CN101291453B

CN101291453B - Method and apparatus for implementing voice continuity of conversation

Info

Publication number: CN101291453B
Application number: CN2007101027622A
Authority: CN
Inventors: 吴晓波; 派崔斯·赫德; 张戬; 王云贵
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2007-04-17
Filing date: 2007-04-24
Publication date: 2012-08-08
Anticipated expiration: 2027-04-24
Also published as: CN101291453A

Abstract

The invention provides a method for realizing the voice continuity of a session and a device. The method comprises the following steps that: when the switching is needed between a source network and a target network, the technical proposal that the voice continuity is realized on a bearing level can be adopted; if a target network grouping domain does not support VoIP, the signaling bearer of the session is switched to the target network grouping domain, and the voice bearer of the session is switched to a target network circuit domain; a PCC framework is utilized to process a subsequent signaling which is switched from the source network to the target network circuit domain in order that the whole process of the voice continuity keeps transparent to a business network; on the basis of not needing to upgrade and reform the business network, the voice business continuity of the session and the normal use of other business in the business network are ensured; at the same time, when the target network needs to be switched to the source network subsequently, the PS switching from the target network to the source network is utilized to trigger that the voice data and the signaling of the subsequent session are switched back to the source network.

Description

Method and device for realizing voice continuity of conversation

Technical Field

The present invention relates to the field of communications technologies, and in particular, to a method and an apparatus for implementing voice continuity of a session.

Background

With the development of SAE/LTE (System Architecture Evolution/Long Term Evolution) network technology, SAE/LTE networks have covered some urban areas and traffic hot spots, resulting in coexistence of SAE/LTE networks and 2G/3G (2rd Generation/3rd Generation, second Generation mobile communication technology/third Generation mobile communication technology) networks in current communication networks. The user who initiates the call may cross two networks during one call, and in order to ensure that the user's call is not interrupted, a handover between the SAE/LTE network and the 2G/3G network is required.

For different network bearer mechanisms, the service applications of mobile communication can be classified into the following categories:

the first type is Circuit domain Service (CS) using Circuit bearers, such as voice communication, short message or multimedia message;

the second type is Packet switched Packet Service (PS), such as data communication or interactive video Service;

the third type is an IP (Internet Protocol) supported mobile IP multimedia Service Subsystem application (IMS), such as providing Quality of Service (QoS) voice, data, and multimedia integrated services, to implement Service convergence between the mobile communication network and the Internet network.

The SAE/LTE network is used as a Packet switching System, in which voice service can only be carried and transmitted over a Packet System (PS). In an SAE/LTE network, IMS controls Voice traffic through an IP-based network, so in an SAE/LTE network, Voice traffic is generally called VoIP (Voice over IP) Voice traffic, while in a 2G/3G network, Voice traffic is generally carried over CS TDM (Circuit System Time Division Multiplexing) due to lack of support for VoIP Voice traffic.

After years of development, a 2G/3G network can be regarded as a comprehensive coverage to some extent, and due to differences in deployment between an SAE/LTE network and the 2G/3G network and differences in mobile communication service bearer mechanisms in different networks, when a UE (User Equipment) moves out of a coverage area of a base station of the SAE/LTE network and enters a coverage area of the base station of the 2G/3G network, if the UE has an IMS voice service that is carried in the SAE/LTE network, a break of the IMS voice service may occur, thereby affecting continuity of the voice service of the User.

In order to solve the above problems and ensure the Continuity of the user voice service, currently, an SRV (Single Radio voice Continuity between IMS and CS) technical scheme is adopted, which solves the problem of the Continuity of the IMS voice carried on the SAE/LTE network and the voice carried on the CS TDM.

The SRV technical solution is premised on the terminal being unable to receive and transmit data in the SAE/LTE network and the 2G/3G network or other 3GPP networks simultaneously.

The SRV scheme is based on inter-MSC handover (inter-MSC handover), where an MME (mobility management Entity) in the SAE/LTE network is emulated as an anchor MSC (Mobile switching Center), and there is an "E" interface between the MME and the MSC for simulating inter-MSC handover, thereby providing an interface for data exchange between the SAE/LTE network and the 2G/3G network.

FIG. 1 is a diagram of a UE in an SAE/LTE network, in which the UE acquires an IP connection through the SAE/LTE network and registers in an IMS network, and the UE has an IMS voice call, and at this time, both IMS signaling and VoIP voice services are carried in an SAE/LTE PS domain.

When UE enters into 2G/3G network from SAE/LTE network, VoIP voice service bearer can be transferred to 2G/3G CS domain by switching PS domain to CS domain, Serving/PDN SAE Gateway (Serving/packet data network system evolution network Gateway) is used as end point of SIP (Session Initiation Protocol) signaling and data, meanwhile, P-CSCF (Proxy-Call Session Control Function) must be used as UE Proxy to perform SIP registration (i.e. to register with IMS) in order to keep SIP Session.

After switching from SAE/LTE network to 2G/3G CS domain, Serving/PDN SAE Gateway also needs to have ISUP (ISDN User Part) signaling capability for converting SIP signaling into corresponding content; moreover, in subsequent handovers from the 2G/3G CS domain back to the SAE/LTE network, since the base station and MSC cannot normally perform the handover from the CS domain to the PS domain, there is also a need for an upgrade to the 2G/3G network in order to enable the handover from the 2G/3G network back to the SAE/LTE network. As shown in FIG. 2, a schematic diagram of an existing UE switching from an SAE/LTE network to a 2G/3G network is shown.

Hereinafter, the handover procedure between the SAE/LET network and the GSM network will be described by taking only a GSM (Global System for Mobile Communications, second generation Global System for Mobile Communications) network in the 2G network as an example.

Fig. 3 shows a flow chart of switching from an SAE/LTE network to a GSM network in the prior art, which includes the following specific steps:

there is one IMS voice session in the 3-1, SAE/LTE network. If the P-CSCF detects that the voice session may need to be handed over from the SAE/LTE network to the GSM CS domain, it notifies the eNodeB (base station of SAE/LTE system) through PCRF (Policy and Charging Rules Function) that the session may need to be handed over to vcc (voice call continuity);

the IMS voice conversation is carried out between UE and Serving/PDN SAE Gateway/MGW, and VoIP voice service data is transmitted on RTP (Real Time Transport Protocol) flow;

3-2, after receiving the notification of MME switching, the eNodeB sends the related adjacent GSM cells to the UE through an adjacent cell list, and then the UE reports the measurement report to the eNodeB;

3-3, the eNodeB decides which GSM CS domain to switch from the SAE/LTE network according to the received UE measurement report, and the eNodeB sends a request message for switching from the SAE/LTE network to the GSM CS domain to the MME;

3-4, after the MME receives the switching message, initiating a basic inter-MSC handover;

since the MME is emulated as an anchor MSC, the MSC-S/MGW (Mobile switching Center-Server/Mediagateway) does not know to be the MME-initiated inter-MSC handover. When establishing MSC-S/MGW and Serving/PDN SAE Gateway interoffice link, Serving/PDN SAE Gateway is correspondingly regarded as MGW;

3-5, MME sends encryption key request (IMSI) to MSC-S/MGW.

3-6, MSC-S/MGW returns response to MME, the response message includes encryption key or unknown part;

3-7, after the encryption key is determined, the MME loads the encryption key in a message for preparing a switching request and sends the message to the MSC-S;

3-8, 3-9, 3-10 and common CS switching processing flows; because the GSM BSC (Base Station Controller) and MSC-S (mobile switching center server) do not know that the switching is from a special PS domain to a CS domain, the GSM BSC (Base Station Controller) and the MSC-S (mobile switching center server) are used as common CS domain switching processing to complete the CS domain switching;

3-11, 3-12, MME regards Serving/PDN SAE Gateway as MGW, and organizes the establishment of link between Serving/PDN SAE Gateway and MSC-S/MGW.

3-13, MME sends a handover command to eNodeB, which forwards the message to the UE. The handover command instructs the UE to handover from the PS domain to the CS domain and to use the correct encryption key;

3-14, accessing the UE into the target cell, and sending a switching completion message by the UE through the MSC-S;

3-15, MSC-S transmits the switching completion message to MME;

if the called MS is off-hook, the called MSC sends a response message (ANSWER) back to the calling MSC, and at the moment, the link between the calling and the called is connected;

3-16, MME informs Serving/PDN SAE Gateway to activate user plane and informs PCRF;

MME informs eNodeB to release the wireless resources of the original SAE/LTE network;

if the process of switching from PS domain to CS domain fails, MME will notify Serving/PDN SAE Gateway and steps 3-17 to 3-21 will not be executed;

3-17, Serving/PDN SAE Gateway sends out link update message to PCRF. The Serving/PDN SAE Gateway informs the PCRF that the IMS voice session is terminated at the Serving/PDN SAE Gateway, and simultaneously the Serving/PDN SAE Gateway informs the PCRF of an IP address and a port sent by a subsequent SIP signaling related to the UE;

3-18, PCRF informs P-CSCF of the link update message;

3-19, the PCRF returns a link update response to the Serving/PDN SAE Gateway;

3-20, if the registration of the UE on the IMS cannot be maintained, the P-CSCF is required to register with the IMS with the identity of the UE.

