WO2012149866A1

WO2012149866A1 - Method and system for single radio voice call continuity domain handover

Info

Publication number: WO2012149866A1
Application number: PCT/CN2012/074315
Authority: WO
Inventors: 高扬; 周蓝粢
Original assignee: 中兴通讯股份有限公司
Priority date: 2011-05-04
Filing date: 2012-04-18
Publication date: 2012-11-08
Also published as: CN102769880B; CN102769880A

Abstract

Disclosed is a method for single radio voice call continuity domain handover, using an application server (AS) to implement the function of an ATCF and using a multimedia resource function processor (MRFP) to implement the function of an ATGW. The method further comprises: after receiving a domain handover request from a single radio voice call continuity (SRVCC) user equipment (UE) that has been anchored to the AS and the MRFP, the AS performing media resource negotiation between the UE and a peer-end UE, so as to implement domain handover. Also disclosed is a system for single radio voice call continuity domain handover for implementing the method. The present invention definitely causes few changes to current protocols, so as to protect the investment in the existing network system and facilitate maintenance of the network system, thereby saving the cost of implementing enhanced SRVCC domain handover.

Description

TECHNICAL FIELD The present invention relates to a domain-based handover technology, and in particular, to a single wireless voice call continuity (SRVCC, Single Radio Voice Call Continuity) domain handover method and system . Background technique

The Internet Multimedia Subsystem (IMS) is the future development direction of multimedia communication and the most important component of the next generation network. It is a subsystem supporting IP multimedia services proposed by the 3GPP (3GPP, Third Generation Partnership Project). Its distinctive feature is the use of the Session Initial Protocol (SIP) system. Communication is independent of access mode. And with a variety of multimedia service control functions and separation of bearer capabilities, call and session separation, separation of applications and services, separation of services and networks, and the convergence of mobile networks and Internet services.

Single Radio Voice Call Continuity (SRVCC) implements voice switching between the IMS and the Circuit Switching (CS) in the Single Radio environment. The SRVCC is mainly for the UE of the Single Radio, that is, the UE can only use the 2G/3G Radio and the Long Term Evolution (LTE) network of the Radio at the same time. The demand of the Single Radio is proposed by the terminal manufacturer. The purpose is to reuse the RF and related circuits of 2G/3G and LTE networks.

SRVCC has a unique nature because of Single Radio: The switching between Radio is very fast, but before the handover, the CS-related network side channel needs to be established, and the remote end is updated.

SRVCC switching, in the process design, need to first CS channel creation and remote update (Remote Update), then switch from the packet switched domain to the circuit switched domain (PS to CS Handover); In the case of roaming, Remote Update Time is second. Under high-speed mobility, the user's packet switching (PS, Packet Switching) domain-related Radio (such as LTE Radio) is rapidly attenuated. It may be that the PS-related Radio has completely attenuated before the PS to CS Handover command is sent, which will result in the inability to complete the handover.

In general, the second-level Remote Update will also cause a certain Media Clip, resulting in a poor user experience (if more than 200ms, the user will be aware).

3GPP proposes to enhance the concept of SRVCC to solve the above-mentioned scheme of reducing switching time, specifically:

The bow I enters the access side media anchor point, reducing the signaling time of the Remote Update signaling. The switch enters the new access side anchor point access transfer control function (ATCF, Access Transfer Control Function) and the access transfer gateway (ATGW, Access Transfer Gateway); the call is anchored to the ATCF, reducing the switching distance and reducing the switching time.

FIG. 1 is a schematic structural diagram of a related network element involved in 3GPP enhanced SRVCC domain handover. As shown in FIG. 1 , in the structure of a related network element involved in 3GPP enhanced SRVCC domain handover, an access-side anchor point new function network element ATCF is introduced. And ATGW; the following briefly introduces the basic call and domain switching path processing before I switch to the ATCF and ATGW.

The basic call processing process before domain switching is as follows:

The UE initiates or receives a call in the PS domain, and performs information interaction with a proxy call session control function (P-CSCF, Proxy-Call Session Control Function) through the Gm interface;

The P-CSCF exchanges information with the ATCF through the Mw/Mx interface, and the ATCF controls the ATGW; the UE media is linked to the ATCF and the ATGW;

The UE is anchored to the ATCF and the ATGW;

The ATCF exchanges information with the Serving-Call Session Control Function (S-CSCF) through the Mw/Mx interface;

The S-CSCF triggers the service continuous "1" application server (SCC AS, Service Centralization and Continuity Application) through the initial filter rule (IFC, Initial Filter Criteria). Server ) ₀

The domain switching process is as follows:

The UE reports the radio access signal to the Evolved Universal Terrestrial Radio Access Network (E-UTRAN), and the E-UTRAN determines the triggering of the SRVCC handover to the CS domain; the mobile switching center (MSC, Mobile) The Switching Center carries a session transfer number (STN-SR, Session Transfer Number Single-Radio) to initiate a session switching operation;

The MSC initiates an initial INVITE session switching request to the ATCF, and carries a Request-URI as a STN-SR, a Session Description Protocol (SDP) supported by a Media Gateway (MGW, Media Gateway);

The ATCF associates the local end with the remote end to perform media resource negotiation and completes the domain handover process. After the domain handover succeeds, the P-CSCF releases the original UE's call in the PS domain.

Enhancing SRVCC technology has the following problems:

A new ATCF/ATGW network element needs to be introduced, and if the call is to be handed over, it needs to be anchored at the ATGW, and has a capacity requirement for the ATGW. At the same time, a new protocol interface between the P-CSCF and the ATCF needs to be introduced, and the existing network is changed. Larger. Summary of the invention

In view of the above, the main purpose of the present invention is to provide a method and system for switching a single wireless voice call continuity domain, which can enhance SRVCC domain switching by performing function expansion on existing network elements, since it is not necessary to The corresponding interface is changed, so the changes to the existing protocol are small, and the existing network investment is protected.

In order to achieve the above object, the technical solution of the present invention is achieved as follows:

A method for switching a single wireless voice call continuity domain, the function of the ATCF is implemented by the AS, and the function of the ATGW is implemented by the MRFP; the method further includes:

After the UE is anchored to the AS and the MRFP to implement the SRVCC service, the UE sends the domain cut to the AS. Change request

The AS performs media resource negotiation of the UE and its peer UE, and completes domain switching. Preferably, the method further includes:

The AS allocates an SRVCC handover number to the UE during UE registration of the SRVCC.

Preferably, the AS forwards the media resource update request to the peer UE by using the proxy call session control function P-CSCF when performing the media resource negotiation of the UE and the peer UE;

Or, the AS directly sends an update request for the media resource of the peer UE when performing media resource negotiation between the UE and the peer UE.

Preferably, after the domain switching is completed, the method further includes:

When the AS forwards the media resource update request to the peer UE through the P-CSCF, the P-CSCF releases the call of the UE in the packet switched PS domain;

When the AS directly sends an update request for the media resource of the opposite UE, the AS releases the call of the UE in the packet switched PS domain.

Preferably, the AS is connected to the called session control function CSCF through an IMS service control ISC interface; the AS controls the MRFP.

Preferably, the UE is anchored to the AS and the MRFP, and the media of the UE of the SRVCC is linked to the AS and the MRFP.

Preferably, the method further includes:

The domain handover request is initiated by a mobile switching center MSC in the circuit switched CS domain in which the UE is located.

Preferably, the method further includes:

Transmitting, by the UE, a radio access signal to an Evolved Universal Terrestrial Radio Access Network (E-UTRAN); the E-UTRAN determines to trigger an SRVCC handover according to the radio access signal of the UE. CS domain;

An initial INVITE session switching request is initiated by the MSC to the AS. The initial INVITE session switching request carries an SDP supported by a Request-URI and a media gateway, where the Request-URI is an STN-SR.

Preferably, the function of the ATCF is specifically implemented by the service continuity control application server SCC-AS of the visited domain.

A single wireless voice call continuity domain switching system, which implements the ATCF function by using the AS, and implements the ATGW function by using the MRFP;

The UE is configured to send a domain handover request to the AS after the SRVCC service is implemented on the AS and the MRFP;

The AS, after receiving the domain handover request of the UE, performs media resource negotiation of the UE and its opposite UE to implement domain handover.

Preferably, the AS is further configured to: when performing the media resource negotiation of the UE and the peer UE, or the AS is further configured to directly send the pair when performing media resource negotiation of the UE and the peer UE thereof An update request of the peer UE media resource.

Preferably, after the domain switching is completed,

When the AS directly sends an update request to the peer UE media resource, the AS releases the call of the UE in the PS domain.

Preferably, the domain handover request is initiated by an MSC of a circuit switched CS domain in which the UE is located.

