CN102131232B

CN102131232B - Method and system for realizing service GPRS (General Packet Radio Service) supporting node and single-mode business continuity

Info

Publication number: CN102131232B
Application number: CN201010000680.9A
Authority: CN
Inventors: 谢振华; 陶全军
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2010-01-15
Filing date: 2010-01-15
Publication date: 2015-01-28
Anticipated expiration: 2030-01-15
Also published as: CN102131232A

Abstract

The invention discloses a method and system for realizing a service GPRS (General Packet Radio Service) supporting node and single-mode business continuity. The method comprises the following steps of: when a handover request sent by an access network is received, initiating a first switching process to an SGSN (Service GPRS Supporting Node) by a control network element as a speech load, and obtaining first media information by the first switching process; initiating a second switching process to an MSC (Mobile Switching Centre) by the control network element; sending a transferred number to the MSC by the second switching process and obtaining second media information; initiating an IMS (Information Management System) conversation transferring process by the MSC by taking the transferred number as a target, and performing a CS (Circuit Switch) switching process; sending the second media information to the SGCN via the first switching process by the control network element; sending the first media information to the MSC through the second switching process; obtaining conversion media connection information by the SGSN; and setting the connection information of the media data according to the conversion media connection information, wherein the media data is packaged in the load built by the first switching process.

Description

Service GPRS support node, method and system for realizing single-mode service continuity

Technical Field

The invention relates to the field of communication, in particular to a service GPRS support node, a method and a system for realizing single-mode service continuity.

Background

An IP Multimedia Subsystem (IMS) is an IP-based Network architecture proposed by the third Generation partnership project (3rd Generation partnership project, 3GPP), which constructs an open and flexible service environment, supports Multimedia applications, and can provide rich Multimedia services for users.

In the IMS service system, the control layer and the service layer are separated, the control layer does not provide specific services, and only provides necessary functions of triggering, routing, charging and the like for the service layer. The service triggering and control functions in the control layer are completed by a Call Session Control Function (CSCF), which is divided into three types of Proxy (Proxy), query (inquiring) and service (Serving), wherein the Serving is mainly responsible, and the inquiring type is optional); the service layer is composed of a series of application servers (AS for short), and can provide specific service services, and the AS may be an independent entity or may be located in the S-CSCF. And the control layer (S-CSCF) controls service triggering according to the subscription information of the user, calls the service on the AS and realizes the service function. User Equipment (UE) is responsible for interacting with users, and some UEs have multiple network access modes, including: access to the network over a Packet Switch (PS) domain (LTE or HSPA) of 3GPP, access to the network over a Circuit Switch domain (CS) domain, etc. If the CS network is configured with an enhanced Mobile Switching Center (MSC), and the enhanced MSC provides an interface of the SIP protocol to interact with the IMS network, signaling interaction between the IMS network and the CS network may be implemented by the enhanced MSC, and Media interaction may be implemented by a Media Gateway (MGW) controlled by the enhanced MSC.

For a UE with multiple access modes, if the UE can only access the network in one access mode at a certain time, the UE is called a single-mode UE. If it is performing a call service in a PS access mode (LTE network or HSPA network), when the UE moves elsewhere and needs to change to a CS access mode, the UE and the network can provide a way to keep the call service being performed by the UE from being interrupted, which is called single-mode service continuity.

Fig. 1 is a schematic diagram of a conventional single-mode service continuity, which illustrates a signaling path and a media path of a session between a UE and a remote UE, and a signaling path and a media path of a session between a UE and a remote UE after single-mode service continuity occurs.

Wherein 101 is a signaling path between the UE and the PS access Network (i.e. enhanced Node B (eNB) of the LTE Network, or Radio Network Controller (RNC) of the HSPA Network), and communicates with each other through an air interface signaling protocol of the LTE Network or the HSPA Network; 102 is a signaling path between the PS access network and a control network element (i.e., a Mobility Management Entity (MME) of the LTE network, or a Serving GPRS Support Node (SGSN) of the HSPA network); 103 is a signaling path between the PS network control network element and a Packet data Gateway (i.e., a Serving Gateway (SGW) and a Packet data network Gateway (PGW) of the LTE network, or a Global GPRS Support Node (GGSN) of the HSPA network) of the PS network; 104 is a switching signaling interface between the PS network control network element and the MSC, through which the PS network can inform the MSC to prepare CS network resources and PS bearer resources for the UE; 105 is a signaling path between the UE and the CS access network, or between the UE and the CS access network and the core network, and communicates with each other through an air interface signaling protocol of the CS network; 106 is a signaling path between the CS access network or the CS core network and the enhanced MSC; 107 is a part of an IMS signaling path between the UE and the CSCF, and the part of the signaling path is transmitted through a PS network; 108 is a part of IMS signaling path between MSC and CSCF, the end point of the part of signaling path is the packet data gateway of PS network, MSC and UE make the IMS network not change the near-end access path by sharing the signaling path; 109 is another part of an IMS signaling path between the UE or the MSC and the CSCF, where the signaling path is transferred through an IP network, and signaling data sent on the signaling path is forwarded by the CSCF to the SCC AS to implement the SCC AS controlling session signaling between the UE and the remote UE, and 109 is a near-end Access (Access leg) path for the SCC AS; 110 is a signaling path between the SCC AS/CSCF and the Remote UE, which communicates with each other through the SIP protocol of IMS, and 110 is a Remote leg (Remote leg) path for the SCC AS.

Before the switching occurs, the UE establishes a bearer with the remote UE through the PS network, wherein one part of the bearer is the bearer in the PS network, and the other part of the bearer is the connection in the IP network; after switching, the media connection between the UE and the remote UE consists of three parts, one is CS media connection, and the other is the bearer between the MSC and the packet data gateway of the PS network, and is connected to the connection in the IP network to which the original media is connected. The media connections before and after switching are shared by the same connection, so that the media connection updating operation does not need to be carried out on the remote UE in the switching process.

In the following, the MSC and the MGW controlled by it are used as one entity to simplify the description, and standard interfaces and flow interactions are used between them.

Fig. 2 is a flowchart of a conventional single-mode service continuity implementation process, which describes that an IMS voice call is established between a UE and a remote UE, a media connection is formed by a PS connection between the UE and a PS access network, a PS connection between the PS access network and a packet data gateway of the PS network, and an IP connection between the packet data gateway of the PS network and the remote UE, and a process of a UE performing handover and a network implementing single-mode service continuity is described as follows:

step 201, the UE sends a Measurement report to the PS access network, for example, sends a Measurement report message, which includes signal strength information of the target network;

step 202, the PS access network determines to switch the UE call to the target network according to the signal strength, and sends a Handover request, for example, a Handover Required message, to a control network element of the PS network;

step 203, the control network element judges that the UE establishes a bearer for the voice call, decides to switch the voice call and the corresponding IMS signaling to the CS domain of the target network, and sends a Handover Request to the MSC, for example, sends a PS to CS Handover Request message, which carries IMS protocol state information of the UE and IMS call media resource information of the UE;

step 204, if the UE has other non-voice call services, the control network element will simultaneously send a handover Request to the PS domain of the target network, and handover these services to the PS domain of the target network, for example, send a Forward location Request message.

Step 205, the MSC sends a switching Request to the CS domain of the target network, if the target cell is controlled by the MSC, the MSC sends a Handover Request message, otherwise, the MSC sends a MAP _ Prepare _ Handover Request message to the MSC controlling the target cell;

step 206, the CS domain of the target network sends a Handover Response, for example, sends a Handover Response message carrying the prepared CS media resource information, or sends a MAP _ Prepare _ Handover Response message carrying a Handover number;

step 207, if the target cell is not controlled by the MSC, the MSC initiates a link establishment request according to the handover number in step 205, for example, sending an IAM (initial address message) or an INVITE (INVITE) message, where the target of the message is the handover number;

step 208, the MSC of the control target cell receives the link establishment request of step 207, associates the link establishment request with the handover request according to the handover number, and sends a link establishment response, such as sending an ACM (address completion message) or 183 Session Progress message;

step 209, and at the same time as the steps 204-207, the MSC prepares the bearer resource;

step 210, the MSC sends a Handover Response to a control network element of the PS network, for example, sends a PS to CS Handover Response message, where the message carries bearer resource information of the MSC;

step 211, if the control network element also sends a handover request to the PS domain of the target network, the PS domain of the target network sends a handover response, for example, sends a Forward relocation response message, which carries the bearer resource information of the target network;

step 212, the control network element associates step 210 with step 211, and sends a Handover Command to the PS access network, for example, sends a Handover Command message, which carries the obtained bearer resource information;

step 213, the PS access network sends a switching command to the UE, if the PS network is an LTE network, a Handover from LTE message is sent, and if the PS network is an HSPA network, a Handover from UTRAN message is sent;

step 214, the UE modulates to a target network, and the target network is informed;

step 215, if the target cell is not controlled by the MSC, the MSC controlling the target cell sends a link establishment response message, such as an ANM (answer message) or 200OK message, to the MSC;

step 216, the MSC receives the notification that the UE modulates to the target network or the link establishment response message sent by the MSC controlling the target cell, and sends a Handover completion message, such as a PS to CS Handover Complete message, to the control network element of the PS network;

step 217, if the control network element sends a handover request to the PS domain of the target network, the PS domain of the target network also sends a handover Complete message, such as a Forward Relocation Complete message, to the control network element;

step 218, the control network element immediately sends a completion acknowledgement message to the MSC, for example, sends a PS to CS Handover Complete ACK message;

step 219, if the control network element receives the message of step 217, immediately sending a completion acknowledgement message to the PS domain of the target network, for example, sending a Forward relocation complete ACK message;

step 220, the MSC sends an update message, for example, a Modify Bearer Request message, to the packet data gateway of the PS network, so as to update the PS Bearer information, including connection information between the control plane and the user plane;

step 221, if the control network element sends a completion confirmation message to the PS domain of the target network, the PS domain of the target network sends an update message, for example, a Modify Bearer Request message, to the packet data gateway of the PS network, so as to update the PS Bearer information, including the connection information between the control plane and the user plane. From this, the handover is completed.

As described above, in the existing single-mode service continuity implementation method, the MSC requires to establish a PS connection, and the MSC can only control the MGW to establish an IP connection, which requires that the MSC of the CS domain must provide the functions of the PS domain, but the implementation manners of the PS domain device and the CS domain device are different, thereby increasing the implementation complexity.

Disclosure of Invention

The present invention mainly aims to provide a method and a system for implementing SGSN, a control network element, and single-mode service continuity, so as to at least solve the above problems.

According to an aspect of the present invention, a method for implementing single-mode service continuity is provided, including: after receiving a switching request sent by an access network, a control network element initiates a first switching process to an SGSN for voice bearing and obtains first media information through the first switching process; the control network element initiates a second switching process to the MSC, sends the transfer number to the MSC through the second switching process, and obtains second media information; MSC initiates IMS session transfer process with transfer number as target and executes CS switch process; the control network element sends the second media information to the SGSN through the first switching process and sends the first media information to the MSC through the second switching process; the SGSN acquires the session media connection information and sets the connection information of the media data according to the session media connection information, wherein the media data is packaged in the bearer established by the first switching process.

According to another aspect of the present invention, there is provided a system for implementing single mode service continuity, including: a control network element, an SGSN and an MSC. The control network element is used for initiating a first switching process to the SGSN for voice loading after receiving a switching request sent by an access network, acquiring first media information through the first switching process, initiating a second switching process to the MSC, sending a transfer number to the MSC through the second switching process, acquiring second media information, sending the second media information to the SGSN through the first switching process, and sending the first media information to the MSC through the second switching process; the SGSN is used for negotiating media information through a first switching process in the first switching process and setting the connection information of media data according to the session media connection information acquired through the first switching process, wherein the media data is packaged in a bearer established in the first switching process; and the MSC is used for initiating an IMS session transfer process by taking the transfer number as a target in the second switching process, executing a CS switching process and negotiating the media information through the second switching process.

According to still another aspect of the present invention, there is provided an SGSN comprising: the system comprises a switching processing module, a connection mapping module and a data packaging module. A switching processing module, configured to establish a bearer between an SGSN and a data gateway for a first switching process initiated by a voice bearer through a control network element, negotiate media information and obtain session media connection information through the first switching process, and transmit the established bearer information, the media connection information indicated by the media information, and the session media connection information to a connection mapping module; the connection mapping module is used for storing the carried information and the media connection information in a correlation manner and storing the session media connection information; and the data packaging module is used for receiving the media data on the media connection, packaging the media data on the bearer according to the bearer information which is stored by the connection mapping module and is associated with the media connection, and setting the connection information of the media data packaged on the bearer according to the session media connection information stored by the connection mapping module.

According to yet another aspect of the present invention, there is provided a controlling network element, comprising: the device comprises a receiving module, a first switching processing module and a second switching processing module. The receiving module is used for receiving a switching request sent by an access network and triggering the first switching processing module and the second switching processing module when the switching request is received; the first switching processing module is used for initiating a first switching process to the SGSN for voice bearing, acquiring first media information through the first switching process and sending second media information to the SGSN; and the second switching processing module is used for initiating a second switching process to the MSC, sending the transfer number and the first media information to the MSC through the second switching process, and acquiring the second media information.

By the invention, the IP media data transmitted by the MGW controlled by the MSC is encapsulated to the load between the packet data gateway of the PS network and the load established by the SGSN, thereby realizing the continuity of the single-mode service, dividing the CS domain function and the PS domain function of the MSC, avoiding the problem of switching the IMS signaling load and solving the control plane updating problem of the packet data gateway of the PS network.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention. In the drawings:

fig. 1 is a schematic diagram of existing single-mode service continuity;

fig. 2 is a flow chart of a conventional single-mode service continuity implementation;

fig. 3A is a schematic structural diagram of a system for implementing single-mode service continuity according to an embodiment of the present invention;

fig. 3B is a single mode service continuity architecture diagram of an embodiment of the present invention;

fig. 4A is a schematic diagram of single-mode service continuity according to an embodiment of the present invention;

FIG. 4B is a functional diagram of an SGSN according to an embodiment of the invention;

fig. 5 is a flowchart of a method for implementing single-mode service continuity according to an embodiment of the present invention;

FIG. 6 is a flow chart of a first embodiment of the present invention;

FIG. 7 is a flowchart of a second embodiment of the present invention;

FIG. 8 is a flow chart of a third embodiment of the present invention;

FIG. 9 is a flow chart of a fourth embodiment of the present invention;

FIG. 10 is a flow chart of a fifth embodiment of the present invention;

FIG. 11 is a flow chart of a sixth embodiment of the present invention;

FIG. 12 is a flow chart of a seventh embodiment of the invention;

fig. 13 is a structural diagram of an SGSN according to an embodiment of the present invention;

fig. 14 is a schematic structural diagram of a first handover processing module of an SGSN according to an embodiment of the present invention;

fig. 15 is a schematic structural diagram of a controlling network element according to an embodiment of the present invention.

Detailed Description

The invention will be described in detail hereinafter with reference to the accompanying drawings in conjunction with embodiments. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.

First, a system for implementing single-mode service continuity according to an embodiment of the present invention is described below.

Fig. 3A is a schematic structural diagram of a system for implementing single-mode service continuity according to an embodiment of the present invention, and as shown in fig. 3A, the system includes: controlling network element 2, SGSN4 and MSC 6. Each of the above network elements is further described below.

A control network element 2, configured to initiate a first handover procedure to an SGSN4 for a voice bearer of a UE after receiving a handover request sent by an access network, initiate a second handover procedure to an MSC6, obtain first media information through the first handover procedure, send second media information to an SGSN4, send a transfer number and the first media information to an MSC6 through the second handover procedure, and obtain the second media information through the second handover procedure; the bearer between the SGSN4 and the data gateway may be established through a first handover procedure, which may be referred to as an inter-radio access technology network handover procedure in a particular application.

In a specific application, the first media information may include: the media connection information of the SGSN4, and the second media information may include: media connection information of Media Gateways (MGWs) controlled by the MSC 6.

SGSN4, configured to negotiate media information in the first handover procedure, and set connection information of media data according to session media connection information obtained through the first handover procedure, where the media data is encapsulated in a bearer established in the first handover procedure; through the first and second handover procedures, the MSC6 may establish a media connection between the SGSN4 and the MGW controlled by the MSC 6.

In a specific application, in the process of negotiating the media information between the SGSN4 and the MSC6, the media information sent by the SGSN4 to the MSC6 (sent by the controlling network element 2) includes: media connection information of SGSN 4; the media information sent by the MSC6 to the SGSN4 (sent by controlling network element 2) includes: media connection information of Media Gateways (MGWs) controlled by the MSC 6. Specifically, the SGSN4 sends the media information of the SGSN4 (i.e., the first media information) to the control network element 2 in the first handover procedure, the MSC6 sends the media information of the MGW controlled by the MSC6 (i.e., the second media information) to the control network element 2 in the second handover procedure, and the control network element 2 sends the first media information to the MSC6 through the second handover procedure and sends the second media information to the SGSN4 through the first handover procedure after receiving the first media information.

The MSC6 is configured to initiate an IMS session transfer procedure with the transfer number as a target in the second handover procedure, execute a CS handover procedure, and negotiate media information through the second handover procedure. In a specific application, the second handover procedure may also be referred to as a single mode handover procedure.

Further, if the UE currently has a non-voice bearer, the controlling network element 2 is further configured to initiate a third handover procedure for the non-voice bearer when initiating the first handover procedure.

In the embodiment of the present invention, the first handover procedure initiated by the controlling network element 2 to the SGSN4 includes, but is not limited to, the following procedures: the controlling network element 2 sends a handover request message (for convenience of distinction, referred to as a first handover request message in the embodiment of the present invention, and the handover request message may carry the second media information) to the SGSN 4; after receiving the first handover request message, the SGSN4 returns a handover response message (which may carry the first media information) to the control network element 2; after the UE is modulated to the target network, the SGSN4 sends a handover complete message (for convenience of distinction, the handover complete message is referred to as a first handover complete message in the embodiment of the present invention) to the controlling network element 2, and the controlling network element 2 returns a handover complete confirm message (for convenience of distinction, the handover complete confirm message is referred to as a first handover complete confirm message in the embodiment of the present invention, and the message may carry the second media information) to the SGSN4 after receiving the handover complete message.

And the second handover procedure initiated by controlling network element 2 to MSC6 includes, but is not limited to, the following procedures: the controlling network element 2 sends a handover request message (referred to as a second handover request message in the embodiment of the present invention) to the MSC 6; after receiving the handover request, the MSC6 returns a handover response message (the handover response message may carry the second media information) to the controlling network element 2; after the UE modulates to the target network, the MSC6 sends a handover complete message (for convenience of distinction, the handover complete message is referred to as a second handover complete message in the embodiment of the present invention), and the control network element 2 returns a handover complete confirmation message (referred to as a second handover complete confirmation message in the embodiment of the present invention, and the message may carry the first media information) to the MSC6 after receiving the handover complete message.

The third handover procedure is basically similar to the first handover procedure and the second handover procedure, except that the third handover procedure is initiated by the control network element to the target PS domain, and the detailed procedure is not repeated.

Further, in the first handover procedure, after the controlling network element 2 receives the first handover complete message (i.e. the handover complete message for the first handover procedure) and the message for releasing the voice bearer sent by the SGSN4, the controlling network element 2 is further configured to send a first handover complete confirm message to the SGSN4, and if the controlling network element 2 initiates the third handover procedure, the controlling network element 2 is further configured to send a third handover complete confirm message (i.e. the handover complete confirm message for the third handover procedure) for the non-voice bearer; and the SGSN4 releases the bearer resources after receiving the first handover complete confirm message. In a specific application, the SGSN4 may release the bearer resource immediately after receiving the first handover complete confirm message, or may release the bearer resource after receiving a predetermined time after receiving the first handover complete confirm message, or release the bearer resource when receiving the release bearer message, or the SGSN4 may send a bearer update request to the data gateway after receiving the first handover complete confirm message, and release the bearer resource after sending the predetermined time after sending the bearer update request.

In a specific application, the system for implementing the single-mode service continuity according to the embodiment of the present invention is completed based on the network architecture shown in fig. 3B, and since the CS domain handover operation is a standard process, the CS domain handover process is not described again for simplifying the description, and therefore, an access network entity of a target network is not shown in the following drawings.

The connection of the segments in fig. 3B is explained below.

301, a signaling interface between the UE and the PS access network (i.e. an enhanced NodeB (eNB) of the LTE network, or a Radio Network Controller (RNC) of the HSPA network) communicates with each other through an air interface signaling protocol of the LTE network or the HSPA network;

302, a signaling interface between the UE and a target network access network (i.e. a Radio Network Controller (RNC) of a 2G or 3G network, or a Base Station Subsystem (BSS), for short), communicating with each other through an air interface signaling protocol of the 2G or 3G network;

303, a signaling interface between the PS access network and a control network element (i.e. MME of LTE network or SGSN of HSPA network) to implement mobility management function;

304, controlling a signaling interface between the network element and a packet data gateway of the PS network (i.e. SGW and PGW of LTE network, or GGSN of HSPA network) to implement a bearer management function;

305, controlling a signaling interface between the network element and the SGSN by the PS network to realize a bearing switching function;

306, controlling a signaling interface between the network element and the MSC to realize the function of switching from PS to CS;

307, an interface between the target network access network and the MSC;

308, the signaling path between the MSC and the IMS network can be an IMS signaling interface, and can also be accessed to the IMS network through an access gateway of the IMS;

309, the packet data gateway of the PS network interfaces with the IMS network, providing IP connectivity.

In the following, for simplifying the description, the MSC and the MGW controlled by the MSC are described as an entity, and the MSC and the MGW interact with each other by using a standard interface and a flow.

Fig. 4A is a schematic diagram of single-mode service continuity implemented in the embodiment of the present invention, and describes a signaling path and a media path of a session between a UE and a remote UE, the media path of the session between the UE and the remote UE after a handover occurs, and the signaling path and the media path after an MSC performs an IMS transfer operation, where the IMS transfer operation takes a relatively long time, and the media path after the handover is only a transition path before the IMS transfer operation is completed.

The original IMS session signaling of the UE is connected to the IP network by the access service provided by the PS network and is connected to the IMS network by the IP network, and the original IMS voice call media path is connected to the IP network by the access service provided by the PS network; after the switching occurs, the voice call media of the UE is provided with CS access by a target network, the call control signaling is also realized by a CS signaling protocol, the CS media connection is converted into IP media connection by MGW controlled by MSC, and is connected to SGSN through IP network, the SGSN packages the media data on the IP media connection into a bearer to realize the exchange of media data with a packet data gateway of PS network, after the switching, the media connection shares the IP media connection part of the packet data gateway of the PS network, and the IP media connection and the bearer after the switching are transition media connection; when the switching operation is carried out, MSC also executes the transfer operation of IMS, after the transfer operation is completed, the new media connection replaces the transition media connection, and the single mode service continuity is completed.

Fig. 4B is a functional diagram of an SGSN4 according to an embodiment of the present invention, which illustrates that after handover, after IP media connection between an MGW and an SGSN controlled by an MSC is encapsulated by a bearer established by the SGSN, communication with a remote UE is achieved, and for the remote UE, a media connection address does not change:

the MGW controlled by MSC establishes IP media connection with SGSN so as to transfer IP media data, SGSN packages IP media data into the bearer between the MGW and the packet data gateway of PS network, and modifies the original connection address of IP media connection as UE, and the target connection address is remote UE, so that the packet data gateway of PS network can reuse the original IP media connection, and media data exchange between MGW controlled by MSC and remote UE can be realized without updating remote end.

The MSC and SGSN negotiate media information through the handover procedure on the 305 and 306 interfaces in fig. 3B to establish an IP media connection; the SGSN establishes a bearer between the SGSN and the data gateway through the handover procedure on the 305 interface in fig. 3B, and acquires session media connection information through the handover procedure on the 305 interface in fig. 3B, thereby acquiring a connection address of the UE and a connection address of the remote UE.

The following describes a method for implementing single mode service continuity according to an embodiment of the present invention, which can be implemented by the above system for implementing single mode service continuity.

Fig. 5 is a flowchart of a method for implementing single-mode service continuity according to an embodiment of the present invention, and as shown in fig. 5, the method mainly includes the following steps (step S502-step S510):

step S502, after receiving a switching request sent by an access network, a control network element initiates a first switching process to SGSN for voice bearing, and obtains first media information through the first switching process;

in the specific implementation process, if there is currently a non-voice bearer of the UE (i.e., the UE is currently performing a non-voice service), the control network element further initiates a third handover procedure for the non-voice bearer.

In a specific application, the first handover procedure initiated by the control network element may be referred to as an inter-radio access technology network handover procedure, and is not limited in this embodiment of the present invention.

Step S504, the control network element initiates a second switching process to the MSC, sends the transfer number to the MSC through the second switching process, and obtains second media information;

in a specific application, the second handover procedure initiated by the control network element may be referred to as a single-mode handover procedure, which is not specifically limited in the embodiment of the present invention.

Step S506, MSC initiates IMS conversation transfer process with transfer number as target, and executes CS switching process;

through IMS session transfer process and CS switch process, CS media and signaling path, MSC and signaling path between remote UE and MGW and remote UE after single-mode service continuity is completed can be established.

Step S508, the control network element sends the second media information to SGSN through the first switching process, send the first media information to MSC through the second switching process;

in a specific implementation process, the first media information sent by the SGSN to the MSC includes: media connection information of the SGSN;

the second media information sent by the MSC to the SGSN includes: MSC controlled MGW media connection information.

Through the first media information and the second media information, the media connection between the SGSN and the MGW controlled by the MSC can be established.

Step S510, the SGSN acquires session media connection information through the first handover procedure, and sets connection information of media data according to the session media connection information, wherein the media data is encapsulated in a bearer established through the first handover procedure.

In a specific application process, in the first handover process, after releasing an original session or deleting a voice in the original session, the control network element receives a message of releasing (or deleting) a voice bearer, so as to feed back a handover completion confirmation message, in an embodiment of the present invention, the processing of the handover completion confirmation message includes, but is not limited to, the following six methods:

method one, in which handover is completed later than IMS session transfer is completed. Specifically, the method can be realized by the following steps:

step 1, in a first switching process initiated by a control network element to an SGSN, after receiving a first switching completion message and a message for releasing (or deleting) a voice bearer sent by the SGSN, the control network element sends a first switching completion confirmation message to the SGSN, and if the control network element initiates the third switching process for a non-voice bearer, the control network element also sends a third switching completion confirmation message for the non-voice bearer (namely, sends a third switching completion confirmation message to a target PS domain) after receiving the message for deleting the voice bearer;

and step 2, after the SGSN receives the first switching completion confirmation message, releasing the bearing resources.

Method two, in this method, the handover complete acknowledgement is sent after a predetermined time. Specifically, the method can be realized by the following steps:

step 1, in a first switching process initiated by a control network element to an SGSN, the control network element receives a first switching completion message sent by the SGSN and sends a first switching completion confirmation message to the SGSN after waiting for a preset time;

In the method, after receiving the switching completion confirmation message sent by the control network element, the SGSN waits for the preset time and releases the resources. Specifically, the method can be realized by the following steps:

step 1, in a first switching process initiated by a control network element to an SGSN, after receiving a first switching completion message sent by the SGSN, the control network element immediately sends a first switching completion confirmation message to the SGSN according to a standard process;

and step 2, the SGSN releases the bearing resource after receiving the first switching completion confirmation message and waiting for the preset time.

And a fourth method, in the method, the control plane is updated to SGSN after voice switching, and the resources are released after the preset time. Specifically, the method can be realized by the following steps:

step 1, in a first switching process initiated by a control network element to an SGSN, if the control network element initiates the third switching process for a non-voice bearer, sending a first switching completion confirmation message to the SGSN and waiting for a specific time, and then sending a third switching completion confirmation message for the non-voice bearer;

and 2, after receiving the switching completion confirmation message, the SGSN starts timing, and when the preset time is up or the bearer release message is received, the SGSN releases the bearer resources.

In the method, a control plane is updated to a control network element after voice handover, and specifically, the method can be implemented by the following steps:

step 1, in a first switching process initiated by a control network element to an SGSN, if the control network element initiates the third switching process, sending a first switching completion confirmation message to the SGSN and waiting for a specific time, and then sending a non-voice-bearing third switching completion confirmation message;

step 2, after receiving the first switching completion confirmation message, the SGSN sends a load updating request to the data gateway and starts timing, wherein the load updating request carries the control plane connection information of the control network element;

and step 3, when the preset time is up, the SGSN releases the bearing resources.

Method six, in which a timer is conditionally timed after a voice handover to release resources. Specifically, the method can be realized by the following steps:

step 1, in a first switching process initiated by a control network element to an SGSN, if the control network element initiates the third switching process, sending a first switching completion confirmation message to the SGSN and waiting for a specific time, and then sending a non-voice-bearing third switching completion confirmation message, wherein the first switching completion confirmation message carries indication information;

and 2, after receiving the first switching completion confirmation message, the SGSN starts timing as the message carries the indication information, and releases the bearing resource when reaching the preset time or after receiving the bearing releasing message.

In the method, if the first handover completion acknowledgement message does not carry the indication information, timing is not performed, and the SGSN releases the bearer resource after receiving the bearer release message.

In the embodiment of the present invention, the media path may be updated not to bypass from the PS access network, and specifically, the following may be implemented: in the first switching process initiated by the control network element to the SGSN, the control network element sends a request for releasing the voice bearer to the PS access network after receiving the switching completion message, and sends a request for updating the bearer to the data gateway. Thereby releasing the bearing of the PS access network segment.

In a specific application, the SGSN may obtain the session media connection information from a control network element, and specifically, the method for the SGSN to obtain the session media connection information includes, but is not limited to, the following three methods:

in the first switching process, a control network element carries session media connection information in a switching request message (namely, a first switching request message) sent to an SGSN, and the SGSN can acquire the session media connection information through the switching request message;

method 2, controlling network element in the first switching process, carrying session media connection information in the first switching completion confirmation message and sending to SGSN, SGSN can obtain session media connection information through the switching completion confirmation message;

in the IMS session transfer process, the MSC sends a transfer request to the destination of the transfer number, and receives a temporary response message to the transfer request, where the temporary response message carries session media connection information; then, in the second handover process initiated by the control network element, the MSC carries the session media connection information in a second handover response or a second handover complete message (i.e. a handover complete message for the second handover process) sent to the control network element; then, the control network element carries the session media connection information in a first handover request message or a first handover completion confirmation message sent to the SGSN in a first handover process initiated to the SGSN, so that the SGSN can acquire the session media connection information carried in the first handover request or the second handover completion confirmation message.

In a specific application, the implementation of the method 1 and the method 2 has a premise that: the control network element obtains session media connection information, and in a specific application, the control network element can obtain the session media connection information through the UE. Specifically, after receiving a handover request sent by an access network, a control network element may obtain media resource information of a session to a UE, or the UE sends the media resource information of the session to the control network element when establishing the session, where the media resource information of the session includes: session media connection information, or session media connection information and codec information, so that the control network element can also obtain the session media connection information. Or, in some cases, the control network element locally stores the session media connection information, and the control network element may directly obtain the stored session media connection information without obtaining the session media connection information from the UE.

In the specific implementation process, after the IMS session transfer procedure is completed, the MSC further needs to release the media resource allocated in the second handover procedure.

The technical solutions provided by the embodiments of the present invention are described below by specific embodiments.

Example one

In this embodiment, a procedure in which an IMS voice call is established between a UE and a remote UE is described, a media connection is formed by a PS connection between the UE and a PS access network, a PS connection between the PS access network and a packet data gateway of the PS network, and an IP connection between the packet data gateway of the PS network and the remote UE, and the UE performs handover and the network implements single-mode service continuity. Fig. 6 is a flowchart of the present embodiment, and as shown in fig. 6, the method mainly includes the following steps:

step 601, the UE sends a Measurement report to the PS access network, for example, sends a Measurement report message, which includes signal strength information of the target network;

step 602, the PS access network determines to switch the UE call to the target network according to the signal strength, and sends a Handover request, for example, a Handover Required message to a control network element of the PS network;

step 603, the control network element determines that the UE establishes a bearer of the voice call, determines to switch the voice call to a CS domain of a target network, and obtains media resource Information of the session from the UE, for example, sending an ESM Information Request message to the UE, sending an ESM Information Response message by the UE, carrying codec Information of the session, or carrying codec Information of the session through a Service Request message in a session establishment initiating process of the UE, and the message sent by the UE may also carry media connection Information of the session, including media connection IP and port Information of the UE and the remote UE;

step 604, if the UE has other non-voice call services, the control network element sends a handover Request to the PS domain of the target network, and switches the services to the PS domain of the target network, for example, sends a Forward Relocation Request message to the PS domain of the target network, which carries other carried information.

Step 605, the control network element initiates a Handover process to the MSC at the same time, and first sends a Handover Request, for example, sends a PS to CS Handover Request message, which carries session media codec information and a forwarding number.

Step 606, the MSC performs the CS handover procedure to prepare CS media resources for the UE;

step 607, after the MSC completes the preparation process in the CS handover process, the MSC initiates an IMS session transfer process, and first initiates an INVITE message of a CS signaling SIP protocol or an INVITE message of an IMS signaling, the target is a transfer number, and carries media resource information of MGW controlled by the MSC, and the request is routed to an SCC AS in the IMS network;

step 608, at the same time as step 607, the MSC sends a Handover Response to the SGSN, for example, sends a PS to CS Handover Response message, which carries media information (i.e. the second media information) of the MGW controlled by the MSC, including media connection information of the MGW;

step 609, the control network element initiates a handover process to the SGSN for the voice bearer, and first sends a handover Request, for example, sends Forward location Request message, which carries the information of the voice bearer, the session media resource information, and the media information obtained in step 608, and if the UE in the session media resource information is not sent to the control network element, the control network element uses the session media connection information (included in the TFT information) of the voice bearer obtained in the voice bearer establishment process;

to this end, the SGSN may configure an encapsulated IP media connection address in the bearer to be established, that is, a local connection address of the encapsulated IP media connection is configured as that of the UE, and a remote connection address is configured as that of the remote UE.

Step 610, the SGSN sends a handover Response to a control network element of the PS network, for example, a Forward Relocation Response message, where the message carries bearer resource information of the SGSN and media information of the SGSN, including media connection information of the SGSN;

step 611, if the control network element also sends a handover request to the PS domain of the target network, the PS domain of the target network sends a handover response, for example, sends a Forward relocation response message, which carries the bearer resource information of the PS domain of the target network;

step 612, the control network element associates step 610 with step 611, and sends a Handover Command to the PS access network, for example, sends a Handover Command message, which carries the obtained bearer resource information;

step 613, the PS access network sends a Handover command to the UE, if the PS network is an LTE network, a Handover from LTE message is sent, and if the PS network is an HSPA network, a Handover from UTRAN message is sent;

step 614, the UE modulates to a target network, and the target network is informed;

step 615, the MSC receives a notification that the UE modulates to the target network or a link establishment response message sent by the MSC controlling the target cell, and sends a Handover completion message, such as a PS to CS Handover Complete message, to the control network element;

step 616, the control network element immediately sends a completion acknowledgement message to the MSC, for example, sends a PS to CS Handover Complete ACK message, carrying the media information (i.e. the first media information) obtained in step 610, so far, the MSC can exchange data with the SGSN through the IP media connection;

after receiving the message from step 616, the MSC can establish an IP media connection between the MGW and the SGSN under the control of the MSC.

Step 617, at the same time as step 616, the SGSN sends a handover Complete message, such as a Forward Relocation Complete message, to the control network element of the PS network;

step 618, if the media data is not desired to detour from the PS access network, the control network element sends a bearer release request to the PS access network to release the voice bearer resource in the PS access network;

step 619, after step 618, the controlling network element sends a bearer update request to the data gateway to update the bearer on the data gateway, so that the data gateway is directly connected with the SGSN;

step 620, if the control network element sends a handover request to the PS domain of the target network, the PS domain of the target network also sends a handover Complete message to the control network element, for example, a Forward Relocation Complete message;

to this end, a CS media connection and a transition media connection are established, where the transition media connection includes an uplink data media connection and a downlink data media connection, where the uplink media data connection is: MGW- > SGSN, SGSN- > data gateway controlled by MSC, data gateway- > remote UE; the downlink media data connection is: and the remote UE is more than the data gateway, the data gateway is more than the PS access network, the PS access network is more than the data gateway (if the steps 618-519 are executed, the two sections of connection between the data gateway and the PS access network are not available), and the data gateway is more than the SGSN and more than the MGW.

Step 621, after receiving the transfer request of step 608, the SCC AS associates the original session according to the number of the UE, and sends an UPDATE message to the remote UE of the original session, such AS a reINVITE message or an UPDATE message that sends an IMS signaling, and carries the media resource information obtained in step 608;

step 622, the remote UE responds to the update message, for example, sends a 200OK message, carrying new media resource information of the remote UE;

step 623, SCC AS receives the update response message, and sends a transfer response message to MSC, for example, sends 200OK message, which carries media resource information of remote UE;

step 624, the SCC AS releases the near-end access path of the original session, for example, sends the BYE message of the IMS, or if the UE has a PS domain after switching to the target network, the UE deletes the voice media connection of the original session, for example, sends the reINVITE message of the IMS, and carries the media resource information of the session of the UE, where the voice media resource information is identified AS invalid, for example, the port number is set to 0, these operations are all standard procedures, and the result causes the packet data gateway of the PS network to send an operation of deleting the voice bearer, if the packet data gateway is the HSPA network, the GGSN initiates, if the packet data gateway is the LTE network, the PGW sends the SGW, and then the SGW initiates the operation;

step 625, the packet data gateway (GGSN or SGW) of the PS network sends an operation of releasing the voice bearer to the control network element of the PS network, for example, sending a Delete bearerrrequest, which carries the voice bearer information;

step 626, the control network element sends a completion acknowledgement message to the SGSN, for example, a Forward Relocation Complete ACK message;

step 627, SGSN releases the bearing resource thereon;

step 628, if the control network element further sends a handover request to the PS domain of the target network, then further sends a completion acknowledgement message to the PS domain of the target network, for example, sends a ForwardRelocation Complete ACK message;

step 629, the PS domain of the target network sends an update Bearer message, e.g. send a Modify Bearer Request, to a packet data gateway (SGW) of the PS network to update the PS Bearer information, including the connection information of the control plane and the user plane.

And the final media path is CS media connection between the UE and the MGW controlled by the MSC and IP media connection between the MGW controlled by the MSC and the remote UE, and the near-end access path of the IMS signaling path is modified to be connected with the MSC.

Example two

In this embodiment, a procedure in which an IMS voice call is established between a UE and a remote UE is described, a media connection is formed by a PS connection between the UE and a PS access network, a PS connection between the PS access network and a packet data gateway of a PS network, and an IP connection between the packet data gateway of the PS network and the remote UE, and the UE performs handover and the network implements single-mode service continuity. Fig. 7 is a flowchart of the present embodiment, and as shown in fig. 7, the method mainly includes the following steps:

steps 701 to 702 are the same as steps 601 to 602 in fig. 6;

steps 703-706 are the same as steps 604-607 in FIG. 6;

step 707, the SCC AS receives the transfer request of step 707, and immediately sends a temporary response message, for example, sends a 183 Session Progress message of the IMS, which carries media resource information of the original Session, including media codec information of the original Session and Session media connection information, where the Session media connection information includes media connection address information of the UE and the remote UE;

step 708, the MSC sends a handover Response to the control network element, for example, sends a PS to CSHandover Response message, which carries media information of the MGW controlled by the MSC, including media connection information of the MGW, and also carries session media connection information obtained in step 707;

step 709, the control network element initiates a handover process to the SGSN for the voice bearer, and first sends a handover Request, for example, sends a Forward location Request message, which carries the voice bearer information and the media information and session media connection information obtained in step 708;

Steps 710 to 722 are the same as steps 610 to 622 in FIG. 6;

step 723, the SCC AS receives the UPDATE response of the remote UE, and sends an UPDATE message of the IMS to the MSC, such AS an UPDATE message, which carries the obtained media resource information of the remote UE;

step 724, the MSC sends an update response message, for example, a 200OK message of the CS signaling SIP protocol or a 200OK message of the IMS signaling, which carries media resource information of the MGW controlled by the MSC;

steps 725 to 731 are the same as steps 623 to 629 in FIG. 6.

EXAMPLE III

In this embodiment, the single mode service continuity only includes voice handover, in this embodiment, an IMS voice call is described to be established between the UE and the remote UE, and a non-voice connection is not established, the media connection is composed of a PS connection between the UE and the PS access network, a PS connection between the PS access network and the packet data gateway of the PS network, and an IP connection between the packet data gateway of the PS network and the remote UE, and the UE performs handover and the network implements the single mode service continuity, fig. 8 is an implementation flowchart of the present invention, which mainly includes the following steps:

step 801 is the same as steps 601 to 603 in FIG. 6, or the same as steps 701 to 702 in FIG. 7;

step 802, the control network element initiates a handover process to the SGSN for the voice bearer, and first sends a handover Request, for example, sends a Forward location Request message carrying information of the voice bearer and session media resource information, and in a specific application, if the UE does not send session media connection information in the session media resource information to the control network element, the control network element uses session media connection information (included in the TFT information) of the voice bearer obtained in the voice bearer establishment process;

step 803, at the same time as step 802, the control network element initiates a Handover process to the MSC, and first sends a Handover Request, for example, a PS to CS Handover Request message, which carries session media codec information and a forwarding number.

Step 804, if 801 uses the steps of FIG. 6, then it is the same as 606 ~ 608 of FIG. 6, otherwise it is the same as 705 ~ 708 of FIG. 7;

step 807, in Response to step 802, the SGSN sends a handover Response, such as a Forward Relocation Response message, to the control network element of the PS network, where the message carries bearer resource information of the SGSN and media information (i.e., first media information) of the SGSN, including media connection information of the SGSN;

step 808, if 801 uses the step of FIG. 6, the step is the same as 612 to 619 of FIG. 6, otherwise the step is the same as 712 to 719 of FIG. 7;

step 810, the control network element sends a completion confirmation message to the SGSN, for example, sends a Forward Relocation Complete ACK message, which carries the session media resource information and the media information (i.e. the second media information) obtained in step 804;

so far, the SGSN and the MSC negotiate the media connection information.

