WO2010108447A1 - 单无线接入方式语音切换的实现方法及系统 - Google Patents

单无线接入方式语音切换的实现方法及系统 Download PDF

Info

Publication number
WO2010108447A1
WO2010108447A1 PCT/CN2010/071328 CN2010071328W WO2010108447A1 WO 2010108447 A1 WO2010108447 A1 WO 2010108447A1 CN 2010071328 W CN2010071328 W CN 2010071328W WO 2010108447 A1 WO2010108447 A1 WO 2010108447A1
Authority
WO
WIPO (PCT)
Prior art keywords
handover
radio access
session
media
network
Prior art date
Application number
PCT/CN2010/071328
Other languages
English (en)
French (fr)
Inventor
郝振武
游世林
谢振华
陶全军
谢宝国
Original Assignee
中兴通讯股份有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 中兴通讯股份有限公司 filed Critical 中兴通讯股份有限公司
Publication of WO2010108447A1 publication Critical patent/WO2010108447A1/zh

Links

Classifications

    • 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
    • H04W36/0022—Control or signalling for completing the hand-off for data sessions of end-to-end connection for transferring data sessions between adjacent core network technologies
    • H04W36/00224—Control or signalling for completing the hand-off for data sessions of end-to-end connection for transferring data sessions between adjacent core network technologies between packet switched [PS] and circuit switched [CS] network technologies, e.g. circuit switched fallback [CSFB]
    • H04W36/00226—Control or signalling for completing the hand-off for data sessions of end-to-end connection for transferring data sessions between adjacent core network technologies between packet switched [PS] and circuit switched [CS] network technologies, e.g. circuit switched fallback [CSFB] wherein the core network technologies comprise IP multimedia system [IMS], e.g. single radio voice call continuity [SRVCC]

