22 in fig. 23. And, if the I-UPF11 does not support receiving MBS service data transmitted by the F-UP11 in a multicast manner, the I-UPF11 allocates an F-TEID to receive MBS service data from the F-UP11 in a point-to-point manner; similarly, if the I-UPF12 does not support receiving MBS service data transmitted by the F-UP11 in a multicast manner, the I-UPF12 assigns a F-TEID to receive MBS service data from the F-UP11 in a point-to-point manner.

In step S2305b, the I-SMF sends user plane MBS session establishment requests to the I-UPF21 and the I-UPF22 respectively, and the I-UPF21 and the I-UPF22 feed back user plane MBS session establishment responses to the I-SMF respectively. The process is similar to the process of step S1502 in the previous embodiment, and is not described again. Wherein, in step S2305a, the I-UPF21 and the I-UPF22 respectively allocate new IP multicast transport addresses, which are respectively denoted as IP6 and IP7 in this embodiment, and the new IP multicast transport address IP6 allocated by the I-UPF21 is used for transmitting MBS service data to the sub-user plane nodes (i.e., S-UP11 and S-UP12 in fig. 23) of the I-UPF 21; the new IP multicast transport address IP7 allocated by the I-UPF22 is used for transporting MBS service data to the sub user plane nodes (i.e., S-UP21 and S-UP22 in fig. 23) of the I-UPF 22. And, if the I-UPF21 does not support receiving the MBS service data transmitted by the I-UPF11 in a multicast manner, the I-UPF21 allocates an F-TEID to receive the MBS service data from the I-UPF11 in a point-to-point manner; similarly, if the I-UPF22 does not support receiving MBS service data sent by the I-UPF12 in a multicast manner, the I-UPF22 assigns a F-TEID to receive MBS service data from the I-UPF12 in a point-to-point manner.

It should be noted that, in an embodiment of the present application, the IP Multicast transmission address in the MBS IP Multicast Distribution included in the user plane MBS session establishment request in step S2305a is the IP Multicast transmission address IP2 allocated by F-UP11 in step S2302 a. And the IP Multicast transmission addresses in the MBS IP Multicast Distribution included in the user plane MBS session establishment requests for the I-UPF21 and the I-UPF22 in the step S2305b are the IP Multicast transmission addresses IP4 and IP5 (IP 4 is different from IP 5) allocated to the I-UPF11 and the I-UPF12 in the step S2305a, respectively. And in FIG. 23, for layout reasons, I-UPF11 and I-UPF12 are drawn together, I-UPF21 and I-UPF22 are drawn together, S-UP11 and S-UP12 are drawn together, and S-UP21 and S-UP22 are drawn together.

In step S2306a, if the I-UPF11 and the I-UPF12 support receiving data transmitted based on a multicast mode, apply for joining in a multicast transmission group corresponding to the IP multicast transmission address IP2 to receive MBS service data sent by the F-UP 11.

Step S2306b, if the I-UPF21 supports receiving the data transmitted based on the multicast mode, applying for joining the multicast transmission group corresponding to the IP multicast transmission address IP4 to receive the MBS service data sent by the I-UPF 11. And if the I-UPF22 supports the reception of the data transmitted based on the multicast mode, applying for the addition to a multicast transmission group corresponding to the IP multicast transmission address IP5 to receive the MBS service data sent by the I-UPF 12.

In step S2307, the I-SMF sends an MBS session start request to the child control plane node S-CP1 provided by F-CP 1.

The MBS session start request sent by the I-SMF to the S-CP1 comprises the following parameters: TMGI, MBS QFIs, qoS Profile, list of { I-UPF ID, MBS transmission information }, MBS Service Area. In this embodiment, the List of { I-UPF ID, MBS transmission information } includes the IDs corresponding to I-UPF21 and I-UPF22, respectively, and the MBS transmission information corresponding to I-UPF21 and I-UPF22, respectively. The IP multicast transmission address contained in the MBS transmission information corresponding to the I-UPF21 is IP6, the IP multicast transmission address contained in the MBS transmission information corresponding to the I-UPF22 is IP7, and the IP6 is different from the IP 7.

In step S2308, S-CP1 performs the user plane MBS session establishment process after receiving the MBS session start request sent by the I-SMF. Specifically, S-CP1 selects one or more S-UP for I-UPF21 and one or more S-UP for I-UPF22 from a plurality of S-UP, assuming in this embodiment that S-CP1 selects S-UP11 and S-UP12 for I-UPF21 and S-UP22 for I-UPF 22. Then S-CP1 sends user plane MBS conversation establishing request to S-UP11, S-UP12, S-UP21 and S-UP22, respectively, and receives user plane MBS conversation establishing response fed back by S-UP11, S-UP12, S-UP21 and S-UP22, respectively. Meanwhile, if the S-UP11 and the S-UP12 support receiving the data transmitted based on the multicast mode, the multicast transmission group corresponding to the IP multicast transmission address IP6 allocated by the I-UPF21 can be added to receive the MBS service data transmitted by the I-UPF 21; if S-UP21 and S-UP22 support receiving multicast transmission, the multicast transmission group corresponding to the IP multicast transmission address IP7 allocated by the I-UPF22 may be added to receive MBS service data sent by the I-UPF22, and the specific process is similar to step S1505a and step S1506 and is not described again.

In step S2309, S-CP1 sends an MBS session start response to the I-SMF. If one of S-UP11, S-UP12, S-UP21 and S-UP22 does not support receiving data transmitted based on Multicast mode but supports receiving MBS service data using point-to-point mode, the MBS session start response sent by S-CP1 to I-SMF contains the F-TEID allocated by S-UP and corresponds to the corresponding I-UPF, thus forming a List of { I-UPF ID, list of F-TEID, multicast Enable }. In this embodiment, list of { I-UPF ID, list of F-TEIDsup, multicast Enable } contains List of F-TEIDsup and Multicast Enable for I-UPF21, I-UPF22, respectively.

Similar to step S1507, since some S-UPs support receiving data transmitted based on multicast and some S-UPs do not support receiving data transmitted based on multicast, this List F-TEIDsup only corresponds to those S-UPs that do not support receiving multicast transmission but support receiving MBS service data using point-to-point, and the other description refers to the relevant contents of step S1507.

In addition, when the S-CP1 decides not to allocate any sub-user plane node to a certain I-UPF ID/IDs, the Multicast Enable corresponding to the I-UPF ID/IDs can be set to Disable. Of course, a Failed List { I-UPF } may also be employed in the MBS session start response to indicate I-UPFs for which no child user plane node is allocated.

In step S2310a, the I-SMF sends a user plane MBS session modification request to the I-UPF21/22 according to the List of { I-UPF ID, list of F-TEIDsup, multicast Enable } contained in the MBS session start response fed back by the S-CP1, and the I-UPF21/22 feeds back the user plane MBS session modification response to the I-SMF. The detailed description of this step is similar to that of step S1508, and is not repeated here.

It should be noted that: if the I-SMF determines that the I-UPF21 is not allocated any lower level user plane node, the I-SMF sends a user plane MBS session deletion request to the I-UPF21, after receiving the user plane MBS session deletion request, issues an IGMP Leave packet, exits from the multicast transmission group indicated by the multicast transmission address IP4 allocated by the I-UPF11, and the I-UPF21 replies a user plane MBS session deletion response to the I-SMF (this process is not identified in the figure).

If the I-SMF determines that the I-UPF22 is not allocated any lower level user plane node, the I-SMF sends a user plane MBS session deletion request to the I-UPF22, after receiving the user plane MBS session deletion request, issues an IGMP Leave packet, exits from the multicast transmission group indicated by the multicast transmission address IP5 allocated by the I-UPF12, and the I-UPF22 replies a user plane MBS session deletion response to the I-SMF (this process is not identified in the figure).

Step S2310b, if the I-SMF determines that the I-UPF21 does not support the MBS service data sent by the I-UPF11 in a multicast mode but supports the point-to-point mode to receive the MBS service data sent by the I-UPF11 in the process of establishing the MBS session with the I-UPF21 and the I-UPF22 in the step S2305b, the I-SMF sends a user plane MBS session modification request to the I-UPF11, and the I-UPF11 feeds back a user plane MBS session modification response to the I-SMF. Similarly, if the I-SMF determines that the I-UPF22 does not support the MBS service data transmitted by the I-UPF12 through the multicast manner but supports the point-to-point manner reception according to the determination in the step S2305b that the MBS session is established with the I-UPF21 and the I-UPF22, the I-SMF 12 sends a user plane MBS session modification request to the I-UPF12, and the I-UPF12 feeds back a user plane MBS session modification response to the I-SMF.

It should be noted that: if the I-SMF does not allocate any lower level user plane node to the I-UPF11 or the I-UPF12, the I-SMF sends a user plane MBS session deletion request to the I-UPF11 or the I-UPF12, the I-UPF11 or the I-UPF12 sends an IGMP Leave packet after receiving the user plane MBS session deletion request, exits from the multicast transmission group indicated by the multicast transmission address IP2 allocated by the F-UP11, and the I-UPF11 or the I-UPF12 replies a user plane MBS session deletion response to the I-SMF (the process is not identified in the figure).

