WO2010091612A1

WO2010091612A1 - Method, core network device and base station subsystem for establishing local exchange

Info

Publication number: WO2010091612A1
Application number: PCT/CN2010/070430
Authority: WO
Inventors: 朱星; 秦钧; 王之曦; 王超
Original assignee: 华为技术有限公司
Priority date: 2009-02-10
Filing date: 2010-01-30
Publication date: 2010-08-19
Also published as: CN101801046A; CN101801046B

Abstract

A method, core network device and base station subsystem for establishing a local exchange are provided, wherein a method for establishing a local exchange includes: receiving a first message requesting for handover from the first base station subsystem; based on the said first message requesting for handover, when it is determined that the two calls composing the session locate in the second base station subsystem after the handover is completed, and satisfy the local exchange condition, transmitting a second message requesting for handover to the said second base station subsystem, instructing the said second base station subsystem to establish a local exchange for said two calls after the said handover is succeeded. The technical solutions of the present invention do not need to add an extra process for establishing the local exchange, and the local exchange is realized during the handover, so the time to perform the process is saved, and the number of the message from the A interface is reduced. Because a separate process is not needed to establish a local exchange, the adverse influence to the call quality caused by establishing the local exchange is avoided, thus the user experience is improved.

Description

Method for establishing local exchange, core network device 1⁄2 station subsystem This application claims to be submitted to the Chinese Patent Office on February 10, 2009, application number 200910005199. 6 , the invention name is "establish local exchange method, core network equipment and base station The priority of the Chinese Patent Application, the entire disclosure of which is incorporated herein by reference.

Technical field

The present invention relates to the field of wireless communication technologies, and in particular, to a method for establishing a local exchange, a core network device, and a base station subsystem.

Background technique

The transmission network is an important part of the wireless communication network. Currently, operators in many countries and regions have affected the deployment, operation and service development of the wireless network because of the bottleneck of the transmission resources connecting the wireless access network and the core network. In regions such as Africa, wireless networks are growing much faster than wired networks. In areas represented by Europe, due to local laws and regulations, the construction of terrestrial cable transmission networks cannot be constructed in accordance with the needs of operators. Even countries with abundant terrestrial transmission resources, such as China, face the problem of high cost and low return on investment in the construction of transmission networks in remote areas and islands. In the above scenario, operators typically use microwave, satellite or leased terrestrial transmission lines. Therefore, P is less likely to occupy the bandwidth of the transmission network, which can effectively reduce the network construction and operation costs, and local exchange is a method for effectively reducing the bandwidth of the transmission resources.

The mobile communication system is mainly composed of a mobile station (MS, Mobile Station), a base station subsystem (BSS, Base Station Subsystem), and a network subsystem (NSS, Network Station Subsystem). Base Transceiver Station (BTS, Base Transceiver Station) and base The station controller (BSC, Base Station Controller) constitutes the BSS. The Mobile Switching Center (MSC) is located at the NSS. It controls the services of all BSCs and provides switching functions and connections to other functions in the system. 1 is a schematic diagram of a prior art global mobile communication system. The MSC 101 communicates with the BSC 102 via an A interface, the BSC 102 communicates with the BTS 103 via an Abis interface, and the BTS 103 communicates with the MS 104 via an Um interface.

Referring to FIG. 1, for a session in which the calling party and the called party are located in the same BSS, the local switching can complete the loopback of the call link in the BSS, that is, the voice data of the user plane does not flow out of the BSS, thereby implementing the specific interface transmission resource. Savings. Local exchanges include local exchanges within the BSC and local exchanges within the BTS. The local exchange in the BTS means that two calls are in the same BTS or in the same BTS cluster (in the case of BTS cascading), and the loopback of the voice link occurs in the corresponding BTS, as shown in Figure 1. The voice link loopback of MS 104-2 of MS 104-1 occurs in BTS 103-1, and the voice link loopback of MS 104-3 and MS-104-4 occurs within the BTS 103-2 cluster. By establishing a local exchange within the BTS, savings in the transmission resources of the Abis interface and the A interface can be achieved. For local switching within the BSC, both parties are located in the same BSC, but in different BTSs (BTS clusters), the voice link loopback occurs in the corresponding BSC, as shown in Figure 1, MS104-5 and MS 104. A -6 voice link loopback occurs in the BSC 102-1. By establishing a local exchange within the BSC, savings in the transmission resources of the A interface can be achieved.

The method for establishing a local exchange proposed in the prior art is as follows: After the MSC determines that two calls are to be located in the same BSS after the handover, and the local exchange condition is met, after the MSC to be switched, the BSS pair is indicated. Two calls establish a local exchange.

In the research and practice of the prior art, the inventor of the present invention finds that: after the handover process ends, the MSC indicates that the process of establishing the local exchange increases the execution time of the entire process and the number of messages of the A interface; The quality of the call has a certain impact. The local exchange also has a certain impact on the quality of the call. The two adverse effects are superimposed, which may seriously affect the user experience. SUMMARY OF THE INVENTION Embodiments of the present invention provide a method for establishing a local exchange, a core network device, and a base station subsystem, which can establish a local exchange while switching.

An aspect of the present invention provides the following method of establishing a local exchange.

Method 1 of establishing a local exchange, including:

Receiving a first message requesting handover from the first base station subsystem;

Determining, according to the requesting, the first message, that the two calls constituting the session after the handover is completed are located in the second base station subsystem and satisfying the condition of the local exchange, sending a second message requesting the handover to the second base station subsystem. And indicating that the second base station subsystem establishes a local exchange for the two calls after the handover is successful.

Method 2 of establishing a local exchange, including:

Receiving a fifth message requesting handover from the base station subsystem, the fifth message including information for establishing local exchange for two call requests constituting the session in the base station subsystem;

And determining, according to the fifth message, that a condition for establishing a local exchange for the two calls is met, sending, to the base station subsystem, a sixth message indicating that a handover operation is performed, instructing the base station subsystem to establish the two calls Local exchange.

The third method of establishing local exchange includes:

Determining, when the two calls constituting the session are located in the same base station subsystem and satisfying the condition for establishing a local exchange, transmitting, to the base station subsystem, a tenth message asking whether to switch, the tenth message including indicating that the base station subsystem is Describe two calls to establish local exchange information;

Receiving an eleventh message requesting handover from the base station subsystem, where the eleventh message includes information for establishing local exchange for the two call requests;

And transmitting, according to the eleventh message, a twelfth message indicating that the handover operation is performed to the base station subsystem, the twelfth message including information indicating that the base station subsystem establishes local exchange for the two calls. Another aspect of the present invention also provides the following core network device.