Definitions

  • the present invention relates to the field of communications, and in particular, to a method and system for implementing voice switching in a single wireless access mode.
  • the third generation (3G) mobile communication network such as Global System for Mobile communications (GSM), Universal Mobile Communication System (Universal Mobile Telecommunications System (UMTS), which uses the Circuit Switch (CS) method to provide voice services
  • GSM Global System for Mobile communications
  • UMTS Universal Mobile Telecommunications System
  • IP Internet Protocol
  • the entire network evolves toward all-IP.
  • the core network of the communication network to the IP Multimedia Subsystem IP Multimedia Core Network Subsystem
  • IMS evolution IP Multimedia Core Network Subsystem
  • the wireless access network develops to packet switching, and carries voice and other services through a packet switching (PS) network, and can directly access the IMS, and the IMS provides voice services, including voice services. Communication business.
  • PS packet switching
  • IMS IP-based network architecture proposed by the 3rd Generation Partnership Project (3GPP). It builds an open and flexible business environment that is independent of access and can support multimedia applications. Provide users with rich multimedia services.
  • 3GPP 3rd Generation Partnership Project
  • 3GPP proposes a next-generation network architecture for Long Term Evolution/System Architecture Evolution (LTE/SAE), which uses packet switching technology to provide more
  • LTE/SAE Long Term Evolution/System Architecture Evolution
  • the high transmission rate and the shorter transmission delay can carry real-time services including voice services, which can be used as an access method of the IMS network, and the IMS provides services.
  • the Home NodeB (referred to as the Home NodeB) system, which is a micro-cell access method proposed by the 3GPP, including a ⁇ access node and a ⁇ gateway.
  • the ⁇ access node is deployed in a place where macrocell signals such as buildings are difficult to reach, and the signal coverage is relatively large. Area, sharing the traffic volume of the user indoors or in a specific area.
  • the HNB system is connected to the UE through the CS user interface, and then accesses the existing CS core network to implement voice services.
  • the HNB function can also be used to directly connect the IP address to the IMS.
  • the deployment of access technologies is a gradual process. For example, during the deployment of LTE/SAE, operators may only cover in hotspots in the initial stage. Some access methods are applicable to local deployments, such as HNB. The system's coverage is limited to small areas such as homes and buildings. Since this paper focuses on the user's access from these local coverage areas and the continuity of voice services in the case of voice services, these local coverage areas are called source wireless access coverage areas.
  • FIG. 1 is a service scenario of voice switching (also referred to as voice continuity) in the above scenario.
  • voice switching also referred to as voice continuity
  • the user When the user conducts voice services in the source wireless access coverage area, the user directly accesses the IMS and establishes an IMS session with the remote user.
  • the CS network When the user moves out of the coverage area, in order to ensure the continuity of the voice service, the CS network is switched, and the session anchor function in the IMS is used to maintain the continuity of the call with the remote user, so that the advantages of the CS network coverage can be fully utilized. , to ensure the continuity of business.
  • the user's mobile device can only access a wireless network while in a call state.
  • a wireless network For example, for an LTE/SAE user equipment, only the LTE/SAE network can be accessed before the handover, and not simultaneously.
  • CS network When moving to the CS network coverage area, the wireless connection with LTE/SAE must be disconnected to access the CS network. This access method is called single wireless access mode.
  • the wireless access mode before and after the handover is the CS mode.
  • the core network is different because it is connected to the IMS.
  • FIG. 2 is a schematic structural diagram of voice switching in a single wireless access mode.
  • control layer In the IMS service system, the control layer is separated from the service layer.
  • the control layer does not provide specific services. It only provides the necessary triggering, routing, and accounting functions to the service layer.
  • the service triggering and control function in the control layer is completed by the call session control function 205 (CSCF).
  • CSCF call session control function 205
  • the service layer is composed of a series of application servers (Application Servers, AS for short).
  • the control layer controls the service trigger according to the subscription information of the user, and invokes the service on the AS to implement the service function.
  • the Service Continuity Control AS (SCC AS) is responsible for anchoring the signaling path of the session, so it is called signaling.
  • a Media Gateway Control Function (MGCF) and a Media Gateway (MGW) 207 are constructed at the IMS edge, and the MGCF completes the relationship between the CS signaling and the IMS signaling. Interworking and switching, and controlling the MGW to complete the conversion between the CS bearer and the IMS bearer.
  • MGCF Media Gateway Control Function
  • MGW Media Gateway
  • the Interworking Gateway (IWG) 204 is designed to support single radio access. Basically, based on the functions of the Mobile Switching Center (MSC) Server, the handover support function is added and passed between the MSC Servers.
  • the interface is connected to the target CS network 203, and communicates with the IMS through the MGCF/MGW 207, and is connected to the source radio access network 202 through the interface, and receives the handover request of the source radio access network to complete the handover.
  • the IWG 204 can be further enhanced to include the functions of the MGCF and the MGW, and directly access the IMS from the SIP interface, and does not need to pass through the MGCF/MGW.
  • the user equipment 201 accesses the source radio access network 202 through the Uu interface, and accesses the IMS network through the SGi interface, and carries control signaling and media streams on the interface.
  • the control signaling uses the Session Initial Protocol (SIP), and its path is shown by the dotted line in Figure 2.
  • SIP Session Initial Protocol
  • the SIP session path of UE 201 and remote UE 208 is triggered by S-CSCF 205 to SCC AS 206 and anchored at SCC AS 206, which provides session control and traffic.
  • a media path is established between the UE 201 and the remote UE 208 under the control of the above control path.
  • the Uu interface is CS access signaling and media
  • the source wireless access network converts the CS access signaling and media into IMS signaling and media, and then accesses the IMS.
  • FIG. 3 is a schematic diagram of a handover process in a single radio access mode in the prior art.
  • the UE When the UE accesses the IMS from the source wireless network and enters the call state, the UE periodically detects the surrounding wireless environment, and notifies the source wireless access network through the measurement report;
  • the source wireless access network checks the current wireless communication condition according to the local configuration, and if it is found that the currently used wireless access is no longer suitable for communication, for example, if the signal strength is lower than the set threshold, the surrounding area will be reported from the UE.
  • the source radio access network discovers that the communication medium includes voice, sends a CS handover request to the IWG, and carries information such as cell information, user identifier, and session transfer number (STN) of the target CS network, and notifies the IWG to perform handover. Go to step 305;
  • step 303 if the communication medium also contains non-speech PS media, and the target network and the terminal support both CS and PS access, send a PS handover request to the target PS network, go to step 306;
  • the IWG receives the handover request of the source radio access network, completes the process of radio resource preparation and circuit connection by using the existing handover mechanism of the CS, and then sends a session handover request to the IMS through the MGCF/MGW to establish an inbound call branch instead.
  • the cut-out call branch established by the source radio access network realizes access branch switching and updates the media connection with the remote end;
  • the target PS network receives the PS handover request, and completes the PS handover preparation process.
  • the IWG After the step 305 is completed, the IWG returns a CS handover response to the source radio access network, indicating that the handover preparation is completed, and carries the handover information.
  • the target PS network After the step 306 is complete, the target PS network returns a PS handover response to the source radio access network, indicating that the handover preparation is complete, and carrying the handover information.
  • the source radio access network receives the CS handover response in step 307 and the PS handover response in step 308, and knows that the target network is ready to be sent, and sends a handover command to the UE.
  • the UE performs handover and switches to the target network.
  • the source wireless access network sends a handover command to the UE, indicating that the UE switches to the target CS network, and completes the access-side handover process to ensure that the session is not interrupted.
  • the voice interruption time is required to be no more than 300ms.
  • FIG. 4 is a flow chart of switching in a single radio access mode in the prior art.
  • the UE-A accesses the source radio access coverage area, accesses the IMS through the source radio access network, and establishes an IMS session with the remote UE-B.
  • the signaling path of the session is anchored by the SCC AS, and the media path is from the UE.
  • -A is connected to the UE-B via the source radio access network.
  • the signaling path of the source access includes two ends: UE to SCC
  • the source signaling access path also referred to as the cut-out access branch
  • the remote signaling access branch of the AS and the original media path is an IMS bearer.
  • the UE-A periodically reports the wireless measurement report to the source wireless access network, where the report includes measurement data of the currently used wireless access mode and measurement data of the surrounding wireless access mode.
  • the source radio access network performs a handover decision according to the reported radio measurement report.
  • the radio condition of the radio access mode being used by the UE-A is deteriorated, for example, when the UE-A receives the signal strength lower than the set handover threshold, and the CS access is more suitable for communication, it is decided to switch the bearer to the CS network. .
  • the source radio access network sends a CS handover request to the IWG, carrying the user identifier, the target.
  • Cell information of the CS network and handover routing information (such as the identifier of the STN and the SCC AS);
  • the IWG determines a target MSC Server where the target CS cell is located, and sends a handover preparation request to the target MSC Server.
  • the target MSC Server forwards the handover preparation request to the target radio subsystem (RNS/BSS, Radio Network Subsystem/Base Station Subsystem, radio network subsystem/base station subsystem);
  • RNS/BSS Radio Network Subsystem/Base Station Subsystem, radio network subsystem/base station subsystem
  • the target radio subsystem reserves radio resources according to the indication of the handover preparation request, and returns a handover preparation response to the target MSC Server, and carries detailed information of the target radio access network.
  • a target bearer - CS bearer 2 is established between the target MSC Server and the target radio subsystem.
  • the target MSC Server sends a handover preparation response to the IWG.
  • the preparation process of the handover is completed by the CS switching preparation process of the standard 403 to 407 standard.
  • the IWG establishes a circuit connection with the target MSC Server.
  • the target bearer - CS bearer 3 is established between the IWG and the target MSC Server. 409.
  • the IWG uses the handover identifier STN as the called number, and uses the initial address message (Initial).
  • the address message (IAM) message sends a handover request to the IMS, requesting the SCC AS to perform the handover process; This step can be performed after step 407 and executed in parallel with step 408.
  • the MGCF converts the IAM into a SIP Invite message (INVITE) message, and sends the message to the SCC AS through a network element such as the CSCF, and carries the media resource information provided by the MGW described by the Session Description Protocol (SDP);
  • SIP Invite message IVSITE
  • SDP Session Description Protocol
  • the MGW starts the local media receiving port indicated in the media resource information, and prepares to receive the media stream sent by the peer end;
  • the SCC AS sends a SIP media update request (RE-INVITE) to the remote UE-B, and carries the media resource information provided by the MGW obtained in step 410.
  • RE-INVITE SIP media update request
  • the UE-B returns a SIP acknowledgment response, and carries the media resource information of the UE-B response.
  • the acknowledgment response may be a final acknowledgment response (200 OK), or may be a temporary response. If it is a temporary response, the subsequent response may be similar.
  • Media negotiation process may be a final acknowledgment response (200 OK), or may be a temporary response. If it is a temporary response, the subsequent response may be similar.
  • the UE-B starts the local media receiving port indicated in the media resource information, and prepares to receive the media stream sent by the peer end; the local media receiving port may use the media receiving port that is originally used, or may allocate a new media receiving port; If a new media receiving port is used, the two ports are simultaneously received. When the media received by the new port is closed, the original media receiving port is closed, so that the media is not lost during the port changing process. At this time, since the UE-A is still in the source radio access network, the UE-B can continue to receive the media stream sent by the UE-A, that is, the answering is not affected.
  • the UE will change the sending direction of the media stream, send the media to the receiving port specified in step 411, that is, the media receiving port of the MGW, and stop transmitting the media to the media receiving port of the UE-A.
  • the UE-A cannot receive the media.
  • the media stream sent by UE-B is that user A cannot hear user B's voice.
  • the SCC AS forwards the 200 OK to the MGCF, and carries the media resource information of the UE-B response.
  • the MGCF/MGW and the UE-B establish the IMS bearer of the target bearer. At this time, although the path that the MGW sends the media stream to the UE-B has been established, since the UE-A has not been switched, there is actually no media stream.
  • the MGCF sends an Answer Message (ANM) response to the IWG.
  • NAM Answer Message
  • the IMS session switching process is completed, and the media update of the remote UE is established, and the target wireless subsystem-target MSC Server is established.
  • - MGCF/MGW - UE-B The target media is hosted between.
  • the original bearer transmits and receives the media, and the transmitting medium of the UE-B has switched to the target bearer, but the media can still be received at the original port, so starting from step 412 from the UE-
  • the media stream from A to UE-B is normal (referred to as the uplink media stream), and the media stream interruption from UE-B to UE-A (referred to as the downlink media stream) is expressed as a single pass.
  • the MGCF returns a SIP acknowledgement request (ACK) to the SCC AS at the same time;
  • the SCC AS sends an ACK acknowledgement message to the UE-B.
  • the IWG sends a CS handover response to the source radio access network, and carries detailed wireless information of the target CS access obtained in step 407.
  • the source radio access network sends a handover command to the UE-A, indicating that the UE-A switches to the designated target CS network.
  • UE-A performs a wireless handover process, cuts into a specified target CS network, and establishes signaling and media connection with the target wireless subsystem.
  • the UE-A switches to the target CS wireless network, and establishes a target bearer between the UE-A and the target wireless subsystem: CS bearer 1 to complete the access side handover, establish a media connection with the remote UE-B, and the call resumes normal.
  • CS bearer 1 to complete the access side handover
  • UE-B receives the media stream from the receiving port of the target bearer. If the receiving port of the source bearer is different from the receiving port of the target bearer, UE-B will close the receiving port of the source bearer.
  • the target wireless subsystem detects that the UE successfully accesses, and sends a handover completion notification to the target MSC Server.
  • the target MSC Server sends a handover completion notification to the IWG.
  • the IWG sends a handover completion notification to the source radio access network, and a confirmation process.
  • the interruption time of the downlink media stream is basically receiving the media update from step 411 UE-B.
  • the request begins to send a downstream media stream to the MGW, to step 419, the interrupt time is the execution and transmission time of steps 412, 413, 414, 417, 418, and the sum of the wireless switching execution of step 419, ie T412 + T413 + T414 + T417 + T418 + T419.
  • the uplink media stream is always performed by the source bearer-IMS bearer before UE-A performs step 419, but is interrupted during step 419, so the uplink media stream has an interrupt time of T419.
  • the time of T412 + T413 + T414 + T417 + T418 is about 200ms, and the time of T419 is about 100ms, then the downlink media stream interruption time is about 300ms.
  • the interrupt time of the upstream media stream is about 100ms.
  • the interruption time caused by network switching will increase, even more than 300ms.
  • step 418 the user is notified to switch.
  • the whole step and the link are relatively large, especially when the media update of the remote user is involved, and in a special case, the time is longer.
