WO2008125067A1

WO2008125067A1 - A method and device for realizing the voice continuity of session

Info

Publication number: WO2008125067A1
Application number: PCT/CN2008/070746
Authority: WO
Inventors: Xiaobo Wu; Patrice Hede; Jian Zhang; Yungui Wang
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2007-04-17
Filing date: 2008-04-17
Publication date: 2008-10-23

Abstract

A method and device for realizing the voice continuity of session are disclosed. Said method includes: when the handover between source network and destination network is needed to perform, the technology scheme, which realizes the voice continuity on the bearer level, is adopted; if the packet domain of destination network does not support VoIP, the signaling bearer of session is switched to the packet domain of destination network, the voice bearer of session is switched to the circuit domain of destination network, and the following signaling, which is transferred from source network to the circuit domain of destination network, is processed by employing PCC architecture; the voice continuity is transparent for service network during the whole procedure. Said method guarantees both the voice service continuity of session and the normal using of other services in service network without upgrading and rebuilding the service network. When the handover from destination network to source network needs to be performed, by employing the PS handover from destination network to source network, said method triggers the handover which switches the voice data and signaling of following session to the source network.

Description

Method and device for realizing speech continuity of conversation

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

With the development of SAE/LTE (System Architecture Evolution/Long Term Evolution) network technology, SAE/LTE networks have covered some urban areas and traffic hotspots, resulting in SAE in current communication networks. /LTE network and 2G/3G (2rd Generation/3rd Generation, second generation mobile communication technology/third generation mobile communication technology) network coexist. The user who initiates the call may cross the two networks during a call. To ensure that the call is not interrupted, the switch between the SAE/LTE network and the 2G/3G network is required.

As a packet switching system, the SAE/LTE network can only carry voice transmissions on the PS (Packet Service) domain. In the SAE/LTE network, the BIS (IP Multimedia Subsystem) controls the voice service through an IP (Internet Protocol)-based network. Therefore, the voice service is generally referred to as VoIP in the SAE/LTE network. (Voice over IP, voice over IP) voice service, and in 2G/3G networks, due to lack of support for VoIP voice services, voice services are generally carried in CS TDM (Circuit System Time Division Multiplexing, circuit domain). Time division multiplexing).

After years of development, 2G/3G networks can be seen as a comprehensive coverage to some extent, due to the differences in deployment between SAE/LTE networks and 2G/3G networks, plus in different networks, mobile communications. The service bearer mechanism is different. When the UE (User Equipment) moves out of the coverage of the SAE/LTE network base station and enters the 2G/3G network base station coverage area, if the UE has an MS voice service carried on the SAE/LTE network. When the B1S voice service is interrupted, the continuity of the voice service of the user may be affected.

In order to solve the above problem and ensure the continuity of the voice service of the user, the SRV (Single Radio Voice Call Continuity between IMS and CS) technology solution is adopted, and the technical solution solves the problem of carrying the bearer in SAE/LTE. MS voice over the network and the problem of voice continuity between CS TDMs.

The premise of the SRV technical solution is that the terminal cannot receive and transmit data simultaneously in the SAE/LTE network and the 2G/3G network or other 3GPP networks.

The SRV scheme is based on inter-MSC handover (inter-MSC handover), MME (Mobility) in SAE/LTE networks. The Management Entity Mobility Management Entity is emulated as an MSC (Mobile Switch Center). There is an "E" interface between the MME and the MSC to simulate the handover between MSCs, thus the SAE/LTE network. Provides an interface for exchange of data with a 2G/3G network.

Figure 1 is a schematic diagram of a UE in an SAE/LTE network. In the figure, the UE obtains an IP connection through the SAE/LTE network and registers with the B1S network. The UE has a top S voice call. At this time, the top S signaling and the VoIP voice service are both Hosted in the SAE/LTE PS domain.

When the UE enters the 2G/3G network from the SAE/LTE network, the VoIP voice service bearer can be transferred to the 2G/3G CS domain through the switching from the PS domain to the CS (Circuit Service) domain, and the Serving/PDN SAE Gateway (Service/Packet Data Network System Evolution Network Gateway) acts as the endpoint of SIP (Session Initiation Protocol) signaling and data. At the same time, in order to maintain the SIP session, P-CSCF (Proxy-Call Session Control Function) , the proxy call session controller) must perform SIP registration (ie, register with the MS) as a UE proxy.

After switching from the SAE/LTE network to the 2G/3G CS domain, the Serving/PDN SAE Gateway also needs to have the ISUP (ISDN User Part) signaling capability to convert the SIP signaling into the corresponding content; In the subsequent handover from the 2G/3G CS domain back to the SAE/LTE network, since the base station and the MSC cannot perform the handover from the CS domain to the PS domain, the 2G/3G network needs to be upgraded to switch back from the 2G/3G network. SAE/LTE network. As shown in FIG. 2, it is a schematic diagram of switching an existing UE from a SAE/LTE network to a 2G/3G network.

The GSM (Global System for Mobile Communications) network in the 2G network is used as an example to illustrate the handover process between the SAE/LET network and the GSM network.

Figure 3 shows the flow chart of switching from the SAE/LTE network to the GSM network. The specific steps are as follows: 3-1. There is a top S voice session in the 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, the eNodeB (the base station of the SAE/LTE system) is notified by the PCRF (Policy and Charging Rules Function). The session may require a VCCXVoice Call Continuity) switch;

The top S voice session is performed between the UE and the Serving/PDN SAE Gateway/MGW, and the VoIP voice service data is transmitted on the RTP (Real Time Transport Protocol) stream;

After the eNodeB receives the notification of the MME handover, the related neighboring GSM cell is sent to the UE through the "neighbor cell list", and then the UE reports the measurement report to the eNodeB;

3-3, the eNodeB determines, according to the received UE measurement report, which GSM CS domain is switched from the SAE/LTE network, and the eNodeB sends a request message for switching from the SAE/LTE network to the GSM CS domain to 匪 E;

3-4. After receiving the handover message, the MME initiates a basic inter-MSC handover (inter-MSC handover); Since the MME is to emulate an anchor MSC, so MSC-S / MGW (Mobile Switch Center-Server / Media Gateway, a mobile switching center server / media gateway) does not know the MME is initiated inter-MSC handover ₀ in the establishment of MSC- When the S/MGW and the Serving/PDN SAE Gateway inter-office link, the Serving/PDN SAE Gateway is treated as the MGW accordingly;

3-5. The MME sends an encryption key request to the MSC-S/MGW (top SI: International Mobile Subscriber)

Identifier, International Mobile User Identifier).

3-6. The MSC-S/MGW returns a response to the MME, and the response message includes an encryption key or an "unknown portion"; 3-7. After the encryption key is determined, the MME carries the encryption key in the preparation handover request message. Sent to MSC-S;

3-8, 3-9, 3-10, normal CS handover processing flow; GSM BSC (Base Station Controller) and MSC-S (Mobile Switching Center Server) do not know that this is a special PS domain Switching to the CS domain, thus performing CS domain switching as a normal CS domain handover process;

3-11, 3-12, the MME regards the Serving/PDN SAE Gateway as an MGW, and establishes a link between the Serving/PDN SAE Gateway and the MSC-S/MGW.

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

3-14. The UE accesses the target cell, and the UE sends a handover complete message by using the MSC-S.

3-15. The MSC-S forwards the handover complete message to the MME.

If the called MS picks up the phone, the called MSC sends an "ANSWER" message to the calling MSC, at which time the link between the calling party and the called party is connected;

3-16. The MME notifies the Serving/PDN SAE Gateway to activate the user plane and notify the PCRF;

The MME notifies the eNodeB to release the original SAE/LTE network radio resources;

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

3-17. The Serving/PDN SAE Gateway sends a link update message to the PCRF. Serving/PDN SAE

Gateway notifies the PCRF top S voice session to be terminated in the Serving/PDN SAE Gateway, and the Serving/PDN SAE Gateway informs the PCRF of the IP address and port sent by the UE related SIP signaling;

3-18, the PCRF notifies the 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 top S cannot be maintained, the P-CSCF is required to register with the top S as the UE. 3- 21. The P-CSCF sends a re-invite (command to establish a session in the initial session protocol) message to the S_CSCF, notifies the Serving/PDN SAE Gateway to assign an IP address and port, and provides the assigned IP address and port to the subsequent VoIP voice. Business data usage.

In this case, the process of the UE switching from the SAE/LTE network to the GSM network can be completed through the foregoing steps, and the voice session is switched from the SAE/LTE network to the GSM CS domain through the handover from the PS domain to the CS domain to ensure the continuity of the voice service of the user. However, in order to ensure that SIP signaling and data can be transmitted normally, the IMS network needs to be upgraded and modified, thus affecting the scope of application 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 solution can also be adopted to ensure the continuity of the voice service of the user. As shown in Figure 4, the following steps are taken for the existing subsequent handover from GSM to SAE/LTE network:

4-1, BSC (Base Stat Analyzer) sends a normal inter-MSC handover request to the MSC-S/MGW;

4-2. The MSC-S/MGW forwards the preparation for the subsequent handover request to the MME.

