CN118200994A

CN118200994A - Mobile switching method, device and core network element

Info

Publication number: CN118200994A
Application number: CN202211603452.XA
Authority: CN
Inventors: 宋雅琴; 武丽平
Original assignee: Datang Mobile Communications Equipment Co Ltd
Current assignee: Datang Mobile Communications Equipment Co Ltd
Priority date: 2022-12-13
Filing date: 2022-12-13
Publication date: 2024-06-14
Also published as: WO2024124990A1

Abstract

The invention provides a mobile switching method, a mobile switching device and a core network element, and relates to the technical field of communication. The method comprises the following steps: in the mobile switching process of the terminal, a core network element executes user plane function node selection according to the session of the session and the SSC mode of service continuity; and the core network element executes a corresponding switching process aiming at the selected user plane function node. The invention can solve the problems of more signaling overhead and time delay increase in the mobile switching process and the session management process of the SSC mode aiming at the mobile switching of the UE at present.

Description

Mobile switching method, device and core network element

Technical Field

The present invention relates to the field of communications technologies, and in particular, to a mobile handover method, a mobile handover device, and a core network element.

Background

Currently, in a 5G system, for mobile handover of a User Equipment (UE), a handover procedure is generally performed while an existing session anchor point is kept unchanged, for example, an Xn handover or an N2 handover is performed, and in the handover procedure, user plane information needs to be modified and information exchange is involved. After the handover procedure is performed, if there is a better user plane path or other situations, a corresponding Session management procedure may be performed according to Session AND SERVICE Continuity (SSC) mode, in which a better user plane path needs to be re-established, which may cause modification of user plane information completed in the handover procedure and release of information exchange, thereby possibly causing more signaling overhead in the Session management procedure of the mobile handover procedure and the SSC mode and increasing delay.

Disclosure of Invention

The invention provides a mobile switching method, a mobile switching device and a core network element, which can solve the problems that more signaling overhead is generated and time delay is increased in a mobile switching process and a session management process of an SSC mode aiming at UE mobile switching at present.

The embodiment of the invention provides a mobile switching method, which comprises the following steps:

In the mobile switching process of the terminal, a core network element executes user plane function node selection according to SSC mode of the session;

and the core network element executes a corresponding switching process aiming at the selected user plane function node.

Optionally, the core network element performs user plane function node selection according to a session of the session and a service continuity SSC mode, including:

In the case that the SSC mode is SSC mode 1, the core network element determines an intermediate user plane function node without changing a protocol data unit (Protocol Data Unit, PDU) session anchor;

and/or the number of the groups of groups,

And in the case that the SSC mode is SSC mode 2 or SSC mode 3, the core network element determines a target PDU session anchor point and an intermediate user plane function node.

Optionally, the target PDU session anchor includes one of:

a terminal moves a first PDU session anchor point before switching;

a second PDU session anchor identical to a first data network access identity (DN ACCESS IDENTIFIER, DNAI) of a data network to which the first PDU session anchor is to be accessed;

A second PDU session anchor point which is the same as the first DNAI of the data network accessed by the first PDU session anchor point and has association relation with the target access network node to which the terminal is mobile switched;

The accessed data network is a second PDU session anchor point of a second DNAI; wherein the second DNAI corresponds to the same data network name (Data Network Name, DNN) and/or single network slice selection assistance information (Single Network Slice Selection Assistance Information, S-NSSAI) as the first DNAI.

Optionally, in the case of changing the PDU session anchor point when performing user plane function node selection, the core network element performs a corresponding handover procedure for the selected user plane function node, including:

Under the condition that the changed second PDU session anchor point is the same as DNAI of the data network accessed by the first PDU session anchor point before mobile switching of the terminal, the core network element executes a session management process related to the second PDU session anchor point;

and/or the number of the groups of groups,

And under the condition that the changed second PDU session anchor point is different from DNAI of the data network accessed by the first PDU session anchor point before the mobile switching of the terminal, the core network element executes the session management process of the SSC mode 2 or the SSC mode 3.

Optionally, the core network element performs a session management procedure related to the second PDU session anchor, including:

The core network element establishes an N4 session with the second PDU session anchor point, and constructs a user plane path between a target access network node switched by the terminal and the second PDU session anchor point through message interaction;

And the core network element releases a user plane path between a source access network node and the first PDU session anchor point.

Optionally, before the core network element releases the user plane path between the source access network node and the first PDU session anchor point, the method further includes:

The core network element modifies an N4 session with the first PDU session anchor point and/or the second PDU session anchor point, and constructs an indirect forwarding path of the first PDU session anchor point and the second PDU session anchor point through message interaction;

And under the condition that the forwarding of the cached downlink data packet through the indirect forwarding path is completed, the core network element releases the indirect forwarding path.

Optionally, the core network element establishes an N4 session with the second PDU session anchor, and constructs a user plane path between the target access network node to which the terminal is switched and the second PDU session anchor through message interaction, including:

the core network element obtains user plane information of the second PDU session anchor point in the process of establishing the N4 session with the second PDU session anchor point;

after the core network element establishes an N4 session with the second PDU session anchor point, the core network element sends the user plane information of the second PDU session anchor point to the target access network node, and sends the user plane information of the target access network node to the second PDU session anchor point.

Optionally, the sending the user plane information of the target access network node to the second PDU session anchor point includes:

And in the process that the core network element releases the indirect forwarding path of the first PDU session anchor point and the second PDU session anchor point, transmitting the user plane information of the target access network node to the second PDU session anchor point.

Optionally, the core network element performs a session management procedure of SSC mode 2 or SSC mode 3, including:

when the SSC mode is SSC mode 2, the core network element executes the session management process of SSC mode 2 with PDU session anchor point changed;

and/or the number of the groups of groups,

And when the SSC mode is SSC mode 3, the core network element executes the session management process of the SSC mode 3 with the PDU session anchor point changed.

The embodiment of the invention provides a mobile switching device, which comprises a memory, a transceiver and a processor;

Wherein the memory is used for storing a computer program; the transceiver is used for receiving and transmitting data under the control of the processor; the processor is configured to read the computer program in the memory and perform the following operations:

In the mobile switching process of the terminal, user plane function node selection is executed according to SSC mode of the session;

And executing corresponding switching process aiming at the selected user plane function node.

Optionally, the processor is configured to read the computer program in the memory and perform the following operations:

under the condition that the SSC mode is SSC mode 1, determining an intermediate user plane function node under the condition that a PDU session anchor point is not changed;

and/or the number of the groups of groups,

And under the condition that the SSC mode is SSC mode 2 or SSC mode 3, determining a target PDU session anchor point and an intermediate user plane function node.

Optionally, the target PDU session anchor includes one of:

a terminal moves a first PDU session anchor point before switching;

a second PDU session anchor identical to the first DNAI of the data network to which the first PDU session anchor is attached;

The accessed data network is a second PDU session anchor point of a second DNAI; wherein the second DNAI corresponds to the same DNN and/or S-NSSAI as the first DNAI.