  • the user moves at a high speed, or there is a sudden decay of the wireless signal
  • the technical problem to be solved by the present invention is to provide a method and system for implementing voice switching in a single radio access mode to ensure successful handover of voice services.
  • the present invention provides a method for implementing voice service switching in a single radio access mode, the method comprising: when the source radio access network determines to switch the ongoing voice service of the single radio access terminal to the target circuit Domain network,
  • the IWG and the target circuit domain network complete a circuit domain handover preparation process
  • the wireless access terminal While accessing the branch handover, the IWG, to the single through the source wireless access network
  • the wireless access terminal sends pre-handover indication information and handover information
  • the single radio access terminal waits for a handover command according to the pre-handover indication information, and completes a subsequent handover procedure.
  • the step of the IWG transmitting the pre-handover indication information and the handover information to the single radio access terminal by using the source radio access network includes: sending, by the IWG, a pre-handover response to the source radio access network a message, where the pre-handover indication information and the handover information are carried; the source radio access network sends a pre-handover notification message to the single radio access terminal, where the pre-handover indication information and the handover information are carried .
  • the method further includes, after the step of completing the circuit domain switching preparation process, the IWG establishing a circuit connection with the target circuit domain network;
  • the step of the IWG transmitting a pre-handover response message to the source radio access network is performed in parallel with the step of establishing, by the IWG, the circuit connection with the target circuit domain network, or establishing the target circuit domain network in the IWG The steps of the circuit connection are performed afterwards.
  • the single radio access terminal waits for the handover command according to the pre-handover indication information, and the step of completing the subsequent handover process includes: the single radio access terminal saves the handover information according to the pre-handover indication information, and starts the handover at the same time.
  • the command waits for a timer; the duration of the switch command waiting timer is greater than the maximum time for the IMS session switch to complete the update under normal conditions;
  • the single wireless access terminal When the single wireless access terminal receives the handover command, or the wireless currently being used cannot meet the communication requirement, or the handover command waits for the timer to overflow, performs a wireless handover operation according to the handover information, and cuts into the target. a circuit domain network, and resetting the handover waiting command timer; or when the handover command waits for the timer to overflow, if the handover command is not received and the wireless access can continue to be used, the single wireless access terminal exits the wait for the handover command The status continues to use the source wireless access network.
  • the method further includes the step of remote branch media update, where the service continuity application server SCC AS does not carry the media resource information provided by the session handover requester when sending the media update request to the remote end of the session; the SCC AS The media resource information is carried when the acknowledgment message is sent to the remote end of the session; the remote end of the session changes the sending direction of the media stream according to the received media resource information.
  • the present invention also provides a voice service cut in a single wireless access mode.
  • the system includes a source wireless access network, a target circuit domain network, an interworking gateway, and a single wireless access terminal, where
  • the source radio access network is configured to send a circuit domain handover request to the interworking gateway IWG, and is further configured to receive pre-handover indication information and handover information sent by the IWG, and forward the received pre-handover to the single radio access terminal. Indication information and switching information;
  • the target circuit domain network is configured to complete a circuit domain handover preparation process with the IWG; the IWG is configured to complete a circuit domain handover preparation process with the target circuit domain network; and simultaneously access the branch handover to the source wireless
  • the access network sends the pre-handover indication information and the handover information.
  • the single radio access terminal is configured to: receive the pre-handover indication information and the handover information sent by the source radio access network, and wait for the handover command according to the pre-handover indication information, and complete Subsequent switching process.
  • the single radio access terminal is configured to save the handover information according to the pre-handover indication information, and simultaneously initiate a handover command waiting timer; when the single radio access terminal receives a handover command, or is currently in use
  • the wireless cannot perform the wireless switching operation according to the switching information when the communication request is met, or the switching command waits for the timer to overflow, cut into the target circuit domain network, and reset the switching waiting command timer, or wait for the switching command.
  • the timer overflows, the handover command is not received, and the radio access can continue to be used.
  • the state of waiting for the handover command is exited, and the source radio access network is continued to be used.
  • the duration of the handover command waiting timer is greater than the normal IMS session handover. The maximum time for the update.
  • the IWG is configured to: send a pre-handover response message to the source radio access network, where the pre-handover indication information and the handover information are carried; the source radio access network is set to: The wireless access terminal sends a pre-handover notification message, where the pre-handover indication information and the handover information are carried.
  • the IWG is also arranged to establish a circuit connection to the target circuit domain network.
  • the system also includes a service continuity application server SCC AS and a session remote end.
  • the SCC AS is configured to: send a media update request to the remote end of the session, where the media update request does not carry the media resource information provided by the session switching requester; and send an acknowledgement message to the remote end of the session, where the acknowledgement message is carried The media resource information;
  • the session remote end is configured to: receive the media update request and the confirmation message, and according to The media resource information changes a media stream sending direction.
  • the present invention further provides a method for implementing voice service switching in a single radio access mode, the method comprising: when a source radio access network decides to switch an ongoing voice service to a target circuit domain network, When the remote media is updated,
  • the service continuity application server SCC AS sends a media update request to the remote end of the IMS session, where the media resource information provided by the session handover requester is not carried;
  • the remote end of the IMS session After receiving the acknowledgement message, the remote end of the IMS session changes the media stream sending direction according to the media resource information provided by the session requester.
  • the SCC AS After receiving the session switching request, the SCC AS sends the media update request to the remote end of the IMS session, where the session switching request carries the media resource information provided by the session switching requester; and the SCC AS sends the IMS to the IMS.
  • the SCC AS In the step of sending a confirmation message to the remote end of the session, the SCC AS is in the message.
  • the present invention further provides another implementation system for voice service switching in a single radio access mode, where the system includes a service continuity application server SCC AS and a session remote end, where
  • the SCC AS is configured to: send a media update request to the remote end of the session, where the media resource information provided by the session switch requester is not carried, and send an acknowledgement message to the remote end of the session, where the media resource information is carried;
  • the remote end is configured to receive the media update request and the acknowledgement message, and change a media stream sending direction according to the media resource information.
  • the SCC AS is further configured to: receive a session switching request, and receive a media update response returned by the remote end of the session; the remote end of the session is further configured to: return a media update response to the SCC AS.
  • the method and system of the present invention send pre-handover indication information and handover information to the UE while accessing the branch handover.
  • the UE can also perform handover according to the handover information carried in the pre-handover request even if the handover command caused by the long-term handover process cannot be notified to the UE.
  • the remote media handover process is performed.
  • the present invention optimizes the media negotiation process with the remote UE by using the control function of the SCC AS to change the time when the media resource information reaches the remote end of the session, thereby reducing the downlink media stream switching interruption time.
  • FIG. 1 is a schematic diagram of a service scenario of voice switching in a single radio access mode.
  • FIG. 2 is a schematic structural diagram of voice switching in a single wireless access mode.
  • FIG. 3 is a flow chart of voice service switching in a single radio access mode in the prior art.
  • FIG. 4 is a flow chart of another voice service handover in a single radio access mode in the prior art.
  • FIG. 5 is a schematic diagram of a signaling flow of a first embodiment of a single radio access voice switching method according to the present invention.
  • 6 is a schematic diagram of a signaling flow of a second embodiment of a single radio access voice switching method according to the present invention.
  • FIG. 7 is a schematic diagram of a signaling flow of a third embodiment of a single radio access voice switching method according to the present invention.
  • FIG. 8 is a schematic flowchart of a method for implementing voice service switching in a single radio access mode according to the present invention.
  • the present invention provides a method for implementing voice service switching in a single radio access mode, which is applied to a voice switching service in a single radio access mode, in a remote media, in order to solve the problem of the handover failure caused by the long switching time of the media stream.
  • the handover process by using the control function of the SCC AS, the time for the media resource information to reach the remote end of the session is changed, and the media negotiation process with the remote UE is optimized, thereby reducing the downlink media stream switching interruption time.
  • the single radio access UE accesses the source radio access network, and establishes an IMS session with the remote device through the IMS, and the session path is anchored in the SCC AS, and the source radio access network decides to switch the ongoing voice service to the target.
  • the implementation manner of the single wireless access mode voice service switching includes:
  • the SCC AS After receiving the session switching request of the session switching requester, the SCC AS sends the session switching request to the IMS.
  • the remote end sends a media update request, where the media resource information provided by the session switching requester in the session switching request is not carried;
  • the SCC AS receives the media update response from the remote end of the IMS session, and then sends the media update request to the remote end of the IMS session. Sending a confirmation message, where the media resource provided by the session switching requester is carried;
  • the remote end of the IMS session After receiving the acknowledgement message, the remote end of the IMS session changes the media stream sending direction according to the media resource information provided by the session requester.
  • FIG. 5 is a flowchart of a single radio access voice handover according to a first embodiment of the present invention, illustrating that UE-A accesses in a source radio access coverage area, establishes an IMS session with a remote UE-B, and then switches to a CS network. the process of.
  • This embodiment is independent of the non-speech media and only considers the handover process from the source radio access network to the target CS network. The steps are described as follows:
  • Steps 501 to 508 are the same as steps 401 to 408 in Fig. 4.
  • the IWG uses the handover identifier STN as the called number, and sends an handover request to the IMS by using an Initial Address Message (IMM) message, requesting the SCC AS to perform a handover process;
  • IMM Initial Address Message
  • This step can be performed after step 507 and executed in parallel with step 508.
  • the MGCF converts the IAM into a SIP Invite message (INVITE), and sends the information to the SCC AS through the network element such as the CSCF, and carries the media resource information provided by the MGW.
  • the MGW starts the local media receiving port indicated in the media resource information, and prepares to receive the media stream sent by the peer end;
  • the SCC AS sends a SIP media update request (RE-INVITE) to the remote UE-B, and does not carry the media resource information, that is, the empty SDP packet.
  • RE-INVITE SIP media update request
  • the UE-B returns a SIP acknowledgment response, and carries the media resource information provided by the UE-B.
  • the acknowledgment response may be a final acknowledgment response (200 OK), or may be a temporary response, such as If it is a temporary response, it will go through a similar media negotiation process.
  • Embodiments herein are described in terms of a final confirmation response.
  • the SCC AS selects the coding format and the priority order jointly supported by the two parties according to the coding information in the media information of the MGW obtained in step 510 and the coding information in the media information of the UE-B obtained in this step.
  • the UE-B starts the local media receiving port indicated in the media resource information, and prepares to receive the media stream sent by the peer end; the local media receiving port may use the media receiving port that is originally used, or may allocate a new media receiving port; If a new media receiving port is used, the two ports are simultaneously received. When the media received by the new port is closed, the original media receiving port is closed, so that the media is not lost during the port changing process. Since the UE-A is still in the source radio access network at this time, the UE-B can continue to receive the media stream sent by the UE-A, that is, the answering is not affected.
  • the UE-B since the media resource information is not carried in the step 511, the UE-B does not receive the media resource information of the peer end, and does not change the sending direction of the original media stream, that is, the media is still sent to the UE-A through the source bearer-IMS bearer. Therefore, compared with the prior art, the downlink media still performs normally; 513.
  • the SCC AS forwards the 200 OK to the MGCF, and carries the media resource information provided by the UE-B.
  • the encoding format and the sequence in the media information are selected by using the SCC AS in step 512. the result of.
  • the MGCF controls the MGW to start transmitting media to the media receiving port of the UE-B.
  • the uplink media stream is not interrupted.
  • the MGW does not receive the media stream of the UE-A, and does not send the media stream to the UE-B.
  • UE-B does not close the receiving port of the source bearer.
  • the MGCF sends a response message (Answer Message, referred to as ANM) response to the IWG.
  • ANM Answer Message
  • the MGCF returns a SIP acknowledgement request (ACK) to the SCC AS at the same time;
  • the SCC AS sends an ACK acknowledgement message to the UE-B, and carries the media resource information provided by the MGW acquired in step 510.
  • the encoding format and order in the media information are the results selected by the SCC AS in step 512.
  • This step 516 can be performed when step 513 is performed.
  • the UE-B will change the sending direction of the media stream, and send the media to the receiving port specified in step 516, that is, the media receiving port of the MGW, and stop the media receiving port from the source bearer path - the IMS bearer to the UE-A.
  • the UE-A will not be able to receive the media stream sent by the UE-B, and the user A cannot hear the voice of the user B.
  • steps 508 and 516 the handover process of the IMS session and the media update of the remote UE are completed, and the target media bearer between the target radio subsystem-target MSC Server-MGCF/MGW-UE-B is established.
  • the media stream of B is normal (referred to as an uplink media stream), and the media stream terminal of UE-B to UE-A (referred to as a downlink media stream) is interrupted from step 516 and appears as a single pass.
  • Steps 517 - 519 are the same as steps 417 ⁇ 419 in Figure 4, at this time UE-A switches to the target CS wireless network, and establishes the target bearer seen by UE-A and the target wireless subsystem: CS bearer 1 to complete the access side handover , establish a media connection with the remote UE-B, and the call resumes normal. At this time, UE-B receives the media stream from the receiving port carried by the target. If the receiving port of the source bearer is different from the receiving port of the target bearer, UE-B will close the receiving port of the source bearer.
  • Steps 520 ⁇ 523 are the same as steps 420 ⁇ 423 in Figure 4.
  • the interruption time of the downlink media stream is basically from the step 516 when the UE-B receives the media update request and starts to send the downlink media stream to the MGW, until the completion of step 519.
  • the step 516 is performed after the step 515, and the processing and transmission time of the steps 515, 516 are exactly equal to the times of the steps 514, 517, 518, the interrupt time is T519, if the two are different, the interrupt time is T519 plus The absolute value of the difference between the two.
  • the uplink media stream is always performed by the source bearer - IMS bearer before UE-A performs step 519, but is interrupted during step 519, so the uplink media stream has an interrupt time of T519.
  • T519 is about 100ms, so the interruption time of the upstream media stream is about 100ms, and the interruption time of the downlink media stream is 100ms, and the maximum value is also far less than 100ms. current technology. It can be seen that by using the control function of the SCC AS, the time for the media resource information to reach the remote end of the session is changed, and the media negotiation process with the remote UE is optimized, thereby reducing the downlink media stream switching interruption time.
  • the present invention further provides a system for implementing voice service switching in a single radio access mode, where the system includes an SCC AS and a session remote end, where
  • the SCC AS is configured to send a media update request to the remote end of the session, where the media resource information provided by the session switching requester is not carried, and is further configured to send an acknowledgement message to the remote end of the session, where the media resource information is carried;
  • the session remote end is configured to receive the media update request and the acknowledgement message, and is further configured to change a media stream sending direction according to the media resource information.
  • the implementation system should also include a source radio access network, a target network, an interworking gateway, and a single radio access terminal, and details are not described herein.
  • the present invention also provides another method for implementing voice service switching in a single radio access mode.
  • the main idea of the method is to perform the connection after the circuit domain is ready for handover.
  • the interworking gateway IWG sends the pre-handover indication information and the handover information to the single radio access terminal through the source radio access network, so that the single radio access terminal enters the pre-handover state.
  • the present invention utilizes the pre-handover mechanism, and the IWG notifies the UE to perform handover preparation while performing IMS session handover. After the IMS session handover is completed, the UE is formally notified to perform handover, thereby avoiding The handover process cannot notify the UE of the handover problem, and the handover is guaranteed to be successful.
  • the method includes:
  • Step 801 The source radio access network sends a circuit domain handover request to the interworking gateway IWG.
  • Step 802 The IWG and the target circuit domain network complete a circuit domain handover preparation process.
  • Step 803 Perform an access branch handover.
  • the IWG sends the pre-handover indication information and the handover information to the single radio access terminal by using the source radio access network;
  • the sending, by the IWG, the pre-handover indication information and the handover information to the single radio access terminal by using the source radio access network includes: sending, by the IWG, a pre-handover response message to the source radio access network, where The pre-handover indication information and the handover information are carried by the source radio access network, and the pre-handover notification message and the handover information are sent to the single radio access terminal.
  • the pre-handover response message and the pre-handover notification message are both newly defined messages.
  • the pre-handover indication information and the handover information may be carried by the original message.
  • Step 804 The single radio access terminal saves the handover information, waits for a handover command, and completes a subsequent handover procedure.
  • the single wireless access terminal initiates a handover command waiting timer; when the single wireless access terminal receives the handover command, or the currently used wireless cannot meet the communication requirement, or the handover command waits for the timer to overflow,
  • the switching information performs a wireless switching operation and cuts into the target circuit domain network.
  • the handover command waits for the timer to overflow if the handover command is not received and the wireless access can continue to be used, the UE exits the state of waiting for the handover command and continues to use the source radio access network. This method can prevent the session switching on the network side from being completed and an exception is generated.
  • the handover information in the subsequently received handover command takes precedence.
  • the duration of the handover command waiting timer is greater than the maximum time during which the IMS session handover completes the update, and the single radio access terminal resets the handover waiting command timer when performing the radio handover operation.
  • FIG. 6 is a schematic diagram of a handover process in a single radio access mode according to a second embodiment of the present invention. Description The process of UE-A accessing in the source radio access coverage area, establishing an IMS session with the remote UE-B, and then switching to the CS network, the process includes the following steps:
  • the UE When the UE accesses the IMS from the source wireless network and enters the call state, the UE periodically detects the surrounding wireless environment, and notifies the source wireless access network through the measurement report.
  • the source wireless access network checks the current wireless communication condition according to the local configuration, and if it is found that the currently used wireless access is no longer suitable for communication, for example, if the signal strength is lower than the set threshold, the surrounding area will be reported from the UE.
  • the source radio access network discovers that the communication medium includes voice, sends a CS handover request to the IWG, carries the cell information, the user identifier, and the session transfer number (STN) of the target CS network, and notifies the IWG to perform the handover. ; Step 605;
  • step 604 if the communication medium also contains non-speech PS media, and the target network and the terminal support CS and PS access simultaneously, send a PS handover request to the target PS network; go to step 606;
  • the IWG receives the handover request of the source radio access network, and completes the radio resource preparation by using the existing handover mechanism of the CS.
  • the IWG establishes a CS circuit connection with the target CS network. This step is independent of steps 606, 607 and can be performed simultaneously with steps 606, 607.
  • the IWG returns a CS pre-handover response message to the source radio access network, indicating that the handover preparation is completed, and carries the pre-handover indication information and the handover information.
  • the handover information carried in the message includes attributes of the target CS access network and detailed access information.
  • the message may be a newly defined message, such as a pre-handover response message, or an indication is added to the existing CS handover response indicating that the message is a CS pre-handover response message.
  • the IWG then sends a session switch request to the IMS, and establishes an inbound call branch, instead of the cut-out call branch originally established through the source radio access network, to implement access branch switching and remote media update.
  • the target PS network receives the PS handover request of step 604, and completes the PS handover preparation process. 609. After the step 608 is complete, the target PS network returns a PS handover response to the source radio access network, indicating that the handover preparation is complete, and carrying the handover information.
  • the source radio access network receives the CS pre-handover response message in step 606 and the PS handover response in step 609, and knows that the target network is ready to be completed, but the handover of the voice media is not completed, and then sends a pre-handover notification message to the UE, carrying Detailed switching information, including detailed access information of the target network (including CS network and PS network);
  • the UE receives the pre-handover notification message request, saves the handover information with the target network, starts the handover command waiting timer, and waits for the handover command.
  • the UE does not perform the wireless handover procedure, and when the handover command is received, or the currently used radio access mode cannot meet the communication requirements, such as moving the coverage area of the source radio access network, or switching the command waiting timer If the overflow occurs, the UE performs a wireless handover operation according to the handover information, switches to the target wireless network specified by the handover command, or the target wireless network specified in the pre-switch request, and resets the handover command waiting timer. Alternatively, when the handover command waits for the timer to overflow, if the handover command is not received and the radio access can continue to be used, the UE exits the state of waiting for the handover command and continues to use the source radio access network.
  • the IWG may send a handover cancellation request through the source radio access network, or the source radio access network sends a handover cancellation request to the UE.
  • the UE After receiving the request, the UE resets the handover command waiting timer and exits the waiting for the handover command. status.
  • the UE can complete some preparations for handover in advance according to a specific implementation manner, such as starting of a hardware circuit, loading and initializing a circuit domain software module, and a switching module to speed up the switching speed.
  • the request is treated as an unknown message, and the unknown request is not processed or returned, without affecting the normal handover procedure.
  • the handover information carried in the pre-handover notification message includes attributes of the target access network, and detailed access information, including detailed access information of the target CS access network and/or the target CS access network.
  • the message may be a newly defined message, or an indication may be added to an existing handover command indicating that the message is a pre-handover notification message.
  • the UE waits for a handover command. 612. After the step 607 is completed, the IWG returns a CS handover response to the source radio access network, indicating that the handover preparation and the IMS handover are completed, and carrying the handover information.
  • the source radio access network receives the CS handover response in step 612 and the PS handover response in step 609, and sends a handover command to the UE.
  • the UE performs handover and switches to the target network.
  • FIG. 7 is a flow chart of a single radio access voice handover according to a second embodiment of the present invention, which describes that UE-A accesses in a source radio access coverage area, establishes an IMS session with a remote UE-B, and then switches to a CS network. the process of.
  • the pre-handover mechanism can also be used simultaneously with the method of reducing the downlink media stream switching interruption time mentioned in the first embodiment.
  • the switching process includes the following steps:
  • Steps 701 to 708 are the same as steps 501 to 508 in FIG.
  • the IWG uses the handover identifier STN as the called number, and uses the initial address message (Initial).
  • the address message (IAM) message sends a handover request to the IMS, requesting the SCC AS to perform the handover process;
  • This step can be performed after step 707 and executed in parallel with step 708.
  • the IWG sends a pre-handover command message to the source radio access network, and carries the handover information obtained in step 707;
  • This step number does not indicate the execution order, just for convenience of explanation, so as to establish a comparison relationship with step 717, and steps 417, 517 of Fig. 4 and Fig. 5.
  • the source radio access network sends a pre-handover notification message to the UE-A, indicating that the UE-A network has made a decision to perform handover, and switches the handover information of the target CS radio network.
  • step number does not indicate the order of execution, just for convenience of explanation, and step 718, and FIG. Steps 418, 518 in Figure 5 establish a correspondence.
  • the UE-A receives the pre-handover notification message request, saves the handover information with the target CS wireless network, starts the handover command waiting timer, and waits for the handover command.
  • Steps 710 ⁇ 716 are the same as steps 510 ⁇ 516 in FIG. 5, complete the IMS session handover process, and the media update of the remote UE, and establish a slave radio subsystem - target MSC Server - MGCF / MGW - UE-B
  • the target media bearer and the interruption of the media stream are the same as in FIG. 5.
  • Steps 717 to 719 are the same as steps 517 to 519 in FIG. 5, and the IWG performs the IMS session handover.
  • the source radio access network sends a handover request, and the UE-A switches to the target CS radio network to establish the UE- Target bearer between A and the target radio subsystem: CS bearer 1 completes the IMS session handover, establishes the media connection with the remote UE-B, and the call resumes normal.
  • step 718 If the handover command to step 718 cannot be sent to UE-A because the user has moved out of the source radio access network, and the source radio access network sends a pre-handover notification to UE-A, the source radio network considers UE-A The source wireless access network has been cut out.
  • Step 712 arrives at the IWG earlier than step 714
  • the IWG may continue to perform step 717 to send a handover command after step 714, or skip step 717, directly Step 721 is executed to notify the source radio access network that the handover has been completed.
  • the present invention further provides a system for implementing voice service switching in a single radio access mode, where the system includes a source radio access network, a target network, Interworking gateway, single wireless access terminal SCC AS and session remote, wherein
  • the source radio access network is configured to send a circuit domain handover request to the interworking gateway IWG, and further configured to receive circuit domain handover indication information and handover information sent by the IWG, and forward the received information to the single radio access terminal.
  • Pre-switching indication information and switching information Pre-switching indication information and switching information
  • the source radio access network sends the pre-handover indication information and the handover information to the single radio access terminal by using a pre-handover notification message.
  • the target network is configured to complete a circuit domain handover preparation process with the IWG; and send pre-handover indication information and handover information to the source radio access network while performing access branch handover;
  • the single radio access terminal is configured to receive circuit domain handover indication information and handover information sent by the source radio access network, and is further configured to save the handover information, and wait for a handover command according to the pre-handover indication information to complete subsequent handover. process.
  • the single wireless access terminal is further configured to start a handover command waiting timer at the same time; when the single wireless access terminal receives the handover command, or the currently used wireless cannot meet the communication requirement, or the handover command waits for the timer to overflow.
  • the single radio access terminal is further configured to perform a radio handover operation according to the handover information, and cut into the target circuit domain network. Alternatively, when the handover command waits for the timer to overflow, if the handover command is not received and the radio access can continue to be used, the UE exits the state of waiting for the handover command, and continues to use the source radio access network.
  • the SCC AS is configured to send a media update request to the remote end of the session, where the SCC AS does not carry the media resource information provided by the session switching requester, and is further configured to send an acknowledgement message to the remote end of the session, where Carrying the media resource information;
  • the session switching requester referred to herein refers to the media gateway MGW.
  • the session remote end is configured to change a media stream sending direction according to the received media resource information.
  • the method and system of the present invention send pre-handover indication information and handover information to the UE while accessing the branch handover.
  • the UE can also perform the handover according to the handover information carried in the pre-handover request even if the handover command caused by the long-term wired handover process cannot be notified to the UE. Therefore, in the case that the IMS session switching process is relatively long, normal switching can be performed, and the interruption time is optimized.
  • Industrial Applicability The method and system of the present invention transmits pre-handover indication information and handover information to the UE while access branch handover is completed after the target circuit domain network handover preparation is completed.
  • the UE can also perform the handover according to the handover information carried in the pre-handover request even if the handover command caused by the long-term wired handover process cannot be notified to the UE.
  • the present invention optimizes the media negotiation process with the remote UE by using the control function of the SCC AS to change the time when the media resource information reaches the remote end of the session, thereby reducing the downlink media stream. Switch the interruption time.