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

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

4-5. The MME notifies the Serving/PDN SAE Gateway to prepare the user plane;

4-6. The Serving/PDN SAE Gateway returns a preparation user plane response to the MME;

4-7, the Serving/PDN SAE Gateway sends a handover command to the BSC, and the BSC forwards the handover command to the UE; 4-8, the UE sends a handover complete message to the eNodeB, and the eNodeB forwards the handover complete message to the MME;

4-9. The MME instructs the Serving/PDN SAE Gateway to use the PS domain to transmit uplink user data and notify the PCRF.

The UE returns to the SAE/LTE network;

4-10. Release the destination CS domain resource;

4-11. The Serving/PDN SAE Gateway sends a bearer message required by the network to the UE, so that the SAE/LTE network establishes an IP bearer.

4-12. At any time after the steps 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 above steps, the user can complete the GSM network after upgrading the GSM network base station and the MSC.

The CS domain to the PS domain is switched, so as to ensure the continuity of the user voice service in the process of switching from the GSM network to the SAE/LTE network.

From the above, it can be found that the prior art has the following problems: 1) After switching from the SAE/LTE network to the GSM CS domain, the Serving/PDN SAE Gateway is used as the termination point of SIP signaling and data, and the nis network needs to be modified and upgraded accordingly;

In addition, after switching from the SAE/LTE network to the GSM CS domain, the MS network needs to be modified and upgraded accordingly.

2) After switching from the SAE/LTE network to the GSM CS domain, IP-based services in the B1S network cannot be used normally because IP data cannot be transmitted normally.

3) If the subsequent handover from the GSM network to the SAE/LTE network, the base station and the MSC in the GSM network cannot complete the handover from the CS domain to the PS domain, and the GSM network needs to be upgraded.

Summary of the invention

Embodiments of the present invention provide a method and apparatus for implementing voice continuity of a session at a bearer level.

The purpose of the embodiment of the present invention is achieved by the following technical solutions:

An embodiment of the present invention provides a method for implementing voice continuity of a session, including:

The session is a session that needs to maintain voice continuity. When the session is handed over from the source network to the target network: the signaling bearer of the session is transferred to the packet service PS domain of the target network;

Transferring the voice data bearer of the session to the circuit service CS domain of the target network.

The session is a session that needs to maintain voice continuity, and receives a measurement report sent by the terminal;

Determining, by the network side, that the session needs to be handed over from the source network to the target network according to the measurement report; transferring the voice data bearer of the session to a PS domain of the target network or a CS domain of the target network; The signaling bearer of the session is transferred to the PS domain of the target network or the signaling bearer of the session is transferred to the remote user agent.

An embodiment of the present invention provides a base station, including:

The determining module 1 is configured to determine whether the session needs to be switched;

The processing module 1 is configured to: when the determining module determines that the session needs to be switched from the source network to the target network, transfer the signaling bearer of the session to the target network PS domain, and the voice data of the session The bearer is transferred to the target network CS domain.

An embodiment of the present invention provides an apparatus for implementing voice continuity of a session, including:

The determining module 2 is configured to determine whether the session needs to be switched;

The processing module 2 is configured to: when the determining module 2 determines that the session needs to be switched from a source network to a target network And transferring the voice data bearer of the session to a PS domain of the target network or a CS domain of the target network, and transferring the signaling bearer of the session to a PS domain or a remote user agent of the target network.

It can be seen from the technical solution provided by the foregoing embodiments of the present invention that when it is required to switch between the source network and the target network, a technical solution for implementing the SRV at the bearer level may be adopted.

The embodiment of the present invention keeps the entire process of voice continuity transparent to the service network, and ensures the continuity of the voice service of the session and the normal use of other services of the service network without upgrading and modifying the service network; When the subsequent handover to the source network is required, the handover from the target network to the source network may be used to trigger the subsequent voice data and the nis signaling to be switched back to the source network. At the same time, the PS handover process may also trigger the restart of other data services. Established, and, there is no need to upgrade the target network.

BRIEF DESCRIPTION OF THE DRAWINGS

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

2 is a schematic diagram of an existing handover from a SAE/LTE network to a 2G/3G network;

FIG. 3 is a schematic diagram of a process of switching from a SAE/LTE network to a 2G/3G network;

FIG. 4 is a schematic diagram of a current process of switching from a 2G/3G network to a SAE/LTE network;

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

FIG. 6 is a flowchart of switching a top S voice service from a SAE/LTE network to a 2G/3G network according to an embodiment of the present invention; FIG. 7 is a schematic diagram of switching an IMS voice service from an SAE/LTE network to a 2G/3G network according to an embodiment of the present invention; Schematic diagram of the subsequent process;

FIG. 8 is a schematic diagram of a process of switching a B1S 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 of subsequently switching a top S voice service from a 2G/3G network to an SAE/LTE network according to an embodiment of the present invention; Schematic diagram

10 is a schematic diagram of a UE initiating a top S voice call on a SAE/HSPA network according to an embodiment of the present invention;

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

12 is a flowchart (refer to SRV MGW) for switching an IMS voice service from a SAE/LTE network to a 2G/3G network according to an embodiment of the present invention;

13 is a flowchart of switching an IMS voice service from a SAE/LTE network to a 2G/3G network according to an embodiment of the present invention (introduced into SRV MGW and Xia);

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

Mode for carrying out the invention The embodiment of the present invention is to maintain the network one (the network one can support VoIP voice services, such as LTE network or HSPA (High-Speed Packet Access) network) and network 2 (network 2 may not support VoIP voice services, for example A method of voice continuity between 2G/3G networks). In the case that the network initiates a session, the network can serve as the source network, and the network 2 can serve as the target network. Correspondingly, in the case that the network 2 initiates the session, the network 2 can serve as the source network, and the network 1 can serve as the source network. Target network.

When the UE initiates a voice call and triggers the bearer setup process from the network side, the core network determines, according to the SRV capability of the UE, that the session is an SRV session, and notifies the UE to perform corresponding measurement; The measurement report, if it is judged that the target network PS domain cannot carry the voice data, the signaling bearer is transferred to the PS domain of the target network, and the voice data signaling bearer is transferred to the target network CS domain, so that the SRV is implemented at the bearer level. The handover process is performed, and the PCC architecture is used to process the subsequent signaling after the handover.

If the target network cannot carry the VoIP voice service, the signaling bearer is transferred to the PS domain of the target network through the PS handover, and the core network allocates a B1RN number (IP Multimedia Routing Number) and sends it to the UE together with the PS handover command. The UE establishes a CS domain bearer of the target network from the UE to the core network according to the top RN number, and the core network associates the CS domain bearer with the corresponding PS domain bearer according to the top RN number.

If the target network packet domain supports VoIP voice traffic, the signaling bearer and voice bearer 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, and the voice bearer of the session is switched to the circuit domain of the target network, and the PCC architecture is used to process the subsequent letter from the source network to the target network circuit domain. Therefore, the entire 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 without upgrading and modifying the service network.

When the target network is switched back to the source network, the PS to PS switch can be used to trigger the entire process of switching voice data and nis signaling back to the source network. At the same time, this process can also trigger the re-establishment process of other data services.

The embodiments of the present invention are applicable to handover between a SAE/LTE network and a 2G/3G network, and are also applicable to handover between a SAE/HSPA network and a 2G/3G network, and are also applicable to a network of an IP access network supporting VoIP. Switching between networks of IP access networks that do not support VoIP.

In the embodiment of the present invention, if the target network packet domain does not support VoIP, the bearer of the BIS signaling is switched to the packet domain of the target network, and the B1S voice bearer is switched to the circuit domain of the target network, and the PCC (Policy and Charging) is utilized. Control, policy control and charging control) architecture to handle subsequent signaling from the source network to the target network circuit domain, so that the entire process of SRV handover is transparent to the B1S network, thereby simplifying the handover process without the need for the MS network. Based on the upgrade and transformation, the continuity of the user's MS network voice service and the MS are guaranteed. Normal use of other services of the network; meanwhile, when it is required to switch back from the target network to the source network, the PS switch from the target network to the source network may be used to trigger subsequent voice data and nis signaling to switch back to the source network, and at the same time, the PS The handover process can also trigger the re-establishment of other data services, and there is no need to upgrade the target network.

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

If the target network does not support the packet domain, then the signaling bearer of the session is switched to the RUA (Remote User Agent), and the voice bearer of the session is switched to the circuit domain of the target network, and the source is processed by the PCC architecture. The network switches to the subsequent signaling of the target network circuit domain, so that the entire process of voice continuity is transparent to the service network, and the continuity of the voice service of the session and the service network are ensured without upgrading and modifying the service network. Normal use of business

The method, apparatus and system for realizing the speech continuity between the single receivers nis and cs at the bearer level are described in detail below by way of embodiments.

