WO2010133179A1

WO2010133179A1 - Switching method, apparatus and system for realizing circuit switching (cs)

Info

Publication number: WO2010133179A1
Application number: PCT/CN2010/073035
Authority: WO
Inventors: 许亮; 胡小群; 潘颖欣; 翁武林; 杨景军
Original assignee: 华为技术有限公司
Priority date: 2009-05-21
Filing date: 2010-05-21
Publication date: 2010-11-25
Also published as: CN101895946A

Abstract

A switching method for realizing circuit switching (CS) is provided. The method includes: a source controller initiates a switching preparation procedure to a target controller via the interconnected interface between the controllers; a response message is received from the target controller after completing the reservation of the resource; the source controller sends a switching command to the terminal according to the received response message from the target controller. The solution can reduce the delay of the switching and reduce the call-drop rate due to the long preparation time of the switching. At the same time, the signaling and data after the switching can be ensured to transmit normally due to the reestablishment of the data transmission link.

Description

The present invention claims the priority of the Chinese patent application filed on May 21, 2009, the Chinese Patent Office, the application number is 200910203423.2, and the invention is entitled "Implementation of Circuit Switching CS Switching Method and System". The entire contents of which are incorporated herein by reference. Technical field

The present invention relates to the field of communications, and more particularly to a circuit switching CS switching method, apparatus and system. Background technique

Circuit switching (CS) refers to the process of establishing connections as needed and allowing them to be dedicated until they are released. A circuit-switched network consists of a physical path and supports a single connection between two endpoints during a network connection. Circuit switched networks are typically used when transmitting real-time data (such as audio and video, etc.) or when quality of service (Q0S) requirements are high. For example, traditional voice telephony services are the process of circuit switching through the Public Switched Telephone Network (PSTN).

In a mobile communication system, a circuit switched manner is generally used to carry voice. The mobile communication system currently includes a GSM system, a UMTS system, an LTE system, a CDMA system, etc. In order to support seamless user roaming, the mobile communication system provides a circuit switched handover (ie, CS handover) function, and the CS handover can be in the same type. The internal network of the system can also be carried out between different standard networks. For example, in the existing network, there are multiple types of networks (such as 2G GSM/3G WCDMA, TDSCDMA, CDMA2000, etc.), which can be CS handover between GSM and UMTS, and CS handover in GSM. Switching can be based on coverage for CS switching, or CS switching based on traffic, CS switching based on load, and so on.

The GSM system belongs to the 2G system; the UMTS belongs to the 3G system, including WCDMA, TD-SCDMA, and the like. The following is an example of a CS handover from a 3G TD-SCDMA system to a 2G GSM system, and introduces a prior art handover procedure. Referring to Figure 1, the prior art CS switching process from 3G to 2G includes the following steps:

S 101 : Source Radio Network Controller (SRNC) in TD-SCDMA decides to perform GSM Inter-system switching, sending a request message RELOCATION REQUIRED to the 3G CN through the Iu interface;

SI 02 : 3G CN sends a preparation switch message of the MAP layer to the GSM MSC PREPARE HANDOVER;

SI 03: The GSM MSC sends a HANDOVER REQUEST message to the BSC to initiate a handover preparation process;

S104: The BSC performs handover preparation, reserves resources, and sends a HANDOVER REQUEST ACK message to the 3G CN after completion;

S105: The GSM MSC and the BSS complete the handover preparation, and the MSC returns a MAP/E preparation handover response message to the 3G CN PREPARE HANDOVER RESPONSE;

S106: The 3G CN sends a RANAP migration command message RELOCATION COMMAND to the SRNC, as a response to the SRNC initial request.

S107: The SRNC sends a handover UTRAN command to cancel the HANDOVER FROM UTRAN COMMAND to the UE through the existing RRC connection, and commands the UE to perform inter-system handover.

Steps S101 to S106 are all CS handover preparation phases, including a signaling flow of the A interface (ie, between the target MSC and the BSC) and a resource reservation process; S107 is a handover execution phase, and the SRNC is officially sent to the UE for handover. The command. In the prior art, a long switching preparation time is required, and the switching efficiency is low. Moreover, in some scenarios, long-term handover preparation may affect the normal transmission of data. Summary of the invention

In view of this, the embodiments of the present invention provide a circuit switching CS switching method, device, and system, to reduce handover delay and improve handover efficiency.

An aspect of the present invention provides a method for implementing circuit switched CS switching, including:

The source controller initiates a handover preparation process to the target controller by using an inter-controller interconnection interface; and receiving, by the inter-controller interconnection interface, a response message after the target controller completes the reserved resource;

The source controller sends a handover command to the terminal according to the received response message of the target controller. Another aspect of the present invention provides a method for implementing circuit-switched CS handover, including: a target controller responding to a handover preparation process initiated by a source controller through an inter-controller interface, and reserving resources for handover;

After the target controller reserves resources for handover, it returns a response message to the source controller.

Another aspect of the present invention provides an apparatus for implementing circuit switched CS switching, located at a source controller, including:

The switching preparation process initiating unit is configured to initiate a switching preparation process to the target controller by using an inter-controller interconnection interface;

The response message receiving unit is configured to receive, after the target controller completes the reserved resource, a response cancellation command sending unit, configured to send a handover command to the terminal according to the received response message of the target controller.

