WO2009089745A1

WO2009089745A1 - A method and system for backspacing to the circuit switching domain to establish a voice call

Info

Publication number: WO2009089745A1
Application number: PCT/CN2008/073775
Authority: WO
Inventors: Jiyong Wang; Yongjun Yu; Yang Zhao; De Chen; Xiaobo Wu; Xiaoqin Duan; Jian Zhang
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2007-12-29
Filing date: 2008-12-26
Publication date: 2009-07-23
Also published as: CN101472349B; BRPI0821669B1; CN102149156A; CN102149156B; BR122015026582B1; CN101472349A; BRPI0821669A2

Abstract

A method for backspacing to the circuit switching domain to establish a voice call is provided. The method includes: the network side transmits an indication for establishing a voice call in the circuit switching domain to the user equipment, the indication is used to indicate the user equipment to reselect a cell having the circuit switching domain while a voice call is initiated according to the indication, and the voice call is established in the circuit switching domain of the cell. The embodiment of the present invention also discloses a system for backspacing to the circuit switching domain to establish a voice call, which can realize the continuity of the user's voice call wile the user equipment moves out a cell having the packet switching domain and moves in a cell having the circuit switching domain.

Description

Method and system for backing up to a circuit switched domain to establish a voice call

This application claims priority to Chinese Patent Application filed on Dec. 29, 2007, the Chinese Patent Office, Application No. 200710307877.5, entitled "Returning to the CS Domain to Establish Voice Calls, Systems, and Related Methods and Equipment", The entire contents of this application are incorporated herein by reference.

Technical field

The present invention relates to the field of communications, and more particularly to a method and system for backing up to a circuit switched domain to establish a voice call.

Background technique

After years of deployment, 2G/3G (Second Generation Mobile Communication Technology / Third Generation Mobile Communication Technology) network can be regarded as a comprehensive coverage to some extent. Today, with the development of technology, SAE (System Architecture Evolution)/LTE (Long Term Evolution), HSPA (High-Speed Packet Access), HSPA+ (High-speed Packet Access Evolution) And the WiMAX (Worldwide Interoperability for Microwave Access) network has been covered in some areas, so that in the current communication network, these networks coexist with 2G/3G networks. For the description, SAE/LTE, HSPA, HSPA+, WiMAX, etc., which only provide PS (packet switching) domain, are collectively referred to as pure PS domain networks.

For different network bearer mechanisms, voice calls for mobile communication can be classified into the following categories: The first type is a session type service carried by a CS (Circuit Switching) domain, such as a voice call;

The second type is the session-type service carried by the PS domain, also known as VoIP (voice over Internet Protocol)-based services. QoS (Quality of Service) is provided by IMS (IP Multimedia Subsystem). ) Guaranteed, such as IP-hosted voice calls.

For a pure PS domain network, voice calls can only be transmitted on their PS domain bearers, and IMS controls voice calls over IP-based networks. In a 2G/3G network, voice calls are typically carried on the CS domain.

The user who initiates the call may span the two networks during a call. Due to the different bearer mechanisms of the mobile communication service, when the UE (User Equipment) moves out of the pure PS domain (eg, SAE/LTE), the network base station Coverage, when entering the 2G/3G network base station coverage area, Intermittent IMS voice calls can occur, thereby affecting the continuity of the user's voice call.

In order to solve the above problems and ensure the continuity of voice calls of users, three types of technical solutions are currently used, as follows:

SRVCC (Single Radio Voice Call Continuity) technology solution, CS over PS (PS-bearing CS) technology solution and Redirection (relocation) technology solution.

Among them: SRVCC technical solution requirements: Deploy IMS; need a gateway node responsible for PS and CS signaling conversion or the network itself supports PS switching, DTM (Dual Transfer Mode).

The CS over PS technology solution currently has an eMSC (evolved Mobile Switching Center) solution and a Page in LTE (LTE paging), call in 2G/3G ( ² G/3G call setup) scheme.

The eMSC solution requires the deployment of eMSC.

Page in LTE, call in 2G/3G scheme is based on the update process of TA (Tracking Area) / LA (Location Area) combination, and LA update is triggered during TA update. The paging messages of all called voice calls are from the 2G/3G MSC (Mobile Switching Center). The paging message is forwarded by the MSC to the MME (Mobility Management Entity), and then sent by the MME to the evolved Node B (eNB). The eNB does not continue to deliver, but It is switched to a 2G/3G network through PS switching, and a call is established in the CS domain of the 2G/3G network.