Optionally, in case of changing PDU session anchor when performing user plane function node selection, the processor is configured to read the computer program in the memory and perform the following operations:

executing a session management process related to a second PDU session anchor point under the condition that the changed second PDU session anchor point is the same as DNAI of a data network accessed by the first PDU session anchor point before mobile switching of the terminal;

and/or the number of the groups of groups,

In case that the changed second PDU session anchor is different from DNAI of the data network to which the first PDU session anchor before mobile handover of the terminal is accessed, performing a session management procedure of SSC mode 2 or SSC mode 3.

establishing an N4 session with the second PDU session anchor point, and constructing a user plane path between a target access network node switched by a terminal and the second PDU session anchor point through message interaction;

And releasing the user plane path between the source access network node and the first PDU session anchor point.

Optionally, the computer program for reading in the memory further performs the following operations:

Modifying an N4 session with the first PDU session anchor point and/or the second PDU session anchor point, and constructing an indirect forwarding path of the first PDU session anchor point and the second PDU session anchor point through message interaction;

And releasing the indirect forwarding path under the condition that the forwarding of the cached downlink data packet through the indirect forwarding path is completed.

In the process of establishing an N4 session with the second PDU session anchor point, obtaining user plane information of the second PDU session anchor point;

After establishing an N4 session with the second PDU session anchor point, transmitting user plane information of the second PDU session anchor point to the target access network node, and transmitting user plane information of the target access network node to the second PDU session anchor point.

And in the process of releasing the indirect forwarding paths of the first PDU session anchor point and the second PDU session anchor point, transmitting the user plane information of the target access network node to the second PDU session anchor point.

When the SSC mode is SSC mode 2, executing a session management process of SSC mode 2 with PDU session anchor point changed;

and/or the number of the groups of groups,

And when the SSC mode is SSC mode 3, executing the session management process of the SSC mode 3 with the PDU session anchor point changed.

The embodiment of the invention also provides a core network element, which comprises:

The first processing unit is used for executing user plane function node selection according to SSC mode of session in the mobile switching process of the terminal;

and the second processing unit is used for executing corresponding switching process aiming at the selected user plane function node.

The embodiment of the invention also provides a processor-readable storage medium storing a computer program for causing the processor to execute the steps of the mobile switching method.

The technical scheme of the invention has the beneficial effects that:

In the embodiment of the invention, in the mobile switching process of the terminal, the core network element executes the user plane function node selection according to the SSC mode of the session, namely, the SSC mode of the session can be considered in the mobile switching process, the PDU session anchor point can be selected to be changed or the better user plane path can be selected under the condition of not changing the PDU session anchor point, and the user plane function node selection is not only executed under the condition of not changing the PDU session anchor point, so that the core network element executes the corresponding switching process aiming at the selected user plane function node, thereby reducing signaling expenditure generated by repeatedly updating the user path in the session management process of the mobile switching process and the SSC mode, and being beneficial to reducing time delay.

Drawings

FIG. 1 shows one of the schematic diagrams of an Xn handoff procedure with an intermediate user plane function node inserted;

FIG. 2 is a second schematic diagram of an Xn handoff procedure with an intermediate user plane function node inserted;

FIG. 3 is a diagram showing the N2 handover preparation phase in the 5G system domain;

FIG. 4 is a diagram illustrating an N2 handover execution phase in the 5G system domain;

fig. 5 shows a schematic diagram of an SSC mode 2 change PDU session anchor;

FIG. 6 shows a schematic diagram of SSC mode 3 changing PDU session anchor;

FIG. 7 is a flow chart of a mobile switching method according to an embodiment of the invention;

FIG. 8 is a schematic diagram of an Xn switching process according to an embodiment of the present invention;

FIG. 9 is a second schematic diagram of an Xn switching process according to an embodiment of the present invention;

fig. 10 is a schematic diagram of an N2 handover preparation phase according to an embodiment of the present invention;

FIG. 11 is a schematic diagram of an N2 handover execution phase according to an embodiment of the present invention;

Fig. 12 is a schematic diagram showing an embodiment of the present invention in which the N2 switch performs SSC mode 2/mode 3 procedure;

FIG. 13 shows a block diagram of a mobile switching device according to an embodiment of the present invention;

fig. 14 shows a block diagram of a core network element of the present invention.

Detailed Description

In order to make the technical problems, technical solutions and advantages to be solved more apparent, the following detailed description will be given with reference to the accompanying drawings and specific embodiments. In the following description, specific details such as specific configurations and components are provided merely to facilitate a thorough understanding of embodiments of the invention. It will therefore be apparent to those skilled in the art that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

It should be appreciated that reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

In various embodiments of the present invention, it should be understood that the sequence numbers of the following processes do not mean the order of execution, and the order of execution of the processes should be determined by the functions and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

In addition, the terms "system" and "network" are often used interchangeably herein.

The technical scheme provided by the embodiment of the application can be suitable for various systems, in particular to a 5G system. For example, applicable systems may be global system for mobile communications (global system of mobile communication, GSM), code division multiple access (code division multiple access, CDMA), wideband code division multiple access (Wideband Code Division Multiple Access, WCDMA) universal packet Radio service (GENERAL PACKET Radio service, GPRS), long term evolution (long term evolution, LTE), LTE frequency division duplex (frequency division duplex, FDD), LTE time division duplex (time division duplex, TDD), long term evolution-advanced (long term evolution advanced, LTE-a), universal mobile system (universal mobile telecommunication system, UMTS), worldwide interoperability for microwave access (worldwide interoperability for microwave access, wiMAX), 5G New air interface (New Radio, NR) systems, and the like. Terminal devices and network devices are included in these various systems. Core network parts may also be included in the system, such as Evolved packet system (Evolved PACKET SYSTEM, EPS), 5G system (5 GS), etc.

Multiple-input Multiple-output (Multi Input Multi Output, MIMO) transmissions may be made between the network device and the terminal device, each using one or more antennas, and the MIMO transmissions may be Single User MIMO (SU-MIMO) or Multiple User MIMO (MU-MIMO). The MIMO transmission may be 2D-MIMO, 3D-MIMO, FD-MIMO, or massive-MIMO, or may be diversity transmission, precoding transmission, beamforming transmission, or the like, depending on the form and number of the root antenna combinations.

In the embodiment of the invention, the term "and/or" describes the association relation of the association objects, which means that three relations can exist, for example, a and/or B can be expressed as follows: a exists alone, A and B exist together, and B exists alone. The character "/" generally indicates that the context-dependent object is an "or" relationship.

The term "plurality" in embodiments of the present application means two or more, and other adjectives are similar.

The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments, but not all embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

The following is presented for 5G system switching and SSC mode:

1. 5G system handoff

UE handover includes Xn handover and N2 handover. For an Xn handover, referring to fig. 1 and 2, a schematic diagram of an Xn handover procedure is given with an intermediate user plane function node (I-UPF) inserted. For an N2 handover, a schematic diagram of an N2 handover preparation phase is given with reference to fig. 3, and a schematic diagram of an N2 handover execution handover is given in fig. 4.

2. SSC mode of 5G system (SSC mode)

During session establishment, a session management function (Session Management Function, SMF) selects the SSC mode of the session based on the SSC mode allowed in the subscription data and the SSC mode requested by the UE. After session establishment, the SSC mode is no longer changed.