Another aspect of the present invention provides an apparatus for implementing circuit-switched CS switching, located at a target controller, including:

a resource reservation unit, configured to respond to a handover preparation process initiated by the source controller through the inter-controller interface, and reserve resources for the handover;

And a message sending unit, configured to return a response message to the source controller after the resource is reserved for the handover. Another aspect of the present invention also provides a communication system comprising a first implemented circuit switched CS switch at a source controller and a second implemented circuit switched CS switch at a target controller.

Through the above solution, the time for handover preparation can be shortened, thereby reducing the handover delay, and P is low in probability of causing a phenomenon such as dropped calls due to excessive handover preparation time. DRAWINGS

1 is a flow chart of a CS switching in the prior art;

2 is a flowchart of a first CS handover method according to an embodiment of the present invention;

3 is a flowchart of a second CS switching method according to an embodiment of the present invention;

4 is a schematic structural diagram of a CS switching first network system according to an embodiment of the present invention;

FIG. 5 is a flowchart of a third CS handover method according to an embodiment of the present invention;

6 is a schematic structural diagram of a CS switching second network system according to an embodiment of the present invention;

FIG. 7 is a flowchart of a fourth CS handover method according to an embodiment of the present invention; FIG. 8 is a schematic diagram of a third network architecture of a CS handover according to an embodiment of the present invention; FIG. 9 is a flowchart of a fifth CS handover method according to an embodiment of the present invention;

10 is a schematic structural diagram of a CS switching fourth network system according to an embodiment of the present invention;

FIG. 11 is a flowchart of a sixth CS handover method according to an embodiment of the present invention;

FIG. 12 is a schematic diagram of a CS switching apparatus according to an embodiment of the present invention; FIG.

FIG. 13 is a schematic diagram of another CS switching apparatus according to an embodiment of the present invention.

The present invention will be further described in detail with reference to the drawings and specific embodiments. Referring to FIG. 2, a method for implementing circuit-switched CS switching according to an embodiment of the present invention may be as follows.

201: The source controller initiates a handover preparation process to the target controller through the inter-controller interconnection interface. For example, the source controller may send an enhanced handover request message to the target controller to notify the target controller to reserve resources for the call currently being handed over, and return an enhanced handover response after the reservation is completed.

In another embodiment of the present invention, the source controller can monitor the current call and determine whether a CS handover is required (for example, the determination can be made according to the measurement report reported by the terminal). If it is determined that the current call of the terminal needs to be CS-switched, the source controller selects a suitable target cell for the call, and sends an enhanced handover request message to the controller (ie, the target controller) to which the target cell belongs. The current call may be a voice service or a circuit domain data (CSD, Circuit t Swi t ched Da ta) service. The following describes voice as an example. In another embodiment of the present invention, the source controller needs to establish a transmission connection on the inter-controller interface between the source controller and the target controller before transmitting the enhanced handover request message for control plane signaling transmission. And/or user plane data transmission, which can be Connected on or ented or Connected ions.

For example, the enhanced handover request message can be controlled between the source controller and the target controller. The inter-machine interconnect interface sends the message to the target controller. In another embodiment of the present invention, the enhanced handover request message may include the source cell identifier (such as CGI, RNC-ID, and Cel ID, etc.), and the target cell identifier (such as CGI, RNC-ID, and Cel l ID, etc., source controller identity (such as RNC-ID, etc.), target controller identity, call identity, terminal identity (such as IMSI, TMSI, etc.), channel type, voice codec (such as AMR 12. HR, FR, etc.), terminal support capabilities (such as Classmark 1, Classmark 2, Classmark 3, etc.), user plane information, transport layer information (such as transport layer address and binding Id), voice version information, etc. Or all. After receiving the message, the target controller may allocate resources for the current call, including allocating appropriate radio channel resources according to information such as the current codec codec information and the terminal's support capability. After the resource allocation is completed, the device may pass the The inter-controller interconnect interface returns a response message to the source controller. The enhanced handover response message carries handover related information, such as target cell description information, allocated radio resource information, and the like.

The source controller refers to a controller where the terminal is located before the handover, and the target controller refers to a controller where the terminal is located after the handover.

S202: After receiving the response message of the target controller, the source controller sends a command for performing CS handover to the terminal, and establishes a transmission between the source controller and the source MSC and the inter-controller interface. The connection between the user plane data and/or the control plane signaling link of the core network before and after the handover is maintained.

For example, after receiving the response message, the source controller may send a command for performing CS handover to the terminal. After receiving the CS handover command, the terminal directly switches to the target cell under the target controller.

In the method provided by the embodiment of the present invention, the enhanced handover request message is sent to the target controller through the inter-controller interface, and the target controller may reserve resources for the current call, but does not control the source controller or the target. The MSC where the device is located sends a message. Therefore, during the entire handover process and after the handover, the source controller and the MSC where the target controller is located do not participate. That is, the MSC where the source controller is located does not know that the terminal is switched out, and the target controller is located. The MSC is also unaware that there is a terminal handover, and thus cannot provide an interface function for the target controller. .