Embodiment 1

In this embodiment, the SRV handover between the network supporting the VoIP IP access network and the 2G/3G network is taken as an example. When the UE attaches or bears the establishment process, 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 the UE and the network support the process of initiating bearer setup from the network side, the UE initiates a top S voice session in the network and triggers the establishment of a voice dedicated bearer. The core network determines that the voice session is an SRV session according to the SRV capability of the UE. And notifying the wireless side, the radio side may need to send a measurement control message to the UE, and the measurement control message may include: supporting a PS domain and a CS domain neighbor cell list, supporting only a PS domain neighbor cell list, and only supporting a CS domain neighbor cell list; After the UE performs the corresponding measurement, the measurement report is sent to the wireless side, and the top S signaling bearer and the top S voice bearer can be switched by the following three methods:

Method 1: Determine whether the target network can support VoIP voice services.

If the target network can carry the VoIP voice service, the top S signaling bearer and the top S voice data bearer are all transferred to the target network PS domain;

If the target network cannot carry the VoIP voice service, the top S signaling bearer is transferred to the target network PS domain, and the top S voice data bearer is transferred to the target network CS domain;

If the target network does not support PS, the nis voice data bearer is transferred to the target network cs domain. Method 2: Pre-configure the transfer mode of the nis signaling bearer and the nis voice data bearer in the source network. The source network is statically configured to: Directly transferring the nis signaling bearer to the target network PS domain, and transferring the nis voice data bearer to the target network cs domain; or

Directly transfer both the MS signaling bearer and the MS voice bearer to the target network PS domain; or

The top S voice data bearer is directly transferred to the target network CS domain, and the top S signaling data bearer is transferred to the RUA. Method 3: The source network preferentially uses the nis signaling bearer and the nis voice bearer to be transferred from the source network to the target network.

The PS domain, and according to the feedback of the target network, determines whether the target network can support the VoIP voice service. If the feedback result is that the target network cannot bear the VoIP voice service, the nis signaling bearer is transferred to the target network PS domain, and the nis voice data bearer is transferred. Go to the target network cs domain.

When the UE needs to switch back to the source network from the target network, the target network to source network PS handover may be used to trigger subsequent handover of the voice data and the nis signaling back to the source network, and the PS handover process may also trigger other data services. Re-established.

As shown in the technical solution provided by the embodiment, when the UE needs to perform the handover between the source network and the target network, the technical solution of implementing the SRV on the bearer level may be adopted, that is, the bearer of the NIS signaling is switched to the PS domain of the target network. Switching the nis voice data bearer to the target network cs domain, or switching both the nis signaling bearer and the nis voice data bearer to the target network PS domain, or only switching the nis voice data bearer to the target network cs domain, The data is transferred to the RUA, and the corresponding top S voice service PS domain bearer and the CS domain bearer are associated through the core network, and then the PCC architecture can be used to process the subsequent signaling of the source network to the target network, so that the entire SRV switchover is performed. The process is transparent to the nis network, which simplifies the handover process. On the basis of no need to upgrade and modify the nis network, the continuity of the user's top S network voice data and the normal use of other services of the top S network are ensured;

At the same time, when the UE needs to switch back to the source network from the target network, the PS switch from the target network to the source network can be used to trigger the subsequent voice data and the nis signaling to switch back to the source network. Meanwhile, the PS handover process can also trigger other data services. Re-established, and there is no need to upgrade the target network.

Embodiment 2

In this embodiment, the SRV switching between the SAE/LTE network and the 2G/3G network is taken as an example.

When the UE is attached to the SAE/LTE network, the UE reports the SRV capability to the EPC (Evolved Packet Core). At the same time, the 2G/3G neighbor cell PS/CS capability information and the VoIP voice service capability message are configured on the eNodeB;

When the UE initiates an IMS session in the SAE/LTE network and triggers the establishment of the voice dedicated bearer, the EPC determines that the session is an SRV session according to the SRV capability of the UE, and notifies the eNodeB;

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

The UE performs measurements and sends a measurement report to the eNodeB. At this time, both IMS signaling and VoIP voice services are carried in the SAE/LTE PS domain.

The eNodeB can make the following judgment according to the measurement report and the VoIP voice service capability of the target network: if the 2G/3G network can carry the VoIP voice service, transfer the bearer of the B1S voice data and the IMS signaling to the 2G/3G PS domain;

If the 2G/3G network cannot carry the VoIP voice service, the top S signaling bearer is transferred to the 2G/3G PS domain, and the top S voice data bearer is transferred to the 2G/3G CS domain;

If the 2G/3G network does not support the PS domain, the top S voice data bearer is transferred to the 2G/3G CS domain, and the IMS signaling data bearer is transferred to the RUA.

The invention will now be described in detail in conjunction with the drawings of specific embodiments of the invention.

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

When the UE switches from the SAE/LTE network to the 2G/3G network, the eNodeB determines whether the 2G/3G PS domain cannot carry the voice data service according to the measurement report and whether the 2G/3G network has the capability of carrying the VoIP voice service, and the eNodeB notifies. Core network: The nis signaling bearer is transferred to the target network PS domain through PS handover, and the nis voice bearer is transferred to the target network CS domain through PS to cs handover.

After receiving the handover notification, the core network simulates a DTM handover (Dual Transfer Mode Handover) process, and sends a corresponding handover request to the 2G/3G PS domain and the CS domain respectively, and switches the B1S voice data. To the 2G/3G CS domain, the top S signaling bearer is switched to the 2G/3G PS domain.

After the handover is completed, the MME regards the Serving/PDN SAE Gateway as the MGW and establishes Serving/PDN with its organization.

The link between the SAE Gateway and the MSC-S/MGW. From the perspective of the peer UE, the IP address and port of the top S user plane and the signaling control plane have not changed.

As shown in FIG. 6, the flow chart of the process of switching the B1S voice service from the SAE/LTE network to the 2G/3G network in this embodiment is as follows:

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. The UE initiates a B1S session in the SAE/LTE network and triggers establishment of a dedicated bearer;

Based on the SRV capability of the UE, the 6-KEPC may determine that the session may need to be handed over from the SEA/LTE network to the 2G/3G domain, and the MME may notify the eNodeB that the session may require SRV handover; the eNodeB may need to send a corresponding measurement control message to the UE. The measurement control message includes: supporting the PS/CS 2G/3G neighbor cell list, supporting only the 2G/3G PS neighbor cell list, and only supporting the 2G/3G CS neighbor cell list, and the UE performs measurement; 6-2. The UE sends a measurement report to the eNodeB. Configure the VoIP voice service capability of the 2G/3G neighboring cell on the eNodeB and whether to support the PS/CS capability. The eNodeB determines the switching mode of the MS voice data and the MS signaling bearer according to the measurement report of the UE and the VoIP voice service capability of the target network:

If the eNodeB determines that the 2G/3G PS domain can carry the MS voice data, the eNodeB sends a PS domain to PS domain handover request to the EPC, and switches the MS voice data and the MS signaling bearer to the 2G/3G PS domain. If the eNodeB determines that the 2G/3G PS domain cannot bear the MS voice data, the eNodeB sends a PS domain to the CS domain handover request to the EPC, instructing the EPC to initiate a similar DTM handover procedure to switch the bearer of the MS signaling to the 2G/3G PS domain, and Switching the B1S voice data bearer to the 2G/3G CS domain; and retaining the context information of the associated dedicated bearer in the EPC;

If the eNodeB determines that the target network does not support the PS, the eNodeB sends a PS domain to the CS domain handover request to the EPC, instructing the EPC to switch the B1S voice data bearer to the 2G/3G CS domain, and switch the B1S signaling data bearer to the RUA, and The context information of the associated dedicated bearer is retained in the EPC;

6-3. If the eNodeB determines that the target network cannot bear the MS voice data, the eNodeB sends a PS to CS handover request to the EPC, instructing the EPC to initiate a DTM Handover process, and switching the bearer of the MS signaling to the 2G/3G PS domain. Switching the B1S voice data bearer to the 2G/3G CS domain; and, the context information of the associated dedicated bearer is retained in the EPC;

6-4. After the MME receives the PS to CS handover message, the MME sends a preparation handover request message to the SGSN, and switches the IMS signaling bearer to the target network PS domain.