(1) SSC mode 1 (SSC mode 1)

PDU session anchor (PDU Session Anchor, PSA) is unchanged, intermediate SMF (I-SMF) and I-UPF may be inserted, the traffic is continuous, but transmission delay may be high due to PSA unchanged, I-UPF inserted, etc.

(2) SSC mode 2 (SSC mode 2)

The SSC mode 2 is a break-before-make connection, there may be a short break, and a new connection may be made by selecting a more appropriate new SMF and new PSA.

As shown in fig. 5, the SMF performs the following steps to change the PSA that provides the PDU session service of SSC mode 2 to the UE, and this procedure releases the existing PDU session associated with the old PSA (i.e., UPF1 in fig. 5) and establishes a new PDU session with the new PSA (i.e., UPF2 in fig. 5) to the same Data Network (DN). The method comprises the following specific steps:

step 1: the SMF network element decides to change the user plane function (User Plane Function, UPF) node, the trigger factor being that the SMF network element thinks that it can benefit from changing the UPF node;

step 1a: the SMF network element receives a target data network access identifier (TARGET DNAI) from a session management policy control function (Session Management Policy Control Function, SM-PCF) network element;

If the UPF (PSA) is not capable of connecting to this TARGET DNAI, SMF network element, a session management context state notification request (e.g., nsmf _ PDUSession _ SMContextStatusNotify Request) will be invoked to the access and mobility management function (ACCESS AND Mobility Management Function, AMF) network element, carrying the target DNAI information (TARGET DNAI info) and indicating whether SMF reselection is required.

The AMF network element stores TARGET DNAI info and is used for SMF selection, and can control the UPF connected to the DNAI towards the same DNN and S-NSSAI at the next PDU session establishment.

Step 2: a PDU Session release (release) procedure is performed and the PDU Session release command message (PDU Session Release Command message) in the N1 Session management Information (N1 SM Information) contains a PDU Session identification (PDU Session ID) and a Cause (Cause) indicating that a PDU Session to the same DN needs to be re-established.

Step 3: when the UE receives PDU Session Release Command, the Cause indicates that the PDU session needs to be re-established for the same DN sent in step 2, the UE generates a new PDU session ID, and initiates a PDU session establishment procedure according to the prior art.

The AMF network element then selects an SMF network element, which can select a new UPF (i.e., UPF 2) for the PDU session re-established by SSC mode 2.

If the AMF network element has received TARGET DNAI info from the old SMF (i.e. SMF 1), the AMF network element selects the SMF network element and carries TARGET DNAI info in a create session management context request (e.g. Nsmf _ PDUSession _ CreateSMContext Request) sent to the SMF network element and then deletes the locally stored TARGET DNAI info. The SMF network element selects a new PDU session anchor using the target DNAI.

It should be noted that: since the SSC mode 2 releases the session first and then establishes the session newly, the context of the old session does not need to be exchanged, and only the new session context needs to be created.

(3) SSC mode 3 (SSC mode 3)

The SSC mode 3 is a connection-first-disconnection-later-disconnection type, a more proper new SMF and a new PSA can be selected when a connection is newly established, the service is continuous, the time delay is low, but the UE is required to maintain two sessions and two IP addresses of the same service in a short time;

As shown in fig. 6, the SMF network element performs the following steps to change the PSA that provides the PDU session service of SSC mode 3 to the UE. And this procedure releases the existing PDU session associated with the old PSA (i.e., UPF1 in fig. 6). Before release, the PDU session establishes a new PDU session to the same DN with a new PSA (i.e., UPF2 in fig. 6) controlled by the same SMF network element. The SMF network element may also decide to reassign a new SMF (i.e., SMF2 in fig. 6). The method comprises the following specific steps:

step 1: the SMF network element decides to change the UPF or SMF of the service.

If the "indication of application relocation possibility" attribute in Policy Control and Charging (PCC) rules indicates that once this application is selected, DNAI is not changed, the SMF determines that the SMF cannot be changed.

Step 1a: if the UPF (PSA) cannot connect to the target DNAI received by the SMF network element from the SM-PCF network element, the SMF network element will invoke a session management context state notification request (e.g., nsmf _ PDUSession _ SMContextStatusNotify Request) service operation to the AMF network element, which carries the request target DNAI information and indicates whether SMF reselection is required.

The destination DNAI information is used for SMF selection and can control the UPF connected to the DNAI towards the same DNN and S-NSSAI at the next PDU session establishment.

Step 2: the SMF network element performs N1N2message interactions with the AMF network element (e.g., namf _communication_n1n2 MESSAGETRANSFER), carrying a PDU Session ID, an SMF relocation request indication, an N1 SM container (e.g., PDU Session modification command including a Cause, a protocol configuration option (Protocol Configuration Options, PCO) (e.g., PDU Session address lifetime value etc. )(PDU Session ID,SMF Reallocation requested indication,N1 SM container(PDU Session Modification Command(Cause,PCO(PDU Session Address Lifetime value))), where PDU Session ID represents an existing PDU Session to be relocated, cause represents a need to reestablish the PDU Session to the same DN. SMF Reallocation requested indication represents whether a need to reassign the SMF. PDU Session ADDRESS LIFETIME value is required to be delivered to the UE upper layer in PCO), indicating how long the network is willing to maintain the PDU Session.

Step 3a: the AMF network element forwards the non-intervening layer (Non Access Stratum, NAS) message to the UE. The UE may provide a release timer value to an upper layer if received in the PDU session modification command.

Step 3b: the UE acknowledges the PDU session modification command.

Step 3c: the AMF forwards AN N1 session management container (PDU session modification command reply (PDU Session Modification Command ACK)) received from AN Access Network (AN) node (e.g., radio Access Network (Radio Access Network, RAN) node) to the SMF1 by updating a session management context service operation (e.g., nsmf _ PDUSession _ UpdateSMContext).

Step 3d: SMF1 replies back to the AMF network element with a corresponding update session management context response (e.g., nsmf _ PDUSession _ UpdateSMContext).

Step 4: if the UE receives a PDU session modification command, the UE may decide to initiate a PDU session establishment procedure.

According to the SSC mode, the UE generates a new PDU session ID and initiates a PDU session establishment request using the new PDU session ID. The new PDU session ID is included as a PDU session ID in the NAS request message, and the old PDU session ID indicating the existing PDU session to be released is also provided to the AMF in the NAS request message.

If a reassignment of SMFs is requested in step 2 of the present flow, the AMF selects a different SMF. Otherwise, the AMF sends a create session management context request (e.g., nsmf _ PDUSession _ CreateSMContext) to the same SMF serving the old PDU session ID.

If the target DNAI information has been received from the old SMF (i.e., SMF 1), the AMF network element uses the stored target DNAI information to select a new SMF for the same DNN and S-SSAI oriented PDU session.

The AMF network element includes the target DNAI in the Nsmf _ PDUSession _ CreateSMContext request and deletes the stored target DNAI information. If the AMF has received a session management Context identification (SM Context ID) from the old SMF, the AMF network element can carry the SM Context ID in the Nsmf _ PDUSession _ CreateSMContext request.

