CN102244910B

CN102244910B - Communication system and method for enhancing single radio voice call service continuity

Info

Publication number: CN102244910B
Application number: CN201010169829.6A
Authority: CN
Inventors: 陶全军; 谢振华; 游世林; 王鸿彦
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2010-05-10
Filing date: 2010-05-10
Publication date: 2014-12-10
Anticipated expiration: 2030-05-10
Also published as: WO2011140888A1; CN102244910A

Abstract

The invention discloses a communication system and a method for enhancing single radio voice call service continuity. According to the method, in a circuit switch domain of a source network, a tunnel connection between an enhanced mobile switch center (eMSC) and a packet data network gateway (P-GW) is established for UE; when a conversation is established, the eMSC passes through the P-GW and establishes conversation communication from a circuit switch domain to a packet switch domain for the UE and remote equipment by the established tunnel connection; during a switching process for the voice call service continuity, a bearing connection between the UE and the P-GW is established in the circuit switch domain; A bearing connection, which is between the UE and the P-GW, and the remote equipment are connected by the P-GW in order to establish conversation communication from the circuit switch domain to the packet switch domain for the UE and the remote equipment. According to the invention, after the switching operation, conversation is switched from the tunnel connection to the bearing connection between the UE and the P-GW, so that a problem that the interruption time is too long during the continuous switching operation can be effectively solved.

Description

A kind of communication system and method that strengthens single voice call service continuity

Technical field

The present invention relates to mobile communication technology field, relate in particular to a kind of communication system and method that strengthens single voice call service continuity.

Background technology

In order to keep 3-G (Generation Three mobile communication system) standardization project (3rd Generation PartnershipProject, referred to as 3GPP) in the strong competitiveness of moving communicating field, 3GPP is just endeavouring research at present to packet switched core network (Packet Switched Core, referred to as PS Core) and global system for mobile communications wireless access network (Universal Mobile Telecommunication System RadioAccess Network, referred to as UTRAN) evolution, object is that the PS Core (being called for short EPC) that makes evolution can provide higher transmission rate, shorter transmission delay, and support E-UTRAN (EvolvedUTRAN, the UTRAN of evolution), GERAN (GSM EDGE radio access network, GSMEDGE wireless access network, wherein GSM is the abbreviation of Global System for Mobile communications, it is global system for mobile communications, EDGE is the abbreviation of Enhanced Data Rate for GSM Evolution, be enhanced data rates for gsm evolution technology), UTRAN, WLAN (Wireless LocalAreaNetwork, WLAN (wireless local area network)) mobile management and between the access network of other non-3GPP.The mobile communication system of this evolution is called as the grouping domain system (Evolved Packet System, referred to as EPS) of evolution.

EPS system architecture as shown in Figure 1, comprising:

E-UTRAN, for realizing all radio functions relevant with evolvement network;

Mobile management entity (Mobility Management Entity, MME) is responsible for chain of command mobile management, comprises user's context and mobile status management, distributing user temporary identity sign etc.;

Service gateway entity (Servering Gateway, S-GW), is a user entity, is responsible for user face data route processing;

Packet data network gateway (Packet Data Network Gateway is called for short PDN GW or P-GW), is responsible for the gateway function that UE accesses PDN (Packet Data Network, Packet Data Network).P-GW and S-GW may close and be located in a physical entity;

SGSN (SGSN:Serving GPRS Supporting Node) is Serving GPRS Support Node;

Charging and policy control entity (Policy and Charging Rule Function, PCRF) determine for policy control and flow based charging is controlled function;

Home network server (Home Subsriber Server, HSS) is for storing user subscription information.

Be illustrated in figure 2 existing single access voice continuity (Single Radio Voice Call Continuity, SRVCC) system architecture diagram.Wherein UTRAN/GERAN is mainly used in as 3G/2G circuit switching (Circuit Switch is called for short CS) territory network insertion; Source mobile switching centre (Source Mobile SwitchCenter, Source MSC) is mainly used in user in source circuit switching network user's face and signaling function of exchange; Strengthen (the enhanced Mobile Switch Center of mobile switching centre, be called for short eMSC), be used for helping Single Radio UE to complete CS territory and packet-switched domain (Packet Switch, abbreviation PS) voice continuity between, this network element can be deployed as same network element with Source MSC.

IP Multimedia System (IP Multimedia Core Network Subsystem, be called for short IMS) be by third generation partner program (3rd Generation Partnership Project, abbreviation 3GPP) a kind of IP-based network architecture proposing, built the opening of and service environment flexibly, support multimedia application, can provide abundant multimedia service for user.

In IMS business system, key-course is separated with operation layer, and key-course does not provide concrete business, and the functions such as necessary triggering, route, charging are only provided to operation layer.

In key-course, business triggering and control function are that CSCF (Call Session ControlFunction is called for short CSCF) completes.CSCF is divided into: Proxy Call Session Control Function (Proxy-CSCF, abbreviation P-CSCF), query call conversation control function (Interrogating-CSCF, be called for short I-CSCF) and service call conversation control function (Serving-CSCF, be called for short S-CSCF) three types, that wherein take the main responsibility is S-CSCF, and I-CSCF is optional.

Operation layer is to be comprised of a series of application servers (Application Server, be called for short AS), and concrete business service can be provided, and AS can be entity independently, also may reside in S-CSCF.

Because single voice call service continuity key technology is mainly CS and the internetwork signaling of PS and user interaction process, for simplified characterization, network element relevant in IMS network, be referred to as IMS network element here.

Fig. 3 is that existing single voice call service continuity is switched to the flow chart of packet-switched domain (CS to PS) from circuit commutative field, described SR UE and at first in circuit-domain network and remote equipment, set up session, signaling and business are anchored on IP Multimedia System (IMS).If there is network, switch, the SRUE raw single voice call service continuity process of supervention after the meeting, SR UE, from LTE network insertion, need re-establish with the media of remote equipment and be connected, and to keep the continuous process of session, this process comprises the steps:

301, the wireless measurement report that the network based SR UE of GERAN/UTRAN reports, determines to initiate to switch to E-UTRAN;

302, GERAN/UTRAN sends handover request message (HO Required) to Source MSC, carries the Target Cell Identifier that points to target E-UTRAN network in message;

303, Source MSC sends to switch to eMSC according to Target Cell Identifier in message and prepares message (Prepare HO Request), and notification target network switches;

304, there are not Internet resources in eMSC judgement SR UE in target E-UTRAN network, judges whether target E-UTRAN network possesses the Internet resources that can offer user UE, and eMSC can inquire about to objective network MME, or inquires about at device interior.