Page in LTE, call in 2G/3G scheme requirements: The network supports PS handover and DTM; TA/TA list and LA restricted mapping relationship, that is, one TA/TA list cannot span two or more MSCs. Administered LA. In the early deployment phase of LTE, IMS may not be deployed, and most GSM networks do not support PS switching and DTM. Moreover, the limited mapping relationship between TA/TA list and LA limits the flexibility of LTE deployment. Therefore, the prior art cannot solve the IMS voice when the UE moves out of the PS domain (for example, the coverage area of the SAE/LTE network base station) and enters the cell with the CS domain (for example, the 2G/3G network base station coverage area). The discontinuity of the call results in a technical problem that affects the continuity of the user's voice call.

Summary of the invention Embodiments of the present invention provide a method and system for establishing a voice call back to a circuit switched domain, which can improve the continuity of a user's voice call when a user terminal moves out of a cell with a packet switched domain and enters a cell with a circuit switched domain.

The embodiments of the present invention are implemented by the following technical solutions:

An embodiment of the invention provides a method for establishing a voice call back to a circuit switched domain, the method comprising:

The network side sends an indication to the user terminal to establish a voice call to the circuit switched domain, the indication is used to indicate that the user terminal reselects a cell with a circuit switched domain when initiating a voice call according to the indication, and in the cell The circuit switched domain establishes a voice call.

Another embodiment of the present invention further provides a method for establishing a voice call back to a circuit switched domain, including:

The evolved node receives the voice call paging message sent by the mobile switching center through the preset logical function entity and the mobility management entity;

Parsing and processing the received voice call paging message, generating a cell change command; transmitting the cell change command to the user terminal, to instruct the user terminal to reselect to the target cell having the circuit switched domain according to the cell change command Establishing a voice call in the circuit switched domain of the target cell.

A further embodiment of the present invention further provides a system for backing up to a circuit switched domain to establish a voice call, including:

a network side, configured to send, to the user terminal, an indication that the voice call is established to the circuit switched domain; the indication is used to instruct the user terminal to initiate a voice call according to the indication, and reselect the cell with the circuit switched domain, and A circuit switched domain of the cell establishes a voice call.

Still another embodiment of the present invention provides a system for backing up a circuit call to establish a voice call, including:

Evolved node, used for

Receiving a voice call paging message sent by the mobile switching center through the preset logical function entity and the mobility management entity;

Parsing and processing the received voice call paging message, generating a cell change command; sending the cell change command to the user terminal, to instruct the user terminal to change according to the cell The variable command is reselected to the target cell with the circuit switched domain, and a voice call is established in the circuit switched domain of the target cell.

The technical effect of the embodiment of the present invention is: sending an indication to the user terminal through the network, the user terminal reselecting to the cell having the circuit switched domain; and establishing a voice call in the circuit switched domain of the cell. When the user terminal moves out of the cell of the packet switched domain and enters the cell with the circuit switched domain, the discontinuity of the IMS voice call causes a technical problem that affects the continuity of the user's voice call.

DRAWINGS

FIG. 1 is a system architecture of a solution A according to an embodiment of the present invention;

2 is a system architecture of a solution B according to an embodiment of the present invention;

3 is a structure and a flowchart of a TA update process triggering and completing an LA update in the scenario B of the first embodiment of the present invention;

4( _a ) and FIG. 4 ( b ) are diagrams showing a structure and a flow chart of the network of the second embodiment of the present invention indicating whether the UE voice call is transferred to the CS domain of the 2G/3G cell;

FIG. 5 is a flowchart of establishing a calling voice call by a UE reselecting to a 2G/3G cell according to Embodiment 3 of the present invention; FIG. 6 is a cell change of an LTE network that does not support network control according to Embodiment 4 of the present invention, where the UE reselects

A flow chart for establishing a calling voice call in a 2G/3G cell;

7 is a flowchart of a cell change control UE to a 2G/3G cell to establish a calling voice call according to Embodiment 4 of the present invention;

8 is a flowchart of establishing a called voice call by a UE autonomously reselecting to a 2G/3G cell according to Embodiment 5 of the present invention;

9 is a LTE network control UE reselecting to a 2G/3G cell to establish a called voice call according to Embodiment 6 of the present invention;

FIG. 10 is a flowchart of establishing a called voice call by a UE that reselects to a 2G/3G cell by using a VMSC-R as a back-to-back CS proxy mode according to an embodiment of the present invention;

FIG. 11 is a schematic structural diagram of a system for establishing a voice call back to a CS domain according to an embodiment of the present invention;

FIG. 12 is a schematic structural diagram of another system for establishing a voice call back to the CS domain according to an embodiment of the present invention;

FIG. 13 is a schematic structural diagram of a system for implementing a called flow according to an embodiment of the present invention. detailed description

In the embodiment of the present invention, when the UE is in the coverage of the LTE network, the UE registers the CS domain with the virtual LA, so that the UE can still receive the voice call of the CS domain when the UE camps on the LTE network.