If the SMF is not reassigned, the AMF may carry the PDU Session ID and the old PDU Session ID in the Nsmf _ PDUSession _ CreateSMContext request. The SMF detects that the PDU Session establishment request is related to the trigger in step 2 based on the presence of the old PDU Session ID in the Nsmf _ PDUSession _ CreateSMContext request.

The SMF stores the new PDU session ID and selects a new PDU session anchor (i.e., UPF 2) for the new PDU session.

If the new SMF receives the SM Context ID in the Nsmf _ PDUSession _ CreateSMContext request, the new SMF retrieves the application function (Application Function, AF) coordination information by sending a PDU session Context request (e.g., nsmf _ PDUSession _ ContextRequest) to the old SMF, and an "AF coordination information" portion is requested that represents the 5G session management Context (5G SM Context).

If the SMF receives a target DNAI in the Nsmf _ PDUSession _ CreateSMContext request, the SMF uses the target DNAI to select a new PDU session anchor.

Based on the above, the user plane information needs to be modified and information exchange is related in the handover procedure, after the handover procedure is performed, if there is a better user plane path or other conditions, a corresponding session management procedure may be performed according to the SSC mode, in this process, the better user plane path needs to be re-established, which may result in the situation that the user plane information completed in the handover procedure is modified and the information exchange is released again, thereby possibly causing more signaling overhead in the session management procedure of the mobile handover procedure and the SSC mode and causing a larger time delay. The embodiment of the application provides a mobile switching method, a mobile switching device and a core network element, which can solve the problems of more signaling overhead and larger time delay in a mobile switching process and a session management process of an SSC mode.

The method and the device are based on the same application, and because the principles of solving the problems by the method and the device are similar, the implementation of the device and the method can be referred to each other, and the repetition is not repeated.

As shown in fig. 7, an embodiment of the present invention provides a mobile handover method, including the steps of:

Step 71: in the mobile switching process of the terminal, the core network element executes user plane function node selection according to the SSC mode of the session.

Optionally, the core network element may be an SMF network element or other network element (e.g., a newly added network element for implementing this function, etc.).

Optionally, the SSC mode of the session may be a SSC mode of the session determined by the SMF network element according to the SSC mode allowed in the subscription data and the SSC mode requested by the UE in the session establishment procedure. Optionally, after session establishment, the SSC pattern is no longer changed.

Alternatively, the user plane function node selection may be performed by selecting a determination intermediate user plane function node, or may be by updating a PDU session anchor (PDU Session Anchor, PSA), selecting a determination intermediate user plane function node, or the like.

It should be noted that, when the core network element performs the selection of the user plane function node, other factors may be considered besides the factor of the SSC mode of the session, for example, the load of the user plane function (User Plane Function, UPF) node, the available user plane function node position, and the like.

Step 72: and the core network element executes a corresponding switching process aiming at the selected user plane function node.

In this embodiment, in the mobile handover process of the terminal, the core network element performs user plane function node selection according to the SSC mode of the session, that is, in the mobile handover process, the SSC mode of the session may be considered, and a PDU session anchor point may be selectively changed or a better user plane path may be selected without being changed.

In the case that the SSC mode is SSC mode 1, the core network element determines an intermediate user plane function node without changing a protocol data unit PDU session anchor;

and/or the number of the groups of groups,

In this embodiment, in the mobile handover process of the terminal, when the core network element (such as SMF) performs user plane function node selection, a target UPF may be selected based on the SSC mode of the session, which specifically is: if the session is SSC mode 2 or SSC mode 3, then the optimal user plane path is selected if the PDU session anchor is allowed to change (i.e., if changing the PDU session anchor may benefit, then a more optimal new user plane function node may be selected as the PDU session anchor). If the session is SSC mode 1, then the PDU session anchor is maintained, and the optimal user plane path (e.g., updating the intermediate user plane function node, etc.) may be selected.

Optionally, the target PDU session anchor includes one of:

a terminal moves a first PDU session anchor point before switching;

The accessed data network is a second PDU session anchor point of a second DNAI; wherein the second DNAI corresponds to the same data network name DNN and/or single network slice selection assistance information S-NSSAI as the first DNAI.

For example: in the mobile handover process of the terminal, when the core network element (such as SMF) performs user plane function node selection, a target UPF may be selected based on the SSC mode of the session, and more specifically: if the session is SSC mode 2 or SSC mode 3, and benefits when changing PDU session anchor, then the optimal UPF node may be selected as PDU session anchor, e.g. the same UPF as the first DNAI of the data network to which the first PDU session anchor is connected is selected as new PDU session anchor (i.e. the second PDU session anchor), preferably the same UPF as the first DNAI of the data network to which the first PDU session anchor is connected and associated with the target access network node to which the terminal is mobile switched is selected as new PDU session anchor (i.e. the second PDU session anchor); if there is no UPF that is the same as the first DNAI of the data networks accessed by the first PDU session anchor, the accessed data network can be selected to be the UPF of the second DNAI of the same DNN and/or S-NSSAI corresponding to the first DNAI as a new PDU session anchor (i.e. a second PDU session anchor), etc.; otherwise, the PDU session anchor point may not be changed, i.e. the first PDU session anchor point before mobile handover of the terminal is maintained. If the session is SSC mode 1, the PDU session anchor is not changed, i.e. the first PDU session anchor before mobile handoff of the terminal is maintained.

Optionally, in the case that the PDU session anchor is not changed when the user plane function node selection is performed, for example, in the case that the session is SSC mode 1, or the session is SSC mode 2 or SSC mode 3 and the PDU session anchor before the terminal is kept for mobile handover, the core network element performs a session management procedure corresponding to the PDU session anchor before the terminal is kept for mobile handover, for example, refer to the above-mentioned procedures such as the session establishment and/or modification procedures of the 5G system handover procedure.

and/or the number of the groups of groups,

For example: in the process of terminal mobile handover, when the core network element (such as SMF) performs user plane function node selection, if the SSC mode 2 or SSC mode 3 for a session changes the PDU session anchor point to a UPF that is the same as the first DNAI of the data network to which the first PDU session anchor point is accessed as a new PDU session anchor point (i.e., a second PDU session anchor point) (a UPF that is the same as the first DNAI of the data network to which the first PDU session anchor point is accessed, or a UPF that is the same as the first DNAI of the data network to which the first PDU session anchor point is accessed and has an association relationship with a target access network node to which the terminal mobile handover is performed, etc.), the core network element performs a session management procedure (such as a session establishment and/or modification procedure, etc.) related to the second PDU session anchor point. If the SSC mode 2 or SSC mode 3 for a session changes PDU session anchor to a different UPF than the first DNAI of the data networks to which said first PDU session anchor is attached as a new PDU session anchor (i.e. a second PDU session anchor) (e.g. the attached data network is the UPF of the second DNAI of the same DNN and/or S-NSSAI as said first DNAI), the core network element performs session management procedures for the respective SSC mode 2 or SSC mode 3, such as session establishment and/or modification procedures for the SSC mode of the 5G system described above.