3-21, P-CSCF sends re-invite message to S-CSCF, informs Serving/PDN SAE Gateway to allocate IP address and port, and provides the allocated IP address and port for the subsequent VoIP voice service data.

At this time, the process of switching the UE from the SAE/LTE network to the GSM network can be completed through the steps, and the voice session is switched from the SAE/LTE network to the GSM CS domain through the switching from the PS domain to the CS domain, so that the continuity of the voice service of the user is ensured; however, in order to ensure normal transmission of SIP signaling and data, the IMS network needs to be upgraded and modified, which affects the applicable range of the SRV technical solution.

When the UE moves out of the coverage area of the GSM network base station and enters the coverage area of the SAE/LTE network base station, the SRV technical scheme may be adopted to ensure the continuity of the voice service of the user. As shown in fig. 4, a flowchart of the existing subsequent handover from GSM to SAE/LTE network includes the following specific steps:

4-1, BSC (Base Station Controller) sends common MSC switching request to MSC-S/MGW;

4-2, MSC-S/MGW forwards a request for preparing subsequent switching to MME;

4-3, the MME analyzes the stored PS domain key and sends a switching request to the eNodeB;

4-4, the eNodeB executes corresponding handover preparation and sends a handover request response to the MME;

4-5, the MME informs Serving/PDN SAE Gateway to prepare a user plane;

4-6, Serving/PDN SAE Gateway returns a response for preparing a user plane to the MME;

4-7, sending a switching command to the BSC by Serving/PDN SAE Gateway, and forwarding the switching command to the UE by the BSC;

4-8, the UE sends a switching completion message to the eNodeB, and the eNodeB forwards the switching completion message to the MME;

4-9, MME indicates Serving/PDN SAE Gateway to use PS domain to transmit uplink user data and informs PCRF, UE returns to SAE/LTE network again;

4-10, releasing the target CS domain resource;

4-11, Serving/PDN SAE Gateway sends the bearing information required by the network to the UE, so that the SAE/LTE network establishes IP bearing;

4-12, at any time after the step 4-8, the UE sends a re-invite message to the P-CSCF, and the P-CSCF contacts the S-CSCF. At this point, the user plane data is re-terminated at the UE.

Through the steps, after the user upgrades the GSM network base station and the MSC, the GSM network can complete the switching from the CS domain to the PS domain, thereby realizing the continuity of the voice service of the user in the subsequent process of switching from the GSM network to the SAE/LTE network.

From the foregoing, it can be seen that the following problems exist in the prior art:

1. the P-CSCF is required to have the capability of detecting that the voice session is to be switched from the SAE/LTE network to the GSM CS domain, and the corresponding modification is required to be carried out on the IMS network;

2) after the SAE/LTE network is switched to a GSM CS domain, Serving/PDN SAE Gateway is used as a termination point of SIP signaling and data, and the P-CSCF can be informed of the SIP signaling and data IP address related to the subsequent UE through the PCRF and then the called UE is informed of the P-CSCF through the Re-Invite, so that the IMS network needs to be modified and upgraded correspondingly;

in addition, after the SAE/LTE network is switched to the GSM CS domain, in order to maintain the SIP session, the P-CSCF must be registered to the IMS as a UE agent, and corresponding modification and upgrade also need to be carried out on the IMS network;

3) after switching from SAE/LTE network to GSM CS domain, the complexity of Serving/PDN SAE Gateway can be increased due to the requirement that Serving/PDN SAE Gateway has the capability of converting SIP signaling into ISUP signaling with corresponding content;

4) when the SAE/LTE network is switched to the GSM CS domain, the services based on the IP in the IMS network can not be normally used because the IP data can not be normally transmitted;

5) if the GSM network is switched to the SAE/LTE network subsequently, the GSM network needs to be upgraded because the base station and the MSC in the GSM network cannot complete the switching from the CS domain to the PS domain.

Disclosure of Invention

The embodiment of the invention provides a method and a device for realizing voice continuity of a session at a bearing layer.

The purpose of the embodiment of the invention is realized by the following technical scheme:

the embodiment of the invention provides a method for realizing voice continuity of a conversation, which comprises the following steps:

if the session is a session needing to maintain voice continuity, when the session needs to be switched from a source network to a target network;

transferring signaling bearers of the session to the target network PS domain;

and transferring the voice data bearer of the session to the target network CS domain.

The embodiment of the invention provides a method for judging voice continuity conversation, which comprises the following steps:

when a network is attached or a bearer is established, a terminal reports the capability of maintaining voice continuity, or the capability of maintaining voice continuity of the terminal is statically configured in advance in the network;

and according to the capability of the terminal needing to keep the voice continuity, the network side determines that the session initiated by the terminal is the session needing to keep the voice continuity.

The embodiment of the invention provides a method for realizing voice continuity of a conversation, which is characterized by comprising the following steps:

if the conversation is the conversation needing to maintain the voice continuity, receiving a measurement report of the terminal;

the network side determines that the session needs to be switched from a source network to a target network according to the measurement report;

transferring the voice data bearer of the session to the target network PS domain or the target network CS domain;

transferring the signaling bearer of the session to a target network Packet (PS) domain or transferring the signaling bearer of the session to a remote user agent.

if the IMS session is a session needing to maintain voice continuity, when the IMS session needs to be switched from a source network to a target network;

transferring signaling data of the IMS session to a remote user agent;

and transferring the voice data bearer of the IMS session to the target network CS domain.

The embodiment of the invention provides a base station, which comprises:

the first receiving module is used for receiving a measurement report sent by a terminal;

the judging module is used for judging that the session needs to be switched according to the measurement report;

the processing module is used for transferring the signaling bearer of the session to the PS domain of the target network when the session needs to be switched from a source network to the target network; and transferring the voice data bearer of the session to the target network CS domain.

The embodiment of the invention provides a device for realizing voice continuity of a conversation, which comprises:

the receiving module is used for receiving a measurement report sent by a terminal;

the first judging module is used for judging that the session needs to be switched according to the measurement report;

and the processing module is used for switching the session from the source network to the target network when the session needs to be switched from the source network to the target network.

It can be seen from the technical solutions provided in the embodiments of the present invention that, when handover needs to be performed between a source network and a target network, a technical solution for implementing SRV on a bearer level may be adopted.

If the target network packet domain does not support VoIP, the bearing of IMS signaling is switched to the packet domain of the target network, the IMS voice bearing is switched to the circuit domain of the target network, and the PCC architecture is utilized to process the subsequent signaling switched from the source network to the circuit domain of the target network, so that the whole process of SRV switching is transparent to the IMS network, the switching process is simplified, and the continuity of the IMS network voice service of a user and the normal use of other services of the IMS network are ensured on the basis of not upgrading and modifying the IMS network; meanwhile, when the target network needs to be switched back to the source network subsequently, the PS switching from the target network to the source network can be utilized to trigger the subsequent voice data and IMS signaling to be switched back to the source network, meanwhile, the PS switching process can also trigger the reestablishment of other data services, and the target network does not need to be upgraded.

If the target network packet domain supports VoIP, the signaling load and the voice load of the session are switched to the packet domain of the target network.

If the target network does not support the packet domain, the signaling bearer of the session is switched to the RUA (Remote User Agent), the voice bearer of the session is switched to the circuit domain of the target network, and the PCC architecture is utilized to process the subsequent signaling switched from the source network to the circuit domain of the target network, so that the whole process of voice continuity is transparent to the service network, and the continuity of the voice service of the session and the normal use of other services of the service network are ensured on the basis of not upgrading and reconstructing the service network.

