WO2010102584A1

WO2010102584A1 - Calling handover method within a base station system and mobile communication system

Info

Publication number: WO2010102584A1
Application number: PCT/CN2010/071025
Authority: WO
Inventors: 李靖; 王欣晖
Original assignee: 中兴通讯股份有限公司
Priority date: 2009-03-13
Filing date: 2010-03-12
Publication date: 2010-09-16
Also published as: CN101835219A

Abstract

The present invention provides a calling handover method within a base station system (BSS), a base station controller (BSC), a BSS and a mobile communication system. Therein, the method includes the following steps: a mobile switching center (MSC) transmits an internal handover command message to the BSC after it receives an internal handover required message transmitted from the BSC; if the BSC acquires that the first calling corresponding to the internal handover command message and the second calling within the BSC constitute a local call after the handover of the first calling, it establishes an internal channel and completes the follow-up handover operations after receiving the internal handover command message, wherein the internal channel is used for transmitting the user plane speech of the first calling and of the second calling between the first calling user and the second calling user without passing through a core network. The invention enables that the user plane speech of the callings constituting the local call can be directly transmitted without passing through a media gateway (MGW) of the core network after the calling handover within the BSS is completed. The transmission resources waste of the Abis interface and of the A interface is avoided.

Description

Call switching method and mobile communication system in base station system

Technical field

The present invention relates to the field of communications, and in particular, to a call handover method and a mobile communication system in a base station system (BSS).

Background technique

In the existing Global System for Mobile Communications (GSM), the Mobile Switching Center Server (MSC Server or MSC), the Media Gateway (MGW) and the base station The controller (Base Station Controller, BSC for short) communicates with the A interface; and the mobile terminal (Mobile Station, MS for short) communicates with the base station (Base Transceiver Station, BTS for short) through the Um interface; In addition, the BTS and the BSC are connected through an Abis interface. The MSC is used to manage the management of the surface related functions, and the MGW is used for the management of the user voice.

When the call is established, the GSM system is based on the TDM (Time Division Multiplexing) bearer and the IP (Internet Protocol) bearer. In the process of assigning the A interface, it will be The call is assigned a call identity.

Figure 1 is a flow chart of call switching in a BSS (including BSC and BTS) in the existing GSM system. As shown in Figure 1, the process includes the following steps:

101: The MS sends a measurement report to the BTS1, and the BTS 1 forwards the measurement report to the BSC;

102: The BSC sends an Internal Handover Required message to the MSC.

103: The MSC sends an Internal Handover Command message to the BSC.

104: The BSC sends a Channel Activation message to the BTS2 of the target cell to activate the channel.

105: After receiving the channel activation message, the BTS2 sends a channel activation confirmation (Channel) to the BSC. Activation Acknowledge ) message;

106: After receiving the channel activation confirmation message sent by the BTS2, the BSC sends a Handover Command message to the BTS1, and the BTS1 forwards the message to the MS;

107: After receiving the handover command message, the MS attempts to access from the BTS2, and sends a Handover Access message to the BTS2;

108: After receiving the Handover Access message sent by the MS, the BTS2 sends a Handover Detect message to the BSC.

109 - 110: BTS2 sends a PHY INFO (physical information) message to the MS, which includes synchronization information such that the MS can correctly access the content;

111 : After receiving the PHY INFO, the MS sends SABM (Set Asynchronous Balanced)

Mode, set the asynchronous balance mode) frame to BTS2;

112: After receiving the SABM frame, the BTS2 sends an Establish IND message to the BSC to notify the BSC that the radio link is established.

113: At the same time that the setup establishment indication message is sent, the BTS2 responds to the MS with a UA (Unnumbered Acknowledgement) frame, and notifies the MS radio link layer to establish;

114: The MS sends a Handover Complete message to the BTS2, and the BTS2 forwards the handover complete message to the BSC, to notify the BSC that the handover is completed.

115: The BSC sends a handover complete message to the MSC.

Currently, in the GSM system, for the ongoing call, the user plane voice of the calling party is transmitted from the BSC to the MGW through the A interface, and then transmitted by the MGW to the BSC of the calling party, even if both parties are in the same BSC. However, in the actual GSM system, there are a large number of local calls. The so-called local call means that both parties of the call belong to the same BTS, or belong to different BTSs under the same BTS cluster (BTS under the same BTS cluster). All belong to one BSC), or belong to the same BSC. For these local calls, if the current call processing flow is followed: 1) For calls belonging to the same BTS, the user's voice of the calling party will pass.

