WO2011140888A1

WO2011140888A1 - Communication system and method for enhanced single radio voice call continuity

Info

Publication number: WO2011140888A1
Application number: PCT/CN2011/073051
Authority: WO
Inventors: 陶全军; 谢振华; 游世林; 王鸿彦
Original assignee: 中兴通讯股份有限公司
Priority date: 2010-05-10
Filing date: 2011-04-20
Publication date: 2011-11-17
Also published as: CN102244910B; CN102244910A

Abstract

A communication system and method for enhanced Single Radio Voice Call Continuity (SRVCC) are provided by the present invention. The method includes the following steps: tunnel connection is established between an enhanced Mobile Switching Center (eMSC) and a Packet Data Network Gateway (P-GW) for a User Equipment (UE) in the circuit switched domain of the source network; when a session between the UE and a remote equipment is established, the eMSC establishes the session communication from the circuit switched domain to the packet switched domain for the UE and the remote equipment via the P-GW through the established tunnel connection; and in the process of voice call continuity handover from the circuit switched domain to the packet switch domain, the bearer connection between the UE and the P-GW in the target network is established; the P-GW connects the bearer connection between the UE and the P-GW with the remote equipment, and provides the session communication between the UE and the remote equipment. The present invention can efficiently reduce the problem that the interruption duration is too long in voice call continuity handover in the art, and improve the user experience greatly.

Description

Communication system and method for enhancing continuity of single access voice service

Technical field

The present invention relates to the field of mobile communication technologies, and in particular, to a communication system and method for enhancing continuity of a single access voice service.

Background technique

In order to maintain the strong competitiveness of the 3rd Generation Partnership Project (3GPP) in the field of mobile communications, 3GPP is currently working on the Packet Switched Core (PS). Core) and the evolution of the Universal Mobile Telecommunication System Radio Access Network (UTRAN), the purpose of which is to enable the evolved PS Core (EPC) to provide higher transmission rates and shorter transmissions. Delay, and support E-UTRAN (Evolved UTRAN, Evolved UTRAN), GERAN (GSM EDGE radio access network, GSM EDGE radio access network, where GSM is the abbreviation of Global System for Mobile communications, namely Global System for Mobile Communications, EDGE It is the abbreviation of Enhanced Data Rate for GSM Evolution, namely, enhanced data rate GSM evolution technology), UTRAN, WLAN (Wireless Local Area Network) and other non-3GPP access networks. This evolved mobile communication system is called an evolved packet domain system (Evolved Packet System, abbreviated as EPS).

The EPS system architecture is shown in Figure 1, including:

E-UTRAN 11 for implementing all wireless functions related to the evolved network;

Mobility Management Entity (ΜΜΕ) 12 is responsible for control plane mobility management, including user context and mobility state management, assigning user temporary identity, etc.

The Serving Gateway (S-GW) 13 is a user plane entity responsible for user plane data routing processing;

Packet Data Network Gateway (PDN GW or P-GW) 14. Responsible for the gateway function of the UE to access the PDN (Packet Data Network). P-GW14 and S-GW13 may be combined in one physical entity;

SGSN (Serving GPRS Supporting Node) 15 is a service GPRS support node;

A Policy and Charging Rule Function (PCRF) 16 is used for policy control decisions and flow charging control functions;

The Home Subscriber Server (HSS) 17 is used to store user subscription information.

Figure 2 shows the system architecture of the existing Single Radio Voice Call Continuity (SRVCC) system. UTRAN/GERAN21 is mainly used for 3G/2G Circuit Switch (CS) domain network access; Source Mobile Switch Center (Source MSC) 22 is mainly used for users in the source circuit switching network user plane. And the signaling exchange function; the Enhanced Mobile Switch Center (eMSC) 23 is configured to help the Single Radio UE complete the voice continuity between the CS domain and the Packet Switch (PS), and the network element can The source MSC is deployed as the same network element.

IP Multimedia Core Network Subsystem (IMS) is an IP-based network architecture proposed by the 3rd Generation Partnership Project (3GPP) to build an open and flexible service. The environment, supporting multimedia applications, can provide users with rich multimedia services.

In the IMS service system, the control layer and the service layer are separated. The control layer does not provide specific services, and only provides the necessary triggering, routing, and accounting functions to the service layer.

The service triggering and control function in the control layer is completed by the Call Session Control Function (CSCF). The call session control functions are divided into: proxy call session control function (Proxy-CSCF, referred to as P-CSCF), query call session control function (Interrogating-CSCF, referred to as I-CSCF) and service call session control function (Serving-CSCF, referred to as S-CSCF) Three types, of which the primary responsibility is S-CSCF, and the I-CSCF is optional.

The service layer is composed of a series of application servers (ASs), which can provide specific service services. The AS can be an independent entity or exist in the S-CSCF.

2 181102450 The key technologies of the single access voice service continuity are mainly the signaling and user interaction processing between the CS and the PS network. To simplify the description, the related network elements in the IMS network are collectively referred to herein as the IMS network element 24.

Figure 3 shows the existing single-access voice service continuity switching from the circuit switched domain to the packet switched domain.

(CS to PS) Flowchart, describing that the SR UE initially establishes a session with the remote device on the circuit domain network, signaling and traffic anchored in the IP Multimedia Subsystem (IMS). If a network handover occurs, the SR UE will subsequently have a single access voice service continuity process, and the SR UE accesses from the LTE network, and the media connection with the remote device needs to be re-established to maintain the continuous session process. The process includes the following steps. Steps:

Step 301: The GERAN/UTRAN network determines to initiate handover to the E-UTRAN according to the radio measurement report reported by the SR UE.

Step 302: The GERAN/UTRAN sends a handover request message (HO Required) to the source MSC, where the message carries a target cell identifier that points to the target E-UTRAN network.

Step 303: The Source MSC sends a Prepare HO Request to the eMSC according to the target cell identifier in the message, and notifies the target network to perform handover.

Step 304: The eMSC determines that the SR UE does not have network resources in the target E-UTRAN network, and determines whether the target E-UTRAN network has network resources that can be provided to the user UE, and the eMSC can query the target network MME or query inside the device.

Step 305: The eMSC returns a handover preparation response message to the Source MSC (Prepare HO

The message carries a Networl Access Indicator (NAI), and the network access indication is used to notify the SR UE to access the newly created network resource on the E-UTRAN network to complete the handover;

Step 306: The Source MSC returns a handover response message (HO Response) to the source GERAN/UTRAN network, where the message carries a network access indication.

Step 307: The source GERAN/UTRAN sends a handover command (HO Command) to notify the SR UE to perform handover. The message carries a network access indication, indicating that the UE accesses the E-UTRAN network, and newly establishes a network resource to complete the handover; Step 308: The SR UE receives the handover command, switches to the E-UTRAN network according to the network access indication NAI, and initiates a standard tracking area update (TAU); because the SR UE switches from the GERAN/UTRAN network to the E - UTRAN network, at this time, the user plane connection between the SR UE and the GERAN/UTRAN is broken, and the service bearer in the E-UTRAN network has not been established yet, and the SR UR and the remote device are temporarily unable to communicate, so the single access voice service is The continuity will be interrupted, causing a temporary voice interruption in the voice communication between the user equipment UE and the remote device.