Drawings

FIG. 1 is a schematic diagram of a UE in an SAE/LTE network;

FIG. 2 is a diagram illustrating a conventional handover from an SAE/LTE network to a 2G/3G network;

FIG. 3 is a schematic diagram illustrating a conventional handover procedure from an SAE/LTE network to a 2G/3G network;

FIG. 4 is a schematic diagram illustrating a conventional subsequent handover procedure from a 2G/3G network to an SAE/LTE network;

FIG. 5 is a schematic diagram of switching from an SAE/LTE network to a 2G/3G network according to an embodiment of the present invention;

FIG. 6 is a flowchart of switching an IMS voice service from an SAE/LTE network to a 2G/3G network according to an embodiment of the present invention;

FIG. 7 is a schematic diagram of a subsequent flow for switching an IMS voice service from an SAE/LTE network to a 2G/3G network according to an embodiment of the present invention;

FIG. 8 is a flowchart illustrating a subsequent procedure of switching an IMS voice service from a 2G/3G network to an SAE/LTE network according to an embodiment of the present invention;

FIG. 9 is a flowchart illustrating a subsequent procedure of switching an IMS voice service from a 2G/3G network to an SAE/LTE network according to an embodiment of the present invention;

FIG. 10 is a diagram illustrating a UE initiating an IMS voice call in an SAE/HSPA network according to an embodiment of the present invention;

FIG. 11 is a schematic diagram of a handover from an SAE/HSPA network to a 2G/3G network according to an embodiment of the present invention;

FIG. 12 is a flowchart of switching an IMS voice service from an SAE/LTE network to a 2G/3G network (introducing SRVMGW) according to an embodiment of the present invention;

FIG. 13 is a flowchart of switching an IMS voice service from an SAE/LTE network to a 2G/3G network (introducing SRVMGW and RUA) according to an embodiment of the present invention;

FIG. 14 is a subsequent flowchart of switching IMS voice service from SAE/LTE network to 2G/3G network (SRV MGW and RUA are introduced) according to the embodiment of the present invention.

Detailed Description

The embodiment of the invention relates to a method for maintaining voice continuity between a source network (generally, the source network supports VoIP voice services, such as an LTE network or an HSPA +) and a target network (generally, the target network does not support the VoIP voice services, such as a 2G/3G network).

When UE initiates an IMS voice call and triggers the process of establishing a load from a network side, a core network judges that the session is an SRV session according to the SRV capability of the UE and informs the UE to carry out corresponding measurement; when a wireless side receives a measurement report of UE, if the target network PS domain is judged to be incapable of bearing IMS voice data, the IMS signaling bearing is transferred to the target network PS domain, and the IMS voice data signaling bearing is transferred to the target network CS domain, so that the SRV switching process is realized on the bearing level, and a PCC architecture is utilized to process the switched subsequent signaling;

if the target network can not bear the VoIP voice service, the IMS signaling bearer is transferred to the PS domain of the target network through PS switching, an IMRN Number (IP Media Routing Number) is distributed by the core network and is sent to the UE together with a PS switching command, the UE establishes the CS domain bearer of the target network between the UE and the core network according to the IMRN Number, and the core network associates the CS domain bearer with the corresponding PS domain bearer according to the IMRN Number.

If the target network packet domain supports VoIP voice service, the signaling load and voice load of the session are switched to the packet domain of the target network.

If the target network does not support the packet domain, the signaling bearer of the session is switched to the RUA, the voice bearer of the session is switched to the circuit domain of the target network, and the PCC architecture is utilized to process the subsequent signaling switched from the source network to the circuit domain of the target network, so that the whole process of voice continuity is transparent to the service network, and the continuity of the voice service of the session and the normal use of other services of the service network are ensured on the basis of not upgrading and modifying the service network.

When the target network is switched back to the source network subsequently, the whole process of switching the voice data and the IMS signaling back to the source network can be triggered by using the switching from the PS to the PS, and meanwhile, the process can also trigger the reestablishment process of other data services.

The embodiment of the invention is suitable for switching between an SAE/LTE network and a 2G/3G network, switching between an SAE/HSPA network and the 2G/3G network, and switching between a network of an IP access network supporting VoIP and a network of an IP access network not supporting VoIP.

The following describes a method, an apparatus and a system for implementing voice continuity between a single receiver IMS and a CS in a bearer level in detail through embodiments.

The first embodiment,

In this embodiment, SRV handover between a network of an IP access network supporting VoIP and a 2G/3G network is described as an example.

When the UE is in the process of network attachment or bearer establishment, the UE reports the SRV capability to the core network, or the SRV capability of the UE can be statically configured in the HSS.

When both UE and network support the process of initiating bearer establishment from the network side, UE initiates an IMS voice session in the network and triggers establishment of a dedicated voice bearer, the core network determines that the voice session is an SRV session according to the SRV capability of the UE, and notifies the wireless side, which may need to send a measurement control message to the UE, where the measurement control message may include: the method comprises the steps of supporting a PS domain and CS domain neighbor cell list, only supporting the PS domain neighbor cell list and only supporting the CS domain neighbor cell list; after the UE performs corresponding measurement, the UE sends a measurement report to the wireless side, and can perform switching between an IMS signaling bearer and an IMS voice bearer by the following three methods:

the first method is to judge whether the target network can support VoIP voice service.

If the target network can bear the VoIP voice service, the IMS signaling bearer and the IMS voice data bearer are transferred to a PS domain of the target network;

if the target network can not bear the VoIP voice service, the IMS signaling bearer is transferred to a target network PS domain, and the IMS voice data bearer is transferred to a target network CS domain;

and if the target network does not support the PS, transferring the IMS voice data bearer to the CS domain of the target network.

And secondly, pre-configuring the transfer modes of the IMS signaling bearer and the IMS voice data bearer in the source network.

The source network is statically configured to:

directly transferring IMS signaling load to a target network PS domain, and transferring IMS voice data load to a target network CS domain; or,

directly transferring the IMS signaling bearing and the IMS voice bearing to a target network PS domain; or,

and directly transferring the IMS voice data bearer to a target network CS domain, and transferring the IMS signaling data bearer to the RUA.

And the source network preferentially uses the method to transfer the IMS signaling load and the IMS voice load from the source network to the target network PS domain, judges whether the target network can support the VoIP voice service according to the feedback of the target network, transfers the IMS signaling load to the target network PS domain and transfers the IMS voice data load to the target network CS domain if the feedback result shows that the target network can not carry the VoIP voice service.

When the UE needs to be switched back to the source network from the target network, the PS switching from the target network to the source network can be used for triggering the subsequent switching of the voice data and the IMS signaling back to the source network, and meanwhile, the PS switching process can also trigger the reestablishment of other data services.

It can be seen from the technical solution provided in this embodiment that, when the UE needs to perform handover between the source network and the target network, a technical solution for implementing SRV on a bearer level can be adopted, that is, the bearing of IMS signaling is switched to the target network PS domain, the bearing of IMS voice data is switched to the target network CS domain, or, the IMS signaling load and the IMS voice data load are switched to the PS domain of the target network, or only the IMS voice data load is switched to the target network CS domain, the IMS signaling data is transferred to the RUA, and the core network associates the corresponding IMS voice service PS domain load with the CS domain load, and the PCC architecture can be subsequently utilized to process the subsequent signaling switched from the source network to the target network, so that the whole process of SRV switching is kept transparent to the IMS network, thereby simplifying the switching process, on the basis of not upgrading and modifying the IMS network, the continuity of IMS network voice data of a user and the normal use of other services of the IMS network are ensured;

meanwhile, when the target network needs to be switched back to the source network subsequently, the PS switching from the target network to the source network can be utilized to trigger the subsequent voice data and IMS signaling to be switched back to the source network, meanwhile, the PS switching process can also trigger the reestablishment of other data services, and the target network does not need to be upgraded.

Example II,

In the present embodiment, SRV handover between SAE/LTE network and 2G/3G network is taken as an example for explanation.

When the UE is attached to the SAE/LTE network, the UE reports the SRV capability to the EPC. Meanwhile, 2G/3G adjacent cell PS/CS capability information and VoIP voice service capability information are configured on the eNodeB;

when UE initiates an IMS session in SAE/LTE network and triggers the establishment of voice special bearer, EPC judges the session is SRV session according to the SRV capability of UE and informs eNodeB;

the eNodeB may need to send a corresponding measurement control message to the UE, which may include: the cell list supports PS/CS2G/3G neighbor cells, the cell list supports only 2G/3G PS neighbor cells and the cell list supports only 2G/3G CS neighbor cells;

the UE performs measurements and sends measurement reports to the eNodeB. At this time, both IMS signaling and VoIP voice traffic are carried in SAE/LTEPS domain.

The eNodeB can make the following decision according to the measurement report and the VoIP voice service capability of the target network:

if the 2G/3G network can bear VoIP voice service, the bearing of the IMS voice data and the IMS signaling is transferred to the 2G/3G PS domain;

if the 2G/3G network can not bear the VoIP voice service, the IMS signaling load is transferred to the 2G/3G PS domain, and the IMS voice data load is transferred to the 2G/3G CS domain;

if the 2G/3G network does not support the PS domain, the IMS voice data is carried and transferred to the 2G/3G CS domain, and the IMS signaling data is carried and transferred to the RUA.

The invention will be described in detail below with reference to the accompanying drawings, which illustrate specific embodiments of the invention.

The structure for switching from SAE/LTE network to 2G/3G network described in this embodiment is shown in FIG. 5.