The Abis port of the BTS is transmitted to the BSC, and the BSC transmits the user plane voice to the MGW. The MGW then transmits the user plane voice back to the original BSC, and the original BSC transmits the user plane voice to the original BTS, resulting in Abis port and A. Waste of interface transmission resources; 2) For calls belonging to different BTSs under the same BTS cluster, the user plane voice of the calling party is transmitted to the control BTS of the BTS cluster through the Abis port of the BTS, and the control BTS of the BTS cluster passes the Abis port again. The user plane voice is transmitted to the BSC, and the BSC transmits the user plane voice to the MGW. The MGW then transmits the user plane voice back to the original BSC, and the original BSC transmits the user plane voice to the control BTS of the original BTS cluster, and the original BTS cluster. Controlling the BTS to transmit the user plane voice to the original BTS, causing the BTS cluster to control the waste of the Abis interface transmission resource between the BTS and the BSC, and also waste the A interface transmission resource;

3) For calls belonging to the same BSC, the BSC first transmits the user plane voice to the MGW, and the MGW transmits the user plane voice back to the original BSC, resulting in waste of the A interface transmission resources. As shown in Figure 2, the user plane voice 1 sent by the MS1 is sent by the BSS to the MGW in the core network, and then returned by the MGW to the BSS, and then sent by the BSS to the MS2; the user plane voice 2 sent by the MS2 is similar.

Summary of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a avoidable

Abis port and A interface transmit resource waste call forwarding method within BSS and mobile communication system.

In order to solve the above technical problem, the present invention provides a call handover method in a base station system, including:

After receiving the internal handover request message sent by the base station controller BSC, the mobile switching center MSC sends an internal handover command message to the BSC;

If the BSC learns that the first call corresponding to the internal handover command message forms a local call with the second call in the BSC after the handover, after the internal handover command message is received, it is established to not pass through the core. The network transmits an internal channel of the user plane voice of the first call and the second call between the users of the first call and the second call, and completes a subsequent handover operation.

Further, the above method may also have the following features:

After receiving the internal handover request message and sending the internal handover command message, the method further includes:

The MSC determines that the first call corresponding to the internal handover request message is after the handover No, the second call in the BSC constitutes a local call, and if yes, the internal call command message carries a local call identifier for identifying the second call;

The BSC learns that the first call corresponding to the internal handover command message forms a local call with the second call in the BSC after the handover: the BSC learns that the first call is switching according to the local call identifier The local call is then made up with the second call.

Further, the above method may also have the following features:

The local call identifier includes:

a circuit identification number of the second call, or a call identifier of the second call. Further, the above method may also have the following features:

The step of the BSC establishing the internal channel includes:

The BSC selects a voice coding mode for the first call, and compares voice coding modes of the first call and the second call:

If the voice coding modes of the first call and the second call are mutually compatible, the BSC establishes a user plane that directly transmits the first call and the second call between users of the first call and the second call. The internal channel of speech;

If the voice coding manners of the first call and the second call are incompatible, and the codec unit is included in the BSC, voice coding for the first call or the second call is set in the internal channel The codec unit that performs the conversion.

Further, the above method may also have the following features:

In the step of the BSC completing the subsequent switching operation:

After receiving the handover complete message sent by the target base station BTS, the BSC removes the connection between the first call and the second call for transmitting user plane voice on the A interface, and sends a handover complete message to the MSC. ;

After receiving the handover complete message, the MSC removes the connection between the first call and the second call on the A interface for transmitting user plane voice.

Further, the above method may also have the following features:

Sending, by the BSC, a handover complete message to the MSC, including local call local exchange completion Indicator

The local call local exchange completion indicator is for identifying whether the internal channel has been used for transmission of user plane voice of the first call and the second call.

Further, the above method may also have the following features:

Before the internal handover request message is sent, if the BSC learns that the first call forms a local call with the second call in the BSC after the handover, in the step of transmitting the internal handover request message,

And the BSC adds a local call local exchange indicator to the internal handover request message, where the indicator is used to notify the MSC to use the internal channel to perform the first call and after the first call handover is completed. The transmission of the user's face voice of the second call.

Further, the above method may also have the following features:

In the step of the MSC sending an internal handover command message to the BSC,

The MSC joins a local exchange indicator in the internal handover command message, the indicator being used to inform whether it is desired to use the internal channel to transmit the user plane voice of the first call and the second call.