Therefore, when the method adopted by the embodiment of the present invention first notifies the target controller to reserve resources, Establishing a connection relationship between the transmission of the target controller to the target base station and the inter-controller interface transmission; and then establishing, by the source controller, the transmission of the source controller to the source MSC and the inter-controller interface The connection between transmissions. Therefore, the network entity participating in the data transmission after the handover will include: the target cell, the target controller, the source controller, and the source MSC.

That is, in the embodiment of the present invention, the source controller needs to establish a transmission connection of the inter-controller interface; when the source controller sends the handover command to the terminal, the source controller needs to establish the transmission from the source controller to the source MSC. The connection between the inter-controller interface transmissions is used for control plane signaling transmission and/or user plane data transmission. Before the target controller sends the enhanced handover response message, it needs to allocate the transmission connection between the target controller and the target cell, and establish a connection relationship between the transmission between the target controller and the target cell and the interconnection between the interfaces of the controller. User plane data and/or control plane signaling transmission is performed after handover. The user plane and/or control plane link on the inter-controller interface of each call is identified on the source controller and the target controller, such as the transport layer address (IP address, UDP port number) that can be source controller And the transport layer address (IP address, UDP port number) of the target controller.

It can be seen that, in the embodiment of the present invention, the process of sending a handover request to the MSC where the target controller is located is omitted, so that the time for handover preparation can be shortened, thereby reducing the handover delay, and P is low because the handover preparation time is too long. The probability of a phenomenon such as words.

In the above switching process, the core network does not perceive that a handover has occurred, and considers that the current call is under the source controller. Therefore, after completing one handover, if the terminal still needs to continue to switch, the terminal switches from the source cell to the source cell. After a target cell, it needs to be switched to another new target cell. If the new target cell and the previous target cell are under the same controller, the controller can perform intra-controller handover, and the notification is notified after the handover. The source controller; if the new target cell and the previous target cell are under different controllers, the switch to the new target controller may be initiated by the controller where the previous target cell is located. For example, after the terminal switches from one cell of the 3G WCDMA or TD-SCDMA network to one cell of the 2G GSM network, it may continue to move, and needs to switch to another GSM cell, and continuous handover occurs if the two GSMs If the cell is under the same controller, the controller performs intra-controller handover; if the two GSM cells are under different controllers, the switch can be initiated by the controller of the switched cell. The switching process of the controller avoids the impact on the core network. The cs handover method provided by the embodiment of the present invention can be applied to handover within the same network (for example, switching in 2G GSM or 3G TD-SCDMA, WCDMA network), and can also be applied to handover between different networks (for example, Switching from 3G TD-SCDMA, WCDMA to 2G GSM, or switching from 2G GSM to 3G TD-SCDMA, WCDMA) ₀ When switching within 2G network, the source controller is in 2G GSM network The BSC, the target controller is another BSC in the 2G GSM network; when switching within the 3G network, the source controller is a 3G TD-SCDMA or an RNC in a WCDMA network, and the target controller is Another RNC in a 3G TD-SCDMA or WCDMA network; when switching from a 3G TD-SCDMA or WCDMA network to a 2G GSM network, the source controller is a 3G TD-SCDMA or RNC in a WCDMA network, The target controller is a BSC in a 2G GSM network; when switching from a 2G network to a 3G network, the source controller is a BSC in a 2G GSM network, and the target controller is 3G TD-SCDMA or RNC in a WCDMA network. When switching between different networks, it may be necessary to convert the signaling message format. For example, when switching from a 3G TD-SCDMA or WCDMA network to a 2G GSM network, the network entities performing data transmission are 3G MSC, RNC, BSC, BTS, and 3G MSC, RNC are entities in the 3G network, BSC, The BTS is an entity in a 2G network. The format of the signaling message is different in different networks. In the normal case, the uplink signaling of the BSC needs to be transmitted to the 2G MSC through the A interface. In the embodiment of the present invention, the inter-controller interface and the Iu-CS interface are required. The interface between the 3G MSC and the RNC is transmitted to the 3G MSC. Therefore, in order to enable the correct transmission of the message, the conversion of the A interface and the Iu-CS interface signaling message format is required. The conversion can be done on the source controller or the target controller, such as in an enhanced handover request message and/or an enhanced handover response message.

In addition, since the voice codec type may be different before and after the handover, the voice codec type of the target network (that is, the network where the target controller is located) and the source network (that is, the network where the source controller is located) are also required. ) Adaptation, conversion of speech codec types. The adaptation process can be performed on the source controller or the target controller, such as in an enhanced handover request message and/or an enhanced handover response message.

In order to better understand the method provided by the embodiments of the present invention, the following detailed description will be made by way of specific examples.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 1. Referring to FIG. 3, in this example, a terminal needs to be TD-SCDMA from 3G. The network is switched to a cell in the 2G GSM network, the source controller is the RNC, and the target controller is the BSC. The method may be as follows:

S301: When the RNC decides (such as according to the measurement report reported by the terminal) that the call of a terminal needs to be switched from the TD-SCDMA cell to the GSM cell, the enhanced handover request message (such as ENHANCED RELOCATION REQUEST) is sent through the inter-controller interface. Go to the BSC; and wait for the BSC's response.