Among them, the core network device one includes:

a first receiving unit, configured to receive a message from the first base station subsystem, where the message includes a first message requesting handover;

a first determining unit, configured to determine, according to the first message that is requested to be switched received by the first receiving unit, whether two calls constituting the session are located in the second base station subsystem and satisfy a condition of local exchange; with

a first sending unit, configured to send a second message requesting handover to the second base station subsystem if the two calls are located in the second base station subsystem after the handover is completed and meet the condition of local exchange The second message includes information indicating that the second base station subsystem establishes a local exchange for the two calls after the handover is successful.

Core network equipment 2, including:

a third receiving unit, configured to receive a fifth message requesting handover from the base station subsystem, where the fifth message includes information for establishing local exchange for two call requests constituting the session in the base station subsystem;

a second determining unit, configured to determine, according to the fifth message, whether a condition for establishing local exchange between the two calls is satisfied; and

a second sending unit, configured to send, to the base station subsystem, a sixth message indicating that the switching operation is performed, when the second determining unit determines that the condition for establishing the local exchange of the two calls is satisfied, the sixth message Contains information indicating that the base station subsystem establishes a local exchange for the two calls.

The core network device 3 includes: a fourth determining unit, a third sending unit, and a fourth receiving unit, where:

a fourth determining unit, configured to determine whether two calls constituting the session are located in the same base station subsystem, and satisfy a condition of local exchange establishment;

a third sending unit, configured to: when the fourth determining unit determines that the two calls constituting the session are all located in the base station subsystem, and satisfy a condition of local exchange establishment, send a query to the base station subsystem whether to switch Tenth message, the tenth message includes information indicating that the base station subsystem establishes local exchange for the two calls; according to the fourth receiving And an eleventh message received by the unit, sending a twelfth message indicating that the handover operation is performed, where the twelfth message includes information indicating that the base station subsystem establishes local exchange for the two calls;

The fourth receiving unit is configured to receive a message from the base station subsystem, where the message includes an eleventh message requesting handover, and the eleventh message includes establishing local exchange information for the two call requests. .

Yet another aspect of the present invention also provides a base station subsystem as follows.

The base station subsystem one includes:

a first receiving unit, configured to receive a first message requesting handover from a core network side, where the first message includes information indicating that a local exchange is established for two calls constituting a session after the handover succeeds; and

And a first local exchange establishing unit, configured to establish a local exchange for the two calls according to the first message received by the first receiving unit.

Base station subsystem 2, including:

a second sending unit, configured to send a fifth message requesting handover to the core network side, where the fifth message includes information for establishing local exchange for two call requests forming a session in the base station subsystem;

a second receiving unit, configured to receive a sixth message from the core network side indicating that a handover operation is performed, where the sixth message includes indication information for establishing local exchange for the two calls; and

And a second local exchange establishing unit, configured to establish local exchange for the two calls according to the indication information that is included in the sixth message received by the second receiving unit to establish local exchange for the two calls.

An aspect of the present invention is to receive a first message requesting handover from a first base station subsystem, and according to the first message required to be switched, to determine that two calls constituting a session after the handover is completed will be located in the second base station subsystem. And when the condition of the local exchange is met, sending a second message requesting the handover to the second base station subsystem, indicating that the second base station subsystem establishes a local exchange for the two calls after the handover is successful, because no additional The process of establishing a local exchange, realizing local exchange while switching, can save the process Execution time, and save the number of messages on the A interface. Moreover, since a separate process is not required to establish a local exchange, the quality of the call is not adversely affected by establishing a local exchange, thereby improving the user experience.

According to another aspect of the present invention, by receiving a fifth message requesting handover from the base station subsystem, establishing local exchange information for the two call requests constituting the session carried in the fifth message that is required to be switched, and determining that the message is Whether the conditions for the two calls to establish a local exchange are met, and when satisfied, a sixth message indicating that the handover operation is performed instructs the base station subsystem to establish a local exchange for the two calls. It can also be seen that the method for establishing a local exchange does not need to add an additional process of establishing a local exchange, and implements local exchange at the same time of the handover, thereby saving the execution time of the process and saving the number of messages of the A interface. Moreover, since a separate process is not required to establish a local exchange, the quality of the call is not adversely affected by establishing a local exchange, thereby improving the user experience.

A further aspect of the present invention, when determining that two calls constituting a session are located in a base station subsystem and satisfying a condition for establishing a local exchange, transmitting a tenth message asking whether to switch to the base station subsystem, indicating that the base station subsystem is The two calls establish a local exchange, and when receiving the eleventh message requesting handover from the base station subsystem, establish local exchange information for the two call requests carried in the eleventh message, and send A twelfth message indicating that the handover operation is performed instructs the third base station subsystem to establish a local exchange for the two calls. It can be seen that the method for establishing a local exchange does not need to add an additional procedure for establishing a local exchange, and implements local exchange at the same time of the handover, thereby saving the execution time of the process and saving the number of messages of the A interface. Moreover, since a separate process is not required to establish a local exchange, the quality of the call is not adversely affected by establishing a local exchange, thereby improving the user experience.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a global mobile communication system in the prior art;

2 is a signaling flow of Embodiment 1 of a method for establishing local switching in an embodiment of the present invention. Schematic diagram

3 is a schematic diagram of a signaling flow of Embodiment 2 of a method 1 for establishing a local exchange according to an embodiment of the present invention;

4 is a schematic diagram of a signaling flow of Embodiment 1 of a method 2 for establishing a local exchange in an embodiment of the present invention;

FIG. 5 is a schematic diagram of a signaling flow of Embodiment 2 of a method 2 for establishing a local exchange according to an embodiment of the present invention;

6 is a schematic structural diagram of Embodiment 1 of an MSC according to an embodiment of the present invention;

7 is a schematic structural diagram of Embodiment 2 of an MSC according to an embodiment of the present invention;

8 is a schematic structural diagram of Embodiment 3 of an MSC according to an embodiment of the present invention;

9 is a schematic structural diagram of Embodiment 4 of an MSC according to an embodiment of the present invention;

10 is a schematic structural diagram of Embodiment 5 of an MSC according to an embodiment of the present invention;

11 is a schematic structural diagram of Embodiment 6 of an MSC according to an embodiment of the present invention;

FIG. 12 is a schematic structural diagram of Embodiment 1 of a BSS according to an embodiment of the present invention; FIG.

13 is a schematic structural diagram of a second embodiment of a BSS according to an embodiment of the present invention;

FIG. 14 is a schematic structural diagram of a third embodiment of a BSS according to an embodiment of the present invention.