In order to solve the above technical problem, the present invention provides a base station controller BSC, including a sending message module and an internal channel module, wherein:

The sending message module is configured to send an internal handover request message to the mobile switching center MSC, so that the MSC sends an internal handover command message to the BSC after receiving the internal handover request message sent by the BSC;

The establishing an internal channel module is configured to: after receiving the internal handover command message, if the first call corresponding to the message forms a local call with the second call in the BSC after the handover, establishing The network transmits an internal channel of the user plane voice of the first call and the second call between the users of the first call and the second call, and performs the first call and the second call using the internal channel User plane voice transmission.

In order to solve the above technical problem, the present invention provides a base station system, and the base station system includes the above BSC.

A mobile communication system, comprising a base station system, a mobile switching center MSC; the base station system Contains BSC, where:

The MSC is configured to send an internal handover command message to the BSC after receiving the internal handover request message sent by the BSC;

The BSC is configured to: after receiving the internal handover command message, if the first call corresponding to the message forms a local call with the second call in the BSC after the handover, establishing, for not using the core network Transmitting an internal channel of the user plane voice of the first call and the second call between the users of the first call and the second call, and using the internal channel to perform user plane voice of the first call and the second call Transmission.

Further, the above system may also have the following features:

The MSC is further configured to: after receiving the internal handover request message, before sending the internal handover command message, determining whether the first call corresponding to the internal handover request message is in the BSC after the handover The second call constitutes a local call, and if so, the internal handover command message carries a local call identifier for identifying the second call.

In summary, the method and system of the present invention establishes an internal channel for transmitting user plane voice without passing through the core network in the BSS, so that after completing the call handover in the BSS, the user who constitutes the call of the local call is used. The voice can be directly transmitted without the MGW of the core network, which avoids the waste of the transmission resources of the Abis port and the A interface. BRIEF abstract

1 is a call switching flow diagram in a BSS (including BSC and BTS) in a conventional GSM system;

2 is a schematic diagram of performing user plane voice transmission between a mobile terminal, a BSC, and an MGW for a local call belonging to the same BSC in the prior art;

FIG. 3 is a schematic diagram of user plane voice transmission between a mobile terminal and a BSC for a local call belonging to the same BSC after local exchange;

4 is a flow chart of call handover in a BSS (including a BSC and a BTS) in a GSM system according to an embodiment of the present invention; FIG. 5 is a schematic diagram of a data structure of a local call identifier in an embodiment of the present invention; FIG. 6 is a schematic structural diagram of an indicator in an embodiment of the present invention.

Preferred embodiment of the invention

The core idea of the present invention is that the local call local switch (LCLS) is implemented by the BSS (including the BSC and the BTS), that is, the user plane voice of the party that does not pass the local call is directly transmitted through the MGW of the core network. To the other party, as shown in FIG. 3, after the user plane voice 1 sent by the MS1 arrives at the BSS, the BSS does not directly transmit it to the MS2 through the MGW of the core network; the user plane voice 2 sent by the MS2 is similar.

The mobile communication system capable of realizing the local exchange local exchange function in the embodiment of the present invention will be described below.

Each network element entity (e.g., the GSM system) performs a brief description; the connection relationship of each network element entity (i.e., message interaction relationship) will be described in detail later when the method of the present invention is described.

The GSM system of the present invention comprises: BSS, MSC, and BSS including BSC, BTS1 and BTS2. Specifically, the MSC obtains the target BSC for performing call handover according to the internal handover request message sent by the BSC, and the MSC determines whether the corresponding call constitutes a local after the handover, in addition to performing the functions specified by the existing protocol. Call, if yes, add an identifier (hereinafter referred to as a local call identifier) for identifying the local call in the internal handover command message sent to the target BSC, the identifier is used to inform the target BSC of the call that needs to be handed over (may Called as the first call) Which call (which may be referred to as the second call) under the BSC constitutes a local call after the handover.

After receiving the internal handover command message sent by the MSC, the BSC learns, according to the local call identifier in the message, the call that needs to be handed over (the first call) and the call that is under service (the second call) constitute a local call; The BSC establishes a BSS internal channel for the local call local exchange of the two calls. The internal channel can be established inside a BTS, or can be established inside a BTS cluster, or can be established inside a BSC.

After the BSC completes the establishment of the internal channel, and decides to use the local call local switching function, the local call local exchange completion indicator is added to the handover complete message replied to the MSC, and the indicator is used to inform the MSC of the call (first call). Use the local call local exchange feature after the switch is complete.

The BSC and the MSC use the local call local switching function after completing the handover, and remove the handover at the same time. The call (first call) and the connection between the BSC and the MGW of the other party (the second call that has not made the handover) that constitutes the local call with the handover call (first call).