The enhanced handover request message may include, but is not limited to, a source cell identifier (such as CGI, RNC-ID, and Cell ID, etc.), a target cell identifier (such as CGI, RNC-ID, and Cel ID, etc.), and a source controller. Identification (such as RNC-ID, etc.), target controller identity, current call identity, current terminal identity (eg IMSI, TMSI, etc.), channel type, voice codec (eg AMR 12. 2, HR, FR, etc.), terminal Some or all of the support capabilities (such as Clas smark 1, Clas smark 2, Clas smark 3, etc.), user plane information, transport layer information (such as transport layer address and binding Id), voice version information, and so on.

S302: After receiving the enhanced handover request message, the BSC reserves resources for the call, and then returns an enhanced handover response message (such as ENHANCED RELOCATION RESPONSE) message to the RNC through the inter-controller interconnection interface. For example, the enhanced handover response message may include, but is not limited to, a cell description (such as Cel Descr ipt ion, etc.), a radio channel description, a handover reference (such as a Handover Reference, etc.), and a codec (such as AMR 5. 9, FR, HR). Part or all of information such as EFR, hopping information, encrypted information, and transport layer information (including transport layer addresses and binding Ids). In another embodiment of the present invention, before transmitting the enhanced handover response message, the BSC needs to allocate channel resources for the terminal, establish a bearer of the inter-controller interface between the RNC and the BSC, and establish an Abi s port and control for the channel. The transmission connection of the inter-device interconnection interface (for example, the Abis transmission connection of the BSC and the base station where the target cell is located needs to be allocated, establishing a connection relationship between the inter-controller interface transmission between the RNC and the BSC and the Abi s port transmission, for switching User plane data and/or control plane signaling transmissions are then performed.

S303: The RNC constructs a handover UTRAN command HANDOVER FROM UTRAN COMMAND message according to the content of the enhanced handover response message, and sends the message to the terminal; the RNC is responsible for establishing a connection between the Iu-CS interface of the call and the transmission between the inter-controller interface interfaces. Used for user plane after switching Transmission of data and/or control plane signaling.

The Iu-CS port transmission of the call is a transmission between the RNC and the 3G MSC. In the foregoing process, the Iu-CS user plane data link and the control plane signaling link corresponding to the call may remain unchanged. change.

S304: The terminal performs handover, and after the GSM cell access succeeds, sends a handover complete message (for example, HANDOVER COMPLETE); at this time, the terminal switches to the GSM cell;

After receiving the handover command, the terminal performs access to the target GSM cell, and sends a HANDOVER ACCESS message. The BSC receives the HANDOVER ACCESS and detects that the terminal accesses the air interface, and sends an enhanced handover detection ENHANCED REL0CAT to the RNC. The message, after receiving the message, the RNC converts the connection of the user plane to the BSC.

S305: The BSC sends an enhanced handover to the RNC through the inter-controller interface to complete the ENHANCED RELOCATION COMPLETE message, and informs the RNC to release related resources, such as the lub bearer link and the air interface resource of the call; the RNC starts data/signaling between the controllers. Transceiver of the interconnect interface.

S306: After the handover is completed, user plane data and/or control plane signaling between the terminal and the 3G MSC are transmitted through the inter-controller interface and the Iu-CS interface. Since the terminal is in the GSM network at this time, the signaling of transmission and reception needs to be in the format of the GSM system, so the BSC or RNC needs to perform the conversion of the GSM and TD-SCDMA signaling formats.

In addition, the RNC or BSC may need to add a Transcoder and Rate Adapter Uni t (TRAU) to complete the voice codec type in the 2G network (such as GSM) to the 3G network (such as TD-SCDMA). ) Adaptation and conversion of speech codec types. For example: Originally, AMR codec is used in TD-SCDMA, and FR, EFR or HR codec is used in GSM after handover. The codec conversion and rate adaptation unit needs to complete the corresponding codec conversion; The AMR coding rate needs rate adaptation and rate adjustment. When the inter-controller interface uses IP to transmit user plane data, RTP can be used for voice data transmission. The TRAU also needs to perform RTP packet group. Package, unpacking processing.

FIG. 4 shows a schematic diagram of the network architecture when switching from a 3G network to a 2G network. The direction of the arrow is the flow of the message during the handover preparation process, and the entities connected by the dotted line represent the network entity used for the data transmission after the handover. After switching from 3G to 2G, if it is found that the handover needs to be continued, the handover can be continued in various ways.

Method 1, refer to Figure 5, including:

S501: The SBSC (the source BSC, that is, the BSC where the terminal is currently located, the previous terminal is switched from the 3G to the current SBSC) (if according to the measurement report reported by the terminal), the terminal needs to continue to switch to another controller. The target cell initiates a handover preparation process by using an inter-controller interface between the SBSC and the RNC, such as sending a first enhanced handover request message to the RNC, requesting handover to a target cell on another controller, which may be a 3G cell or a 2G cell. . For example, if the target cell is a 2G GSM cell, the controller is the target BSC (DBSC);

The first enhanced handover request message may include, but is not limited to, a source cell identifier (such as CGI, RNC-ID, and Cel ID, etc.), a target cell identifier (such as CGI, RNC-ID, and Cel 1 ID, etc.), and a source controller identifier. (such as BSC-ID, etc.), target controller identity, current call identity, current terminal identity (such as IMSI, TMSI, etc.), channel type, voice codec (such as AMR 12. 2, HR, FR, etc.), terminal Some or all of the support capabilities (such as Clas smark 1, Clas smark 2, Clas smark 3, etc.), user plane information, transport layer information (such as transport layer address and binding Id), voice version information, and so on.

