CN100401807C

CN100401807C - Creation for shared link in digit group system

Info

Publication number: CN100401807C
Application number: CNB2004100917271A
Authority: CN
Inventors: 罗雄; 吕莎; 尧俊峰; 符子建; 冯成林
Original assignee: Huawei Technologies Co Ltd
Current assignee: Global Innovation Polymerization LLC; Gw Partnership Co ltd
Priority date: 2004-11-25
Filing date: 2004-11-25
Publication date: 2008-07-09
Anticipated expiration: 2024-11-25
Also published as: CN1780424A

Abstract

The present invention discloses a method for establishing a shared link in a digital cluster system. The method comprises: a) after receiving an establishing request of a cluster call, a wireless access network (RAN) judges that whether the current call is the first time call in the current call cluster group; if yes, a link is established for the current call, and the current processing is ended; otherwise, step b is performed; b) the wireless access network judges that whether the cluster group establishes a link; if yes, the information of the current call is added in the information of the established link, and the current processing is ended: otherwise, the current call is cached; c) the wireless access network judges that if the current link is established successfully or not; the cached call information is added to the successfully established link information; if failing, the wireless access network releases the current cached call. The method of the present invention can reduce loss probability and avoid the repetition establishment of the shared link, and accordingly the present invention improves the quality of service.

Description

Method for establishing shared link in digital cluster system

Technical Field

The invention relates to a service link realization technology in a digital cluster system, in particular to a shared link establishment method in the digital cluster system.

Background

At present, Push-to-Talk (PTT) services, which are applied to team, workgroup, and group cooperative work and communication, refer to real-time point-to-point and point-to-multipoint voice communications. The service adopts a half-duplex mode, namely only one person can talk at the same time, a calling party can initiate a conversation to one person or one group only by pressing a special key, and the conversation is immediately connected without dialing and waiting for the other party to be off-hook, so that a talk group is quickly established.

When digital trunking service is implemented in CDMA, CDMA 2000 or CDMA 1X systems, trunking service data is transmitted over a packet network, and a mobile terminal (MS) interacts with the packet network for signaling and data through a Radio Access Network (RAN). In order to enable the transfer of data between the RAN and the packet network, data links need to be established between entities within the RAN and between the RAN and packet network entities during the signaling interaction for call setup. Within the RAN, entities related to handling the trunking services mainly include: a Base Station Controller (BSC) and a Packet Control Function (PCF) entity; and the functional entity related to the trunking service processing on the packet network is a PTT server (PS, PTTServer). The BSC is responsible for receiving the signaling and data from the MS side and packaging the signaling and data into packet data packets, sending the packet data packets to the PCF, and meanwhile, receiving the packet data packets from the PCF, assembling the packet data packets into service frames and distributing the service frames to each MS; the PCF is responsible for processing the signaling and data of the packet data service and integrally managing and controlling the data link; the PS is used as a control center of the trunking service to control the trunking service call and is responsible for the work of media stream distribution and the like.

Because the trunking service adopts a half-duplex communication mode, only one person can talk at the same time, and in order to realize one person talking and multiple persons listening, the voice data of the speaker needs to be sent to the PS specially processing the trunking service, and the PS distributes the voice data to each listener through the RAN. In this way, in the conversation in the same cluster group, the data transmitted on the reverse link from the talker MS to the PS and the respective forward links from the PS to the listener MSs are the same. Therefore, to save link resources and speed up call setup, the RAN will establish a shared link for calls of the same trunking group when receiving the trunking call.

In the existing process of establishing a cluster call shared link, after a cluster call establishment request received by a BSC in a RAN, judging: whether the current call is the first cluster call establishment request of the cluster group under the BSC or not, if so, the BSC interacts with the PCF, allocates a new A8 link identifier, and establishes an A8 link; otherwise, adding the current call information to the A8 link information established by the BSC for the cluster group; and, the PCF in the RAN, after receiving the A8 link setup request, determines: whether the current call is a first A8 link establishment request of the cluster group, if so, the PCF interacts with the PS, allocates a new GMP link identification, and establishes a GMP link; otherwise, adding the current call information to the GMP link information established by the PCF for the cluster group.