In summary, the BSC of the embodiment of the present invention includes a sending message module and an internal channel module, where:

The method of the present invention and the message interaction relationship between the above network elements will be described in detail below with reference to the accompanying drawings and embodiments.

4 is a flow chart of call switching in a BSS (including BSC and BTS) in the GSM system according to an embodiment of the present invention. As shown in FIG. 4, the process includes the following steps:

401: The MS sends a measurement report to the BTS1, and the BTS 1 forwards the measurement report to the BSC.

402: The BSC sends an Internal Handover Required message to the MSC.

403: After receiving the internal handover request message sent by the BSC, the MSC learns the target BSC that performs the call handover, and determines whether the call (first call) constitutes a local call with the second call after the handover (the specific judgment algorithm belongs to the prior art). If yes, the MSC enters the local call identifier in the Internal Handover Command message sent to the target BSC;

The local call identifier may be: a circuit identification code (CIC) or another party call (second call) of another party call (second call) that can make a local call with the to-be-switched call (first call) Call Identifier (CI).

The above circuit identification number is the existing circuit identifier in the protocol (for the flag bearer in TDM) The A-interface call on the Transport); the above call identifier is the existing Call ID in the protocol (used to mark the A-interface call carried on the IP Transport). When the call is established, the MSC sends the above identifier to the BSC by an assignment message.

Preferably, the local call identifier may be included in a data structure as shown in FIG. 5, the data structure consisting of a Local Call reference ID for TDM (Local Call Reference Identifier for TDM) and a Local Call reference ID for IP (for The local call reference identifier of the IP is composed of two parts. The CIC is included in the Local Call reference ID for TDM part, and the CI includes the Local Call reference ID for IP part. When the other party of the local call is based on TDM transmission on the A interface, the Local Call reference ID for TDM part carries the CIC value, and the CI value of the Local Call reference ID for IP part may be null; and when the other party of the local call is in the A When the interface is based on IP transmission, the Local Call reference ID for IP part carries the CI value, and the CIC value of the Local Call reference ID for TDM part may be null. The representation methods of Circuit Identity Codec and Call Identifier are prior art.

404 ~ 405: The BSC sends a Channel Activation message to the BTS2 of the target cell to activate the channel; after receiving the channel activation message, the BTS2 sends a Channel Activation Acknowledge message to the BSC;

In addition, after receiving the internal handover command sent by the MSC, the BSC can know that the call being handed over (the first call) and the other call represented by the local call identifier (the second call) constitute a local call; therefore, the BSC is completed. In addition to the switching of the wireless channel, an internal channel for transmitting user plane voice is also established in the BSS, and after receiving the user plane voice sent by the MS, the user plane is transmitted between the two users of the local call through the internal channel. voice.

When the internal channel is established, the BSC selects the speech coding mode for the call to be switched, and compares the selected speech coding mode with the other speech coding mode of the call. Six conditions will appear, as shown in Table 1:

4 NYYYN

5 N Y N Y N

6 N N Y N N Table 1

When the first, second, and third cases occur, that is, when the voice coding modes of the two parties are compatible, the BSC2 establishes a transmission channel (internal channel) for directly transmitting the voice of the user's face of the call when establishing the internal channel, that is, The user plane voice of the party on the call is directly transmitted to the other party of the call.

When the fourth and fifth cases occur, that is, when the voice coding methods of the two parties are incompatible, the TC (Trans-coder) needs to be set in the internal channel; when the BSC uses the internal channel, it needs to be received. The voice code of the calling party is converted into the other party's compatible voice coding mode by the TC, that is, the internal channel transmits the user plane voice of the party to the TC in the BSS first, and the TC converts the received user plane voice into another. A compatible encoding method is transmitted to the other party of the call.

When the sixth situation occurs, the local call local exchange function will not be available.

406 - 413: same as steps 106 ~ 113;

414: The MS sends a Handover Complete message to the BTS2, and the BTS2 forwards the handover complete message to the BSC to notify the BSC that the handover is complete.

415: The BSC sends a handover complete message to the MSC.

After the internal channel is established, and the local exchange is used, the local exchange local completion indicator is added to the handover completion message sent to the MSC, and the MSC can learn whether the local call has been locally exchanged by using the local call. The function.