When UE is switched to 2G/3G network from SAE/LTE network, eNodeB judges that the obtained 2G/3G PS domain can not bear voice data service according to the measurement report and whether the 2G/3G network has the capability of bearing VoIP voice service, and eNodeB informs core network: and transferring the IMS signaling bearer to a target network PS domain through PS switching, and transferring the IMS voice bearer to a target network CS domain through PS-to-CS switching.

After receiving the switching notification, the core network simulates a DTM Handover (Dual Transfer Mode Handover) process, respectively sends corresponding switching requests to the 2G/3G PS domain and the CS domain, switches the IMS voice data bearer to the 2G/3G CS domain, and switches the IMS signaling bearer to the 2G/3G PS domain.

After the switching is completed, the MME takes the Serving/PDN SAE Gateway as MGW, and establishes a link between the Serving/PDN SAEGateway and the MSC-S/MGW with the organization. From the peer UE, the IMS user plane and signalling control plane IP addresses and ports are unchanged.

As shown in fig. 6, a schematic flow chart of switching an IMS voice service from an SAE/LTE network to a 2G/3G network in this embodiment includes the following specific steps:

when the UE is attached to the SAE/LTE network, the UE reports the SRV capability to the EPC, or the SRV capability of the UE can be statically configured in the HSS. UE initiates an IMS session in SAE/LTE network and triggers the establishment of dedicated bearer;

6-1, the EPC judges that the session may need to be switched to a 2G/3G domain from an SEA/LTE network according to the SRV capability of the UE, and informs an eNodeB that the session may need SRV switching through an MME; the eNodeB may need to send a corresponding measurement control message to the UE, where the measurement control message includes: supporting a PS/CS2G/3G neighbor cell list, only supporting a 2G/3G PS neighbor cell list, only supporting a 2G/3G CS neighbor cell list, and measuring by the UE;

6-2, the UE sends the measurement report to the eNodeB. The VoIP voice service capability of the 2G/3G adjacent cell and whether the PS/CS capability is supported are configured on the eNodeB. The eNodeB judges the switching mode of IMS voice data and IMS signaling load according to the measurement report of the UE and the VoIP voice service capability of the target network:

if the eNodeB judges that the 2G/3G PS domain can bear the IMS voice data, the eNodeB sends a switching request from the PS domain to the EPC, and switches the bearing of the IMS voice data and IMS signaling to the 2G/3G PS domain;

if the eNodeB judges that the 2G/3G PS domain can not bear the IMS voice data, the eNodeB sends a switching request from the PS domain to the CS domain to the EPC, instructs the EPC to initiate a DTM handover-like process to switch the bearing of the IMS signaling to the 2G/3G PS domain and switch the bearing of the IMS voice data to the 2G/3G CS domain; and, the context information of the relevant dedicated bearer is kept in the EPC;

if the eNodeB judges that the target network does not support PS, the eNodeB sends a switching request from a PS domain to a CS domain to an EPC, instructs the EPC to switch the IMS voice data bearer to a 2G/3G CS domain, switches the IMS signaling data bearer to an RUA, and keeps the context information of the related special bearer in the EPC;

6-3, if the eNodeB judges that the target network can not bear the IMS voice data, the eNodeB sends a switching request from PS to CS to the EPC, instructs the EPC to initiate a similar DTM Handover process, switches the bearing of IMS signaling to a 2G/3G PS domain, and switches the bearing of IMS voice data to a 2G/3G CS domain; and, context information of the relevant dedicated bearer is retained in the EPC;

6-4, after the MME receives the message of switching from PS to CS, the MME sends a message of preparing switching request to SGSN, and switches the IMS signaling load to the target network PS domain;

6-5, after the MME receives the message of switching from PS to CS, starting a basic inter-MSC handover process and switching IMS voice data to a 2G/3G CS domain. Since the MME is emulated as an anchor MSC, the MSC-S/MGW does not know to be the MME originated inter-MSC handover. When establishing the inter-office link, Serving/PDN SAE Gateway is correspondingly used as MGW;

MME sends encryption key request (IMSI: International Mobile Subscriber Identifier) to MSC-S/MGW;

6-6, MSC-S/MGW returns encryption key or 'unknown part' message to MME;

6-7, after the encryption key is determined, the MME sends the message to the MSC-S by including the message in a handover preparation request message;

6-8, SGSN returns a response message of preparing switching request to MME;

6-9, 6-10, 6-11, SAE/LTE network to 2G/3G network CS domain;

at this time, MME regards Serving/PDN SAE Gateway as MGW, and organizes and establishes the link between Serving/PDN SAE Gateway and MSC-S/MGW;

when the UE at the opposite end sees that the IP address and the port of the IMS user plane and the signaling control plane are not changed, when the downlink VoIP voice service reaches Serving/PDN SAE Gateway, the data is forwarded to MSC-S/MGW, and then the MSC-S/MGW forwards the data to the UE;

when UE sends uplink voice data to MSC-S/MGW, the data is transmitted to Serving/PDN SAE Gateway, and then the Serving/PDN SAE Gateway transmits the data to opposite terminal UE;

6-12, 6-13, MME sends a user plane preparation message to Serving/PDN SAE Gateway, and Serving/PDN SAEGateway associates corresponding IMS voice data PS bearing with CS bearing; after the processing is finished, the Serving/PDN SAEGateway returns a user plane preparation finishing message to the MME;

6-14, the MME sends a DTM Handover Command to the UE;

as can be seen from the above steps, the IMS voice data bearer has been switched to the 2G/3G CS domain by PS-to-CS handover, but in order to ensure normal use of the IMS service, the IMS signaling bearer should also be switched to the GSM PS domain by PS-to-PS handover.

As shown in fig. 7, a schematic diagram of a subsequent flow for switching an IMS voice service from an SAE/LTE network to a 2G/3G network in this embodiment includes the following specific steps:

6-15, UE accesses to target 2G/3G Network, UE sends CS switching completion message to BSC/RNC (Base station controller/Radio Network controller). At the moment, the UE stops SAE/LTE network wireless signals and turns to wireless signals of a target network;

6-16, BSC/RNC sends the switch complete message to MME through MSC-S;

6-17, 6-18, MME informs Serving/PDN SAE Gateway to activate user plane, and Serving/PDN SAE Gateway returns ISUP Answer to MME;

ISUP ANSWER indicates that if a called MS (Mobile Subscriber) goes off-hook, the called MSC sends an ANSWER (ANSWER) message back to the calling MSC, and the link between the calling and called is connected;

6-19 to 6-21, BSC/RNC sends PS switch complete message to MME through SGSN, and the PS switch process from 2G/3G network to SAE/LTE network;

6-22MME releases SAE/LTE network radio resources. At this time, the UE is switched to the 2G/3G network from the SAE/LTE network, IMS signaling is carried in a target network PS domain, an IMS signaling control channel is kept, and a PCC architecture is used for processing subsequent signaling after switching.

At this time, the IMS voice data transmission is carried over a hybrid bearer, i.e., SAE/LTE PS domain bearer from Serving SAE Gateway to PDN SAE Gateway, and GSM CS domain bearer from Serving SAE Gateway to UE. Wherein SAE/LTE PS domain bearer established according to SAE/LTE network QoS parameters is between the servingSAE Gateway and the PDN SAE Gateway;

the EPC associates PS domain bearers and CS domain bearers. The whole switching process is transparent to the IMS network, the opposite terminal UE and the target network, so that the IMS real-time voice service and the non-real-time service can normally run;

6-23 to 6-26, when the IMS session is ended, the P-CSCF receives the BYE message, and the P-CSCF informs the PCRF to release the bearing. PCRF informs SAE/LTE network to release load, MME informs 2G/3G CS domain to release corresponding CS load.

In the embodiment, the SRV switching is realized on the bearing level, and the whole switching process is transparent to the IMS network, so the IMS network does not need to be upgraded and reformed; secondly, after the SAE/LTE network is switched to the 2G/3G network, the bearing of the IMS signaling is switched to the 2G/3G PS domain, and the PCC architecture is utilized to process the subsequent signaling switched from the SAE/LTE network to the 2G/3G network, thereby simplifying the whole switching process, ensuring the continuity of other services of the IMS network, and the IMS network does not need to be modified and upgraded.

When the UE in conversation moves out of the coverage area of the 2G/3G network base station and enters the coverage area of the SAE/LTE network base station, the 2G/3G network-to-SAE/LTE PS switching process can be used for triggering the whole process of switching the IMS voice and signaling back to the SAE/LTE network. At the same time, this procedure may also trigger the reactivation procedure of other data services of the SAE/LTE network.