When the BSC and the PCF establish a new A8 link, the BSC sends an A8 link establishment request to the PCF, for example, an A9 establishes an A8 message A9-Setup-A8, and the A8 link is not successfully established until the BSC successfully receives an A8 link connection response returned by the PCF, for example, an A9 connects the A8 message A9-Connect-A8, and if the BSC does not receive the A9-Connect-A8 message within a specified time, the A8 link is not successfully established.

Thus, problems arise when multiple users of the same cluster group initiate call setup requests simultaneously. Such as: after the BSC sends A9-Setup-A8 to PCF for the first call of the cluster group, when the message of A9-Connect-A8 returned by PCF is not received, the BSC receives the second call establishment request of the cluster group, at this time, the BSC decides not to establish A8 link for the second call establishment request, and the second call shares the same A8 link with the first call; however, if the BSC does not receive the a9-Connect-A8 message corresponding to the first call within the specified time, indicating that the A8 link for the first call is not successfully established, the second call and the subsequent calls of the trunking group will not have available links, which will result in a large call loss for the trunking group.

The prior art also provides another method for establishing a shared link of a trunking call, which is similar to the above shared link establishment process, except that the determination is: the BSC judges whether the BSC successfully establishes an A8 link for the current call set group; the PCF determines whether it has successfully established a GMP link for the current paging group.

Problems also arise when a group call is established using this shared link establishment method. Such as: when the BSC sends A9-Setup-A8 to the PCF for the first call of the cluster group, and when the A9-Connect-A8 message returned by the PCF is not received, the BSC receives the second call establishment request of the cluster group, at the moment, because the BSC does not successfully establish an A8 link for the cluster group, the BSC decides to establish an A8 link for the second call; but then if the BSC receives the a9-Connect-A8 message for the first call within the specified time, indicating that the A8 link for the first call was successfully established, the second call, and possibly even subsequent calls for the group, will have begun establishing the A8 link. Thus, the BSC will repeatedly establish A8 link for the calls of the same trunking group, and link sharing of the trunking call cannot be really realized, which wastes system link resources.

Similar problems as described above in the A8 link setup procedure also arise when establishing a GMP link between a PCF and a PS.

Therefore, in the existing method for establishing the shared link in the digital trunking system, when a plurality of trunking calls are established in a centralized manner, a large amount of call loss or repeated establishment of the shared link is easily caused, the trunking service quality is seriously affected, and system resources cannot be effectively utilized.

Disclosure of Invention

In view of the above, the main objective of the present invention is to provide a method for establishing a shared link in a digital trunking system, which can ensure that each call of a trunking service has an available link and avoid repeated establishment of the shared link, thereby improving service quality and saving link resources.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

the invention discloses a method for establishing a shared link in a digital cluster system, which comprises the following steps:

after receiving the cluster call establishment request, the RAN judges whether the current call is the first call of the current call cluster group, if so, establishes a link for the current call, and ends the current processing; otherwise, executing the step b;

b. judging whether the cluster group establishes a link, if so, adding current call information in the information of the established link, and ending the current processing; otherwise, caching the current call;

c. judging whether the current link is successfully established or failed, if so, adding the cached call information into the information of the successfully established link; if the call fails, the currently cached call is released.

In step c, before releasing the current buffered call, the method further includes:

c1. judging whether the link establishment frequency reaches a preset link establishment frequency threshold or not, if so, releasing the cached residual calls and ending the current processing; otherwise step c2 is performed.

c2. Extracting a call from the cached calls, establishing a link for the call, and recording the link establishment times;

c3. judging whether the link establishment is successful or unsuccessful in the step c2, and if the link establishment is successful, adding the cached remaining call information into the information of the successfully established link; if it fails, return to step c1.

Wherein the established link is: a GMP link between the PCF in the RAN and an external PS;

in the step a: the cluster call establishment request received by the RAN is an A8 link establishment request received by the PCF; the judgment is as follows: the PCF judges whether the current call is a first A8 link establishment request of the cluster group; alternatively, it is determined whether the current call is the first A8 link establishment request for the cluster group under the BSC of the current call.

Wherein the established link is: an A8 link between the BSC and PCF within the RAN;

in the step a: the cluster call establishment request is a cluster call establishment request received by the BSC; the judgment is as follows: the BSC judges whether the current call is a first cluster call establishment request of the cluster group under the BSC.