Preferably, the UE is further configured to report a radio access signal to the E-UTRAN;

The E-UTRAN is further configured to determine that the SRVCC is triggered according to the radio access signal of the UE. Switch to the cs domain;

In the present invention, the function of the ATCF is implemented by using an application server (AS, Application Server) in the existing system, and the function of the ATGW is implemented by a Multimedia Resource Function Processor (MRFP); thus, since the AS and the MRFP are both For the existing network elements in the current system, it is not necessary to change the interfaces involved in the introduced network elements after the introduction of the ATCF and ATGW functions, and the current protocol changes must be small, so that not only the investment of the existing network system is performed. Protection, but also facilitates the maintenance of the network system, saving the cost of implementing SRVCC domain handover implementation. DRAWINGS

1 is a schematic structural diagram of related network elements involved in 3GPP enhanced SRVCC domain handover; FIG. 2 is a schematic structural diagram of related network elements involved in enhanced SRVCC domain handover according to an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of another related network element involved in enhancing SRVCC domain handover according to an embodiment of the present invention;

4 is a flow chart of Embodiment 1 of a method for switching a single wireless voice call continuity domain according to the present invention;

FIG. 5 is a flow chart of Embodiment 2 of a method for switching a single wireless voice call continuity domain according to the present invention. detailed description

The present invention will be further described in detail below with reference to the accompanying drawings. FIG. 2 is a schematic structural diagram of related network elements involved in enhancing SRVCC domain handover according to an embodiment of the present invention. As shown in FIG. 2, the present invention uses the network element AS and the MRFP in an existing network system as extension access control respectively. Function (ATCF, Access Transfer Control Function) and access transfer gateway (ATGW, Access Transfer Gateway) function to implement SRVCC domain switching. As shown in Figure 2, AT-AS (AS used as ATCF) and MRFP are deployed on the access side. Among them, there may be a Multimedia Resource Function Controller (MRFC) between the AT-AS and the MRFP. AT-AS is responsible for anchoring and switching, and controlling MRFP.

Based on the structure shown in Figure 2, the basic call process before domain switching is roughly as follows:

The UE initiates or receives a call in the PS domain, and performs information interaction with the P-CSCF through the Gm interface;

The P-CSCF exchanges information with the AT-AS through the ISC interface, and the AT-AS controls the MRFP; the UE media is linked to the AT-AS and the MRFP;

The UE is anchored to the AT-AS and the MRFP;

The AT-AS sends the related message to the P-CSCF through the ISC interface, or receives the related message sent by the P-CSCF through the ISC interface;

Subsequent call processing is the same as the IMS basic call, and the implementation details are not described here. The domain switching process is roughly as follows:

The UE reports the radio access signal to the E-UTRAN, and the E-UTRAN determines to trigger the SRVCC handover to the CS domain according to the radio access signal; the MSC carries the STN-SR to initiate a session switching operation;

The MSC initiates an initial INVITE session switching request to the AT-AS, and carries the Request-Uniform Resource Identifier (Request-URI) and the SDP supported by the MGW. The Request-URI is the STN-SR.

The AT-AS associates the local end with the remote end to negotiate media resources and complete the domain switching process.

After the domain handover succeeds, the P-CSCF releases the original UE's call in the PS domain. FIG. 3 is a schematic structural diagram of related network elements involved in enhancing SRVCC domain handover according to an embodiment of the present invention. As shown in FIG. 3, the present invention extends the functions of the network element AS and the MRFP in the existing network system as functions of the ATCF, respectively. The ATGW function is used to implement SRVCC domain switching. As shown in Figure 3, AT-AS (AS used as ATCF) and MRFP are deployed on the access side. Among them, MRFC can exist between AT-AS and MRFP. AT-AS is responsible for anchoring and switching, and controls. MRFP. Compared with the structure shown in FIG. 2, the structure shown in FIG. 3 differs from the structure shown in FIG. 2 only in the connection relationship between the AT-AS and the related network element. Specifically, the AT-AS is not like the FIG. As shown, the P-CSCF interacts with the PS domain and the home network, but directly with the PS domain and the home network.

The UE initiates or receives a call in the PS domain, and interacts with the P-CSCF through the Gm interface; the P-CSCF interacts with the AT-AS through the ISC interface, and the AT-AS controls the MRFP;

UE media is attached to AT-AS and MRFP;

The UE is anchored to the AT-AS and the MRFP;

The AT-AS sends the related message directly to the P-CSCF or the I/S-CSCF, or directly receives the related message through the P-CSCF or the I/S-CSCF;

The MSC initiates an initial INVITE session switch request to the AT-AS, and carries the Request-URL Request-Uniform Resource Identifier and the SDP supported by the MGW. The Request-URI is the STN-SR.

After the domain handover succeeds, the AT-AS releases the original UE's call in the PS domain.

In the present invention, the AT-AS allocates SRVCC to the UE during the UE registration process of the SRVCC. The handover number; the UE of the SRVCC uses the SRVCC handover number as an identifier when the domain is switched. The function of the ATCF is specifically implemented by the SCC-AS of the visited domain, that is, the AT-AS described above is specifically implemented by the SCC-AS. In the embodiments described below, this is no longer specifically emphasized.

4 is a flow chart of Embodiment 1 of a method for switching a single wireless voice call continuity domain according to the present invention. As shown in FIG. 4, the method for switching a single wireless voice call continuity domain of the present invention specifically includes the following steps:

Step 401: The SRVCC user UE-A carries the SDP in the PS domain to initiate a call to the UE-B, and the UE-A has been anchored to the AT-AS; the primary and the called user establish a call and enter a steady state;

The UE A reports the radio access signal to the E-UTRAN, and the E-UTRAN decides to trigger the SRVCC handover to the CS domain according to the radio access signal (for example, the current PS domain radio signal is poor, and is not suitable for communication); the MSC carries the STN-SR Initiating a session switching operation;

Step 402: The MSC initiates an initial INVITE session switching request to the AT-AS&&MRFP, and carries the Request-URI and the SDP supported by the MGW, where the Request-URI is the STN-SR. Step 403, the AT-AS&&MRFP connects the local UE and the remote end. The UE performs association and prepares to perform an update operation on the remote UE.

Step 404, AT-AS&&MRFP sends a REINVITE message to update the remote UE; Step 405, the P-CSCF forwards the REINVITE message to the home domain IMS;

Step 406, the home domain IMS sends an update media resource message to the terminal UE-B;

Step 407, UE B replies with 200 OK, and carries the terminal media capability of UE-B; Step 408, the home domain IMS forwards the response message to the visited domain P-CSCF;

Step 409, the visited domain P-CSCF forwards 200 OK to the AT-AS&&MRFP;

Step 410, AT-AS&&MRFP forwards to the MSC;

Step 411, the MSC replies with an ACK;

Step 412, AT-AS&&MRFP forwards the ACK to the P-CSCF;

Step 413: The P-CSCF forwards the ACK message to the home domain IMS. Step 414, the home domain IMS forwards the ACK message to the terminal UE-B;

At this point, the domain handover is completed, and AT-AS&&MRFP releases the UE-A call in the PS domain. FIG. 5 is a flowchart of Embodiment 2 of a method for switching a single wireless voice call continuity domain according to the present invention. As shown in FIG. 5, the method for switching a single wireless voice call continuity domain of the present invention specifically includes the following steps:

Step 501: The SRVCC user UE-A carries the SDP in the PS domain to initiate a call to the UE-B, and the UE-A has been anchored to the AT-AS; the calling and called user establishes a call and enters a steady state;

The UE A reports the radio access signal to the E-UTRAN, and the E-UTRAN decides to trigger the SRVCC handover to the CS domain according to the radio access signal; the MSC carries the STN-SR to initiate a session handover operation; Step 502, the MSC initiates an initial INVITE session handover request to the AT. - AS&&MRFP, and carrying the Request-URI and the SDP supported by the MGW, wherein the Request-URI is the STN-SR; Step 503, the AT-AS&&MRFP associates the local UE with the remote UE, and prepares to perform an update operation on the remote UE;

Step 504, AT-AS&&MRFP sends a REINVITE message to update the remote UE; AT-AS&&MRFP directly sends an update message to the home domain;

Step 505, the home domain IMS sends an update media resource message to the terminal UE-B;

Step 506, UE-B replies with 200 OK, and carries the media capability of the terminal UE-B; Step 507, the home domain IMS forwards the response message to the AT-AS&&MRFP;

Step 508, AT-AS&&MRFP forwards to the MSC;

Step 509, the MSC replies with an ACK;

Step 510, AT-AS&&MRFP forwards the ACK home domain IMS;

Step 511, the home domain IMS forwards the ACK message to the terminal UE-B;

At this point, the domain handover is completed, and AT-AS&&MRFP releases the call of UE A in the PS domain. The invention also discloses a switching system of a single wireless voice call continuity domain, which implements the function of the ATCF by using the AS, and implements the function of the ATGW by using the MRFP; The AS is configured to perform media resource negotiation of the UE and its peer UE after receiving a domain handover request of the UE that has been anchored to the AS and the SRVCC on the MRFP, and implement domain switching.