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

本发明提供一种单无线接入方式下语音业务切换的实现方法，当源无线接入网络决定将单无线接入终端正在进行的语音业务切换到目标电路域网络时，该方法包括：所述源无线接入网络向互通网关IWG发送电路域切换请求；所述IWG与所述目标电路域网络完成电路域切换准备过程；在接入分支切换的同时，所述IWG，通过所述源无线接入网络向所述单无线接入终端发送预切换指示信息及切换信息；所述单无线接入终端保存所述切换信息，根据所述预切换指示信息等待切换命令，完成后续切换过程。本发明实现方法及系统，可以保证实现语音业务成功切换。

Description

单无线接入方式语音切换的实现方法
及系统
技术领域
本发明涉及通信领域， 尤其涉及一种单无线接入方式下语音切换的实现 方法及系统。
背景技术
在第二代（2 Generation, 简称 2G ) 、 第三代（ 3 Generation, 简称 3G ) 移动通讯网络中， 如全球移动通讯系统 （ Global System for Mobile communications , 简称为 GSM ) 、 通用移动通讯系统 ( Universal Mobile Telecommunications System, 简称为 UMTS ) , 釆用电路交换（ Circuit Switch, 简称 CS )方式提供语音业务， 并形成了良好的覆盖。 随着无线宽带技术的发 展， 以及网络互联协议（Internet Protocol, 简称 IP )技术的发展， 整个网络 向全 IP 的方向演进， 一方面通讯网络的核心网向 IP 多媒体子系统 （IP Multimedia Core Network Subsystem , 简称 IMS )演进， 另一方面无线接入网 络向分组交换发展， 通过分组交换（Packet Switch, 简称 PS ) 网络承载语音 以及其他业务， 并能够直接接入 IMS, 由 IMS提供包括语音业务在内通讯业 务。
IMS是由第三代合作伙伴计划 （ 3rd Generation Partnership Project, 简称 3GPP )提出的一种基于 IP的网络架构，构建了一个的开放而灵活的业务环境， 与接入无关， 可以支持多媒体应用， 能够为用户提供丰富的多媒体业务。
无线接入方式的发展方向有多种， 比如 3GPP提出了长期演进 /系统架构 演进 ( Long Term Evolution/ System Architecture Evolution, 简称 LTE/SAE )的 下一代网络架构， 釆用分组交换技术， 能提供更高的传输速率、 更短的传输 延时， 可以承载语音业务在内的实时业务， 其可以作为 IMS网络的一种接入 方式， 由 IMS提供业务。
又如家庭基站（ Home NodeB , 简称 ΗΝΒ )系统， 是由 3GPP提出的一种 微蜂窝接入方式 , 包括 ΗΝΒ接入节点以及 ΗΝΒ网关。 将 ΗΝΒ接入节点其 部署在楼宇等宏蜂窝信号难以到达的地方实现信号覆盖， 或话务量比较大的 地区， 分担用户发生在室内或特定区域的话务量。 HNB系统通过 CS用户接 口与 UE相连， 再接入现有的 CS核心网， 实现语音业务， 也可以引入互通功 能， 直接出 IP接口， 将语音业务直接接入 IMS, 由 IMS提供业务。
在这些接入方式中， 有的接入技术的部署是个渐进的过程， 比如运营商 在部署 LTE/SAE过程中， 初期可能只在热点地区进行覆盖； 有些接入方式 适用于局部部署， 比如 HNB系统， 其覆盖范围只局限家庭、 楼宇等小范围。 由于本文重点描述用户从这些局部覆盖区接入，并发生语音业务情况下的语 音业务连续性， 故称这些局部覆盖区为源无线接入覆盖区。
图 1是在上述场景下的语音切换（又称语音连续性） 的业务场景。 用户 在源无线接入覆盖区进行语音业务时， 直接接入 IMS, 与远端用户建立 IMS 会话。 当用户移出上述覆盖区域时， 为了保证语音业务的连续性， 切换到 CS网络， 并利用 IMS中的会话锚定功能保持与远端用户通话的连续性， 这 样可以充分利用 CS网络覆盖好的优势， 保证业务的连续性。
在上述场景中， 用户的移动设备在通话状态下， 同时只能接入一种无线 网络， 比如对于 LTE/SAE用户设备， 在切换前， 只能接入 LTE/SAE网络， 而不能同时接入 CS网络； 当移动到 CS网络覆盖区， 必须断开与 LTE/SAE 的无线连接，才能接入 CS网络，本文中称这种接入方式为单无线接入方式。 对于接入 IMS的 HNB系统， 虽然其切换前以及切换后的无线接入方式都为 CS方式， 单由于接入的核心网不同， 在此也统一称为单无线接入方式。
图 2是单无线接入方式下语音切换的架构示意图。
在 IMS业务体系中， 控制层和业务层分离， 控制层不提供具体业务， 只 向业务层提供必要的触发、 路由、 计费等功能。 控制层中业务触发和控制功 能是呼叫会话控制功能 205 ( Call Session Control Function, 简称 CSCF ) 完 成的， 业务层是由一系列应用服务器（Application Server, 简称 AS )组成。 控制层根据用户的签约信息控制业务触发， 调用 AS上的业务， 实现业务功 能。
为了实现 IMS会话的切换业务， 或称为业务连续性业务， 在 IMS中引入 业务连续性 AS 206 ( Service Continuity Control AS, 简称 SCC AS )负责锚定 会话的信令路径， 因此称之为信令路径的锚定点。 当发生切换时， 虽然 UE 到 SCC AS 206的信令路径发生了变化， 但 SCC AS到远端的信令路径仍保 持不变， 从而使远端不感知切换的发生。
为了与传统的电路域网络互通， 在 IMS 边缘建设媒体网关控制功能 ( Media Gateway Control Function,简称 MGCF )和媒体网关（ Media Gateway, 简称 MGW ) 207 , MGCF完成 CS信令和 IMS信令之间的互通和转换， 并 控制 MGW完成 CS承载和 IMS承载之间的转换。
互通网关（ Interworking Gateway, 简称 IWG ) 204是为了支持单无线接 入， 基本上在移动交换中心 （Mobile Switching Center, 简称 MSC ) Server 功能的基础上， 增加切换支持功能， 并通过 MSC Server之间的接口与目标 CS网络 203相连， 通过 MGCF/MGW 207与 IMS互通， 同时通过接口与源 无线接入网络 202连接， 接收源无线接入网络的切换请求， 完成切换工作。
IWG 204可以进一步增强， 包含 MGCF和 MGW的功能， 直接出 SIP接 口接入 IMS, 此时不需要经过 MGCF/MGW。
用户设备 201通过 Uu接口接入源无线接入网络 202, 并通过 SGi口接 入 IMS 网络， 在上述接口上承载着控制信令以及媒体流。 控制信令釆用会 话初始协议（ Session Initial Protocol, 简称 SIP协议 ) , 其路径如图 2虚线所 示。 UE 201和远端 UE 208的 SIP会话路径经过 S-CSCF 205触发到 SCC AS 206, 并在 SCC AS 206锚定， 由 IMS提供会话控制以及业务。 在上述控制 路径的控制下， 在 UE 201和远端 UE 208之间建立媒体路径。
如果针对 HNB接入方式， Uu接口上为 CS接入信令和媒体， 源无线接 入网络（HNB系统 )将 CS接入信令和媒体转换成 IMS信令和媒体， 再接 入 IMS。
图 3是现有技术中单无线接入方式下的切换过程示意图。
301、 当 UE从源无线网络接入 IMS , 并进入通话态时， UE定时检测周 围的无线环境， 通过测量报告通知源无线接入网路；
302、 源无线接入网络根据本地的配置检查当前的无线通讯条件， 如果发 现当前所使用的无线接入不再适合进行通讯， 比如信号强度低于设定的阔 值， 将从 UE上报的周围无线网络的信息选择切换的目标网络； 303、 源无线接入网络发现通讯媒体中含有语音， 向 IWG发送 CS切换 请求， 携带目标 CS网络的小区信息、 用户标识以及会话转移号码（Session Transfer Number, 简称 STN )等信息，通知 IWG进行切换，转执行步骤 305;
304、 与步骤 303同时， 如果通讯媒体中还含有非语音的 PS媒体， 且目 标网络和终端同时支持 CS和 PS接入，则向目标 PS网络发送 PS切换请求， 转执行步骤 306;
305、 IWG收到源无线接入网络的切换请求， 利用 CS现有的切换机制， 完成无线资源准备和电路连接的过程， 然后通过 MGCF/MGW向 IMS发送 会话切换请求， 建立切入呼叫分支， 代替原来通过源无线接入网络建立的切 出呼叫分支， 实现接入分支切换， 并更新与远端的媒体连接；
306、 目标 PS网络接收到 PS切换请求， 完成 PS切换准备过程；
307、 当步骤 305完成后， IWG向源无线接入网路返回 CS切换响应， 表 示切换准备完成， 并携带切换信息；
308、 当步骤 306完成后， 目标 PS网络向源无线接入网络返回 PS切换响 应， 表示切换准备完成， 并携带切换信息；
309、 源无线接入网络接收步骤 307中 CS切换响应和步骤 308中的 PS 切换响应， 知道目标网络准备完成， 则向 UE发送切换命令。
310、 UE执行切换， 切换到目标网络。
由于本发文重点描述语音切换， 即到目标 CS 网络的切换， 因此不对非 语音的 PS的媒体的切换过程中进行描述。
完成上述 IMS会话切入过程后， 通过源无线接入网络向 UE发送切换命 令， 指示 UE切换到目标 CS网络， 完成接入侧切换过程， 保证会话不中断。
在上述切换过程中， 会有短暂的语音中断， 为了保证用户的体验， 要求 语音中断时间不大于 300ms。
图 4是现有技术中单无线接入方式下的切换流程图。
UE-A在源无线接入覆盖区接入，通过源无线接入网络接入 IMS,与远端 UE-B建立 IMS会话，该会话的信令路径以 SCC AS为锚点，媒体路径从 UE-A 经过源无线接入网络和 UE-B连接。 源接入的信令路径包括两端： UE到 SCC AS的源信令接入路径（又称为切出接入分支）和远端信令接入分支， 原媒体 路径为 IMS承载。本流程只描述有语音的场景，其切换过程的步骤描述如下：
401、在通话过程， UE-A周期性的向源无线接入网络上报无线测量报告， 该报告中包括当前正在使用的无线接入方式的测量数据， 以及周围无线接入 方式的测量数据；
402、 源无线接入网络在根据上报的无线测量报告， 进行切换决策。 当 UE-A正在使用的无线接入方式的无线条件变差， 比如 UE-A接收到信号强度 低于设定的切换阔值， 而且 CS接入更适合通讯时， 决定将承载切换到 CS网 络。
403、 源无线接入网络向 IWG发送 CS切换请求， 携带用户标识、 目标
CS网络的小区信息、 以及切换路由信息 （如 STN、 SCC AS的标识）等；
404、 IWG确定目标 CS小区所在的目标 MSC Server,向目标 MSC Server 发送切换准备请求；
405、 目标 MSC Server 向目标无线子系统（RNS/BSS, Radio Network Subsystem/Base Station Subsystem, 无线网络子系统 /基站子系统）转发切换准 备请求；
406、 目标无线子系统根据切换准备请求的指示， 预留无线资源， 并向目 标 MSC Server返回切换准备响应， 携带目标无线接入网络的详细信息；
在该步骤完成时 ,建立目标 MSC Server与目标无线子系统之间的目标承 载 - CS承载 2。
407、 目标 MSC Server发送切换准备响应给 IWG;
通过步骤 403 ~ 407标准的 CS切换准备过程， 完成切换的准备过程。
408、 IWG建立与目标 MSC Server之间的电路连接；
该步骤完成后，建立 IWG和目标 MSC Server之间目标承载 - CS承载 3。 409、 IWG使用切换标识 STN作为被叫号码， 使用初始地址消息（Initial
Address Message, 简称 IAM )消息向 IMS发送切换请求， 请求 SCC AS执行 切换过程； 该步骤可以在步骤 407后执行， 与步骤 408并行执行。
410、 MGCF将 IAM转换成 SIP邀请消息 （ INVITE ) 消息， 经过 CSCF 等网元发送给 SCC AS , 并携带釆用会话描述协议 （Session Description Protocol, 简称 SDP )描述的 MGW提供的媒体资源信息；
此时 MGW启动媒体资源信息中指示的本地媒体接收端口， 准备接收对 端发送的媒体流；
411、 SCC AS向远端 UE-B发送 SIP媒体更新请求（RE-INVITE ) , 携 带从步骤 410中获取的 MGW提供的媒体资源信息；
412、 UE-B返回 SIP确认响应， 并携带 UE-B应答的媒体资源信息； 其中确认响应可以是最终确认响应 （200 OK ) , 也可以是临时响应， 如 果是临时响应， 后续还要经过类似的媒体协商过程。
此时 UE-B启动媒体资源信息中指示的本地媒体接收端口， 准备接收对 端发送的媒体流；本地媒体接收端口可以釆用原来正在使用的媒体接收端口， 也可以分配新的媒体接收端口； 如果使用新的媒体接收端口， 则在两个端口 同时接收， 当在新的端口接收的媒体后， 才关闭原来的媒体接收端口， 这样 保证在改变端口过程中， 不丟失媒体。 此时， 由于 UE-A还在源无线接入网 络， 因此 UE-B可以继续收到 UE-A发送的媒体流， 即接听不受影响。
另外， UE将改变媒体流的发送方向， 向步骤 411中指定的接收端口， 即 MGW的媒体接收端口发送媒体，停止向 UE-A的媒体接收端口发送媒体，此 时 UE-A将无法接收到 UE-B发送的媒体流， 表现为用户 A无法听到用户 B 的声音。
413、 SCC AS转发 200 OK到 MGCF, 携带 UE-B应答的媒体资源信息； 该步骤完成后， MGCF/MGW和 UE-B建立目标承载的 IMS承载端。 此 时虽然 MGW向 UE-B发送媒体流的路径已经建立好，但由于 UE-A还没有切 换过来， 实际并没有媒体流。
414、 MGCF向 IWG发送应答消息（ Answer Message, 简称 ANM )响应； 当步骤 408和 414完成后， 完成 IMS会话切换过程， 以及远端 UE的媒 体更新， 建立了从目标无线子系统-目标 MSC Server - MGCF/MGW - UE-B 之间的目标媒体承载。
由于此时 UE-A还没有进行切换， 还在原来的承载发送和接收媒体， 而 UE-B的发送媒体已经切换到目标承载，但仍然可以在原端口接收媒体， 因此 从步骤 412开始从 UE-A到 UE-B的媒体流正常（称为上行媒体流 ) , UE-B 到 UE-A的媒体流中断（称为下行媒体流） ， 表现为单通。
415、 MGCF同时向 SCC AS返回 SIP确认请求（ACK ) ；
416、 SCC AS向 UE-B发送 ACK确认消息；
417、 IWG向源无线接入网络发送 CS切换响应， 携带在步骤 407中获取 的目标 CS接入的详细无线信息；