In step S2311, the I-SMF sends an MBS session start response to the F-CP 1. If one of the I-UPF11 and I-UPF12 does not support receiving data transmitted by Multicast but supports receiving MBS service data by point-to-point method, the MBS session start response sent by the I-SMF to the F-CP1 contains the F-TEID allocated by the I-UPF and corresponds to F-UP11, thus forming a List of { F-UP ID, list of F-TEIDiupf, multicast Enable }. In this embodiment, list of { F-UP ID, list of F-TEIDiupf, multicast Enable } contains List of F-TEIDifufp and Multicast Enable for F-UP 11.

Similar to step S1507, since some I-UPFs support receiving data transmitted based on multicast and some other I-UPFs do not support receiving data transmitted based on multicast, this List F-TEIDiupf only corresponds to those I-UPFs that do not support receiving multicast transmission but support receiving MBS service data using point-to-point, and other descriptions refer to the relevant contents of step S1507.

Step S2312, if there is an I-UPF which does not support receiving multicast transmission but supports receiving MBS service data in a point-to-point manner in the I-UPF11 and the I-UPF12, the F-CP1 sends a user plane MBS session modification request to the F-UP11, and the F-UP11 feeds back a user plane MBS session modification response to the F-CP 1. The user plane MBS conversation modifying request sent by the F-CP1 to the F-UP11 comprises F-TEID of I-UPF which does not support receiving multicast transmission but supports receiving MBS service data by using a point-to-point mode in I-UPF11 and I-UPF12, and the MBS service data is transmitted to the I-UPF which does not support receiving multicast transmission but supports receiving the MBS service data by using the point-to-point mode in the I-UPF11 and the I-UPF12 by indicating the F-UP11 to increase using the point-to-point mode.

It should be noted that: if the F-CP1 determines that the F-UP11 is not allocated any lower-level user plane node, the F-CP1 sends a user plane MBS session deletion request to the F-UP11, the F-UP11 sends an IGMP Leave data packet after receiving the user plane MBS session deletion request, and exits from the multicast transmission group indicated by the multicast transmission address IP1 allocated by the parent user plane node of the F-UP11, and the F-UP11 replies a user plane MBS session deletion response to the F-CP1 (the process is not identified in the figure).

And step S2313, the F-CP1 sends an MBS conversation starting request to the sub control surface node S-CP2 of the F-CP1 according to the information of the sub control surface node of the F-CP 1.

The MBS session start request sent by the F-CP1 to the child control plane node S-CP2 of the F-CP1 comprises the following parameters: TMGI, MBS Session Duration, MBS QFISs, qoS Profile, MBS Time to Data Transfer, list of { F-UP ID, MBS transmission information }, MBS Service Area. The MBS transmission information is MBS IP Multicast Distribution (C-TEID). In this embodiment, the List of { F-UP ID, MBS transmission information } includes the F-UP12 ID and the MBS IP Multicast Distribution corresponding to the F-UP12 ID. The MBS IP Multicast Distribution corresponding to the F-UP12 ID is allocated by the F-UP12, wherein the included IP Multicast transport address is the new IP Multicast transport address IP3 allocated by the F-UP12 in step S2302 b.

It should be noted that: step S2313 and step S2304 have no precedence relationship therebetween, and they may be steps executed by the F-CP1 in parallel respectively.

Step S2314, after receiving the MBS session starting request sent by the F-CP1, the S-CP2 performs the user plane MBS session establishment process. Specifically, S-CP2 selects one or more S-UPs for F-UP12 from among a plurality of S-UPs based on information of the S-CP 2' S child control plane node, assuming in this embodiment that S-UPs 31 and S-UPs 32 are selected for F-UP 12. Then S-CP2 sends user plane MBS conversation establishment request to S-UP31 and S-UP32, respectively, and receives user plane MBS conversation establishment response fed back by S-UP31 and S-UP32, simultaneously if S-UP31 and S-UP32 support receiving multicast transmission, multicast transmission group corresponding to new IP multicast transmission address IP3 allocated by F-UP12 in step S2302b can be added to receive MBS service data sent by F-UP 12; if some sub-user plane nodes in S-UP31 and S-UP32 do not support receiving data transmitted based on multicast mode but support receiving MBS service data using point-to-point mode, the sub-user plane nodes in S-UP31 and S-UP32 that do not support receiving data transmitted based on multicast mode but support receiving MBS service data using point-to-point mode may allocate F-TEID to receive MBS service data transmitted by F-UP12 using point-to-point mode, the specific procedure is similar to step S1505a and step S1506, and is not described again.

At step S2315, the S-CP2 sends an MBS session start response to the F-CP 1. If one of S-UP31 and S-UP32 supports the reception of data transmitted by Multicast but supports the reception of MBS service data by point-to-point, the MBS session start response sent by S-CP2 to F-CP1 contains the F-TEID allocated by S-UP and corresponds to F-UP, thus forming a List of { F-UP ID, list of F-TEIDsup, multicast Enable }. In this embodiment, list of { F-UP ID, list of F-TEIDsup, multicast Enable } contains List of F-TEIDsup and Multicast Enable for F-UP 12.

Similar to step S1507, since some S-UPs support receiving data transmitted based on multicast and some other S-UPs do not support receiving data transmitted based on multicast, this List F-TEIDsup only corresponds to those S-UPs that do not support receiving multicast transmission but support receiving MBS service data using point-to-point, and other descriptions refer to the relevant contents of step S1507.

In step S2316, F-CP1 sends a user plane MBS session modification request to F-UP12 according to the List of { F-UP ID, list of F-TEIDsup, multicast Enable } contained in the MBS session start response fed back by S-CP2, and F-UP12 feeds back the user plane MBS session modification response to F-CP 1. The detailed description of this step is similar to that of step S1508, and is not repeated here.

It should be noted that: if F-CP1 determines that F-UP12 is not allocated any lower level user plane node, F-CP1 sends a user plane MBS session deletion request to F-UP12, after receiving the user plane MBS session deletion request, sends an IGMP Leave packet and exits from the multicast transmission group indicated by the multicast transmission address IP1 allocated by the parent user plane node of F-UP12, and F-UP12 replies a user plane MBS session deletion response to F-CP1 (the process is not identified in the figure).

Step S2317, after the F-CP1 receives the MBS session start response fed back by all the sub-control surface nodes of the F-CP1, the F-CP1 sends the MBS session start response to the father control surface node of the F-CP1 according to the MBS session start response fed back by all the sub-control surface nodes of the F-CP 1.

Similar to step S1609, the MBS session start response replied by F-CP1 to the F-CP1 parent control plane node contains the UP ID (which is the identity of the user plane node that is sibling to the F-CP1 parent control plane node), and possibly also the List of F-TEIDfup and Multicast Enable.

As can be seen from steps S2301 to S2315, in the embodiment of the present application, the F-CP1 has two sub-control plane nodes S-CP1 and S-CP2, the F-CP1 selects the I-SMF, the I-SMF selects the first-level intermediate user plane nodes I-UPF11 and I-UPF12, and selects the second-level intermediate user plane nodes I-UPF21 and I-UPF22. Meanwhile, S-CP1 selects S-UP11 and S-UP12 for I-UPF21 and S-UP22 for I-UPF 22; S-CP2 selects S-UP31 and S-UP32 for F-UP 12.

It should be noted that: in the process of establishing the user plane MBS session, there may be a case where one intermediate user plane node receives two user plane MBS session establishment requests at the same time (certainly, there may be more, which is described here by taking two as an example), for example, the same I-SMF sends two user plane MBS session establishment requests (corresponding to the case where different control plane nodes select the same I-SMF), or two different I-SMFs respectively send one user plane MBS session establishment request (corresponding to the case where different control plane nodes select different I-SMFs), in this case, the intermediate user plane node may normally respond to one of the user plane MBS session establishment requests, and Reject (Reject) another control plane node in a response message to the other user plane MBS session establishment request, so as to indicate that the user plane node has been selected.

If an intermediate user plane node has a father user plane node through a user plane MBS conversation establishing request and receives another user plane MBS conversation establishing request, the object another control plane node is in the response message of the another user plane MBS conversation establishing request to indicate that the user plane node has been selected.

After the establishment of the MBS session transmission tree is completed, the following steps may be performed:

in step S2318a, the F-UP11 receives the downlink MBS service data sent by the parent user plane node of the F-UP 11. Then, the received downlink MBS service data is transmitted to the I-UPF11 and the I-UPF12 through step S2319a, the I-UPF11 transmits the downlink MBS service data sent by the F-UP11 to the I-UPF21, and the I-UPF12 transmits the downlink MBS service data sent by the F-UP11 to the I-UPF22. The I-UPF21 transmits the received downlink MBS service data to the S-UP11 and the I-UPF12, and the I-UPF22 transmits the received downlink MBS service data to the S-UP21 and the I-UPF22. Each user plane node transmits MBS service data in the multicast transmission mode or the point-to-point transmission mode determined in the previous step, and simultaneously each user plane node receives the MBS service data in the multicast transmission mode or the point-to-point transmission mode determined in the previous step.

In step S2318b, the F-UP12 receives the downlink MBS service data sent by the parent user plane node of the F-UP 12. And then transmits the received downlink MBS service data to the S-UP31 and S-UP32 through step S2319 b. Each user plane node transmits MBS service data in the multicast transmission mode or the point-to-point transmission mode determined in the previous step, and simultaneously each user plane node receives the MBS service data in the multicast transmission mode or the point-to-point transmission mode determined in the previous step.