In addition, after receiving the handover complete message sent by the MS through the BTS2, the BSC removes the connection between the BSC and the MGW for transmitting the user plane voice between the two parties (the first call that performs the handover and the second call that does not perform the handover). Receiving, by the MSC, the handover complete message carrying the local exchange local exchange completion indicator, and the indicator indicates that when the local exchange function is used, the two parties are disconnected (the first call for handover and the second call for handover) A connection between the BSC and the MGW for transmitting user plane voice.

Preferably, the local call local exchange completion indicator can be in the format shown in FIG. The local call local exchange completion indicator occupies 8 bits, and the lower bit 1 is used to indicate the status of the local exchange, and other bits can be reserved. Specifically, bit 1 can be used to indicate whether the local call local exchange function is used after the handover is completed, see Table 2:

Table 2

That is to say, when the value of bit 1 is 1, it indicates that the call has used the local switching function. When the value of bit 1 is 0, it indicates that the call does not use the local switching function.

According to the core idea of the present invention, the foregoing embodiment has various transformation manners, for example: If the internal handover request message is sent in step 402, the BSC knows that the to-be-switched call (first call) is after the handover with the BSC. A certain call (second call) constitutes a local call. For example, before the handover, the BSC has learned that the call is a local call during the call setup process, and may add a local call local to the internal handover request message. Exchanging an indicator, informing the MSC that the handover call (first call) will use the local call local exchange function after the handover; in this case, the local handover command message sent by the MSC to the BSC may not join the local call Identifier

Optionally, in order to explicitly inform the BSC whether the MSC wants to use the local switching function for the local call, the MSC may add a local exchange indicator to the handover request message sent to the BSC, where the indicator is used to inform the BSC whether it wants to This local call uses the local exchange feature. The indicator can be in the format shown in Figure 6, where the local exchange indicator occupies 8 bits and the lower bit 1 is used to indicate whether it is desirable to use the local call local exchange function, and other bits can be reserved. The value of bit 1 is shown in Table 3:

table 3 While the invention has been described in connection with the specific embodiments, the modifications and the modifications Such modifications and variations are considered to be within the scope of the invention and the scope of the appended claims.

Industrial applicability

The present invention provides a call handover method and a mobile communication system in a base station system,

An internal channel for transmitting user plane voice without passing through the core network is established in the BSS, so that after the call switching in the BSS is completed, the user plane voice of the call constituting the local call can be directly transmitted without passing through the MGW of the core network, avoiding the Abis port. The waste of transmitting resources with the A interface.

Claims

Claim

A call handover method in a base station system, comprising:

If the BSC learns that the first call corresponding to the internal handover command message is after the handover and the

The second call in the BSC constitutes a local call, and after receiving the internal handover command message, establishing, for transmitting the first call between users of the first call and the second call without going through the core network The internal channel of the user's voice of the second call, and the subsequent switching operation is completed.

2. The method of claim 1 wherein:

Determining, by the MSC, whether the first call corresponding to the internal handover request message forms a local call with the second call in the BSC after the handover, and if yes, carrying the identifier in the internal handover command message a local call identifier of the second call;

The BSC learns that the first call corresponding to the internal handover command message is after the handover and the

The second call in the BSC constitutes a local call: the BSC learns from the local call identifier that the first call forms a local call with the second call after the handover.

3. The method of claim 2, wherein:

The local call identifier includes:

a circuit identification number of the second call, or a call identifier of the second call.

4. The method of claim 1 wherein:

The step of the BSC establishing the internal channel includes:

If the voice coding modes of the first call and the second call are mutually compatible, the BSC establishes that the first call and the second call are directly transmitted between users of the first call and the second call. The internal channel of the user's face voice;

5. The method of claim 1 wherein:

In the step of the BSC completing the subsequent switching operation:

After the MSC receives the handover complete message, the first call and the second call are removed.

The A interface is used to transmit the connection of the user's voice.

6. The method of claim 5, wherein:

Sending, by the BSC, the handover completion message to the MSC, including a local call local exchange completion indicator;

7. The method of claim 1 wherein:

8. A method according to any one of claims 1 to 7, wherein:

In the step of the MSC sending an internal handover command message to the BSC,

The MSC joins a local exchange indicator in the internal handover command message, the indicator is used for Notifying whether it is desirable to use the internal channel to perform transmission of user plane speech for the first call and the second call.

9. A base station controller BSC, comprising: transmitting a message module and establishing an internal channel module, wherein:

10. A base station system, the base station system comprising the BSC of claim 9.

A mobile communication system comprising a base station system and a mobile switching center MSC; said base station system comprising a BSC, wherein:

12. The system of claim 11 wherein: