CN108574670A - Switching method and system of a kind of IMS call to circuit domain - Google Patents

Switching method and system of a kind of IMS call to circuit domain Download PDF

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Publication number
CN108574670A
CN108574670A CN201710141541.XA CN201710141541A CN108574670A CN 108574670 A CN108574670 A CN 108574670A CN 201710141541 A CN201710141541 A CN 201710141541A CN 108574670 A CN108574670 A CN 108574670A
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China
Prior art keywords
vmscs
atcf
emscs
ims
refers
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CN201710141541.XA
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Chinese (zh)
Inventor
刘竞翔
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ZTE Corp
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ZTE Corp
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Priority to CN201710141541.XA priority Critical patent/CN108574670A/en
Priority to PCT/CN2018/077037 priority patent/WO2018161804A1/en
Publication of CN108574670A publication Critical patent/CN108574670A/en
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
    • H04L65/1066—Session management
    • H04L65/1083—In-session procedures
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
    • H04L9/40—Network security protocols
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
    • H04L65/10—Architectures or entities
    • H04L65/1016—IP multimedia subsystem [IMS]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
    • H04L65/10—Architectures or entities
    • H04L65/102—Gateways
    • H04L65/1023—Media gateways
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
    • H04L65/10—Architectures or entities
    • H04L65/1046—Call controllers; Call servers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
    • H04L65/1066—Session management
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
    • H04L65/1066—Session management
    • H04L65/1101—Session protocols
    • H04L65/1104—Session initiation protocol [SIP]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0011—Control or signalling for completing the hand-off for data sessions of end-to-end connection
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/14—Reselecting a network or an air interface

Abstract

The invention discloses the switching method and system of a kind of IMS calls to circuit domain, method includes：Just when a user terminal of IMS calls is moved to the only position of circuit-domain network from packet field network, what vMSCS received eMSCS transmissions includes the preparation switching request for the STN SR numbers that recognition purpose address is ATCF；VMSCS establishes the multimedia link to ATCF using the STN SR numbers in the preparation switching request, so that one user terminal with another user terminal just conversed in IMS by the way that when vMSCS is accessed and is switched to circuit-domain network, IMS calls are carried out via the multimedia link.

Description

Switching method and system of a kind of IMS call to circuit domain
Technical field
The present invention relates to handoff technique field of conversing in communication network, more particularly to a kind of IMS (IP Multimedia Subsystem, IP multimedia subsystem) it converses to the switching method and system of circuit domain.
Background technology
Talk business is a kind of basic service that IMS network is provided, and the user of IMS calls is carried out, generally from LTE (Long Term Evolution, long term evolution) network insertion.And when user is moved to only CS (Circuit Switch, electricity Road exchange) network when, need SRVCC (the Single Radio Voice Call for carrying out the network from LTE to CS Continuity, single wireless voice calling continuity).As shown in Figure 1.
UE A are the UE to switch.
EMSCS (Enhanced Mobile Switch Center Server, enhance Mobile Switching Center Server) is The mobile switch server of process switching.The eMSCS provides switching service for UE A, and provides Call- Control1 work(after handover Energy.
MME (Mobility Management Entity, mobility management entity) is pipes of the UE A in packet-switched domain Manage network element.UE A before the handover, are resided under MME, and the IP connections provided by MME, are connected to S-CSCF (Serving- Call Session Control Function, service call conversation control function).When needing to be switched to circuit domain, MME MSC (Mobile Switching Center, mobile switching centre) is sent a handover request to, completion switching stream is interacted with MSC Journey.
S-CSCF is the S-CSCF that service is provided for UE A.
SCC AS (Service Centralization and Continuity Application Server, business Concentrate and continuous application server) be in IMS network provide call continuity service AS (Application Server, are answered With server).
UE B are the distal ends with UE A dialogues.
MGW-1 (Media Gateway-1, Media Gateway -1) is the Media Gateway under eMSCS.
VMSCS (Visiting Mobile Switch Center Server, Visited Mobile Switching Center server) is Mobile switch server after switching where UE.UE is accessed in vMSCS, and signaling passes through MSCMAP (MSC Mobile Application Part, MSC mobile application section) interface is sent to eMSCS processing.
MGW-2 (Media Gateway-2, Media Gateway -2) is the Media Gateway under vMSCS.
ATCF (Access Transfer Control Function access conversion and control function) auxiliary SCC AS are provided Business continuance, in handoff procedure, ATCF can be used as anchor point, reduce the signalling time delay of switching.
ATGW (Access Transfer Gateway access transfer gateway) is the Media Gateway under ATCF, to switch work( Anchor point on media can be provided.Before switching, media link is UE A-ATGW-UE B, and after switching, media link becomes UE A- MGW2-MGW1-ATGW-UE B。
As shown in Fig. 2, being the flow for carrying out SRVCC switchings.
UE A under step 201.LTE call UE B, carry out IMS calls.In communication process, UE A are moved to circuit domain Network, therefore by handover decisions, determine to switch over.
Step 202.MME sends a handover request to eMSCS, it is desirable that switches over, is carried to ATCF's in switching request Routing number STN-SR (Session Transfer Number-Single Radio, single-frequency Session Hand-off number).
Step 203. receive the eMSCS of request by MAP interfaces send Prepare Handover Request message to vMSCS。
Step 204.vMSCS applies for media resource on MGW2, the media connection for switching.
After step 205., vMSCS carries out the switching preparation of wireless side, applies for radio resource.
Step 206.vMSCS sends Prepare Handover Response message to eMSCS, as predecessor request Response, and carry the Handover Number of itself distribution.Handover Number establishes switching speech channel for eMSCS to vMSCS.
Step 207. receives the media resource on eMSCS applications MGW1 after response.
Step 208.eMSCS is route using Handover Number, establishes the speech channel to vMSCS, sends IAM (Identity And Access Management, identification are managed with accessing) message is to vMSCS.
Step 209.vMSCS returns to ACM (address complete message, address full information), and both sides' speech channel is built It is vertical.
Step 210.eMSCS sends INVITE message to ATCF, begins setting up the speech channel of ATCF.INVITE is with above-mentioned STN-SR is destination address, and carries the media resource information applied on MGW1.
Step 211.eMSCS returns to switching response to MME simultaneously, and notice MME resources are ready to complete.
Step 212.MME sends switching command and begins to transfer to circuit-domain network access to UE A, UE A.
Step 213. receives the ATCF of INVITE message, applies for the media resource on ATGW.
Step 214.ATCF returns to 200OK, carries the media information of ATGW.
At the same time, the UE for receiving switching command completes access to step 215. on vMSCS.
Step 216.vMSCS sends Send End Signal Request to eMSCS, and notice switching is completed.
VMSCS sends ANM (Anwser Message, response message) message to step 217. simultaneously, completes between eMSCS Speech channel establish process.Media arrive MGW1, then arrive ATGW from UE A to MGW2 at this time, finally arrive UE B and form connection.
The eMSCS transmissions that step 218. receives message handoff completion message to MME, and notice MME switchings have been completed.
Step 219.ATCF is interacted after returning to 200OK between SCC AS, updates dialogue between the two.
After the completion of above-mentioned SRVCC handoff procedures, the Media Stream of the sides UE A will have passed through MGW1, MGW2, ATGW tri- A node could arrive the sides UE B.And multiple forwarding, it is clear that transmission path can be extended, consume transfer resource, and increase voice The risk that quality reduces.
Invention content
The technical issues of scheme provided according to embodiments of the present invention solves is that IMS callings are switched to from LTE network access It is needed by multiple forwarding in circuit-domain network access, it is long to cause transmission path, and transmission resource consumption is big and voice matter Amount reduces.
A kind of IMS provided according to embodiments of the present invention converses to the switching method of circuit domain, including：
Just when a user terminal of IMS calls is moved to the only position of circuit-domain network from packet field network, What vMSCS received eMSCS transmissions includes the preparation switching request for the STN-SR numbers that recognition purpose address is ATCF；
VMSCS establishes the multimedia link to ATCF using the STN-SR numbers in the preparation switching request, with toilet A user terminal is stated by being accessed in vMSCS and when being switched to circuit-domain network, via the multimedia link with just in IMS Another user terminal of call carries out IMS calls；
Wherein, the IMS refers to IP multimedia subsystem；The vMSCS refers to Visited Mobile Switching Center server；Institute It refers to enhancing Mobile Switching Center Server to state eMSCS；The ATCF is to refer to the accession to conversion and control function；The STN-SR refers to Single-frequency Session Hand-off number.
Preferably, the vMSCS establishes the multimedia to ATCF using the STN-SR numbers in the preparation switching request Link includes：
When the vMSCS is established to the multimedia link of ATCF, the interface message for establishing the multimedia link is determined；
If it is determined that establish the multimedia link interface message be SIP (Session Initiation Protocol, Session initiation protocol) interface, then the vMSCS is sent to ATCF includes the invite message of STN-SR numbers；
If it is determined that the interface message for establishing the multimedia link is BICC (Bearer Independent Call Control protocol, the call control protocol unrelated with carrying) interface, then it includes STN- that the vMSCS is sent to ATCF The IAM message of SR numbers；
Wherein, the SIP session initiation protocols；The BICC refers to the call control protocol unrelated with carrying；The IAM Refer to that identification is managed with access.
Preferably, further include the addresses eMSCS in the invite message that the vMSCS is sent to ATCF, make the invite Message is transmitted to ATCF via eMSCS.
A kind of IMS provided in an embodiment of the present invention converses to the switching method of circuit domain, including：
Just when a user terminal of IMS calls is moved to the only position of circuit-domain network from packet field network, EMSCS receives the response message for including MGW2 media resources that vMSCS is returned by sending invite message to vMSCS；
By sending the invite message for including MGW2 media resources to ATCF, receive ATCF returns includes eMSCS The response message of ATGW media resources；
EMSCS makes vMSCS believe using the ATGW media resources by the way that the ATGW media resources are sent to vMSCS Breath, establishes the multimedia link of the MGW2 to the ATGW, so that one user terminal in vMSCS by accessing, cuts When changing to circuit-domain network, IMS calls are carried out with another user terminal just conversed in IMS via the multimedia link；
Wherein, the IMS refers to IP multimedia subsystem；The vMSCS refers to Visited Mobile Switching Center server；Institute It refers to enhancing Mobile Switching Center Server to state eMSCS；The MGW2 refers to Media Gateway 2；The ATCF is to refer to the accession to conversion Control function；The ATGW is to refer to the accession to transfer gateway.
Preferably, for the eMSCS by sending invite message to vMSCS, receive vMSCS returns includes MGW2 media Before the response message of resource, further include：
EMSCS prepares switching request by being sent to vMSCS, and vMSCS is made to apply for MGW2 media resources to the MGW2 of management.
A kind of IMS provided in an embodiment of the present invention converses to the switching system of circuit domain, including：
VMSCS, for being just moved to only circuit-domain network from packet field network in a user terminal of IMS calls When position, receive eMSCS transmissions includes the preparation switching request for the STN-SR numbers that recognition purpose address is ATCF, and The multimedia link to ATCF is established using the STN-SR numbers in the preparation switching request；
ATCF, for by establishing multimedia link between the vMSCS, one user terminal being made to pass through When vMSCS is accessed and is switched to circuit-domain network, via the multimedia link and just in another user terminal of IMS calls Carry out IMS calls；
Wherein, the IMS refers to IP multimedia subsystem；The vMSCS refers to Visited Mobile Switching Center server；Institute It refers to enhancing Mobile Switching Center Server to state eMSCS；The ATCF is to refer to the accession to conversion and control function；The STN-SR refers to Single-frequency Session Hand-off number.
Preferably, the vMSCS is specifically used for when establishing to the multimedia link of ATCF, and the multimedia is established in determination The interface message of link, however, it is determined that the interface message for establishing the multimedia link is SIP interface, then described sent to ATCF is wrapped The invite message of the number containing STN-SR, however, it is determined that the interface message for establishing the multimedia link is BICC interfaces, then described VMSCS sends the IAM message for including STN-SR numbers to ATCF；
Wherein, the SIP session initiation protocols；The BICC refers to the call control protocol unrelated with carrying；The IAM Refer to that identification is managed with access.
Preferably, further include the addresses eMSCS in the invite message that the vMSCS is sent to ATCF, make the invite Message is transmitted to ATCF via eMSCS.
A kind of IMS provided in an embodiment of the present invention converses to the switching system of circuit domain, including：
EMSCS, for being just moved to only circuit-domain network from packet field network in a user terminal of IMS calls When position, by vMSCS transmission invite message, receiving the response message for including MGW2 media resources that vMSCS is returned, and By sending the invite message for including MGW2 media resources to ATCF, the answering comprising ATGW media resources that ATCF is returned is received Message is answered, and the ATGW media resources are sent to vMSCS；
VMSCS sends to the eMSCS and is provided comprising MGW2 media for the invite message by receiving the eMSCS The response message in source, and using the ATGW media resources of eMSCS transmissions, establish more matchmakers of the MGW2 to the ATGW Body link, so that one user terminal is by when vMSCS is accessed, and is switched to circuit-domain network, via the multimedia Link carries out IMS calls with another user terminal just conversed in IMS；
ATCF, for by the invite message for including MGW2 media resources by receiving the eMSCS, to described EMSCS sends the response message for including ATGW media resources；
Wherein, the IMS refers to IP multimedia subsystem；The vMSCS refers to Visited Mobile Switching Center server；Institute It refers to enhancing Mobile Switching Center Server to state eMSCS；The MGW2 refers to Media Gateway 2；The ATCF is to refer to the accession to conversion Control function；The ATGW is to refer to the accession to transfer gateway.
Preferably, the eMSCS is specifically used for preparing switching request by sending to vMSCS, makes vMSCS to management MGW2 applies for MGW2 media resources.
The scheme provided according to embodiments of the present invention realizes in SRVCC functions, without disposing MGW's under eMSCS network elements Target reduces the lower deployment cost of system, the efficiency and the voice quality after switching for improving SRVCC switchings.
Description of the drawings
A kind of network structure for the SRVCC functions that Fig. 1 prior arts provide；
Fig. 2 is the SRVCC switching flow figures that the prior art provides；
Fig. 3 is a kind of flow chart of switching method one of the IMS calls provided in an embodiment of the present invention to circuit domain；
Fig. 4 is a kind of flow chart of switching method two of the IMS calls provided in an embodiment of the present invention to circuit domain；
Fig. 5 is a kind of schematic diagram of switching system one of the IMS calls provided in an embodiment of the present invention to circuit domain；
Fig. 6 is a kind of schematic diagram of switching system two of the IMS calls provided in an embodiment of the present invention to circuit domain；
Fig. 7 is the SRVCC switching flow figures provided in an embodiment of the present invention using scheme one；
Fig. 8 is the SRVCC switching flow figures provided in an embodiment of the present invention using scheme two.
Specific implementation mode
Below in conjunction with attached drawing to a preferred embodiment of the present invention will be described in detail, it should be understood that described below is excellent Select embodiment only for the purpose of illustrating and explaining the present invention and is not intended to limit the present invention.
Fig. 3 is a kind of flow chart of switching method one of the IMS calls provided in an embodiment of the present invention to circuit domain, such as Fig. 3 It is shown, including：
Step S301：Just only circuit-domain network is moved to from packet field network in a user terminal of IMS calls When position, vMSCS receives being asked comprising the preparation switching for the STN-SR numbers that recognition purpose address is ATCF for eMSCS transmissions It asks；
Step S302：VMSCS establishes the multimedia chain to ATCF using the STN-SR numbers in the preparation switching request Road, so that one user terminal in vMSCS by accessing and when being switched to circuit-domain network, via the multimedia link IMS calls are carried out with another user terminal just conversed in IMS；
Wherein, the IMS refers to IP multimedia subsystem；The vMSCS refers to Visited Mobile Switching Center server；Institute It refers to enhancing Mobile Switching Center Server to state eMSCS；The ATCF is to refer to the accession to conversion and control function；The STN-SR refers to Single-frequency Session Hand-off number.
Wherein, the vMSCS establishes the multimedia chain to ATCF using the STN-SR numbers in the preparation switching request Road includes：When the vMSCS is established to the multimedia link of ATCF, the interface message for establishing the multimedia link is determined；If Determine that the interface message for establishing the multimedia link is SIP interface, then it includes STN-SR numbers that the vMSCS is sent to ATCF Invite message；If it is determined that the interface message for establishing the multimedia link is BICC interfaces, then the vMSCS is sent out to ATCF Send the IAM message for including STN-SR numbers.
Wherein, further include the addresses eMSCS in the invite message that the vMSCS is sent to ATCF, the invite is made to disappear Breath is transmitted to ATCF via eMSCS.
Fig. 4 is a kind of flow chart of switching method two of the IMS calls provided in an embodiment of the present invention to circuit domain, such as Fig. 4 It is shown, including：
Step S401：Just only circuit-domain network is moved to from packet field network in a user terminal of IMS calls When position, eMSCS receives the response comprising MGW2 media resources that vMSCS is returned and disappears by sending invite message to vMSCS Breath；
Step S402：EMSCS receives ATCF and returns by sending the invite message for including MGW2 media resources to ATCF The response message for including ATGW media resources；
Step S403：EMSCS makes vMSCS utilize the ATGW matchmaker by the way that the ATGW media resources are sent to vMSCS Body resource information establishes the multimedia link of the MGW2 to the ATGW, so that one user terminal passes through in vMSCS Access when being switched to circuit-domain network, is carried out via the multimedia link with another user terminal just conversed in IMS IMS converses；
Wherein, the IMS refers to IP multimedia subsystem；The vMSCS refers to Visited Mobile Switching Center server；Institute It refers to enhancing Mobile Switching Center Server to state eMSCS；The MGW2 refers to Media Gateway 2；The ATCF is to refer to the accession to conversion Control function；The ATGW is to refer to the accession to transfer gateway.
Wherein, the eMSCS receives being provided comprising MGW2 media for vMSCS returns by sending invite message to vMSCS Before the response message in source, further include：EMSCS prepares switching request by being sent to vMSCS, makes MGW2s of the vMSCS to management Apply for MGW2 media resources.
Fig. 5 is a kind of schematic diagram of switching system one of the IMS calls provided in an embodiment of the present invention to circuit domain, such as Fig. 5 It is shown, including：VMSCS501, for being just moved to only circuit domain from packet field network in a user terminal of IMS calls When the position of network, receive eMSCS transmissions includes the preparation switching for the STN-SR numbers that recognition purpose address is ATCF Request, and establish the multimedia link to ATCF using the STN-SR numbers in the preparation switching request；ATCF502 is used for By establishing multimedia link between the vMSCS, so that one user terminal is passed through and accessed in vMSCS and be switched to electricity When the network of road domain, IMS calls are carried out with another user terminal just conversed in IMS via the multimedia link；Wherein, institute It refers to IP multimedia subsystem to state IMS；The vMSCS refers to Visited Mobile Switching Center server；The eMSCS refers to enhancing Mobile Switching Center Server；The ATCF is to refer to the accession to conversion and control function；The STN-SR refers to single-frequency Session Hand-off number Code.
Wherein, the vMSCS501 is specifically used for when establishing to the multimedia link of ATCF, and more matchmakers are established in determination The interface message of body link, however, it is determined that the interface message for establishing the multimedia link is SIP interface, then described to be sent to ATCF Include the invite message of STN-SR numbers, however, it is determined that the interface message for establishing the multimedia link is BICC interfaces, then institute It states vMSCS and sends the IAM message for including STN-SR numbers to ATCF；Wherein, the SIP session initiation protocols；The BICC is Refer to the call control protocol unrelated with carrying；The IAM refers to that identification is managed with access.
Wherein, further include the addresses eMSCS in the invite message that the vMSCS501 is sent to ATCF, make the invite Message is transmitted to ATCF via eMSCS.
Fig. 6 is a kind of schematic diagram of switching system two of the IMS calls provided in an embodiment of the present invention to circuit domain, such as Fig. 6 It is shown, including：EMSCS601, for being just moved to only circuit domain from packet field network in a user terminal of IMS calls When the position of network, by sending invite message to vMSCS, the response for including MGW2 media resources that vMSCS is returned is received Message, and by sending the invite message for including MGW2 media resources to ATCF, receive ATCF returns includes ATGW media The response message of resource, and the ATGW media resources are sent to vMSCS；VMSCS602, for by receiving the eMSCS Invite message, sent to the eMSCS and include the response messages of MGW2 media resources, and utilize eMSCS transmissions ATGW media resources, establish the multimedia link of the MGW2 to the ATGW, so as to one user terminal by VMSCS is accessed, when being switched to circuit-domain network, via the multimedia link and just in another user terminal of IMS calls Carry out IMS calls；ATCF603, the invite message for including MGW2 media resources for receiving the eMSCS by passing through, The response message for including ATGW media resources is sent to the eMSCS；Wherein, the IMS refers to IP multimedia subsystem；It is described VMSCS refers to Visited Mobile Switching Center server；The eMSCS refers to enhancing Mobile Switching Center Server；The MGW2 It refer to Media Gateway 2；The ATCF is to refer to the accession to conversion and control function；The ATGW is to refer to the accession to transfer gateway.
Wherein, the eMSCS601 is specifically used for preparing switching request by sending to vMSCS, makes vMSCS to management MGW2 applies for MGW2 media resources.
The embodiment of the present invention includes two schemes：
Scheme one：
EMSCS carries above-mentioned STN-SR in the Prepare Handover Request for being sent to vMSCS.
VMSCS is after receiving above-mentioned Prepare Handover Request, using STN-SR as destination address, establishes To the speech channel of ATCF.
Speech channel is not established between eMSCS and vMSCS.
Speech channel after the completion of foundation, to ATGW, eliminates the MGW1 under eMSCS from UE to MGW2.
Further, vMSCS is established to when ATCF speech channels, if using SIP interface, sends INVITE message. The Request URI (Uniform Resource Identifier, uniform resource identifier) of INVITE message are STN-SR. If using BICC interfaces, IAM message is sent, the called number in IAM message is STN-SR.
Further, eMSCS carries the address of itself in Prepare Handover Request message.Typically, The form of TelURI or SIPURI may be used in this address, can also use the form of E.164 number.
Further, if using SIP interface, the Route header fields of INVITE message should include the address of eMSCS.Make INVITE message reaches ATCF again by eMSCS.EMSCS can be made to be inserted into speech channel in this way, obtain necessary Call- Control1 power.
Fig. 7 is the SRVCC switching flow figures provided in an embodiment of the present invention using scheme one, as shown in fig. 7, working as eMSCS When using SIP interface between vMSCS, including：
UE A under step 701.LTE call UE B, carry out IMS calls.In communication process, UE A are moved to circuit domain Network, therefore by handover decisions, determine to switch over.
Step 702.MME sends a handover request to eMSCS, it is desirable that switches over, is carried to ATCF's in switching request Routing number STN-SR.
Step 703. receive the eMSCS of request by Map interfaces send Prepare Handover Request message to vMSCS.Above-mentioned STN-SR numbers are carried in Prepare Handover Request.
Step 704. receives Prepare Handover Request message, and vMSCS applies for media resource on MGW2, uses It is connected in the media of switching.
After step 705., vMSCS carries out the switching preparation of wireless side, applies for radio resource.
Step 706.vMSCS sends INVITE message, and destination address therein is above-mentioned STN-SR numbers, and In Route header fields, it is inserted into the address of above-mentioned eMSCS.And in INVITE message, the IMSI of switching user is carried (International Mobile Subscriber Identification Number, international mobile subscriber identity) is marked Know.
Step 707.INVITE message is all to be first routed to eMSCS network elements because Route header fields have the address of eMSCS. EMSCS is by the IMSI in INVITE message, by the dialogue of INVITE and handoff association.P-s of the eMSCS in INVITE message Asserted-Identity header fields fill in MSISDN (the Mobile Subscriber International ISDN/ of user PSTN number, mobile subscriber's International ISDN/PSTN numbers) number, INVITE message is then continued to route into ATCF.
Step 708.vMSCS sends Prepare Handover Response message to eMSCS after INVITE.By In media connection need not be established between eMSCS and vMSCS, so Prepare Handover Response message is not taken Band Handover Number.
The eMSCS that step 709. receives Prepare Handover Response message returns to switching response to MME.
Step 710.MME sends switching command and begins to transfer to circuit-domain network access to UE A, UE A.
At the same time step 711., receives and applies for media resource on ATCF to the ATGW of INVITE message.
Step 712.ATCF returns to media resource information in 200OK, and message is first passed around according to transmitting path eMSCS。
Step 713.eMSCS continues 200OK to be forwarded to vMSCS.After vMSCS receives 200OK message, vMSCS is accomplished to Process is established in media connection between ATCF.
On the other hand, the UE for receiving switching command completes access to step 714. on vMSCS.
Step 715.vMSCS sends Send End Signal Request to eMSCS, and notice switching is completed.
Step 716.eMSCS transmissions handoff completion message to MME, and notice MME handoff procedures terminate.
Step 717.ATCF is interacted after returning to 200OK between SCC AS, update both and between pair Words.
Scheme two,
SIP interface is used between vMSCS and eMSCS.
EMSCS sends INVITE message after receiving the Prepare Handover Response message of vMSCS, Media information is not carried in INVITE message.Therefore, eMSCS need not apply for media resource from MGW1.
VMSCS receives INVITE, returns to SIP response messages.SIP response messages can be 180,183 or 200OK. The media information that vMSCS applies in MGW2 is carried in message.
EMSCS receives message, sends INVITE to ATCF, the media information of above-mentioned MGW2 is carried in INVITE.
ATCF returns to the media information of ATGW according to the prior art in the response to eMSCS.
The media information of ATGW is returned to vMSCS by eMSCS in 180,183 or 200 response message.
Using this flow, direct-connected media connection is established between the MGW2 and ATGW at vMSCS.It can be under eMSCS No longer dispose MGW.
Fig. 8 is the SRVCC switching flow figures provided in an embodiment of the present invention using scheme two, as shown in figure 8, including：
UE A under step 801.LTE call UE B, carry out IMS calls.In communication process, UE A are moved to circuit domain Network, therefore by handover decisions, determine to switch over.
Step 802.MME sends a handover request to eMSCS, it is desirable that switches over, is carried to ATCF's in switching request Routing number STN-SR.
Step 803. receive the eMSCS of request by Map interfaces send Prepare Handover Request message to vMSCS。
Step 804.vMSCS applies for media resource on MGW2, the media connection for switching.
After step 805., vMSCS carries out the switching preparation of wireless side, applies for radio resource.
Step 806.vMSCS sends Prepare Handover Response message to eMSCS, as predecessor request Response, and carry the Handover Number of itself distribution.Handover Number establishes switching speech channel for eMSCS to vMSCS.
EMSCS sends INVITE message to vMSCS after step 807. receives response.Due to there is no MGW under eMSCS, so In the INVITE message, SDP (Session Description Protocol, Session Description Protocol) media information is not carried.
Step 808.vMSCS receives INVITE message, returns to 180 message, and SDP Offer, mark are carried in 180 message Media information on local terminal MGW2.
Step 809.eMSCS receives 180 message, sends INVITE message to ATCF, ATCF is using above-mentioned STN-SR as target Address, and carry the media resource information of one end vMSCS in above-mentioned 180 message.
Step 810.eMSCS returns to switching response to MME, notice MME resources have prepared after sending INVITE message At.
Step 811.MME sends switching command and begins to transfer to circuit-domain network access to UE A, UE A.
Step 812. simultaneously, receives the ATCF of INVITE message, applies for the media resource on ATGW.
Step 813.ATCF returns to 200OK, carries the media information of ATGW.
Step 814.eMSCS receives 200OK message, sends the response message PRACK (Provisional of above-mentioned 180 message Response ACKnowledgement, Temporary Response confirm), the media of the ATGW in wherein carrying above-mentioned 200OK message Information.
Step 815.vMSCS receives the media information of PRACK and ATGW therein, complete between such vMSCS and ATCF At the exchange of media information, the two can establish media connection.The vMSCS of PRACK message is received, ACK message is returned and carries out Confirm.
Step 816. above process carries out simultaneously, and UE completes access at vMSCS.
Step 817.vMSCS sends Send End Signal Request to eMSCS, and notice switching is completed.
VMSC sends 200OK message to step 818. simultaneously, and process is established in the speech channel completed between eMSCS.
The eMSCS transmissions that step 819. receives message handoff completion message to MME, and notice MME switchings have been completed.
Step 820.ATCF is interacted after returning to 200OK between SCC AS, updates dialogue between the two.
The scheme provided according to embodiments of the present invention can reduce the media gateway node after the completion of SRVCC processes, shorten Transmission path improves voice quality.
Although describing the invention in detail above, but the invention is not restricted to this, those skilled in the art of the present technique It can be carry out various modifications with principle according to the present invention.Therefore, all to be changed according to made by the principle of the invention, all it should be understood as Fall into protection scope of the present invention.

Claims (10)

1. a kind of IMS converses to the switching method of circuit domain, including：
Just when a user terminal of IMS calls is moved to the only position of circuit-domain network from packet field network, vMSCS connects Receive eMSCS transmissions includes the preparation switching request for the STN-SR numbers that recognition purpose address is ATCF；
VMSCS establishes the multimedia link to ATCF using the STN-SR numbers in the preparation switching request, so as to described one A user terminal via the multimedia link and just in IMS by when vMSCS is accessed and is switched to circuit-domain network, conversing Another user terminal carry out IMS calls；
Wherein, the IMS refers to IP multimedia subsystem；The vMSCS refers to Visited Mobile Switching Center server；It is described EMSCS refers to enhancing Mobile Switching Center Server；The ATCF is to refer to the accession to conversion and control function；The STN-SR refers to list Frequency Session Hand-off number.
2. switching method according to claim 1, the vMSCS utilizes the STN-SR numbers in the preparation switching request The multimedia link for establishing ATCF includes：
When the vMSCS is established to the multimedia link of ATCF, the interface message for establishing the multimedia link is determined；
If it is determined that the interface message for establishing the multimedia link is SIP interface, then it includes STN- that the vMSCS is sent to ATCF The invite message of SR numbers；
If it is determined that the interface message for establishing the multimedia link is BICC interfaces, then the vMSCS includes to ATCF transmissions The IAM message of STN-SR numbers；
Wherein, the SIP session initiation protocols；The BICC refers to the call control protocol unrelated with carrying；The IAM refers to Identification is managed with access.
3. switching method according to claim 2, further include in the invite message that the vMSCS is sent to ATCF The addresses eMSCS make the invite message be transmitted to ATCF via eMSCS.
4. a kind of IMS converses to the switching method of circuit domain, including：
Just when a user terminal of IMS calls is moved to the only position of circuit-domain network from packet field network, eMSCS is logical It crosses to vMSCS and sends invite message, receive the response message for including MGW2 media resources that vMSCS is returned；
For eMSCS by sending the invite message for including MGW2 media resources to ATCF, that receive ATCF returns includes ATGW matchmaker The response message of body resource；
EMSCS makes vMSCS utilize the ATGW media resource informations, builds by the way that the ATGW media resources are sent to vMSCS The multimedia link of the vertical MGW2 to the ATGW is switched to electricity so that one user terminal in vMSCS by accessing When the network of road domain, IMS calls are carried out with another user terminal just conversed in IMS via the multimedia link；
Wherein, the IMS refers to IP multimedia subsystem；The vMSCS refers to Visited Mobile Switching Center server；It is described EMSCS refers to enhancing Mobile Switching Center Server；The MGW2 refers to Media Gateway 2；The ATCF is to refer to the accession to conversion control Function processed；The ATGW is to refer to the accession to transfer gateway.
5. switching method according to claim 4, the eMSCS is received by sending invite message to vMSCS Before the response message comprising MGW2 media resources that vMSCS is returned, further include：
EMSCS prepares switching request by being sent to vMSCS, and vMSCS is made to apply for MGW2 media resources to the MGW2 of management.
6. a kind of IMS converses to the switching system of circuit domain, including：
VMSCS, the position for being just moved to only circuit-domain network from packet field network in a user terminal of IMS calls When, receive eMSCS transmissions includes the preparation switching request for the STN-SR numbers that recognition purpose address is ATCF, and is utilized STN-SR numbers in the preparation switching request establish the multimedia link to ATCF；
ATCF, for by establishing multimedia link between the vMSCS, one user terminal being made to pass through in vMSCS When accessing and being switched to circuit-domain network, carried out with another user terminal just conversed in IMS via the multimedia link IMS converses；
Wherein, the IMS refers to IP multimedia subsystem；The vMSCS refers to Visited Mobile Switching Center server；It is described EMSCS refers to enhancing Mobile Switching Center Server；The ATCF is to refer to the accession to conversion and control function；The STN-SR refers to list Frequency Session Hand-off number.
7. switching system according to claim 6, the vMSCS is specifically used for establishing the multimedia link to ATCF When, determine the interface message for establishing the multimedia link, however, it is determined that the interface message for establishing the multimedia link connects for SIP Mouthful, then it is described that the invite message for including STN-SR numbers is sent to ATCF, however, it is determined that establish the interface of the multimedia link Information is BICC interfaces, then the vMSCS sends the IAM message for including STN-SR numbers to ATCF；
Wherein, the SIP session initiation protocols；The BICC refers to the call control protocol unrelated with carrying；The IAM refers to Identification is managed with access.
8. switching system according to claim 7, further include in the invite message that the vMSCS is sent to ATCF The addresses eMSCS make the invite message be transmitted to ATCF via eMSCS.
9. a kind of IMS converses to the switching system of circuit domain, including：
EMSCS, the position for being just moved to only circuit-domain network from packet field network in a user terminal of IMS calls When, by sending invite message to vMSCS, receive vMSCS returns includes the response message of MGW2 media resources, and passes through The invite message for including MGW2 media resources is sent to ATCF, is received the response comprising ATGW media resources that ATCF is returned and is disappeared Breath, and the ATGW media resources are sent to vMSCS；
VMSCS is sent to the eMSCS comprising MGW2 media resources for the invite message by receiving the eMSCS Response message, and using the ATGW media resources of eMSCS transmissions, establish the multimedia chain of the MGW2 to the ATGW Road, so that one user terminal is by when vMSCS is accessed, and is switched to circuit-domain network, via the multimedia link IMS calls are carried out with another user terminal just conversed in IMS；
ATCF, the invite message for including MGW2 media resources for receiving the eMSCS by passing through, to the eMSCS Send the response message for including ATGW media resources；
Wherein, the IMS refers to IP multimedia subsystem；The vMSCS refers to Visited Mobile Switching Center server；It is described EMSCS refers to enhancing Mobile Switching Center Server；The MGW2 refers to Media Gateway 2；The ATCF is to refer to the accession to conversion control Function processed；The ATGW is to refer to the accession to transfer gateway.
10. switching system according to claim 9, the eMSCS is specifically used for asking by sending to prepare to switch to vMSCS It asks, vMSCS is made to apply for MGW2 media resources to the MGW2 of management.
CN201710141541.XA 2017-03-10 2017-03-10 Switching method and system of a kind of IMS call to circuit domain Withdrawn CN108574670A (en)

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