Wherein, when establishing the A8 link, the method further comprises: the PCF establishes a GMP link with the PS for the call currently requesting establishment of the A8 link.

Wherein, when establishing the A8 link, the method further comprises:

PCF judges whether the A8 link requested to be established currently is the A8 link requested to be established for the first time by the cluster group, if so, the PCF and the PS establish a GMP link for the call requesting to establish the A8 link currently, and the current processing is finished; otherwise, executing step b 11;

b11.PCF judges whether GMP link is established for the cluster group, if yes, current calling information is added in the information of GMP link corresponding to the cluster group, and current processing is finished; otherwise, caching the current call information;

the PCF judges whether the current GMP link establishment is successful or failed, if so, the cached calling information is added into the information of the successfully established GMP link; if the call fails, the currently cached call is released.

In step c11, before releasing the currently buffered call, the method further includes:

c111. judging whether the GMP link establishment times reach a preset link establishment time threshold or not, if so, releasing the cached residual calls and ending the current processing; otherwise step c112 is performed.

c112. Extracting a call from the cached calls, establishing a GMP link for the call, and recording the establishment times of the GMP link;

c113. c112, determining whether the GMP link establishment is successful or unsuccessful, and if successful, adding the cached remaining call information to the information of the successfully established GMP link; if not, return to step c111.

The method for judging whether the GMP link establishment is successful or failed is as follows: PCF judges whether the current established GMP link is successful or failed according to whether the GMP link establishment confirmation message returned by PS is received within the time specified by the protocol and the reason value carried by the message indicates that the link establishment is successful; or,

PCF receives GMP link establishment confirmation message from PS in the time specified by the protocol, and the reason value carried by the message indicates that the link establishment is successful, and judges that the current GMP link establishment is successful; and judging that the current GMP link establishment fails according to a GMP link establishment confirmation message from the PS and the reason value carried by the message indicates that the link establishment fails.

The method for judging whether the link establishment of the A8 is successful or failed comprises the following steps: the BSC judges whether the currently established A8 link is successful or failed according to whether an A8 link connection response returned by the PCF is received within the time specified by the protocol; or,

the BSC judges that the current A8 link is successfully established according to the A8 link connection response received from the PCF within the time specified by the protocol; and according to the A8 link release completion message from the PCF, judging that the current A8 link establishment fails.

The key point of the invention is that: when establishing a shared link, if a current call is called for a first time by a non-cluster group and a link is not successfully established for the cluster group by the RAN, caching the call; then, when the cluster group successfully establishes the link, the call information cached by the cluster group is added to the link information which is successfully established, and when the cluster group fails to establish the link, the link is established for the call cached by the cluster group.

Therefore, the method for establishing the shared link in the digital trunking system can avoid the repeated establishment of the shared link and can ensure that the trunking group calls an available link when the shared link exists, thereby really realizing that the calls of the same trunking group share one service link, greatly reducing the call loss rate and effectively utilizing system resources to realize high-quality trunking service.

Drawings

FIG. 1 is a flow chart illustrating a preferred embodiment of the process for establishing a shared A8 link according to the present invention;

FIG. 2 is a flowchart illustrating a preferred embodiment of the call setup A8 link buffering in FIG. 1;

fig. 3 is a flowchart illustrating a preferred embodiment of establishing a shared GMP link according to the present invention;

fig. 4 is a flow chart illustrating a preferred embodiment of the process for call setup GMP link buffering in fig. 3.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

The method for establishing the shared link in the digital cluster system can be applied to the establishment process of a shared A8 link and/or a shared GMP link, wherein the shared A8 link is established for the call of the same cluster group under the same BSC, and the shared GMP link is established for the call of the same cluster group under the same PCF. The A8 and/or GMP shared link establishment procedure of the method of the present invention is described in detail below with reference to the drawings.

Fig. 1 is a process flow diagram illustrating a preferred embodiment of establishing a shared A8 link in the method of the present invention. The A8 link is a service link between BSC and PCF, and BSC mainly includes call control unit (CC) and resource management unit (RM); when a call is established, the CC is responsible for signaling processing of a call flow, receives/sends a call establishment request, sends a resource application/release request to the RM, performs message interaction with an external entity, stores cluster group identification and user information in the CC, and the RM is responsible for distributing and managing service processing resources and A8 link resources and stores cluster group information. As shown in fig. 1, the A8 link establishment procedure is completed by the CC, RM, and PCF in the BSC, and the specific processing steps include:

step 101: and after receiving the cluster call establishment Request of the MS, the CC sends a Resource application Request to the RM. Here, the trunking call setup Request may be an origination Request, a paging response, or a group call joining Request, and the trunking call setup Request and the resourcepamount Request message include: cluster group identification, user identification, and the like.

Step 102: the RM reads the cluster group identifier in the Resource application Request message in step 101, and determines whether the currently received cluster call establishment Request is the first cluster call establishment Request of the cluster group under the BSC where the RM is located according to the cluster group information stored by the RM, and if so, executes step 106; otherwise step 103 is performed.

Step 103: the RM judges whether the BSC has already set up A8 link for the cluster group according to the cluster group information stored by the RM, if so, the step 104 is executed; otherwise step 105 is performed.

Here, as can be seen from the background art, when establishing a shared link of a trunking service, based on the trunking group information stored in the BSC, the BSC may know whether a current call is a first call establishment request of the trunking group and whether an A8 link has been established for the trunking group, and the PCF may also know whether a current call is a first A8 link establishment request of the trunking group and whether a GMP link has been established for the trunking group, and therefore, the specific determination method is not described in detail herein.

Step 104: adding current call information to the established A8 link information of the cluster group stored by the current call information, such as: adding the user of the current call in the user information corresponding to the A8 link established by the cluster group, so that the current call shares the A8 link; and returns a Resource applyconfirrm message to the CC indicating that the CC does not need to establish a new A8 link for the cluster group, ending the current process.

Step 105: and caching the current call information and ending the current processing. The BSC will process the cached call information accordingly after receiving the result of the link establishment of cluster group A8. Here, the cached call information includes: cluster group identification, user identification, etc.

Wherein the call information is typically stored as a first-in-first-out queue for ease of call setup management. There are various ways of caching, such as: opening up a static calling information array according to the number of the users of the cluster group for caching calling information; or, dynamically caching the call information in a linked list form, and the like, and which call information caching mode is specifically adopted is related to the implementation condition of the system and the cluster group scale, which is not limited in the present invention.

Step 106: the RM returns a Resource Apply Confirm message to the CC instructing the CC to establish an A8 link for the cluster group, so that the CC sends an a9-Setup-A8 message to the PCF connected to the BSC requesting to establish an A8 link.

Here, the method for indicating whether the CC establishes an A8 link for the cluster group through the Resource application Confirm message may include: first, the message is indicated by filling an invalid or valid A8 link identifier (A8 Traffic ID), and second, a flag bit is set in the message to indicate, and the like, and specific indication methods are various, and the present invention is not limited thereto.

As can be seen from fig. 1, when the BSC receives a group call, if the current call is the first call setup request of the group under the BSC, the BSC sends an A8 link setup request to the PCF, thereby starting to set up an A8 link for the current call; if the current call is not the first call setup request and the BSC has successfully established an A8 link for the group, the current call will share the established A8 link; if the current call is not the first call establishment request and the BSC has not successfully established an A8 link for the cluster group, the BSC caches the current call information until learning the result of establishing an A8 link for the cluster group, and processes the cached call.

Fig. 2 is a flow chart illustrating the call setup A8 link buffered in fig. 1 according to an embodiment. As shown in fig. 2, when the link establishment of A8 is successful, steps 201 to 205 are executed; when the link establishment of A8 fails, steps 201 'to 205' are performed.

When the link establishment of the A8 is successful, the specific processing includes:

step 201 to step 202: the PCF returns an A9-Connect-A8 message to the CC after allocating resources for the A8 link, and the CC sends a Resource confirmation Request Resource Affirm Request to the RM

Step 203 to step 204: after receiving the resourcesaffirm Request message in step 202 within a specified time, if it indicates that the current A8 link is successfully established, the RM adds the cluster group call information that is cached by itself to the newly established A8 link information, for example: user information, etc., so that the cluster group call cached by the RM may share the A8 link. Meanwhile, the RM returns a Resource acknowledgement confirmation Resource Affirm Confirm message to the CC to complete the A8 link establishment process.

When the BSC establishes an A8 link, timing is started by sending an A8-Setup-A9 message to the PCF, and if the A9-Connect-A8 message returned by the PCF is received within the time specified by the protocol, the current A8 link is successfully established; otherwise, the A8 link establishment is failed. Therefore, the BSC typically starts a timer when sending the A8-Setup-a9 message, the timeout threshold of which is set to the duration of the time specified by the protocol, and can decide that the A8 link Setup is successful if the BSC receives the a9-Connect-A8 message before the timer times out; otherwise, decision A8 fails the link setup. The timer is usually started by a CC, the CC sends a Resource Affirm Request message to the RM when judging that the link establishment of A8 is successful, and sends a Resource release Request message to the RM when judging that the link establishment of A8 is failed.

Here, in order to determine whether to successfully receive the message sent by the CC, the RM also needs to start a timer when sending a Resource applyconfirrm message, the duration of the timer is determined according to the internal implementation condition of the BSC, and if the RM receives a Resource Affirm Request message before the timer expires, it may determine that the link establishment of the A8 link is successful; otherwise, judging that the link establishment fails at A8, or judging that the link establishment fails at A8 when a Resource Release Request message is received.

In addition, a timer may be set in the RM only, and whether the link establishment of the A8 is successful may be determined according to whether a Resource Affirm Request message from the CC is received before the timer expires. The specific implementation of which timer is adopted is not a problem to be solved by the present invention, and is not described in detail herein.

Step 205: the RM returns a Resource Apply Confirm message to the CC, replies to the CC with a Resource Apply Request message previously sent by the CC, and indicates that the CC need not establish an A8 link for the cluster group.

The messages in the above steps 201, 202, and 204 are related to the first call setup of the trunking group, and the messages in the steps 203 and 205 are related to the processing of the currently cached trunking group call. Therefore, the Resource application Confirm message returned in step 205 should correspond to the currently cached group call one-to-one, and the RM will return the Resource application Confirm message for each cached call in turn.

When the link establishment of the A8 fails, the specific processing includes:

step 201 '-step 202': when the link establishment of the A8 fails, the PCF returns an A8 link Release completion message to the CC, for example, the A9 Release A8 completes the A9-Release-A8 Complete message, and the message carries information such as the A8Traffic ID of the currently failed A8 link, thereby indicating that the current link establishment of the CC fails at the A8. The CC sends a Resource Release Request message to the RM, and the message also carries the information of the cause value, A8Traffic ID and the like in the A9-Release-A8 Complete message in the step 201'.

Step 203': the RM releases the A8Traffic ID stored by itself according to the received Resource Release Request message, thereby releasing the A8 link Resource, and returns a Resource Release Confirm message to the CC, completing the Resource Release of the failed A8 link.

Because, if the RM does not receive the Resource Affirm Request message within the specified time, it may also determine that the current A8 link establishment fails, therefore, the RM may start a timer when sending the Resource Apply Confirm message, the timeout threshold of the timer is set to the duration of the specified time, and if the RM does not receive the Resource Affirm Request message before the timer expires, which indicates that the current A8 link establishment fails, the RM is directly triggered to execute the above step 203'.

Steps 204 'to 205': the RM knows according to the cause value in the Resource Release Request message in step 202', this is the A8 link Release Request triggered by the A8 link establishment failure, so extracts a call from the call information buffered by itself, sends a Resource Apply confirm message to the CC according to the call information, replies to the CC with the Resource Apply Request message sent by the CC for the call previously, and indicates the CC to start establishing the A8 link through the message, the CC sends a9-Setup-A8 to the PCF, and establishes an A8 link for the call.

Then, the BSC decides to add the remaining call information buffered by itself to the successfully established A8 link information, or to extract the buffered next call to establish an A8 link for the call, or to release the remaining call information buffered by itself, according to the learned result of the A8 link establishment, as described in fig. 2.

Here, a threshold of A8 link establishment times may be preset, an initial value of the A8 link establishment times is set to zero, before each time of extracting the cached call, it is determined whether the number of times of establishing the A8 link for the cached call reaches the threshold of the link establishment times, if so, the BSC will release the cached remaining call information, and end the trunking call establishment process; otherwise, a call is fetched from the cache, an A8 link is established for the call, and the number of times the A8 link is established is recorded. Thus, before the step 204', further comprising: judging whether the A8 link establishment frequency reaches the set link establishment frequency threshold, if so, releasing the current cached call and ending the current processing; otherwise, go to step 204'.

In this embodiment, when the A8 link of the first call of the cluster group fails to be established, the BSC will continue to establish one or more A8 links for the buffered calls, which can minimize call loss, but will make the delay of the cluster call establishment too long and occupy a large amount of system resources. The invention also provides another implementation mode: if the A8 link setup of the first call of the cluster group fails, the BSC releases all the calls buffered by itself and notifies the cluster group user to reinitiate the call setup request, and then the steps 204 'and 205' do not need to be executed. By adopting the method, the cluster call establishment time delay is shorter, and the system resources are saved. Here, when the RM releases the cached call, the RM carries a cause value indicating that the A8 link establishment fails in a resourcepapply Confirm message returned to the CC, indicating that the CC: the MS is notified of the call setup failure without establishing an A8 link.

The messages in the above steps 201 ', 202', 203 'are messages related to the first call setup of the cluster group, and the messages in step 204' are processes for the currently cached call of the cluster group. Therefore, when the RM is releasing the buffered calls, the resource apply Confirm message returned in step 204' corresponds to the currently buffered group call one by one, and the number of the messages is the same as the number of the buffered calls.

When the method is applied to the establishment of the shared GMP link, the process is basically the same as the establishment process of the shared A8 link. Fig. 3 is a flow chart illustrating a preferred embodiment of the process for establishing a shared GMP link according to the present invention. As shown in fig. 3, the method specifically comprises the following steps:

step 301: after receiving the a9-Setup-A8 message sent by the BSC, the PCF determines whether the a9-Setup-A8 message is the first A8 link establishment request of the current calling trunking group, if yes, executes step 302; otherwise step 303 is performed.

Step 302: the PCF sends a GMP Link Setup Request message to the PS, thereby setting up a GMP Link for the current call and ending the current processing.

Step 303: the PCF judges whether the PCF establishes a GMP link for the cluster group according to the cluster group information stored by the PCF, if so, the step 304 is executed; otherwise, step 305 is performed.

Step 304: adding current call information to the established GMP link information of the cluster group stored by the GMP node, such as: the newly assigned A8Traffic ID of the PCF or BSC is added to the information of the GMP link established by the cluster group, so that the GMP link can be shared by the A8 link that is currently requested to be established, and the current process is ended.

Step 305: and caching the current call information and ending the current processing. The BSC will perform corresponding processing on the cached call information after learning the GMP link establishment result of the cluster group. Here, the cached call information includes: cluster group identification, A8Traffic ID, etc.

As can be seen from fig. 3, when the PCF receives the trunking call, if the current call is the first A8 link establishment request of the trunking group under the PCF, the PCF sends a GMP link establishment request to the PS, thereby starting to establish a GMP link for the currently requested A8 link; if the current call is not the first A8 link establishment request and the PCF has successfully established a GMP link for the cluster group, the currently requested established A8 link will share the established GMP link; if the current call is not the first A8 link establishment request and the PCF has not successfully established a GMP link for the cluster group, the PCF caches the current call information until the result of establishing the GMP link for the cluster group is known, and processes the cached call.

The process described above with reference to fig. 3 is applied to group call setup, so that all calls in the same group under the same PCF can share the same GMP link. In the actual networking process of the trunking system, usually one PCF is connected with one or more BSCs, so the PCF may also establish a shared GMP link only for calls of the same trunking group under the same BSC according to the needs of system implementation. The process of establishing such a shared GMP link is substantially the same as that shown in fig. 3, except that: the determination in step 301 is that the PCF determines, according to the BSC identifier in the A8 link establishment request, whether the a9-Setup-A8 message is the first A8 link establishment request of the cluster group under the BSC.

Fig. 4 is a flow chart illustrating a preferred embodiment of the process for call setup GMP link buffering in fig. 3. As shown in fig. 4, when the GMP link establishment is successful, step 401 and step 402 are performed; when the GMP link establishment fails, steps 401 'and 402' are performed.

When the GMP link establishment is successful, the specific processing includes:

step 401: the PS allocates resources for the GMP Link and then returns a Link Setup confirmation Confirm message to the PCF, and the message carries information of reason values such as successful Link Setup and the like, which indicates that the current GMP Link is successfully established.

Step 402: after receiving the Link setup confirm message in step 401 within the time specified by the protocol, the PCF determines that the current GMP Link establishment is successful, and adds the cluster group call information cached by itself to the newly established GMP Link information, for example: a8Traffic ID, etc., so that the cluster group call cached by the PCF may share the GMP link.

Here, the PCF starts a timer when sending the Link Setup Request, the timeout threshold of the timer is set to the duration of the time specified by the protocol, if a Link Setup Confirm message is received before the timer expires and the message carries the cause value, such as successful Link Setup, etc., it is determined that the cluster group has successfully established the GMP Link, and the message triggers the A8 Link requested to be established by the cluster group cached by the PCF to share the successfully established GMP Link.

When the GMP link establishment fails, the specific processing includes:

step 401': when the GMP Link fails to be established, the PS returns a Link Setup Confirm message to the PCF, and the message carries the reason values such as the Link establishment failure and the GMP Link identification which fails to be established currently, so as to indicate the current GMP Link establishment failure of the PCF.

Step 402': the PCF learns, according to the cause value in the Link Setup Confirm message in step 401', that the message is a GMP Link Setup Confirm message triggered by a GMP Link Setup failure, so that an A8 Link message requesting Setup is extracted from call information buffered by the PCF, and a Link Setup Request message is sent to the PS according to the A8 Link message to set up a GMP Link for the A8 Link requested to be Setup.

In addition, if the PCF does not receive the Link Setup Confirm message within the protocol specified time, it may also determine that the current GMP Link Setup fails, therefore, the PCF may start a timer when sending a Link Setup Request, the timeout threshold of the timer is set to the duration of the protocol specified time, if the PCF does not receive the Link Setup Confirm message carrying information that the cause value is Link Setup success, etc. before the timer expires, indicating that the GMP Link Setup fails, the PCF directly triggers step 402'.

Then, the PCF determines, as described in fig. 4, whether to add the remaining call information buffered by itself to the GMP link information successfully established, to establish a GMP link for the next buffered call, or to release the remaining call buffered by itself, according to the result of the GMP link establishment.

Here, a threshold of the number of times of establishing the GMP link may be preset, an initial value of the number of times of establishing the GMP link is set to zero, before each time of extracting the cached call, it is determined whether the number of times of establishing the GMP link for the cached call reaches the threshold of the number of times of establishing the link, if so, the PCF releases the cached remaining call information, and ends the trunking call establishment process; otherwise, a call is extracted from the cache, a GMP link is established for the call, and the establishment times of the GMP link are recorded. Thus, before the step 402', the method further comprises: judging whether the GMP link establishment times reach a set link establishment time threshold, if so, releasing the current cached call and ending the current processing; otherwise, step 402' is performed.

In this embodiment, when the first GMP link establishment of the cluster group fails, the PCF continues to establish one or more GMP links for the cached call, and as in the establishment process of the A8 link, in order to shorten the delay of the cluster call establishment and save system resources, the PCF may also release all the cached calls when the first GMP link establishment of the cluster group fails, and return a message of the call establishment failure to the cluster group user through the BSC, so that the user re-initiates the call establishment request, and then the step 402' does not need to be executed.

While the above-mentioned fig. 1 to fig. 4 respectively describe the establishment procedures of the shared A8 link and the shared GMP link in the method of the present invention, the present invention may also combine the methods of fig. 1 to fig. 4 to simultaneously establish the shared A8 link and the shared GMP link. That is to say: the CC in the BSC receives the group call setup request, i.e., starts executing the process described in fig. 1 and 2, and the PCF receives the A8 link setup request, and then starts executing the process described in fig. 3 and 4, so that the RAN and PS can establish a shared A8 link for calls in the same group under the same BSC and a shared GMP link for A8 link in the same group under the same PCF.

Here, since the shared A8 link is established for the same cluster group user under the same BSC, when the PCF receives the A8 link establishment request, the GMP link is not necessarily established for the cluster group under the BSC, and therefore, when the networking mode of the system is that one PCF corresponds to one BSC, or the shared GMP link needs to be established for the call of the same cluster group under the same BSC, the A8 link and the GMP link form a one-to-one correspondence relationship for one PCF, it is not necessary to judge that the currently received A8 link establishment request is the first A8 link establishment request of the cluster group under the BSC, and the cluster group also has only this one A8 link establishment request under the BSC, and therefore, the PCF does not need to prepare for buffering the A8 link information that is established by the request, and thus, when establishing the shared GMP link, the flow adopted is the same as that in the prior art, that is: step 301, step 303, step 304 and step 305 described in fig. 3, and step 402' described in fig. 4 are not necessarily executed.

Because, the problem solved by the invention is directed to the following calls: a non-first call received by the BSC/PCF when the cluster group does not currently have an A8/GMP link established successfully; for the first call of the cluster group received by the BSC/PCF and the non-first call received by the BSC/PCF when the cluster group currently has a successfully established A8/GMP link, the establishment of the shared A8/GMP link is performed by using the prior art, which does not belong to the problem related to the present invention, and therefore, the detailed description is not provided herein.

In summary, the method of the present invention can solve the problems of repeated establishment of shared links, call loss caused by unavailable links, etc. which often occur in the prior art when establishing shared A8 and/or GMP links, and can really and effectively utilize system resources to realize shared links, ensure reasonable success rate of call establishment of trunking services, and improve service quality.

The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for establishing a shared link in a digital trunking system, the method comprising:

a. after receiving the cluster call establishment request, the radio access network RAN judges whether the current call is the first call of the current call cluster group, if so, establishes a link for the current call, and ends the current processing; otherwise, executing the step b;

2. The method of claim 1, wherein before releasing the current buffered call in step c, the method further comprises:

c3. judging whether the link establishment is successful or failed in the step c2, and if the link establishment is successful, adding the cached remaining call information to the information of the link in the step c2 which is successfully established; if it fails, return to step c1.

3. The method according to claim 1 or 2, wherein the established link is: a group mapping protocol GMP link between a packet control function entity PCF in RAN and an external key, namely a service server PS;

in the step a:

the cluster call establishment request received by the RAN is an A8 link establishment request received by the PCF;

the judgment is as follows: the PCF judges whether the current call is a first A8 link establishment request of the cluster group; alternatively, it is determined whether the current call is the first A8 link establishment request of the cluster group under the base station controller BSC of the current call.

4. The method according to claim 1 or 2, wherein the established link is: an A8 link between the RAN internal base station controller BSC and the packet control function entity PCF;

in the step a:

the cluster call establishment request is a cluster call establishment request received by the BSC;

the judgment is as follows: the BSC judges whether the current call is a first cluster call establishment request of the cluster group under the BSC.

5. The method of claim 4, wherein when establishing the A8 link, the method further comprises: the PCF establishes a group mapping protocol, GMP, link with the push-to-talk service server PS for the call currently requesting establishment of the A8 link.

6. The method of claim 4, wherein when establishing the A8 link, the method further comprises:

PCF judges whether the A8 link requested to be established currently is the A8 link requested to be established for the first time in the cluster group, if so, the PCF and the PS establish a GMP link for the call of the A8 link requested to be established currently, and ends the current processing; otherwise, executing step b 11;

7. The method of claim 6, wherein before releasing the currently buffered call in step c11, the method further comprises:

c113. judging whether the GMP link establishment in step c112 is successful or unsuccessful, and if successful, adding the cached remaining call information to the information of the GMP link in step c112 that is successfully established; if not, return to step c111.

8. The method of claim 3, wherein the determining whether the GMP link establishment is successful or failed is: PCF judges whether the current established GMP link is successful or failed according to whether the GMP link establishment confirmation message returned by PS is received within the time specified by the protocol and the reason value carried by the message indicates that the link establishment is successful; or,

9. The method of claim 4, wherein the method for determining whether the A8 link establishment is successful or failed is as follows: the BSC judges whether the currently established A8 link is successful or failed according to whether an A8 link connection response returned by the PCF is received within the time specified by the protocol; or,

10. The method of claim 6, wherein the determining whether the GMP link establishment is successful or failed is: PCF judges whether the current established GMP link is successful or failed according to whether the GMP link establishment confirmation message returned by PS is received within the time specified by the protocol and the reason value carried by the message indicates that the link establishment is successful; or,