Step 309: The SR UE establishes a required bearer in the E-UTRAN network, and the establishment process is a standard PS bearer establishment process, which is not described in detail herein;

Step 310: After the bearer is established, the SR UE registers with the IMS network of the user's home location. Step 311: The registration is successful, and the SR UE sends a session invitation message (INVITE) to the home IMS network, and the message is statically configured in the UE. Session Transfer Indication (STI), indicating that the IMS network element is used for service continuity (Service Continuity, SO. The IMS network element connects the remote IP device by updating the process of the remote device. The source MSC is updated to be directly connected to the SR UE, and may pass some EPS network elements and other network devices in the middle. This step is a standard business continuity SC process, which is not described in detail herein; Step 312: The process of the remote device is successfully updated. Afterwards, the IMS network element returns a success message (200 OK) to the SR UE.

After receiving the 200 Ok message, the SR UE resumes voice communication with the remote device, and completes the SR UE to switch voice continuity between the CS domain and the PS domain.

It can be seen from the foregoing process shown in FIG. 3 that in the existing method for implementing single-access voice service continuity, in steps 310-312, an update operation needs to be performed on the remote device, and the IP multimedia subsystem IMS signaling delay is delayed. Longer, this will cause the call interruption time to be too large, and even affect the normal communication of the user, resulting in a decline in user experience. Summary of the invention

The technical problem to be solved by the present invention is to provide a communication system and method for enhancing the continuity of a single access voice service, which is used to overcome the handover delay of the existing single access voice service continuity technology. The problem is that the continuity of the single-access voice service is too long due to the remote device update.

In order to solve the above problems, the present invention proposes a method for enhancing the continuity of a single access voice service, including:

Establishing a tunnel connection between the enhanced mobile switching center eMSC and the packet switching network gateway P-GW for the user equipment UE in the circuit switching domain of the source network. When the session between the UE and the remote device is established, the eMSC is established. The tunnel connection passes through the P-GW to establish session communication between the circuit switched domain and the packet switched domain for the UE and the remote device;

And establishing a bearer connection between the UE and the packet switched network gateway P-GW in the target network, in the process of the voice service continuity switching of the circuit switched domain to the packet switched domain; the P-GW, the UE and the The bearer connection between the P-GWs is connected with the remote device, and provides session communication between the UE and the remote device.

Preferably, establishing a tunnel connection between the eMSC and the P-GW for the UE in the circuit switched domain of the source network includes:

Establishing, by the eMSC, a tunnel connection between the eMSC and the P-GW when the UE attaches to the source network, or when receiving a location update request or a call setup request in the source network;

The eMSC is configured to establish a tunnel connection between the eMSC and the P-GW when the UE is attached to the source network, or when a location update request or a call setup request is received in the source network, including:

The eMSC acquires user subscription data and packet data network context information from a home network server HSS to which the user belongs, and the eMSC selects a target packet data network gateway P-GW according to the packet data network context information, and establishes the eMSC and the A tunnel connection between the target packet data network gateway P-GW, the packet data network context information including an identifier and/or an address of the target packet data network gateway P-GW.

Preferably, the packet data network context information further includes: an access point name APN and an APN indication; the APN indication is used to indicate whether the MSC is allowed to select a P-GW for the APN, or is used to indicate the APN Whether the P-GW has been allocated in the home network. Preferably,

Returning to the single access voice service continuity service rSRVCC, if the contract is signed, the eMSC registers with the IP multimedia subsystem IMS network instead of the UE. Returning to the single access voice service continuity service rSRVCC, if the contract is signed, the eMSC establishes a tunnel connection between the eMSC and the target packet data network gateway P-GW, and if not signed, the tunnel connection is not established.

Preferably, the establishing the tunnel connection between the eMSC and the P-GW further includes: the eMSC allocates a local tunnel IP resource, and sends a tunnel establishment request message to the P-GW, the tunnel establishment request The message carries the user identifier, the access point name APN, the eMSC side IP address information, and the selected target P-GW address information;

Receiving, by the P-GW, the tunnel establishment request message, determining an IP address allocated to the UE, allocating a tunnel resource, and returning a tunnel establishment request response message to the eMSC, where the tunnel establishment request response message is carried in the Determining the IP address and tunnel address information allocated by the UE to complete tunnel establishment;

The eMSC binds the IP address of the UE to the tunnel connection.

Preferably, if the tunnel connection uses a general packet radio service GPRS tunneling protocol (GTP tunnel mode), the eMSC allocates a local tunnel IP resource, and sends a tunnel establishment request message to the P-GW, the tunnel establishment request The message carrying the user identifier, the access point name APN, the eMSC side IP address information, and the selected target P-GW address information includes:

The eMSC allocates an IP address and a port number of the default bearer and the dedicated bearer, and the eMSC sends a tunnel establishment request message to the P-GW, where the tunnel establishment request message carries the user identifier, the APN, and the eMSC The IP and port number of the default bearer and dedicated bearer on the side and the selected target P-GW address information.

Preferably, the P-GW receives the tunnel establishment request message, and determines the IP address allocated to the user equipment UE by: determining whether the tunnel establishment request message carries the IP address of the UE, if not, the The P-GW assigns an IP address to the UE, and if so, uses the IP address in the message. Preferably, when the session between the UE and the remote device is established, the eMSC receives the session establishment request initiated by the UE; the eMSC passes through the established tunnel connection through the P-GW. The establishing session communication between the UE and the remote device includes:

The eMSC allocates a media side media resource of the user, and sends a session invitation message to the remote device, where the session invitation message carries the media IP address and port number of the UE;

When the eMSC receives the session completion message returned by the remote device, the media IP address and port number of the remote device carried in the session completion message, the eMSC sends a call setup response message to the UE, and connects to the The wireless side media resource is connected to the tunnel; and

The P-GW associates with the tunnel connection by using an IP address assigned by the P-GW to the UE; the UE is established by the eMSC, the tunnel connection, the P-GW, and the remote device. Session communication from the circuit switched domain to the packet switched domain.

Preferably, when the session between the UE and the remote device is established, the eMSC receives a session invitation message initiated by the remote device, and the eMSC passes the P-GW through the established tunnel connection. Establishing session communication for the UE and the remote device includes:

Receiving, by the eMSC, a session invitation message initiated by the remote device, where the session invitation message carries a media IP address and a port number of the remote device, where the eMSC sends a message to the UE that is called by the remote device. a call setup request message, and allocating a radio side media resource of the called UE; the eMSC receiving the call response message of the called UE, and sending a session invitation complete message to the remote device, in the session invitation completion message Carrying the media IP address and the port number of the called UE, the eMSC sending a call setup response message to the UE, and connecting the radio side media resource to the tunnel connection; the P-GW passing the P-GW The IP address assigned to the UE is associated with the tunnel connection; the UE establishes a session of the circuit switched domain to the packet switched domain through the MSC, the tunnel connection, and the P-GW and the remote device communication.

Preferably, the eMSC establishes a session communication between the UE and the remote device, the method further includes: the eMSC negotiating the media information with the remote device, and notifying the local UE of the media information, where the media information includes Codec information and voice media source and destination IP addresses and ports. Preferably, the voice service continuity switching from the circuit switched domain to the packet switched domain is The UE is handed over from the source network to the target network, and the UE initiates handover from the source network to the target network according to the radio quality change.