In particular, when the UE camps on the LTE network, the virtual LA area is approximately equivalent to the area of LA at the same physical location 2G/3G. Since the LA of the 2G/3G is composed of 2G/3G cells, and the virtual LA area for the LTE network is composed of LTE cells, when the UE camps on the LTE network, the virtual LA area composed of the LTE cells and the same location area are composed of The LA regions composed of 2G/3G cells do not completely overlap.

When the UE camps on the LTE network, one MSC is selected according to the virtual LA area composed of the LTE cells. However, the UE falls back to the 2G/3G cell, and the 2G/3G cell may belong to another LA, so that the UE may select another MSC.

Depending on whether it is necessary to upgrade the MSC to support the transmission of the MSC to MME voice call paging message, there may be two schemes, scheme A and scheme B. Scenario A needs to upgrade the MSC to support sending a voice call paging message to the MME. Solution B adds a Mobility proxy (mobile function entity) responsible for forwarding LA update and voice call paging messages between the MSC and the MME.

From the perspective of the MSC, the Mobility proxy is a BSS (Base Station System) / RNS (Radio Network Subsystem), and all LAs that are mapped to the TA/TA list contain this Mobility. The proxy simulates the BSS/RNS, and these TA/TA lists belong to the MME connected to the Mobility proxy. By configuring LA to join the BSS/RNS simulated by the Mobility proxy, the MSC can perform LA update and send voice call paging messages according to standard procedures. If the UE wants to reselect the 2G/3G cell to establish the called voice call, the two methods are required to forward the voice call paging message. If the UE wants to reselect the 2G/3G cell to establish the calling voice call, The above two schemes are not required to forward the voice call paging message. The system architecture of these two schemes is shown in Figure 1 and Figure 2.

The specific configuration method is that each LTE cell (the cell of the pure PS domain) has its corresponding TA/TA list and LA, and each LA to be updated by the Mobility proxy includes the BSS simulated by the Mobility proxy. /RNS, so that the LA update and the voice call paging message can be forwarded to the UE via the LTE network without modifying the GSM protocol specification. The interface between the Mobility proxy and the MME is S3, (simplified S3 interface, only LA update and paging messages are transmitted), when the UE switches from the SAE/LTE network to the 2G/3G network or when it is from the 2G/3G network to the SAE/ When the LTE network is switched, all the switching is eliminated. The information is passed through the Mobility proxy, Mobility proxy—directly on the path of the S3 interface. In addition, the interface between the Mobility proxy and the MME can also be an interface similar to GS, (Gs like, simplified Gs interface, only transmitting LA update and paging messages).

For the convenience of description, two logical entities are defined: VMSC-R, VMSC-S, where: VMSC-R, that is, the registered VMSC (Visit Mobile Switching Center), the last LA update of the UE in the LTE network is This VMSC.

The VMSC-S, that is, the serving VMSC (Voice Call Service Visiting Mobile Switching Center), after the UE reselects to the 2G/3G cell, the voice call is established through the VMSC (Visit Mobile Switching Center) and acts as an anchor MSC (anchor MSC).

Whether the LTE network supports the network control The cell change of the UE (including the CS domain, including the CS domain unless otherwise specified) can be notified to the UE by broadcast system information or dedicated signaling. Through the broadcast system information notification method, cell changes of all UEs in the cell are controlled by the network. By means of dedicated signaling, such as handover messages, measurement control messages, cell change/update messages, paging messages, etc., it can be achieved that the cell change notifying the specific UE is controlled by the network.

In accordance with the above technical solutions, several specific embodiments are provided below to more clearly understand the above technical solutions.

Embodiment 1: In order to reduce the delay of the UE from reselecting the LTE cell to the 2G/3G cell and establishing a voice call, a method of triggering and updating the LA in the TA update process is adopted. Both scheme A and scheme B do not require a restricted mapping relationship between TA/TA list and LA. For scenario A, the implementation method is similar to the prior art. For scenario B, the LA update message is forwarded by the Mobility proxy between the MME and the MSC. From the perspective of the MSC, the BSS/RNS simulated by the Mobility proxy is included in the LA, and the update process of TA and LA is shown in FIG. 3.

