WO2019136635A1 - Cluster communication system, cluster terminal, cluster core network and method for switching cells - Google Patents

Abstract

Disclosed by the present invention are a cluster communication system, a cluster terminal, a cluster core network and a method for switching cells. The method comprises: receiving a handover request of a cluster terminal, the handover request comprising information of a target cell; determining whether the target cell is a cell that has already established a group call or not according to the information of the target cell; if determined that the target cell is a cell that has already established a group call, sending a group call group number and a group call message transmission status of a source cell to the target cell by means of the cluster terminal; acquiring a group call message currently transmitted by the target cell, comparing the group call message transmission status of the source cell to the currently transmitted group call message, and acquiring a missing group call message; and sending the missing group call message to the cluster terminal by means of the target cell. The present invention may prevent packet loss of group call messages and improve the usage experience of a user.

Description

Cluster communication system, cluster terminal, cluster core network and method for switching cells

[Technical Field]

 The present invention relates to the field of communications technologies, and in particular, to a trunking communication system, a cluster terminal, a cluster core network, and a method for switching a cell.

 【Background technique】

Currently, Long Term Evolution (Long Term The broadband trunking communication system of Evolution, referred to as LTE technology, is a system that expands and implements cluster functions in conjunction with a dedicated cluster system on an LTE system. In the cluster system of the prior art, the group called the trunking terminal switches the cell, and belongs to the hard handover. Since there is no information transmission between the source cell and the target cell, the group call packet is lost when the group call is called the cluster terminal to switch the cell. , seriously affecting the user's experience.

 [Summary of the Invention]

The technical problem to be solved by the present invention is to provide a cluster communication system, a cluster terminal, a cluster core network, and a method for switching cells, which can reduce packet loss of group call packets.

In order to solve the above technical problem, a technical solution adopted by the present invention is to provide a method for a cluster terminal to switch a cell, which includes:

Receiving a handover request of the cluster terminal, where the handover request includes information of a target cell;

Determining, according to the information of the target cell, whether the target cell is a cell that has established a group call;

If it is determined that the target cell is a cell that has established a group call, the group terminal group number and the group call message transmission status of the source cell are sent to the target cell by using the cluster terminal;

Obtaining a group call message that is currently transmitted by the target cell, and comparing the group call message transmission status of the source cell with the currently transmitted group call message to obtain a missing group call message;

And sending, by the target cell, the missing group call message to the cluster terminal.

In order to solve the above technical problem, another technical solution adopted by the present invention is to provide a trunking communication system, which includes a cluster core network and a cluster terminal, wherein the cluster core network establishes a group call session with the cluster terminal through a cell, where :

Receiving, by the cluster core network, a handover request of the cluster terminal, where the handover request includes information of a target cell;

Determining, by the cluster core network, whether the target cell is a cell that has established a group call according to information of the target cell;

If the cluster core network determines that the target cell is a cell that has established a group call, the cluster terminal sends the group call group number and the group call message transmission status of the source cell to the target cell;

The cluster core network obtains a group call message currently transmitted by the target cell, and compares the group call message transmission status of the source cell with the currently transmitted group call message to obtain a missing group call message;

The cluster core network sends the missing group call message to the cluster terminal by using the target cell.

In order to solve the above technical problem, another technical solution adopted by the present invention is to provide a cluster core network, which includes a processor and a memory connected to the processor, the memory is used to store a program, and the processor executes The program implements the following steps:

Receiving a handover request of the cluster terminal, where the handover request includes information of a target cell;

Determining, according to the information of the target cell, whether the target cell is a cell that has established a group call;

If it is determined that the target cell is a cell that has established a group call, the group call group number of the source cell and the group call message transmission status are sent to the target cell;

Obtaining a group call message currently transmitted by the target cell, and comparing the group call message transmission status of the source cell with the currently transmitted group call message, to obtain a missing group call message;

And sending, by the target cell, the missing group call message to the cluster terminal.

In order to solve the above technical problem, another technical solution adopted by the present invention is to provide a method for a cluster terminal to switch a cell, which includes:

Generating a handover request, and sending the handover request to the cluster core network, where the handover request includes information of the target cell, so that the cluster core network determines, according to the information of the target cell, whether the target cell is an established group call. Community

When the cluster core network determines that the target cell is the cell that has established the group call, acquiring the group call group number and the group call message transmission status of the source cell, and setting the group call group number of the source cell And sending the group call message transmission status to the cluster core network;

A missing group call message is received from the target cell.

In order to solve the above technical problem, another technical solution adopted by the present invention is to provide a cluster terminal, which includes a processor and a memory connected to the processor, the memory is used to store a program, and the processor executes the The program implements the following steps:

Generating a handover request, and sending the handover request to the cluster core network, where the handover request includes information of the target cell, so that the cluster core network determines, according to the information of the target cell, whether the target cell is an established group call. Community

When the cluster core network determines that the target cell is the cell that has established the group call, acquiring the group call group number and the group call message transmission status of the source cell, and setting the group call group number of the source cell And sending the group call message transmission status to the cluster core network;

A missing group call message is received from the target cell.

The invention has the beneficial effects that, in the case of the prior art, the embodiment of the present invention receives the handover request of the cluster terminal, the handover request includes the information of the target cell, and determines whether the target cell is an established group according to the information of the target cell. If the target cell is a cell that has established a group call, the group terminal group number and the group call message transmission status of the source cell are sent to the target cell through the cluster terminal; and the group call message transmission of the source cell is compared. The group call packet of the current cell of the status and the target cell is obtained, and the missing group call message is obtained; the missing group call message is sent to the cluster terminal by the target cell; because the cluster terminal sets the group call group number and group call of the source cell The text transmission status is sent to the target cell, and the group call message transmission status of the source cell and the current group call message of the target cell are compared to obtain the missing group call message, which can prevent packet loss of the group call message and improve User experience.

 [Description of the Drawings]

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings which are required to be used in the description of the embodiments will be briefly described. It is obvious that the drawings in the following description are only some embodiments of the present invention. Other drawings may also be obtained from those of ordinary skill in the art in light of the inventive work. among them:

1 is a schematic flowchart of a method for a cluster terminal to switch a cell according to an embodiment of the present invention;

2 is a schematic structural diagram of a trunking communication system of FIG. 1;

3 is a schematic diagram of a group communication system in FIG. 1 transmitting a group call message;

4 is a schematic flowchart of a method for a cluster terminal to switch a cell according to another embodiment of the present invention;

FIG. 5 is a schematic flowchart of a method for a cluster terminal to switch a cell according to another embodiment of the present invention; FIG.

6 is a schematic structural diagram of a cluster terminal according to an embodiment of the present invention;

FIG. 7 is a schematic structural diagram of a cluster core network according to an embodiment of the present invention.

【Detailed ways】

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, but not all embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without departing from the inventive scope are the scope of the present invention.

1-2 is a schematic flowchart of a method for a cluster terminal to switch a cell according to an embodiment of the present invention; and FIG. 2 is a schematic structural diagram of the trunking communication system of FIG. The method for switching a cell by the cluster terminal disclosed in this embodiment is applied to a trunking communication system, where the cluster communication system includes a cluster core network 21 and a cluster terminal 22. The cluster core network 21 establishes a group call session with the cluster terminal 22 through the cell cell, wherein the cluster The communication system can include multiple cell cells.

As shown in FIG. 1, the method for the cluster terminal to switch cells includes the following steps:

S101: Receive a handover request of the cluster terminal, where the handover request includes information about the target cell.

When the trunking communication system initiates a group call session, each cell of the cluster communication system can establish a session synchronously, and the number and content of the group call code streams of different cell cells in the same group are the same, so each cell cell maintains a group call message. The unified coding may be used in one-to-one correspondence with the group call code stream, and the cell of each cell may buffer the group call message for a certain period of time.

When the cluster terminal 22 switches the cell cell, the cluster terminal 22 generates a handover request and transmits the handover request to the cluster core network 21.

RTP (Real-time Transport) adopted by the trunking communication system Protocol, real-time transport protocol) data packet, and RTP data packet has strict timing requirements. Therefore, when the cluster core network 21 receives the handover request of the cluster terminal 22, the cluster core network 21 determines the priority of the cluster terminal 22, and if the cluster terminal If the priority of 22 is higher than or equal to the preset priority, the process proceeds to step S102. In other embodiments, the cluster core network 21 may also determine the priority of the group terminal 22 corresponding to the group call session, and details are not described herein.

S102: Determine, according to information of the target cell, whether the target cell is a cell that has established a group call.

The cluster core network 21 determines whether the target cell cell2 is a cell in which the group call has been established according to the information of the target cell cell2, that is, whether the target cell cell2 is a cell in which the group call session has been established. If the cluster core network 21 determines that the target cell cell2 is a cell that has established a group call, that is, the cluster core network 21 and the target cell cell2 establish a group call session with the source cell cell1, the process proceeds to step S103. For example, the cluster core network 21 determines whether the target cell cell2 is a cell in which the group call has been established, based on the group call group number of the target cell cell2.

S103: Send, by the cluster terminal, the group call group number and the group call packet transmission status of the source cell to the target cell.

When the cluster core network 21 determines that the target cell cell 2 is a cell that has established a group call, that is, when the cluster core network 21 detects that the cluster terminal 22 is in a connected state, the cluster core network 21 uses the cluster terminal 22 to call the group cell of the source cell cell1. The group number and the group call message transmission status are sent to the target cell cell2.

As shown in FIG. 3, before the cluster terminal 22 switches the cell cell, the cluster core network 21 has transmitted the group call messages 1, 2, and 3 through the source cell cell1, and the group call message transmission status is marked as transmitted count3. When the cluster terminal 22 switches from the source cell cell1 to the target cell cell2, the cluster terminal 22 transmits the group call group number and the group call packet transmission status of the source cell cell1 to the target cell cell2, that is, the cluster terminal 22 sets the source cell cell1. The group call group number and the transmitted count3 are sent to the target cell cell2.

S104: Acquire a group call message currently transmitted by the target cell, and compare the group call message transmission status of the source cell with the currently transmitted group call message to obtain the missing group call message.

The cluster core network 21 obtains the group call message currently transmitted by the target cell cell2. For example, the cluster core network 21 obtains the current group call message of the target cell cell2 as count6, as shown in FIG. Specifically, the cluster core network 21 acquires the currently transmitted group call message of the target cell cell 2 from the cluster terminal 22, that is, the cluster terminal 22 acquires the currently transmitted group call message of the target cell cell2, and the currently transmitted group call message. Sent to the cluster core network 21.

The cluster core network 21 compares the group call message transmission status of the source cell cell1 with the current group call message of the target cell cell2 to obtain a missing group call message; for example, the source cell cell1 has transmitted count3, and the target The group call message currently transmitted by the cell 2 is count6, and the group call messages that are missing are the group call messages 4 and 5.

S105: Send the missing group call message to the cluster terminal by using the target cell.

The cluster core network 21 sends the missing group call message to the cluster terminal 22 through the target cell cell2, that is, the cluster core network 21 resends the group call messages 4 and 5 to the cluster terminal 22 through the target cell cell2.

In this embodiment, the lost group call message is obtained by comparing the group call message transmission status of the source cell and the group call message of the target cell cell2, and the missing group call message is sent to the cluster through the target cell cell2. The terminal 22 can prevent packet loss of the group call message and improve the user experience.

Referring to FIG. 4, FIG. 4 is a schematic flowchart diagram of a method for a cluster terminal to switch a cell according to another embodiment of the present invention. The method for the cluster terminal to switch cells in this embodiment includes the following steps:

S401: Receive a handover request of the cluster terminal, where the handover request includes information about the target cell.

S402: Determine, according to information of the target cell, whether the target cell is a cell that has established a group call.

The steps S401-S402 are the same as the steps S101-S102 of the foregoing embodiment, and details are not described herein again.

S403: The cluster terminal is switched to the target cell, and the group call group number and the group call packet transmission status of the source cell are sent to the target cell by the cluster terminal.

When the cluster core network 21 detects that the cluster terminal 22 is in the idle state reselection non-group call expansion, the cluster terminal 22 switches from the source cell cell1 to the target cell cell2. After the cluster terminal 22 switches to the target cell cell2, the cluster terminal 22 transmits the group call group number and the group call packet transmission status of the source cell cell1 to the target cell cell2.

As shown in FIG. 3, before the cluster terminal 22 switches the cell cell, the cluster core network 21 has transmitted the group call messages 1, 2, and 3 through the source cell cell1, and the group call message transmission status is marked as transmitted count3. After the cluster terminal 22 switches to the target cell cell2, the cluster terminal 22 sends the group call group number and the group call packet transmission status of the source cell cell1 to the target cell cell2, that is, the cluster terminal 22 sets the group call group number of the source cell cell1. And the transmitted count3 is sent to the target cell cell2.

S404: Obtain a group call message currently transmitted by the target cell, and compare the group call message transmission status of the source cell with the currently transmitted group call message to obtain the missing group call message.

S405: Send the missing group call message to the cluster terminal by using the target cell.

The steps S404-S405 are the same as the steps S104-S105 of the foregoing embodiment, and details are not described herein again.

After the cluster terminal 22 switches to the target cell cell2, the cluster terminal 22 transmits the group call group number and the group call packet transmission status of the source cell cell1 to the target cell cell2, and compares the group call message of the source cell cell1. The group state packet of the current transmission of the target cell and the cell 2 is obtained, and the missing group call message is obtained. The packet of the group call is sent to the cluster terminal 22 through the cell 2 of the target cell, thereby preventing packet loss of the group call packet and improving the user. The experience of using.

Referring to FIG. 5, FIG. 5 is a schematic flowchart diagram of a method for a cluster terminal to switch a cell according to another embodiment of the present invention. The method for the cluster terminal to switch cells in this embodiment includes the following steps:

S501: Receive a handover request of the cluster terminal, where the handover request includes information about the target cell.

Step S501 is the same as step S101 of the foregoing embodiment, and details are not described herein again.