The initiating handover from the source network to the target network according to the radio quality change includes: the UE sending an attach or tracking area update request message to the mobility management entity MME of the target network, where the attach or tracking area update request message is Carrying a handover indication; and the MME interacts with the P-GW according to the user subscription data acquired from the home network server HSS to which the user belongs, and establishes a bearer connection between the UE and the P-GW in the target network. And the P-GW switches the session from the tunnel connection to the bearer connection between the UE and the P-GW.

Preferably, in the process of switching the voice service continuity of the circuit switched domain to the packet switched domain, the UE switches from the source network to the target network, and the source network initiates the slave source according to the radio quality change of the user equipment UE. The network switches to the target network;

Switching from the source network to the target network by the source network according to the radio quality change of the user equipment UE includes:

The source network sends a handover request to the mobility management entity MME of the target network; and the MME interacts with the P-GW according to the user subscription data acquired from the home network server HSS to which the user belongs, and establishes a target network. a bearer connection between the UE and the P-GW, the P-GW switching a session from the tunnel connection to the bearer connection between the UE and a P-GW.

Preferably, the user subscription data includes the P-GW address, the APN, and the APN indication information. The bearer connection between the UE and the P-GW in the target network includes:

The MME sends a create bearer request message to the P-GW via the serving gateway S-GW, where the create bearer request message carries a handover indication, a user identifier, the APN, and the P-GW address;

The P-GW receives the create bearer request message, associates the tunnel connection according to the handover indication and the user identifier, and allocates an IP bearer resource of the target network; The P-GW returns a create bearer response message to the MME, and creates a bearer response message carrying the bearer resource IP address and port information allocated by the P-GW;

The MME notifies the target network to establish a bearer connection between the UE and the P-GW.

Preferably, after the bearer connection between the UE and the P-GW is established, the method further includes: receiving, by the P-GW, an update bearer request sent by the MME, according to the user identifier and the handover Instructing to associate the tunnel connection, the P-GW connecting the remote device and the established bearer connection between the UE and the P-GW.

Preferably, the method further includes: before the UE switches from the source network to the target network, the P-GW updates the current P-GW address to the HSS to which the user belongs.

Preferably, the eMSC is a separately deployed eMSC or a mobile switching center MSC deployed with the source mobile switching center.

Preferably, the source network is a global mobile communication system enhanced data rate evolved radio access network GERAN or a global mobile communication system radio access network UTRAN network; the target network is an evolved global mobile communication system radio access network E - UTRAN network.

The present invention also provides a communication system for enhancing the continuity of a single access voice service, comprising: a global mobile communication system enhanced data rate evolved radio access network GERAN as a source network or a global mobile communication system radio access network UTRAN network As an evolved global mobile communication system radio access network E-UTRAN network of the target network, the system further includes an enhanced mobile switching center eMSC, a packet switched network gateway P-GW, a home network server HSS of the user home network, and mobility management An entity MME, where the eMSC and the P-GW are connected with an S2a interface;

The eMSC is configured to establish a tunnel connection between the eMSC and the P-GW for the user equipment UE in a circuit switched domain of the source network, and the session is established when the session between the UE and the remote device is established. The tunnel connection through the P-GW to establish a session communication between the UE and the remote device to establish a circuit switched domain to a packet switched domain;

The MME, configured to: when the UE switches from a source network to a target network, according to the Establishing a bearer connection between the UE and the P-GW in a target network;

The P-GW is configured to connect the bearer connection between the UE and itself to the remote device, and provide session communication between the UE and the remote device in a target network.

Preferably, the S2a interface between the eMSC and the P-GW supports a GPRS tunneling protocol GTP and/or a proxy mobile IP protocol PMIP.

Preferably, the eMSC is further configured to select a P-GW according to the packet data network PDN context information in the user subscription data obtained from the HSS.

Preferably, the eMSC is configured to establish a tunnel connection between the eMSC and the P-GW when receiving a user location update request message, a user attach request message, or a call setup message in the source network.

Preferably, the eMSC is further configured to: after receiving the session establishment request of the local end of the UE or the session invitation message of the remote device, send the IP address allocated by the P-GW to the UE to the remote device. address.

Preferably, the communication system further includes a source mobile switching center, and the eMSC is further configured to: after receiving the handover preparation request message sent by the source mobile switching center, forward the location to the target cell in the handover preparation request message. The handover preparation request message, so that the target cell forwards the handover preparation request message to the target MME; the MME is further configured to notify the target network to allocate resources; or directly return a response message, indicating that the UE accesses The target network implements handover by using a bearer connection between the UE and the P-GW established in the target network.

Preferably, the MME is further configured to receive the handover request message of the eMSC, create a default bearer, or initiate a single access voice service user registration to the eMSC after the UE completes the tracking area update process.

The prior art anchors the session media in the IMS system, so that the process of updating the remote device needs to be too long in the process of performing the voice service continuity switching. The communication system and method for enhancing the continuity of a single access voice service according to the present invention, before the single access voice service continuity handover, the medium is anchored to the P-GW by using a tunnel connection between the enhanced MSC and the P-GW, and the handover is performed. Only the session connection needs to be switched from the tunnel connection to the bearer connection between the UE and the P-GW, and the remote device and the P-GW The connection does not need to be changed, which can effectively reduce the problem that the interruption time of the voice service continuity switching in the prior art is too long, and greatly improve the user experience. BRIEF abstract

1 is a system architecture diagram of an evolved packet domain system EPS;

2 is a structural diagram of an existing single access voice service continuity SRVCC system;

3 is a flow chart of a conventional single-access voice service continuity switching from a CS domain to a PS domain; FIG. 4 is a schematic diagram of a system architecture for enhancing single-access voice service continuity according to the present invention; FIG. FIG. 6 is a signaling flowchart of Embodiment 1 of the present invention; FIG. 6 is a schematic flowchart of a voice media path of a single access voice service;

7 is a signaling flowchart of Embodiment 2 of the present invention;

8 is a signaling flowchart of Embodiment 3 of the present invention;

9 is a signaling flowchart of Embodiment 4 of the present invention;

10 is a flow chart of UE-initiated UE handover to E-UTRAN network signaling;

FIG. 11 is a flow chart of signaling initiated by the network side to UE to switch to the E-UTRAN network. Preferred embodiment of the invention

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail with reference to the accompanying drawings.

The core idea of the present invention is to establish MSC and P- when establishing a session in a circuit switched domain (CS) to enhance single-access voice continuity during circuit switching domain (CS) to packet switched domain (PS) handover. A tunnel connection between the GWs, using the tunnel to connect the bearer session, and when the session is handed over to the packet switched domain (PS), establishing a bearer connection between the UE and the P-GW in the packet switched domain (PS), which is to be The session is switched by the tunnel connection to the bearer connection between the UE and the P-GW, and the GW-GW connects the bearer connection between the P-GWs with the remote device to establish session communication.

In the prior art, the bearer connection is established after the handover, and the IMS system needs to update the session flow of the remote device. In the present invention, the session is connected through the tunnel connection before the handover, and the remote device is The session is anchored to the P-GW. Therefore, when switching, only the tunnel connection needs to be switched to the bearer between the P-GW and the UE, and the connection between the P-GW and the remote device does not need to be changed, thus greatly The possible switching time is shortened, which can effectively enhance the continuity of single access voice service.