418、 源无线接入网络向 UE-A发送切换命令， 指示 UE-A切换到指定的 目标 CS网络中；
419、 UE-A执行无线切换过程， 切入到指定的目标 CS网络， 建立与目 标无线子系统的信令以及媒体连接；
此时 UE-A切换到目标 CS无线网络，建立 UE-A和目标无线子系统间的 目标承载： CS承载 1 , 从而完成接入侧切换， 和远端 UE-B建立媒体连接， 通话恢复正常。 此时 UE-B从目标承载的接收端口接收到媒体流， 如果源承 载的接收端口与目标承载的接收端口不同， UE-B将关闭源承载的接收端口。
420、 目标无线子系统检测到 UE成功接入， 向目标 MSC Server发送切 换完成通知；
421、 目标 MSC Server向 IWG发送切换完成通知；
422、 IWG向源无线接入网络发送切换完成通知， 以及确认过程；
423、 SCC AS在上述切换过程完成后， 释放源接入分支。
由上面的流程以及分析可以看出， 在切换过程中存在语音中断时间， 且 上行媒体流和下行媒体流的中断时间不同： 下行媒体流的中断时间基本是从步骤 411 UE-B接收到媒体更新请求开 始向 MGW发送下行媒体流起，到步骤 419完成， 中断时间为步骤 412、 413、 414、 417、 418执行和传输时间， 以及步骤 419无线切换执行的总和， 即 T412 + T413 + T414 + T417 + T418 + T419。
上行的媒体流在 UE-A执行步骤 419之前， 一直通过源承载 - IMS承载 进行， 只是在步骤 419期间会中断， 因此上行媒体流的中断时间为 T419。
根据 UE-A和 UE-B是同一网络的情况下， 根据实验室测试数据， T412 + T413 + T414 + T417 + T418时间约为 200ms, T419约为 100ms, 则下行媒 体流中断时间约为 300ms, 上行媒体流的中断时间约为 100ms。 但在以下的 一些情况发生时， 会导致网络切换引起的中断时间增长， 甚至超过 300ms。
1 ) 当用户在漫游状态， 或呼叫其他网路用户， 或拨打国际长途时， 导致 呼叫环节增多；
2 ) 网络系统比较忙时， 处理能力下降；
3 ) 当 UE-B的处理能力比较差， 或无线接入条件不好， 或带宽限制；
4 ) 当 UE-B和网络之间釆用多次媒体协商处理时。
另外整个切换过程比较长， 从步骤 402决定切换， 到步骤 418通知用户 切换， 整个步骤、 环节比较多， 尤其是涉及远端用户媒体更新时， 在特殊情 况下， 会导致时间更长。 在用户高速移动， 或存在无线信号突然衰减的情况 下， 会出现当执行步骤 418通知用户时， 用户可能已经移出源无线接入覆盖 区的情况， 导致无法通知用户切换， 发生切换失败。 发明内容
本发明要解决的技术问题是提供一种单无线接入方式下语音切换的实现 方法及系统， 以保证语音业务成功切换。
为解决以上技术问题， 本发明提供一种单无线接入方式下语音业务切换 的实现方法， 该方法包括： 当源无线接入网络决定将单无线接入终端正在进 行的语音业务切换到目标电路域网络时，
所述源无线接入网络向互通网关 IWG发送电路域切换请求；
所述 IWG与所述目标电路域网络完成电路域切换准备过程；
在接入分支切换的同时， 所述 IWG, 通过所述源无线接入网络向所述单 无线接入终端发送预切换指示信息及切换信息； 以及
所述单无线接入终端根据所述预切换指示信息等待切换命令， 完成后续 切换过程。
所述 IWG通过所述源无线接入网络向所述单无线接入终端发送所述预 切换指示信息及所述切换信息的步骤包括：所述 IWG向所述源无线接入网络 发送预切换响应消息， 其中携带所述预切换指示信息及所述切换信息； 所述 源无线接入网络向所述单无线接入终端发送预切换通知消息， 其中携带所述 预切换指示信息及所述切换信息。
所述方法在所述完成电路域切换准备过程的步骤之后还包括， IWG建立 与目标电路域网络的电路连接；
所述 IWG 向所述源无线接入网络发送预切换响应消息的步骤是与所述 IWG建立与目标电路域网络的电路连接的步骤并行执行的，或是在所述 IWG 建立与目标电路域网络的电路连接的步骤之后执行的。
所述单无线接入终端根据所述预切换指示信息等待切换命令， 完成后续 切换过程的步骤包括： 所述单无线接入终端根据所述预切换指示信息， 保存 所述切换信息， 同时启动切换命令等待定时器； 所述切换命令等待定时器的 时长大于正常情况下 IMS会话切换完成更新的最大时间；
当所述单无线接入终端接收到切换命令， 或当前正在使用的无线无法在满足 通讯要求， 或切换命令等待定时器溢出时， 则根据所述切换信息执行无线切 换操作， 切入到所述目标电路域网络， 并对所述切换等待命令定时器复位； 或者当切换命令等待定时器溢出时， 没有接收到切换命令且无线接入可以继 续使用， 则所述单无线接入终端退出等待切换命令的状态， 继续使用源无线 接入网络。
该方法还包括远端分支媒体更新的步骤， 该步骤中， 所述业务连续性应 用服务器 SCC AS向会话远端发送媒体更新请求时不携带会话切换请求方提 供的媒体资源信息； 所述 SCC AS向所述会话远端发送确认消息时携带所述 媒体资源信息；所述会话远端根据收到的媒体资源信息改变媒体流发送方向。 为解决上述技术问题， 本发明还提供一种单无线接入方式下语音业务切 换的实现系统， 该系统包括源无线接入网络、 目标电路域网络、 互通网关及 单无线接入终端， 其中，
所述源无线接入网络设置为向互通网关 IWG发送电路域切换请求；还用 于接收所述 IWG发送的预切换指示信息及切换信息及向所述单无线接入终 端转发收到的预切换指示信息及切换信息；
所述目标电路域网络设置为与所述 IWG完成电路域切换准备过程； 所述 IWG设置为与所述目标电路域网络完成电路域切换准备过程；在接 入分支切换同时， 向所述源无线接入网络发送预切换指示信息及切换信息； 所述单无线接入终端设置为： 接收所述源无线接入网络发送的预切换指 示信息及切换信息， 根据预切换指示信息等待切换命令， 完成后续切换过程。
所述单无线接入终端是设置为根据所述预切换指示信息， 保存所述切换 信息， 同时启动切换命令等待定时器； 当所述单无线接入终端接收到切换命 令， 或当前正在使用的无线无法在满足通讯要求， 或切换命令等待定时器溢 出时， 根据所述切换信息执行无线切换操作， 切入到所述目标电路域网络以 及对所述切换等待命令定时器复位， 或者当切换命令等待定时器溢出时， 没 有接收到切换命令且无线接入可以继续使用， 退出等待切换命令的状态， 继 续使用源无线接入网络； 所述切换命令等待定时器的时长大于正常情况下 IMS会话切换完成更新的最大时间。
所述 IWG是设置为： 向所述源无线接入网络发送预切换响应消息， 其中 携带所述预切换指示信息及所述切换信息； 所述所述源无线接入网络是设置 为： 向单无线接入终端发送预切换通知消息， 其中携带所述预切换指示信息 及所述切换信息。
所述 IWG还设置为建立与目标电路域网络的电路连接。
该系统还包括业务连续性应用服务器 SCC AS及会话远端，
所述 SCC AS设置为： 向会话远端发送媒体更新请求， 所述媒体更新请 求中不携带会话切换请求方提供的媒体资源信息； 向所述会话远端发送确认 消息 , 所述确认消息中携带所述媒体资源信息；
所述会话远端设置为： 接收所述媒体更新请求及所述确认消息， 并根据 所述媒体资源信息改变媒体流发送方向。
为解决上述技术问题， 本发明还提供一种单无线接入方式下语音业务切 换的实现方法， 该方法包括： 当源无线接入网络决定将正在进行的语音业务 切换到目标电路域网络， 进行远端媒体更新时，
所述业务连续性应用服务器 SCC AS向所述 IMS会话远端发送媒体更新 请求 , 其中不携带会话切换请求方提供的媒体资源信息；
所述 SCC AS向所述 IMS会话远端发送确认消息， 其中携带所述会话请 求方提供的媒体资源信息； 以及
所述 IMS会话远端接收到所述确认消息后， 根据会话请求方提供的媒体 资源信息改变媒体流发送方向。
SCC AS是接收到会话切换请求后向所述 IMS会话远端发送所述媒体更新请 求的， 所述会话切换请求中携带会话切换请求方提供的媒体资源信息； 在所 述 SCC AS向所述 IMS会话远端发送确认消息的步骤中， 所述 SCC AS是在 消息的。
为解决上述技术问题， 本发明还提供另一种单无线接入方式下语音业务 切换的实现系统， 所述系统包括业务连续性应用服务器 SCC AS及会话远端， 其中，
所述 SCC AS设置为： 向会话远端发送媒体更新请求， 其中不携带会话 切换请求方提供的媒体资源信息； 向所述会话远端发送确认消息， 其中携带 所述媒体资源信息； 所述会话远端设置为接收所述媒体更新请求及所述确认 消息， 根据所述媒体资源信息改变媒体流发送方向。
所述 SCC AS还设置为： 接收会话切换请求， 接收所述会话远端返回的 媒体更新响应； 所述会话远端还设置为： 向所述 SCC AS返回媒体更新响应。
本发明方法和系统在目标电路域网络切换准备完成后， 在接入分支切换 同时向 UE发送预切换指示信息及切换信息。 当在高速移动和源无线接入信 号衰减很快的场合下， 即使发生有线切换过程比较长而导致的切换命令无法 通知到 UE的场景， UE也有能力根据预切换请求中携带的切换信息完成切换， 另外， 在远端媒体切换过程中， 本发明通过利用 SCC AS的控制功能， 改变 媒体资源信息到达会话远端的时间， 优化与远端 UE之间的媒体协商过程， 从而减少了下行媒体流切换中断时间。
附图概述
图 1是单无线接入方式下语音切换的业务场景示意图。
图 2是单无线接入方式下语音切换的架构示意图。
图 3是现有技术中单无线接入方式下的语音业务切换流程图。
图 4是现有技术中单无线接入方式下的另一语音业务切换流程图。
图 5是本发明单无线接入语音切换方法的第一实施例信令流程示意图。 图 6是本发明单无线接入语音切换方法的第二实施例信令流程示意图。 图 7是本发明单无线接入语音切换方法的第三实施例信令流程示意图。 图 8是本发明单无线接入方式语音业务切换的实现方法的流程示意图。
本发明的较佳实施方式
为了解决因媒体流切换时间长而导致的切换失败问题， 本发明提供了一 种单无线接入方式下语音业务切换的实现方法， 应用于单无线接入方式下语 音切换业务， 在远端媒体切换过程中， 通过利用 SCC AS的控制功能， 改变 媒体资源信息到达会话远端的时间， 优化与远端 UE之间的媒体协商过程， 从而减少了下行媒体流切换中断时间。
单无线接入 UE接入源无线接入网络，并通过 IMS建立与远端设备的 IMS 会话，其会话路径锚定在 SCC AS, 当源无线接入网络决定将正在进行的语音 业务切换到目标 CS 网络， 执行远端媒体更新时， 该单无线接入方式语音业 务切换的实现方法包括：
所述 SCC AS接收到会话切换请求方的会话切换请求后， 向所述 IMS会 话远端发送媒体更新请求， 其中不携带会话切换请求中会话切换请求方提供 的媒体资源信息； 所述 SCC AS接收到所述 IMS会话远端返回媒体更新响应后，向所述 IMS 会话远端发送确认消息， 其中携带会话切换请求方提供的媒体资源；
所述 IMS会话远端接收到所述确认消息后， 根据会话请求方提供的媒体 资源信息改变媒体流发送方向。
以下通过附图及具体实施例对以上单无线接入语音切换实现方法进行具 体说明：
第一实施例
图 5是本发明第一实施例的单无线接入语音切换流程图， 描述了 UE-A 在源无线接入覆盖区接入， 与远端 UE-B建立 IMS会话， 而后切换到 CS网 络下的过程。 本实施例和非语音媒体无关， 只考虑从源无线接入网络到目标 CS网络的切换过程。 其步骤描述如下：
步骤 501 ~ 508与图 4中的步骤 401 ~ 408相同。
509、 IWG使用切换标识 STN作为被叫号码， 使用初始地址消息（Initial Address Message, 简称 IAM )消息向 IMS发送切换请求， 请求 SCC AS执行 切换过程；
该步骤可以在步骤 507后执行， 与步骤 508并行执行。
510、 MGCF将 IAM转换成 SIP邀请消息（ INVITE ) , 经过 CSCF等网 元发送给 SCC AS, 并携带 MGW提供的媒体资源信息；
此时 MGW启动媒体资源信息中指示的本地媒体接收端口， 准备接收对 端发送的媒体流；
511、 SCC AS向远端 UE-B发送 SIP媒体更新请求（RE-INVITE ) , 不 携带媒体资源信息， 即空 SDP报文；
512、 UE-B返回 SIP确认响应， 并携带 UE-B提供的媒体资源信息； 其中确认响应可以是最终确认响应 （200 OK ) , 也可以是临时响应， 如 果是临时响应， 后续还要经过类似的媒体协商过程。
本文的实施例都以最终确认响应进行描述。
SCC AS根据步骤 510中获取的 MGW的媒体信息中的编码信息， 以及 本步骤获取的 UE-B 的媒体信息中的编码信息， 选取双方共同支持的编码格 式以及优先顺序。
此时 UE-B启动媒体资源信息中指示的本地媒体接收端口， 准备接收对 端发送的媒体流；本地媒体接收端口可以釆用原来正在使用的媒体接收端口， 也可以分配新的媒体接收端口； 如果使用新的媒体接收端口， 则在两个端口 同时接收， 当在新的端口接收的媒体后， 才关闭原来媒体接收端口， 这样保 证在改变端口过程中， 不丟失媒体。 由于此时 UE-A还在源无线接入网络， 因此 UE-B可以继续收到 UE-A发送的媒体流， 即接听不受影响。
另外， 由于步骤 511中没有携带媒体资源信息， UE-B没有接收到对端的 媒体资源信息， 将不改变原来的媒体流的发送方向， 即仍通过源承载- IMS 承载向 UE-A发送媒体。 因此和现有技术相比， 下行媒体仍然正常进行； 513、 SCC AS转发 200 OK到 MGCF, 携带 UE-B提供的媒体资源信息； 媒体信息中的编码格式以及顺序釆用步骤 512中 SCC AS选取的结果。 该步骤完成后， MGCF控制 MGW向 UE-B的媒体接收端口可以开始发 送媒体， 但由于 UE在釆用源承载的接收端口接收媒体流， 因此上行媒体流 没有中断。且由于 UE-A还没有切换到目标承载 ,因此 MGW没有接收到 UE-A 的媒体流， 不会向 UE-B发送媒体流。 此时， 由于 UE没有从目标承载的接收 端口接收到媒体流， 因此 UE-B不会关闭源承载的接收端口。
514、 MGCF向 IWG发送应答消息（ Answer Message, 简称 ANM )响应；
515、 MGCF同时向 SCC AS返回 SIP确认请求（ACK ) ；
516、 SCC AS向 UE-B发送 ACK确认消息， 携带在步骤 510中获取的 MGW提供的媒体资源信息；
媒体信息中的编码格式以及顺序釆用步骤 512中 SCC AS选取的结果。 该步骤 516可以在执行步骤 513的时候执行。 该步骤完成后， UE-B将改变媒体流的发送方向， 向步骤 516中指定的接 收端口， 即 MGW的媒体接收端口发送媒体， 停止从源承载路径 - IMS承载 向 UE-A的媒体接收端口发送媒体，此时 UE-A将无法接收到 UE-B发送的媒 体流， 表现为用户 A无法听到用户 B的声音。
当步骤 508和 516完成后， 完成 IMS会话的切换过程， 以及远端 UE的 媒体更新， 建立了从目标无线子系统-目标 MSC Server - MGCF/MGW - UE-B之间的目标媒体承载。