Step 811, if there is a non-voice bearer that is performing a handover operation, the target PS domain will also send a bearer update request to the data gateway, so the SGSN does not know whether the bearer update performed in step 804 can successfully update the control plane, and since the user plane updated by the SGSN is definitely different from the user plane updated by the target PS domain, the user plane can be successfully updated, so the SGSN starts a timer after receiving the completion confirmation message;

step 812, at the same time as step 811, the SGSN sends a Bearer update Request, such as a Modify Bearer Request message, to the data gateway according to a standard procedure;

to this end, a CS media connection and a transition media connection are established, where the transition media connection includes an uplink data media connection and a downlink data media connection, where the uplink media data connection is: MGW- > SGSN, SGSN- > data gateway, data gateway- > remote UE; the downlink media data connection is: remote UE- > data gateway, data gateway- > SGSN, SGSN- > MGW.

Since steps 618 to 519 in fig. 6 (or steps 718 to 719 in fig. 7) are executed in this embodiment, there are no two segments of connections, namely, a data gateway- > PS access network and a PS access network- > data gateway, in this embodiment.

Step 813 is the same as steps 621 to 624 of fig. 6 if step 801 uses the steps of fig. 6, otherwise is the same as steps 721 to 726 of fig. 7;

step 814, because only voice Bearer switching is performed, the update operation of step 812 updates the control plane of the data gateway, and the packet data gateway (GGSN or SGW) of the PS network sends an operation of releasing Bearer to the SGSN, such as sending a Delete Bearer Request, which carries voice Bearer information;

step 815, the SGSN receives the operation of releasing the bearer, or the timer in step 811 is overtime, and the SGSN releases the bearer resource.

Example four

In this embodiment, a flowchart for implementing a single mode service continuity, that is, a handover between voice and non-voice, is described, where an IMS voice call is established between a UE and a remote UE, and a non-voice connection is established, a media connection is formed by a PS connection between the UE and a PS access network, a PS connection between the PS access network and a packet data gateway of the PS network, and an IP connection between the packet data gateway of the PS network and the remote UE, and a process in which the UE performs a handover and the network implements a single mode service continuity is described. Fig. 9 is a flowchart of the present embodiment, and as shown in fig. 9, the method mainly includes the following steps:

step 901 is the same as steps 601 to 604 in fig. 6, in which step 604 is performed, or is the same as steps 701 to 703 in fig. 7, in which step 703 is performed;

step 902 is the same as 802-807 in FIG. 8;

step 903, if 901 uses the step of fig. 6, is the same as 611 to 616 of fig. 6, wherein step 611 is executed, otherwise is the same as 711 to 716 of fig. 7, wherein step 711 is executed;

step 904, the SGSN sends a handover Complete message, such as a Forward Relocation Complete message, to the control network element of the PS network;

step 905, if the media data is not expected to detour from the PS access network, the control network element sends a bearer release request to the PS access network to release the voice bearer resource in the PS access network;

step 906, after step 905, the control network element sends a bearer update request to the data gateway to update the bearer on the data gateway, so that the data gateway is directly connected with the SGSN;

step 907, because the non-voice-bearing handover operation is executed, the target PS domain also sends a handover Complete message, for example, a ForwardRelocation Complete message, to the control network element of the PS network;

step 908, after receiving the message of step 907, controlling the network element to start a timer;

step 909, at the same time as step 908, the control network element sends a switching completion acknowledgement message to the SGSN, for example, sends a Forward Relocation Complete Ack message, which carries the session media resource information and the media information obtained in step 902;

so far, the SGSN and the MSC negotiate the media connection information.

Step 910, if there is a non-voice bearer that is performing a handover operation, the target PS domain also sends a bearer update request to the data gateway, so the SGSN does not know whether the bearer update performed in step 911 can successfully update the control plane, and since the user plane updated by the SGSN is definitely different from the user plane updated by the target PS domain, the user plane can be successfully updated, and then the SGSN starts a timer after receiving the completion confirmation message;

step 911, at the same time as step 910, the SGSN sends a Bearer update Request to the data gateway according to a standard procedure, for example, sends a Modify Bearer Request message, or sends a Bearer update Request to the data gateway, carrying control plane information of the control network element, so as to avoid that the control network element cannot control the procedure due to a non-voice Bearer release operation occurring in a gap between steps 911 and 914;

the timer in step 912 and step 908 is overtime;

step 913, the control network element sends a handover Complete acknowledge message to the target PS domain, for example, sends a Forward Relocation Complete Ack message;

step 914, the target PS domain sends a Bearer update Request, such as a Modify Bearer Request message, to the data gateway according to the standard procedure;

the timer in step 908 is to ensure that the message in step 914 arrives at the data gateway later than the message in step 911.

To this end, a CS media connection and a transition media connection are established, where the transition media connection includes an uplink data media connection and a downlink data media connection, where the uplink media data connection is: MGW- > SGSN, SGSN- > data gateway, data gateway- > remote UE; the downlink media data connection is: and the remote UE is more than the data gateway, the data gateway is more than the PS access network, the PS access network is more than the data gateway (if the steps 905-906 are executed, the two sections of connection between the data gateway and the PS access network are not available), and the data gateway is more than the SGSN and more than the MGW.

Step 915, if 901 uses the step of FIG. 6, it is the same as 621-624 of FIG. 6, otherwise it is the same as 721-726 of FIG. 7;

the updating operation in step 916 and step 914 makes the control plane of the data gateway connect to the target PS domain, and the target PS domain does not control the voice bearer, so the data gateway does not forward the message of releasing the voice bearer to the SGSN, and when the timer in step 910 times out, the SGSN releases the bearer resource.

EXAMPLE five

In this embodiment, the procedure of establishing an IMS voice call between the UE and the remote UE is described, where the media connection is composed of a PS connection between the UE and the PS access network, a PS connection between the PS access network and a packet data gateway of the PS network, and an IP connection between the packet data gateway of the PS network and the remote UE, and the UE performs handover and the network implements single-mode service continuity. Fig. 10 is a flowchart of the present embodiment, and as shown in fig. 10, the method mainly includes the following steps:

step 1001 is the same as steps 601 to 604 in FIG. 6, or the same as steps 701 to 703 in FIG. 7;

step 1001a is the same as 802 to 807 in FIG. 8;

step 1001b, if 901 uses the step of fig. 6, it is the same as 611-616 of fig. 6, otherwise it is the same as 711-716 of fig. 7;

step 1002, the SGSN sends a handover Complete message, such as a Forward Relocation Complete message, to a control network element of the PS network;

step 1003, if the media data is not desired to bypass from the PS access network, the control network element sends a bearer release request to the PS access network to release the voice bearer resource in the PS access network;

after step 1004 and step 1003, the control network element sends a bearer update request to the data gateway to update the bearer on the data gateway, so that the data gateway is directly connected with the SGSN;

step 1005, because the non-voice bearing switching operation may be executed, the target PS domain may also send a switching completion message, such as Forward Relocation Complete message, to the control network element of the PS network;

step 1006, after receiving the message of step 1002, if the non-voice bearer switching operation is executed, controlling the network element to start a timer;

step 1007, the control network element sends a switching completion acknowledgement message to the SGSN, for example, sends a Forward Relocation Complete Ack message, which carries the session media resource information and the media information obtained in step 1001 a;

so far, the SGSN and the MSC negotiate the media connection information.

Step 1008, the SGSN receives the switching completion confirmation message, if the message carries the indication information, the timer is started, otherwise the timer is not started;

step 1009, if the message in step 1007 does not carry indication information, the SGSN sends a bearer update request to the data gateway according to a standard procedure, for example, sends a Modify bearer request message, otherwise, the SGSN sends a bearer update request to the data gateway according to the standard procedure, or sends a bearer update request to the data gateway, and carries control plane information of the control network element, so as to avoid that the control network element cannot control the procedure due to a non-voice bearer release operation occurring in a gap between step 1009 and possibly step 1012;

step 1010, if step 1006 is executed, the timer in step 1006 times out;

step 1011, if the non-voice-bearing switching operation is executed, the control network element sends a switching completion confirmation message to the target PS domain, for example, sends a Forward relocation complete Ack message;

step 1012, the target PS domain sends a Bearer update Request, such as a Modify Bearer Request message, to the data gateway according to the standard procedure;

the timer in step 1006 ensures that the message in step 1012 arrives at the data gateway later than the message in step 1009.