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

FIG. 4 is a schematic diagram of a system architecture for enhancing the continuity of a single access voice service according to the present invention. Compared with the existing system architecture shown in FIG. 2, the S2a interface between the eMSC and the S/P-GW is added to the main interface. The function of the network element mainly involves the changes of the eMSC and the MME. among them:

(1) Evolved Mobile Switching Center The main new functions of eMSC include:

a. eMSC supports S2a interface with S/P-GW, supports GPRS tunneling protocol (GPRS)

Tunnel Protocol (GTP) or Proxy Mobile IP (PMIP); b. The eMSC can select the S/P-GW according to the context information of the user's subscription packet data network PDN; c eMSC receives the user location update/attach request message Or a call setup message to establish a tunnel connection with the S/P-GW;

d. The eMSC receives the local session establishment request or the remote session invitation message, and the eMSC returns the remote media IP address set to the IP address assigned by the P-GW to the user;

e. The eMSC receives the handover preparation request message sent by the source MSC, and can forward the message to the target MME according to the target cell in the message, and notify the target network to allocate resources; or directly return a response message, instruct the UE to access the E-UTRAN network, and create a new bearer. Used for switching.

(2) The main added function of the mobility management entity MME is: When the MME receives the CS to eMSC

The PS handover request message creates a default bearer or the MME initiates a Single Radio registration to the eMSC after the UE TAU is completed.

5 is a schematic diagram of a voice media path for enhancing the continuity of a single access voice service according to the present invention. Before the handover, the SR UE accesses the GERAN/UTRAN network, and initiates a voice service with the remote device, and the service path is anchored to the user. The IMS network, the media path before the handover is: The SR UE is connected to the MSC through the GERAN/UTRAN circuit domain network, and is anchored to the P-GW through the tunnel connection, and then connected to the remote device through the IMS network. SR UE initiates handover, SR UE switches to EUTRAN The network, the switched media path is: an SR bearer connection is established between the SR UE and the P-GW, and the P-GW is connected to the SR UE and the remote device. The path diagram is visible. Before the handover, the media is anchored to the P-GW through the tunnel connection. The handover only occurs between the tunnel connection and the switched EPS bearer connection, but the connection between the P-GW and the remote device does not occur. Variety.

6 is a first embodiment of the present invention, describing that a single access user equipment SR UE is attached to a GERAN/UTRAN network, and the MSC acquires user data from the user's HSS, and determines that the user subscribes to return single access service continuity (return Single Radio Voice Call) Continuity, rSRVCC) service, and according to the packet data network context information in the user data, select the target P-GW, establish a tunnel connection with the P-GW, and when the SR UE initiates the call, the MSC voice media connects through the tunnel and the remote device. For communication, the subsequent SR UEs cause poor quality of the source network due to mobility or other reasons. The UE or the network initiates a handover procedure to switch the voice service to the EUTRAN network. The detailed procedure of the handover is as follows:

Step 601: The SR UE initiates an access procedure in the GERAN/UTRAN network, and the MSC obtains user subscription data from the HSS, where the data may include rSRVCC subscription information and an rSRVCC PDN Context, where the packet data network context information (PDN Context) includes: P-GW identity/address or APN indication, Access Point Name (APN), where the APN indication is used to indicate whether the MSC is allowed to select a P-GW for the APN, or whether the APN has already allocated a P-GW in the home network. ;

Step 602: The MSC determines that the user is an rSRVCC user, and the MSC initiates an IMS registration process in place of the UE. The process is a 3GPP standard process, which is not described in detail herein. The MSC determines that the user is an rSRVCC user, and can perform the judgment by using the subscription data obtained according to step 601, or It can be judged according to the number segment of the user identification number;

Step 603: The SR UE initiates a call, requests to establish a session with the remote device, and sends a call setup request to the MSC.

Step 604: The MSC selects a target P-GW according to the PDN Context. If the PDN Context includes the address of the P-GW, the MSC selects the P-GW in the PDN Context. If the P-GW Context does not include the P-GW address, the MSC The APN indicates the selection, where: If the APN indicates that the MSC is allowed to select, the MSC selects one according to its static configuration or the operating strategy of the operator. a local P-GW; if it is indicated that the home network has configured the P-GW, the MSC obtains the allocated P-GW address from the user home network;

If the user subscription data does not include the PDN Context, the MSC selects a local P-GW according to its static configuration or the application operation policy.

Step 605: If the network deploys the PCRF, the MSC may need to establish a signaling control connection with the PCRF, and the step is an optional step;

Step 606: The MSC sends a tunnel establishment request message to the target S/P-GW. The tunnel establishment request message carries the rSRVCC APN, the P-GW address, the SR UE identity identifier, and some other downlink tunnel security information, if the tunnel uses GTP. In the tunnel mode, the message also needs to carry the MSC to transmit the GTP tunnel IP address and port number.

Step 607: If the network deploys the PCRF, the P-GW initiates an IP connection session establishment procedure, and the P-GW provides the PCRF with a signaling connection for identifying the session and the association 605. This step is an optional step.

Step 608: The P-GW determines whether the tunnel establishment request message carries the IP address of the UE, and if not, the P-GW allocates an IP address to the SR UE; the P-GW allocates the tunnel IP resource;

Step 609: The P-GW sends an update P-GW request message to the HSS to which the SR UE belongs, where the message carries the address information of the P-GW. If the network supports the network-initiated handover mode shown in FIG. 11, the step is not needed.

Step 610: The S/P-GW returns a tunnel establishment message to the MSC, where the message carries the IP address allocated by the P-GW for the SR UE and the IP resource of the S/P-GW side tunnel. If the GTP tunnel mode is used, the P-GW A default bearer tunnel and a dedicated voice bearer tunnel may be created, and the MSC is bound to the IP address of the SR UE and the tunnel connection;

Steps 604-610 may also be completed before step 603;

Step 611: The MSC allocates the user's wireless side media resource, and sends a session invitation message to the remote end, where the message carries the local media IP address and the port number, and the IP address is set to the IP address allocated by the P-GW to the SR UE.

Step 612 - 613: The MSC receives the remote session completion message, and the MSC sends a call setup response message to the SR UE, and connects the wireless side media resource to the tunnel connection. The MSC receives the voice of the UE The data packet is converted into an IP data packet, and the destination address is set to the remote media IP address and port carried in the session response message, and is transmitted through the tunnel to the remote device through the P-GW; the IP voice media of the remote device is firstly based on The IP address of the UE is routed to the P-GW, and the P-GW finds a tunnel connection according to the UE IP address, and sends the IP data packet to the MSC through a tunnel connection, and the MSC converts the voice data packet into a voice data packet and forwards the packet to the voice packet. The UE;

Step 614: The MSC notifies the media related information negotiated by the SR UE and the remote end, such as the codec information used. If the UE does not support the currently used codec, the MSC will renegotiate the codec with the remote end; Step 615: If the MSC The media codec negotiated with the remote end is a general codec supported by the terminal. The MSC can transmit the media related information negotiated by the MSC and the far end to the PCRF through the signaling control connection established in step 605, and the PCRF occurs in the user. At the time of handover, when the target network establishes a new bearer, it is delivered to the SR UE.

Step 616: Subsequently, the SR UE switches to the target network, and the processing flow during the handover is referred to the handover process shown in FIG. 10 or FIG. 11;

Step 617: The SR UE switches to the target network. If the IMS network is not registered, the IMS re-registration process needs to be initiated. The process is a standard process.