When the TA update process is triggered, the UE determines whether to perform the LA update according to the trigger condition of the LA, and if the LA update is required in the process of the TA update. During the LA update process, the message exchange between the MME and the Mobility is through the S3, the interface, the interaction between the VMSC-R and the Mobility proxy through the simplified A/Iu interface (the interface only transmits the message of the LA update process and the voice call). Call the message).

Compared with the prior art, the advantage of the scheme B is that the modification of the existing 2G/3G standard specification is avoided due to the addition of the logic function Mobility proxy.

Embodiment 2: A UE camping in an LTE cell broadcasts a system message or a dedicated signaling The message is notified whether the voice call of the cell is transferred to the CS domain of the 2G/3G cell to establish a voice call. If yes, both the calling and the called voice call are transferred to the CS domain of the 2G/3G cell. As shown in FIG. 4( a ), the method for notifying the system information of the broadcast causes the voice calls of all UEs in the LTE cell to be transferred to the 2G/3G cell or not transferred.

As shown in FIG. 4 (b), a dedicated signaling manner, such as a handover message, a measurement control message, a cell change/update message, a paging message, etc., may be used to notify a specific UE to transfer a voice call to a CS domain of 2G/3G. Establish a voice call or not reselect.

Embodiment 3: The UE camps in the LTE cell, and the UE initiates a voice call of the calling party, according to an indication obtained by the system message or the dedicated signaling that was previously broadcasted, whether the voice call is established to the CS domain of the 2G/3G cell, Decide whether to transfer to a 2G/3G cell. The LTE-IDLE state UE establishes the calling voice call in the CS domain of the 2G/3G cell, as shown in FIG. 5, and specifically includes the steps:

51. The UE initiates a calling voice call in the LTE-IDLE state.

52. The previously broadcasted system message or dedicated signaling indicates that the voice call is to be established to the CS domain of the 2G/3G cell, the UE reselects to the 2G/3G cell, monitors the 2G/3G cell broadcast message and camps on the cell.

52a. If the LA of the camping cell triggers the normal LA update process, the normal LA update process is first performed.

53. The UE initiates a process of establishing a calling voice call in a CS domain of the 2G/3G cell.

Embodiment 4: Decide whether to reselect to a 2G/3G cell according to an indication obtained by a system message or dedicated signaling previously broadcasted whether the voice call is established to the CS domain of 2G/3G. Whether the LTE network supports network-controlled cell change (ie, NACC (Network-Assisted Cell Change) to GERAN (GSM/EDGE Radio Access Network GSM/EDGE Radio Access Network) and to UTRAN (Universal Terrestrial) Inter-RAT cell order of the Radio Access Network, the UE in the LTE-AC state establishes the calling voice call in the CS domain of the 2G/3G cell. The process is shown in Figure 6 and Figure 7, respectively.

Figure 6 shows a cell change in which the LTE network does not support network control, and the UE reselects to the 2G/3G cell to establish a calling voice call. Including steps:

61. When the UE is in the LTE-Active state, the UE initiates a calling voice call.

62. The previously broadcast system message or dedicated signaling indicates that the voice call is to be established to 2G/3G. The CS domain, and the UE learns that the LTE network does not support the network control cell change, the UE autonomously reselects to the 2G/3G cell, monitors the broadcast message of the 2G/3G cell and camps on the cell.

62a. If the LA of the camping cell triggers the normal LA update process, the normal LA update process is first performed.

63. The UE initiates a process of establishing a calling voice call in a CS domain of the 2G/3G cell.

Figure 7 shows the LTE network supporting the network control of the cell change. The LTE network commands the UE to reselect the 2G/3G cell to establish the calling voice call. Including steps:

71. The UE initiates a calling voice call in the LTE-AC state.

72. The previously broadcasted system information or dedicated signaling indicates that the voice call is to be established to the CS domain of 2G/3G, and the UE learns that the LTE network supports the cell change controlled by the network. The UE notifies the LTE network to initiate a calling voice call, and the LTE network commands the UE to reselect the 2G/3G cell, and carries the information of the target cell in the command message.

72a. If the LA of the target cell triggers the normal LA update process, the normal LA update process is performed first.

73. The UE initiates a process of establishing a calling voice call in a CS domain of the 2G/3G cell.

Embodiment 5: For the called voice call, whether or not to reselect to the 2G/3G cell is determined according to an indication obtained by the system message or the dedicated signal previously broadcasted whether the voice call is established to the CS domain of the 2G/3G cell. The paging message of the called voice call may be sent to the MME according to the foregoing scheme A: directly through the Gs like interface; or may be located in the foregoing scheme B: the paging message is first sent to the Mobility proxy through the simplified A/Iu interface, and then the Mobility The proxy then forwards it to the MME via the S3 'interface.

After the reselected 2G/3G cell, whether the VMSC-R and the VMSC-S are the same, the network side decides whether to adopt the MT roaming retry call method (called roaming retry technology). If they are the same, use the normal called procedure to establish a voice call. Otherwise, use the MT roaming retry call method or the B2B CS UA method (back-to-back CS proxy mode, which is introduced in the seventh embodiment) to establish a called voice call, as shown in Figure 8. Shown. FIG. 8 is a flowchart of establishing a called voice call by the UE autonomously reselecting to a 2G/3G cell. Specifically, the steps are as follows:

81. If, according to the scheme A, the VMSC-R sends a voice call paging message to the MME through the Gs-like interface. If according to scheme B, the paging message is sent to the MME through two steps 81a and 81b. 81a. According to scheme B, there is a corresponding TA/TA list and LA in each LTE cell, and the LA that performs location update to the VMSC-R through the Mobility proxy includes the Mobility proxy virtual BSS/RNS, and the VMSC-R passes The standardized way to update the used LAJ to send the paging to the UE, the paging message sending a voice call paging message to the Mobility proxy through the simplified A/Iu interface.

81b. According to scheme B, the Mobility proxy forwards the voice call paging message to the S3' interface to

MME.

82. The UE receives a voice call paging message from the network side.

83. According to the system message or the dedicated signaling previously broadcasted, the voice call is transferred to the CS domain of the 2G/3G, reselected to the 2G/3G cell, and the system message broadcasted by the cell is monitored and camped on the target cell.

84. If the LA of the target cell triggers the normal LA update process, the LA is updated. The updated LA belongs to the VMSC-R. In this case, the VMSC-R is the same as the VMSC-S. Go to step 85.

84a. If the LA of the target cell triggers a normal LA update process, the LA is updated. The updated LA belongs to the VMSC-S. In this case, the VMSC-R is different from the VMSC-S, and the process goes to step 85a.

85. The UE may send a paging corresponding message to the network side in the 2G/3G cell. The VMSC-R is the same as the VMSC-S, and the voice call is established in the CS domain of the 2G/3G cell using the normal called voice call procedure.

85a. The UE may send a paging corresponding message to the network side in the 2G/3G cell. VMSC-R is different from VMSC-S in that it is established in the CS domain of 2G/3G using the MT roaming retry call method or the B2B CS UA method (back-to-back circuit switched proxy mode, which is described in the seventh embodiment).

Embodiment 6: For a called voice call, it is decided whether to reselect to a 2G/3G cell based on an indication obtained by the previously broadcasted system information or a dedicated signal whether the voice call is established to the CS domain of the 2G/3G cell. Moreover, the LTE network indicates that it supports network controlled cell changes. After receiving the voice call paging message, the UE transfers to the 2G/3G cell by the network control, and then the called voice call is established in the CS domain of the 2G/3G cell.

After the reselected 2G/3G cell, whether the VMSC-R and the VMSC-S are the same, the network side decides whether to adopt the MT roaming retry call method or the B2B CS UA method. If they are the same, use the normal called procedure to establish a voice call, otherwise use the MT roaming retry call method or the B2B CS UA method to establish a called voice call, as shown in Figure 9. FIG. 9 is an LTE network control UE reselecting to a 2G/3G cell Establish a called voice call, including the steps:

91. According to scheme A, the VMSC-R sends a paging message of the voice call to the MME through the Gs like interface. If, according to scenario B, a paging message is sent to the MME through two steps 91a and 91b.

91a. According to the scheme B, the mapping relationship between the TA/TA list and the LA is configured in each LTE cell, and the LA that is updated by the Mobility proxy to the VMSC-R includes the Mobility proxy virtual

The BSS/RNS, the VMSC-R updates the used LAJ to send the paging to the UE in a standardized manner, and the paging message sends a voice call paging message to the Mobility proxy through the simplified A/Iu interface.

91b. According to the solution B, the Mobility proxy forwards the voice call paging message to the MME through the S3' interface.