Specifically, as an implementation manner, the core network element establishes an N4 session with the second PDU session anchor, and constructs a user plane path between the target access network node to which the terminal is switched and the second PDU session anchor through message interaction, including:

The core network element sends user plane information of a target access network node to which a terminal is switched to the second PDU session anchor point in the process of establishing the session with the second PDU session anchor point N4, and obtains the user plane information of the second PDU session anchor point;

And after the core network element modifies the session process with the first PDU session anchor N4, the core network element sends the user plane information of the second PDU session anchor to the target access network node.

For example: the core network element sends an N4 session establishment request message to the second PDU session anchor point; the N4 session establishment request message is used for requesting allocation of user plane information, and the first N4 session establishment request message carries the user plane information of the target access network node; the core network element receives an N4 session establishment response message fed back by the second PDU session anchor point; the N4 session establishment response message carries the user plane information of the second PDU session anchor point, so that the core network element obtains the user plane information of the second PDU session anchor point and forwards the user plane information of the target access network node to which the terminal is switched to the second PDU session anchor point, that is, the second PDU session anchor point, the target access network node and the downlink of the terminal are communicated.

The core network element sends an N4 session modification request message to the first PDU session anchor point; the N4 session modification request message is used for requesting to release the relevant message matching and forwarding rules; the core network element receives an N4 session modification response message fed back by the first PDU session anchor point; the N4 session modification response message is used for confirming the matching and forwarding rule of the release related message; and the core network element sends the user plane information of the second PDU session anchor point to the target access network node, so that the core network element forwards the user plane information of the second PDU session anchor point to the target access network node to which the terminal is switched, namely, the terminal, the target access network node and the uplink of the second PDU session anchor point are communicated.

Specifically, as another implementation manner, the core network element establishes an N4 session with the second PDU session anchor, and constructs a user plane path between a target access network node to which the terminal is switched and the second PDU session anchor through message interaction, including:

For example: the core network element sends an N4 session establishment request message to the second PDU session anchor point; the N4 session establishment request message is used for requesting to distribute user plane information; the core network element receives an N4 session establishment response message fed back by the second PDU session anchor point; the N4 session establishment response message carries the user plane information of the second PDU session anchor point, so that the core network element obtains the user plane information of the second PDU session anchor point and determines to establish the N4 session of the second PDU session anchor point. And the core network element sends the user plane information of the second PDU session anchor point to the target access network node and sends the user plane information of the target access network node to the second PDU session anchor point, so that the uplink of the terminal, the target access network node and the second PDU session anchor point is communicated, and the downlink of the second PDU session anchor point, the target access network node and the terminal is communicated.

For example: the core network element sends an N4 session modification request message to the first PDU session anchor point and/or the second PDU session anchor point; the second N4 session modification request message is used for establishing an indirect forwarding path of the first PDU session anchor point and the second PDU session anchor point; the core network element receives an N4 session modification response message fed back by the first PDU session anchor point and/or the second PDU session anchor point; the N4 session modification response message is used for confirming establishment of an indirect forwarding path of the first PDU session anchor point and the second PDU session anchor point, that is, a core network element determines establishment of an indirect forwarding path of the first PDU session anchor point and the second PDU session anchor point, and the indirect forwarding path can be used for forwarding the buffered downlink data packet. And under the condition that the forwarding of the cached downlink data packet through the indirect forwarding path is completed, the core network element releases the indirect forwarding path.

And in the process that the core network element releases the indirect forwarding paths of the first PDU session anchor point and the second PDU session anchor point, the user plane information of the target access network node is sent to the second PDU session anchor point, namely, in the process that the core network element releases the indirect forwarding paths of the first PDU session anchor point and the second PDU session anchor point, the downlink of the second PDU session anchor point, the target access network node and the terminal is communicated.

That is, as a further implementation manner, the core network element establishes an N4 session with the second PDU session anchor, and constructs a user plane path between the target access network node to which the terminal is switched and the second PDU session anchor through message interaction, including:

After the core network element establishes an N4 session with the second PDU session anchor point, an indirect forwarding path between the first PDU session anchor point and the second PDU session anchor point is established, and user plane information of the second PDU session anchor point, namely uplink of a terminal, a target access network node and the second PDU session anchor point is communicated to the target access network node;

And after the cached downlink data packet is forwarded through the indirect forwarding path, the core network element releases the indirect forwarding path, and then the user plane information of the second PDU session anchor point, namely the downlink of the second PDU session anchor point, the target access network node and the terminal is opened, is sent to the target access network node.

Alternatively, the user plane information may include data network Tunnel information (CN Tunnel Info) or the like.

When the SSC mode is SSC mode 2, the core network element executes the session management process of SSC mode 2 with PDU session anchor point changed; for example: when the SSC mode is SSC mode 2, the core network element executes the session establishment and/or modification procedure of SSC mode 2 that the session anchor point of the PDU of the 5G system changes, which is not described herein again to avoid repetition.

And/or the number of the groups of groups,

When the SSC mode is SSC mode 3, the core network element executes the session management process of SSC mode 3 with PDU session anchor point changed; for example: when the SSC mode is SSC mode 3, the core network element executes the session establishment and/or modification procedure of SSC mode 3 with the changed session anchor point of the PDU in the 5G system, which is not described herein again to avoid repetition.

The mobile handover method of the present invention is described below with reference to specific embodiments:

example 1: an Xn handover accesses the same DNAI new PSA, i.e. changes PDU session anchor and the changed second PDU session anchor is the same as the first DNAI of the data network to which the first PDU session anchor is accessed. As shown in fig. 8, the method specifically comprises the following steps:

Step 80: before the handover procedure of the core network Xn, the related handover procedure has been completed between the source access network node (S-RAN) and the target access network node (T-RAN), since the T-RAN has obtained the Old PSA (Old UPF (PSA), i.e. the user plane information of the first PDU session anchor before handover (e.g. CN Tunnel Info), at this time:

the transmission path of a Downlink (DL) packet is: the over UPF (PSA), S-RAN, T-RAN, UE, S-RAN forwards DL data packet to T-RAN;

The transmission path of the Uplink (UL) packet is: UE, T-RAN, old UPF (PSA).

Step 81: the T-RAN sends an N2 path switching request to the AMF network element.

Step 82: the AMF network element sends an SM uplink update request to the SMF network element.

Step 83: the SMF network element performs UPF selection, including:

If the SSC mode of the session is SSC mode 1, the method is consistent with the 5G system switching flow.

If the SSC pattern of the session is SSC mode 2 or SSC mode 3, the SMF network element adds a factor based on the SSC pattern of the session to perform UPF selection. For example: within the service scope of the SMF network element, a New PSA (New UPF (PSA), i.e. a second PDU session anchor point) may be selected; if a better UPF (PSA) than the old UPF (PSA) can not be found, the flow is consistent with the 5G system switching flow; if a better UPF (PSA) than old UPF (PSA) is found, then step 84 is performed.