As shown in fig. 8, a schematic flow chart of the subsequent IMS voice service switching from the 2G/3G network to the SAE/LTE network in this embodiment includes the following specific steps:

in the normal switching process from 8-1, 8-2, 2G/3G PS domain to SAE/LTE network, BSC/RNC sends PS switching request message to SGSN;

8-3, the SGSN sends a message for preparing a subsequent switching request to the New MME;

8-4 to 8-6, the New MME sends a switching request message to the eNodeB, and the eNodeB sends a switching request response message to the NEWMME;

8-7 to 8-12, the New MME informs the Serving/PDN SAE Gateway to update the context. The notification message triggers Serving/PDN SAE Gateway to establish wireless side bearing for IMS voice service. Meanwhile, the notification message can also trigger the reactivation process of other data services of the SAE/LTE network;

8-13, performing data lossless processing.

As shown in fig. 9, a schematic flow chart of the subsequent switching of the IMS voice service from the 2G/3G network to the SAE/LTE network in this embodiment is shown, and the specific steps are as follows:

8-14 to 8-15, and when all the bearing data are established, returning a response to the SGSN. The network side informs the UE of preparing switching;

8-16 to 8-20, at this time, the UE stops the PS domain and CS domain wireless signals of the destination network, starts to connect SAE/LTE network wireless signals, and sends a switching completion message to the network to access the UE to the SAE/LTE network. At this time, the UE may release CS resources at 8-16;

8-21 to 8-23, releasing the target PS and CS domain resources, and informing the PCRF of the change of the RAT (Radio Access Technology) type;

it can be known from the above steps that when a handover from the 2G/3G network to the SAE/LTE network is required, the PS handover from the 2G/3G network to the SAE/LTE network can be utilized to trigger the subsequent handover from the 2G/3G network to the SAE/LTE network, so that the handover from the 2G/3G network to the SAE/LTE network can be realized on the basis of ensuring the continuity of the voice service without upgrading the GSM network.

It can be seen from the technical solution provided in this embodiment that, when a handover needs to be performed between an SAE/LTE network and a 2G/3G network, a technical solution for implementing SRV on a bearer level may be adopted, that is, a bearer for IMS signaling is switched to a target network PS domain, and an IMS voice data bearer is switched to a target network CS domain, or both the IMS signaling bearer and the IMS voice data bearer are switched to the target network PS domain, or only the IMS voice data bearer is switched to the target network CS domain, IMS signaling data is transferred to an RUA, and the corresponding IMS voice service PS domain bearer and CS domain bearer are associated through a core network, and then a PCC architecture may be used to process subsequent signaling switched from the SAE/LTE network to the 2G/3G network, so that the whole process of SRV handover is transparent to the IMS network, thereby simplifying the handover process, and on the basis of not upgrading and modifying the IMS network, the continuity of the IMS network voice service of the user and the normal use of other services of the IMS network are ensured;

meanwhile, when a subsequent handover from the 2G/3G network back to the SAE/LTE network is required, the PS handover from the 2G/3G network to the SAE/LTE network can be utilized to trigger the entire process of switching IMS voice and signaling back to the SAE/LTE network, so that the 2G/3G network is not required to be upgraded.

Example III,

In the present embodiment, the SRV handover between the SAE/LTE network and the 2G/3G network is also taken as an example for description.

Different from the second embodiment, in the present embodiment, according to the 2G/3G network, the eNodeB is directly configured to preferentially adopt the analog DTM handover procedure, and the IMS signaling bearer is transferred to the 2G/3G PS domain through PS handover, and the IMS voice bearer is transferred to the 2G/3G CS domain through PS to CS handover.

When UE is attached to the network, the UE reports the SRV capability to a core network or the SRV capability of the UE can be statically configured in an HSS; when UE initiates an IMS voice conversation in the network and triggers the establishment of the special bearing, the core network judges that the conversation is SRV conversation according to the SRV capacity of the UE and sends a message to inform an eNodeB.

For a 2G/3G network, the eNodeB may be configured to preferentially use analog DTM handover to transfer IMS signaling bearers to the 2G/3G PS domain via PS handover and to transfer said IMS voice bearers to the 2G/3G CS domain via PS to CS handover, and the eNodeB may need to send a corresponding measurement control message to the UE, where the measurement control message includes: and simultaneously, the UE supports the list of the adjacent cells of the PS/CS, and sends a measurement report to the wireless side after carrying out corresponding measurement.

The eNodeB indicates the EPC to initiate a DTM Handover process, namely, an IMS signaling bearer is switched to a 2G/3G PS domain, an IMS voice data bearer is switched to a 2G/3G CS domain, and context information of related special bearers is reserved in a core network;

after IMS voice data load is switched to the 2G/3G CS domain, the PCC architecture can be used for processing the subsequent signaling after the switching.

And when a handover from the 2G/3G network back to the SAE/LTE network is required, a PS handover from the 2G/3G network to the SAE/LTE network can be utilized to trigger a subsequent IMS service handover from the 2G/3G network back to SAE/LTE.

It can be seen from the technical solution provided in this embodiment that, when a handover needs to be performed between a network establishing an IP access network and a 2G/3G network, a technical solution for implementing SRV on a bearer level may be adopted, that is, a bearer of an IMS signaling is directly handed over to a PS domain of a target network through a pre-configuration of an eNodeB, an IMS voice bearer is handed over to a CS domain of the target network, and a PCC architecture may be used to process a subsequent signaling after the handover, so that the entire process of SRV handover is transparent to the IMS network, thereby simplifying the handover process, and ensuring continuity of IMS network voice data of a user and normal use of other services of the IMS network on the basis of not upgrading and modifying the IMS network; meanwhile, when a subsequent handover from the 2G/3G network to the SAE/LTE network is required, the entire process of switching IMS voice and signaling back to the SAE/LTE network can be triggered by the 2G/3G to SAE/LTE PS handover, so that the 2G/3G network does not need to be upgraded.

Example four

In the present embodiment, SRV handover between SAE/LTE network and 2G/3G network is taken as an example for explanation. Different from the second embodiment, the corresponding CS bearer is established by using the core network allocated IMRN number.

When the UE is attached to the SAE/LTE network, the UE reports the SRV capability, or the SRV capability of the UE can be statically configured in the HSS. When UE initiates an IMS session in SAE/LTE network and triggers the establishment of dedicated bearer, EPC judges the session to be SRV session according to the SRV capability of UE.

When UE is switched to 2G/3G network from SAE/LTE network, eNodeB judges whether the 2G/3G network can bear VoIP voice service according to the measurement report and 2G/3G network, if the 2G/3G PS domain obtained by judgment can not bear voice data service, eNodeB informs core network: the IMS signaling bearer is transferred to the 2G/3G PS domain.

After receiving the notice, the core network transfers the IMS signaling bearer to the 2G/3G PS domain through the switching from the SAE/LTE network to the 2G/3G PS domain, and meanwhile, the MME and the Serving/PDN SAE Gateway allocate an IMRN and bring the IMRN to the UE in a PS switching command.

The UE carries out normal PS switching according to the PS switching command, the IMS signaling data of the UE is switched into a 2G/3G PS domain, meanwhile, the UE establishes a 2G/3G CS bearer from the UE to a Serving/PDN SAE Gateway through an MME according to the IMRN number, and the Serving/PDN SAE Gateway associates the corresponding CS domain bearer with the PS domain bearer.

The subsequent steps for switching from the 2G/3G network to the SAE/LTE network are the same as in the first embodiment.

It can be seen from the technical solution provided in this embodiment that, when handover needs to be performed between an SAE/LTE network and a 2G/3G network, a technical solution for implementing SRV on a bearer level can be adopted, that is, IMS signaling bearer is transferred to a 2G/3G PS domain through PS handover, and a core network allocates an IMRN number, establishes a 2G/3G CS bearer according to the IMRN number, and associates the corresponding CS domain bearer with the PS domain bearer, so that the whole process of SRV handover is transparent to the IMS network, thereby simplifying the handover process, and ensuring continuity of IMS network voice service of a user and normal use of other services of the IMS network on the basis of no need of upgrading and modifying the IMS network;

meanwhile, when the 2G/3G network needs to be switched to the SAE/LTE network subsequently, the PS switching from the 2G/3G network to the SAE/LTE network can be utilized to trigger the whole process of switching the IMS voice and signaling back to the SAE/LTE network, so that the 2G/3G network does not need to be upgraded.

EXAMPLE five

Different from the second embodiment, in the present embodiment, the SAE/LTE network preferentially uses to transfer both the IMS signaling bearer and the IMS voice data bearer to the 2G/3G PS domain, and determines whether the 2G/3G network can support the VoIP voice service according to the feedback of the 2G/3G network;

and if the feedback result is that the 2G/3G network can not bear the VoIP voice service, transferring the IMS signaling bearer to a 2G/3G PS domain and transferring the IMS voice data bearer to the 2G/3G CS domain.

When the UE is attached to the SAE/LTE network, the UE reports the SRV capability, or the SRV capability of the UE can be statically configured in the HSS. When UE initiates an IMS session in SAE/LTE network and triggers the establishment of dedicated bearer, EPC judges the session as SRV session according to the SRV capability of UE.