Steps 618-619: After the SR UE is registered, the session invitation message is sent to the IMS network, and the message carries a session transfer identifier (STI), and the media address remains unchanged, and the signaling path is switched to the target network. This step is a standard IMS standard process and will not be described in detail here.

FIG. 7 is a second embodiment of the present invention. The main difference from the first embodiment is that the eMSC newly added functions are separated from the traditional MSC, that is, the eMSC is deployed separately. When the SR UE is attached or updated, the source MSC routes the location information to the eMSC and then to the HSS. The eMSC obtains the rSRVCC subscription information signed by the SR UE, and establishes a tunnel connection with the destination P-GW. The SR UE initiates the call. At the time, the Source MSC routes the call to the eMSC, which routes the call from the tunnel connection to the remote device.

Step 701: The SR UE initiates an access procedure in the GERAN/UTRAN network, and sends an attach request message to the source MSC, where the source MSC sends a location update request message to the HSS to which the user belongs. The location update request message passes through the eMSC;

Step 702: The eMSC forwards the location update request message to the HSS.

Steps 703 - 704, the HSS returns a location update response message to the eMSC, and the eMSC receives the location update response message, and obtains the SR UE subscription rSRVCC information from the location update response message, where the information includes the rSRVCC subscription information and the rSRVCC PDN Context (packet data network context) Step 705, the eMSC returns a location update response message to the Source MSC;

Step 706: The eMSC determines that the user is an rSRVCC user, and initiates an IMS registration process instead of the UE. The process is a 3GPP standard process, which is not described in detail herein. The eMSC determines that the user is an rSRVCC user, and may perform the judgment by using the subscription data obtained according to step 704, or may be based on The number segment of the user identification number is judged;

Step 707: When the SR UE initiates a call, send a call setup request message to the Source MSC.

Step 708: The Souce MSC routes the call to the eMSC.

Step 709: The eMSC selects a target P-GW according to the PDN Context. If the PDN Context includes the address of the P-GW, the eMSC selects the P-GW in the PDN Context. If the P-GW Context does not include the P-GW address, the eMSC according to the eMSC The APN indicates the selection, wherein: if the APN indicates that the eMSC is allowed to be selected, the eMSC selects a local P-GW according to its static configuration or the application operating policy; if the home network is instructed to configure the P-GW, the eMSC belongs to the user. The network obtains the assigned P-GW address;

If the user subscription data does not include the PDN Context, the eMSC selects a local P-GW according to its static configuration or the application operation policy.

Step 710: If the network deploys the PCRF, the eMSC may need to establish a signaling control connection with the PCRF, and the step is an optional step;

Step 711: The eMSC sends a tunnel establishment request to the target S/P-GW. The tunnel establishment request message carries the rSRVCC APN, the P-GW address, the SR UE identity, and some other downlink tunnel security information, if the tunnel uses the GTP tunnel. The message, the message also needs to carry the eMSC for transmitting the GTP tunnel IP address and port number;

Step 712: If the network deploys the PCRF, the P-GW initiates an IP connection session establishment procedure, and the P-GW The signaling control connection for identifying the session and association 710 steps is provided to the PCRF, which is an optional step.

Step 713: The P-GW determines whether the tunnel establishment request message carries the IP address of the UE, and if not, the P-GW allocates an IP address to the SR UE; the P-GW allocates the tunnel IP resource;

Step 714: The P-GW sends an update P-GW request message to the HSS to which the SR UE belongs, where the message carries the address information of the P-GW. If the network supports the network-initiated handover mode shown in FIG. 11, the step is not needed.

Step 715: The S/P-GW returns a tunnel acknowledgement message to the eMSC, where the message carries the IP address allocated by the P-GW for the SR UE and the IP resource of the S/P-GW side tunnel. If the GTP tunnel mode is used, the P-GW A default bearer tunnel and a dedicated voice bearer tunnel may be created, and the eMSC is bound to the IP address of the SR UE and the tunnel connection;

Steps 709-715 can also be completed before step 707;

Step 716: The eMSC allocates the user's wireless side media resource, and sends a session invitation message to the remote end, where the message carries the local media IP address and the port number, and the IP address is set to the IP address allocated by the P-GW to the SR UE.

Step 717: The eMSC receives the remote session completion message, where the session completion message carries the IP address allocated by the P-GW to the SR UE.

Step 718: The eMSC receives the session completion message, and returns an address completion message to the source MSC. Step 719: The source MSC sends a call setup response message to the SR UE, and connects the radio side media resource to the tunnel connection.

Steps 720-721: The eMSC notifies the media information related to the far-end negotiation between the SR UE and the remote end, such as the codec information used. If the UE does not support the currently used codec, the MSC will renegotiate the codec with the remote end; The media codec negotiated by the remote end is a general codec supported by the terminal. The eMSC can transmit the media related information negotiated by the MSC and the far end to the PCRF through the signaling control connection established in step 707, and the PCRF switches in the user. When the target network establishes a new bearer, it is delivered to the SR UE;

After the session is established, the eMSC receives the voice data packet of the UE and converts it into an IP data packet, and the destination address is set to the remote media IP address and port carried in the session response message, and is connected through a tunnel. The IP voice media of the remote device is first routed to the P-GW according to the IP address of the UE, and the P-GW finds a tunnel connection according to the UE IP address, and passes the IP data packet through the tunnel. The connection is sent to the eMSC, and the eMSC is converted into a voice data packet and then forwarded to the UE;

Step 722: Subsequently, the SR UE switches to the target network, and the processing flow during the handover is referred to the handover process shown in FIG. 10 or FIG. 11;

Step 723: The SR UE switches to the target network. If the IMS network is not registered, the IMS re-registration process needs to be initiated. The process is a standard process.

Steps 724-725: After the SR UE is registered, the session invitation message is sent to the IMS network, where the message carries a Session Transfer Identification (STI), and the media address remains unchanged, and the signaling path is switched to the target network. This step is a standard IMS standard process and will not be described in detail here.

FIG. 8 is a third embodiment of the present invention. The difference from the first embodiment is that the tunnel mode in the embodiment uses the GTP tunnel mode to create a default bearer when the user attaches, and then receives a call request and then applies a dedicated 7-pass voice;

Step 801: The SR UE initiates an access procedure in the GERAN/UTRAN network, and the MSC obtains user subscription data from the HSS. The user subscription data may include rSRVCC subscription information and an rSRVCC PDN Context, where the packet data network context information PDN Context includes: P-GW identity/address or APN indication, Access Point Name (APN), where the APN indication is used to indicate whether the MSC is allowed to select a P-GW for the APN, or whether the APN has already allocated a P-GW in the home network. ;

Step 802: The MSC selects a target P-GW according to the PDN Context. If the PDN Context includes the address of the P-GW, the MSC selects the P-GW in the PDN Context. If the P-GW Context does not include the P-GW address, the MSC Selecting according to the APN indication, where: if the APN indicates that the MSC is allowed to select, the MSC selects a local P-GW according to its static configuration or the application operating policy; if the home network is instructed to configure the P-GW, the MSC sends the user to the user. The home network obtains the allocated P-GW address;

If the user subscription data does not contain the PDN Context, the MSC is configured according to its own static configuration. Or use a business operation strategy to select a local P-GW;

Step 803: The MSC simulates that the S-GW sends a default bearer request to the P-GW, where the message carries the user identifier, and the MSC is the IP address and port number assigned by the default bearer, the P-GW address, the bearer identifier, and the APN information.

Step 804: If the network deploys the dynamic PCRF, the P-GW obtains the user's policy and charging control criteria from the PCRF, and determines whether the user is allowed to establish the requested bearer.

Step 805: The P-GW allocates an IP address to the SR UE, and a user plane IP address and a port number of the default bearer.

Step 806: The P-GW returns a default bearer response message to the MSC, where the message carries the user plane IP address and port number of the default bearer.

Step 807: The MSC determines that the user is an rSRVCC user, and the MSC initiates an IMS registration process in place of the UE. The process is a 3GPP standard process, which is not described in detail herein. The MSC determines that the user is an rSRVCC user, and can perform the judgment by using the subscription data obtained in step 801, or It can be judged according to the number segment of the user identification number;

Step 808: The SR UE initiates a call request, and sends a call setup request message to the MSC. Step 809: The MSC simulates that the S-GW sends a setup dedicated bearer request message to the P-GW, where the message carries a Linked Bearer Id (LBI). QoS, and Traffic Flow Template (TFT). The LBI is mainly used to associate the default bearers established in steps 803 to 806; QoS is used to notify the P-GW of the required resource quality requirements;

Step 810: If the dynamic PCRF is deployed, the P-GW notifies the PCRF, and the PCRF determines whether the SR UE is allowed to apply for the bearer resource.

Step 811: If the establishment is allowed, the P-GW allocates the required bearer resource, and returns a special bearer request response message to the MSC, where the message carries the P-GW side bearer IP address and port number;

Step 812: The MSC allocates the user's wireless side media resource, and sends a session invitation message to the remote end, where the message carries the local media IP address and the port number, and the IP address is set to the IP address allocated by the P-GW to the SR UE.

Step 813: The MSC receives the remote session completion message, where the remote session completion message carries the IP address allocated by the P-GW to the SR UE.

Step 814: The MSC sends a call setup response message to the SR UE, and connects the wireless side media resource. Connected to the tunnel. The MSC receives the voice data packet of the UE and converts it into an IP data packet, and the destination address is set to the remote media IP address and port carried in the session response message, and is sent to the remote device through the P-GW through the tunnel connection; The IP voice media of the end device is first routed to the P-GW according to the IP address of the UE, and the P-GW finds a tunnel connection according to the UE IP address, and sends the IP data packet to the MSC through a tunnel connection, where the MSC After being converted into a voice data packet, the packet is forwarded to the UE. Step 815: The MSC notifies the SR UE of the media related information negotiated with the remote end, such as the codec information used. If the UE does not support the currently used codec, the MSC will The remote renegotiation codec is performed. Step 816: If the media codec negotiated by the MSC and the remote end is a general codec supported by the terminal, the MSC can negotiate the connection established by the step 810 to negotiate the MSC with the remote end. The media related information is transmitted to the PCRF, and is transmitted to the SR UE by the PCRF when the user establishes a new bearer when the user initiates the handover.

Step 817: Subsequently, the SR UE switches to the target network, and the processing flow during the handover is referred to the handover process shown in FIG. 10 or FIG. 11;

Step 818: The SR UE switches to the target network. If the IMS network is not registered, the IMS re-registration process needs to be initiated. The process is a standard process.

Steps 819-820: After the SR UE is registered, the session invitation message is sent to the IMS network, and the message carries the Session Transfer Indentation (STI), the media address remains unchanged, and the signaling path is switched to the target network. This step is a standard IMS standard process and will not be described in detail here.

FIG. 9 is a fourth embodiment of the present invention. The difference between this embodiment and the first embodiment is that when the SR UE receives the called party, the MSC receives the session invitation message sent by the remote end from the P-GW, and returns the session to the remote end. Completing the message, the media address in the message is filled in as the SR UE IP address allocated by the P-GW; Step 901: The SR UE initiates an access procedure on the GERAN/UTRAN network, and the MSC obtains user subscription data from the HSS, and the data may include the rSRVCC subscription. Information and rSRVCC PDN Context, the packet data network context information PDN Context includes: a target P-GW identity/address or an APN indication, an Access Point Name (APN), where the ΑΡΝ indication is used to indicate whether to allow the MSC Select P-GW for ΑΡΝ, or whether APN has already allocated P-GW in the home network; Step 902: The MSC determines that the user is an rSRVCC user, and the MSC initiates an IMS registration process in place of the UE. The process is a 3GPP standard process, which is not described in detail herein. The MSC determines that the user is an rSRVCC user, and can perform the judgment by using the subscription data obtained in step 901, or It can be judged according to the number segment of the user identification number;

Step 903: The MSC receives the remote session invitation message, where the message carries the remote user plane IP address and port number.

Step 904: The MSC selects a target P-GW according to the PDN Context. If the PDN Context includes the address of the P-GW, the MSC selects the P-GW in the PDN Context. If the P-GW Context does not include the P-GW address, the MSC according to the MSC The APN indicates the selection, wherein: if the APN indicates that the MSC is allowed to select, the MSC selects a local P-GW according to its static configuration or the application operation policy; if the home network is instructed to configure the P-GW, the MSC belongs to the user. The network obtains the assigned P-GW address;

Step 905: If the network deploys the PCRF, the MSC may need to establish a signaling control connection with the PCRF, and the step is an optional step;

Step 906: The MSC sends a tunnel establishment request to the target S/P-GW. The tunnel establishment request message carries the rSRVCC APN, the P-GW address, the SR UE identity, and some other downlink tunnel security information, if the tunnel uses the GTP tunnel. The MSC is also required to carry the GTP tunnel IP address and port number in the message.

Step 907: If the network deploys the PCRF, the P-GW initiates an IP connection session establishment procedure, and the P-GW provides the PCRF with a signaling connection for identifying the session and association 905. This step is an optional step;

Step 908: The P-GW determines whether the tunnel establishment request message carries the IP address of the UE, and if not, the P-GW allocates an IP address to the SR UE; the P-GW allocates the tunnel IP resource;

Step 909: The P-GW sends an update P-GW request message to the HSS to which the SR UE belongs, where the message carries the address information of the P-GW. If the network supports the network-initiated handover mode shown in FIG. 11, the step is not needed.

Step 910: The S/P-GW returns a tunnel acknowledgement message to the MSC, where the message carries the P-GW. The IP address assigned to the SR UE and the S/P-GW side tunnel IP resource. If the GTP tunnel mode is used, the P-GW may create a default bearer tunnel and a dedicated voice bearer tunnel. The MSC binds the IP address and tunnel of the SR UE. connection;

Step 911 - 913, the MSC pages the SR UE, sends a call setup request message to the SR UE, allocates the media resource of the called user to the radio side, and receives the call response message of the called user, and sends a session invitation complete message to the remote end, in the message The IP address and port number of the local media are carried, and the IP is set to the IP address allocated by the P-GW for the UE. The MSC connects the media resource of the wireless side to the tunnel. The MSC receives the voice data packet of the SR UE and converts it into an IP data packet, and the destination address is set to 903. The remote media IP address and port carried in the step session invitation message are transmitted through the tunnel and sent to the remote end through the P-GW; The IP voice media is first routed to the P-GW according to the IP address of the SR UE, and the P-GW sends the voice data packet to the MSC through the tunnel connection according to the tunnel connection found by the SR UE IP, and the MSC forwards the message to the SR UE;

Step 914: The MSC notifies the media related information negotiated by the SR UE and the remote end, for example, the codec information used. If the UE does not support the currently used codec, the MSC will renegotiate the code with the remote end.

Step 915: If the media codec negotiated by the MSC and the remote end is a common codec supported by the terminal, the MSC can transmit the media related information negotiated by the MSC and the far end to the PCRF through the signaling control connection established in step 905. When the user initiates the handover by the PCRF, when the target network establishes a new bearer, it is delivered to the SR UE;

Step 916: Subsequently, the SR UE switches to the target network, and the processing flow during the handover is referred to the handover process shown in FIG. 10 or FIG. 11;

Step 917: The SR UE switches to the target network. If the IMS network is not registered, the IMS re-registration process needs to be initiated. The process is a standard process.

Steps 918-919: After the SR UE is registered, the session invitation message is sent to the IMS network, where the message carries a Session Transfer Identification (STI), the media address remains unchanged, and the signaling path is switched to the target network. This step is a standard IMS standard process and will not be described in detail here.

10 and 11 are flow chart diagrams of UE handover to E-UTRAN network signaling.

FIG. 10 illustrates a handover process initiated by the SR UE to initiate a CS domain to a PS domain. The SR UE switches to the E-UTRAN network to initiate an attach or TAU procedure to the network, and the message carries the handover finger. Handover Indicator, establishing a new bearer connection with the P-GW in the target network, and the P-GW transfers the tunnel connection of the source network to the newly created bearer connection;

Step 1001: The SR UE decides to perform radio access reselection and selects an E-UTRAN network. Step 1002: The SR UE sends an attach/TAU request message to the MME of the E-UTRAN network, where the message carries a handover indication HO Indicator, indicating that the network triggers rSRVCC Switch

Step 1003: The MME obtains user subscription data from the HSS to which the SR UE user belongs, where the user subscription data includes a PDN Context and a P-GW address allocated by the current network to the SR UE.

Step 1004: The MME sends a create bearer request message to the target S/P-GW, where the message carries the user identity identifier, HO Indicator, and PDN Context information.

Step 1005: If a PCRF is deployed in the network, the P-GW asks the PCRF whether to allow the required bearer to be created.

Step 1006: The S/P-GW allocates the bearer IP network resource, and returns a bearer response message to the MME, and creates an IP address and port number of the bearer IP network resource that is created in the bearer response message, and the IP address previously allocated for the SR UE. Address, if the session TFT and codec related information of the active session are saved in the P-GW or the PCRF, and also included in the message to the MME;

Step 1007, the MME notifies the EUTRAN to allocate the air interface resource, and transmits the session TFT and the codec related information of the active session in the P-GW or the PCRF to the SR UE;

Step 1008: After the air interface resource allocation is completed, the MME returns an update bearer request message to the S/P-GW, where the message carries the IP address and port number allocated by the EUTRAN for the user plane, and the P-GW replaces the newly established bearer connection with the source network. The tunnel is connected, and the connection with the remote end is connected, thereby connecting the media connection between the SR UE and the remote device.

11 is an embodiment in which a handover is determined by a network. The source network GERAN/UTRAN initiates a handover procedure according to a radio measurement report reported by the SR UE, and the source network notifies the target network to reserve resources, and the resource preparation is completed, and the SR UE is notified to switch to the target. The internet.

Step 1101: The source network GERAN/UTRAN decides to switch to the target EUTRAN network according to the radio quality measurement report of the UE.

Step 1102: The source network GERAN/UTRAN sends a handover request message to the MSC, where the message carries the target cell information and the source cell information.

Step 1103: The MSC selects an MME of the target network according to the target cell information, and sends the MME to the MME. And sending a CS to PS handover request message, where the message carries a user identity, PDN Context information, where the PDN context information includes: a user IP address, an APN, and a P-GW address information.

Step 1104: If the tunnel mode established by the source network is not in the GTP mode, the MME obtains the user subscription data and the related default quality of service (QoS) requirements and the like to the HSS of the user.

Step 1105: The MME sends a create bearer request to the P-GW, and the S-GW is configured to carry a handover indication (HO Indicator), a PDN Context information, a user identity identifier, and an IP address of the UE.

Step 1106: If the target network deploys the PCRF, the P-GW asks the PCRF whether to allow the required bearer to be created.

Step 1107: The P-GW and the S-GW receive the request to create a bearer, allocate the required bearer IP resource, and feed back the IP address and port number of the allocated IP resource to the MME by creating a bearer response message, if P- The GW or the PCRF saves the media information before the user switching, such as TFT and Code information, and the P-GW transmits the related information to the MME through the message;

Step 1108: The MME receives a create bearer response message, and sends a handover request message (HO Request) to the EUTRAN, where the message carries the IP address and port allocated by the P-GW for transmitting media to the EUTRAN, and switches the pre-session media information to notify the EUTRAN. Allocating air interface resources and reserving the media IP resources of the EUTRAN and the P-GW. After the E-UTRAN resources are prepared, the switch returns a handover response message to the MME, where the message encapsulates the air interface resource access parameters allocated by the EUTRAN and the session media information before the handover.

Step 1109: The MME returns a CS to PS handover response message to the MSC, where the message includes the encapsulation information in the handover response message received by the E-UTRAN.

Steps 1110-1111, the MSC returns a handover response message (HO Ack ) to the GERAN/UTRAN, where the message includes the encapsulation information in the handover response message received by the E-UTRAN, and the GERAN/UTRAN sends a handover command to the SR UE, informing the SR UE to switch to In the target network, the message carries the encapsulation information in the handover response message;

Step 1112: The SR UE switches to the radio resource reserved by the target network according to the air interface resource access parameter allocated by the E-UTRAN.

Step 1113: The SR UE accesses successfully, and sends a handover complete message to the target network E-UTRAN. The E-UTRAN returns a handover notification message to the MME, notifying the MME that the handover has been completed. Step 1114: The MME returns an update bearer request message to the S/P-GW, where the message carries the IP address and port number assigned by the EUTRAN to the user plane, P- The GW replaces the newly established bearer connection with the tunnel connection of the source network, and connects the connection with the remote end, thereby connecting the media connection between the SR UE and the remote end; Steps 1115 - 1116, the MME sends a handover complete message to the MSC, and the MSC releases Source network GERAN/UTRAN air interface resources and bearer connections between GERAN/UTRAN and MSC.

The above is only the embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. All modifications, equivalents, improvements, etc., made within the spirit and scope of the invention are intended to be included within the scope of the appended claims.

Industrial applicability

The communication system and method for enhancing the continuity of a single access voice service provided by the present invention, before the single access voice service continuity handover, the medium is anchored to the P-GW by using a tunnel connection between the enhanced MSC and the P-GW. After the handover, the session only needs to be switched from the tunnel connection to the bearer connection between the UE and the P-GW, and the connection between the remote device and the P-GW does not need to be changed, which can effectively reduce the voice in the prior art. The problem of excessive interruption time during business continuity switching greatly improves the user experience.

Claims

Claim

A method for enhancing the continuity of a single access voice service, comprising:

2. The method of claim 1 wherein:

Establishing a tunnel connection between the eMSC and the P-GW for the UE in the circuit switched domain of the source network includes:

3. The method of claim 2, wherein:

The packet data network context information further includes: an access point name APN and an APN indication; the APN indication is used to indicate whether the MSC is allowed to select a P-GW for the APN, or is used to indicate whether the APN is already in the The home network is assigned a P-GW.