The specific structure of the switching system of the single wireless voice call continuity domain of the present invention can be understood by referring to the structures shown in Figs. 2 and 3 above. In the network hardware in the existing network system, the present invention has not been modified, but the functions of the relevant network elements therein have been expanded.

The AS is further configured to: when the media resource negotiation of the UE and the peer UE is performed, or the AS is further used to directly send the mediation when performing media resource negotiation between the UE and the peer UE thereof. The update request of the peer UE media resource.

Where, after completing the domain switch,

When the AS directly sends an update request to the peer UE media resource, the AS releases the call of the UE in the packet switched PS domain.

The domain handover request is initiated by a mobile switching center MSC of the circuit switched CS domain in which the UE is located.

Specifically, the UE is further configured to: report the radio access signal to the E-UTRAN;

The E-UTRAN is further configured to: according to the radio access signal of the UE, determine to trigger the SRVCC to switch to the CS domain;

An initial INVITE session switching request is initiated by the MSC to the AS. The initial INVITE session switching request carries a Request-URI and a session description protocol SDP supported by the media gateway, where the Request-URI is an STN-SR.

The above is only the preferred embodiment of the present invention and is not intended to limit the scope of the present invention.

Industrial applicability The function of the ATCF is implemented by using the AS in the existing system, and the function of the ATGW is implemented by using the MRFP. In this way, since the AS and the MRFP are the existing network elements in the current system, the introduced network elements are not required to be introduced after the ATCF and the ATGW function are introduced. The interface involved is changed, and the current protocol changes are inevitably smaller. This not only protects the investment of the existing network system, but also facilitates the maintenance of the network system and saves the cost of implementing the SRVCC domain handover implementation.

Claims

Claim

A method for switching a single wireless voice call continuity domain, wherein the method includes: after the user equipment UE is anchored to the application server AS and the multimedia resource function processor MRFP to implement a single wireless voice call continuity SRVCC service, Sending a domain handover request to the AS; the AS performs media resource negotiation of the UE and its peer UE, and completes domain handover.

2. The method according to claim 1, wherein the method further comprises:

3. The method according to claim 1, wherein the AS forwards the media to the peer UE by using a proxy call session control function P-CSCF when performing media resource negotiation of the UE and its peer UE Resource update request;

The method according to claim 3, wherein after the domain switching is completed, the method further includes:

The method according to claim 1, wherein the AS is connected to the called session control function CSCF through an IMS service control ISC interface; the AS controls the MRFP.

The method according to claim 1, wherein the UE is anchored to the AS and the MRFP, and the media of the UE of the SRVCC is linked to the AS and the MRFP.

The method according to claim 1, wherein the method further comprises: The domain handover request is initiated by a mobile switching center MSC of the circuit switched CS domain in which the UE is located.

8. The method according to claim 7, wherein the method further comprises:

Transmitting, by the UE, a radio access signal to an Evolved Universal Terrestrial Radio Access Network (E-UTRAN); the E-UTRAN determines to trigger a handover of the SRVCC to the CS domain according to the radio access signal of the UE;

The method according to any one of claims 1 to 8, wherein the function of the ATCF is specifically implemented by a service continuity control application server SCC_AS of a visited domain.

10. A switching system for a single wireless voice call continuity domain, wherein the function of the ATCF is implemented by the AS, and the function of the ATGW is implemented by the MRFP;

The system according to claim 10, wherein the AS is further configured to: when performing media resource negotiation of the UE and the peer UE, forwarding, by the P-CSCF, a media resource update request for the peer UE ;

Or, the AS is further configured to directly send an update request for the media resource of the opposite UE when performing media resource negotiation between the UE and the peer UE.

12. The system according to claim 11, wherein after the domain switching is completed,

When the AS forwards the media resource update request to the peer UE through the P-CSCF,

The P-CSCF releases the call of the UE in the packet switched PS domain; When the AS directly sends an update request to the peer UE media resource, the AS releases the UE's call in the PS domain.

13. The system of claim 10, wherein the domain handover request is initiated by an MSC of a circuit switched CS domain in which the UE is located.

14. The system of claim 13 wherein

The UE is further configured to: report the radio access signal to the E-UTRAN;