305, eMSC returns to switch to Source MSC and prepares response message (Prepare HOResponse), in message, carry network insertion indication (Networl Access Indicator, NAI), by this network insertion indication, notify SR UE in E-UTRAN network insertion New-deployed Network resource, to complete switching;

306, Source MSC returns to handover acknowledge message (HOResponse) to source GERAN/UTRAN network, carries network insertion indication in message;

307, source GERAN/UTRAN transmission switching command (HO Command) notice SR UE switches.In message, carry network insertion indication, indication UE is linked into E-UTRAN network, and New-deployed Network resource completes switching;

308, SR UE receives switching command, according to network insertion indication NAI, is switched to E-UTRAN network, and initiates standard-track area update flow process (Tracking Area Update, TAU);

Because SR UE is switched to E-UTRAN network from GERAN/UTRAN network, at this time between SRUE and GERAN/UTRAN, user's face is connected and ruptures, and service bearer in E-UTRAN network is not yet set up, will be temporarily between SR UR and remote equipment cannot communication, thereby single voice call service continuity will be interrupted, cause the speech communication meeting between user equipment (UE) and remote equipment that temporary transient voice interruption occurs.

309, SR UE sets up required carrying at E-UTRAN network, and process of establishing is the PS loading establishing process of standard, is not described in detail here;

310, after carrying is set up, SR UE registers to the IMS network of user ascription area;

311, succeed in registration, SR UE sends session invitation message (INVITE) to user ascription area IMS network, message is carried static configuration at Session Hand-off indication (the Session TransferIndication of UE inside, STI), this session of indication IMS network element is for business continuance (ServiceContinuity, SC).IMS network element is by upgrading the flow process of remote equipment, original IP media connected by remote equipment, be connected to Source MSC to be updated to SR UE and to be directly connected, and centre may be by way of some EPS network elements and other network equipments.This step is the business continuance SC flow process of standard, does not launch here carefully to state;

312, after the flow process of remote equipment is updated successfully, IMS network element returns success message (200OK) to SR UE.

SR UE receives after 200Ok message, recover and remote equipment between speech communication, complete SR UE and switch voice continuity between CS territory and PS territory.

From the flow process shown in above-mentioned Fig. 3, in existing single voice call service continuity implementation method, in step 310～312, need to carry out and upgrade operation remote equipment, and the time delay that IP Multimedia System IMS signaling is transmitted is long, this will cause the dropped calls time excessive, even can have influence on user's normal communication, cause user experience to decline.

Summary of the invention

Technical problem to be solved by this invention is, a kind of communication system and method that strengthens single voice call service continuity is provided, in order to overcome the excessive deficiency that waits of handover delay of existing single voice call service continuity technology, solve single voice call service continuity and cause the long problem of voice interruption because remote equipment upgrades.

In order to address the above problem, the present invention proposes a kind of method that strengthens single voice call service continuity, comprising:

In the circuit commutative field of source network, for user equipment (UE), setting up the enhancing eMSC of mobile switching centre is connected with the tunnel between packet switching network gateway P-GW, during the session establishment of described UE and remote equipment, described eMSC connects through described packet switching network gateway P-GW by the described tunnel of having set up, for UE and remote equipment are set up circuit commutative field to the session communication of packet-switched domain;

At circuit commutative field, to the voice business continuity handoff procedure of packet-switched domain, at the circuit commutative field of objective network, set up the bearer connection between UE and packet switching network gateway P-GW; Described packet switching network gateway P-GW is connected with the bearer connection between packet switching network gateway P-GW described UE with remote equipment, at objective network, be that UE and described remote equipment are set up circuit commutative field to the session communication of packet-switched domain.

The described enhancing eMSC of mobile switching centre is when user equipment (UE) is attached to source network, or while receiving position updating request or setup requests in source network, set up the enhancing eMSC of mobile switching centre and be connected with the tunnel between packet switching network gateway P-GW:

Strengthen the eMSC of mobile switching centre and obtain user contracting data and Packet Data Network's contextual information to the home network server HSS under user, described eMSC is according to the contextual information select target packet data network gateway P-GW of Packet Data Network, set up described eMSC and be connected with the tunnel between targeted packets data network gateway P-GW, described Packet Data Network contextual information comprises sign and/or the address of targeted packets data network gateway P-GW.

Described Packet Data Network contextual information also comprises: APN APN, and APN indication; Described APN indication is used to indicate and whether allows described MSC is that described APN APN selects packet data network gateway P-GW, or is used to indicate described APN APN and whether at home network, has distributed P-GW.

The described enhancing eMSC of mobile switching centre judges according to the user contracting data obtaining whether described user is signing and returns to single voice call service continuity business rSRVCC, if signing, described eMSC replaces user equipment (UE) to register to IP Multimedia System IMS network.

The described enhancing eMSC of mobile switching centre judges according to the user contracting data obtaining whether described user is signing and returns to single voice call service continuity business rSRVCC, if signing, described MSC sets up described eMSC and is connected with the tunnel between targeted packets data network gateway P-GW, if not signing, do not set up described tunnel and connect.

Described foundation strengthens the step that the eMSC of mobile switching centre is connected with tunnel between packet data network gateway P-GW and is specifically divided into again:

Described eMSC distributes local terminal tunnel IP resource, sends tunnel set up request message to P-GW, and tunnel is set up in request message and carried user ID, APN APN, eMSC side IP address information and selected object P-GW address information;

Described P-GW receives that tunnel sets up request message, determine the IP address of distributing to user equipment (UE), distribute tunnel resource, return to tunnel and set up request-reply message to described eMSC, described tunnel is set up in request-reply message and is carried IP address and the tunnel address information of distributing into described UE, completes tunnel and sets up;

The IP address that described eMSC binds described UE is connected with described tunnel.

If connecting, described tunnel adopts general packet radio service gprs tunnel protocol (GTP tunnel mode), IP and port numbers that the described enhancing eMSC of mobile switching centre distributes default bearing and dedicated bearer, described eMSC sends tunnel to P-GW and sets up request message, tunnel is set up and in request message, is carried described user ID, APN APN, the default bearing of described eMSC side and the IP of dedicated bearer and port numbers, and selected object P-GW address information.

Described P-GW receives that tunnel sets up request message, the mode of determining the IP address distribute to user equipment (UE) is: judge that tunnel sets up the IP address of whether carrying UE in request message, if do not had, described P-GW is this user assignment IP address, if have, use the IP address in described message.

During session establishment between described UE and remote equipment, refer to that described eMSC receives the session establishment request that described UE initiates, it is that the step that UE and described remote equipment are set up session communication comprises that described eMSC connects through described packet data network gateway P-GW by the described tunnel of having set up:

Described eMSC distributing user wireless side media resource, sends session invitation message, media IP address and the port numbers of in session invitation message, carrying UE to remote equipment;

When receiving the session that remote equipment returns, described eMSC completes message, described session completes media IP address and the port numbers of the remote equipment carrying in message, described eMSC sends call setup response message to described UE, connects described wireless side media resource and is connected with described tunnel;

Described P-GW is that the IP address that described UE distributes is carried out associated with tunnel connection by P-GW; Described UE sets up circuit commutative field to the session communication of packet-switched domain through described MSC, the connection of described tunnel, described P-GW and described remote equipment.