To this end, a CS media connection and a transition media connection are established, where the transition media connection includes an uplink data media connection and a downlink data media connection, where the uplink media data connection is: MGW- > SGSN, SGSN- > data gateway, data gateway- > remote UE; the downlink media data connection is: and the remote UE is more than the data gateway, the data gateway is more than the PS access network, the PS access network is more than the data gateway (if the steps 1003-1004 are executed, the two sections of connection between the data gateway and the PS access network are not available), and the data gateway is more than the SGSN and more than the MGW.

Step 1013, if 1001 uses the step of FIG. 6, it is the same as the steps 621 to 624 of FIG. 6, otherwise it is the same as the steps 721 to 726 of FIG. 7;

step 1014, if the non-voice bearer switching operation is not executed, and step 1009 is executed according to the standard procedure, the data gateway will send the voice bearer release request to the SGSN;

step 1015, the SGSN receives the operation of releasing the bearer, or the timer of step 1008 times out, and the SGSN releases the bearer resource.

EXAMPLE six

In this embodiment, the procedure of establishing an IMS voice call between the UE and the remote UE is described, where the media connection is composed of a PS connection between the UE and the PS access network, a PS connection between the PS access network and a packet data gateway of the PS network, and an IP connection between the packet data gateway of the PS network and the remote UE, and the UE performs handover and the network implements single-mode service continuity. Fig. 11 is a flowchart of the present embodiment, and as shown in fig. 11, the method mainly includes the following steps:

step 1101 is the same as steps 601 to 617 in FIG. 6, or the same as steps 701 to 717 in FIG. 7;

step 1104, after receiving the handover complete message sent by the SGSN, the control network element starts a timer;

step 1105, if the media data is not desired to detour from the PS access network, the control network element sends a bearer release request to the PS access network to release the voice bearer resource in the PS access network;

step 1106 and step 1105, the controlling network element sends a bearer update request to the data gateway to update the bearer on the data gateway, so that the data gateway is directly connected to the SGSN;

step 1107, if the control network element sends a handover request to the PS domain of the target network, the PS domain of the target network also sends a handover Complete message, such as Forward Relocation Complete message, to the control network element;

step 1108, the control network element receives the handover Complete message sent to the PS domain of the target network, and sends a sending Complete confirmation message, such as a ForwardRelocation Complete ACK message, to the PS domain of the target network;

step 1109, the PS domain of the target network sends an update Bearer message, for example, sends a Modify Bearer Request, to a packet data gateway (SGW) of the PS network, so as to update PS Bearer information, including connection information of the control plane and the user plane.

Step 1110 is the same as steps 621 to 624 in FIG. 6, or steps 721 to 726 in FIG. 7;

the timer in step 1111 and step 1104 is overtime;

step 1112, the control network element sends a handover Complete acknowledge message to the SGSN, for example, sends a Forward Relocation Complete Ack message;

step 1113, SGSN releases the load bearing resource.

EXAMPLE seven

In this embodiment, the procedure of establishing an IMS voice call between the UE and the remote UE is described, where the media connection is composed of a PS connection between the UE and the PS access network, a PS connection between the PS access network and a packet data gateway of the PS network, and an IP connection between the packet data gateway of the PS network and the remote UE, and the UE performs handover and the network implements single-mode service continuity. Fig. 12 is a flowchart of the present embodiment, and as shown in fig. 12, the method mainly includes the following steps:

step 1201 is the same as steps 601 to 604 in FIG. 6, or the same as steps 701 to 703 in FIG. 7;

step 1201a is the same as 802 to 807 in FIG. 8;

step 1201b, if the step of FIG. 6 is used in 1201, the same as 611 to 616 of FIG. 6, otherwise the same as 711 to 716 of FIG. 7;

step 1202, the SGSN sends a handover Complete message, such as a Forward Relocation Complete message, to a control network element of the PS network;

step 1203, if the media data is not desired to detour from the PS access network, the control network element sends a bearer release request to the PS access network to release the voice bearer resource in the PS access network;

after step 1204 and step 1203, the control network element sends a bearer update request to the data gateway to update the bearer on the data gateway, so that the data gateway is directly connected to the SGSN;

step 1205, because the non-voice-bearing handover operation may be executed, the target PS domain may also send a handover completion message, such as Forward Relocation Complete message, to the control network element of the PS network;

step 1206, the control network element sends a handover Complete acknowledge message to the SGSN, for example, sends a Forward Relocation Complete Ack message, carrying the session media resource information and the media information obtained in step 1201 a;

so far, the SGSN and the MSC negotiate the media connection information.

Step 1207, the SGSN receives the switching completion confirmation message and starts a timer;

step 1208, if the non-voice bearer switching operation is executed, the control network element sends a switching completion acknowledgement message to the target PS domain, for example, sends a Forward relocation complete Ack message;

step 1209, the target PS domain sends a Bearer update Request, such as a Modify Bearer Request message, to the data gateway according to the standard procedure;

to this end, a CS media connection and a transition media connection are established, where the transition media connection includes an uplink data media connection and a downlink data media connection, where the uplink media data connection is: MGW- > SGSN, SGSN- > data gateway, data gateway- > remote UE; the downlink media data connection is: and the remote UE is more than the data gateway, the data gateway is more than the PS access network, the PS access network is more than the data gateway (if the steps 1203 to 1204 are executed, the two sections of connection between the data gateway and the PS access network are not available), and the data gateway is more than the SGSN and more than the MGW.

Step 1210, if 1201 uses the step of FIG. 6, then it is the same as steps 619 to 624 of FIG. 6, otherwise it is the same as steps 719 to 726 of FIG. 7;

the timer in step 1211 and step 1207 is expired, and the SGSN releases the bearer resource.

The following describes an SGSN provided in an embodiment of the present invention.

Fig. 13 is a schematic structural diagram of an SGSN according to an embodiment of the present invention, and as shown in fig. 13, the SGSN mainly includes: a handover processing module 10, configured to establish a bearer between the SGSN and the data gateway through a first handover procedure initiated by a control network element for a voice bearer of the UE, negotiate media information and obtain session media connection information through the first handover procedure, and transmit the established bearer information, the media connection information indicated by the media information, and the session media connection information to a connection mapping module 30; a connection mapping module 30, configured to perform association storage on the carried information and the media connection information, and store session media connection information; a data packing module 50, configured to receive media data on the media connection, pack the media data onto the bearer according to the bearer information associated with the media connection and stored in the connection mapping module 30, and set connection information of the media data packed on the bearer according to the session media connection information stored in the connection mapping module 30.

Further, as shown in fig. 13, the SGSN further includes: a data unpacking module 70, configured to receive the media data on the bearer, and unpack the media data into the media connection according to the information of the media connection associated with the bearer, which is stored by the connection mapping module 30.

Preferably, as shown in fig. 14, the switching processing module 10 includes: a receiving unit 100, configured to receive a handover complete confirmation message sent by a control network element in a first handover process; a resource releasing unit 102, configured to release the bearer resource of the voice bearer after the receiving unit 100 receives the handover completion confirmation message.

Further, as shown in fig. 14, the handover processing module 10 may further include: and a timer 104 for timing, and triggering the resource releasing unit 102 when a predetermined time is reached.

Further, the handover processing module 10 may further include: a sending unit 106, configured to send a bearer update request to the data gateway, where the bearer update request carries control plane connection information of the control network element; the timer 104 may be started when the sending unit 100 sends a bearer update request or when the receiving unit 106 receives a handover complete acknowledge message.

Fig. 15 is a schematic structural diagram of a controlling network element according to an embodiment of the present invention, and as shown in fig. 15, the controlling network element mainly includes: the receiving module 20, the first handover processing module 40 and the second handover processing module 60. The receiving module 20 is configured to receive a handover request sent by an access network, and trigger the first handover processing module 40 and the second handover processing module 60 when receiving the handover request; a first switching processing module 40, configured to initiate a first switching process to the SGSN for voice bearer, acquire first media information through the first switching process, and send second media information to the SGSN; the second switching processing module 60 is configured to initiate a second switching process to the MSC, send the forwarding number and the first media information to the MSC through the second switching process, and acquire the second media information.

Wherein the first media information includes: media connection information of the SGSN; the second media information includes: MSC controlled MGW media connection information.

From the above description, it can be seen that, the SGSN encapsulates the IP media data transferred by the MGW controlled by the MSC to the bearer between the packet data gateway of the PS network and the SGSN, thereby implementing single mode service continuity, partitioning the CS domain function and the PS domain function of the MSC, avoiding the problem of switching the IMS signaling bearer, and solving the problem of control plane update of the packet data gateway of the PS network.

It will be apparent to those skilled in the art that the modules or steps of the present invention described above may be implemented by a general purpose computing device, they may be centralized on a single computing device or distributed across a network of multiple computing devices, and alternatively, they may be implemented by program code executable by a computing device, such that they may be stored in a storage device and executed by a computing device, and in some cases, the steps shown or described may be performed in an order different than that described herein, or they may be separately fabricated into individual integrated circuit modules, or multiple ones of them may be fabricated into a single integrated circuit module. Thus, the present invention is not limited to any specific combination of hardware and software.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for implementing single mode service continuity is characterized by comprising the following steps:

after receiving a handover request sent by an access network, a control network element initiates a first handover procedure to a serving GPRS support node SGSN for voice bearer, and obtains first media information through the first handover procedure, where the first media information includes: media connection information of the SGSN;

the control network element initiates a second switching process to a Mobile Switching Center (MSC), sends a transfer number to the MSC through the second switching process, and obtains second media information, wherein the second media information comprises: media connection information of a media gateway MGW controlled by the MSC;

the MSC initiates an IMS session transfer process by taking the transfer number as a target and executes a CS switching process;

the control network element sends the second media information to the SGSN through the first switching process, and sends the first media information to the MSC through the second switching process;

the SGSN acquires session media connection information and sets connection information of media data according to the session media connection information, wherein the media data is packaged in a bearer established through the first switching process.

2. The method of claim 1, wherein during the first handover procedure initiated for the voice bearer, the method further comprises:

after receiving a message for releasing voice bearer and a first switching completion message sent by the SGSN, the control network element sends a first switching completion confirmation message to the SGSN, and if the control network element initiates a third switching process for non-voice bearer, the control network element simultaneously sends a third switching completion confirmation message for the non-voice bearer;

and after receiving the first switching completion confirmation message, the SGSN releases the bearing resources.

3. The method of claim 1, wherein during the first handover procedure initiated for the voice bearer, the method further comprises:

the control network element receives a first switching completion message sent by the SGSN and waits for a preset time, and then sends a first switching completion confirmation message to the SGSN;

4. The method of claim 1, wherein during the first handover procedure initiated for the voice bearer, the method further comprises:

and the SGSN releases the bearing resource after receiving the first switching completion confirmation message sent by the control network element and waiting for preset time.

5. The method of claim 1, wherein if the controlling network element initiates a third handover procedure for a non-voice bearer, the method further comprises:

the control network element sends a third switching completion confirmation message for non-voice bearing after sending a first switching completion confirmation message to the SGSN and waiting for a preset time;

and the SGSN receives the first switching completion confirmation message and releases the bearing resources after waiting for preset time or receiving the bearing releasing message.

6. The method of claim 1, wherein if the controlling network element initiates a third handover procedure for a non-voice bearer, the method further comprises:

after receiving the first handover completion confirmation message, the SGSN sends a bearer update request to a data gateway, where the bearer update request carries control plane connection information of the control network element;

and the SGSN releases the bearing resources after waiting for the preset time.

7. The method of claim 1, wherein if the controlling network element initiates a third handover procedure for a non-voice bearer, the method further comprises:

the control network element sends a first switching completion confirmation message to the SGSN and sends a third switching completion confirmation message for the non-voice bearer after waiting for a preset time, wherein the first switching completion confirmation message carries indication information;

and the SGSN receives the first switching completion confirmation message and releases the bearing resources after waiting for a specific time or receiving the bearing releasing message.

8. The method of claim 1, wherein after the controlling network element receives a first handover complete message during the first handover procedure, the method further comprises:

and the control network element sends a request for releasing the voice bearer to the PS access network and sends a request for updating the bearer to the data gateway.

9. The method of claim 1, wherein the SGSN acquiring the session media connection information comprises:

in the first switching process, the control network element carries the session media connection information in a first switching request message or a first switching completion confirmation message sent to the SGSN;

and the SGSN acquires the session media connection information carried in the first switching request message or the first switching completion confirmation message.

10. The method of claim 9,

before the controlling network element sends the first handover request message to the SGSN, the method further includes: the control network element acquires media resource information of a session from the UE after receiving the switching request from the access network; or,

before the controlling network element sends the first handover complete confirm message, the method further comprises: the UE sends the media resource information of the session to the control network element when establishing the session;

wherein the media resource information of the session includes: the session media connection information, or the session media connection information and codec information.

11. The method of claim 1, wherein the SGSN acquiring session media connection information comprises:

in the IMS session transfer process, the MSC sends a transfer request and receives a temporary response message of the transfer request, wherein the temporary response message carries the session media connection information;

in the second handover process, the MSC carries the session media connection information in a second handover response or a second handover complete message sent to the control network element;

the control network element carries the session media connection information in a first switching request or a first switching completion confirmation message sent to the SGSN;

and the SGSN acquires the session media connection information carried in the first switching request or first switching completion confirmation message.

12. The method of claim 1, wherein after the IMS session transfer procedure is completed, the method further comprises:

the MSC releases the media resources allocated in the second handover procedure.

13. A system for implementing single-mode service continuity, comprising:

a control network element, configured to initiate a first handover procedure to an SGSN for voice bearer after receiving a handover request sent by an access network, initiate a second handover procedure to an MSC, obtain first media information in the first handover procedure, send second media information to the SGSN, send a transfer number and the first media information to the MSC in the second handover procedure, and obtain the second media information; the first media information includes: media connection information of the SGSN; the second media information includes: media connection information of a media gateway MGW controlled by the MSC;

the SGSN is configured to acquire the second media information through the first handover procedure, send the first media information, and set connection information of media data according to session media connection information acquired through the first handover procedure, where the media data is encapsulated in a bearer established in the first handover procedure;

and the MSC is used for initiating an IMS session transfer process by taking the transfer number as a target in the second switching process, executing a CS switching process, acquiring the first media information through the second switching process and sending the second media information.

14. The system of claim 13,

the control network element is further configured to send a first handover complete confirmation message to the SGSN after receiving a message for releasing a voice bearer and a first handover complete message sent by the SGSN in the first handover process, and send a third handover complete confirmation message for a non-voice bearer simultaneously if the control network element initiates a third handover process for the non-voice bearer;

the SGSN is further configured to release the bearer resource after receiving the first handover complete confirm message.

15. The system of claim 13,

the control network element is further configured to send a first handover complete confirmation message to the SGSN after receiving a first handover complete message sent by the SGSN and waiting for a predetermined time in the first handover process;

the SGSN is further configured to release the bearer resource after receiving the first handover complete confirm message in the first handover procedure.

16. An SGSN, comprising:

a switching processing module, configured to establish a bearer between the SGSN and a data gateway for a first switching process initiated by a voice bearer through a control network element, negotiate media information and obtain session media connection information through the first switching process, and transmit the established bearer information, the media connection information indicated by the media information, and the session media connection information to a connection mapping module;

the connection mapping module is used for storing the carried information and the media connection information in a correlation manner and storing session media connection information;

the data packing module is configured to receive media data on the media connection, package the media data onto the bearer according to the bearer information associated with the media connection and stored by the connection mapping module, and set connection information of the media data packaged on the bearer according to the session media connection information stored by the connection mapping module.

17. The SGSN of claim 16, wherein said SGSN further comprises:

and the data unpacking module is used for receiving the media data on the bearer and unpacking the media data into the media connection according to the information of the media connection related to the bearer, which is stored by the connection mapping module.

18. The SGSN of claim 16, wherein said first handover processing module comprises:

a receiving unit, configured to receive a handover completion confirmation message sent by the control network element in the first handover process;

and the resource releasing unit is used for releasing the bearing resource of the voice bearing after the receiving unit receives the switching completion confirmation message.

19. The SGSN of claim 18, wherein said first handover processing module further comprises:

the timer is used for timing and triggering the resource release unit when the preset time is reached;

a sending unit, configured to send a bearer update request to a data gateway, where the bearer update request carries control plane connection information of the control network element;

the timer is started when the sending unit sends the bearer update request or when the receiving unit receives the handover completion confirmation message.

20. A controlling network element, comprising:

the receiving module is used for receiving a switching request sent by an access network and triggering the first switching processing module and the second switching processing module when the switching request is received;

the first switching processing module is used for initiating a first switching process to the SGSN for voice bearing, acquiring first media information through the first switching process and sending second media information to the SGSN; the first media information includes: media connection information of the SGSN; the second media information includes: media connection information of media gateway MGW controlled by MSC;

the second switching processing module is configured to initiate a second switching process to an MSC, send a forwarding number and the first media information to the MSC through the second switching process, and acquire the second media information.