Among other things, selecting a UPF (PSA) that is better than the old UPF (PSA) includes, but is not limited to, the following rule implementation:

Determining a better UPF (PSA) based on a path distance (e.g., hop count) between base stations, N3 UPF, UPF PSA, DN, loading conditions of the UPF, etc.;

Preferably, a UPF that has access to the same DNAI as the old UPF (PSA) and that has a connection to the T-RAN is selected as the UPF (PSA) connected to the same DNAI and as the N3 UPF connected to the Target NG-RAN;

If no UPF is found that is both an N3 UPF and a UPF (PSA), the SMF selects the N3 UPF that can be connected to the T-RAN as the I-UPF and selects the UPF (PSA) that can access the same DNAI.

Steps 84a and 84b: the SMF network element establishes an N4 session with a New UPF (PSA) and requests the New UPF (PSA) to distribute corresponding user plane information (such as tunnel information), and the New UPF (PSA) feeds the corresponding user plane information (such as tunnel information) back to the SMF through a response message; meanwhile, the SMF network element transmits user plane information (e.g., AN Tunnel Info) of the T-RAN to a New UPF (PSA).

Steps 85a and 85b: the SMF network element requests Old UPF (PSA) to modify the N4 session, and releases the relevant downlink message matching and forwarding rules.

Step 86, after the old UPF (PSA) releases the relevant downlink message matching and forwarding rule, triggering the end marking (END MARKER) process;

At this time, the downlink of the UE is on by New UPF (PSA), T-RAN.

Steps 87 and 88: the SMF network element forwards user plane information (such as CN Tunnel Info) of New UPF (PSA) to the T-RAN;

at this point, the UE, T-RAN, new UPF (PSA) uplink is on.

Steps 89 and 810: release the resources and execute the registration procedure.

Step 811: releasing Old UPF (PSA).

It should be noted that, if the method is adopted, the problem of the UE IP address pool corresponding to different PSAs may be brought, and different PSAs accessing the same DNAI may be restricted to share the same UE IP address in the deployment, or the UE IP address may be reassigned after the new PSA is selected and updated and mapped correspondingly. Specifically, for the problem of allocation of the UE IP address, the embodiment of the present invention is not specifically limited.

Example 2: an Xn is switched, a new PSA with different DNAI is accessed, a session management process of SSC mode 2 or SSC mode 3 is executed, namely, a PDU session anchor point is changed, and a changed second PDU session anchor point is different from a first DNAI of a data network accessed by the first PDU session anchor point, and then the session management process of SSC mode 2 or SSC mode 3 with the changed PDU session anchor point is executed. As shown in fig. 9, the method specifically comprises the following steps:

Step 90: before the handover procedure of the core network Xn, the related handover procedure has been completed between the source access network node (S-RAN) and the target access network node (T-RAN), since the T-RAN has obtained the Old PSA (Old UPF (PSA), i.e. the user plane information of the first PDU session anchor before handover (e.g. CN Tunnel Info), at this time:

The transmission path of the Uplink (UL) packet is: UE, T-RAN, old UPF (PSA).

Step 91: the T-RAN sends an N2 path switching request to the AMF network element.

Step 92: the AMF network element sends an SM uplink update request to the SMF network element.

Step 93: the SMF network element performs UPF selection, if new PSA which can be accessed to the same DNAI as the old PSA and is better than the old PSA is not found, the SMF network element can select new PSA of new DNAI which can be accessed to the same DNN and S-NSSAI;

wherein selecting new PSA may be based on factors such as local policy of SMF network element, SSC mode, UPF capability, UPF load, etc.

Step 94: if the new PSA decided by the SMF network element corresponds to the new TARGET DNAI, the SMF network element invokes Nsmf _ PDUSession _ SMContextStatusNotify Request (TARGET DNAI info) service operation to the AMF network element and indicates whether the AMF network element needs to perform SMF reselection.

It should be noted that: the New UPF (PSA) selected by the SMF network element herein is mainly used to distinguish between different scenarios, which may not be necessarily used in the subsequent flow in the flow of fig. 9.

Step 95: based on the SSC mode, a corresponding release-before-reestablishment SSC mode 2 procedure, or a release-before-reestablishment SSCI mode 3 procedure, is performed, and will not be described again.

Example 3: n2 switching, accessing the new PSA of the same DNAI;

as shown in fig. 10, for the N2 handover preparation phase, it includes:

step 101: the S-RAN sends a handover request to a source AMF (S-AMF) network element.

Step 102: the S-AMF network element executes target AMF selection to determine a target AMF (T-AMF) network element.

Step 103: the S-AMF network element sends a request to the T-AMF network element to create a UE context, i.e. invokes Namf _communication_ CreateUEContext Request service operation.

Step 104: the T-AMF network element sends an update session management context request to the SMF network element, i.e. invokes Nsmf _ PDUSession _ UpdateSMContext Request service operations.

Step 105: the SMF network element performing UPF selection, comprising:

Steps 106a and 106b: the SMF network element establishes an N4 session with a New UPF (PSA), and requests the New UPF (PSA) to allocate corresponding user plane information (such as tunnel information), and the New UPF (PSA) feeds back the corresponding user plane information (such as tunnel information) to the SMF through a response message.

Step 107: the SMF network element feeds back an update session management context response to the T-AMF network element.

Step 108 and step 109: the T-AMF network element performs PDU handover response supervision and sends a handover request to the T-RAN;

In this process, the SMF network element sends user plane information (such as CN Tunnel Info) of New UPF (PSA) to the T-RAN, and the T-RAN opens up an uplink between the New UPF (PSA).

Step 1010: the T-RAN feeds back a handover request acknowledgement to the T-AMF network element.

Steps 1011a to f: if an indirect forwarding path is required between the S-RAN and the T-RAN (i.e., S-RAN, S-UPF, T-UPF, T-RAN), an indirect forwarding path between the Old PSA and the New PSA is created (i.e., S-RAN, old PSA, new PSA, T-RAN), and buffered DL packets sent by the Old PSA to the S-RAN are forwarded to the T-RAN and sent to the UE.

Step 1012: the T-AMF network element sends a UE context creation response to the S-AMF network element.

As shown in fig. 11, the execution phase for the N2 handover includes:

Steps 111 and 112: the S-AMF network element sends a switching instruction to the UE through the S-RAN.

Wherein, steps 112 a-c: the S-RAN transmits the uplink RAN state to the S-AMF network element, the S-AMF network element transmits the N1N2 message with the T-AMF network element, and the T-AMF network element transmits the downlink RAN state to the T-RAN.

Steps 113a and 113b: direct data forwarding and indirect data forwarding. For downlink data packets, if the data forwarding is indirect data forwarding between the S-RAN and the T-RAN, the forwarding path is S-RAN, old PSA, new PSA and T-RAN; the indirect forwarding path for step 1103b is located between the old PSA and the new PSA.

Step 114: the UE feeds back a handover determination to the T-RAN, i.e. the UE-to-T-RAN link is opened, the uplink between the UE, T-RAN, new UPF (PSA) is opened.

Step 115: the T-RAN sends a handover notification to the T-AMF network element.

Steps 116 a-c: the T-AMF network element and the S-AMF network element inform the handover through N2 information, and the S-AMF network element sends an SM context release request to the SMF network element, namely, call Nsmf _ PDUSession _ ReleaseSMContext Request service operation.

Step 117: the T-AMF network element sends an update SM context request to the SMF network element, i.e. invokes Nsmf _ PDUSession _ UpdateSMContext Request service operations.

Steps 118 a-b and steps 119 a-b: an indirect forwarding path release between New UPF (PSA) and Old UPF (PSA);

in the process, the SMF network element forwards user plane information (such as AN Tunnel Info) of the T-RAN to New UPF (PSA);

up to this point, the downlink between New UPF (PSA), T-RAN, UE is on.

Step 1110: the SMF network element sends an update SM context response to the T-AMF network element.

Step 1111: a registration procedure is performed.

Steps 1112 a-b: releasing Old UPF (PSA).

Steps 1113 a-b: releasing the S-RAN.

Example 4: n2 is switched to access new PSA of different DNAI, and session management process of SSC mode 2 or SSC mode 3 is executed. As shown in fig. 12, the method specifically comprises the following steps:

step 121: the S-RAN sends a switching requirement to the S-AMF network element.

Step 122: the S-AMF network element executes target AMF selection to determine a target AMF (T-AMF) network element.

Step 123: the S-AMF network element sends a request to the T-AMF network element to create a UE context, i.e. invokes Namf _communication_ CreateUEContext Request service operation.

Step 124: the T-AMF network element sends an update session management context request to the SMF network element, i.e. invokes Nsmf _ PDUSession _ UpdateSMContext Request service operations.

Step 125: the SMF network element performs UPF selection and if no new PSA is found that can be accessed to the same DNAI as the old PSA, which is better than the old PSA, the SMF network element can select new PSA of new DNAI that is accessed to the same DNN and S-NSSAI.

Step 125a: and the SMF network element and the T-AMF carry out SM context state notification.

Step 126: based on the SSC mode of the session, a corresponding release-before-reestablishment SSC mode 2 session management procedure is performed, or a corresponding release-before-reestablishment SSC mode 3 session management procedure is performed.

In the above scheme of the present invention, when the core network element (such as the SMF network element) is triggered to select the user plane function node due to the mobile handover of the UE, the core network element increases the selection factor of the SSC mode based on the current session, and may allow updating the PDU session anchor point in the handover process, so that a better user plane path is selected in the handover process. If the updated PDU session anchor point and the pre-updated PDU session anchor point can access the same DNAI data network, executing the N4 session establishment flow with the updated PDU session anchor point and switching to a new user plane path; if the updated PDU session anchor accesses a different DNAI data network than the pre-update PDU session anchor, then a corresponding SSC mode 2 or SSC mode 3 procedure is performed to reestablish the session and user-plane paths. In this way, by allowing the user plane function node selection to be performed when updating the PDU session anchor point in the handover process based on the selection factor of the SSC mode of the current session in the mobile handover process of the terminal, signaling overhead generated by repeatedly updating the user path in the mobile handover process and the session management process of the SSC mode can be reduced, and the delay can be reduced advantageously.

The access network node according to the embodiment of the present application may be a base station, where the base station may include a plurality of cells for providing services for the terminal. Depending on the particular application, a base station may also be referred to as a device in an access network that communicates over the air-interface, through one or more sectors, with wireless terminal devices, or by other names. The base station may be configured to exchange received air frames with internet protocol (Internet Protocol, IP) packets as a router between the wireless terminal device and the rest of the access network, which may include an Internet Protocol (IP) communication network. The network device may also coordinate attribute management for the air interface. For example, the base station according to the embodiment of the present application may be a base station (Base Transceiver Station, BTS) in a global system for mobile communications (Global System for Mobile communications, GSM) or code division multiple access (Code Division Multiple Access, CDMA), a base station (NodeB) in a wideband code division multiple access (Wide-band Code Division Multiple Access, WCDMA), an evolved base station (evolutional Node B, eNB or e-NodeB) in a long term evolution (long term evolution, LTE) system, a 5G base station (gNB) in a 5G network architecture (next generation system), a home evolved base station (Home evolved Node B, heNB), a relay node (relay node), a home base station (femto), a pico base station (pico), and the like. In some network structures, a base station may include a centralized unit (centralized unit, CU) node and a Distributed Unit (DU) node, which may also be geographically separated.

The above embodiments are described with respect to the mobile handover method of the present invention, and the following embodiments will further describe the corresponding core network element with reference to the accompanying drawings.

Specifically, as shown in fig. 13, an embodiment of the present invention provides a mobile switching device, including a memory 131, a transceiver 132, and a processor 133; wherein the memory 131 is for storing a computer program; the transceiver 132 is used for receiving and transmitting data under the control of the processor 133; such as transceiver 132, for receiving and transmitting data under the control of processor 133; the processor 133 is configured to read the computer program in the memory 131 and perform the following operations:

in the mobile switching process of the terminal, user plane function node selection is executed according to the session of the session and the service continuity SSC mode;

Optionally, the processor 133 is configured to read the computer program in the memory 131 and perform the following operations:

under the condition that the SSC mode is SSC mode 1, determining an intermediate user plane function node under the condition that a protocol data unit PDU session anchor point is not changed;

and/or the number of the groups of groups,

Optionally, the target PDU session anchor includes one of:

a terminal moves a first PDU session anchor point before switching;

a second PDU session anchor identical to a first data network access identifier DNAI of a data network to which the first PDU session anchor is to be accessed;

Optionally, in case of changing PDU session anchor when performing user plane function node selection, the processor 133 is configured to read the computer program in the memory 131 and perform the following operations:

and/or the number of the groups of groups,

Wherein in fig. 13, a bus architecture may comprise any number of interconnected buses and bridges, and in particular one or more processors represented by processor 133 and various circuits of memory represented by memory 131, linked together. The bus architecture may also link together various other circuits such as peripheral devices, voltage regulators, power management circuits, etc., which are well known in the art and, therefore, will not be described further herein. The bus interface provides an interface. The transceiver 132 may be a plurality of elements, i.e., including a transmitter and a receiver, providing a means for communicating with various other apparatus over transmission media, including wireless channels, wired channels, optical cables, and the like. The processor 133 is responsible for managing the bus architecture and general processing, and the memory 131 may store data used by the processor 133 in performing operations.

The processor 133 may be a Central Processing Unit (CPU), application SPECIFIC INTEGRATED Circuit (ASIC), field-Programmable gate array (Field-Programmable GATE ARRAY, FPGA), or complex Programmable logic device (Complex Programmable Logic Device, CPLD), or the processor may employ a multi-core architecture.

It should be noted that, the above device provided in the embodiment of the present invention can implement all the method steps implemented in the method embodiment and achieve the same technical effects, and detailed descriptions of the same parts and beneficial effects as those in the method embodiment in this embodiment are omitted.

In order to better achieve the above object, as shown in fig. 14, an embodiment of the present invention provides a core network element 1400, including:

A first processing unit 1410, configured to perform user plane function node selection according to a session of a session and a service continuity SSC mode in a terminal mobile handover process;

A second processing unit 1410 is configured to perform a corresponding handover procedure for the selected user plane function node.