6-5. After receiving the PS to CS handover message, the MME starts a basic inter-MSC handover procedure, and switches the B1S voice data to the 2G/3G CS domain. Since the MME is emulated as an anchor MSC, the MSC-S/MGW does not know that it is an inter-MSC handover initiated by E. When establishing an inter-office link, the Serving/PDN SAE Gateway is treated as an MGW accordingly;

MSC-S/MGW; IMSI: International Mobile Subscriber Identifier (International Mobile Subscriber Identifier);

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

6-7, after the encryption key is determined, the MME sends the message to the MSC-S in the preparation handover request message; 6-8, the SGSN returns a preparation handover request response message to the MME;

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

At this time, the MME regards the Serving/PDN SAE Gateway as an MGW, and establishes a link between the Serving/PDN SAE Gateway and the MSC-S/MGW; The IP address and port of the MS user plane and the signaling control plane do not change. When the downlink VoIP voice service reaches the Serving/PDN SAE Gateway, the data is forwarded to the MSC-S/MGW. Then, the MSC-S /MGW forwards the data to the UE;

After the UE sends the uplink voice data data to the MSC-S/MGW, the data is forwarded to the Serving/PDN SAE Gateway, and then the Serving/PDN SAE Gateway forwards the data to the peer UE;

6-12 6-13 The MME sends a preparation user plane message to the Serving/PDN SAE Gateway. The Serving/PDN SAE Gateway associates the corresponding top S voice data PS bearer with the CS bearer. After the processing is completed, the Serving/PDN SAE Gateway returns to the user. The face preparation message is sent to the MME;

6-14, Send DTM Handover Co nd to the UE;

It can be seen from the above steps that the top S voice data bearer has been switched to the 2G/3G CS domain through the PS to CS handover, but in order to ensure the normal use of the top S service, the top S signaling bearer should also be performed through the PS to PS handover. Switch to the GSM PS domain.

As shown in FIG. 7, the following is a schematic diagram of a subsequent process for switching a B1S voice service from a SAE/LTE network to a 2G/3G network according to the following steps:

6-15 UE accesses the target 2G/3G network, and the UE sends a CS handover complete message to the BSC/RNC (Base Station Controller/Radio Network, Base Station Controller/Radio Network Controller). At this time, the UE stops the SAE/LTE network wireless signal and turns to the wireless signal of the target network;

6-16 BSC/RNC sends a handover complete message to MME through MSC-S

6-17 6-18 MME Notification Serving/PDN SAE Gateway activates the user plane, and Serving/PDN SAE Gateway returns ISUP Answer to hide;

ISUP ANSWER indicates that if the called MS (Mobile Subscriber, mobile subscriber) picks up the phone, the called party

The MSC sends an "ANSWER" message to the calling MSC, at which point the link between the calling party and the called party is connected;

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

6-22 MME releases SAE/LTE network radio resources. At this time, the UE switches from the SAE/LTE network to the 2G/3G network, the MS signaling is carried in the target network PS domain, and the top S signaling control channel is maintained, and the PCC architecture is used to process the subsequent signaling after the handover.

At this time, the B1S voice data is transmitted on the hybrid bearer, that is, the SAE/LTE PS domain bearer is from the Serving SAE Gateway to the PDN SAE Gateway, and the GSM CS domain bearer is carried between the Serving SAE Gateway and the UE. The SAE/LTE PS domain bearer established according to the SAE/LTE network QoS (Quality of Service) parameter from the Serving SAE Gateway to the PDN SAE Gateway; The EPC associates the PS domain bearer with the CS domain bearer. The entire handover process is transparent to the BIS network, the peer UE, and the destination network. Therefore, the real-time voice service and the non-real-time service can operate normally.

6-23 to 6-26. When the top S session ends, the P-CSCF receives the BYE message, and the P-CSCF notifies the PCRF to release the bearer. The PCRF notifies the SAE/LTE network to release the bearer, and the MME notifies the 2G/3G CS domain to release the corresponding CS bearer.

In this embodiment, by implementing the SRV switching at the bearer level, the entire handover process remains transparent to the B1S network, so the B1S network does not need to be upgraded and modified. Second, after switching from the SAE/LTE network to the 2G/3G network, By switching the bearer of the top S signaling to the 2G/3G PS domain, the PCC architecture is used to process the subsequent signaling from the SAE/LTE network to the 2G/3G network, simplifying the entire handover process and ensuring continuity of other services of the B1S network. Sex, and the top S network does not need to be modified and upgraded.

When the UE in the call moves out of the 2G/3G network base station coverage area and enters the coverage of the SAE/LTE network base station, the 2G/3G network to the SAE/LTE PS handover process can be used to trigger the entire top S voice and signaling. Switch back to the SAE/LTE network process. At the same time, this process can also trigger the reactivation process of other data services on the SAE/LTE network.

As shown in FIG. 8, the flow of the subsequent top S voice service from the 2G/3G network to the SAE/LTE network is shown in the following steps. The specific steps are as follows:

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

8-3. The SGSN sends a preparation for a subsequent handover request message to the New MME.

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

8-7 to 8-12, New MME informs Serving/PDN SAE Gateway to update the context. Notification message trigger

The Serving/PDN SAE Gateway establishes a radio side bearer for the top S voice service. At the same time, the notification message may also trigger a reactivation process of other data services of the SAE/LTE network;

8-13. Data lossless processing.

As shown in FIG. 9, the flow chart of the subsequent handover of the MS voice service from the 2G/3G network to the SAE/LTE network is as follows:

8-14 to 8-15. When all the bearer data is established, the response is returned to the SGSN. The network side notifies the UE to prepare for handover;

8-16 to 8-20, at this time, the UE stops the wireless signal of the destination network PS domain and the CS domain, starts to connect to the SAE/LTE network wireless signal, and the UE sends a handover complete message to the network, and connects 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 PS domain and the CS domain resource of the destination network, and notifying the PCRF RAT (Radio Access Technology) type change;

According to the above steps, when it is required to switch from the 2G/3G network to the SAE/LTE network, the 2G/3G network can be used to switch to the SAE/LTE network PS, and the subsequent handover from the 2G/3G network to the SAE/LTE network can be triggered. It is not necessary to upgrade the GSM network, but to switch from the 2G/3G network back to the SAE/LTE network on the basis of ensuring the continuity of the voice service.

As shown in the technical solution provided by the embodiment, when a handover between the SAE/LTE network and the 2G/3G network is required, the technical solution of implementing the SRV on the bearer level may be adopted, that is, the bearer of the B1S signaling is switched to the target. The internet

In the PS domain, the nis voice data bearer is switched to the target network cs domain, or both the nis signaling bearer and the nis voice data bearer are switched to the target network PS domain, or only the nis voice data bearer is switched to the target network cs domain, The nis signaling data is transferred to the RUA and the corresponding top S voice service PS domain bearer and the CS domain bearer are associated through the core network, and the subsequent PCC architecture can be used to process subsequent signaling from the SAE/LTE network to the 2G/3G network. The entire process of SRV handover is transparent to the nis network, thereby simplifying the handover process, ensuring the continuity of the user's top S network voice service and other services of the top S network without upgrading and modifying the nis network. Normal use;

At the same time, when you need to switch back to the SAE/LTE network from the 2G/3G network, you can use the 2G/3G network to

The SAE/LTE network PS handover triggers the entire process of switching the top S voice and signaling back to the SAE/LTE network, thereby eliminating the need to upgrade the 2G/3G network.

Embodiment 3

In this embodiment, the SRV switching between the SAE/LTE network and the 2G/3G network is also taken as an example.

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

When the UE is attached to the network, the UE may report the SRV capability to the core network or the SRV capability of the UE may be statically configured in the HSS; when the UE initiates a top S voice session in the network and triggers the establishment of the dedicated bearer, the core network according to the UE The SRV capability determines that the session is an SRV session and sends a message to the eNodeB.

For a 2G/3G network, the eNodeB can be configured to preferentially use the analog DTM handover, transfer the top S signaling bearer to the 2G/3G PS domain through PS handover, and transfer the top S voice bearer to 2G through PS to CS handover. In the /3G CS domain, the eNodeB may need to send a corresponding measurement control message to the UE. The measurement control message includes: a list of neighboring cells supporting the PS/CS at the same time, and the UE sends a measurement report to the wireless side after performing corresponding measurement.

The eNodeB instructs the EPC to initiate the DTM Handover process, which switches the top S signaling bearer to the 2G/3G PS domain, and the top S The voice data bearer is switched to the 2G/3G CS domain, and the context information of the associated dedicated bearer is retained in the core network. After the MS voice data bearer is switched to the 2G/3G CS domain, the PCC architecture can be used to process the subsequent call. Signaling.

When switching from the 2G/3G network to the SAE/LTE network, the PS switch from the 2G/3G network to the SAE/LTE network can be used to trigger the subsequent MS service to switch from the 2G/3G network back to SAE/LTE.

The technical solution provided by this embodiment can be used to implement the SRV technical solution at the bearer level when the switch between the network that establishes the IP access network and the 2G/3G network needs to be switched, that is, the pre-configuration by the eNodeB. The NIS signaling bearer is directly switched to the target network PS domain, and the nis voice bearer is switched to the target network cs domain, and the PCC architecture can be used to process the subsequent signaling after the handover, so that the entire process of the SRV handover is maintained for the nis network. Transparent, which simplifies the switching process. On the basis of the upgrade and modification of the top S network, the continuity of the user's top S network voice data and the normal use of other services of the B1S network are guaranteed. Meanwhile, when the subsequent needs are from 2G/ When the 3G network switches to the SAE/LTE network, the 2G/3G to SAE/LTE PS handover can be used to trigger the entire process of switching the top S voice and signaling back to the SAE/LTE network, thereby eliminating the need to upgrade the 2G/3G network. .

Embodiment 4

In this embodiment, the SRV switching between the SAE/LTE network and the 2G/3G network is taken as an example. Different from the second embodiment, the top RN number allocated by the core network is used to establish a corresponding CS bearer.

When the UE attaches 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 the UE initiates a top S session in the SAE/LTE network and triggers the establishment of the dedicated bearer, the EPC determines that the session is an SRV session according to the SRV capability of the UE.

When the UE switches from the SAE/LTE network to the 2G/3G network, the eNodeB can carry the VoIP voice service according to the measurement report and the 2G/3G network. If the 2G/3G PS domain that the judgment is determined cannot carry the voice data service, the ijeNodeB notifies. Core network: Transfer the B1S signaling bearer to the 2G/3G PS domain.

After receiving the notification, the core network transfers the MS signaling bearer to the 2G/3G PS domain through the handover of the SAE/LTE network to the 2G/3G PS domain, and the MME and the Serving/PDN SAE Gateway allocate a top RN and switch commands in the PS. Bring to the UE.

The UE performs normal PS handover according to the PS handover command, and switches the MS signaling data of the UE to the 2G/3G PS domain, and the UE establishes from the UE to the Serving/PDN SAE Gateway through the MME according to the top RN number.

The 2G/3G CS bearers, and the Serving/PDN SAE Gateway associates the corresponding CS domain bearers with the PS domain bearers.

The subsequent steps of switching from the 2G/3G network to the SAE/LTE network are the same as those in the first embodiment. As shown in the technical solution provided by the embodiment, when a handover between the SAE/LTE network and the 2G/3G network is required, the technical solution of implementing the SRV at the bearer level may be adopted, that is, the B1S signaling is carried by the PS handover. Transfer to the 2G/3G PS domain, and the core network allocates a top RN number, establishes a 2G/3G CS bearer according to the top RN number, and the core network associates the corresponding CS domain bearer with the PS domain bearer, so that the entire SRV switch The process is transparent to the B1S network, which simplifies the handover process. On the basis of the upgrade and modification of the top S network, the continuity of the user's top S network voice service and the normal use of other services of the top S network are ensured.

At the same time, when it is necessary to switch from the 2G/3G network to the SAE/LTE network, the PS switch from the 2G/3G network to the SAE/LTE network can be used to trigger the entire process of switching the top S voice and signaling back to the SAE/LTE network. This eliminates the need to upgrade 2G/3G networks.

Embodiment 5

Different from the second embodiment, in this embodiment, the SAE/LTE network preferentially transfers both the BIS signaling bearer and the BIS voice data bearer to the 2G/3G PS domain, and judges 2G according to the feedback of the 2G/3G network. Whether the /3G network can support VoIP voice services;

If the feedback result is that the 2G/3G network cannot carry the VoIP voice service, the B1S signaling bearer is transferred to the 2G/3G.

The PS domain transfers the top S voice data bearer to the 2G/3G CS domain.

The network priority uses the top S signaling bearer and the top S voice bearer to be transferred to the 2G/3G PS domain, and the BPeNodeB initiates the slave

The SAE/LTE to 2G/3G PS handover transfers both the top S signaling bearer and the top S voice bearer to the 2G/3G PS domain. At this time, the top S signaling bearer and the VoIP voice service bearer are both in the SAE/LTE PS domain.

If the 2G/3G network cannot carry the VoIP voice service, the feedback message is sent back to the SAE/LTE network. The eNodeB initiates an analog DTM handover, and transfers the top S signaling bearer to the 2G/3G PS domain through PS handover, and transfers the top S voice bearer to the 2G/3G CS domain through PS to CS handover. The eNodeB may need to send a corresponding measurement control message to the UE. The measurement control message includes a list of neighboring cells supporting both the PS domain and the CS. After the UE performs corresponding measurement, the UE sends a measurement report to the wireless side.

The eNodeB instructs the EPC to initiate the DTM Handover process to switch the top S signaling bearer to the 2G/3G PS domain, switch the top S voice data bearer to the 2G/3G CS domain, and keep the context information of the associated dedicated bearer in the core network. in.

When you need to switch back to the SAE/LTE network from the 2G/3G network, you can use the 2G/3G network to the SAE/LTE network. The PS handover triggers subsequent handover from the 2G/3G network back to the SAE/LTE network from the MS service.

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

As shown in the technical solution provided by the embodiment, when a handover between the SAE/LTE network and the 2G/3G network is required, the technical solution of implementing the SRV at the bearer level may be adopted, that is, the nis signaling bearer and the nis voice data are used. The bearer is transferred to the 2G/3G PS domain. If the 2G/3G network response cannot carry the VoIP voice service, the top S signaling bearer is transferred to the 2G/3G PS domain, and the top S voice data bearer is transferred to the 2G/3G CS domain. The entire process of SRV handover is transparent to the top S network, which simplifies the handover process. On the basis of the upgrade and modification of the top S network, the continuity of the B1S network voice service and other services of the top S network are ensured. Normal use;

At the same time, when the 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 BIS voice and signaling back to the SAE/LTE network, thereby eliminating the need for Upgrade the 2G/3G network.

Embodiment 6

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

The difference from the second embodiment is that in the second embodiment, LTE (Long Term Evolution) uses a SAE (System Architecture Evolution) core network, and in this embodiment,

HSPA (High Speed Packet Access) uses the SAE core network (gpSAE/HSPA).

HSPA technology is a natural upgrade of WCDMA (Wideband Code Division Multiple Access). Its main advantage is that it can increase the uplink and downlink data transmission rate, which is beneficial for operators to carry out mobile broadband data services.

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

FIG. 10 is a schematic diagram of a UE initiating a call on a SAE/HSPA network according to the embodiment. When HSPA uses the SAE core network (gp SAE/HSPA), the UE is attached to the SAE/HSPA network, and the UE reports the SRV and the _Init capability (Network initiation, network initiation bearer establishment capability) to the EPC.

When the UE initiates a top S session in the SAE/HSPA network and triggers the establishment of the dedicated bearer, the EPC determines the session as the SRV session according to the SRV capability of the UE and the corresponding RAT type, and sends a message to notify Evolved HSPA Access o.

The Evolved HSPA Access may need to send a corresponding measurement control message to the UE. After the UE performs the corresponding measurement, it sends a measurement report to Evolved HSPA Access. The 2G/3G neighbor cell PS domain and CS domain capability information and the VoIP voice service capability message can be configured on the Evolved HSPA Access.

Based on the measurement report and the VoIP voice service capabilities of the 2G/3G network, Evolved HSPA Access makes the following judgments:

If the 2G/3G network can carry the VoIP voice service, the bearer of the top S voice data and the top S signaling is transferred to the 2G/3G PS domain;

When the UE switches from the SAE/HSPA network to the 2G/3G network, according to the measurement report and the ability of the 2G/3G network to support the VoIP voice service, if it is determined that the 2G/3G PS domain cannot carry the voice data service, the eNodeB notifies the core network: The top S signaling bearer is transferred to the target network PS domain, and the B1S voice bearer is transferred to the target network CS domain.

After receiving the notification, the core network simulates a DTM handover process, and sends corresponding handover requests to the 2G/3G PS domain and the CS domain respectively, and switches the top S voice data to the 2G/3G CS domain, and the top S signaling. The bearer is switched to the 2G/3G PS domain.

At this time, both the IMS signaling bearer and the VoIP voice bearer are in the SAE/HSPA network, and the corresponding PS bearers are respectively used. As shown in FIG. 11, it is a schematic diagram of switching from SAE/HSPA to 2G/3G network in this embodiment.

When it is necessary to switch back to the SAE/HSPA network from the 2G/3G network, the 2G/3G PS domain can be switched to the SAE/HSPA network to trigger subsequent handover from the 2G/3G network to the SAE/HSPA network.