During session establishment between described user equipment (UE) and remote equipment, refer to that described eMSC receives the session invitation request that described remote equipment is initiated, it is that the step that UE and described remote equipment are set up session communication comprises that described MSC connects through described packet data network gateway P-GW by the described tunnel of having set up:

Described eMSC receives the session invitation request message that remote equipment is initiated, in described session invitation request message, carry media IP address and the port numbers of remote equipment, described eMSC sends call setup request message to the UE being called out by far-end, and distributes the wireless side media resource of called UE;

Described eMSC receives the call answering message of called UE, to remote equipment, send session invitation and complete message, in message, carry media IP address and the port numbers of called UE, described MSC sends call setup response message to described UE, connects described wireless side media resource and is connected with described tunnel;

Described eMSC is UE and described remote equipment while setting up session communication, also consults media information with remote equipment, and by described media information notice local terminal user equipment (UE), described media information comprises coding/decoding information and voice medium source and destination IP address and port.

Described user equipment (UE) is switched to objective network from source network, refers to by user equipment (UE) and changes and initiate to be switched to objective network from source network according to wireless quality; Described UE adheres to or tracking area update request message to the mobile management entity MME transmission of described objective network, carries and switch indication in message; Described MME carries out alternately according to the user contracting data and the described P-GW that obtain from user attaching network HSS, set up described UE in objective network and the bearer connection between P-GW, P-GW connects session to be switched to the bearer connection between described UE and P-GW by tunnel.

Described user equipment (UE) is switched to objective network from source network, refers to by source network and changes and initiate to be switched to objective network from source network according to the wireless quality of user equipment (UE); Described source network sends handover request to the mobile management entity MME of described objective network; Described MME carries out alternately according to the user contracting data and the described P-GW that obtain from user attaching network HSS, set up described UE in objective network and the bearer connection between P-GW, P-GW connects session to be switched to the bearer connection between described UE and P-GW by tunnel.

Described user contracting data comprises described P-GW address and APN, APN indication information; Described MME sends and sets up carrying request to described P-GW by way of gateway S-GW, sets up in bearing request message and carries and switch indication, user ID, APN and P-GW address; Described P-GW receives carrying foundation request, and according to switching indication and described user ID, associated described tunnel connects, and is dispensed to the IP bearing resource of described objective network; Described P-GW returns to carrying and sets up response message to MME, and bearing resource IP address and the port information that carries described P-GW distribution in response message set up in carrying; Described MME notifies described objective network to set up the bearer connection between described UE and P-GW.

Described method is also included in after carrying foundation, and described P-GW receives more new bearer request of MME, according to described user ID and the associated described tunnel of switching indication, is connected, and described P-GW connects the bearer connection between remote equipment and the described UE having set up and P-GW.

Described method is further included in before switching, and described P-GW upgrades current P-GW address to the HSS under described user.

The described enhancing eMSC of mobile switching centre is the eMSC of enhancing mobile switching centre disposing separately, or Yu Yuan mobile switching centre is deployed as moving exchanging center MSC together.

Described source network is global system for mobile communications enhanced data rates evolution wireless access network GERAN/ global system for mobile communications wireless access network UTRAN network; Described objective network is the global system for mobile communications wireless access network E-UTRAN network of evolution.

The present invention also provides a kind of communication system that strengthens single voice call service continuity, comprise: as the GERAN/UTRAN network of source network, E-UTRAN network as objective network, user equipment (UE) switches to objective network from source network, it is characterized in that: described system also comprises the enhancing eMSC of mobile switching centre, packet switching network gateway P-GW, user attaching network HSS, mobile management entity MME, is connected with S2a interface between described eMSC and P-GW;

In the circuit commutative field of source network, strengthening the eMSC of mobile switching centre and be user equipment (UE) sets up eMSC and is connected with the tunnel between P-GW, during session establishment, it is that UE and remote equipment are set up circuit commutative field to the session communication of packet-switched domain that described eMSC connects through described pass P-GW by the described tunnel of having set up;

When user equipment (UE) is switched to objective network from source network, described MME is according to the handover request of described eMSC, according to the user contracting data and the described P-GW that obtain from user attaching network HSS, carry out alternately, at the circuit commutative field of objective network, setting up the bearer connection between UE and P-GW;

Described P-GW is connected with the bearer connection between packet switching network gateway P-GW described UE with remote equipment, at objective network, be that UE and described remote equipment are set up circuit commutative field to the session communication of packet-switched domain.

S2a interface between described eMSC and P-GW is supported GPRS Tunnel Protocol GTP and/or proxy mobile IP protocol PMIP.

Described eMSC can be according to selecting P-GW in the grouped data network PDN contextual information the user contracting data obtaining from user attaching network HSS.

Described eMSC is while receiving user position update/Attach Request message or call setup message in source network, sets up eMSC and is connected with the tunnel between P-GW.

Described eMSC is after receiving the session invitation message of the session establishment request of UE local terminal or remote equipment, and eMSC sends to far-end the IP address that P-GW is user assignment.

Described communication system further comprises the Source MSC of source mobile switching centre, described eMSC receives after the handover preparation request message of Source MSC transmission, according to Target cell in handover preparation request message, forward handover request message to target MME, notification target network allocation resource; Or directly return to response message, indication UE is linked into objective network, utilize UE and the bearer connection between P-GW at objective network, set up to realize switching.

Mobile management entity MME is received the handover request message of eMSC, creates default bearer or MME and to eMSC, initiate single access speech business user registration after UE TAU completes.

Prior art is anchored on IMS system by conversation media, thereby need in execution voice business continuity handoff procedure that remote equipment is carried out to flow process renewal, causes test long.Communication system and the method for the single voice call service continuity of enhancing of the present invention, before single voice call service continuity switches, utilize enhanced MSC to be connected media are anchored on to P-GW with tunnel between P-GW, after switching, only need session to connect and switch to the bearer connection between UE and P-GW from tunnel, between remote equipment and P-GW, be connected without change, when this just can effectively reduce in prior art voice business continuity and switches break period long problem, greatly improve user's experience.

Accompanying drawing explanation

Fig. 1 is the system architecture diagram of the grouping domain system EPS of evolution;

Fig. 2 is existing single voice call service continuity SRVCC system architecture diagram;

Fig. 3 is that existing single voice call service continuity is switched to the flow chart in PS territory from CS territory;

Fig. 4 is the system architecture schematic diagram of the single voice call service continuity of enhancing of the present invention;

Fig. 5 is the voice medium path schematic diagram of the single voice call service continuity of enhancing of the present invention;

Fig. 6 is the signaling process figure of embodiments of the invention one;

Fig. 7 is the signaling process figure of embodiments of the invention two;

Fig. 8 is the signaling process figure of embodiments of the invention three;

Fig. 9 is the signaling process figure of embodiments of the invention four;

Figure 10 is that the UE that UE initiates is switched to E-UTRAN network signal flow process figure;

Figure 11 is that the UE that network side is initiated is switched to E-UTRAN network signal flow process figure.

Embodiment

For making the object, technical solutions and advantages of the present invention clearer, below in conjunction with accompanying drawing, the present invention is described in further detail.

Core concept of the present invention is, for strengthening by circuit commutative field (CS), to packet-switched domain (PS) handoff procedure, singly access voice continuity, while setting up session in circuit commutative field (CS), setting up MSC is connected with the tunnel between P-GW, utilize this tunnel to connect carrying session, when session switches to packet-switched domain (PS), set up the bearer connection between the middle UE of packet-switched domain (PS) and P-GW, by P-GW, session is connected and switched to the bearer connection between UE and P-GW by tunnel, P-GW is connected the bearer connection between this P-GW with remote equipment, set up session communication.

In prior art, after switching, set up bearer connection, IMS system need to be upgraded the session flow process of remote equipment, and in the present invention, owing to being that session is connected to carrying by tunnel before switching, with the Session Anchor of remote equipment at P-GW, thereby, during switching, only need tunnel to connect and to switch to the carrying between P-GW and UE, for being connected without change between P-GW and remote equipment, thereby shortened greatly possible switching time, can effectively strengthen single voice call service continuity.

Below in conjunction with drawings and Examples, describe the present invention.

Fig. 4 is the system architecture schematic diagram of the single voice call service continuity of enhancing of the present invention, compares with the existing system framework shown in Fig. 2, and main interface has increased S2a mouth between eMSC and S/P-GW newly.On Network Element Function, be mainly concerned with the change of eMSC and MME.Wherein:

(1) the main newly-increased function of the eMSC of evolution mobile switching centre, comprising:

S2a interface between a.eMSC support and S/P-GW, supports GPRS Tunnel Protocol (GPRSTunnel Protocol, GTP) or proxy mobile IP protocol (Proxy Mobile IP, PMIP);

B.eMSC can select S/P-GW according to the contextual information of the signing grouped data network PDN of user;

C.eMSC receives user position update/Attach Request message or call setup message, set up with S/P-GW between tunnel be connected.

D.eMSC receives the request of local terminal session establishment or far-end session invitation message, and the media IP address that eMSC returns to far-end is set to the IP address that P-GW is user assignment;

E.eMSC receives that the handover preparation request message that Source MSC sends can be transmitted to target MME message according to Target cell in message, notification target network allocation resource; Or directly return to response message, indication UE is linked into E-UTRAN network, and newly-built carrying is for switching;

(2) the main what's new of mobile management entity MME is: the CS toPS handover request message when MME receives eMSC, creates default bearer or MME and to eMSC, initiate Single Radio registration after UE TAU completes.

Fig. 5 is the voice medium path schematic diagram of the single voice call service continuity of enhancing of the present invention, before switching, SR UE accesses in GERAN/UTRAN network, and initiate speech business with remote equipment, service path is anchored on the IMS network of user attaching, before switching, media path is: SR UE is connected to MSC by GERAN/UTRAN circuit-domain network, and connect and anchor to P-GW by tunnel, then be connected with far-end by IMS network.SR UE initiates to switch, and SR UE is switched to EUTRAN network, and the media path after switching is: between SR UE and P-GW, set up EPS bearer connection, P-GW connects SR UE and remote equipment.Path schematic diagram is visible thus, and before switching, media are connected and are anchored on P-GW by tunnel, switches between the EPS bearer connection occurring over just after tunnel connection and switching, for P-GW, does not change with being connected of remote equipment.

Fig. 6 is embodiments of the invention one, single access user equipment SR UE is described in GERAN/UTRAN network attachment, MSC obtains user data to user's HSS, signing single access service continuity (the return Single Radio Voice Call Continuity that returns of judgement user, rSRVCC) business, and according to Packet Data Network's contextual information in user data, select target P-GW, set up with P-GW between tunnel be connected, when SR UE makes a call, MSC voice medium is connected with remote equipment and is carried out communication by tunnel, follow-up SR UE causes source network wireless quality variation because of mobile or other reasons, by UE or network, initiate handoff procedure, speech business is switched to EUTRAN network, the detailed process switching is as follows:

601, SR UE initiates access procedure at GERAN/UTRAN network, MSC also obtains user contracting data from HSS, in data, may comprise rSRVCC CAMEL-Subscription-Information and rSRVCC PDNContext, the described contextual information PDN Context of Packet Data Network comprises: target P-GW sign/address or APN indication, APN (Access PointName, APN), wherein, APN indication is used to indicate and whether allows MSC is that APN selects P-GW, or whether APN distributes P-GW at home network;

602, MSC judgement user is rSRVCC user, MSC replaces UE to initiate IMS register flow path, this flow process is 3GPP normal process, be not described in detail herein, MSC judgement user can judge by the subscription data obtaining according to 601 steps for rSRVCC user, or can judge according to number section of user identity number;

603, SR UE makes a call, and session between request foundation and remote equipment, sends setup requests to MSC;

604, MSC is according to PDN Context select target P-GW, if comprise the address of P-GW in PDN Context, MSC select in PDN Context P-GW, if do not comprise P-GW address in P-GW Context, MSC indicates and selects according to APN, wherein: if APN indication allows MSC to select, MSC runs strategy according to the static configuration of oneself or utilization business, selects a local P-GW; If indication home network has configured P-GW, MSC obtains and distributes P-GW address to user attaching net;

If do not comprise PDN Context in user contracting data, MSC is according to the static configuration of oneself or use business to run strategy, selects a local P-GW;

If 605 network design PCRF, MSC may need the signaling control connection between foundation and PCRF, and this step is optional step;

606, MSC sends tunnel to target S/P-GW and sets up request, tunnel is set up and in request message, is carried rSRVCC APN, P-GW address, SR UE identify label, also comprise some other downlink tunnel security information, if tunnel adopts GTP tunnel mode, in message, also need to carry MSC for transmitting GTP tunnel IP address and port numbers;

If 607 network design PCRF, P-GW initiates IP and connects session establishment program, and P-GW is provided for identifying session and associated 605 step signaling control connections to PCRF, and this step is optional step.

608, P-GW judges that tunnel sets up the IP address of whether carrying UE in request message, if do not had, P-GW is SR UE distributing IP address; P-GW distributes tunnel IP resource;

609, P-GW sends and upgrades P-GW request message to the HSS under SR UE, and the address information of carrying P-GW in message, if the switching mode of being initiated by network shown in network support Figure 11 does not need this step;

610, S/P-GW returns and sets up tunnel acknowledgment message to MSC, in message, carrying P-GW is IP address and the S/P-GW side tunnel IP resource that SRUE distributes, if adopt GTP tunnel mode, P-GW may create default bearer tunnel and dedicated voice bearing tunnel, and the IP address of MSC binding SR UE is connected with tunnel;

Step 604-610 also can complete before step 603;

611, MSC distributing user wireless side media resource, sends session invitation message to far-end, carries local terminal media IP address and port numbers in message, and it is the IP address that SR UE distributes that described IP address is set to P-GW.

612-613, MSC receive that far-end session completes message, and MSC sends call setup response message to SR UE, connect wireless side media resource and are connected with tunnel.MSC receives the VoP of described UE, is converted to IP packet, and distant end media IP address and port that destination address is set to carry in session response message, connect by tunnel, through P-GW, sends to remote equipment; First the ip voice media of remote equipment route to P-GW according to the IP address of described UE, P-GW finds tunnel to connect according to described UE IP address, IP packet is connected and sent to described MSC by tunnel, be transmitted to described UE after being converted to VoP by described MSC;

614, the media relevant information that MSC notice SR UE and far-end are consulted, as the coding/decoding information adopting, if UE does not support the encoding and decoding of current employing, MSC will consult encoding and decoding again with far-end;

If the media encoding and decoding that 615 MSC and far-end are consulted are general encoding and decoding that a terminal is all supported, the signaling control connection that MSC can set up by 605 steps, the media relevant information of MSC and far-end negotiation is passed to PCRF, by PCRF when user switches, when objective network is set up new bearer, pass to SR UE.

616, follow-up, SR UE is switched to objective network, and handling process during switching is referring to the switching flow shown in Figure 10 or Figure 11;

617, SR UE is switched to objective network, if not in IMS network registry mistake, need to initiate IMS and re-register flow process, this flow process is normal process;

After 618-619, SR UE have registered, to IMS network, send session invitation message, carry Session Hand-off sign (Session Transfer Indentification, STI) in message, media address remains unchanged, and signaling paths is switched to objective network.This step is standard I MS normal process, is not described in detail here.

Fig. 7 is the embodiment of the present invention two, is with the main distinction of embodiment mono-, and eMSC what's new is peeled off out from traditional MSC, disposes separately eMSC.When SR UE adheres to or position upgrades, Source MSC is first routed to eMSC positional information, pass to again HSS, eMSC obtains the signing rSRVCC CAMEL-Subscription-Information of SR UE, and foundation is connected with the tunnel of object P-GW, when SR UE makes a call, Source MSC is first routed to eMSC calling out, and eMSC is calling out from tunnel connection route to remote equipment.

701, SR UE initiates access procedure at GERAN/UTRAN network, to Source MSC, sends Attach Request message, and Source MSC sends location update request message to the HSS under user, and this location update request message is by way of eMSC;

702, eMSC forwards described location update request message to HSS;

703-704, HSS upgrade response message to eMSC home position, eMSC receives position update response information, from position update response information, obtain the signing rSRVCC information of SR UE, this packets of information is containing rSRVCC CAMEL-Subscription-Information and rSRVCC PDN Context (Packet Data Network's context);

705, eMSC home position upgrades response message to Source MSC;

706, eMSC judgement user is rSRVCC user, replace UE to initiate IMS register flow path, this flow process is 3GPP normal process, here be not described in detail, eMSC judgement user can judge by the subscription data obtaining according to 704 steps for rSRVCC user, or can judge according to number section of user identity number;

When 707, SR UE makes a call, to Source MSC, send call setup request message;

708, Souce MSC routes calls to eMSC;

709, eMSC is according to PDN Context select target P-GW, if comprise the address of P-GW in PDN Context, eMSC select in PDN Context P-GW, if do not comprise P-GW address in P-GW Context, eMSC indicates and selects according to APN, wherein: if APN indication allows eMSC to select, eMSC runs strategy according to the static configuration of oneself or utilization business, selects a local P-GW; If indication home network has configured P-GW, eMSC obtains and distributes P-GW address to user attaching net;

If do not comprise PDN Context in user contracting data, eMSC is according to the static configuration of oneself or use business to run strategy, selects a local P-GW;

If 710 network design PCRF, eMSC may need the signaling control connection between foundation and PCRF, and this step is optional step;

711, eMSC sends tunnel to target S/P-GW and sets up request, tunnel is set up and in request message, is carried rSRVCC APN, P-GW address, SR UE identify label, also comprise some other downlink tunnel security information, if tunnel adopts GTP tunnel mode, in message, also need to carry eMSC for transmitting GTP tunnel IP address and port numbers;

If 712 network design PCRF, P-GW initiates IP and connects session establishment program, and P-GW is provided for identifying the signaling control connection of session and associated 710 steps to PCRF, and this step is optional step.

713, P-GW judges that tunnel sets up the IP address of whether carrying UE in request message, if do not had, P-GW is SR UE distributing IP address; P-GW distributes tunnel IP resource;

714, P-GW sends and upgrades P-GW request message to the HSS under SR UE, and the address information of carrying P-GW in message, if the switching mode of being initiated by network shown in network support Figure 11 does not need this step;

715, S/P-GW returns and sets up tunnel acknowledgment message to eMSC, in message, carrying P-GW is IP address and the S/P-GW side tunnel IP resource that SRUE distributes, if adopt GTP tunnel mode, P-GW may create default bearer tunnel and dedicated voice bearing tunnel, and the IP address of eMSC binding SR UE is connected with tunnel;

Step 709-715 also can complete before step 707;

716, eMSC distributing user wireless side media resource, sends session invitation message to far-end, carries local terminal media IP address and port numbers in message, and it is the IP address that SR UE distributes that described IP address is set to P-GW.

717, eMSC receives that far-end session completes message, and session completes message and carries the IP address that P-GW is SR UE distribution.

718, eMSC receives that session completes message, to Source MSC return address, completes message;

719, Source MSC sends call setup response message to SR UE, connects wireless side media resource and is connected with tunnel.

The media relevant information that 720-721, eMSC notice SR UE and far-end are consulted, as the coding/decoding information adopting, if UE does not support the encoding and decoding of current employing, MSC will consult encoding and decoding again with far-end; If the media encoding and decoding that eMSC and far-end are consulted are general encoding and decoding that a terminal is all supported, the signaling control connection that eMSC can set up by 707 steps, the media relevant information of MSC and far-end negotiation is passed to PCRF, by PCRF when user switches, when objective network is set up new bearer, pass to SR UE.

After session establishment, eMSC receives the VoP of described UE, is converted to IP packet, and distant end media IP address and port that destination address is set to carry in session response message, connect by tunnel, through P-GW, sends to remote equipment; First the ip voice media of remote equipment route to P-GW according to the IP address of described UE, P-GW finds tunnel to connect according to described UE IP address, IP packet is connected and sent to described eMSC by tunnel, be transmitted to described UE after being converted to VoP by described eMSC;

722, follow-up, SR UE is switched to objective network, and handling process during switching is referring to the switching flow shown in Figure 10 or Figure 11;

723, SR UE is switched to objective network, if not in IMS network registry mistake, need to initiate IMS and re-register flow process, this flow process is normal process;

After 724-725, SR UE have registered, to IMS network, send session invitation message, carry Session Hand-off sign (Session Transfer Indentification, STI) in message, media address remains unchanged, and signaling paths is switched to objective network.This step is standard I MS normal process, is not described in detail here.

Fig. 8 is the invention process three, is with the difference of embodiment mono-, and the tunnel style of the present embodiment adopts GTP tunnel mode, creates default bearer when user adheres to, receives call request application-specific carrying transmission voice again;

801, SR UE initiates access procedure at GERAN/UTRAN network, MSC also obtains user contracting data from HSS, in user contracting data, may comprise rSRVCC CAMEL-Subscription-Information and rSRVCCPDN Context, the described contextual information PDN Context of Packet Data Network comprises: target P-GW sign/address or APN indication, APN (Access Point Name, APN), wherein, APN indication is used to indicate and whether allows MSC is that APN selects P-GW, or whether APN distributes P-GW at home network;

802, MSC is according to PDN Context select target P-GW, if comprise the address of P-GW in PDN Context, MSC select in PDN Context P-GW, if do not comprise P-GW address in P-GW Context, MSC indicates and selects according to APN, wherein: if APN indication allows MSC to select, MSC runs strategy according to the static configuration of oneself or utilization business, selects a local P-GW; If indication home network has configured P-GW, MSC obtains and distributes P-GW address to user attaching net;

803, MSC simulation S-GW sends and creates default bearer request to P-GW, carries user ID in message, and MSC is IP address and the port numbers that default bearer distributes, P-GW address, the information such as bearing identification and APN;

If the dynamic PCRF of 804 network design, P-GW obtains user's strategy and charging control criterion to PCRF, and judges whether to allow user to set up ask carrying;

805, P-GW is SR UE distributing IP address, and user's face IP address and the port numbers of default bearer;

806, P-GW returns to default bearer response message to MSC, carries user's face IP address and the port numbers of default bearer in message;

807, MSC judgement user is rSRVCC user, MSC replaces UE to initiate IMS register flow path, this flow process is 3GPP normal process, be not described in detail herein, MSC judgement user can judge by the subscription data obtaining according to 801 steps for rSRVCC user, or can judge according to number section of user identity number;

808, the SR UE request of making a call, sends call setup request message to MSC;

809, MSC simulation S-GW sends and sets up dedicated bearer request message to P-GW, carries bearer connection sign (Linked Bearer Id, LBI), QoS, and traffic flow template (Traffic FlowTemplate, TFT) in message.LBI is mainly used in the default bearer that associated 803 to 806 steps are set up; QoS is used for notifying P-GW resource requirement quality requirement;

If 810 dispose dynamic PCRF, P-GW notifies PCRF, by PCRF, judges whether to allow SR UE application bearing resource;

If 811 allow to set up, P-GW distributes required bearing resource, to MSC, returns and sets up dedicated bearer request-reply message, carries and distribute P-GW side carrying IP address and port numbers in message;

812, MSC distributing user wireless side media resource, sends session invitation message to far-end, carries local terminal media IP address and port numbers in message, and it is the IP address that SR UE distributes that described IP address is set to P-GW.

813, MSC receives that far-end session completes message, and far-end session completes message and carries the IP address that P-GW is SRUE distribution;

814, MSC sends call setup response message to SR UE, connects wireless side media resource and is connected with tunnel.MSC receives the VoP of described UE, is converted to IP packet, and distant end media IP address and port that destination address is set to carry in session response message, connect by tunnel, through P-GW, sends to remote equipment; First the ip voice media of remote equipment route to P-GW according to the IP address of described UE, P-GW finds tunnel to connect according to described UE IP address, IP packet is connected and sent to described MSC by tunnel, be transmitted to described UE after being converted to VoP by described MSC;

815, the media relevant information that MSC notice SR UE and far-end are consulted, as the coding/decoding information adopting, if UE does not support the encoding and decoding of current employing, MSC will consult encoding and decoding again with far-end;

If the media encoding and decoding that 816 MSC and far-end are consulted are general encoding and decoding that a terminal is all supported, the signaling control connection that MSC can set up by 810 steps, the media relevant information of MSC and far-end negotiation is passed to PCRF, by PCRF when user switches, when objective network is set up new bearer, pass to SR UE.

817, follow-up, SR UE is switched to objective network, and handling process during switching is referring to the switching flow shown in Figure 10 or Figure 11;

818, SR UE is switched to objective network, if not in IMS network registry mistake, need to initiate IMS and re-register flow process, this flow process is normal process;

After 819-820, SR UE have registered, to IMS network, send session invitation message, carry Session Hand-off sign (Session Transfer Indentification, STI) in message, media address remains unchanged, and signaling paths is switched to objective network.This step is standard I MS normal process, is not described in detail here.

Fig. 9 is the invention process four, the difference of the present embodiment and embodiment mono-is that SR UE user receives the flow process called time, MSC receives from P-GW the session invitation message that far-end sends, to far-end, return to session and complete message, the media address in message extends this as the SR UE IP address that P-GW distributes;

901, SR UE initiates access procedure at GERAN/UTRAN network, MSC also obtains user contracting data from HSS, in data, may comprise rSRVCC CAMEL-Subscription-Information and rSRVCC PDNContext, the described contextual information PDN Context of Packet Data Network comprises: target P-GW sign/address or APN indication, APN (Access Point Name, APN), wherein, APN indication is used to indicate and whether allows MSC is that APN selects P-GW, or whether APN distributes P-GW at home network;

902, MSC judgement user is rSRVCC user, MSC replaces UE to initiate IMS register flow path, this flow process is 3GPP normal process, be not described in detail herein, MSC judgement user can judge by the subscription data obtaining according to 901 steps for rSRVCC user, or can judge according to number section of user identity number;

903, MSC receives far-end session invitation message, carries remote subscriber face IP address and port numbers in message;

904, MSC is according to PDN Context select target P-GW, if comprise the address of P-GW in PDN Context, MSC select in PDN Context P-GW, if do not comprise P-GW address in P-GW Context, MSC indicates and selects according to APN, wherein: if APN indication allows MSC to select, MSC runs strategy according to the static configuration of oneself or utilization business, selects a local P-GW; If indication home network has configured P-GW, MSC obtains and distributes P-GW address to user attaching net;

If 905 network design PCRF, MSC may need the signaling control connection between foundation and PCRF, and this step is optional step;

906, MSC sends tunnel to target S/P-GW and sets up request, tunnel is set up and in request message, is carried rSRVCC APN, P-GW address, SR UE identify label, also comprise some other downlink tunnel security information, if tunnel adopts GTP tunnel mode, in message, also need to carry MSC for transmitting GTP tunnel IP address and port numbers;

If 907 network design PCRF, P-GW initiates IP and connects session establishment program, and P-GW is provided for identifying session and associated 905 step signaling control connections to PCRF, and this step is optional step.

908, P-GW judges that tunnel sets up the IP address of whether carrying UE in request message, if do not had, P-GW is SR UE distributing IP address; P-GW distributes tunnel IP resource;

909, P-GW sends and upgrades P-GW request message to the HSS under SR UE, and the address information of carrying P-GW in message, if the switching mode of being initiated by network shown in network support Figure 11 does not need this step;

910, S/P-GW returns and sets up tunnel acknowledgment message to MSC, in message, carrying P-GW is IP address and the S/P-GW side tunnel IP resource that SRUE distributes, if adopt GTP tunnel mode, P-GW may create default bearer tunnel and dedicated voice bearing tunnel, and the IP address of MSC binding SR UE is connected with tunnel;

911-913, MSC paging SR UE, to SR UE, send call setup request message, distribute called subscriber's wireless side media resource, when receiving called subscriber's call answering message, to far-end, send session invitation and complete message, in message, carry local terminal media IP address and port numbers, it is the IP that UE distributes that IP is set to P-GW, and MSC connects wireless side media resource and is connected with tunnel.MSC receives the VoP of SR UE, is converted to IP packet, and destination address is set to the distant end media IP address and the port that in 903 step session invitation message, carry, by tunnel, connects, and through P-GW, sends to far-end; First far-end IP voice medium is routed to P-GW according to the IP address of SR UE, and the tunnel that P-GW finds according to SR UE IP connects, and VoP is connected and sent to MSC by tunnel, by MSC, is transmitted to SRUE;

914, the media relevant information that MSC notice SR UE and far-end are consulted, the coding/decoding information for example adopting, if UE does not support the encoding and decoding of current employing, MSC will consult encoding and decoding again with far-end;

If the media encoding and decoding that 915 MSC and far-end are consulted are general encoding and decoding that a terminal is all supported, the signaling control connection that MSC can set up by 905 steps, the media relevant information of MSC and far-end negotiation is passed to PCRF, by PCRF when user switches, when objective network is set up new bearer, pass to SR UE.

916, follow-up, SR UE is switched to objective network, and handling process during switching is referring to the switching flow shown in Figure 10 or Figure 11;

917, SR UE is switched to objective network, if not in IMS network registry mistake, need to initiate IMS and re-register flow process, this flow process is normal process;

After 918-919, SR UE have registered, to IMS network, send session invitation message, carry Session Hand-off sign (Session Transfer Indentification, STI) in message, media address remains unchanged, and signaling paths is switched to objective network.This step is standard I MS normal process, is not described in detail here.

Figure 10 and Figure 11 are that UE is switched to E-UTRAN network signal flow process figure.

What Figure 10 described is to be chosen by SR UE, initiate CS territory to the handoff procedure in PS territory, SR UE is switched to E-UTRAN network, to network, initiate to adhere to or TAU process, in message, carry and switch indication (HandOver Indicator), at objective network, set up the bearer connection new with P-GW, P-GW arrives newly-built bearer connection the tunnel handoff of source network;

1001, SR UE determines to carry out wireless access gravity treatment, selects E-UTRAN network;

1002, SR UE sends adhere to/TAU request message to the MME of E-UTRAN network, carries and switch indication HO Indicator in message, and indication network triggers rSRVCC and switches;

1003, MME obtains user contracting data to the HSS under SR UE user, and this user contracting data comprises PDN Context and current network is the P-GW address that SR UE distributes;

1004, MME sends and creates bearing request message to target S/P-GW, carries User Identity, HO Indicator, and PDN Context information in message;

If disposed PCRF in 1005 networks, whether P-GW allows to create required carrying to PCRF inquiry;

1006, S/P-GW distributes carrying IP network resource, to MME, return and create carrying response message, create IP address and the port numbers of in carrying response message, carrying created carrying IP network resource, and the IP address of distributing for SR UE before, if preserve session TFT and the encoding and decoding relevant information of active session in P-GW or PCRF, be also contained in and in message, bring MME;

1007, MME notice EUTRAN distributes interface-free resources, and session TFT and the encoding and decoding relevant information of in P-GW or PCRF, preserving active session are passed to SR UE;

1008, after interface-free resources is assigned, MME returns to renewal bearing request message to S/P-GW, in message, carry IP address and port numbers that EUTRAN distributes for user's face, the tunnel that P-GW replaces source network newly-established bearer connection connects, connection is connected with far-end, thereby connect SR UE, is connected with the media of remote equipment.

Figure 11 determines by network the embodiment switching, the wireless measurement report that source network GERAN/UTRAN reports according to SR UE, and switching flow is initiated in decision-making, and by source network notification target network reservation resource, resource is ready, and notice SR UE is switched to objective network.

Step 1101, source network GERAN/UTRAN, according to the wireless quality measurement report of UE, determine to be switched to target EUTRAN network;

1102, source network GERAN/UTRAN sends handover request message to MSC, carries target cell information and cell-of-origin information in message;

1103, MSC is according to the MME of target cell information select target network, to MME, send CSto PS handover request message, in message, carry User Identity, PDN Context information, described PDN contextual information comprises: IP address, APN and P-GW address information etc.

If the non-GTP mode of tunnel style that 1104 source networks are set up, MME obtains user contracting data to the HSS under user, and the data such as relevant default bearer (Quality of Service, QoS) quality requirement;

1105, MME sends to P-GW the carrying request that creates, and approach S-GW creates in bearing request message and carries and switch indication (HO Indicator), PDN Context information, the IP address of User Identity and UE;

If 1106 objective networks have been disposed PCRF, whether P-GW allows to create required carrying to PCRF inquiry;

1107, P-GW and S-GW receive described establishment carrying request, distribute required carrying IP resource, and the IP address of distributed IP resource and port numbers are carried to response message by establishment feed back to MME, if the media information before P-GW or PCRF preservation user are switched is as TFT, Codec information, P-GW passes to MME by this message relevant information;

1108, MME receives and creates carrying response message, to EUTRAN, send handover request message (HORequest), in message, carry the IP address of P-GW distribution and for being connected with EUTRAN, transmit media with port, conversation media information before switching, the media IP resource that notice EUTRAN distributes interface-free resources to be connected with P-GW with reserved EUTRAN, after E-UTRAN resource is ready, to MME, return to handover acknowledge message, in message, encapsulate interface-free resources access parameter and the front conversation media information of switching that EUTRAN distributes;

1109, MME returns to CS to PS handover acknowledge message to MSC, comprises packaging information in the handover acknowledge message of receiving E-UTRAN in message;

1110-1111, MSC return to handover acknowledge message (HO Ack) to GERAN/UTRAN, in message, comprise packaging information in the handover acknowledge message of receiving E-UTRAN, GERAN/UTRAN sends switching command to SRUE, notice SR UE is switched to objective network, carries packaging information in handover acknowledge message in message;

1112, the interface-free resources access parameter that SR UE distributes according to E-UTRAN, is switched to the reserved Radio Resource of objective network;

1113, SR UE accesses successfully, to objective network E-UTRAN, sends handoff completion message, and E-UTRAN returns to handoff notification message to MME, and notice MME user has been switched;

1114, MME returns to renewal bearing request message to S/P-GW, in message, carry IP address and port numbers that EUTRAN distributes for user's face, the tunnel that P-GW replaces source network newly-established bearer connection connects, and connection is connected with far-end, thereby connect SR UE, is connected with the media of far-end;

1115-1116, MME be to MSC transmission handoff completion message, the bearer connection between MSC source of release network G ERAN/UTRAN interface-free resources and GERAN/UTRAN and MSC.

The foregoing is only embodiments of the invention, be not limited to the present invention, for a person skilled in the art, the present invention can have various modifications and variations.Within the spirit and principles in the present invention all, any modification of doing, be equal to replacement, improvement etc., within all should being included in claim scope of the present invention.

Claims

1. a method that strengthens single voice call service continuity, comprising:

At circuit commutative field, to the voice business continuity handoff procedure of packet-switched domain, at the circuit commutative field of objective network, set up the bearer connection between UE and packet switching network gateway P-GW; Described packet switching network gateway P-GW is connected with the bearer connection between packet switching network gateway P-GW described UE with remote equipment, at objective network, be that UE and described remote equipment are set up circuit commutative field to the session communication of packet-switched domain;

2. the method for claim 1, is characterized in that,

Described Packet Data Network contextual information also comprises: APN APN, and APN indication;

Described APN indication is used to indicate and whether allows described MSC is that described APN APN selects packet data network gateway P-GW, or is used to indicate described APN APN and whether at home network, has distributed P-GW.

3. the method for claim 1, is characterized in that,

4. the method for claim 1, is characterized in that,

5. the method for claim 1, is characterized in that, described foundation strengthens the step that the eMSC of mobile switching centre is connected with tunnel between packet data network gateway P-GW and is specifically divided into again:

6. method as claimed in claim 5, it is characterized in that, if connecting, described tunnel adopts general packet radio service gprs tunnel protocol (GTP tunnel mode), IP and port numbers that the described enhancing eMSC of mobile switching centre distributes default bearing and dedicated bearer, described eMSC sends tunnel to P-GW and sets up request message, tunnel is set up and in request message, is carried described user ID, APN APN, the default bearing of described eMSC side and the IP of dedicated bearer and port numbers, and selected object P-GW address information.

7. the method as described in claim 5 or 6, is characterized in that,

8. the method for claim 1, is characterized in that,

9. the method for claim 1, is characterized in that,

10. method as claimed in claim 8 or 9, it is characterized in that, described eMSC is that UE and described remote equipment are while setting up session communication, also consult media information with remote equipment, by described media information notice local terminal user equipment (UE), described media information comprises coding/decoding information and voice medium source and destination IP address and port.

11. the method for claim 1, is characterized in that,

Described user equipment (UE) is switched to objective network from source network, refers to by user equipment (UE) and changes and initiate to be switched to objective network from source network according to wireless quality;

Described UE adheres to or tracking area update request message to the mobile management entity MME transmission of described objective network, carries and switch indication in message;

Described MME carries out alternately according to the user contracting data and the described P-GW that obtain from user attaching network HSS, set up described UE in objective network and the bearer connection between P-GW, P-GW connects session to be switched to the bearer connection between described UE and P-GW by tunnel.

12. the method for claim 1, is characterized in that,

Described user equipment (UE) is switched to objective network from source network, refers to by source network and changes and initiate to be switched to objective network from source network according to the wireless quality of user equipment (UE);

Described source network sends handover request to the mobile management entity MME of described objective network;

13. methods as described in claim 11 or 12, is characterized in that,

Described user contracting data comprises described P-GW address and APN, APN indication information;

Described MME sends and sets up carrying request to described P-GW by way of gateway S-GW, sets up in bearing request message and carries and switch indication, user ID, APN and P-GW address;

Described P-GW receives carrying foundation request, and according to switching indication and described user ID, associated described tunnel connects, and is dispensed to the IP bearing resource of described objective network;

Described P-GW returns to carrying and sets up response message to MME, and bearing resource IP address and the port information that carries described P-GW distribution in response message set up in carrying;

Described MME notifies described objective network to set up the bearer connection between described UE and P-GW.

14. methods as claimed in claim 13, it is characterized in that, described method is also included in after carrying foundation, described P-GW receives more new bearer request of MME, according to described user ID, indicate associated described tunnel to be connected with switching, described P-GW connects the bearer connection between remote equipment and the described UE having set up and P-GW.

15. methods as claimed in claim 11, is characterized in that, described method is further included in before switching, and described P-GW upgrades current P-GW address to the HSS under described user.

16. as claim 1-6, and the method in 8,9,11,12,15 described in any one, is characterized in that,

17. as claim 1-6, and the method in 8,9,11,12,15 described in any one, is characterized in that,

18. 1 kinds of communication systems that strengthen single voice call service continuity, comprise: as the GERAN/UTRAN network of source network, E-UTRAN network as objective network, user equipment (UE) switches to objective network from source network, it is characterized in that: described system also comprises the enhancing eMSC of mobile switching centre, packet switching network gateway P-GW, user attaching network HSS, mobile management entity MME, is connected with S2a interface between described eMSC and P-GW;

Described P-GW is connected with the bearer connection between packet switching network gateway P-GW described UE with remote equipment, at objective network, be that UE and described remote equipment are set up circuit commutative field to the session communication of packet-switched domain;

19. communication systems as claimed in claim 18, is characterized in that, the S2a interface between described eMSC and P-GW is supported GPRS Tunnel Protocol GTP and/or proxy mobile IP protocol PMIP.

20. communication systems as claimed in claim 18, is characterized in that, described eMSC can be according to selecting P-GW in the grouped data network PDN contextual information the user contracting data obtaining from user attaching network HSS.

21. communication systems as claimed in claim 18, is characterized in that, described eMSC is after receiving the session invitation message of the session establishment request of UE local terminal or remote equipment, and eMSC sends to far-end the IP address that P-GW is user assignment.

22. communication systems as claimed in claim 18, it is characterized in that, described communication system further comprises the Source MSC of source mobile switching centre, described eMSC receives after the handover preparation request message of Source MSC transmission, according to Target cell in handover preparation request message, forward handover request message to target MME, notification target network allocation resource; Or directly return to response message, indication UE is linked into objective network, utilize UE and the bearer connection between P-GW at objective network, set up to realize switching.

23. communication systems as claimed in claim 22, is characterized in that, mobile management entity MME is received the handover request message of eMSC, create default bearer or MME and to eMSC, initiate single access speech business user registration after UE TAU completes.