Optionally, the first processing unit 1410 is configured to:

and/or the number of the groups of groups,

Optionally, the target PDU session anchor includes one of:

a terminal moves a first PDU session anchor point before switching;

Optionally, in case of changing the PDU session anchor when performing user plane function node selection, the second processing unit 1420 is configured to:

and/or the number of the groups of groups,

Optionally, the second processing unit 1420 is configured to:

Optionally, the second processing unit 1420 is further configured to:

Optionally, the second processing unit 1420 is configured to:

and/or the number of the groups of groups,

It should be noted that, in the embodiment of the present application, the division of the units is schematic, which is merely a logic function division, and other division manners may be implemented in actual practice. In addition, each functional unit in the embodiments of the present application may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.

The integrated units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a processor-readable storage medium. Based on such understanding, the technical solution of the present application may be embodied in essence or a part contributing to the prior art or all or part of the technical solution in the form of a software product stored in a storage medium, including several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) or a processor (processor) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (Random Access Memory, RAM), a magnetic disk, or an optical disk, or other various media capable of storing program codes.

It should be noted that, the core network element provided by the embodiment of the present invention can implement all the method steps implemented by the embodiment of the present invention, and can achieve the same technical effects, and detailed descriptions of the same parts and beneficial effects as those of the embodiment of the present invention are omitted herein.

The embodiment of the present invention further provides a processor readable storage medium, where the processor readable storage medium stores a computer program, where the computer program is configured to enable the processor to execute the steps of the method for mobile handover, and the steps of the method for mobile handover can achieve the same technical effects, and detailed descriptions of the same parts and beneficial effects as those of the method embodiment in the present embodiment are omitted.

The processor-readable storage medium may be any available medium or data storage device that can be accessed by a processor, including, but not limited to, magnetic storage (e.g., floppy disks, hard disks, magnetic tape, magneto-optical disks (MOs), etc.), optical storage (e.g., CD, DVD, BD, HVD, etc.), and semiconductor storage (e.g., ROM, EPROM, EEPROM, non-volatile storage (NAND FLASH), solid State Disk (SSD)), etc.

The terminal according to the embodiment of the application can be a device for providing voice and/or data connectivity for a user, a handheld device with a wireless connection function, or other processing devices connected to a wireless modem, etc. The names of the terminal devices may also be different in different systems, for example in a 5G system, the terminal devices may be referred to as User Equipment (UE). The wireless terminal device may communicate with one or more Core Networks (CNs) via a radio access Network (Radio Access Network, RAN), which may be mobile terminal devices such as mobile phones (or "cellular" phones) and computers with mobile terminal devices, e.g., portable, pocket, hand-held, computer-built-in or vehicle-mounted mobile devices that exchange voice and/or data with the radio access Network. Such as Personal communication services (Personal Communication Service, PCS) phones, cordless phones, session initiation protocol (Session Initiated Protocol, SIP) phones, wireless local loop (Wireless Local Loop, WLL) stations, personal digital assistants (Personal DIGITAL ASSISTANT, PDA) and the like. The wireless terminal device may also be referred to as a system, subscriber unit (subscriber unit), subscriber station (subscriber station), mobile station (mobile station), remote station (remote station), access point (access point), remote terminal device (remote terminal), access terminal device (ACCESS TERMINAL), user terminal device (user terminal), user agent (user agent), user equipment (user device), and embodiments of the present application are not limited.

It will be appreciated by those skilled in the art that embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, magnetic disk storage, optical storage, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer-executable instructions. These computer-executable instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These processor-executable instructions may also be stored in a processor-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the processor-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These processor-executable instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

Furthermore, it should be noted that in the apparatus and method of the present invention, it is apparent that the components or steps may be disassembled and/or assembled. Such decomposition and/or recombination should be considered as equivalent aspects of the present invention. Also, the steps of performing the series of processes described above may naturally be performed in chronological order in the order of description, but are not necessarily performed in chronological order, and some steps may be performed in parallel or independently of each other. It will be appreciated by those of ordinary skill in the art that all or any of the steps or components of the methods and apparatus of the present invention may be implemented in hardware, firmware, software, or a combination thereof in any computing device (including processors, storage media, etc.) or network of computing devices, as would be apparent to one of ordinary skill in the art after reading this description of the invention.

It will be apparent to those skilled in the art that various modifications and variations can be made to the present application without departing from the spirit or scope of the application. Thus, it is intended that the present application also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Claims

1. A mobile switching method, comprising:

In the mobile switching process of the terminal, a core network element executes user plane function node selection according to the session of the session and the SSC mode of service continuity;

2. The mobile switching method of claim 1, wherein the core network element performs user plane function node selection according to a session and service continuity SSC mode of the session, comprising:

and/or the number of the groups of groups,

3. The mobile switching method of claim 2, wherein the target PDU session anchor comprises one of:

a terminal moves a first PDU session anchor point before switching;

4. A mobile handover method according to any of claims 1 to 3, wherein in case of changing PDU session anchor when performing user plane function node selection, the core network element performs a corresponding handover procedure for the selected user plane function node, comprising:

and/or the number of the groups of groups,

5. The mobile switching method of claim 4, wherein the core network element performs a session management procedure associated with the second PDU session anchor, comprising:

6. The mobile switching method of claim 5, wherein before the core network element releases the user plane path between the source access network node and the first PDU session anchor point, further comprising:

7. The mobile switching method according to claim 5 or 6, wherein the core network element establishes an N4 session with the second PDU session anchor point, and constructs a user plane path between a target access network node to which the terminal is switched and the second PDU session anchor point through message interaction, comprising:

8. The mobile switching method of claim 7, wherein the sending the user plane information of the target access network node to the second PDU session anchor point comprises:

9. The mobile switching method according to claim 4, wherein the core network element performs a session management procedure of SSC mode 2 or SSC mode 3, comprising:

and/or the number of the groups of groups,

10. A mobile switching device, which is characterized by comprising a memory, a transceiver and a processor;

11. The mobile switching device of claim 10, wherein the processor is configured to read the computer program in the memory and perform the following operations:

and/or the number of the groups of groups,

12. The mobile switching apparatus of claim 11 wherein the target PDU session anchor comprises one of:

a terminal moves a first PDU session anchor point before switching;

13. Mobile switching apparatus according to any of claims 10 to 12, wherein in case of changing PDU session anchor when performing user plane function node selection, the processor is adapted to read the computer program in the memory and to perform the following operations:

and/or the number of the groups of groups,

14. The mobile switching device of claim 13, wherein the processor is configured to read the computer program in the memory and perform the following operations:

15. The mobile switching device of claim 14, wherein the computer program for reading in the memory by the processor further performs the operations of:

16. The mobile switching device of claim 14 or 15, wherein the processor is configured to read the computer program in the memory and perform the following operations:

17. The mobile switching device of claim 16, wherein the processor is configured to read the computer program in the memory and perform the following:

18. The mobile switching device of claim 13, wherein the processor is configured to read the computer program in the memory and perform the following operations:

and/or the number of the groups of groups,

19. A core network element comprising:

The first processing unit is used for executing user plane function node selection according to the session of the session and the service continuity SSC mode in the mobile switching process of the terminal;

20. A processor-readable storage medium, characterized in that the processor-readable storage medium stores a computer program for causing the processor to execute the steps of the mobile handover method according to any one of claims 1 to 9.