The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. example. All other embodiments obtained by a person skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

Switching means that when a mobile station in a call enters another cell from one cell, the network can switch the mobile station from the channel used by the original cell to a certain channel of the new cell, and ensure that the user's call is not interrupted. The handover includes cells in different BSS control areas (Inter-BSS) The inter-switching and the switching between different cells in the same BSS control area (Intra-BSS) can respectively implement local switching in the above two handover procedures. The corresponding inter-BSS handover establishes local exchange and intra-BSS handover to establish local exchange, which will be described in detail below.

Method 1: Inter-BSS handover establishes local exchange: When receiving the first message requesting handover from the first BSS, it is determined that two calls constituting the session after the handover is completed will be located in the second BSS and satisfy the condition of local exchange. And sending a second message requesting handover to the second BSS, indicating that the local exchange is established for the two calls after the second BSS is successfully switched. For the convenience of description, the first message, the second message, and the like are used in the description of the present application. It can be understood that the first message and the second message are only used to distinguish different messages, and are not used to indicate the function of the message or order.

In order to enable those skilled in the art to better understand and implement the present invention, the following detailed description

Embodiment 1 In the handover process, the mobile stations MS1 and MS2 are involved. Before the handover, MS1 is located in BSS1, and MS2 is located in BSS2; after handover, both MS1 and MS2 are located in BSS2. Referring to FIG. 2, it is a signaling flow diagram of Embodiment 1 of a method for establishing a local exchange according to an embodiment of the present invention, which specifically includes the following content.

201. The BSS1 sends a Handover Required message to the MSC.

202. After the MSC determines that the two handovers corresponding to the MS1 and the MS2 are located in the BSS2 and the two calls meet the conditions of the local exchange, the MSC sends a Handover Request message to the BSS2, in the Handover Request message. The containing cell is used to indicate that the local exchange is established after the BSS2 handover succeeds.

The MSC can determine which calls can establish a local exchange. For example, the MSC can determine whether to allow two call setups of the session by recording the cell identity (Cell-ID) of the cell in which the two calls are formed, combining the codec used by the two calls and the current supplementary service requirements. Local exchange. For example, the MSC can determine whether a two-call can establish a local exchange according to the following aspects.

1) Two calls to establish a local exchange need to be in the same BSS.

2) The codec for establishing two calls for local exchange needs to be the same or compatible, or two The code converter (TC) resources of the calls are located on the BSC.

3) For supplementary services, the attributes of the service cannot conflict with the local exchange. For example, the attributes of supplementary services such as call waiting, call hold, and multi-party call conflict with the local exchange, and local exchange cannot be performed.

For each call under the same MSC, it can be uniquely identified by some means of identification. For example, the cell of the call identifier (Call-ID) can be used for identification. In addition to the Call-ID, other methods may be used, and the manner in which this document is filed does not limit it.

After the MSC determines that the two calls that constitute the session are located in the BSS2, the MSC can establish a local exchange after the BSS2 handover is completed by the cell. The cell may be: a Local Switching Indicator. . Column: The Local Switching Indicator is set to 1, indicating that BSS2 can establish local switching; the Local Switching Indicator is set to 0, indicating that BSS2 cannot establish local switching. BSS2 can establish a local exchange based on the indication of the MSC.

It can be seen that, in this embodiment, after receiving the handover request of the BSS1, the MSC determines that two calls constituting the session after the handover will be located in the BSS2, and instructs the BSS2 to establish a local exchange after the handover is completed, and the process of establishing the local exchange is performed. The switching process is performed at the same time, so that the execution time of the entire process can be saved. At the same time, the message in the switching process is used because the indication of establishing the exchange is used, so that the number of messages of the A interface can be saved. By eliminating the need to establish a separate local exchange process, the impact on call quality can be reduced and the user experience can be improved.

In the implementation process, the above method of establishing a local exchange may also be optimized, and the following is explained by another specific embodiment.

Embodiment 2 In the process of inter-BSS handover, referring to FIG. 3, it is a schematic diagram of a signaling flow of Embodiment 2 of the method 1 for establishing local exchange in the embodiment of the present invention. Before the handover, MS1 is located in BSS1, MS2 is located in BSS2; after handover, both MS1 and MS2 are located in BSS2. The difference from the first embodiment is that when the local exchange can be established, the BSS2 performs the local exchange operation after the two calls constituting the session are successfully switched, and can utilize a cell in the handover completion message. Notifying the MSC of the local exchange execution result, and the MSC clears the two calls when the local exchange establishment of the two calls is successful. The core network user plane resources are provided. The following detailed process is described in detail.

301. The BSS1 sends a handover request (Handover Required) message to the MSC.

The Handover Required message contains a list of cells to be switched by the MS, including the cell of BSS2.

302. After the MSC determines that the two calls corresponding to the MS1 and the MS2 are located in the BSS2 and the two calls satisfy the condition of the local exchange, the MSC sends a Handover Request message requesting handover to the BSS2, Handover The request message contains a cell for indicating that the local exchange can be established after the BSS2 handover succeeds.

After receiving the Handover Required message, the MSC starts to send a Handover Request message to BSS2, requesting BSS2 to allocate radio resources.

303. The BSS2 returns a Handover Request Ack message indicating a handover request response to the MSC, and uses a cell in the message (for example, Local Switch Feasibility) to notify the BSS whether the local support is currently supported. Exchange, or whether local exchange can be established.

After the BSS2 allocates radio resources to the two calls, it returns a Handover Request Ack message to the MSC to indicate whether local exchange or local exchange can be established. For example, setting the Local Switch Feasibility cell to 1 indicates that local switching is supported, or local switching can be established; setting the Local Switch Feasibility cell to 0 means that BSS2 does not support local switching, or local switching cannot be established.

304. When the MSC confirms that the BSS2 can establish a local exchange, the MSC sends a Handover Command message indicating that the handover operation is performed to the BSS1, instructing the BSS 1 to switch.

After receiving the MSC, the MSC sends a Handover Command message to the BSS1, specifically: sending a Handover Command message to the MS1 through a BTS in the BSS1, where the command includes a handover reference value allocated by the BSS2, including the frequency of the allocated channel, and the like. information. MS1 switches its frequency to a new frequency point and sends a Handover Access message to BSS2.

305. The BSS2 sends a Handover Detect message to the MSC. BSS2 detects the validity of the MSI. If it is legal, BSS2 sends a Handover Detect message to the MSC.

306. The BBS2 sends a Handover Complete message indicating that the handover is completed to the MSC, and the MSI and the BSS2 communicate normally.

BSS2 can indicate whether the local exchange is successfully established by using a cell in the Handover Complete message, such as a Local Switch Result cell.

According to the Handover Complete message, the MSC learns whether the local exchange is successfully established. If the MSC learns that the local exchange establishment is successful, the MSC can allocate the core network user plane resources allocated for the two calls; if the MSC learns that the local exchange establishment fails, the MSC reserves the The core network user plane resources allocated by the two calls continue to execute the existing call flow.

The core network user plane resources allocated by the MSC for the two calls are different according to the type of the A interface. When the bearer type of the A interface is Time Division Multiplex (TDM), the core network user plane resources allocated by the MSC for the two calls include the circuit identification code (CIC) of the two calls. When the bearer type of the A interface is the Internet Protocol (IP), the core network user plane resources allocated by the MSC for the two calls include the IP connection endpoint (IP) located on the Media Gateway (MGW, Media Gateway). Address + port number) and so on.

After the local exchange is successfully established, the MSC releases the core network user plane resources allocated for the two calls, and the resources are resources related to the A interface, thereby saving the transmission resources of the A interface.

307. After receiving the Handover Complete message, the MSC releases the resources related to the MSI in the BSS1 by using a Clear Command message indicating the clearing of the resource.

The resources related to MS1 in BSS1 include related radio resources.

308. After the resource release related to the MS1 in the BSS1 is completed, the BSS1 sends a Clear Complete message indicating that the resource clearing is completed to the MSC.

At this point, one switching process is completed.

It can be seen that, in this embodiment, the local exchange can be established at the same time of the handover, so that the number of messages of the A interface and the execution time of the processing flow can be saved, and the impact on the call quality can be reduced. Further, the embodiment can also be locally switched. After the establishment is successful, The MSC releases the core network user plane resources allocated for the two calls, thereby saving transmission resources.

In implementation, in step 303, if the Handover Request Ack message sent by the BSS2 indicates that the local exchange cannot be established for the two calls, the existing handover procedure may be continued, and the two calls may be instructed to be released by the BSS1 and the BSS2. . Or after the handover procedure ends (i.e., after step 308 is performed), the MSC instructs BSS2 to establish a local exchange for the two calls. Therefore, the local exchange can be established for the two calls, and after the local exchange is established, the core network user plane resources allocated for the two calls are released, so as to save the A interface resources as much as possible.

Method 2: Intra-BSS handover establishes local exchange: The MSC receives a fifth message requesting handover from the third BSS, where the fifth message includes information for establishing local exchange for two call requests constituting the session; And a fifth message from the third BSS, when it is determined that the condition for the two calls to establish the local exchange is satisfied, sending a sixth message indicating that the handover operation is performed, instructing the third BSS to establish a local exchange for the two calls. The invention will be described in detail below with reference to the accompanying drawings, in which FIG.

In the first embodiment, both MS1 and MS2 are located in a certain BSS (set to BSS3), but no local exchange is established. Referring to FIG. 4, it is a schematic diagram of a signaling flow of Embodiment 1 of a method for establishing a local exchange according to an embodiment of the present invention, which is described in detail below through specific steps.

401. The BSS3 sends, to the MSC, an Internal Handover Required message indicating that the handover is requested, where the message carries information for establishing a local exchange.

The message may carry the call identifiers of the calls corresponding to the MS1 and the MS2, and are respectively set to Call-ID1 and Call-ID2, and apply for establishing local exchange information for the two calls.

For example, a Local Switch Indicator cell can be set in the message. When the Local Switch Indicator cell is set to 1, it indicates that the call Call-ID1 and the Call-ID2 application establish a local exchange.

For each call under the same MSC, it can be uniquely identified by some means of identification. For example, the cell of the call identifier (Call-ID) can be used for identification. In addition to the Call-ID, other methods can be used, and the method described in this application does not constitute Become a limit.

402. When the MSC determines that the condition for establishing the local exchange of the two calls is satisfied, the MSC sends an Internal Handover Command message indicating that the handover operation is performed to the BSS3, indicating that the BSS3 is the two calls (Call-ID 1 and Call-ID2) Establish a local exchange.

The MSC determines whether the two calls (Call-ID 1 and Call-ID2) satisfy the condition for establishing a local exchange, and may adopt the same technical means as in the technical solution described in the first method.

For example, a Local Switch Indicator cell can be set in the Internal Handover Command message. When the Local Switch Indicator cell is set to 1, it indicates that the call Call ID 1 establishes a local exchange with Call-ID2.

403. The BSS3 returns a handover complete (Handover Complete) message indicating that the handover is completed to the MSC.

It can be seen that, in this embodiment, when the handover request message received by the MSC includes information for establishing local exchange for two call requests constituting the session, and the conditions for the two calls to establish local exchange are satisfied, the message is sent. Instructing the BSS to establish a local exchange, so that the local exchange can be established at the same time of the handover, which saves the process execution time. At the same time, since the handover message indicates whether the local exchange is established, no additional local exchange message is needed, so the interface A can be saved. The number of messages; and the local exchange and the handover process are the same process, so that the impact of the separate local exchange processing process on the call quality can be avoided, and the user experience is improved.

In a specific embodiment, the Handover Complete message in step 403 may carry a cell (for example, a Local Switch Result cell) to indicate the execution result of the local exchange. If the local exchange is successfully established, the MSC can clear the core network user plane resources allocated for the two calls, so that the transmission resources of the A interface can be saved; and the local exchange in the BTS can also save related information. The Abis interface transmits resources. If the local exchange establishment fails, the core network user plane resources allocated for the two calls are reserved, and the subsequent call flow is continued. When the MSC learns that the local exchange establishment fails, it can also actively instruct the BSS to establish a local exchange after the handover is completed.

In the first embodiment of the method 2, if the condition for establishing the local exchange is not satisfied, Then, after performing step 401, the handover procedure initiated by the BSS3 may be rejected by using an Internal Handover Required Reject message indicating that the internal handover request is rejected. The reason value may be set as: Not allowed to establish a local exchange (Not allowed to establish Local Switch ).

If the MSC finds that the two calls are located in the same BSS and the conditions for establishing the local exchange are met, but the local exchange has not been established, the MSC may also initiate a handover procedure, which is described below by way of a specific embodiment.

FIG. 5 is a schematic diagram of a signaling flow of Embodiment 2 of a method 2 for establishing a local exchange according to an embodiment of the present invention.

501. The MSC sends an internal handover request (Internal Handover Enquiry) message to the BSS3, asking whether to switch, the message carrying the cell indicating that the BSS3 is a call corresponding to the MS1 and the MS2 (set to Call-ID1, Call-ID2) to establish a local exchange.