4. The method according to claim 2, the method further comprising: accessing a voice service continuity service rSRVCC, and if signing, the eMSC registers with the IP multimedia subsystem IMS network instead of the UE.

5. The method according to claim 2, the method further comprising: accessing a voice service continuity service rSRVCC, if the contract is signed, the eMSC establishes a tunnel connection between the eMSC and the target packet data network gateway P-GW If the contract is not signed, the tunnel connection is not established.

The method of claim 2, wherein the establishing a tunnel connection between the eMSC and the P-GW further comprises:

The eMSC allocates the local tunnel IP resource, and sends a tunnel establishment request message to the P-GW, where the tunnel establishment request message carries the user identifier, the access point name APN, the eMSC side IP address information, and the selected target P. -GW address information;

The eMSC binds the IP address of the UE to the tunnel connection.

7. The method according to claim 6, wherein, if the tunnel connection uses a general packet radio service GPRS tunneling protocol (GTP tunnel mode), the eMSC allocates local tunnel IP resources, and sends the local tunnel IP resources to the P-GW. a tunnel establishment request message, where the tunnel establishment request message carries the user identifier, the access point name APN, the eMSC side IP address information, and the selected target P-GW address information, including:

The eMSC allocates an IP address and a port number of a default bearer and a dedicated bearer, and the eMSC

The P-GW sends a tunnel establishment request message, where the tunnel establishment request message carries the user identifier, the APN, the IP and port number of the default bearer and the dedicated bearer on the eMSC side, and the selected target P-GW address. information.

8. The method of claim 6 or 7, wherein:

The P-GW receives the tunnel establishment request message, and determines the IP address allocated to the user equipment UE as follows: determining whether the tunnel establishment request message carries the IP address of the UE, and if not, the P-GW The UE is assigned an IP address, and if so, the IP address in the message is used.

9. The method of claim 1 wherein:

When the session between the UE and the remote device is established, the eMSC receives the session establishment request initiated by the UE; the eMSC connects to the UE through the P-GW through the established tunnel connection. Establishing session communication by the remote device includes:

10. The method of claim 1, wherein

When the session between the UE and the remote device is established, the eMSC receives the session invitation message initiated by the remote device, and the eMSC passes the established tunnel connection through the P-GW. Establishing session communication between the UE and the remote device includes:

Receiving, by the eMSC, a session invitation message initiated by the remote device, where the session invitation message carries a media IP address and a port number of the remote device, where the eMSC sends a message to the UE that is called by the remote device. a call setup request message, and allocating a radio side media resource of the called UE; the eMSC receiving the call response message of the called UE, and sending a session invitation complete message to the remote device, in the session invitation completion message Carrying the media IP address and the port number of the called UE, the _e MSC sending a call setup response message to the UE, and connecting the wireless side media resource to the tunnel connection; The P-GW associates with the tunnel connection by using an IP address assigned by the P-GW to the UE; the UE is established by the MSC, the tunnel connection, the P-GW, and the remote device. Session communication from the circuit switched domain to the packet switched domain.

The method of claim 9 or 10, wherein the eMSC establishes session communication between the UE and the remote device, the method further includes: the eMSC negotiating media information with the remote device, The media information informs the local UE, and the media information includes codec information and a voice media source and destination IP address and port.

12. The method of claim 1 wherein:

During the handover of the voice service continuity between the circuit switched domain and the packet switched domain, the UE switches from the source network to the target network, and the UE initiates handover from the source network to the target network according to the radio quality change;

13. The method of claim 1 wherein:

During the handover of the voice service continuity between the circuit switched domain and the packet switched domain, the UE switches from the source network to the target network, and the source network initiates switching from the source network according to the wireless quality change of the user equipment UE. Target network

The source network sends a handover request to the mobility management entity MME of the target network; and the MME interacts with the P-GW according to the user subscription data acquired from the home network server HSS to which the user belongs, and establishes a target network. a bearer connection between the UE and the P-GW, the P-GW switching a session from the tunnel connection to between the UE and the P-GW The bearer connection.

14. The method of claim 12 or 13, wherein:

The user subscription data includes the P-GW address, the APN, and the APN indication information. The bearer connection between the UE and the P-GW in the target network includes:

And the P-GW receives the create bearer request message, associates the tunnel connection according to the handover indication and the user identifier, and allocates an IP bearer resource of the target network;

The P-GW returns a create bearer response message to the MME, where the create bearer response message carries the bearer resource IP address and port information allocated by the P-GW;

The method of claim 14, wherein, after the bearer connection between the UE and the P-GW is established, the method further includes: receiving, by the P-GW, an update sent by the MME And the P-GW is connected to the remote device and the established bearer connection between the UE and the P-GW.

16. The method of claim 12, the method further comprising: before the UE switches from the source network to the target network, the P-GW updates the current P-GW address to the HSS to which the user belongs.

17. The method of any of claims 1-7, 9, 10, 12, 13 and 16, wherein: the eMSC is a separately deployed eMSC, or a mobile switching center MSC deployed with a source mobile switching center .

18. The method of any of claims 1-7, 9, 10, 12, 13 and 16, wherein: said source network is a Global System for Mobile Communications Enhanced Data Rate Evolved Radio Access Network GERAN or Global Mobile Communication system radio access network UTRAN network; the target network is evolution Global mobile communication system radio access network E-UTRAN network.

19. A communication system for enhancing continuity of a single access voice service, comprising: a global mobile communication system enhanced data rate evolved radio access network GERAN as a source network or a global mobile communication system radio access network UTRAN network, An evolved global mobile communication system radio access network E-UTRAN network of a target network, the system further comprising an enhanced mobile switching center eMSC, a packet switched network gateway P-GW, a home network server HSS of the user home network, a mobility management entity MME The S2A interface is connected between the eMSC and the P-GW;

The MME is configured to establish, according to the target network, a bearer connection between the UE and the P-GW when the UE is handed over from the source network to the target network;

20. The communication system according to claim 19, wherein the S2a interface between the eMSC and the P-GW supports a GPRS Tunneling Protocol GTP and/or a Proxy Mobile IP Protocol PMIP.

21. The communication system according to claim 19, wherein: the P-GW is selected from the network PDN context information.

22. The communication system of claim 19, wherein:

The eMSC is configured to establish a tunnel connection between the eMSC and the P-GW when receiving a user location update request message, a user attach request message, or a call setup message in the source network.

23. The communication system of claim 19, wherein:

The eMSC is further configured to: after receiving the session establishment request of the local end of the UE or the session invitation message of the remote device, send the IP address allocated by the P-GW to the UE to the remote device. Address.

The communication system of claim 19, the communication system further comprising a source mobile switching center, wherein the eMSC is further configured to: after receiving the handover preparation request message sent by the source mobile switching center, to the handover The target cell in the preparation request message forwards the handover preparation request message, so that the target cell forwards the handover preparation request message to the target MME; the MME is further configured to notify the target network to allocate resources; or directly return a response. And indicating that the UE accesses the target network, and implements handover by using a bearer connection between the UE established by the target network and the P-GW.

25. The communication system of claim 24, wherein:

The MME is further configured to receive a handover request message of the eMSC, create a default bearer, or initiate a single access voice service user registration to the eMSC after the UE completes the tracking area update process.