由于此时 UE-A还没有进行切换， 还在原来的承载发送和接收媒体， 而 UE-B的发送媒体已经切换到目标承载，但仍然可以在原端口接收媒体， 因此 从 UE-A到 UE-B的媒体流正常（称为上行媒体流 ) , UE-B到 UE-A的媒体 流终端 （称为下行媒体流）从步骤 516开始中断， 表现为单通。
步骤 517 - 519与图 4中步骤 417 ~ 419相同， 此时 UE-A切换到目标 CS 无线网络， 建立 UE-A和目标无线子系统见的目标承载： CS承载 1 , 从而完 成接入侧切换， 和远端 UE-B建立媒体连接， 通话恢复正常。 此时 UE-B从目 标承载的接收端口接收到媒体流， 如果源承载的接收端口与目标承载的接收 端口不同， UE-B将关闭源承载的接收端口。
步骤 520 ~ 523与图 4中步骤 420 ~ 423相同。
由上面的流程以及分析可以看出， 在切换过程中也存在语音中断时间， 且上行媒体流和下行媒体流的中断时间不同：
下行媒体流的中断时间基本是从步骤 516 UE-B接收到媒体更新请求开 始向 MGW发送下行媒体流起， 到步骤 519完成为止。 艮设步骤 516是在步 骤 515后执行， 且步骤 515、 516的处理和传输时间正好与步骤 514、 517、 518 的时间相等， 则中断时间为 T519, 如果两者不同， 则中断时间是 T519 加两者差值的绝对值。
上行的媒体流在 UE-A执行步骤 519之前， 一直通过源承载 - IMS承载 进行， 只是在步骤 519期间会中断， 因此上行媒体流的中断时间为 T519。
根据实际测量以及理论计算， T519约为 100ms, 因此上行媒体流的中断 时间约为 100ms, 下行媒体流的中断时间最短为 100ms, 其最大值也小远于 现有技术。 可以看出， 通过利用 SCC AS的控制功能， 改变媒体资源信息到 达会话远端的时间， 优化与远端 UE之间的媒体协商过程， 从而减少了下行 媒体流切换中断时间。
为了实现以上方法， 本发明还提供了一种单无线接入方式语音业务切换 的实现系统， 该系统包括 SCC AS及会话远端， 其中，
所述 SCC AS用于向会话远端发送媒体更新请求， 其中不携带会话切换 请求方提供的媒体资源信息； 还用于向所述会话远端发送确认消息， 其中携 带所述媒体资源信息；
所述会话远端用于接收所述媒体更新请求及所述确认消息， 还用于根据 所述媒体资源信息改变媒体流发送方向。
当然为了完整地完成以上语音业务切换过程， 该实现系统还应该包括源 无线接入网络、 目标网络、 互通网关及单无线接入终端等， 这里不再赘述。
为解决因切换时间过长而导致切换失败的问题， 本发明还提供了另一种 单无线接入方式语音业务切换的实现方法， 该方法的主要思想是在电路域切 换准备后， 在进行接入分支切换的同时， 互通网关 IWG通过源无线接入网络 向单无线接入终端发送预切换指示信息及切换信息， 使单无线接入终端进入 预切换状态。 鉴于切换过程长对高速移动的终端的影响， 本发明利用预切换 机制， 在进行 IMS会话切换的同时， IWG通知 UE进行切换准备， 等 IMS会 话切换完成后， 再正式通知 UE进行切换， 避免由于切换过程长无法通知 UE 进行切换的问题， 保证切换成功。
当源无线接入网络决定将单无线接入终端正在进行的语音业务切换到目 标电路域网络时， 如图 8所示， 该方法包括：
步骤 801： 所述源无线接入网络向互通网关 IWG发送电路域切换请求； 步骤 802: 所述 IWG与所述目标电路域网络完成电路域切换准备过程； 步骤 803: 在进行接入分支切换的同时， 所述 IWG通过所述源无线接入 网络向所述单无线接入终端发送预切换指示信息及切换信息； 所述 IWG通过所述源无线接入网络向所述单无线接入终端发送所述预 切换指示信息及所述切换信息包括：所述 IWG向所述源无线接入网络发送预 切换响应消息， 其中携带所述预切换指示信息及所述切换信息； 所述源无线 接入网络向所述单无线接入终端发送预切换通知消息， 其中所述预切换指示 信息及所述切换信息。
这里的预切换响应消息及预切换通知消息都是新定义的消息， 当然也可 以釆用原有消息携带以上预切换指示信息及所述切换信息。
所述 IWG 向所述源无线接入网络发送预切换响应消息是在所述切换准 备过程完成后， 与所述 IWG建立目标电路域网络电路连接并行执行的， 或在 IWG建立目标电路域网络电路连接之后执行的。
步骤 804: 所述单无线接入终端保存所述切换信息， 等待切换命令， 完 成后续切换过程。
所述单无线接入终端启动切换命令等待定时器； 当所述单无线接入终端 接收到切换命令， 或当前正在使用的无线无法在满足通讯要求， 或切换命令 等待定时器溢出时， 则根据所述切换信息执行无线切换操作， 切入到所述目 标电路域网络。 也可以是， 当切换命令等待定时器溢出时， 没有接收到切换命令且无线 接入可以继续使用， 则 UE退出等待切换命令的状态， 继续使用源无线接入 网络。 这种方法可以防止网络侧的会话切换没有完成， 产生异常。
若后续接收的切换命令中的切换信息与单无线接入终端保存的切换信息 不同， 以切换命令中的切换信息为准。
所述切换命令等待定时器的时长大于正常情况下 IMS会话切换完成更新 的最大时间， 且所述单无线接入终端在执行无线切换操作时对所述切换等待 命令定时器复位。
以下通过具体实施例及附图对本发明第二种方法进行说明：
第二实施例
图 6是本发明第二实施例的单无线接入方式下的切换过程示意图。 描述 了 UE-A在源无线接入覆盖区接入， 与远端 UE-B建立 IMS会话， 而后切换 到 CS网络下的过程， 其过程包括以下步骤：
601、 当 UE从源无线网络接入 IMS , 并进入通话态时， UE定时检测周 围的无线环境， 通过测量报告通知源无线接入网路；
602、 源无线接入网络根据本地的配置检查当前的无线通讯条件， 如果发 现当前所使用的无线接入不再适合进行通讯，比如信号强度低于设定的阔值， 将从 UE上报的周围无线网络的信息选择切换的目标网络；
603、 源无线接入网络发现通讯媒体中含有语音， 向 IWG发送 CS切换 请求， 携带目标 CS 网络的小区信息、 用户标识以及会话转移号码（Session Transfer Number, 简称 STN )等信息， 通知 IWG进行切换； 执行步骤 605;
604、 与步骤 603同时， 如果通讯媒体中还含有非语音的 PS媒体， 且目 标网络和终端同时支持 CS和 PS接入， 则向目标 PS网络发送 PS切换请求； 转执行步骤 606;
605、 IWG收到源无线接入网络的切换请求， 利用 CS现有的切换机制， 完成无线资源准备；
在步骤完成后， IWG和目标 CS网络建立 CS电路连接， 该步骤和步骤 606、 607无关， 可以和步骤 606、 607同时执行。
606、 IWG向源无线接入网路返回 CS预切换响应消息， 表示切换准备完 成， 并携带预切换指示信息及切换信息；
该消息中携带的切换信息包含目标 CS接入网的属性、 以及详细接入信 息。
该消息可以是新定义的消息， 如预切换响应消息， 或在现有的 CS切换 响应中增加指示， 指示该消息是 CS预切换响应消息。
607、 IWG然后向 IMS发送会话切换请求， 建立切入呼叫分支， 代替原 来通过源无线接入网络建立的切出呼叫分支， 实现接入分支切换及远端媒体 更新；
608、 目标 PS网络接收到步骤 604的 PS切换请求， 完成 PS切换准备过 程； 609、 当步骤 608完成后， 目标 PS网络向源无线接入网络返回 PS切换响 应， 表示切换准备完成， 并携带切换信息；
610、 源无线接入网络接收步骤 606中 CS预切换响应消息和步骤 609中 的 PS切换响应， 知道目标网络准备完成， 但语音媒体的切换还没有完成， 则 向 UE发送预切换通知消息， 携带详细的切换信息， 包括目标网络（包括 CS 网络和 PS网络） 的详细接入信息；
UE接收到预切换通知消息请求，保存与目标网络的切换信息， 启动切换 命令等待定时器， 等待切换命令。
此时， UE并不执行无线切换过程， 当接收到切换命令， 或当前正在使用 的无线接入方式无法在满足通讯要求， 如移动出源无线接入网络的覆盖区， 或切换命令等待定时器溢出， 则 UE根据切换信息执行无线切换操作， 切换 到切换命令指定的目标无线网络， 或预切换请求中指定的目标无线网络， 并 复位切换命令等待定时器。 也可以是， 当切换命令等待定时器溢出时， 没有 接收到切换命令且无线接入可以继续使用， 则 UE退出等待切换命令的状态， 继续使用源无线接入网络。
在预切换中， IWG可以通过源无线接入网络发送切换取消请求， 或源无 线接入网络向 UE发送切换取消请求， UE接收到该请求后， 复位切换命令等 待定时器， 退出等待切换命令的状态。
在预切换中， UE可以根据具体的实现方式，提前完成一些切换的准备工 作， 如硬件电路的启动、 电路域软件模块、 切换模块的加载初始化能工作， 以加快切换速度。
如果 UE或源无线接入网路不支持切换通知请求， 将该请求作为未知消 息， 不做处理或返回未知请求， 而不会影响正常的切换过程。
预切换通知消息携带的切换信息包含目标接入网的属性、 以及详细接入 信息， 包括目标 CS接入网网络和 /或目标 CS接入网网络的详细接入信息。该 消息可以是新定义的消息， 或在现有的切换命令中增加指示， 指示该消息是 预切换通知消息。
611、 UE等待切换命令； 612、 当步骤 607完成后， IWG向源无线接入网路返回 CS切换响应， 表 示切换准备和 IMS切换完成， 并携带切换信息；
613、 源无线接入网络接收步骤 612中 CS切换响应和步骤 609中的 PS 切换响应， 则向 UE发送切换命令。
614、 UE执行切换， 切换到目标网络。
图 7是本发明第二实施例的单无线接入语音切换流程图， 描述了 UE-A 在源无线接入覆盖区接入， 与远端 UE-B建立 IMS会话， 而后切换到 CS网 络下的过程。
第三实施例
预切换机制也可以和第一实施例所提及的减少下行媒体流切换中断时间 方法同时使用。 本实施例， 只描述有语音媒体的场景。 如图 7所示， 其切换 过程包括以下步骤：
步骤 701 ~ 708与图 4中的步骤 501 ~ 508相同 .
709、 IWG使用切换标识 STN作为被叫号码， 使用初始地址消息（Initial
Address Message, 简称 IAM )消息向 IMS发送切换请求， 请求 SCC AS执行 切换过程；
该步骤可以在步骤 707后执行， 与步骤 708并行执行。
717a, IWG向源无线接入网络发送预切换命令消息， 携带在步骤 707中 获取的切换信息；
本步骤标号不表明执行顺序， 只是为了方便说明， 以便和步骤 717、 以 及图 4、 图 5中步骤 417、 517建立比对关系。
本步骤在图中的顺序， 并不表明实际执行顺序， 可以和在步骤 707后执 行， 与步骤 708、 709并行执行。
718a,源无线接入网络向 UE-A发送预切换通知消息，指示 UE-A网络已 经决策准备进行切换， 以及切换目标 CS无线网络的切换信息。
本步骤标号不表明执行顺序，只是为了方便说明，和步骤 718、以及图 4、 图 5中步骤 418、 518建立对应关系。
UE-A接收到预切换通知消息请求，保存与目标 CS无线网络的切换信息， 启动切换命令等待定时器， 等待切换命令。
步骤 710 ~ 716与图 5中的步骤 510 ~ 516相同，完成 IMS会话切换过程， 以及远端 UE 的媒体更新， 建立了从目标无线子系统-目标 MSC Server - MGCF/MGW - UE-B之间的目标媒体承载，媒体流的中断的情况与图 5相同。
步骤 717 ~ 719与图 5中步骤 517 ~ 519相同， IWG在 IMS会话切换完成， 媒体路径准备完成后， 经过源无线接入网络发送切换请求， UE-A切换到目标 CS无线网络， 建立 UE-A和目标无线子系统间的目标承载： CS承载 1 , 从而 完成 IMS会话切换， 建立和远端 UE-B的媒体连接， 通话恢复正常。
如果由于用户已经移出源无线接入网络， 导致在向步骤 718的切换命令 无法发送到 UE-A, 且源无线接入网络发送过预切换通知到 UE-A, 则源无线 网络认为 UE-A已经切出源无线接入网络。
如果用户已经切换到目标 CS网络， 此时 IMS会话切换工作才完成， 即 步骤 712比步骤 714提前到达 IWG,则 IWG可以在步骤 714后继续执行步骤 717发送切换命令， 或跳过步骤 717, 直接执行步骤 721 , 通知源无线接入网 络切换已经完成。
为了实现以上第三实施例的单无线接入方式下语音业务切换方法， 本发 明还提供一种单无线接入方式下语音业务切换的实现系统， 该系统包括源无 线接入网络、 目标网络、 互通网关、 单无线接入终端 SCC AS及会话远端， 其中，
所述源无线接入网络， 用于向互通网关 IWG发送电路域切换请求； 还用 于接收所述 IWG发送的电路域切换指示信息及切换信息及向所述单无线接 入终端转发收到的预切换指示信息及切换信息；
所述源无线接入网络通过预切换通知消息向所述单无线接入终端发送所 述预切换指示信息及所述切换信息。 所述目标网络， 用于与所述 IWG完成电路域切换准备过程； 在进行接入分支切换的同时， 向所述源无线接入网络发送预切换指示信息及 切换信息；
所述 IWG通过预切换响应消息向所述源无线接入网络发送所述预切换 指示信息及所述切换信息；
所述单无线接入终端用于接收所述源无线接入网络发送的电路域切换指 示信息及切换信息， 还用于保存所述切换信息， 以及根据预切换指示信息等 待切换命令， 完成后续切换过程。
所述单无线接入终端还用于同时启动切换命令等待定时器； 当所述单无 线接入终端接收到切换命令， 或当前正在使用的无线无法在满足通讯要求， 或切换命令等待定时器溢出时， 所述单无线接入终端还用于根据所述切换信 息执行无线切换操作， 切入到所述目标电路域网络。 也可以是， 当切换命令 等待定时器溢出时， 没有接收到切换命令且无线接入可以继续使用， 则 UE 退出等待切换命令的状态， 继续使用源无线接入网络。
所述 SCC AS在远端媒体更新过程中， 用于向会话远端发送媒体更新请 求， 其中不携带会话切换请求方提供的媒体资源信息； 还用于向所述会话远 端发送确认消息， 其中携带所述媒体资源信息；
这里所说的会话切换请求方指媒体网关 MGW。
所述会话远端用于根据收到的媒体资源信息改变媒体流发送方向。
由上面的流程以及分析可以看出， 本发明方法和系统在接入分支切换的 同时向 UE发送预切换指示信息及切换信息。 当在高速移动和源无线接入信 号衰减很快的场合下， 即使发生有线切换过程比较长而导致的切换命令无法 通知到 UE的场景， UE也有能力根据预切换请求中携带的切换信息完成切换， 从而保证在 IMS会话切换过程比较长的情况下， 能进行正常的切换， 且优化 了中断时间。 工业实用性 本发明方法和系统在目标电路域网络切换准备完成后， 在接入分支切换 同时向 UE发送预切换指示信息及切换信息。 当在高速移动和源无线接入信 号衰减很快的场合下， 即使发生有线切换过程比较长而导致的切换命令无法 通知到 UE的场景， UE也有能力根据预切换请求中携带的切换信息完成切换， 另外， 在远端媒体切换过程中， 本发明通过利用 SCC AS的控制功能， 改变 媒体资源信息到达会话远端的时间， 优化与远端 UE之间的媒体协商过程， 从而减少了下行媒体流切换中断时间。