92. The MME sends a paging message of the voice call to the eNB (evolved base station).

After the eNB parses the paging message and processes the packet, the eNB sends the message to the UE.

94. The voice call is to be established to the CS domain of the 2G/3G cell according to the system information or the dedicated signaling previously broadcasted, and the network supports the cell control of the network change. The eNB waits for the eNB to send a cell change command, and then the UE reselects to the 2G/3G cell designated by the network and camps on the target cell.

95. If the LA of the target cell triggers the normal LA update process, the LA is updated. The updated LA 3⁄4 is in the VMSC-R, in which case the VMSC-R is the same as the VMSC-S, and the process goes to step 96.

95a. If the LA of the target cell triggers the normal LA update process, the LA is updated. The updated LA belongs to the VMSC-S. In this case, the VMSC-R is different from the VMSC-S, and the process proceeds to step 96a.

96. The UE may send a paging corresponding message to the network side in the 2G/3G cell. The VMSC-R is the same as the VMSC-S, and the voice call is established in the CS domain of the 2G/3G cell using the normal called voice call procedure.

96a. The UE may send a paging corresponding message to the network side in the 2G/3G cell. Unlike VMSC-S, VMSC-R uses the MT roaming retry call method or the B2B CS UA method to establish the voice call in the CS domain of the 2G/3G cell.

Embodiment 7: For a called voice call, the UE decides whether to reselect to a 2G/3G cell according to an indication obtained by the previously broadcasted system information or dedicated signaling whether the voice call establishes a CS domain to the 2G/3G cell. The process of sending the called voice call paging message from the VMSC-R to the MME is the same as the UE in the LTE-IDLE state.

If the LTE network does not support network-controlled cell change, that is, to NACC (including system information for the CS domain, and the UE can perform network control in both LTE-IDLE and LTE-Active states) The cell in the LTE-active state is received by the UE in the LTE-Active state after receiving the called voice call paging message from the UE in the LTE-Active state. After the called voice calls the paging message, it is transferred to the 2G/3G cell by the network control, and then the called voice call is established in the CS domain of the 2G/3G cell, as shown in FIG.

After the reselected 2G/3G cell, whether the VMSC-R and the VMSC-S are the same, the network side decides whether to adopt the B2B CS UA technology. If they are the same, use the normal called process to establish a voice call, otherwise use the B2B CS UA technology to establish a called voice call. As shown in Figure 10. Figure 10 is a flowchart of the LTE network control of the VMSC-R as the back-to-back CS proxy mode. The UE reselects to the 2G/3G cell to establish a called voice call flow diagram, which specifically includes the steps:

101-104. The UE is currently in an LTE network, and the VMSC-R (ie, eMSC) serves the UE. When the UE is called, the GMSC (Gateway Mobile Switching Center) queries the HLR (Home Location Register) for information such as the MSRN (Mobile Station Roaming Number).

105. The GMSC sends an IAM (Initial Address Message) message to the VMSC-R according to the MSRN.

106. The VMSC sends a paging message to the UE through the LTE network.

107-109. After receiving the paging message, the UE indicates that the voice call is to be established to the CS domain of the 2G/3G cell according to the system information or the dedicated signaling that is previously broadcasted, and the network where the UE is located supports the cell control network change. Waiting for the cell change command sent by the eNB, after which the UE reselects to the network designated

The 2G/3G cell camps on the target cell.

The UE accesses the 2G/3G target cell to trigger the normal LA update process, and LA is updated, and the updated LA 3⁄4 is in the VMSC-R. If the VMSC-R is the same as the VMSC-S, the UE sends a paging response message to the network side in the 2G/3G cell, and establishes the voice call in the CS domain of the 2G/3G using the normal called voice call procedure.

If the VMSC-R is different from the VMSC-S, go to step 110.

110-112. After receiving the LAU (Location Area Update) update request message of the UE, the HLR sends a Cancel Location message to the VMSC-R, and the VMSC-R sends a corresponding Cancel Location ACK (Cancel Location Area Response message). Give the HLR. At the same time, the VMSC-R stops the paging timer.

113, 118-120, VMSC-R queries the HLR for information such as MSRN. 115. After the LAU update of the UE is successful, the HLR sends a PRN (Provide Roaming Number) query message to the VMSC-S.

114, 116-117, LAU process of the UE.

121. The VMSC-R obtains an MSAM message according to the query to send an IAM message to the VMSC-S.

122. The VMSC-S may need to wait for the LAU process to complete before the call process can be initiated.

123-125, the network and the UE perform the normal called process.

In the above method, if the GMSC (Gateway Mobile Switching Center;), the VMSC-R, and the VMSC-S support the BICC (Network Assisted Cell Change) protocol, the user plane of the UE's call can be directly from the GMSC to the VMSC-S.

In addition, the flow of the above method only gives a sequence of message flows that may be described, and is not limited to the flow of the above method in practice.

In addition, the above method is equally applicable to the following scenario of any network: The UE is processing the called process, and the network server that processes the called process changes. For example, the MSC changes due to a change in LA, and the call occurs abnormally.

The method for establishing a voice call back to the CS domain and the method for configuring the LA/TA list and the TA corresponding to the method for establishing a voice call back to the CS domain and the method for implementing the called flow are described in detail. The embodiment of the invention further provides a system for establishing a voice call back to the CS domain and a system for implementing the called process.

Figure 11 is a system for establishing a voice call back to the CS domain according to an embodiment of the present invention. Referring to the figure, the system includes:

The first indication unit 131 sends a first indication to the UE; the first indication unit sends a first indication that the UE voice call camping in the cell is established to the CS domain by using a system message broadcast by the cell; or by using a dedicated signaling message Transmitting a first indication that a UE camping within the cell establishes a voice call to the CS domain;

The reselecting unit 132 reselects the UE to the cell with the CS domain according to the first indication of the voice call setup;

The voice call establishing unit 133 is configured to establish the voice call by the UE in the CS domain of the cell.

Further, the system further includes a second indication unit 134, which provides support for establishing a voice call to A second indication of the network-controlled cell change of the cs domain.

a third indication receiving unit 135, configured to receive a third indication of establishing a voice call of the voice call paging message, where the paging message is from the network, or

Receiving a third indication that the UE initiates voice call setup.

As another system for establishing a voice call back to the CS domain provided by the embodiment of the present invention, referring to FIG. 12, the system includes:

The MSC 136 sends a voice call paging message to the logical function entity Mobility proxy 137 through the first interface;

The logical function entity Mobility proxy 137, the received voice call paging message is sent to the MME 138 through the second interface;

The MME 138, the voice call paging message is sent to the eNB 139;

The eNB 139 receives and parses and processes the paging message, and sends the paging message to the UE 140. Specifically, the method includes: if the network where the UE 140 camps indicates that the network control for establishing the voice call to the CS domain is changed, the eNB 139 Transmitting a cell change command according to the voice call paging message;

The UE 140 reselects to the cell having the CS domain according to the cell change command, and camps on the target cell.

The triggering update unit 141, the LA for the target cell triggers a normal LA update process, and performs LA update;

The UE 140 transmits a paging response message to the network side in the cell having the CS domain, and establishes the voice call in the CS domain of the cell having the CS domain.

The UE 140 establishes a called voice call by using the B2B CS UA method, or establishes a called voice call by using a B2B CS UA method (back-to-back CS proxy mode, which is introduced in Embodiment 7).

In order to better achieve the object of the present invention, an embodiment of the present invention further provides a system for implementing a called process. Referring to FIG. 13, the method includes:

The first network server 142 provides a service of the called session of the UE;

The second network server 143, in processing the called session, is configured to register the UE 144 with the network, and notify the first network server to cancel the registration information of the UE 144, and then initiate a called flow to the UE 144. . The called process is in a CS network, the first network server is an MSC mobile switching center, and the second network server is a home location server HLR. Or the home subscriber subscription server HSS.

The above method and system for implementing the called flow and the method for configuring the correspondence between the LA/TA list and the TA are not limited to the application of the present invention, and may be applied to other occasions.

The method, system, and network device for establishing a voice call back to the circuit switched domain are provided in detail in the foregoing embodiments of the present invention. For those skilled in the art, in accordance with the idea of the embodiment of the present invention, The scope of the present invention is not limited by the scope of the present invention.

Claims

Rights request

A method for establishing a voice call back to a circuit switched domain, the method comprising:

2. The method according to claim 1, wherein the network side sends an indication that the voice call is established to the circuit switched domain to the user terminal, and specifically includes:

The network side sends an indication that the voice call is established to the circuit switched domain to the user terminal by using a system message broadcast by the cell; or

The network side sends an indication to the user terminal to establish a voice call to the circuit switched domain through a dedicated signaling message.

The method of claim 1, wherein before the establishing a voice call in the circuit switched domain of the cell, the method further includes:

The network side sends an indication to the user terminal to support a cell change controlled by the network.

The method according to claim 3, wherein the network side sends an indication to the user terminal to support a cell change controlled by the network, which specifically includes:

Sending, by the network side, a system message broadcasted by the cell, to the user terminal, an indication of a cell change supporting network control; or

The network side sends an indication of the cell change supporting the network control to the user terminal by using a dedicated signaling message.

The method of claim 1 or 4, wherein the user terminal initiates a voice call according to the indication, including:

The network side receives an indication of voice call establishment sent by the user terminal.

The method according to claim 1, wherein before the user terminal initiates a voice call, the method includes:

The network side receives an indication of voice call establishment, and sends an indication of the voice call establishment to the user terminal; the indication is a paging message of a voice call.

7. The method of claim 1 wherein said reselecting to have a circuit switched domain The specific area includes:

The user terminal autonomously reselects to a cell having a circuit switched domain; or

Receiving, by the network side, an indication of voice call establishment sent by the user terminal, and sending a cell reselection command to the user terminal according to the indication of the voice call establishment, to command the user terminal to reselect to have a circuit switched domain Community.

8. The method according to claim 1, wherein the network comprises a system architecture evolution network or a long term evolution network; and the cell with the circuit switched domain is a 2G/3G cell.

The method according to claim 1, wherein after the reselecting to the cell having the circuit switched domain, the method further includes:

The user terminal establishes a called voice call by using a called roaming retry method.

A method for establishing a voice call back to a circuit switched domain, the method comprising: the evolved node receiving a voice call paging message sent by the mobile switching center by using a preset logical function entity and a mobility management entity;

The method according to claim 10, wherein a first interface is provided between the mobile switching center and a preset logical function entity, and the first interface is an A/Iu interface or a transmission only location. Simplified A/Iu interface for zone update and paging messages;

A second interface is provided between the preset logical function entity and the mobility management entity, and the second interface is a Gs/S3 interface or a simplified Gs/S3 interface that only transmits LA update and paging messages.

The method according to claim 10 or 11, wherein, after the reselecting the target cell with the circuit switched domain according to the cell change command, the method further includes:

The location area of the target cell triggers a normal location area update process, and the location area is updated; the user terminal sends a paging response message to the network side in the cell with the circuit switched domain.

The method according to claim 12, wherein the location area of the target cell triggers a normal location area update process, including: The logical function entity forwards a location area update message between the mobile switching center and the mobility management entity.

The method of claim 13, wherein the establishing a voice call in the circuit switched domain of the target cell includes:

The user terminal establishes a called voice call by using a called roaming retry method; or

The user terminal establishes a called voice call using a back-to-back circuit switched proxy method.

The method according to claim 14, wherein the using the back-to-back circuit switching proxy method to establish a called voice call includes:

The user terminal establishes a called session flow in a network where the circuit switched domain is located through the mobile switching center;

In processing the called session, the user terminal registers with the network side through a home location server or a home subscriber subscription server;

And the home location server or the home subscriber subscription server notifies the mobile switching center to cancel the registration information of the user terminal;

The home location server or the home subscriber subscription server initiates a call flow to the user terminal.

16. A system for backing up a circuit call to establish a voice call in a circuit switched domain, comprising: a network side, configured to send, to a user terminal, an indication to establish a voice call to a circuit switched domain; the indication is used to indicate the The user terminal initiates a voice call based on the indication and reselects to the cell having the circuit switched domain and establishes a voice call in the circuit switched domain of the cell.

The system according to claim 16, wherein the network side is configured to send, by using a system message broadcast by the cell, an indication that the voice call is established to the circuit switched domain; or

An indication for establishing a voice call to a circuit switched domain by a dedicated signaling message.

18. The system of claim 17, wherein the network side is further configured to issue an indication of a network controlled cell change that supports establishing a voice call to the circuit switched domain.

The system according to claim 18, wherein the network side is further configured to receive an indication for establishing a voice call, where the indication is a paging message of a voice call; or

It is used to receive an indication that the user terminal initiates the establishment of the calling voice call.

The system according to any one of claims 16 to 19, wherein the network package Including system architecture evolution network or long-term evolution network.

21. A system for backing up to a circuit switched domain to establish a voice call, comprising: an evolved node, configured to:

The system according to claim 21, wherein a first interface is provided between the mobile switching center and a preset logical function entity, and the first interface is an A/Iu interface or a transmission only location. Simplified A/Iu interface for zone update and paging messages;

The system of claim 21 or 22, further comprising:

The triggering update unit is configured to update the location area when the location area of the target cell triggers the normal location area update process.