The network preferably uses the transfer of both the IMS signaling bearer and the IMS voice bearer to the 2G/3G PS domain, i.e. the eNodeB initiates the handover from SAE/LTE to 2G/3G PS and transfers both the IMS signaling bearer and the IMS voice bearer to the 2G/3G PS domain. At this time, the IMS signaling bearer and the VoIP voice service bearer are in SAE/LTE PS domain.

If the 2G/3G network can not bear VoIP voice service, a message is fed back to the SAE/LTE network. The eNodeB initiates a simulation DTMhandover, IMS signaling load is transferred to a 2G/3G PS domain through PS switching, and IMS voice load is transferred to a 2G/3G CS domain through PS-to-CS switching. The eNodeB may need to send a corresponding measurement control message to the UE, where the measurement control message includes a list of neighboring cells that support both the PS domain and the CS, and the UE sends a measurement report to the radio side after performing corresponding measurement.

The eNodeB indicates the EPC to initiate a DTM Handover process, namely, the IMS signaling bearer is switched to a 2G/3G PS domain, the IMS voice data bearer is switched to a 2G/3G CS domain, and the context information of the related special bearer is kept in a core network.

And when a handover from the 2G/3G network back to the SAE/LTE network is required, a PS handover from the 2G/3G network to the SAE/LTE network can be utilized to trigger a subsequent handover from the IMS service back to the SAE/LTE network from the 2G/3G network.

It can be seen from the technical solution provided in this embodiment that, when a handover needs to be performed between an SAE/LTE network and a 2G/3G network, a technical solution for implementing SRV on a bearer level may be adopted, that is, an IMS signaling bearer and an IMS voice data bearer are transferred to a 2G/3G PS domain, if the 2G/3G network cannot bear a VoIP voice service in response, the IMS signaling bearer is transferred to the 2G/3G PS domain, and the IMS voice data bearer is transferred to a 2G/3G CS domain, so that the whole process of SRV handover is transparent to the IMS network, thereby simplifying the handover process, and ensuring continuity of IMS network voice service of a user and normal use of other services of the IMS network on the basis of not upgrading and modifying the IMS network;

meanwhile, when a subsequent handover from the GSM network to the SAE/LTE network is required, the PS handover from the 2G/3G network to the SAE/LTE network can be utilized to trigger the entire process of switching the IMS voice and signaling back to the SAE/LTE network, so that the 2G/3G network is not required to be upgraded.

Example six,

In the present embodiment, SRV handover between SAE/HSPA network and 2G/3G network is taken as an example.

The difference from the second embodiment is that LTE (Long Term Evolution) in the second embodiment uses SAE (System Architecture Evolution) core network, and HSPA (high speed Packet Access) in the present embodiment uses SAE core network (i.e. SAE/HSPA).

The HSPA technology is a natural upgrade of WCDMA (Wideband Code Division Multiple Access), and has a main advantage of improving uplink and downlink data transmission rate, which is beneficial for operators to develop mobile broadband data services.

The steps of switching between the SAE/HSPA network and the 2G/3G network in this embodiment are the same as the steps of switching between the SAE/LTE network and the 2G/3G network in the second embodiment, except that in this embodiment, Evolved HSPA Access (Evolved HSPA Access) is used as the eNodeB in the second embodiment.

FIG. 10 is a diagram illustrating the UE initiating a call in the SAE/HSPA network according to this embodiment. When the HSPA uses the SAE core network (i.e., SAE/HSPA), the UE is attached in the SAE/HSPA network, and reports the SRV and NW _ Init capabilities (network initiation, capability of network initiated bearer establishment) to the EPC.

When UE initiates an IMS session in SAE/HSPA network and triggers the establishment of dedicated bearer, EPC judges the session is SRV according to the SRV capability of UE and the corresponding RAT type, and sends a message to inform the Evolved HSPA Access.

The Evolved HSPA Access may need to send a corresponding measurement control message to the UE, and the UE sends a measurement report to the Evolved HSPA Access after performing corresponding measurement.

The capability information of PS domain and CS domain of 2G/3G adjacent cell and VoIP voice service capability message can be configured on the Evolved HSPA Access.

The evaluated HSPA Access makes the following judgment according to the measurement report and the VoIP voice service capability of the 2G/3G network:

if the 2G/3G network can bear the VoIP voice service, the bearing of IMS voice data and IMS signaling is transferred to the 2G/3G PS domain;

When UE is switched to 2G/3G network from SAE/HSPA network, according to the measurement report and the ability of 2G/3G network to support VoIP voice service, if the 2G/3G PS domain is judged to be unable to bear voice data service, eNodeB informs the core network: and transferring the IMS signaling bearer to a target network PS domain, and transferring the IMS voice bearer to a target network CS domain.

After receiving the notification, the core network simulates a DTM switching process, respectively sends corresponding switching requests to the 2G/3G PS domain and the CS domain, switches the IMS voice data bearer to the 2G/3G CS domain, and switches the IMS signaling bearer to the 2G/3G PS domain.

At this time, the IMS signaling bearer and the VoIP voice bearer both use corresponding PS bearers in the SAE/HSPA network.

FIG. 11 is a schematic diagram of the SAE/HSPA handover to a 2G/3G network according to this embodiment.

When a handover from the 2G/3G network back to the SAE/HSPA network is required, a 2G/3G PS domain to SAE/HSPA network handover can be utilized to trigger a subsequent handover from the 2G/3G network to the SAE/HSPA network.

It can be seen from the technical solution provided in this embodiment that, when switching between SAE/HSPA network and 2G/3G network is required, a technical solution for implementing SRV on a bearer level may be adopted, that is, if it is determined that the 2G/3G PS domain cannot bear voice data service according to the measurement report and the capability of the 2G/3G network to support VoIP voice service, the IMS signaling bearer is transferred to the target network PS domain, and the IMS voice bearer is transferred to the target network CS domain, so that the whole process of SRV switching is transparent to the IMS network, simplifying the switching process, and ensuring continuity of IMS network voice service of the user and normal use of other services of the IMS network on the basis of no need of upgrading and modifying the IMS network;

meanwhile, when the 2G/3G network needs to be switched to the SAE/HSPA network subsequently, the PS switching from the 2G/3G network to the SAE/HSPA network can be utilized to trigger the whole process of switching the IMS voice and signaling back to the SAE/HSPA network, so that the 2G/3G network does not need to be upgraded.

EXAMPLE seven

In the present embodiment, like the sixth embodiment, SRV handover between the SAE/HSPA network and the 2G/3G network is taken as an example for explanation.

In the sixth embodiment, the Evolved HSPA Access determines how to switch according to the measurement report of the UE and whether the target network supports VoIP capability, and in this embodiment, the SAE/HSPA network preferentially uses to transfer both the IMS signaling bearer and the IMS voice bearer to the 2G/3G PS domain, determines whether the 2G/3G network can support VoIP voice service according to the feedback message of the 2G/3G network, and transfers the IMS signaling bearer to the 2G/3G PS domain and transfers the IMS voice data bearer to the 2G/3G CS domain if the feedback result is that the 2G/3G network cannot support VoIP voice service.

And when the UE is attached to the HSPA network or the bearer is established, the UE reports the SRV and NW _ Init capabilities. When UE initiates an IMS session in HSPA network and triggers the establishment of special bearing, the core network judges the session as SRV session according to the SRV capability of UE.

The SAE/HSPA network preferentially uses to transfer the IMS signaling bearer and the IMS voice bearer to the 2G/3G PS domain, namely the eNodeB initiates the switching from the SAE/HSPA network to the 2G/3G PS domain and transfers the IMS signaling bearer and the IMS voice bearer to the 2G/3G PS domain. At this time, the IMS signaling bearer and the VoIP voice service bearer are in SAE/HSPA PS domain.

If the 2G/3G network can not bear VoIP voice service and feeds back to SAE/HSPA network, the Evolved HSPA Access initiates a simulation DTM handover, IMS signaling bearing is transferred to the 2G/3G PS domain through PS switching, and IMS voice bearing is transferred to the 2G/3G CS domain through PS-to-CS switching.

The eNodeB may need to send a corresponding measurement control message to the UE, where the measurement control message includes: and simultaneously, the UE supports the list of the adjacent cells of the PS/CS, performs corresponding measurement and sends a measurement report to the wireless side.

The Evolved HSPA Access indicates EPC to initiate a DTM Handover process, IMS signaling bearer is switched to a 2G/3G PS domain, IMS voice data bearer is switched to a 2G/3G CS domain, and context information of related special bearer is reserved in a core network;

and when the switching from the 2G/3G network back to the SAE/HSPA network is needed, the PS switching from the 2G/3G network to the SAE/HSPA network can be utilized to trigger the subsequent IMS service to be switched from the 2G/3G network back to the SAE/HSPA network.

The subsequent steps for switching from the 2G/3G network to the SAE/HSPA network are the same as in the sixth embodiment.

It can be seen from the technical solution provided in this embodiment that, when switching between SAE/HSPA network and 2G/3G network is required, a technical solution of implementing SRV on a bearer level can be adopted, so that the whole process of SRV switching is kept transparent to IMS network, thereby simplifying the switching process, and ensuring continuity of IMS network voice service of a user and normal use of other services of IMS network on the basis of no need of upgrading and modifying IMS network; meanwhile, when the 2G/3G network needs to be switched to the SAE/HSPA network subsequently, the PS switching from the 2G/3G network to the SAE/HSPA network can be utilized to trigger the whole process of switching the IMS voice and signaling back to the SAE/HSPA network, so that the 2G/3G network does not need to be upgraded.

Example eight,

In this embodiment, SRV handover between SAE/HSPA network and 2G/3G network is taken as an example.

In the sixth embodiment, the HSPA uses SAE as a core network, while in the present embodiment, the HSPA uses SGSN and Serving/PDN SAEGateway core networks or SGSN and GGSN core networks.

There is an 'E' interface between SGSN and MSC-S/MGW to make it able to exchange data with 2G/3G network; and in this embodiment the SGSN acts as the MME and Serving/PDN SAE Gateway in embodiment two.

And when the UE is attached to the SAE/HSPA network, the UE reports the SRV and NW _ Init capabilities to the core network. When the UE initiates an IMS voice session in the SAE/HSPA network and triggers the establishment of a dedicated bearer, the core network judges that the voice session is an SRV session according to the SRV capability of the UE and the corresponding RAT type, and sends a message to inform an Evolved HSPA Access, wherein the Evolved HSPA Access may send a corresponding measurement control message to the UE, and the UE performs corresponding measurement and sends a measurement report to the Evolved HSPA Access;

and configuring PS/CS capability information and VoIP capability information of the 2G/3G adjacent cell on the Evolved HSPA Access.

The Evolved HSPA Access makes the following judgment according to the measurement report and the VoIP voice service supporting capability of the target network:

and if the 2G/3G network does not support the PS, transferring the IMS voice data bearer to the 2G/3G CS domain.

When the UE is switched to the 2G/3G network from the SAE/HSPA network, judging whether the obtained 2G/3G PS domain can not bear the voice data service according to the measurement report and whether the 2G/3G network can bear the VoIP voice service, and informing a core network by the eNodeB: and transferring IMS signaling load to a 2G/3G PS domain, and transferring IMS voice load to a 2G/3G CS domain.

After receiving the notification, the core network simulates a DTM switching process, respectively sends corresponding switching requests to the 2G/3G PS domain and the CS domain, switches the IMS voice data bearer to the 2G/3G CS domain, and switches the IMS signaling bearer to the 2G/3GPS domain.

After the switching is completed, SGSN is taken as MSC-S/MGW, and the organization establishes a link between SGSN and MSC-S/MGW. The opposite terminal UE and the IMS network are transparent to the whole handover process, i.e. from the opposite terminal UE, the IP addresses and ports of the IMS user plane and the signaling control plane are not changed, and the subsequent signaling after handover can be processed through the PCC architecture.

When a handover from the 2G/3G network back to the SAE/HSPA network is required, a subsequent handover from the 2G/3G CS domain back to the SAE/HSPA network is triggered by a handover from the 2G/3G PS domain to the SAE/HSPA network.

The BSC/RNC sends a PS switching request message to the SGSN, wherein the request message comprises a context of a primary PDP (packet data Protocol) bearing IMS signaling and a context of a secondary PDP bearing voice, the SGSN sends a corresponding switching request message to the Evolved HSPA Access to request switching, and the Evolved HSPA Access establishes corresponding wireless resources.

It can be seen from the technical solution provided in this embodiment that, when a handover needs to be performed between an SAE/HSPA network and a 2G/3G network, a technical solution for implementing SRV on a bearer level may be adopted, that is, a bearer of an IMS signaling is switched to a packet domain of a target network, and an IMS voice bearer is switched to a circuit domain of the target network, and a PCC architecture is used to process a subsequent signaling switched from the SAE/HSPA network to the 2G/3G CS domain, so that the whole process of SRV handover is transparent to the IMS network, thereby simplifying the handover process, and ensuring continuity of an IMS network voice service of a user and normal use of other services of the IMS network on the basis of not upgrading and modifying the IMS network; meanwhile, when switching from the 2G/3G network to the SAE/HSPA network is required subsequently, switching from the 2G/3G PS domain to the SAE/HSPA network can be utilized to trigger the subsequent switching from the 2G/3G CS domain to the SAE/HSPA network, so that the 2G/3G network is not required to be upgraded.

Examples nine,

Different from the second embodiment, in this embodiment, when the IMS voice bearer is transferred to the 2G/3GCS domain through PS to CS handover, a new network element SRV MGW (Single Radio VCC MGW, voice continuity media Gateway between the Single receiver IMS and the CS) is added to process the IMS voice bearer, that is, the spring/PDN SAE Gateway transfers IMS voice data to the SRV MGW, and the SRV MGW is responsible for voice codec conversion of the IMS voice data and associates the PS bearer and the CS bearer of the SAE/LTE. The interface between SRV MGW and MME is Mc interface and S1-MME, and the interface between SRV MGW and Serving SAEGateway is S1-U interface.

Fig. 12 is a schematic flow chart illustrating the switching of the IMS voice service from the SAE/LTE network to the 2G/3G network according to this embodiment. In step 12-11, MME informs SRV MGW to prepare corresponding CS resource and to establish inter-office bearer.

In step 12-13, the MME informs the spring/PDN SAE Gateway to transfer IMS voice data to the SRV MGW. The SRV MGW is responsible for processing IMS voice load and associating PS load and CS load of SAE/LTE, and the SRV MGW is responsible for converting voice coding and decoding of IMS voice data.

The other subsequent steps are the same as in example two.

It can be seen from the technical solution provided in this embodiment that, when a handover needs to be performed between an SAE/LTE network and a 2G/3G network, a technical solution for implementing SRV on a bearer level may be adopted, that is, a bearer for IMS signaling is switched to a target network PS domain, and an IMS voice data bearer is switched to a target network CS domain, or both the IMS signaling bearer and the IMS voice data bearer are switched to the target network PS domain, or only the IMS voice data bearer is switched to the target network CS domain, IMS signaling data is transferred to an RUA, and the corresponding IMS voice service PS domain bearer and CS domain bearer are associated through a core network, and a PCC architecture may be subsequently used to process subsequent signaling switched from the SAE/LTE network to the 2G/3G network, so that the whole process of SRV handover is transparent to the IMS network, thereby simplifying the handover process, and on the basis of not upgrading and modifying the IMS network, the continuity of the IMS network voice service of the user and the normal use of other services of the IMS network are ensured;

Example ten

In the fifth embodiment, the Evolved HSPA Access determines how to switch according to the measurement report of the UE and whether the target network supports the VoIP voice service capability, and in this embodiment, the SAE/HSPA network preferentially uses to transfer both the IMS signaling bearer and the IMS voice bearer to the 2G/3G PS domain, and determines whether the 2G/3G network can support the VoIP voice service according to the feedback of the 2G/3G network, and if the feedback result is that the 2G/3G network cannot support the VoIP voice service, transfers the IMS signaling bearer to the 2G/3G PS domain, and transfers the IMS voice data bearer to the 2G/3G CS domain.

When SAE/HSPA network is attached or a bearer is established, the UE reports SRV and NW _ Init capabilities. When the UE initiates an IMS session in SAE/HSPA network and triggers the establishment of the special bearer, the core network judges the session as an SRV session according to the SRV capability of the UE.

The SAE/HSPA network preferentially uses to transfer the IMS signaling bearer and the IMS voice bearer to the 2G/3G PS domain, namely the eNodeB initiates the switching from the SAE/HSPA to the 2G/3G PS domain and transfers the IMS signaling bearer and the IMS voice bearer to the 2G/3GPS domain. At this time, the IMS signaling bearer and the VoIP voice bearer are in the SAE/HSPA PS domain.

If the 2G/3G network can not bear VoIP voice service, and feeds back to the SAE/HSPA network. And the Evolved HSPAAccess initiates a simulation DTM handover, IMS signaling load is transferred to a 2G/3G PS domain through PS switching, and IMS voice load is transferred to a 2G/3G CS domain through switching from the PS to the CS. The eNodeB may need to send a corresponding measurement control message to the UE, where the measurement control message includes: and simultaneously, the UE supports the list of the adjacent cells of the PS/CS, performs corresponding measurement and sends a measurement report to the wireless side.

The Evolved HSPA Access indicates an EPC to initiate a DTM Handover process, the IMS signaling bearer is switched to a 2G/3G PS domain, the IMS voice data bearer is switched to a 2G/3G CS domain, and context information of related special bearer is reserved in a core network;

and after the IMS voice data bearer is switched to the 2G/3G CS domain, processing subsequent signaling after switching by utilizing a PCC architecture.

And when a switch back from the 2G/3G network to the SAE/HSPA network is required, a PS switch from the 2G/3G to the SAE/HSPA can be utilized to trigger a subsequent switch back from the IMS traffic to the SAE/HSPA from the 2G/3G network.

It can be seen from the technical solution provided in this embodiment that, when a handover needs to be performed between an SAE/HSPA network and a 2G/3G network, a technical solution for implementing SRV on a bearer level may be adopted, that is, a bearer of an IMS signaling is switched to a packet domain of a target network, and an IMS voice bearer is switched to a circuit domain of the target network, and a PCC architecture is used to process a subsequent signaling switched from the SAE/HSPA network to the 2G/3G CS domain, so that the whole process of SRV handover is transparent to the IMS network, thereby simplifying the handover process, and ensuring continuity of an IMS network voice service of a user and normal use of other services of the IMS network on the basis of not upgrading and modifying the IMS network; meanwhile, when a subsequent handover from the GSM network to the SAE/HSPA network is required, the entire process of switching the IMS voice and signaling back to the SAE/LTE network can be triggered by a PS handover from the 2G/3G to the SAE/HSPA network, so that the 2G/3G network is not required to be upgraded.

EXAMPLE eleven

In this embodiment, when the IMS voice bearer is transferred to the 2G/3G CS domain by PS to CS handover, a new network element SRV MGW is added to process the IMS voice bearer, that is, the spring/PDN SAE Gateway transfers IMS voice data to SRVMGW, and the SRV MGW is responsible for voice codec conversion of the IMS voice data and associates the PS bearer and the CS bearer of SAE/LTE. The IMS signaling is transferred to the RUA.

The interface between SRV MGW and MME is Mc interface and S1-MME, and the interface between SRV MGW and Serving SAE Gateway is S1-U interface.

As shown in fig. 13 and 14, a flowchart for switching an IMS voice service from an SAE/LTE network to a 2G/3G network according to an embodiment of the present invention includes the following specific steps:

when UE is switched to 2G/3G network from SAE/LTE network, eNodeB judges that the obtained target 2G/3G PS domain can not support packet domain service according to the measurement report and whether the 2G/3G network has the capability of bearing VoIP voice service, and eNodeB informs core network: and transferring the signaling load of the IMS session to the RUA, and transferring the IMS voice load to the CS domain of the target network through the PS-to-CS switching.

After receiving the switching notice, the core network sends a corresponding switching request to the CS domain, switches the IMS voice data to the 2G/3GCS domain, and transfers the signaling bearer of the IMS session to the RUA.

After the switching is finished, signaling data of an IMS session is transferred to the RUA, and the RUA proxies the function of the UE in an IMS domain so as to keep the registration and session state of the UE in the IMS network; Serving/PDN SAE Gateway forwards IMS voice data to SRVMGW and IMS signaling data to RAU. SRV MGW organization establishes the link between SRV MGW and MSC-S/MGW. From the peer UE, the IMS user plane and signalling control plane IP addresses and ports are unchanged.

It can be seen from the technical solution provided in this embodiment that, when a handover needs to be performed between an SAE/LTE network and a 2G/3G network, a technical solution for implementing SRV on a bearer level may be adopted, that is, a bearer for IMS signaling is switched to a target network PS domain, and an IMS voice data bearer is switched to a target network CS domain, or both the IMS signaling bearer and the IMS voice data bearer are switched to the target network PS domain, or only the IMS voice data bearer is switched to the target network CS domain, IMS signaling data is transferred to an RUA, and the corresponding IMS voice service PS domain bearer and CS domain bearer are associated through a core network, and a PCC architecture may be subsequently used to process subsequent signaling switched from the SAE/LTE network to the 2G/3G network, so that the whole process of SRV handover is transparent to the IMS network, thereby simplifying the handover process, and on the basis of not upgrading and modifying the IMS network, the continuity of the IMS network voice service of the user and the normal use of other services of the IMS network are ensured.

In order to implement SRV handover of a UE between a source network and a target network by the method in the foregoing embodiment, a base station may be used in an embodiment of the present invention, and includes:

the processing module is used for transferring the signaling bearer of the session to a PS domain of a target network when the session needs to be switched from a source network to the target network; and transferring the voice data bearer of the session to the CS domain of the target network.

In order to implement SRV handover of a UE between a source network and a target network by the method in the foregoing embodiment, an embodiment of the present invention further provides an apparatus for implementing voice continuity of a session, including:

The device may further include a second determining module, configured to determine whether the target network can carry the VoIP voice service.

If it is determined that the target network can carry VoIP voice traffic,

the processing module transfers the signaling load bearing of the session and the voice data load bearing of the session to the message of the target network PS domain;

if it is determined that the target network cannot carry VoIP voice traffic,

and the processing module is used for carrying and transferring the voice data of the session to the message of the CS domain of the target network.

The device provided by the embodiment can be seen that when switching between a source network and a target network is required, a wireless side performs a mode of switching session signaling and speech voice data according to the measurement report of the UE and the VoIP voice service capability of the target network, so that the whole switching process is transparent to the network on the basis of ensuring the voice service continuity of a user, and the network does not need to be upgraded and modified.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A method for enabling voice continuity for a conversation, comprising the steps of:

wherein the switching process is as follows:

if the target network supports VoIP voice service, transferring the signaling bearer of the session and the voice data bearer of the session to a PS domain of the target network;

if the target network does not support VoIP voice service, transferring the signaling bearer of the session to a PS domain of the target network, and transferring the voice data bearer of the session to a CS domain of the target network;

if the target network does not support the PS domain, the voice data bearer of the session is transferred to the CS domain of the target network, and the signaling bearer of the session is transferred to the remote user agent.

2. The method of claim 1, wherein the step of transferring the signaling bearer of the session to the target network PS domain comprises:

transferring signaling bearers of the session to the target network PS domain using PS to PS handover.

3. The method according to claim 1, wherein the step of transferring the voice data bearer of the session to the CS domain of the target network specifically comprises:

transferring a voice data bearer of the session to a CS domain of the target network using a PS-to-CS handover; or, in the process of transferring the signaling bearer of the session to the target network PS domain, the source network allocates a routing number;

establishing CS domain load bearing to the target network according to the routing number;

and associating the PS domain bearing with the CS domain bearing according to the routing number.

4. A method for enabling voice continuity for a conversation, comprising the steps of:

the specific switching process is as follows:

5. The method of claim 4, further comprising, before the step of:

and configuring whether the target network supports VoIP voice service transmission by using IP on the network side.

6. A method for enabling voice continuity for a conversation, comprising the steps of:

if the IMS session applied by the IP multimedia service subsystem is a session needing to keep voice continuity, when the IMS session needs to be switched from a source network to a target network;

the specific switching process is as follows:

if the target network supports VoIP voice service, transferring the signaling bearer of the IMS session and the voice data bearer of the IMS session to a PS domain of the target network;

if the target network does not support VoIP voice service, transferring the signaling bearer of the IMS session to a target network PS domain, and transferring the voice data bearer of the IMS session to a target network CS domain;

if the target network does not support the PS domain, transferring the voice data bearer of the IMS session to the CS domain of the target network, and transferring the signaling bearer of the IMS session to a remote user agent.

7. The method of claim 6, wherein the step of transferring the signaling bearer of the IMS session to the remote user agent comprises:

if the remote user agent is attached to the MME entity, the MME informs the Serving Gateway to transfer the signaling data of the IMS session to the remote user agent functional entity in the MME;

the remote user agent proxies the UE functionality in the IMS domain to maintain the UE registration and session state in the IMS network.

8. The method according to claim 6, wherein the step of transferring the voice data bearer of the IMS session to the CS domain of the target network specifically comprises:

transferring a voice data bearer of the IMS session to a CS domain of the target network using a PS to CS handover; or,

in the process of transferring the signaling bearer of the IMS session to the PS domain of the target network, a source network distributes a routing number;

9. A base station, characterized in that the base station comprises:

the judging module is used for judging that the conversation needs to be switched according to the measurement report;

a processing module, configured to transfer, when the session needs to be switched from a source network to a target network, both a signaling bearer of the session and a voice data bearer of the session to a PS domain of the target network if the target network supports a VoIP voice service; if the target network does not support VoIP voice service, transferring the signaling bearer of the session to a PS domain of the target network, and transferring the voice data bearer of the session to a CS domain of the target network; if the target network does not support the PS domain, the voice data bearer of the session is transferred to the CS domain of the target network, and the signaling bearer of the session is transferred to the remote user agent.