The MSC pre-determines whether the call of Call-ID1 and Call-ID2 meets the conditions for establishing a local exchange, and may adopt the same technical means as in the technical solution described in the first method, and is not described again. And when the conditions of the local exchange are met, an Internal Handover Enquiry message is sent to the BSS3, instructing the BSS3 to establish a local exchange for the call Call-ID 1 and Call-ID2. The Internal Handover Enquiry message can trigger a subsequent handover process.

502. The BSS3 sends an Internal Handover Required message to the MSC, where the message includes information for establishing a local exchange for the two calls (Call-ID1 and Call-ID2).

503. When the MSC determines that the two calls (Call-ID1 and Call-ID2) establish a local exchange condition, the MSC sends an Internal Handover Command message to the BSS3, indicating that the BSS3 is the two calls. -IDl and Call-ID2) Establish local exchange.

504. The BSS3 returns a Handover Complete message to the MSC. In the Handover Complete message, a cell (for example, a Local Switch Result cell) may be carried to indicate the execution result of the local exchange. If the local exchange is successfully established, the MSC can clear the core network user plane resources allocated for the two calls, thereby saving the transmission resources of the A interface related thereto. If the local exchange establishment fails, the core network user plane resources allocated for the two calls are reserved, and the subsequent call flow is continued. When the MSC learns that the local exchange establishment fails, the MSC may also actively instruct the BSS to establish a local exchange.

In the first embodiment of the second method, if the condition for establishing the local exchange is not satisfied, after the step 401 is performed, the handover procedure initiated by the BSS3 may be rejected by using an Internal Handover Required Reject message. Can be set to: Not allowed to establish Local Switch.

It can be seen that, in this embodiment, the internal handover inquiry message is sent by the MSC, the handover process is triggered, and the local exchange is established in the handover process, so that the process execution time can be saved, and since the local exchange is established by the message in the handover process, Therefore, the number of messages of the A interface can be saved.

In a specific implementation, when the MSC sends an Internal Handover Enquiry message to the BSS3, if the message carries a message indicating that the BSS3 is a call corresponding to the MSI and the MS2 (set to Call-ID1, Call-ID2) to establish a local exchange, the BSS3 Sending an Internal Handover Required message to the MSC, where the message includes information for establishing local exchange for the two calls (Call-ID 1 and Call-ID2), at this time, the MSC does not need to repeatedly determine whether the two calls are In accordance with the conditions for establishing the local exchange, the internal Handover Command message is directly sent to the BSS3, and the BSS3 is instructed to establish a local exchange for the two calls (Call-ID1 and Call-ID2). The other steps are similar to the foregoing embodiment, and are not described again.

It should be understood that the embodiments of the present application are not intended to limit the present invention. For example, the message used in establishing the local exchange process does not limit the message composition, and the message composition (including the cell structure) may be implemented in the message. Flexible definition based on delivery.

The MSCs in the embodiments of the present invention are described in detail in the following description. FIG. 6 is a schematic structural diagram of Embodiment 1 of an MSC according to an embodiment of the present invention. The MSC may be used to establish a local exchange when inter-BSS handover, and specifically includes: a first receiving unit 601, a first determining unit 602, and a A transmitting unit 603.

The first receiving unit 601 receives the message from the first BSS, where the message includes the first message requesting the handover; the first determining unit determines, according to the first message received by the first receiving unit 601, that the session is completed after the handover is completed. Whether the two calls are located in the second BSS and meet the conditions of the local exchange; the first sending unit 603 sends a message to the second BSS, where the message includes: after the handover is completed, the two calls will be located in the second BSS and meet the local And the second message of the request switching of the local exchange is established for the two calls after the second BSS is successfully switched.

The MSC can determine which calls can establish a local exchange. For example, the MSC can determine whether to allow two call setups of the session by recording the cell identity (Cell-ID) of the cell in which the two calls are formed, combining the codec used by the two calls and the current supplementary service requirements. Local exchange.

It can be seen that, when receiving the request to switch the first message from the first BSS, the MSC in this embodiment determines whether the two calls constituting the session are located in the second BSS after the completion of the handover and meet the conditions of the local exchange, and complete the handover. After the two calls are both located in the second BSS and meet the conditions of the local exchange, the second message sending the request handover indicates that the second BSS is successfully switched to establish a local exchange for the two calls. It can be seen that the establishment of the local exchange is completed in the handover process, so that the execution time of the entire process can be saved. At the same time, since the indication of establishing the local exchange is implemented by switching the message in the process, the A interface can be saved. The number of messages.

FIG. 7 is a schematic structural diagram of a second embodiment of an MSC according to an embodiment of the present invention. The MSC 700 is different from the MSC embodiment. The MSC 700 further includes: a second receiving unit 701 and a first resource management. Unit 702. The second receiving unit 701 is configured to receive a message from the second BSS, where the message includes a third message indicating that the handover is complete, and the third message includes a message indicating whether the local exchange is successfully established. The first resource management unit 702, The core network user plane resource allocated for the two calls is cleared when the third message received by the second receiving unit 701 includes information indicating that the local exchange establishment is successful; and may also be received by the second receiving unit 701. When the third message contains information indicating that the local exchange establishment fails, the core network user plane resources allocated for the two calls are reserved.

The core network user plane resources allocated by the MSC for the two calls are different according to the type of the A interface. When the bearer type of the A interface is TDM, the core network user plane resources allocated by the MSC for the two calls include the CIC of the two calls, etc.; when the type of the A interface is IP, the MSC is the The core network user plane resources allocated for the two calls include the IP connection endpoint (IP address + port number) located on the MGW.

After the local exchange is established, the core network user plane resources allocated for the two calls constituting the session are cleared, which can save the transmission resources of the A interface.

In a specific implementation, the message received by the second receiving unit 701 may further include a fourth message indicating a handover request response, where the fourth message includes information indicating that the second BSS cannot establish a local exchange; corresponding, the first sending The message sent by the unit 603 may further include: when the second receiving unit 701 receives the fourth message that the second BSS cannot establish the information of the local exchange, the first BSS and the second BSS are instructed to release the message of the two calls. Or, when the fourth message received by the second receiving unit 701 includes information that the second BSS cannot establish local exchange for the two calls, after the handover is completed, the second BSS is instructed to establish a locally exchanged message. Therefore, the local exchange can be established for the two calls, and after the local exchange is established, the core network user plane resources allocated for the two calls are released, so as to save the A interface resources as much as possible.

FIG. 8 is a schematic structural diagram of Embodiment 3 of an MSC according to an embodiment of the present invention. The MSC may be used to establish a local exchange when switching between Intra-BSS, and specifically includes: a third receiving unit 801, a second determining unit 802, and a Two transmitting unit 803.

The third receiving unit 801 is configured to receive a message from the third BSS, where the message includes a fifth message requesting handover, where the fifth message includes a session formed in the third BSS The two call requests establish the locally exchanged information; the second determining unit 802 is configured to determine, according to the fifth message from the third BSS, whether the condition for establishing the local exchange of the two calls is satisfied; the second sending unit 803. The message is sent to the third BSS, where the message includes: when the second determining unit 802 determines that the condition that the two calls establish local exchange is satisfied, the sixth message indicating that the handover operation is performed, the sixth message Contains information indicating that the third BSS establishes a local exchange for the two calls.

The MSC can determine which calls can establish a local exchange. For example, the MSC can determine whether to allow two call setups of the session by recording the cell identity (Cell-ID) of the cell in which the two calls constituting the session are located, combining the codec used by the two calls and the current supplementary service requirements. Local exchange.

And the MSC can uniquely identify each call under the MSC by using some means of identification. For example, a cell with a call identifier (Call-ID) can be used for identification. In addition to the Call-ID, other methods may be used, and the manner in which this document is filed does not limit it.

It can be seen that, when receiving the fifth message requesting handover of the local exchange for the two calls constituting the session, the MSC determines whether the two calls meet the condition of the local exchange, and satisfies the local condition. When the condition of the exchange is sent, the sixth message indicating that the handover operation is performed is instructed that the third BSS establishes a local exchange for the two calls. It can be seen that the MSC can implement local exchange during the handover process, since no separate The local exchange establishment process can save the process execution time, and the number of messages of the A interface can be saved because the message in the handover process is used to indicate whether the local exchange is established. The establishment of the local exchange and handover process is performed at the same time, which also avoids the impact on the quality of the handover when the separate process of establishing the local exchange is performed separately, so that the user experience can be improved.

FIG. 9 is a schematic structural diagram of a fourth embodiment of an MSC according to an embodiment of the present invention, which is different from the third embodiment of the MSC, where the second resource management unit is further included in the fourth embodiment of the MSC.

901

The message received by the third receiving unit 801 further includes a seventh message indicating that the handover is complete, and the seventh message includes the third BSS establishing a local handover for the two calls. Corresponding to the success of the information; correspondingly, the second resource management unit 901 is configured to: when the third BSS includes the information that the third BSS establishes a local exchange success for the two calls, The core network user plane resource allocated by the two calls; and may be further configured to: when the third BSS includes the information that the local BSS fails to establish a local exchange for the two calls, The assigned core network user plane resources.

The core network user plane resources allocated by the MSC for the two calls are different according to the bearer type of the A interface. When the bearer type of the A interface is TDM, the core network user plane resources allocated by the MSC for the two calls include the CICs of the two calls, etc. When the bearer type of the A interface is IP, the MSC is the two The core network user plane resources of the call distribution include the IP connection endpoint (IP address + port number) located on the MGW.

After the local exchange is established for the two calls, the A-interface transmission resource can be saved by clearing the core network user plane resources allocated for the two calls, and the Abis interface transmission resource can be saved under the local exchange in the BTS. .

Moreover, the message sent by the second sending unit 803 may further include: when the second determining unit 802 determines that the condition that the two calls establish local exchange is not satisfied, the rejection sent to the third BSS is The indication that the two calls establish a locally switched handover request rejects the eighth message of the handover request.

10 is a schematic structural diagram of a fifth embodiment of an MSC according to an embodiment of the present invention. The MSC embodiment is extended on the basis of the fourth embodiment of the MSC embodiment, and is further illustrated in FIG. The third determining unit 1001 is configured to determine whether the two calls are located in the same base station subsystem and meet the condition for establishing a local exchange, and the local exchange is not established.

The message sent by the second sending unit 803 further includes: when the third determining unit 1001 determines that the two calls are located in the third BSS and meets the condition for establishing a local exchange, and does not establish a local exchange, sends the message to the third BSS. Querying whether the ninth message is switched, the ninth message includes a message indicating that the third BSS establishes a local exchange for the two calls. Referring to FIG. 11, FIG. 11 is a schematic structural diagram of Embodiment 5 of an MSC according to an embodiment of the present invention. The method includes: a fourth determining unit 1101, a third transmitting unit 1102, and a fourth receiving unit 1103. The fourth determining unit 1101 is configured to determine whether the two calls constituting the session are located in the third BSS, and satisfy the condition of the local exchange establishment, and the local exchange is not established; the third sending unit 1102 is configured to send the third call to the third BSS. The message includes: when the fourth determining unit 1101 determines that both calls constituting the session are located in the third BSS, and the condition of the local exchange establishment is satisfied, whether the inquiry sent to the third BSS is switched Tenth message, the tenth message includes information indicating that the third BSS establishes local exchange for the two calls; according to the eleventh message received by the fourth receiving unit 1103, the tenth indication that the switching operation is performed is sent The second message, the twelfth message includes information indicating that the third BSS establishes a local exchange for the two calls. The fourth receiving unit 1103 is configured to receive a message from the third BSS, where the message includes an eleventh message requesting handover, and the eleventh message includes information for establishing local exchange for the two call requests.

It can be seen that, when determining that two calls constituting a session are located in the third BSS and satisfying the condition for establishing a local exchange, the MSC in the embodiment sends a tenth message asking whether to switch, to the third BSS, indicating the third The BSS establishes a local exchange for the two calls, and establishes a local exchange for the two call requests carried in the eleventh message when receiving the eleventh message requesting the handover from the third BSS. Information, transmitting a twelfth message indicating that the handover operation is performed instructing the third BSS to establish a local exchange for the two calls. It can be seen that the method for establishing a local exchange does not need to add an additional process for establishing a local exchange, and implements local exchange at the same time of the handover, thereby saving the execution time of the process and saving the number of messages of the A interface. Moreover, since a separate process is not required to establish a local exchange, the quality of the call is not adversely affected by establishing a local exchange, thereby improving the user experience.

The following describes the BSS involved in establishing the local exchange process in the embodiment of the present invention with reference to the accompanying drawings:

FIG. 12 is a schematic structural diagram of Embodiment 1 of a BSS according to an embodiment of the present invention. The BSS includes: a first receiving unit 1201 and a first local exchange establishing unit 1202. The first receiving unit 1201 is configured to receive a message from a core network side, where the message includes a first message requesting a handover, where the first message includes indicating that the handover is successful, and establishing a local exchange for two calls constituting the session. Information; a first local exchange establishing unit 1202, configured to The first message received by the first receiving unit 1201 establishes a local exchange for the two calls.

It can be seen that, when receiving the first message requesting handover from the core network side, the BSS establishes local exchange indication information for the two calls constituting the session according to the handover successfully carried in the first message. The two calls establish a local exchange. Therefore, the BSS can implement switching and local switching at the same time, thereby saving process execution time. At the same time, since the message in the handover process carries information indicating whether to establish local exchange, the number of messages of the A interface can be saved. The simultaneous execution of the handover and the local exchange also avoids the impact on the quality of the call when the handover and the local exchange are performed separately, thereby improving the user experience.

The applicable scenario of the BSS is as follows: Inter-BSS handover establishes a local exchange process, for example, two calls in different BSSs before handover, and are located in the same BSS after handover, and meet the conditions of local exchange, the BSS can A local exchange is established for the two calls.

In a specific implementation, the above BSS can be further optimized and described in a specific embodiment.

FIG. 13 is a schematic structural diagram of a second embodiment of a BSS according to an embodiment of the present invention. On the basis of an embodiment of the BSS embodiment, the first sending unit 1301 is configured to send a message to the core network, including establishing in the first local exchange. After the local exchange is performed on the two calls, the unit 1202 sends a third message to the core network side indicating that the handover is complete, and the third message includes information about whether the local exchange is successful for the two calls, so that the core network The side clears the core network user plane resources allocated for the two calls when the local exchange establishment is successful, or reserves the core network user plane resources allocated for the two calls when the local exchange establishment fails.

After the local exchange is successfully established, the BSS introduced in the embodiment can send a local exchange establishment success message to the core network to instruct the core network to clear the core network user plane resources allocated for the two calls, thereby saving related A. Interface transmission resources.

14 is a schematic structural diagram of a third embodiment of a BSS according to an embodiment of the present invention. The BSS 1400 includes: a second sending unit 1401, a second receiving unit 1402, and a second local switching establishing unit 1403. The second sending unit 1401 is configured to send a message to the core network side, where The message includes a fifth message requesting to switch, the fifth message includes information for establishing a local exchange for two call requests constituting the session, and a second receiving unit 1402, configured to receive a message from the core network side. The message includes a sixth message indicating that the handover operation is performed, the sixth message includes indication information for establishing a local exchange for the two calls, and a second local exchange establishing unit 1403, configured to be used according to the second receiving unit 1403. The indication carried in the received sixth message establishes local exchange indication information for the two calls, and establishes local exchange for the two calls.

It can be seen that the BSS first sends a fifth message requesting handover to the core network side to establish a local exchange, and after receiving the sixth message from the core network side, according to the handover succeeded in the sixth message, The two calls making up the session establish indications of local exchanges, establishing a local exchange for the two calls. Therefore, the BSS can implement switching and local switching at the same time, thereby saving process execution time. At the same time, since the message in the switching process carries information indicating whether to establish local exchange, the number of messages of the A interface can be saved. The simultaneous execution of the handover and the local exchange also avoids the impact on the quality of the call when the handover and the local exchange are performed separately, thereby improving the user experience.

The applicable scenario of the BSS is as follows: Intra-BSS handover establishes a local exchange process. For example, when two calls are always located in the same BSS before and after the handover, and the conditions of the local exchange are met, the BSS may be the two The call establishes a local exchange.

In a specific implementation, the BSS may be extended. For example, the message sent by the second sending unit 1401 further includes: when the local exchange is successfully established for the two calls, the indication sent to the core network side is completed. The seventh message, the seventh message includes indication information that the local exchange is successful for the two calls, so that the core network side clears the core network user plane resources allocated for the two calls.

After the local exchange is successfully established, the BSS in the embodiment sends a message indicating that the local exchange is successfully established to the core network, and instructs the core network to clear the core network user plane resources allocated for the two calls. In the TDM mode, The related A interface transmission resources can be saved, and the local exchange in the BTS can also save the Abis interface transmission resources.

The message received by the second receiving unit 1402 may further include a ninth message from the core network side to establish whether the local exchange inquiry is to be switched, and the ninth message includes the indication The base station subsystem establishes the local exchange indication information for the two calls. Correspondingly, the second sending unit 1401 sends the request to switch when the second receiving unit 1402 receives the ninth message for establishing the local exchange. Five news.

The above is described in detail by the specific application in the Global System for Mobile Communications (GSM). It can be understood that the method for establishing local exchange introduced in the embodiment of the present invention can also be applied to the wideband code division. (WCDMA, Wideband Code Division Multiple Access), Time Division Synchronous Code Division Multiple Access (TD-SCDMA), Long Term Evolution (LTE), and other wireless communication systems. The corresponding device is the corresponding core network device (such as: MSC server) and the base station subsystem (specifically, RNC (Radio Network Controller) or base station (NodeB)) in the system. No longer - an example .

It can be understood that the first and second equivalent systems, devices or units used in the embodiments of the present invention do not indicate a certain order, but are convenient for description, and are used to distinguish different systems, devices or units. The system, device or unit can implement the functions of the embodiments of the present invention.

A person skilled in the art may understand that all or part of the various steps of the foregoing embodiments may be completed by a program instructing related hardware. The program may be stored in a computer readable storage medium, and the storage medium may include: ROM, RAM, disk or CD, etc.

The method for establishing a local exchange, the core network device, and the base station subsystem provided by the embodiments of the present invention are described in detail. The principles and implementation manners of the present invention are described in the specific examples. The description of the above embodiments is only The method for understanding the present invention and its core idea; at the same time, for those skilled in the art, according to the idea of the present invention, there will be changes in the specific embodiment and the scope of application. The description should not be construed as limiting the invention.

Claims

Claim

A method for establishing a local exchange, comprising:

Determining, according to the requesting, the first message, that the two calls constituting the session after the handover is completed are located in the second base station subsystem and satisfying the condition of the local exchange, sending a second message requesting the handover to the second base station subsystem. Instructing the second base station subsystem to establish a local exchange for the two calls.

2. The method of establishing a local exchange according to claim 1, further comprising:

Receiving a third message from the second base station subsystem indicating that the handover is completed, and when the third message includes information for establishing a local exchange success for the two calls, clearing the core allocated for the two calls Network user area resources;

Or receiving a third message from the second base station subsystem indicating that the handover is completed, and when the third message includes information that the local exchange fails to be established for the two calls, the two call assignments are reserved. The core network user plane resources, and continue to handle the call.

The method for establishing a local exchange according to claim 1 or 2, further comprising:

Receiving a fourth message from the second base station subsystem indicating a handover request response, and when the fourth message includes information that cannot be locally exchanged for the two calls, indicating the first base station subsystem and The second base station subsystem releases the two calls; or receives a fourth message from the second base station subsystem indicating a handover request response, when the fourth message includes not being able to serve the two calls When the locally exchanged information is established, the second base station subsystem is instructed to establish a local exchange for the two calls after the handover is completed.

4. A method of establishing a local exchange, the method comprising:

Receiving a fifth message from the base station subsystem requesting handover, the fifth message including establishing a local exchange for two call requests constituting the session in the base station subsystem Information

The method of establishing a local exchange according to claim 4, further comprising:

Receiving a seventh message indicating that the handover is completed by the base station subsystem, and when the seventh message includes information for establishing a local exchange success for the two calls, clearing a core network user allocated for the two calls Surface resources;

Or receiving a seventh message indicating that the handover is completed by the base station subsystem, and when the seventh message includes information that the local exchange fails to be established for the two calls, retaining the core allocated for the two calls Network user plane resources, and continue to perform call processing; or, receiving a seventh message indicating that the handover is completed by the base station subsystem, when the seventh message includes information for establishing local exchange failure for the two calls After the handover is completed, the base station subsystem is instructed to establish a local exchange for the two calls.

If the condition for establishing a local exchange for the two calls is not met, an eighth message indicating rejection of the handover request is sent to the base station subsystem, refusing to establish a local exchange for the two calls.

The method of establishing a local exchange according to any one of claims 4 to 6, characterized in that, before the receiving the fifth message requesting handover from the base station subsystem, further comprising:

Determining, when the two calls satisfy the condition for establishing a local exchange, sending a ninth message to the base station subsystem asking whether to switch, the ninth message including instructing the base station subsystem to establish a local exchange for the two calls Information.

8. A method of establishing a local exchange, the method comprising:

Determining, when the two calls constituting the session are located in the same base station subsystem and satisfying the condition for establishing a local exchange, sending a tenth message asking whether to switch to the base station subsystem, The tenth message includes information indicating that the base station subsystem establishes local exchange for the two calls;

And transmitting, according to the eleventh message, a twelfth message indicating execution of a handover operation to the base station subsystem, the twelfth message including information indicating that the base station subsystem establishes local exchange for the two calls.

9. A core network device, characterized by comprising:

a first sending unit, configured to send a second message requesting handover to the second base station subsystem if the two calls are located in the second base station subsystem after the handover is completed and meet the condition of local exchange The second message includes information indicating that the second base station subsystem establishes a local exchange for the two calls.

The core network device according to claim 9, further comprising: a second receiving unit, configured to receive a third message from the second base station subsystem indicating that the handover is completed, in the third message Contains information indicating whether the local exchange was successfully established; and

a first resource management unit, configured to: when the third message received by the second receiving unit includes information indicating that the local exchange is successfully established, clear the core network user plane resource allocated for the two calls; or When the third message received by the second receiving unit includes information indicating that the local exchange establishment fails, the core network user plane resources allocated for the two calls are reserved.

The core network device according to claim 9 or 10, wherein the second receiving unit is further configured to receive a fourth message indicating a handover request response, where the fourth message includes the second base station The system cannot establish a locally exchanged message for the two calls. The first sending unit is further configured to: when the fourth message received by the second receiving unit includes information that the second base station subsystem cannot establish local exchange for the two calls, indicating the first The base station subsystem and the second base station subsystem release the two calls; or the fourth message received at the second receiving unit includes the second base station subsystem failing to establish a local exchange for the two calls The information indicates that the second base station subsystem establishes a local exchange after the handover is completed.

12. A core network device, comprising:

The core network device according to claim 12, further comprising a second resource management unit,

The third receiving unit is further configured to receive a seventh message from the base station subsystem indicating that the handover is complete, where the seventh message includes information that the base station subsystem establishes whether the local exchange is successful for the two calls;

The second resource management unit is configured to: when the seventh message includes the information that the base station subsystem establishes a local exchange success for the two calls, clear the core network user plane allocated for the two calls And storing, in the seventh message, the information about the core network user plane allocated to the two calls when the base station subsystem establishes information that the local exchange fails for the two calls.

The core network device according to claim 12, wherein the second sending unit is further configured to determine, in the second determining unit, that the two calls are locally established. When the condition of the exchange is not satisfied, an eighth message indicating that the handover request is rejected is sent to the base station subsystem, and the local exchange is refused for the two calls.

The core network device according to any one of claims 12 to 14, further comprising: a third determining unit, configured to determine whether the two calls are located in the same base station subsystem and satisfy local exchange establishment conditions of;

The second sending unit is further configured to: when the third determining unit determines that the two calls are located in the base station subsystem and meet the condition for establishing a local exchange, send a ninth message asking whether to switch to the base station subsystem, The ninth message includes information indicating that the base station subsystem establishes a local exchange for the two calls.

A core network device, comprising: a fourth determining unit, a third sending unit, and a fourth receiving unit, wherein:

a third sending unit, configured to: when the fourth determining unit determines that the two calls constituting the session are all located in the base station subsystem, and satisfy a condition of local exchange establishment, send a query to the base station subsystem whether to switch a tenth message, the tenth message includes information indicating that the base station subsystem establishes local exchange for the two calls; and according to the eleventh message received by the fourth receiving unit, transmitting a tenth indicating that the switching operation is performed a second message, the twelfth message includes information indicating that the base station subsystem establishes local exchange for the two calls;

17. A base station subsystem, comprising:

The base station subsystem according to claim 17, further comprising: a first sending unit, configured to: after the first local exchange establishing unit establishes a local exchange for the two calls, The core network side sends a third message indicating that the handover is complete, and the third message includes information about whether the local exchange is successful for the two calls, so that the core network side clears to the two when the local exchange establishment is successful. The core network user plane resource of the call is allocated, or the core network user plane resource allocated for the two calls is reserved when the local exchange establishment fails.

19. A base station subsystem, comprising:

The base station subsystem according to claim 19, wherein the second sending unit is further configured to: when the local exchange is successfully established for the two calls, send the indication that the handover is completed to the core network side. The seventh message, the seventh message includes indication information that the local exchange is successful for the two calls.

The base station subsystem according to claim 19 or 20, wherein the second receiving unit is further configured to receive a ninth message from the core network side to query whether to switch, the ninth message includes Instructing the base station subsystem to establish local exchange indication information for the two calls;

The second sending unit sends the fifth message when the second receiving unit receives the ninth message.