S502: After receiving the first enhanced handover request message of the SBSC, if the RNC has an inter-controller interconnection interface between the RNC and the DBSC, send a second enhanced handover request message to the DBSC through the inter-controller interconnection interface; and wait for the DBSC the response to.

The second enhanced handover request message may include, but is not limited to, a source cell identifier (such as CGI, RNC-ID, and Cel ID, etc.), a target cell identifier (such as CGI, RNC-ID, and Cel 1 ID, etc.), and a source controller identifier. (such as RNC-ID, etc.), target controller identity, current call identity, current terminal identity (such as IMSI, TMSI, etc.), channel type, voice codec (such as AMR 12. 2, HR, FR, etc.), terminal Some or all of the support capabilities (such as Clas smark 1, Clas smark 2, Clas smark 3, etc.), user plane information, transport layer information (such as transport layer address and binding Id), voice version information, and so on.

S503: After receiving the second enhanced handover request message, the DBSC reserves resources for the call, and returns a second enhanced handover response message to the RNC through the inter-controller interconnection interface. The second enhanced handover response message may include a cell description (such as Cel Descr ipt ion, etc.), a radio channel description, a handover reference (such as a Handover Reference, etc.), and a codec (such as AMR 5. 9, FR, HR, EFR, etc.) Part or all of the information such as frequency hopping information, encrypted information, and transport layer information (including transport layer addresses and binding Ids).

Before sending the second enhanced handover response message, the DBSC needs to allocate channel resources to the terminal, establish a bearer between the inter-controller interface between the RNC and the DBSC, and establish a transmission connection between the DBSC Abi s interface and the inter-controller interface for the channel. (For example, it is required to allocate the ABS connection of the DBSC and the base station where the target cell is located, establish a connection relationship between the transmission between the inter-controller interface between the RNC and the DBSC, and the Abi port transmission, and perform user plane data after the handover. And/or transmission of control plane signaling).

S504: The RNC sends a second enhanced handover response message to the SBSC, where the DBSC switching command is included.

S505: The SBSC constructs a handover command (HANDOVER COMMAND) message according to the second enhanced handover response message content, and sends the message to the terminal.

S506: After the terminal switches to the target cell of the DBSC according to the handover command, the terminal sends a handover completion message to the DBSC. HANDOVER COMPLETE;

After receiving the handover command, the terminal performs access to the target GSM cell, and sends a handover access HANDOVER ACCESS message. The DBSC receives the HANDOVER ACCESS and detects that the terminal accesses the air interface, and sends an enhanced handover detection ENHANCED RELOCAT I ON DETECT message to the RNC. After receiving the message, the RNC converts the connection of the user plane to the DBSC.

S507: DBSC sends an enhanced switch to the RNC through the inter-controller interface. The ENHANCED RELOCATION COMPLETE message is sent to inform the RNC that the terminal has switched to DBSC.

S508: The RNC sends a clear command CLEAR COMMAND to the SBSC, so that the SBSC releases related resources of the current terminal/call, such as Abi s interface signaling and user plane connection of the call, signaling and user of the inter-controller interface between the RNC and the SBSC. Face connection, air interface resources; RNC starts data transmission/signaling between the RNC and the DBSC.

S509: The SBSC returns a clear response after completing the resource release; S510: After the handover is completed, the user plane data and/or control plane signaling between the terminal and the 3G MSC passes through the Abis port of the DBSC, the inter-controller interface between the RNC and the DBSC, and the Iu-CS interface of the RNC and the 3G MSC. Transfer. Since the terminal is in the GSM network at this time, the signaling of the transmission and reception needs to be in the format of the GSM system, so the DBSC or the RNC may need to perform the conversion of the GSM and TD-SCDMA signaling formats.

In addition, RNC or DBSC may need to add TRAU (Transcoder and Rate Adapter Uni t) to complete the adaptation of the speech codec type used in the 2G network (such as GSM) to the voice codec type used on the Iu-CS interface. , conversion.

FIG. 6 is a schematic diagram showing the network architecture when switching from the 3G network to the 2G network and continuing to switch to another BSC in the first mode. The direction of the arrow is the flow of the message during the preparation of the handover, and the entities connected by the dotted line represent the network entity used for the data transmission after the handover.

Method 2, see Figure 7, including the following steps:

S701: The SBSC (the source BSC, that is, the BSC where the terminal is currently located, the previous terminal is switched from the 3G to the current SBSC) sends an enhanced handover request message to the RNC through the inter-controller interface between the SBSC and the RNC, requesting to switch to The target cell on the other controller may be a 3G cell or a 2G cell, for example, the target cell is a 2G cell, and the controller where the target cell is located is the target BSC (DBSC); the enhanced handover request message may include but is not limited to the source cell. Identification (such as CGI, RNC-ID, and Cel l ID, etc.), target cell ID (such as CGI, RNC-ID, and Cel ID, etc.), source controller ID (such as RNC-ID, etc.), target controller ID, current The identity of the call, the current terminal identity (such as IMSI, TMSI, etc.), channel type, voice codec (such as AMR 12. 2, HR, FR, etc.), terminal support capabilities (such as Clas smark 1, Clas smark 2, Clas smark Part or all of information such as user plane information, transport layer information (such as transport layer address and binding Id), voice version information, and so on.

S702: After receiving the enhanced handover request message of the SBSC, the RNC, if there is no inter-controller interface between the RNC and the DBSC, initiates an Iu-CS interface of the RNC and the 3G MSC through the access network-core network interface. The handover preparation process, such as sending a handover request message Relocat ion Requi red message, initiates a handover procedure to the 2G cell, and waits for a response of the 3G MSC;

The RNC sends a handover request message RELOCATION REQUIRED to the 3G MSC through the Iu interface; the 3G MSC sends a handover preparation message PREPARE HANDOVER to the 2G MSC; the 2G MSC allocates a resource for the handover, and sends a handover request message HANDOVER REQUEST to the DBSC; the DBSC allocates channel resources, For The terminal establishes a bearer with the A port of the 2G MSC, and returns a handover response message to the 3G MSC through the 2G MSC. HANDOVER REQUEST ACKNOWLEDGE ₀ 3G The MSC sends a handover command RELOCATION COMMAND ₀ to the RNC.

S703-S704: The RNC receives the RELOCATION COMMAND message of the 3G MSC, that is, the handover preparation is completed, and the enhanced handover command message ENHANCED RELOCATION COMMAND is sent to the SBSC through the inter-controller interconnection interface between the SBSC and the RNC, and the message includes the DBSC handover. command;

S705: The SBSC receives the ENHANCED RELOCATION COMMAND message, prepares a handover command, and sends the command to the terminal to switch to the target cell.

S706: After switching to the target cell of the DBSC according to the handover command, the terminal sends a handover complete message Handover Complete to the DBSC; the DBSC returns a handover success message HANDOVER COMPLETE ₀ to the CN

S707: The RNC receives the Iu release command of the 3G MSC. The Iu RELEASE COMMAND ₀ receives the message, and the RNC notifies the SBSC to release the resource for the currently switched call through the inter-controller interconnection interface.

S708: After the SBSC completes the resource release, the response is returned to the RNC, and then the RNC returns the Iu release completion message. The Iu RELEASE COMPLETE responds to the 3G MSC.

S709: After the handover is completed, user plane data and/or control plane signaling between the terminal and the 2G MSC are transmitted through the Abs and A interfaces of the DBSC.

FIG. 8 is a schematic diagram showing the network architecture of the second mode after switching from the 3G network to the 2G network and continuing to switch to another BSC. The direction of the arrow is the flow of the message during the preparation of the handover, and the entities connected by the dotted line represent the network entity used for the data transmission after the handover.

Method 3, see Figure 9, including the following steps:

S901: SBSC (source BSC, that is, the BSC where the terminal is currently located, the previous terminal is switched from 3G to the current SBSC) sends an enhanced handover request message to the DBSC through the inter-controller interconnection interface between the SBSC and the DBSC, requesting to switch to Target cell on the DBSC;

The enhanced handover request message may include, but is not limited to, a source cell identifier (such as CGI, RNC-ID, and Cel ID, etc.), a target cell identifier (such as CGI, RNC-ID, and Cel ID, etc.), and a source controller identifier. (such as BSC-ID, etc.), target controller ID, current call identifier, current terminal identifier (such as IMS I, TMS I, etc.), channel type, voice codec (such as AMR 12. 2, HR, FR, etc.), Part or all of the terminal's support capabilities (such as Clas smark 1, Clas smark 2, Clas smark 3, etc.), user plane information, transport layer information (including transport layer address and binding Id), voice version information, and so on.

S902: After receiving the enhanced handover request message, the DBSC allocates a radio channel resource for the call, allocates an Ab is port transmission connection between the DBSC and the base station where the target cell is located, and then returns an enhancement to the SBSC through the inter-controller interconnection interface. Type switching response message;

The enhanced handover response message may include a cell description (such as Ce ll Descr i pt i on, etc.), a radio channel description, a handover reference (such as a Handover Reference, etc.), and a codec (such as AMR 5. 9, FR, HR, EFR, etc.) Part or all of the information such as frequency hopping information, encrypted information, and transport layer information (including transport layer addresses and binding Ids).

Before transmitting the enhanced handover response message, the Abis interface of the base station where the BSC and the target cell are located needs to be established. If the inter-controller interface transmission between the RNC and the BSC has been established before, the inter-controller interface transmission and the inter-controller need to be established. The connection between the Abs port transmissions is used for the transmission of the user plane data and/or the control plane signaling after the handover.

S903: After receiving the enhanced handover response message, the SBSC constructs a handover command message HANDOVER COMMAND according to the message content, and sends the message to the terminal. The connection between the SBSC and the inter-DBSC interconnection interface transmission and the interconnection between the SBCS and the RNC is required. .

S904: After the terminal switches to the target cell of the DBSC according to the handover command, the terminal sends a handover completion message to the DBSC, HANDOVER C0MLPLETE;

The DBSC sends a clear command through the inter-controller interface to notify the SBSC to release the resources for the currently switched call. After the SBSC completes the resource release, it returns a response to the DBSC.

Fig. 10 is a diagram showing the network architecture of the above-mentioned switching from the 3G network to the 2G network and continuing to switch to another BSC. The direction of the arrow is the flow direction of the message during the preparation process of the handover, and the entities connected by the dotted line represent the network entity used for the data transmission after the handover.

2, referring to FIG. 11, in this example, a terminal needs to be switched from a 2G GSM network to a 3G TD-SCDMA network, the source controller is a BSC, and the target controller For the RNC, the method includes the following steps: S1101: When the BSC decides that the call of a terminal needs to be switched from GSM to TD-SCDMA, the enhanced handover request message ENHANCED RELOCAT I ON REQUEST is sent to the RNC through the inter-controller interface, and waits for the response of the RNC;

The enhanced handover request message may include a source cell identifier (such as CGI, RNC-ID, and Cel ID, etc.), a target cell identifier (such as CGI, RNC-ID, and Cel ID, etc.), and a source controller identifier (such as BSC-ID, CIC, etc.), target controller identity (eg RNC-ID, etc.), current call identity, current terminal identity (eg IMSI, TMSI, etc.), channel type, voice codec (eg AMR 12. 2, HR , FR, etc., terminal support capabilities (such as Clas smark 1, Clas smark 2, Clas smark 3, etc.), user plane information, transport layer information (including transport layer address and binding Id), voice version information, etc. Part or all of it.

At this time, the user plane data and/or control plane signaling of the terminal and the 2G MSC are transmitted through the Um port and the A port.

S1102: After receiving the enhanced handover request message ENHANCED RELOCATION REQUEST, the RNC reserves resources for the call, and then returns an enhanced switching response message ENHANCED RELOCATION RESPONSE to the BSC through the inter-controller interconnection interface;

The enhanced handover response message may include a cell description (such as Cel Descr ipt ion, etc.), a radio channel description, a handover reference (such as a Handover Reference, etc.), a codec (such as AMR 12. 2, etc.), frequency hopping information, and encryption information. Part or all of the information such as transport layer information (including transport layer address and binding Id).

Before transmitting the enhanced handover response message, the Iub interface transmission of the base station where the RNC and the target TD-SCDMA cell are located, and the inter-controller interface transmission between the RNC and the BSC need to be established, and the user plane data and/or control is performed after the handover. The transmission of surface signaling.

S1103: BSC ^ enhanced switching response message ENHANCED RELOCATION RESPONSE content, constructing a handover command HNADOVER COMMAND message, sent to the terminal; and BSC is responsible for establishing a connection between the A interface transmission of the call and the inter-controller interface transmission;

The A interface transmission of the call is a transmission between the BSC and the 2G MSC. In the above process, the A interface user plane link and/or the control plane link corresponding to the call may remain unchanged.

S1104: The terminal accesses the cell in the TD-SCDMA, and sends a handover complete message HANDOVER TO UTRAN COMPLETE, notifying the RNC that the handover is completed;

S1105: The RNC forwards the handover completed message to the BSC through the inter-controller interconnection interface, and notifies the BSC to tear down the resources of the call, such as releasing the ground transmission and the air interface resource. At this point, the terminal switches to 3G;

S1106: After the handover is completed, user plane data and/or control plane signaling between the terminal and the 2G MSC are transmitted through the inter-controller interface and the A interface. Since the terminal is in the TD-SCDMA network at this time, the signaling of transmission and reception needs to be in the format of the TD-SCDMA system, so the BSC or RNC may need to perform the conversion of the GSM and TD-SCDMA signaling formats.

In addition, the RNC or BSC may need to add a Transcoder and Rate Adapter Uni t (TRAU) to complete the voice codec type in the 3G network (such as TD-SCDMA) to the 2G network (such as GSM). ) Adaptation and conversion of speech codec types. For example: GSM, FR, EFR or HR codec is used in GSM. After switching, AMR and other codecs are used in TD-SCDMA. The TRAU needs to complete the corresponding codec conversion. When the inter-controller interface is IP-based For the transmission of user plane data, RTP can be used for voice data transmission. The TRAU also needs to perform grouping and unpacking processing of RTP data packets. Corresponding to the method for implementing the CS handover provided by the embodiment of the present invention, the embodiment of the present invention further provides a device for implementing CS handover, where the device is located at the source controller end. Referring to FIG. 12, the device includes: The unit U1201 is configured to initiate a handover preparation process to the target controller by using an inter-controller interconnection interface.

The response message receiving unit U602 is configured to receive an answer message after the target controller completes the reserved resource;

The handover command sending unit U603 is configured to send a handover command to the terminal according to the received response message after the target controller completes the reserved resource.

Since the types of voice codecs before and after switching may be different, the device further includes:

The codec conversion and rate adaptation unit is configured to perform coding and decoding conversion and adaptation and conversion of the speech coding and decoding type in the target network to the speech codec type in the source network. In addition, the device further includes:

a transmission unit, configured to use between the terminal and the MSC where the source controller is located after the handover is completed The head office data and/or control plane signaling is transmitted through the inter-controller interconnect interface.

Corresponding to the method for implementing the CS handover provided by the embodiment of the present invention, the embodiment of the present invention further provides another apparatus for implementing CS handover, where the apparatus is located at the target controller end. Referring to FIG. 13, the apparatus includes:

a message sending unit, configured to return a response message to the source controller after completing the resource reservation. After the handover is completed, the user plane data and/or the control plane signaling between the terminal and the MSC where the source controller is located are transmitted through the inter-controller interface. Therefore, the device further includes: a transmission unit, For user plane data and/or control plane signaling transmission through the inter-controller interface.

If the handover needs to be continued after the handover, the apparatus further includes: a handover initiation unit, configured to initiate a handover to the new target controller if the terminal needs to continue the handover after the handover is completed. The switching initiation unit includes:

a first switching initiation sub-unit, configured to perform a handover preparation process by using an inter-controller interconnection interface, where the inter-controller interconnection interface includes an inter-controller interconnection interface between the source controller and the target controller, where the target An inter-controller interface between the controller and the new target controller; or

The second handover initiation subunit is configured to initiate a handover preparation process by using an access network-core network interface. Embodiments of the present invention also provide a communication system including a first device that implements circuit switched CS switching at a source controller and a second implemented circuit switched CS switch at a target controller. The device for the first implementation of the circuit-switched CS switching of the source controller and the second device for the circuit-switched CS switching of the target controller are similar to the foregoing device embodiments of the present invention, and are not described herein again. The embodiments of the present invention can be applied to handover within the same standard network (for example, switching in 2G GSM or 3G TD-SCDMA, WCDMA network), and can also be applied to switching between different standard networks (for example, from 3G) TD-SCDMA, WCDMA switch to 2G GSM, or GSM from 2G Switch to 3G TD-SCDMA, WCDMA). Therefore, in the embodiment of the present invention, the source controller is a radio network controller RNC or a base station controller BSC, and the target controller is an RNC or a BSC. A person skilled in the art can understand that all or part of the steps of implementing the above embodiments can be completed by a program to instruct related hardware, and the program can be stored in a computer readable storage medium, and the program is executed. The method includes the following steps: the source controller initiates a handover preparation process to the target controller by using an inter-controller interconnection interface; receiving a response message after the target controller completes the reserved resource; the source controller according to the received The response message of the target controller sends a handover command to the terminal. The storage medium is, for example, R0M/RAM, a magnetic disk, an optical disk, or the like.

The foregoing detailed description of the method and system for implementing circuit switched CS switching provided by the present invention is only for helping to understand the method of the present invention and its core idea; and, for a person skilled in the art, according to the present invention The ideas will change in the specific implementation and application scope. In summary, the content of the specification should not be construed as limiting the invention.

Claims

Rights request

A method for implementing circuit-switched CS switching, comprising:

The source controller sends a handover command to the terminal according to the received response message of the target controller.

2. The method according to claim 1, wherein the method further comprises: establishing a connection between the transmission of the source controller to the source core network and the transmission of the inter-controller interface, User plane data and/or control plane signaling after handover.

3. The method according to claim 1, further comprising:

And adapting and converting the voice codec type of the network where the target controller is located and the voice codec type of the network where the source controller is located.

4. The method according to claim 1, further comprising:

The signaling format conversion of the network where the source controller is located and the network where the target controller is located.

5. A method for implementing circuit switched CS switching, characterized in that:

The target controller responds to the switch preparation process initiated by the source controller through the inter-controller interface, and reserves resources for the handover;

6. The method according to claim 5, further comprising:

Establishing a connection relationship between the interface transmission between the target controller and the target base station and the inter-controller interface transmission for the switched user plane data and/or control plane signaling transmission.

7. The method according to claim 5, further comprising:

8. The method according to claim 5, further comprising:

A device for implementing circuit-switched CS switching, located in a source controller, comprising: a handover preparation process initiation unit, configured to initiate a switch to a target controller through an inter-controller interconnection interface Change preparation process;

The response message receiving unit is configured to receive a response cancellation command sending unit, after the target controller completes the reserved resource, to send a handover command to the terminal according to the received response message of the target controller.

10. The device according to claim 9, further comprising:

And a codec conversion and rate adaptation unit, configured to perform adaptation and conversion of a voice codec type of a network where the target controller is located and a voice codec type of a network where the source controller is located.

The device according to claim 9, further comprising:

And a transmission unit, configured to transmit user plane data and/or control plane signaling between the terminal and the core network where the source controller is located, by using the inter-controller interconnection interface.

12. A device for implementing circuit-switched CS switching, located at a target controller end, and comprising:

And a message sending unit, configured to return a response message to the source controller after the resource is reserved for the handover.

13. The device according to claim 12, further comprising:

And a transmission unit, configured to perform user plane data and/or control plane signaling transmission by using the inter-controller interconnection interface.

14. The device according to claim 12, further comprising:

The switching initiation unit is configured to initiate a handover to the new target controller if the terminal needs to continue the handover after the handover is completed.

The apparatus according to claim 14, wherein the handover initiation unit comprises: a first handover initiation sub-unit, configured to perform a handover preparation process by using an inter-controller interconnection interface, where the inter-controller interconnection interface includes An inter-controller interface between the source controller and the target controller, and an inter-controller interface between the target controller and the new target controller;

Or,

The second handover initiation subunit is configured to initiate a handover preparation process by using an access network-core network interface. Communication system characterized by comprising the method of any one of claims 9 to The first implemented circuit switched CS switching device at the source controller and the second implemented circuit switched CS switching device at the target controller as claimed in any one of claims 12 to 15.