Claims

权 利 要 求 书
1、 一种单无线接入方式下语音业务切换的实现方法，该方法包括： 当源 无线接入网络决定将单无线接入终端正在进行的语音业务切换到目标电路域 网络时，
所述源无线接入网络向互通网关 IWG发送电路域切换请求；
所述 IWG与所述目标电路域网络完成电路域切换准备过程；
在接入分支切换的同时，所述 IWG通过所述源无线接入网络向所述单无 线接入终端发送预切换指示信息及切换信息； 以及
所述单无线接入终端根据所述预切换指示信息等待切换命令， 完成后续 切换过程。
2、 如权利要求 1所述的方法， 其中， 所述 IWG通过所述源无线接入网 络向所述单无线接入终端发送所述预切换指示信息及所述切换信息的步骤包 括： 所述 IWG向所述源无线接入网络发送预切换响应消息， 其中携带所述预 切换指示信息及所述切换信息； 所述源无线接入网络向所述单无线接入终端 发送预切换通知消息， 其中携带所述预切换指示信息及所述切换信息。
3、 如权利要求 2所述的方法， 其中，
所述方法在所述完成电路域切换准备过程的步骤之后还包括， IWG建立 与目标电路域网络的电路连接；
所述 IWG 向所述源无线接入网络发送预切换响应消息的步骤是与所述 IWG建立与目标电路域网络的电路连接的步骤并行执行的，或是在所述 IWG 建立与目标电路域网络的电路连接的步骤之后执行的。
4、 如权利要求 1所述的方法，其中， 所述单无线接入终端根据所述预切 换指示信息等待切换命令， 完成后续切换过程的步骤包括：
所述单无线接入终端根据所述预切换指示信息， 保存所述切换信息， 同 时启动切换命令等待定时器； 所述切换命令等待定时器的时长大于正常情况 下 IP多媒体子系统 IMS会话切换完成更新的最大时间； 当所述单无线接入终端接收到切换命令， 或当前正在使用的无线无法在满足 通讯要求， 或切换命令等待定时器溢出时， 根据所述切换信息执行无线切换 操作， 切入到所述目标电路域网络， 并对所述切换等待命令定时器复位； 或 者当切换命令等待定时器溢出时， 没有接收到切换命令且无线接入可以继续 使用， 则所述单无线接入终端退出等待切换命令的状态， 继续使用源无线接 入网络。
5、 如权利要求 1所述的方法，其中，该方法还包括远端分支媒体更新的 步骤， 该步骤中， 所述业务连续性应用服务器 SCC AS向会话远端发送媒体 更新请求时不携带会话切换请求方提供的媒体资源信息； 所述 SCC AS向所 述会话远端发送确认消息时携带所述媒体资源信息； 所述会话远端根据收到 的媒体资源信息改变媒体流发送方向。
6、 一种单无线接入方式下语音业务切换的实现系统，该系统包括源无线 接入网络、 目标电路域网络、 互通网关 IWG及单无线接入终端， 其中，
所述源无线接入网络设置为： 向发送电路域切换请求； 接收所述 IWG发 送的预切换指示信息及切换信息； 以及向所述单无线接入终端转发收到的预 切换指示信息及切换信息；
所述目标电路域网络设置为与所述 IWG完成电路域切换准备过程； 所述 IWG设置为： 与所述目标电路域网络完成电路域切换准备过程； 在 接入分支切换同时，向所述源无线接入网络发送预切换指示信息及切换信息； 所述单无线接入终端设置为： 接收所述源无线接入网络发送的预切换指 示信息及切换信息， 根据所述预切换指示信息等待切换命令， 完成后续切换 过程。
7、 如权利要求 6所述的系统， 其中： 所述单无线接入终端是设置为： 根 据所述预切换指示信息， 保存所述切换信息， 同时启动切换命令等待定时器； 当所述单无线接入终端接收到切换命令， 或当前正在使用的无线无法在满足 通讯要求， 或切换命令等待定时器溢出时， 根据所述切换信息执行无线切换 操作， 切入到所述目标电路域网络以及对所述切换等待命令定时器复位， 或 者当切换命令等待定时器溢出时， 没有接收到切换命令且无线接入可以继续 使用， 退出等待切换命令的状态， 继续使用源无线接入网络； 所述切换命令 等待定时器的时长大于正常情况下 IP多媒体子系统 IMS会话切换完成更新的 最大时间。
8、 如权利要求 6所述的系统， 其中， 所述 IWG是设置为： 向所述源无 线接入网络发送预切换响应消息， 其中携带所述预切换指示信息及所述切换 信息； 所述所述源无线接入网络是设置为： 向单无线接入终端发送预切换通 知消息， 其中携带所述预切换指示信息及所述切换信息。
9、 如权利要求 8所述的系统， 其中， 所述 IWG还设置为建立与目标电 路域网络的电路连接。
10、 如权利要求 6所述的系统， 其中， 该系统还包括业务连续性应用服 务器 SCC AS及会话远端，
所述 SCC AS设置为： 向会话远端发送媒体更新请求， 所述媒体更新请 求中不携带会话切换请求方提供的媒体资源信息； 向所述会话远端发送确认 消息， 所述确认消息中携带所述媒体资源信息；
所述会话远端设置为： 接收所述媒体更新请求及所述确认消息， 并根据 所述媒体资源信息改变媒体流发送方向。
11、 一种单无线接入方式下语音业务切换的实现方法， 该方法包括， 当 源无线接入网络决定将正在进行的语音业务切换到目标电路域网络， 进行远 端媒体更新时，
所述业务连续性应用服务器 SCC AS向所述 IP多媒体子系统 IMS会话远 端发送媒体更新请求， 其中不携带会话切换请求方提供的媒体资源信息； 所述 SCC AS向所述 IMS会话远端发送确认消息， 其中携带所述会话请 求方提供的媒体资源信息； 以及
所述 IMS会话远端接收到所述确认消息后， 根据会话请求方提供的媒体 资源信息改变媒体流发送方向。
12、 如权利要求 8所述的方法， 其中，
SCC AS是接收到会话切换请求后向所述 IMS会话远端发送所述媒体更新请 求的 , 所述会话切换请求中携带会话切换请求方提供的媒体资源信息；
发送确认消息的。
13、 一种单无线接入方式下语音业务切换的实现系统， 所述系统包括业 务连续性应用服务器 SCC AS及会话远端， 其中，
所述 SCC AS设置为： 向会话远端发送媒体更新请求， 其中不携带会话 切换请求方提供的媒体资源信息； 向所述会话远端发送确认消息， 其中携带 所述媒体资源信息；
所述会话远端设置为： 接收所述媒体更新请求及所述确认消息， 并根据 所述媒体资源信息改变媒体流发送方向。
14、 如权利要求 13所述的系统， 其中，
所述 SCC AS还设置为： 接收会话切换请求， 接收所述会话远端返回的 媒体更新响应；
所述会话远端还设置为： 向所述 SCC AS返回媒体更新响应。
PCT/CN2010/071328 2009-03-25 2010-03-25 单无线接入方式语音切换的实现方法及系统 WO2010108447A1 (zh)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN200910132329.2 2009-03-25
CN200910132329.2A CN101848517B (zh) 2009-03-25 2009-03-25 单无线接入方式语音切换的实现方法及系统

Publications (1)

Publication Number Publication Date
WO2010108447A1 true WO2010108447A1 (zh) 2010-09-30

Family

ID=42772937

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2010/071328 WO2010108447A1 (zh) 2009-03-25 2010-03-25 单无线接入方式语音切换的实现方法及系统

Country Status (2)

Country Link
CN (1) CN101848517B (zh)
WO (1) WO2010108447A1 (zh)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111542072A (zh) * 2015-09-16 2020-08-14 华为技术有限公司 移动性管理的方法、用户设备和基站

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8914027B2 (en) * 2009-06-25 2014-12-16 Htc Corporation Method of initiating handover pre-preparation and related communication device
CN103200149A (zh) * 2012-01-04 2013-07-10 中兴通讯股份有限公司 一种反向单待业务连续性实现方法和装置
WO2013149654A1 (en) 2012-04-03 2013-10-10 Telefonaktiebolaget L M Ericsson (Publ) Hold announcement configuration
CN108156634B (zh) * 2016-12-02 2022-08-19 中兴通讯股份有限公司 业务处理方法、装置及系统

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050036492A1 (en) * 2003-07-31 2005-02-17 Klaus Hoffmann Method for redirecting a bearer connection (bearer redirect) for SIP/ SIP-T subscribers
CN1882175A (zh) * 2005-09-19 2006-12-20 华为技术有限公司 无线切换方法及系统
WO2007100960A2 (en) * 2006-02-22 2007-09-07 Motorola, Inc. Method and system for seamless media handover across devices
WO2009003067A2 (en) * 2007-06-25 2008-12-31 Qualcomm Incorporated Recovery from handoff error due to false detection of handoff completion signal at access terminal

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050036492A1 (en) * 2003-07-31 2005-02-17 Klaus Hoffmann Method for redirecting a bearer connection (bearer redirect) for SIP/ SIP-T subscribers
CN1882175A (zh) * 2005-09-19 2006-12-20 华为技术有限公司 无线切换方法及系统
WO2007100960A2 (en) * 2006-02-22 2007-09-07 Motorola, Inc. Method and system for seamless media handover across devices
WO2009003067A2 (en) * 2007-06-25 2008-12-31 Qualcomm Incorporated Recovery from handoff error due to false detection of handoff completion signal at access terminal

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111542072A (zh) * 2015-09-16 2020-08-14 华为技术有限公司 移动性管理的方法、用户设备和基站
CN111542072B (zh) * 2015-09-16 2023-11-10 华为技术有限公司 移动性管理的方法、用户设备和基站

Also Published As

Publication number Publication date
CN101848517B (zh) 2015-05-13
CN101848517A (zh) 2010-09-29

Similar Documents

Publication Publication Date Title
JP4763723B2 (ja) 回線交換無線ネットワークとパケット交換データ無線ネットワークとの間における呼ハンドオフのためのシステムと方法
US9307453B2 (en) Method, device and system for processing reverse single radio voice call continuity
RU2480947C2 (ru) Система и способ для sr-vcc экстренных сеансов ims
JP4820949B2 (ja) ハイブリッド加入者ユニットのシステム間アクティブ・ハンドオフのための方法および装置
KR101446028B1 (ko) 패킷 스위칭된 도메인으로부터 회로 스위칭된 도메인으로 비디오 호를 핸드 오버하기 위한 방법 및 디바이스
US8644258B2 (en) Method and apparatus for reducing break duration in handover of VoIP conversation
US20160157136A1 (en) Communication terminal apparatus and communication method
US9706449B2 (en) Technique for transferring a session with changeable session state
WO2011011922A1 (zh) 非稳定VoIP呼叫中的终端切换方法、网络单元、设备及系统
WO2008059570A1 (fr) Appareil de terminal de communication, système de communication, et procédé de transfert continu
JP2010517429A (ja) パケット交換ドメインと回線交換ドメインとの間におけるハンドオフの性能を改善する方法
EP2920998A1 (en) A method and system for improved ps to cs handover of a user equipment
WO2010108447A1 (zh) 单无线接入方式语音切换的实现方法及系统
WO2011050530A1 (zh) 减小isc会话切换中的信令延迟的方法、网络单元和系统
WO2010127511A1 (zh) Srvcc切换及其数据传输的方法、装置和系统
WO2012149866A1 (zh) 单一无线语音呼叫连续性域的切换方法及系统
US8982840B2 (en) Handover
EP2232735B1 (en) Method and apparatus for inter-technology handoff of a terminating mobile station during an alerting procedure
WO2011023054A1 (zh) 一种ip多媒体子系统中多会话能力同步方法及系统
KR101071474B1 (ko) 와이브로 시스템과 ｃｄｍａ 시스템 간의 ｓｉｐ 메시지를이용한 핸드오버 방법
KR20130097355A (ko) 다중 패킷 전송 방식을 이용한 심리스 핸드오버 처리방법
KR101558230B1 (ko) 패킷 스위칭된 도메인으로부터 서킷 스위칭된 도메인으로 호 핸드오버 방법 및 장치
WO2008125067A1 (fr) Procédé et dispositif permettant d'assurer la continuité de données vocales au cours d'une session
WO2010133179A1 (zh) 实现电路交换cs切换方法、设备及系统

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 10755447

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 10755447

Country of ref document: EP

Kind code of ref document: A1