In the technical solution of the above embodiment of the present application, F-CP is used to represent a parent control plane node, F-UP is used to represent a parent user plane node, S-CP is used to represent a child control plane node, and S-UP is used to represent a child user plane node. In the system architecture shown in fig. 10, SMF may be replaced by F-CP and UPF by F-UP, in which case S-CP is combined with S-UP to replace the access network node.

In the system architecture shown in FIG. 11, when MBSF can be replaced by F-CP and MBSU can be replaced by F-UP, in this case MB-SMF can be replaced by S-CP and MB-UPF can be replaced by S-UP. Or MB-SMF may be replaced by F-CP and MB-UPF by F-UP, in which case S-CP is combined with S-UP to replace NG-RAN.

It should be noted that: FIGS. 10 and 11 show basic architecture diagrams of two 5G MBS's in which enhancements may be made, such as multiple UPFs, multiple SMFs for the architecture shown in FIG. 10; for the architecture shown in FIG. 11, there may be more than one MB-SMF and more than one MB-UPF. When additional UPF or MB-UPF occurs, the technical solution shown in fig. 21 or fig. 22 may be adopted to establish the user plane MBs session tree; when additional MB-SMFs or SMFs occur (at this time, additional UPFs must occur), the technical solution shown in fig. 23 may be adopted to establish a user plane MBs session tree.

The technical scheme of the embodiment of the application realizes the establishment process of the user plane MBS session, can prevent the transmission loop of the user plane MBS session and avoid the problem of branch breakage in the transmission tree of the user plane MBS session. Meanwhile, the problem that the same father control surface simultaneously provides a plurality of father user surface nodes when the control surface is separated from the user surface in the user surface MBS conversation establishing process can be solved. In addition, the transmission of parent and child can be formed by managing different user plane nodes by the same control plane node, the user plane transmission resource is optimized, and when the user plane transmission which can not establish direct connection between the parent user plane node and the base station is established in the user plane MBS conversation establishing process, the I-SMF and the I-UPF are discovered and inserted to complete the establishment of the user plane transmission tree, and the optimization of the user plane transmission resource is effectively realized.

Embodiments of the apparatus of the present application are described below, which may be used to implement the communication method of the multicast broadcast service in the above embodiments of the present application. For details that are not disclosed in the embodiments of the apparatus of the present application, please refer to the embodiments of the communication method for multicast broadcast service described above in the present application.

Fig. 24 is a block diagram illustrating a communication apparatus for a multicast broadcast service according to an embodiment of the present application, which may be disposed within an I-SMF.

Referring to fig. 24, a communication apparatus 2400 for multicast broadcast service according to an embodiment of the present application includes: a first receiving unit 2402, a selecting unit 2404, a first interacting unit 2406, a second interacting unit 2408 and a third interacting unit 2410.

A first receiving unit 2402 is configured to receive a first MBS session start request sent by an i-th level control plane node in an MBS session transmission tree, where the first MBS session start request includes information of a sub-control plane node provided by the i-th level control plane node, identification information of the i-th level user plane node selected by the i-th level control plane node, a first MBS IP multicast transmission address allocated by the i-th level user plane node, and a first C-TEID used for transmitting MBS service data in a multicast manner; the selecting unit 2404 is configured to select, according to the information of the ith-level control plane node and the information of the sub-control plane node provided by the ith-level control plane node, a first user plane node capable of establishing a connection with the ith-level user plane node, and a second user plane node capable of establishing a connection with both the first user plane node and a user plane functional entity managed by the sub-control plane node; a first interaction unit 2406 is configured to send a first user plane MBS session establishment request to the first user plane node, and receive a first user plane MBS session establishment response fed back by the first user plane node, where the first user plane MBS session establishment request includes the first MBS IP multicast transport address and a first C-TEID, and the first MBS IP multicast transport address is used to enable the first user plane node to join a multicast transport group corresponding to the first MBS IP multicast transport address to receive MBS service data sent by the i-th level user plane node in a multicast manner; a second interaction unit 2408 is configured to send a second user plane MBS session establishment request to the second user plane node, and receive a second user plane MBS session establishment response fed back by the second user plane node, where the second user plane MBS session establishment request includes a second MBS IP multicast transmission address and a second C-TEID allocated by the first user plane node, and the second MBS IP multicast transmission address is used to enable the second user plane node to join a multicast transmission group corresponding to the second MBS IP multicast transmission address to receive MBS service data sent by the first user plane node in a multicast manner; the third interacting unit 2410 is configured to send a second MBS session start request to the sub-control plane node provided by the i-th level control plane node, so as to indicate the sub-control plane node provided by the i-th level control plane node to allocate a sub-user plane node to the second user plane node, where the second MBS session start request includes a third MBS IP multicast transmission address and a third C-TEID allocated by the second user plane node, and the third MBS IP multicast transmission address is used to enable the sub-user plane node to join a multicast transmission group corresponding to the third MBS IP multicast transmission address to receive MBS service data sent by the second user plane node in a multicast manner.

In some embodiments of the present application, based on the foregoing scheme, the first user-plane MBS session establishment request includes indication information for indicating the first user-plane node to allocate new MBS IP multicast distribution information; the first user plane MBS session establishment response comprises the second MBS IP multicast transmission address and the second C-TEID which are distributed by the first user plane node.

In some embodiments of the present application, based on the foregoing scheme, if the first user plane node does not support receiving MBS service data of the i-th user plane node in a multicast manner but in a point-to-point manner, the first user plane MBS session establishment request includes indication information requesting to allocate F-TEIDs to the first user plane node, the first user plane MBS session establishment response includes the F-TEIDs allocated to the first user plane node, and the F-TEIDs allocated to the first user plane node are used to enable the first user plane node to receive the MBS service data sent by the i-th user plane node in a point-to-point manner; or

The first user plane MBS conversation establishing response indicates that the first user plane node does not support the MBS service data of the i-level user plane node by a multicast mode but a point-to-point mode, and the MBS service data comprises the F-TEID distributed by the first user plane node.

In some embodiments of the present application, based on the foregoing scheme, if the second user plane node does not support receiving MBS service data of the first user plane node in a multicast manner but in a point-to-point manner, the second user plane MBS session establishment request includes indication information requesting to allocate F-TEIDs to the second user plane node, the second user plane MBS session establishment response includes F-TEIDs allocated to the second user plane node, and the F-TEIDs allocated to the second user plane node are used to enable the second user plane node to receive MBS service data sent by the first user plane node in a point-to-point manner; or

And the second user plane MBS session establishment response indicates that the second user plane node does not support the MBS service data sent by the first user plane node in a multicast mode but in a point-to-point mode, and the second user plane MBS session establishment response comprises the F-TEID distributed by the second user plane node.

In some embodiments of the present application, based on the foregoing solution, the first interacting unit 2406 is further configured to: after the second interaction unit 2408 receives the second user plane MBS session establishment response fed back by the second user plane node, if there is a second user plane node that does not support receiving MBS service data sent by the first user plane node in a multicast manner but in a point-to-point manner, sending a first user plane MBS session modification request to the first user plane node, where the first user plane MBS session modification request includes an F-TEID allocated to the second user plane node that does not support receiving MBS service data sent by the first user plane node in a multicast manner, so that the first user plane node transmits MBS service data to the second user plane node that does not support receiving MBS service data sent by the first user plane node in a point-to-point manner;

If a second user plane node supporting receiving of the MBS service data sent by the first user plane node in a multicast mode exists at the same time, the first user plane MBS session modification request further includes a field for starting multicast mode transmission to indicate that the first user plane node sends the MBS service data to the second user plane node in a multicast transmission mode at the same time.

In some embodiments of the present application, based on the foregoing solution, the third interaction unit 2410 is further configured to: after sending a second MBS session starting request to a sub control surface node provided by the ith level control surface node, receiving a second MBS session starting response fed back by the sub control surface node aiming at the second MBS session starting request, wherein the second MBS session starting response comprises first indication information;

the first indication information includes identification information of the second user plane node, first F-TEID list information and first field information used for indicating that multicast mode transmission is started, where the first field information indicates that there is a sub-user plane node supporting MBS service data sent by the second user plane node in sub-user plane nodes allocated by the sub-control plane node for the second user plane node, and the first F-TEID list information includes F-TEIDs of sub-user plane nodes that do not support MBS service data sent by the second user plane node in a multicast mode but support MBS service data sent by the second user plane node in a point-to-point mode; or

The first indication information includes identification information of the second user plane node, and does not include the first F-TEID list information and the first field information, and the first indication information is used to indicate that the sub-user plane nodes allocated by the sub-control plane node to the second user plane node all support receiving MBS service data sent by the second user plane node in a multicast manner; or

The first indication information includes identification information of the second user plane node, the first F-TEID list information, and does not include the first field information, and the first indication information is used to indicate that none of the sub-user plane nodes allocated by the sub-control plane node to the second user plane node support receiving MBS service data sent by the second user plane node in a multicast manner but in a point-to-point manner; or alternatively

The first indication information includes identification information of the second user plane node and field information for disabling multicast transmission, and does not include the first F-TEID list information, and the first indication information is used to indicate that the child control plane node does not allocate a child user plane node to the second user plane node.

In some embodiments of the present application, based on the foregoing scheme, if at least two second user plane nodes are selected, the second MBS session start response includes a first indication information list, where the first indication information list includes the first indication information corresponding to all the second user plane nodes respectively.

In some embodiments of the present application, based on the foregoing solution, the second MBS session start response further includes a failed identification information list, where the failed identification information list is used to indicate a target second user plane node to which a sub-user plane node is not allocated.

In some embodiments of the present application, based on the foregoing solution, the second interaction unit 2408 is further configured to: and if the target second user plane node which is not allocated with the sub-user plane node is determined to exist according to the second MBS conversation starting response, sending a user plane MBS conversation deleting request to the target second user plane node.

In some embodiments of the present application, based on the foregoing solution, the second interacting unit 2408 is further configured to: receiving a user plane MBS session deletion response fed back by the target second user plane node, wherein the user plane MBS session deletion response is sent by the target second user plane node after receiving the user plane MBS session deletion request, and if the target second user plane node is added into the multicast transmission group corresponding to the second MBS IP multicast transmission address, the user plane MBS session deletion response exits the multicast transmission group corresponding to the second MBS IP multicast transmission address after receiving the user plane MBS session deletion request.

In some embodiments of the present application, based on the foregoing solution, the second interaction unit 2408 is configured to: if the ith level control plane node provides at least two sub-control plane nodes, after receiving second MBS session start responses respectively fed back by all the sub-control plane nodes of the ith level control plane node, determining whether a target second user plane node which is not allocated with the sub-user plane node exists.

In some embodiments of the present application, based on the foregoing solution, the second interacting unit 2408 is further configured to: after receiving a second MBS session start response fed back by the sub-control plane node aiming at the second MBS session start request, if the first indication information contains the first F-TEID list information, sending a second user plane MBS session modification request to the second user plane node according to the identification information of the second user plane node contained in the first indication information, so as to indicate the second user plane node to respectively transmit MBS service data to the sub-user plane nodes corresponding to each F-TEID contained in the first F-TEID list information in a point-to-point manner;

wherein, if the first indication information further includes the first field information, the second user plane MBS session modification request is further used to indicate that the second user plane node simultaneously uses a multicast transmission mode to send MBS service data to a sub-user plane node of the second user plane node;

If the first indication information does not contain the first field information, the second user plane MBS session modification request is also used for indicating that the second user plane node does not need to use a multicast transmission mode to send MBS service data to the sub user plane nodes of the second user plane node.

In some embodiments of the present application, based on the foregoing solution, the second interaction unit 2408 is configured to: and if at least two second user plane nodes are selected, sending a second user plane MBS session modification request to an intermediate user plane node needing to send the second user plane MBS session modification request according to first indication information corresponding to each second user plane node contained in the second MBS session starting response.

In some embodiments of the present application, based on the foregoing solution, the third interacting unit 2410 is further configured to: after receiving a second MBS session starting response fed back by the sub control surface node aiming at the second MBS session starting request, feeding back a first MBS session starting response aiming at the first MBS session starting request to the i-th level control surface node according to the second MBS session starting response fed back by the sub control surface node.

In some embodiments of the present application, based on the foregoing scheme, the third interaction unit 2410 is configured to: if the i-th level control surface node provides at least two sub control surface nodes, after receiving second MBS session start responses respectively fed back by all the sub control surface nodes of the i-th level control surface node, feeding back the first MBS session start response to the i-th level control surface node.

In some embodiments of the present application, based on the foregoing solution, the first MBS session start response includes second indication information;

the second indication information comprises identification information of the ith user plane node, second F-TEID list information and second field information used for indicating that multicast mode transmission is started, the second field information indicates that a first user plane node supporting receiving of MBS service data sent by the ith user plane node in a multicast mode exists, and the second F-TEID list information comprises F-TEID of the first user plane node not supporting receiving of MBS service data sent by the ith user plane node in a point-to-point mode; or

The second indication information includes the identification information of the ith-level user plane node and does not include the second F-TEID list information and the second field information, and the second indication information is used to indicate that the first user plane node supports receiving MBS service data sent by the ith-level user plane node in a multicast manner; or

The second indication information includes the identification information of the i-th user plane node, the second F-TEID list information, and does not include the second field information, and the second indication information is used to indicate that the first user plane node does not support receiving MBS service data sent by the i-th user plane node in a multicast manner but in a point-to-point manner.

In some embodiments of the present application, based on the foregoing scheme, if the ith control plane node selects at least two ith user plane nodes, the first MBS session start response includes a second indication information list, where the second indication information list includes the second indication information corresponding to all the ith user plane nodes respectively.

In some embodiments of the present application, based on the foregoing solution, the second interaction unit 2408 is configured to: under the condition that at least two first user plane nodes and at least two second user plane nodes are selected, respectively sending a second user plane MBS session establishment request to each selected second user plane node, wherein the second user plane MBS session establishment request sent to each second user plane node comprises a second MBS IP multicast transmission address and a second C-TEID which are distributed by the corresponding first user plane node; wherein, the second MBS IP multicast transmission addresses distributed by different first user plane nodes are different.

In some embodiments of the present application, based on the foregoing scheme, if the ith control plane node selects at least two ith user plane nodes, the first MBS session start request includes the identification information of each ith user plane node, and the first MBS IP multicast transmission address and the first C-TEID allocated to each ith user plane node; wherein, the first MBS IP multicast transmission addresses distributed by different i-th level user plane nodes are different.

Fig. 25 shows a block diagram of a communication device of a multicast broadcast service according to an embodiment of the present application, which may be provided in an ith-level control plane node.

Referring to fig. 25, a communication device 2500 for multicast broadcast service according to an embodiment of the present application includes: a fourth interaction unit 2502 and a fifth interaction unit 2504.

The fourth interactive unit 2502 is configured to send a second user plane MBS session establishment request to an i-th user plane node selected by an i-th control plane node, and receive a second user plane MBS session establishment response fed back by the i-th user plane node, where the i-th control plane node is any level of control plane node except for a last level of control plane node in an MBS session transmission tree; a fifth interaction unit 2504 is configured to select an intermediate session management function entity I-SMF, and send a first MBS session start request to the I-SMF, where the first MBS session start request includes information of a sub-control plane node provided by the I-th level control plane node, identification information of the I-th level user plane node, a first MBS IP multicast transmission address and a first C-TEID allocated to the I-th level user plane node; the first MBS session start request is used to trigger the I-SMF to select a first user plane node capable of establishing a connection with the I-level user plane node, and a second user plane node capable of establishing a connection with both the first user plane node and a user plane functional entity managed by the sub-control plane node, and to trigger the I-SMF to send a second MBS session start request to the sub-control plane node, where the first user plane node is used to join a multicast transmission group corresponding to the first MBS IP multicast transmission address to receive MBS service data sent by the I-level user plane node in a multicast manner, the second user plane node is used to join a multicast transmission group corresponding to a second MBS IP transmission address allocated by the first user plane node to receive MBS service data sent by the first user plane node in a multicast manner, and the second MBS session start request is used to instruct the sub-control plane node to allocate a sub-user plane node to the second user plane node, and enable the sub-user plane node to receive the MBS service data sent by the first user plane node.

In some embodiments of the present application, based on the foregoing solution, the fifth interaction unit 2504 is further configured to: after sending a first MBS session start request to the I-SMF, receiving a first MBS session start response fed back by the I-SMF for the first MBS session start request; and determining whether to send a user plane MBS session modification request to the i-level user plane node or not according to the content contained in the first MBS session starting response.

In some embodiments of the present application, based on the foregoing scheme, the fifth interaction unit 2504 is configured to: and if it is determined that the user plane functional entity managed by the ith control plane node cannot directly establish a transmission path with the user plane functional entity managed by the sub control plane node according to the information of the sub control plane node provided by the ith control plane node, selecting an SMF capable of communicating with the ith control plane node and the sub control plane node as the I-SMF.

Fig. 26 is a block diagram of a communication device for multicast broadcast service according to an embodiment of the present application, which may be disposed in the first user plane node.

Referring to fig. 26, a communication device 2600 for a multicast broadcast service according to an embodiment of the present application includes: a second receiving unit 2602, a first transmitting unit 2604 and a first processing unit 2606.

The second receiving unit 2602 is configured to receive a first user plane MBS session establishment request sent by the I-SMF, where the first user plane MBS session establishment request includes a first MBS IP multicast transmission address and a first C-TEID allocated by an I-level user plane node; a first sending unit 2604 is configured to feed back a first user plane MBS session establishment response to the I-SMF, where the first user plane MBS session establishment response includes a second MBS IP multicast transmission address and a second C-TEID allocated by the first user plane node selected by the I-SMF, and the second MBS IP multicast transmission address is used to enable the second user plane node selected by the I-SMF to join a multicast transmission group corresponding to the second MBS IP multicast transmission address to receive MBS service data transmitted by the first user plane node in a multicast manner; the first processing unit 2606 is configured to, when the first user plane node supports receiving, in a multicast manner, MBS service data sent by the i-th user plane node, join a multicast transmission group corresponding to the first MBS IP multicast transmission address to receive the MBS service data sent by the i-th user plane node in a multicast manner.

In some embodiments of the present application, based on the foregoing solution, the first processing unit 2606 is further configured to: and if the first user plane node does not support receiving the MBS service data sent by the i-level user plane node in a multicast mode but in a point-to-point mode, distributing the F-TEID for receiving the MBS service data sent by the i-level user plane node in the point-to-point mode.

In some embodiments of the present application, based on the foregoing scheme, the second receiving unit 2602 is further configured to: after the first sending unit 2604 feeds back a first user plane MBS session establishment response to the I-SMF, receiving a first user plane MBS session modification request sent by the I-SMF, where the first user plane MBS session modification request includes an F-TEID allocated to a second user plane node that does not support receiving MBS service data sent by the first user plane node in a multicast manner;

the first processing unit 2606 is further configured to: and based on the F-TEID of a second user plane node which does not support receiving the MBS service data sent by the first user plane node in a multicast mode but in a point-to-point mode, transmitting the MBS service data to the second user plane node which does not support receiving the MBS service data sent by the first user plane node in a multicast mode but in a point-to-point mode, and determining whether to simultaneously use a multicast transmission mode to send the MBS service data to other second user plane nodes according to the first user plane MBS session modification request.

In some embodiments of the present application, based on the foregoing scheme, the first sending unit 2604 is further configured to: if receiving a user plane MBS session deletion request sent by the I-SMF, sending a user plane MBS session deletion response to the I-SMF; and if the user terminal is added into the multicast transmission group corresponding to the first MBS IP multicast transmission address, the user terminal exits from the multicast transmission group corresponding to the first MBS IP multicast transmission address after receiving the user terminal MBS session deleting request.

In some embodiments of the present application, based on the foregoing scheme, the first sending unit 2604 is configured to: if receiving a plurality of user plane MBS conversation establishment requests, feeding back a user plane MBS conversation establishment request feedback user plane MBS conversation establishment response aiming at one user plane MBS conversation establishment request in the plurality of user plane MBS conversation establishment requests, and feeding back a refusal message aiming at other user plane MBS conversation establishment requests in the plurality of user plane MBS conversation establishment requests so as to indicate that the user plane node is selected; or

After feeding back a first user plane MBS session establishment response to the I-SMF, if a user plane MBS session establishment request for selecting the first user plane node as a sub user plane node of other user plane nodes is received again, feeding back a refusal message aiming at the re-received user plane MBS session establishment request to indicate that the user plane node is selected.

Fig. 27 shows a block diagram of a communication device of a multicast broadcast service according to an embodiment of the present application, which may be disposed in the second user plane node.

Referring to fig. 27, a communication device 2700 of a multicast broadcast service according to an embodiment of the present application includes: a third receiving unit 2702, a second transmitting unit 2704 and a second processing unit 2706.

The third receiving unit 2702 is configured to receive a second user plane MBS session establishment request sent by the I-SMF, where the second user plane MBS session establishment request includes a second MBS IP multicast transmission address and a second C-TEID allocated by the first user plane node selected by the I-SMF; the second sending unit 2704 is configured to feed back a second user plane MBS session establishment response to the I-SMF, where the second user plane MBS session establishment response includes a third MBS IP multicast transmission address and a third C-TEID allocated by a second user plane node selected by the I-SMF, and the third MBS IP multicast transmission address is used for a sub-user plane node of the second user plane node to join a multicast transmission group corresponding to the third MBS IP multicast transmission address to receive MBS service data transmitted by the second user plane node in a multicast manner; the second processing unit 2706 is configured to, when the second user plane node supports receiving, in a multicast manner, the MBS service data sent by the first user plane node, join the multicast transmission group corresponding to the second MBS IP multicast transmission address to receive the MBS service data sent by the first user plane node in the multicast manner.

In some embodiments of the present application, based on the foregoing solution, the second processing unit 2706 is further configured to: and if the second user plane node does not support receiving the MBS service data sent by the first user plane node in a multicast mode but in a point-to-point mode, distributing the F-TEID for receiving the MBS service data sent by the first user plane node in the point-to-point mode.

In some embodiments of the present application, based on the foregoing scheme, the third receiving unit 2702 is further configured to: after the second sending unit 2704 feeds back a second user plane MBS session establishment response to the I-SMF, receiving a second user plane MBS session modification request sent by the I-SMF, where the second user plane MBS session modification request includes first F-TEID list information, and the first F-TEID list information includes F-TEIDs of sub-user plane nodes that do not support receiving MBS service data sent by the second user plane node in a multicast manner but in a point-to-point manner;

the second processing unit 2706 is further configured to: and respectively transmitting MBS service data to the sub-user plane nodes corresponding to each F-TEID contained in the first F-TEID list information in a point-to-point mode based on the first F-TEID list information, and determining whether to simultaneously use a multicast transmission mode to transmit the MBS service data to the sub-user plane nodes of the second user plane node according to the second user plane MBS session modification request.

In some embodiments of the present application, based on the foregoing scheme, the second sending unit 2704 is further configured to: if receiving a user plane MBS session deletion request sent by the I-SMF, sending a user plane MBS session deletion response to the I-SMF; and if the user terminal is added into the multicast transmission group corresponding to the second MBS IP multicast transmission address, the user terminal exits from the multicast transmission group corresponding to the second MBS IP multicast transmission address after receiving the user terminal MBS session deleting request.

In some embodiments of the present application, based on the foregoing scheme, the second sending unit 2704 is configured to: if receiving a plurality of user plane MBS conversation establishment requests, feeding back a user plane MBS conversation establishment request feedback user plane MBS conversation establishment response aiming at one user plane MBS conversation establishment request in the plurality of user plane MBS conversation establishment requests, and feeding back a refusal message aiming at other user plane MBS conversation establishment requests in the plurality of user plane MBS conversation establishment requests so as to indicate that the user plane node is selected; or

After feeding back a second user plane MBS session establishment response to the I-SMF, if a user plane MBS session establishment request for selecting the second user plane node as a sub user plane node of other user plane nodes is received again, feeding back a refusal message aiming at the received user plane MBS session establishment request again to indicate that the user plane node is selected.

FIG. 28 illustrates a schematic structural diagram of a computer system suitable for use in implementing the electronic device of an embodiment of the present application.

It should be noted that the computer system 2800 of the electronic device shown in fig. 28 is only an example, and should not bring any limitation to the functions and the scope of use of the embodiments of the present application.

As shown in fig. 28, the computer system 2800 includes a Central Processing Unit (CPU) 2801, which can perform various appropriate actions and processes, such as executing the method described in the above-described embodiment, in accordance with a program stored in a Read-Only Memory (ROM) 2802 or a program loaded from a storage portion 2808 into a Random Access Memory (RAM) 2803. In the RAM 2803, various programs and data necessary for system operation are also stored. The CPU 2801, ROM 2802, and RAM 2803 are connected to each other via a bus 2804. An Input/Output (I/O) interface 2805 is also connected to the bus 2804.

The following components are connected to the I/O interface 2805: an input portion 2806 including a keyboard, a mouse, and the like; an output portion 2807 including a Cathode Ray Tube (CRT), a Liquid Crystal Display (LCD), and the like, a speaker, and the like; a storage portion 2808 including a hard disk and the like; and a communication section 2809 including a Network interface card such as a LAN (Local Area Network) card, a modem, or the like. The communication section 2809 performs communication processing via a network such as the internet. A drive 2810 is also connected to the I/O interface 2805 as necessary. A removable medium 2811 such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, or the like is mounted on the drive 2810 as necessary, so that a computer program read out therefrom is mounted in the storage portion 2808 as necessary.

In particular, according to embodiments of the application, the processes described above with reference to the flow diagrams may be implemented as computer software programs. For example, embodiments of the present application include a computer program product comprising a computer program embodied on a computer readable medium, the computer program comprising a computer program for performing the method illustrated by the flow chart. In such embodiments, the computer program may be downloaded and installed from a network via communication portion 2809, and/or installed from removable media 2811. When the computer program is executed by a Central Processing Unit (CPU) 2801, various functions defined in the system of the present application are executed.

It should be noted that the computer readable medium shown in the embodiments of the present application may be a computer readable signal medium or a computer readable storage medium or any combination of the two. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the foregoing. More specific examples of the computer readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a Read-Only Memory (ROM), an Erasable Programmable Read-Only Memory (EPROM), a flash Memory, an optical fiber, a portable Compact Disc Read-Only Memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this application, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. In this application, however, a computer-readable signal medium may include a propagated data signal with a computer program embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated data signal may take many forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A computer readable signal medium may be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. The computer program embodied on the computer readable medium may be transmitted using any appropriate medium, including but not limited to: wireless, wired, etc., or any suitable combination of the foregoing.

The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present application. Each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams or flowchart illustration, and combinations of blocks in the block diagrams or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

The units described in the embodiments of the present application may be implemented by software, or may be implemented by hardware, and the described units may also be disposed in a processor. Wherein the names of the elements do not in some way constitute a limitation on the elements themselves.

As another aspect, the present application also provides a computer-readable medium, which may be contained in the electronic device described in the above embodiments; or may exist separately without being assembled into the electronic device. The computer readable medium carries one or more programs which, when executed by an electronic device, cause the electronic device to implement the method described in the above embodiments.

It should be noted that although in the above detailed description several modules or units of the device for action execution are mentioned, such a division is not mandatory. Indeed, the features and functionality of two or more modules or units described above may be embodied in one module or unit, according to embodiments of the application. Conversely, the features and functions of one module or unit described above may be further divided into embodiments by a plurality of modules or units.

Through the above description of the embodiments, those skilled in the art will readily understand that the exemplary embodiments described herein may be implemented by software, or by software in combination with necessary hardware. Therefore, the technical solution according to the embodiments of the present application can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (which can be a CD-ROM, a usb disk, a removable hard disk, etc.) or on a network, and includes several instructions to enable a computing device (which can be a personal computer, a server, a touch terminal, or a network device, etc.) to execute the method according to the embodiments of the present application.

Other embodiments of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the embodiments disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the application and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains.

It will be understood that the present application is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the application is limited only by the appended claims.

Claims (38)

1. A method for communicating multicast broadcast services, the method comprising:

receiving a first MBS session starting request sent by an i-th level control surface node in a multicast broadcast service MBS session transmission tree, wherein the first MBS session starting request comprises information of a sub-control surface node provided by the i-th level control surface node, identification information of the i-th level user surface node selected by the i-th level control surface node, a first MBS IP multicast transmission address distributed by the i-th level user surface node and a first general tunnel endpoint identification C-TEID used for transmitting MBS service data in a multicast mode;

Selecting a first user plane node capable of establishing connection with the ith level user plane node and a second user plane node capable of establishing connection with both the first user plane node and a user plane functional entity managed by the sub control plane node according to the information of the ith level control plane node and the information of the sub control plane node provided by the ith level control plane node;

sending a first user plane MBS session establishment request to the first user plane node, and receiving a first user plane MBS session establishment response fed back by the first user plane node, wherein the first user plane MBS session establishment request comprises a first MBS IP multicast transmission address and a first C-TEID, and the first MBS IP multicast transmission address is used for enabling the first user plane node to join a multicast transmission group corresponding to the first MBS IP multicast transmission address to receive MBS service data sent by the i-level user plane node in a multicast mode;

sending a second user plane MBS session establishment request to the second user plane node, and receiving a second user plane MBS session establishment response fed back by the second user plane node, wherein the second user plane MBS session establishment request comprises a second MBS IP multicast transmission address and a second C-TEID which are distributed by the first user plane node, and the second MBS IP multicast transmission address is used for enabling the second user plane node to join a multicast transmission group corresponding to the second MBS IP multicast transmission address to receive MBS service data sent by the first user plane node in a multicast mode;

Sending a second MBS session starting request to a sub-control surface node provided by the ith level control surface node to indicate the sub-control surface node provided by the ith level control surface node to allocate a sub-user surface node to the second user surface node, wherein the second MBS session starting request comprises a third MBS IP multicast transmission address and a third C-TEID which are allocated by the second user surface node, and the third MBS IP multicast transmission address is used for enabling the sub-user surface node to join a multicast transmission group corresponding to the third MBS IP multicast transmission address to receive MBS service data sent by the second user surface node in a multicast mode.

2. The communication method of the multicast broadcast service according to claim 1, wherein the first user plane MBS session establishment request includes indication information for indicating the first user plane node to allocate new MBSIP multicast distribution information;

the first user plane MBS session establishment response comprises the second MBS IP multicast transmission address and the second C-TEID which are distributed by the first user plane node.

3. The communication method of the multicast broadcast service according to claim 1,

if the first user plane node does not support receiving the MBS service data of the i-level user plane node in a multicast mode but in a point-to-point mode, the first user plane MBS session establishment request comprises indication information requesting to allocate a full tunnel endpoint identifier F-TEID to the first user plane node, the first user plane MBS session establishment response comprises the F-TEID allocated to the first user plane node, and the F-TEID allocated to the first user plane node is used for enabling the first user plane node to receive the MBS service data sent by the i-level user plane node in a point-to-point mode; or

The first user plane MBS conversation establishing response indicates that the first user plane node does not support the MBS service data of the i-level user plane node by a multicast mode but a point-to-point mode, and the MBS service data comprises the F-TEID distributed by the first user plane node.

4. The communication method of the multicast broadcast service according to claim 1,

if the second user plane node does not support receiving the MBS service data of the first user plane node in a multicast mode but in a point-to-point mode, the second user plane MBS session establishment request comprises indication information requesting to allocate F-TEID for the second user plane node, the second user plane MBS session establishment response comprises the F-TEID allocated by the second user plane node, and the F-TEID allocated by the second user plane node is used for enabling the second user plane node to receive the MBS service data sent by the first user plane node in a point-to-point mode; or

And the second user plane MBS session establishment response indicates that the second user plane node does not support the MBS service data sent by the first user plane node in a multicast mode but in a point-to-point mode, and the second user plane MBS session establishment response comprises the F-TEID distributed by the second user plane node.

5. The communication method of the multicast broadcast service according to claim 4, wherein after receiving the second user plane MBS session establishment response fed back by the second user plane node, the communication method of the multicast broadcast service further comprises:

if a second user plane node does not support receiving MBS service data sent by the first user plane node in a multicast mode but in a point-to-point mode, sending a first user plane MBS session modification request to the first user plane node, wherein the first user plane MBS session modification request comprises F-TEID distributed by the second user plane node which does not support receiving the MBS service data sent by the first user plane node in the multicast mode, so that the first user plane node transmits the MBS service data to the second user plane node which does not support receiving the MBS service data sent by the first user plane node in the multicast mode in the point-to-point mode;

if a second user plane node supporting receiving of the MBS service data sent by the first user plane node in a multicast mode exists at the same time, the first user plane MBS session modification request further includes a field for starting multicast mode transmission to indicate that the first user plane node sends the MBS service data to the second user plane node in a multicast transmission mode at the same time.

6. The communication method of multicast broadcast service according to claim 1, wherein after sending the second MBS session start request to the child control plane node provided by the ith control plane node, the communication method of multicast broadcast service further comprises: receiving a second MBS session starting response fed back by the sub control surface node aiming at the second MBS session starting request, wherein the second MBS session starting response comprises first indication information;

the first indication information includes identification information of the second user plane node, first F-TEID list information and first field information for indicating that multicast mode transmission is started, where the first field information indicates that there is a sub-user plane node supporting receiving, in the sub-user plane nodes allocated by the sub-control plane node to the second user plane node, MBS service data sent by the second user plane node in a multicast mode, and the first F-TEID list information includes F-TEIDs of sub-user plane nodes that do not support receiving, in a multicast mode, MBS service data sent by the second user plane node in a point-to-point mode; or

The first indication information includes identification information of the second user plane node, and does not include the first F-TEID list information and the first field information, and the first indication information is used to indicate that the sub-user plane nodes allocated by the sub-control plane node to the second user plane node all support receiving MBS service data sent by the second user plane node in a multicast manner; or

The first indication information includes identification information of the second user plane node, the first F-TEID list information, and does not include the first field information, and the first indication information is used to indicate that none of the sub-user plane nodes allocated by the sub-control plane node to the second user plane node support receiving MBS service data sent by the second user plane node in a multicast manner but in a point-to-point manner; or alternatively

The first indication information includes identification information of the second user plane node and field information for disabling multicast transmission, and does not include the first F-TEID list information, and the first indication information is used to indicate that the child control plane node does not assign a child user plane node to the second user plane node.

7. The communication method of multicast broadcast service according to claim 6, wherein if at least two second user plane nodes are selected, the second MBS session start response includes a first indication information list, and the first indication information list includes the first indication information corresponding to all the second user plane nodes respectively.

8. The communication method of multicast broadcast service according to claim 7, wherein the second MBS session start response further comprises a failed identification information list, and the failed identification information list is used to indicate a target second user plane node to which no sub-user plane node is allocated.

9. The method for communicating multicast broadcast service according to any one of claims 6 to 8, further comprising: and if the target second user plane node which is not distributed with the sub user plane node is determined to exist according to the second MBS conversation starting response, sending a user plane MBS conversation deleting request to the target second user plane node.

10. The method for communicating multicast broadcast service according to claim 9, wherein the method for communicating multicast broadcast service further comprises:

receiving a user plane MBS session deletion response fed back by the target second user plane node, wherein the user plane MBS session deletion response is sent by the target second user plane node after receiving the user plane MBS session deletion request, and if the target second user plane node is added into the multicast transmission group corresponding to the second MBS IP multicast transmission address, the user plane MBS session deletion response exits the multicast transmission group corresponding to the second MBS IP multicast transmission address after receiving the user plane MBS session deletion request.

11. The method of claim 9, wherein if the i-th level control plane node provides at least two sub-control plane nodes, the method further comprises:

And after receiving second MBS session starting responses respectively fed back by all the sub-control surface nodes of the ith-level control surface node, determining whether a target second user surface node which is not allocated with the sub-user surface node exists.

12. The communication method of multicast broadcast service according to claim 6, wherein after receiving the second MBS session start response fed back by the sub-control plane node for the second MBS session start request, the communication method of multicast broadcast service further comprises:

if the first indication information contains the first F-TEID list information, sending a second user plane MBS session modification request to a second user plane node according to the identification information of the second user plane node contained in the first indication information so as to indicate the second user plane node to respectively transmit MBS service data to sub-user plane nodes corresponding to each F-TEID contained in the first F-TEID list information in a point-to-point manner;

wherein, if the first indication information further includes the first field information, the second user plane MBS session modification request is further used to indicate that the second user plane node simultaneously uses a multicast transmission mode to send MBS service data to a sub-user plane node of the second user plane node;

If the first indication information does not contain the first field information, the second user plane MBS session modification request is also used for indicating that the second user plane node does not need to use a multicast transmission mode to send MBS service data to the sub user plane node of the second user plane node.

13. The method for communicating multicast broadcast service according to claim 12, further comprising:

and if at least two second user plane nodes are selected, sending the second user plane MBS session modification request to an intermediate user plane node needing to send the second user plane MBS session modification request according to the first indication information corresponding to each second user plane node contained in the second MBS session starting response.

14. The communication method of multicast broadcast service according to claim 6, wherein after receiving the second MBS session start response fed back by the sub-control plane node for the second MBS session start request, the communication method of multicast broadcast service further comprises:

and feeding back a first MBS session starting response aiming at the first MBS session starting request to the ith control surface node according to the second MBS session starting response fed back by the sub control surface node.

15. The communication method of multicast broadcast service according to claim 14, wherein if the i-th level control plane node provides at least two sub-control plane nodes, after receiving the second MBS session start response fed back by all sub-control plane nodes of the i-th level control plane node, feeding back the first MBS session start response to the i-th level control plane node.

16. The communication method of multicast broadcast service according to claim 14, wherein the first MBS session start response includes second indication information;

the second indication information comprises identification information of the ith user plane node, second F-TEID list information and second field information used for indicating that multicast mode transmission is started, the second field information indicates that a first user plane node supporting receiving of MBS service data sent by the ith user plane node in a multicast mode exists, and the second F-TEID list information comprises F-TEID of the first user plane node not supporting receiving of MBS service data sent by the ith user plane node in a point-to-point mode; or

The second indication information includes the identification information of the ith-level user plane node and does not include the second F-TEID list information and the second field information, and the second indication information is used to indicate that the first user plane node supports receiving MBS service data sent by the ith-level user plane node in a multicast manner; or

The second indication information includes the identification information of the i-th user plane node, the second F-TEID list information, and does not include the second field information, and the second indication information is used to indicate that the first user plane node does not support receiving MBS service data sent by the i-th user plane node in a multicast manner but in a point-to-point manner.

17. The communication method of multicast broadcast service according to claim 16, wherein if the ith control plane node selects at least two ith user plane nodes, the first MBS session start response includes a second indication information list, and the second indication information list includes the second indication information corresponding to all the ith user plane nodes respectively.

18. The communication method of multicast broadcast service according to claim 1, wherein if at least two first user plane nodes and at least two second user plane nodes are selected, sending a second user plane MBS session establishment request to the second user plane nodes, comprises:

Respectively sending the second user plane MBS session establishment request to each selected second user plane node, wherein the second user plane MBS session establishment request sent to each second user plane node comprises a second MBS IP multicast transmission address and a second C-TEID which are distributed by the corresponding first user plane node;

wherein, the second MBS IP multicast transmission addresses distributed by different first user plane nodes are different.

19. The communication method of multicast broadcast service according to claim 1, wherein if the i-th level control plane node selects at least two i-th level user plane nodes, the first MBS session start request includes the respective identification information of each i-th level user plane node, and the first mbms session start address and the first C-TEID allocated to each i-th level user plane node;

wherein, the first MBS IP multicast transmission addresses distributed by different i-th level user plane nodes are different.

20. A method for communicating multicast broadcast services, the method comprising:

sending a second user plane MBS session establishment request to an ith user plane node selected by an ith control plane node, and receiving a second user plane MBS session establishment response fed back by the ith user plane node, wherein the ith control plane node is any level of control plane node except the last level of control plane node in an MBS session transmission tree;

Selecting an intermediate session management function entity (I-SMF), and sending a first MBS session starting request to the I-SMF, wherein the first MBS session starting request comprises information of a sub control surface node provided by the ith level control surface node, identification information of the ith level user surface node, a first MBS IP multicast transmission address and a first C-TEID distributed by the ith level user surface node;

the first MBS session start request is used to trigger the I-SMF to select a first user plane node capable of establishing a connection with the I-level user plane node, and a second user plane node capable of establishing a connection with both the first user plane node and a user plane functional entity managed by the sub-control plane node, and to trigger the I-SMF to send a second MBS session start request to the sub-control plane node, where the first user plane node is used to join a multicast transmission group corresponding to the first MBS IP multicast transmission address to receive MBS service data sent by the I-level user plane node in a multicast manner, the second user plane node is used to join a multicast transmission group corresponding to a second MBS IP transmission address allocated by the first user plane node to receive MBS service data sent by the first user plane node in a multicast manner, and the second MBS session start request is used to instruct the sub-control plane node to allocate a sub-user plane node to the second user plane node, and enable the sub-user plane node to receive the MBS service data sent by the first user plane node.

21. The method of claim 20, wherein after sending the first MBS session start request to the I-SMF, the method further comprises:

receiving a first MBS session start response fed back by the I-SMF aiming at the first MBS session start request;

and determining whether to send a user plane MBS session modification request to the i-level user plane node or not according to the content contained in the first MBS session starting response.

22. The method of claim 20, wherein selecting an intermediate session management function entity, I-SMF, comprises:

and if determining that the user plane functional entity managed by the ith control plane node cannot directly establish a transmission path with the user plane functional entity managed by the sub control plane node according to the information of the sub control plane node provided by the ith control plane node, selecting an SMF capable of communicating with the ith control plane node and the sub control plane node as the I-SMF.

23. A method for communicating multicast broadcast services, the method comprising:

receiving a first user plane MBS session establishment request sent by an I-SMF, wherein the first user plane MBS session establishment request comprises a first MBS IP multicast transmission address and a first C-TEID which are distributed by an I-level user plane node;

Feeding back a first user plane MBS session establishment response to the I-SMF, wherein the first user plane MBS session establishment response comprises a second MBS IP multicast transmission address and a second C-TEID which are distributed by a first user plane node selected by the I-SMF, and the second MBS IP multicast transmission address is used for enabling a second user plane node selected by the I-SMF to join a multicast transmission group corresponding to the second MBS IP multicast transmission address to receive MBS service data transmitted by the first user plane node in a multicast mode;

if the first user plane node supports receiving the MBS service data sent by the i-th level user plane node in a multicast mode, the first user plane node is added into a multicast transmission group corresponding to the first MBS IP multicast transmission address to receive the MBS service data sent by the i-th level user plane node in a multicast mode.

24. The method for communicating multicast broadcast service according to claim 23, further comprising:

and if the first user plane node does not support the MBS service data sent by the i-level user plane node in a multicast mode but supports the point-to-point receiving mode, distributing the F-TEID for receiving the MBS service data sent by the i-level user plane node in the point-to-point mode.

25. The method of claim 23, wherein after feeding back a first user-plane MBS session establishment response to the I-SMF, the method further comprises:

receiving a first user plane MBS session modification request sent by the I-SMF, wherein the first user plane MBS session modification request comprises F-TEID distributed by a second user plane section which does not support receiving MBS service data sent by the first user plane node in a multicast mode;

and based on the F-TEID of a second user plane node which does not support receiving the MBS service data sent by the first user plane node in a multicast mode but in a point-to-point mode, transmitting the MBS service data to the second user plane node which does not support receiving the MBS service data sent by the first user plane node in a multicast mode but in a point-to-point mode, and determining whether to simultaneously use a multicast transmission mode to send the MBS service data to other second user plane nodes according to the first user plane MBS session modification request.

26. The communication method of the multicast broadcast service according to claim 23, wherein the communication method of the multicast broadcast service further comprises:

If a user plane MBS session deleting request sent by the I-SMF is received, sending a user plane MBS session deleting response to the I-SMF;

and if the user terminal is added into the multicast transmission group corresponding to the first MBS IP multicast transmission address, the user terminal exits from the multicast transmission group corresponding to the first MBS IP multicast transmission address after receiving the user terminal MBS session deleting request.

27. The communication method of the multicast broadcast service according to claim 23,

if receiving a plurality of user plane MBS conversation establishment requests, feeding back a user plane MBS conversation establishment request feedback user plane MBS conversation establishment response aiming at one user plane MBS conversation establishment request in the plurality of user plane MBS conversation establishment requests, and feeding back a refusal message aiming at other user plane MBS conversation establishment requests in the plurality of user plane MBS conversation establishment requests so as to indicate that the user plane node is selected; or

After feeding back a first user plane MBS session establishment response to the I-SMF, if a user plane MBS session establishment request for selecting the first user plane node as a sub user plane node of other user plane nodes is received again, feeding back a refusal message aiming at the received user plane MBS session establishment request again to indicate that the user plane node is selected.

28. A method for communicating multicast broadcast services, the method comprising:

receiving a second user plane MBS session establishment request sent by the I-SMF, wherein the second user plane MBS session establishment request comprises a second MBS IP multicast transmission address and a second C-TEID which are distributed by a first user plane node selected by the I-SMF;

feeding back a second user plane MBS session establishment response to the I-SMF, wherein the second user plane MBS session establishment response comprises a third MBS IP multicast transmission address and a third C-TEID which are distributed by a second user plane node selected by the I-SMF, and the third MBS IP multicast transmission address is used for a sub-user plane node of the second user plane node to join a multicast transmission group corresponding to the third MBS IP multicast transmission address to receive MBS service data transmitted by the second user plane node in a multicast mode;

and if the second user plane node supports receiving the MBS service data sent by the first user plane node in a multicast mode, adding a multicast transmission group corresponding to the second MBS IP multicast transmission address to receive the MBS service data sent by the first user plane node in the multicast mode.

29. The method for communicating multicast broadcast service according to claim 28, further comprising:

And if the second user plane node does not support receiving the MBS service data sent by the first user plane node in a multicast mode but in a point-to-point mode, distributing the F-TEID for receiving the MBS service data sent by the first user plane node in the point-to-point mode.

30. The method of claim 28, wherein after feeding back a second user-plane MBS session establishment response to the I-SMF, the method further comprises:

receiving a second user plane MBS session modification request sent by the I-SMF, wherein the second user plane MBS session modification request comprises first F-TEID list information which comprises F-TEID of a sub-user plane node which does not support receiving MBS service data sent by the second user plane node in a multicast mode but in a point-to-point mode;

and respectively transmitting MBS service data to the sub-user plane nodes corresponding to each F-TEID contained in the first F-TEID list information in a point-to-point mode based on the first F-TEID list information, and determining whether to simultaneously use a multicast transmission mode to transmit the MBS service data to the sub-user plane nodes of the second user plane node according to the second user plane MBS session modification request.

31. The method for communicating multicast broadcast service according to claim 28, wherein the method for communicating multicast broadcast service further comprises:

if receiving a user plane MBS session deletion request sent by the I-SMF, sending a user plane MBS session deletion response to the I-SMF;

and if the user terminal is added into the multicast transmission group corresponding to the second MBS IP multicast transmission address, the user terminal exits from the multicast transmission group corresponding to the second MBS IP multicast transmission address after receiving the user terminal MBS session deleting request.

32. The multicast broadcast service communication method according to claim 28,

if receiving a plurality of user plane MBS conversation establishment requests, feeding back a user plane MBS conversation establishment request feedback user plane MBS conversation establishment response aiming at one user plane MBS conversation establishment request in the plurality of user plane MBS conversation establishment requests, and feeding back a refusal message aiming at other user plane MBS conversation establishment requests in the plurality of user plane MBS conversation establishment requests so as to indicate that the user plane node is selected; or

After feeding back a second user plane MBS session establishment response to the I-SMF, if a user plane MBS session establishment request for selecting the second user plane node as a sub user plane node of other user plane nodes is received again, feeding back a refusal message aiming at the received user plane MBS session establishment request again to indicate that the user plane node is selected.

33. A communications apparatus for multicast broadcast services, comprising:

a first receiving unit, configured to receive a first MBS session start request sent by an i-th level control plane node in an MBS session transmission tree, where the first MBS session start request includes information of a sub-control plane node provided by the i-th level control plane node, identification information of an i-th level user plane node selected by the i-th level control plane node, a first MBS IP multicast transmission address allocated by the i-th level user plane node, and a first C-TEID used for transmitting MBS service data in a multicast manner;

a selecting unit, configured to select, according to the information of the ith-level control plane node and the information of the sub-control plane node provided by the ith-level control plane node, a first user plane node capable of establishing a connection with the ith-level user plane node, and a second user plane node capable of establishing a connection with both the first user plane node and a user plane functional entity managed by the sub-control plane node;

a first interaction unit, configured to send a first user plane MBS session establishment request to the first user plane node, and receive a first user plane MBS session establishment response fed back by the first user plane node, where the first user plane MBS session establishment request includes the first MBS IP multicast transport address and a first C-TEID, and the first MBS IP multicast transport address is used to enable the first user plane node to join a multicast transport group corresponding to the first MBS IP multicast transport address to receive MBS service data sent by the i-th level user plane node in a multicast manner;

A second interaction unit, configured to send a second user plane MBS session establishment request to the second user plane node, and receive a second user plane MBS session establishment response fed back by the second user plane node, where the second user plane MBS session establishment request includes a second MBS IP multicast transmission address and a second C-TEID allocated by the first user plane node, and the second MBS IP multicast transmission address is used to enable the second user plane node to join a multicast transmission group corresponding to the second MBS IP multicast transmission address to receive MBS service data sent by the first user plane node in a multicast manner;

a third interaction unit, configured to send a second MBS session start request to the sub-control plane node provided by the ith-level control plane node, so as to indicate the sub-control plane node provided by the ith-level control plane node to allocate a sub-user plane node to the second user plane node, where the second MBS session start request includes a third MBS IP multicast transport address and a third C-TEID allocated by the second user plane node, and the third MBS IP multicast transport address is used to enable the sub-user plane node to join a multicast transport group corresponding to the third MBS IP multicast transport address to receive MBS service data sent by the second user plane node in a multicast manner.

34. A communications apparatus for multicast broadcast services, comprising:

a fourth interaction unit, configured to send a second user plane MBS session establishment request to an i-th level user plane node selected by an i-th level control plane node, and receive a second user plane MBS session establishment response fed back by the i-th level user plane node, where the i-th level control plane node is any level of control plane node except for a last level of control plane node in an MBS session transmission tree;

a fifth interaction unit, configured to select an intermediate session management function entity I-SMF, and send a first MBS session start request to the I-SMF, where the first MBS session start request includes information of a sub-control plane node provided by the I-th level control plane node, identification information of the I-th level user plane node, a first MBS IP multicast transport address and a first C-TEID allocated by the I-th level user plane node;

the first MBS session start request is used to trigger the I-SMF to select a first user plane node capable of establishing a connection with the I-level user plane node, and a second user plane node capable of establishing a connection with both the first user plane node and a user plane functional entity managed by the sub-control plane node, and to trigger the I-SMF to send a second MBS session start request to the sub-control plane node, where the first user plane node is used to join a multicast transmission group corresponding to the first MBS IP multicast transmission address to receive MBS service data sent by the I-level user plane node in a multicast manner, the second user plane node is used to join a multicast transmission group corresponding to a second MBS IP transmission address allocated by the first user plane node to receive MBS service data sent by the first user plane node in a multicast manner, and the second MBS session start request is used to instruct the sub-control plane node to allocate a sub-user plane node to the second user plane node, and enable the sub-user plane node to receive the MBS service data sent by the first user plane node.

35. A communications apparatus for multicast broadcast services, comprising:

the second receiving unit is configured to receive a first user plane MBS session establishment request sent by the I-SMF, wherein the first user plane MBS session establishment request comprises a first MBS IP multicast transmission address and a first C-TEID which are distributed by an I-level user plane node;

a first sending unit, configured to feed back a first user plane MBS session establishment response to the I-SMF, where the first user plane MBS session establishment response includes a second MBS IP multicast transmission address and a second C-TEID allocated by a first user plane node selected by the I-SMF, and the second MBS IP multicast transmission address is used to enable a second user plane node selected by the I-SMF to join a multicast transmission group corresponding to the second MBS IP multicast transmission address to receive MBS service data transmitted by the first user plane node in a multicast manner;

and the first processing unit is configured to join a multicast transmission group corresponding to the first MBS IP multicast transmission address to receive the MBS service data sent by the ith user plane node in a multicast mode under the condition that the first user plane node supports receiving the MBS service data sent by the ith user plane node in a multicast mode.

36. A communications apparatus for multicast broadcast services, comprising:

a third receiving unit, configured to receive a second user plane MBS session establishment request sent by an I-SMF, where the second user plane MBS session establishment request includes a second MBS IP multicast transmission address and a second C-TEID allocated by a first user plane node selected by the I-SMF;

a second sending unit, configured to feed back a second user plane MBS session establishment response to the I-SMF, where the second user plane MBS session establishment response includes a third MBS IP multicast transport address and a third C-TEID allocated by a second user plane node selected by the I-SMF, and the third MBS IP multicast transport address is used for a sub-user plane node of the second user plane node to join a multicast transport group corresponding to the third MBS IP multicast transport address to receive MBS service data transmitted by the second user plane node in a multicast manner;

and the second processing unit is configured to join the multicast transmission group corresponding to the second MBS IP multicast transmission address to receive the MBS service data sent by the first user plane node in a multicast manner if the second user plane node supports receiving the MBS service data sent by the first user plane node in a multicast manner.

37. A computer readable medium having stored thereon a computer program, wherein the computer program, when executed by a processor, implements a communication method for a multicast broadcast service according to any one of claims 1 to 19, or implements a communication method for a multicast broadcast service according to any one of claims 20 to 22, or implements a communication method for a multicast broadcast service according to any one of claims 23 to 27, or implements a communication method for a multicast broadcast service according to any one of claims 28 to 32.

38. An electronic device, comprising:

one or more processors;

storage means for storing one or more programs which, when executed by the one or more processors, cause the one or more processors to implement a method of communicating a multicast broadcast service according to any one of claims 1 to 19, or a method of communicating a multicast broadcast service according to any one of claims 20 to 22, or a method of communicating a multicast broadcast service according to any one of claims 23 to 27, or a method of communicating a multicast broadcast service according to any one of claims 28 to 32.

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