It can be seen from the technical solution provided by this embodiment that when a handover between the SAE/HSPA network and the 2G/3G network is required, the technical solution of implementing the SRV on the bearer level may be adopted, that is, the wireless side according to the measurement report and 2G/ The ability of the 3G network to support the VoIP voice service. If it is determined that the 2G/3G PS domain cannot carry the voice data service, the top S signaling bearer is transferred to the PS domain of the target network, and the B1S voice bearer is transferred to the target network CS domain. The entire process of SRV switching is transparent to the nis network, which simplifies the handover process. On the basis of no need to upgrade and modify the nis network, the continuity of the user's top S network voice service and the normal use of other services of the top S network are guaranteed. ;

At the same time, when it is necessary to switch from the 2G/3G network to the SAE/HSPA network, the PS switch from the 2G/3G network to the SAE/HSPA network can be used to trigger the entire process of switching the top S voice and signaling back to the SAE/HSPA network. This eliminates the need to upgrade 2G/3G networks.

Example 7 In the present embodiment, as in the sixth embodiment, the SRV switching between the SAE/HSPA network and the 2G/3G network is taken as an example.

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 the VoIP capability. In this embodiment, the SAE/HSPA network preferentially uses the B1S signaling bearer and the IMS voice bearer. All of them are transferred to the 2G/3G PS domain. According to the feedback message of the 2G/3G network, it is judged whether the 2G/3G network can support the VoIP voice service. If the feedback result is that the 2G/3G network cannot carry the VoIP voice service, the B1S signaling is performed. The bearer is transferred to the 2G/3G PS domain, and the top S voice data bearer is transferred to the 2G/3G CS domain.

When the UE attaches or bears the HSPA network, the UE reports the SRV and _Init capabilities. When the UE initiates a top S session in the HSPA network and triggers the establishment of the dedicated bearer, the core network determines that the session is an SRV session according to the SRV capability of the UE.

The SAE/HSPA network preferentially transfers both the B1S signaling bearer and the B1S voice bearer to the 2G/3G PS domain, that is, the eNodeB initiates the handover from the SAE/HSPA network to the 2G/3G PS, and transfers both the B1S signaling bearer and the B1S voice bearer. Go to the 2G/3G PS domain. At this time, the top S signaling bearer and the VoIP voice service bearer are both in the SAE/HSPA PS domain.

If the 2G/3G network cannot carry the VoIP voice service and feed back to the SAE/HSPA network, the Evolved HSPA Access initiates the analog DTM handover, and the top S signaling bearer is transferred to the 2G/3G PS domain through the PS handover, and the PS to CS handover is performed. Transfer the B1S voice bearer to the 2G/3G CS domain.

The eNodeB may need to send a corresponding measurement control message to the UE. The measurement control message includes: a list of neighboring cells supporting the PS/CS at the same time, and the UE performs corresponding measurement and sends a measurement report to the wireless side.

Evolved HSPA Access instructs the EPC to initiate the DTM Handover procedure, switching the top S signaling bearer to the 2G/3G PS domain, switching the top S voice data bearer to the 2G/3G CS domain, and the context information of the associated dedicated bearer remains in the core. In the net;

When switching from the 2G/3G network to the SAE/HSPA network, the PS switch from the 2G/3G network to the SAE/HSPA network can be used to trigger the subsequent B1S service to switch from the 2G/3G network back to the SAE/HSPA network.

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

It can be seen that the technical solution of the present embodiment provides that when a handover between the SAE/HSPA network and the 2G/3G network is required, the technical solution of implementing the SRV at the bearer level may be adopted, so that the entire process of the SRV handover is performed on the B1S network. Keeping transparent, which simplifies the switching process, ensures the continuity of the user's top S network voice service and the normal use of other services of the top S network, without the need to upgrade and modify the top S network; When the 2G/3G network is switched to the SAE/HSPA network, the PS switch from the 2G/3G network to the SAE/HSPA network can be used to trigger the entire process of switching the top S voice and signaling back to the SAE/HSPA network, thus eliminating the need for 2G/ The 3G network is upgraded. Example eight

In the sixth embodiment, HSPA uses SAE as the core network, and in this embodiment, HSPA uses SGSN and Serving/PDN.

The SAE Gateway core network either uses the SGSN and GGSN core networks.

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

When the UE attaches to the SAE/HSPA network, the UE reports the SRV and NW_Init capabilities to the core network. When the UE initiates an MS voice session in the SAE/HSPA network and triggers establishment of a dedicated bearer, the core network determines that the voice session is an SRV session according to the SRV capability of the UE and the corresponding RAT type. And sending a message to notify Evolved HSPA Access, the Evolved HSPA Access may send a corresponding measurement control message to the UE, the UE performs corresponding measurement and sends a measurement report to the Evolved HSPA Access; configured on the Evolved HSPA Access 2G/3G neighbor cell PS/CS capability information and VoIP capability message. The Evolved HSPA Access makes the following judgments based on the measurement report and the target network supporting VoIP voice service capabilities:

If the 2G/3G network can carry the VoIP voice service, the bearer of the B1S voice data and the IMS signaling is transferred to the 2G/3G PS domain;

If the 2G/3G network cannot carry the VoIP voice service, the B1S signaling bearer is transferred to the 2G/3G PS domain, and the top S voice data bearer is transferred to the 2G/3G CS domain;

If the 2G/3G network does not support the PS, the top S voice data bearer is transferred to the 2G/3G CS domain.

When the UE is switched from the SAE/HSPA network to the 2G/3G network, according to the measurement report and whether the 2G/3G network can carry the VoIP voice service, the determined 2G/3G PS domain cannot carry the voice data service. The ijeNodeB notifies the core network: The B1S signaling bearer is transferred to the 2G/3G PS domain, and the B1S voice bearer is transferred to the 2G/3G CS domain.

After receiving the notification, the core network simulates a DTM handover process, and sends a corresponding handover request to the 2G/3G PS domain and the CS domain respectively, and switches the B1S voice data to the 2G/3G CS domain, and the The B1S signaling bearer is switched to the 2G/3G PS domain.

After the handover is completed, the SGSN is treated as an MSC-S/MGW, and the organization establishes a link between the SGSN and the MSC-S/MGW. The peer UE and the top S network are transparent to the entire handover process. That is, from the perspective of the peer UE, the IP address and port of the top S user plane and the signaling control plane do not change, and the PCC architecture can be used to process the subsequent handover. Signaling.

When switching from the 2G/3G network back to the SAE/HSPA network, the switch from the 2G/3G PS domain to the SAE/HSPA network is used to trigger subsequent handover from the 2G/3G CS domain back to the SAE/HSPA network. The BSC/RNC sends a PS handover request message to the SGSN, where the request message includes a context of a primary PDP (Packet Data Protocol) carrying the MS signaling and a context of a secondary PDP carrying the voice, and the SGSN sends a corresponding handover request message. Request a switch to Evolved HSPA Access, and Evolved HSPA Access establishes the corresponding radio resource.

As shown in the technical solution provided by the embodiment, when a handover between the SAE/HSPA network and the 2G/3G network is required, the technical solution of implementing the SRV at the bearer level may be adopted, that is, the bearer of the B1S signaling is switched to the target. The packet domain of the network, and the IMS voice bearer is switched to the circuit domain of the target network, and the PCC architecture is used to process the subsequent signaling from the SAE/HSPA network to the 2G/3G CS domain, so that the entire process of SRV handover to the B1S network Keeping transparent, which simplifies the switching process. On the basis of the upgrade and modification of the top S network, the continuity of the user's top S network voice service and the normal use of other services of the B1S network are guaranteed. Meanwhile, when the subsequent needs are from 2G When the /3G network is switched to the SAE/HSPA network, the switch from the 2G/3G PS domain to the SAE/HSPA network can be used to trigger the subsequent handover from the 2G/3G CS domain to the SAE/HSPA network, thereby eliminating the need for the 2G/3G network. upgrade.

Example nine

Different from the second embodiment, in the embodiment, the nis voice bearer is transferred to the switch by PS to cs to

In the 2G/3G CS domain, a new network element SRV MGW (Single Radio VCC MGW, voice continuity media gateway between single receiver top S and CS) is added to handle the top S voice bearer, ie Serving/PDN SAE. The Gateway transfers the BIS voice data to the SRV MGW, and the SRV MGW is responsible for converting the voice codec of the BIS voice data, and associating the PS bearer of the SAE/LTE with the CS bearer. The interface between the SRV MGW and the MME is the Mc interface and the S1-MME, and the interface between the SRV MGW and the Serving SAE Gateway is the S1-U interface.

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

The eNodeB may need to send a corresponding measurement control message to the UE. The measurement control message may include: supporting a PS/CS 2G/3G neighbor cell list, supporting only a 2G/3G PS neighbor cell list, and supporting only a 2G/3G CS neighbor cell list;

The UE performs measurements and sends a measurement report to the eNodeB. At this time, the top S signaling and the VoIP voice service are both carried in the SAE/LTE PS domain.

The eNodeB can make the following judgments based on the measurement report and the VoIP voice service capability of the target network: If the 2G/3G network can carry the VoIP voice service, transfer the bearer of the B1S voice data and the IMS signaling to the 2G/3G PS domain;

The technical solution provided by this embodiment can be used to implement the SRV technical solution at the bearer level when the switch between the network that establishes the IP access network and the 2G/3G network needs to be switched, that is, the pre-configuration by the eNodeB. The NIS signaling bearer is directly switched to the target network PS domain, and the nis voice bearer is switched to the target network cs domain, and the PCC architecture can be used to process the subsequent signaling after the handover, so that the entire process of the SRV handover is maintained for the nis network. Transparent, which simplifies the switching process. On the basis of the upgrade and modification of the top S network, the continuity of the user's top S network voice data and the normal use of other services of the B1S network are guaranteed. Meanwhile, when the subsequent needs are from 2G/ 3G network switches to

For SAE/LTE networks, the switch from 2G/3G to SAE/LTE PS can be used to trigger the switching of the entire top S voice and signaling back.

The SAE/LTE network process eliminates the need to upgrade 2G/3G networks.

As shown in FIG. 12, the flow of the IMS voice service from the SAE/LTE network to the 2G/3G network is shown in this embodiment. In step 12-11, the MME notifies the SRV MGW to prepare the corresponding CS resource, and establishes an inter-office bearer.

In steps 12-13, the MME notifies the Serving/PDN SAE Gateway to transfer the top S voice data to the SRV MGW.

The SRV MGW is responsible for processing the top S voice bearer, and associates the PS bearer of the SAE/LTE with the CS bearer, and the SRV MGW is responsible for the conversion of the voice codec of the top S voice data.

The other subsequent steps are the same as in Example 2.

In the PS domain, the nis voice data bearer is switched to the target network cs domain, or both the nis signaling bearer and the nis voice data bearer are switched to the target network PS domain, or only the nis voice data bearer is switched to the target network cs domain, The nis signaling data is transferred to the RUA, and the corresponding top S voice service PS domain bearer and the CS domain bearer are associated through the core network, and the subsequent PCC architecture can be used to process the follow-up letter from the SAE/LTE network to the 2G/3G network. Therefore, the entire process of SRV handover is transparent to the nis network, thereby simplifying the handover process, and ensuring the continuity of the user's top s network voice service and other services of the top s network without upgrading and modifying the nis network. Normal use; At the same time, when switching from the 2G/3G network back to the SAE/LTE network, the PS switch from the 2G/3G network to the SAE/LTE network can be used to trigger the entire top S voice and signaling switch back to SAE/ LTE network process, thus eliminating the need Upgrade the 2G/3G network.

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. In this embodiment, the SAE/HSPA network preferentially uses the B1S signaling bearer and the B1S voice. The bearer is transferred to the 2G/3G PS domain, and according to the feedback of the 2G/3G network, it is judged whether the 2G/3G network can support the VoIP voice service. If the feedback result is that the 2G/3G network cannot carry the VoIP voice service, the top S is The signaling bearer is transferred to the 2G/3G PS domain, and the top S voice data bearer is transferred to the 2G/3G CS domain.

When the UE attaches or bears the SAE/HSPA network, the UE reports the SRV and the _Init capability. When the UE initiates a top S session in the SAE/HSPA network and triggers the establishment of the dedicated bearer, the core network determines that the session is an SRV session according to the SRV capability of the UE.

The SAE/HSPA network preferentially transfers both the top S signaling bearer and the top S voice bearer to the 2G/3G PS domain, that is, the eNodeB initiates a handover from SAE/HSPA to 2G/3G PS, and the IMS signaling bearer The top S voice bearers are all transferred to the 2G/3G PS domain. At this time, the top S signaling bearer and the VoIP voice bearer are both in the SAE/HSPA PS domain.

If the 2G/3G network cannot carry VoIP voice services and feed back to the SAE/HSPA network. The Evolved HSPA

Access initiates an analog DTM handover, and transfers the top S signaling bearer to the 2G/3G PS domain through PS handover, and transfers the top S voice bearer to the 2G/3G CS domain through PS to CS handover. The eNodeB may need to send a corresponding measurement control message to the UE. The measurement control message includes: a list of neighboring cells supporting PS/CS at the same time, and the UE performs corresponding measurement and sends a measurement report to the wireless side.

The Evolved HSPA Access instructs the EPC to initiate a DTM Handover procedure, switching the top S signaling bearer to a 2G/3G PS domain, switching the IMS voice data bearer to a 2G/3G CS domain, and, related dedicated bearer Context information is kept in the core network;

After the B1S voice data bearer is switched to the 2G/3G CS domain, the PCC architecture is used to process the subsequent signaling after the handover.

When it is necessary to switch back to the SAE/HSPA network from the 2G/3G network, the PS switch from 2G/3G to SAE/HSPA can be used to trigger subsequent switching from the MS service to the SAE/HSPA from the 2G/3G network.

As shown in the technical solution provided by the embodiment, when a handover between the SAE/HSPA network and the 2G/3G network is required, the technical solution of implementing the SRV at the bearer level may be adopted, that is, the bearer of the B1S signaling is switched to the target. The packet domain of the network, and the IMS voice bearer is switched to the circuit domain of the target network, and the PCC architecture is used to process the The SAE/HSPA network switches to the subsequent signaling of the 2G/3G CS domain, so that the entire process of SRV handover is transparent to the BIS network, which simplifies the handover process and ensures users without upgrading and modifying the top S network. The continuity of the top S network voice service and the normal use of other services of the B1S network; meanwhile, when the subsequent handover from the GSM network to the SAE/HSPA network is required, the PS switch from the 2G/3G to the SAE/HSPA network can be used to trigger the entire The top S voice and signaling are switched back to the SAE/LTE network process, so that there is no need to upgrade the 2G/3G network.

Embodiment 11

In the embodiment, when the B1S voice bearer is transferred to the 2G/3G CS domain by the PS to CS handover, a new network element SRV MGW is added to process the top S voice bearer, that is, the Serving/PDN SAE Gateway will be the top S. The voice data is transferred to the SRV MGW, and the SRV MGW is responsible for converting the voice codec of the B1S voice data, and associating the PS bearer of the SAE/LTE with the CS bearer. Transfer IMS signaling to the RUA.

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

The UE performs measurements and sends a measurement report to the eNodeB. At this time, the top S signaling and the VoIP voice service are carried in

SAE/LTE PS domain.

As shown in FIG. 13 and FIG. 14 , a flow chart of switching an IMS voice service from an SAE/LTE network to a 2G/3G network according to an embodiment of the present invention is as follows: When the UE switches from the SAE/LTE network to the 2G/3G network, the eNodeB can determine that the target 2G/3G PS domain cannot support the packet domain service according to the measurement report and whether the 2G/3G network has the capability of carrying the VoIP voice service. The core network is notified: The signaling bearer of the nis session is transferred to the RUA, and the nis voice bearer is transferred to the target network CS domain by the handover of ps to cs.

After receiving the handover notification, the core network sends a corresponding handover request to the cs domain, and switches the nis voice data to

The 2G/3G CS domain transfers the signaling bearer of the IMS session to the RUA.

After the handover is completed, the signaling data of the top S session is transferred to the RUA, and the RUA proxy functions of the UE in the top S domain to keep the UE in the top S network registration and session state; Serving/PDN SAE Gateway will top S The voice data is forwarded to the SRV MGW, and the top S signaling data is forwarded to the RAU. The SRV MGW organization establishes a link between the SRV MGW and the MSC-S/MGW. From the perspective of the peer UE, the IP address and port of the top S user plane and the signaling control plane have not changed.

In the PS domain, the nis voice data bearer is switched to the target network cs domain, or both the nis signaling bearer and the nis voice data bearer are switched to the target network PS domain, or only the nis voice data bearer is switched to the target network cs domain, The nis signaling data is transferred to the RUA, and the corresponding top S voice service PS domain bearer and the CS domain bearer are associated through the core network, and the subsequent PCC architecture can be used to process the follow-up letter from the SAE/LTE network to the 2G/3G network. Therefore, the entire process of SRV handover is transparent to the nis network, thereby simplifying the handover process, and ensuring the continuity of the user's top S network voice service and other services of the top S network without upgrading and modifying the nis network. Normal use.

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

The determining module 1 is configured to determine whether the session needs to be switched. Specifically, the determining may be performed according to the measurement report sent by the received terminal.

The processing module 1 is configured to transfer the signaling bearer of the session to the target network PS domain when the session needs to be switched from the source network to the target network; and transfer the voice data bearer of the session to the target network CS domain. Specifically, the PS domain to PS domain handover may be used to transfer the signaling bearer of the session to the target network PS domain. Specifically, the PS domain to CS domain handover may be used to transfer the voice data bearer of the session to the CS domain of the target network; or, in the process of transferring the signaling bearer of the session to the target network PS domain, the source network Assigning a routing number; establishing a CS domain bearer to the target network according to the routing number; and associating the PS domain bearer with the CS domain bearer according to the routing number.

The processing module 1 in the embodiment of the present invention may further switch the signaling bearer of the session from the target network to the source network by using PS domain to PS domain handover; establish a voice data bearer of the session in the source network; or In from In the case that the target network is switched back to the source network, the voice data bearer and the signaling bearer of the session are switched back to the source network by using PS domain to PS domain handover.

In the case that the judgment needs to be made according to the measurement report, the base station may further include:

The receiving module 1 is configured to receive a measurement report sent by the terminal. In this way, the determining module 1 is configured to determine, according to the measurement report received by the receiving module, whether the session needs to be switched.

In the embodiment of the present invention, when the network is attached or the bearer is established, the terminal may report the capability of maintaining the continuity of the voice, or pre-statically configuring the terminal to maintain the continuity of the voice in the network; The ability to maintain voice continuity, the network side determines that the session initiated by the terminal is a session that needs to maintain the continuity of the voice.

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

The processing module 2 is configured to: when the session needs to be switched from the source network to the target network, to switch the session from the source network to the target network, where the method includes: when the determining module 2 determines that the session needs to be switched from the source network to the target network, And transferring the voice data bearer of the session to a PS domain of the target network or a CS domain of the target network, and transferring the signaling bearer of the session to a PS domain or a remote user agent of the target network.

The receiving module 2 is configured to receive a measurement report sent by the terminal. In this way, the determining module 2 is configured to determine, according to the measurement report received by the receiving module 2, whether the session needs to be switched.

In the foregoing apparatus, the determining module 3 is further 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 services,

The processing module 2 transfers the signaling bearer of the session and the voice data bearer of the session to the target network PS domain; if it is determined that the target network cannot carry the VoIP voice service,

Processing module 2, transferring the voice data bearer of the session to the target network CS domain;

If it is determined that the target network cannot carry the VoIP voice service and does not support the PS domain,

The processing module 2 transfers the voice data bearer of the session to the target network CS domain, and transfers the signaling bearer of the session to the remote user agent.

The processing module 2 in the embodiment of the present invention may also be processed according to the configuration in the network side, for example: may be configured on the network side: transfer the signaling bearer of the session to the target network PS domain, and the session Transmitting the voice data bearer to the target network CS domain; or transferring the signaling bearer of the session and the voice data bearer of the session to the target network PS domain; or transferring the voice data bearer of the session to the The target network CS domain, Transfer the signaling bearer of the session to a remote user agent.

The session in the embodiment of the present invention may be a nis session, such that the processing module 2 may transfer the signaling data of the nis session to a remote user agent; and transfer the voice data bearer of the nis session to the target network cs area.

It can be seen from the apparatus provided in this embodiment that when switching between the source network and the target network is required, the wireless side makes session signaling and session voice data according to the measurement report of the UE and the capability of the VoIP voice service of the target network. The switching mode ensures that the entire switching process is transparent to the network on the basis of ensuring the continuity of the voice service of the user, thereby eliminating the need to upgrade the network.

The above is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think of changes or within the technical scope disclosed by the present invention. Alternatives are intended to be covered by the scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

Claim

A method for implementing voice continuity of a session, comprising:

The method for implementing the voice continuity of a session according to claim 1, wherein the method for transferring the signaling bearer of the session to the PS domain of the target network is:

The signaling bearer of the session is transferred to the target network PS domain using a PS domain to PS domain handover.

The method for implementing the voice continuity of a session according to claim 1, wherein the method for transferring the voice data bearer of the session to the CS domain of the target network comprises:

Transferring the voice data bearer of the session to the CS domain of the target network using a PS domain to CS domain 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 a CS domain bearer to the target network according to the routing number; and the PS according to the routing number The domain bearer is associated with the CS domain bearer.

The method for implementing voice continuity of a session according to claim 1, wherein the method further comprises:

And switching the signaling bearer of the session from the target network to the source network by using a PS domain to the PS domain handover; establishing a voice data bearer of the session in the source network; or

In the case of switching from the target network back to the source network, the PS domain to PS domain handover is used to switch the voice data bearer and signaling bearer of the session back to the source network.

The method for implementing voice continuity of a session according to any one of claims 1 to 4, wherein before the session is switched from the source network to the target network, the method further includes:

The network side receives the measurement report sent by the terminal, and determines, according to the measurement report, that the session needs to be switched from the source network to the target network.

The method for implementing the voice continuity of a session according to any one of claims 1 to 4, wherein the determining that the session is a session that needs to maintain voice continuity comprises:

When the network is attached or the bearer is established, the terminal reports the ability to maintain voice continuity, or pre-statically configures the terminal to maintain voice continuity in the network;

The network side determines that the session initiated by the terminal is required according to the capability of the terminal to maintain voice continuity. A session that maintains the continuity of speech.

7. A method for implementing voice continuity of a session, comprising:

The session is a session that needs to maintain voice continuity, when the session is switched from the source network to the target network: transferring the voice data bearer of the session to the PS domain of the target network or the CS domain of the target network Transmitting the signaling bearer of the session to the PS domain of the target network or a remote user agent.

The method for implementing voice continuity of a session according to claim 7, wherein before the session is switched from the source network to the target network, the method further includes:

The method for implementing the voice continuity of the session according to claim 7 or 8, wherein the method for transferring the voice data bearer and the signaling bearer comprises:

And transmitting, in the case that the target network supports the VoIP voice service, the signaling bearer of the session and the voice data bearer of the session to the target network PS domain;

If the target network does not support the VoIP voice service, the signaling bearer of the session is transferred to the target network PS domain, and the voice data bearer of the session is transferred to the target network CS domain;

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

The method for implementing voice continuity of a session according to claim 7 or 8, wherein before the session is switched from the source network to the target network, the method further includes:

Configure on the network side:

Transferring the signaling bearer of the session to the target network PS domain, and transferring the voice data bearer of the session to the target network CS domain; or

Transmitting the signaling bearer of the session and the voice data bearer of the session to the target network PS domain; or transferring the voice data bearer of the session to the target network CS domain, and signaling the session Transfer to a remote user agent.

The method for implementing voice continuity of a session according to claim 7 or 8, wherein the session is an Internet S-substance top S session, and the method for transferring voice data bearer and signaling bearer is specific Includes:

Transferring signaling data of the nis session to a remote user agent;

Transferring the voice data bearer of the nis session to the target network cs domain.

The method for implementing voice continuity of a session according to claim 11, wherein the method for transferring a signaling bearer of a nis session to a remote user agent comprises:

If the remote user agent is attached to the mobility management entity MME entity, the MME notifies the serving gateway Serving Gat eway to transfer the signaling data of the top S session to the remote user agent functional entity in the MME;

The remote user agent delegates the function of the UE in the top S domain to maintain the UE's top-S network registration and session status.

The method for implementing the voice continuity of a session according to claim 11, wherein the method for transferring the voice data bearer of the nis session to the CS domain of the target network comprises:

Transferring the voice data bearer of the nis session to the cs domain of the target network using a PS domain to cs domain switch; or

In the process of transferring the signaling bearer of the nis session to the remote user agent, the source network allocates a routing number; establishes a cs domain bearer to the target network according to the routing number; and carries the PS domain according to the routing number Associated with the cs domain bearer.

A base station, the base station comprising:

The base station according to claim 14, wherein the base station further comprises:

The receiving module 1 is configured to receive a measurement report sent by the terminal;

The determining module 1 is configured to determine, according to the measurement report received by the receiving module, whether the session needs to be switched.

16. A device for implementing voice continuity of a session, the device comprising:

The processing module 2 is configured to: when the determining module 2 determines that the session needs to be switched from the source network to the target network, transfer the voice data bearer of the session to the PS domain of the target network or the CS of the target network. The domain transfers the signaling bearer of the session to a PS domain of the target network or a remote user agent.

The device according to claim 16, wherein the device further comprises:

The receiving module 2 is configured to receive a measurement report sent by the terminal;

The determining module 2 is configured to determine, according to the measurement report received by the receiving module 2, whether the session is needed. Switch.

The device according to claim 16 or 17, wherein the device further comprises: a determining module 3, configured to determine whether the target network can carry the VoIP voice service;

The processing module 2 is configured to: when the result of the determining by the determining module 3 is that the target network can carry the VoIP voice service, transfer the signaling bearer of the session and the voice data bearer of the session to the PS domain of the target network; Or for transmitting the voice data bearer of the session to the target network CS domain when the result of the determining module 3 is that the target network cannot carry the VoIP voice service; or

When the result of the determining by the determining module 3 is that the target network cannot carry the VoIP voice service and does not support the PS domain, and is configured to transfer the voice data bearer of the session to the target network CS domain, where The signaling bearer of the session is transferred to the remote user agent.