S502: Determine, according to information of the target cell, whether the target cell is a cell that has established a group call;

The cluster core network 21 determines whether the target cell cell2 is a cell that has established a group call according to the information of the target cell cell2. If the cluster core network 21 determines that the target cell cell2 is a cell that does not establish a group call, the cluster terminal 22 is in an idle state reselection. If the group call is extended, the process proceeds to step S503. The cluster core network 21 establishes a group call session with the cluster terminal 22 through the source cell cell1, and the cluster core network 21 sends a group call message to the cluster terminal 22 through the source cell cell1, and the target cell cell2 is outside the group call session.

S503: Establish an RRC (Radio Resource Control) connection with the target cell.

The cluster core network 21 establishes an RRC connection with the target cell, that is, the cluster core network 21, the target cell cell2, the source cell cell1, and the cluster terminal 22 establish a group call session. Specifically, the following steps are included:

The cluster core network 21 obtains a group call extension request from the target cell cell2;

The cluster core network 21 establishes a group call with the target cell cell2 according to the group call extension request, and sends the NAS (Non-access). Stratum, non-access stratum) message to the target cell cell2, The NAS message includes the group call group number of the source cell and the group call message transmission status. After the cluster core network 21 establishes a group call with the target cell cell 2 according to the group call extension request, the process proceeds to step S504.

S504: Send a group call data back propagation request to the source cell.

The cluster core network 21 sends a group call data backhaul request to the source cell cell1.

S505: Send the missing group call message to the target cell by using the source cell.

The cluster core network 21 sends the missing group call message to the target cell cell2 through the source cell cell1, and the cluster core network 21 further sends the count value of each group call session to the source cell cell1. For example, if the cluster core network 21 has sent the group call messages 1, 2, and 3 through the source cell cell1, the missing group call packets are 4, 5, and 6, and the source cell cell 1 will have the missing group call packets 4 and 5. And 6 is sent to the target cell cell2.

S506: Send a group call message to the target cell.

After the cluster core network 21 establishes a group call with the target cell cell2, the cluster core network 21 sends a group call message to the target cell cell2. For example, the cluster core network 21 sends group call messages 1, 2, 3, 4, 5, and 6 values. Target cell cell2.

S507: Performing a repetition elimination and sorting process on the missing group call message and the group call message by using the target cell;

The cluster core network 21 performs the method of repeatedly eliminating and sorting the missing group call packets and the group call packets through the target cell cell2, that is, the group call packets missing by the cluster core network 21 through the target cell cell2 are 4, 5, and 6 and the group. The call messages 1, 2, 3, 4, 5, and 6 are subjected to repeated elimination and sorting processing to obtain missing group call messages of 4, 5, and 6.

Since the trunking communication system adopts the RTP protocol, the RTP sequence number can be up to 65535, and the RTP sequence number is greater than 65535. Since the interval of the group call message can be 20 ms, the time difference between the cells of the two cells is not large, and the cluster core network 21 repeatedly performs the elimination and sorting process on the missing group call message and the group call message through the target cell cell2. The steps can be included:

If the sequence numbers of the two group call messages are the same, one group call message in the two group call messages is deleted;

Determine whether the group call message is an out-of-window message;

If yes, it is determined whether the message outside the window is the last round of group call message;

If yes, the group call message is sent preferentially.

Among them, the pre-defined window message satisfies the following relationship:

Snmin =< rtp sn <SNmin+RTP_WINDOW_SIZE

Where SNmin is the minimum RTP sequence number received by the target cell cell2. RTP_WINDOW_SIZE is fixed at 65536/2=32768.

S508: Send the missing group call message to the cluster terminal by using the target cell.

The same as S105 of the above embodiment, and details are not described herein again.

In this embodiment, when the cluster terminal 22 is in the idle state reselection group call extension, the target cell cell2 can implement the retransmission to ensure the continuity of the service, and can prevent the group call packet from being lost, thereby improving the user experience.

The present invention also provides a trunking communication system. As shown in FIG. 2, the trunking communication system includes a cluster core network 21 and a cluster terminal 22. The cluster core network 21 establishes a group call session with the cluster terminal 22 through the cell cell, wherein the cluster communication The system can include multiple cell cells.

The cluster core network 21 receives the handover request of the cluster terminal 22, and the handover request includes information of the target cell. The cluster core network 21 determines, according to the information of the target cell, whether the target cell cell2 is a cell that has established a group call.

If the cluster core network 21 determines that the target cell is a cell that has established a group call, the cluster terminal 22 transmits the group call group number and the group call message transmission status of the source cell cell1 to the target cell cell2. The cluster core network 21 obtains the missing group call message by comparing the group call message transmission status of the source cell and the group call message of the target cell cell2, and the cluster core network 21 sends the missing group call message through the target cell cel12. The text is to the cluster terminal 22.

The cluster core network 21 in this embodiment may be the cluster core network 21 described in the foregoing embodiment, and details are not described herein again.

The present invention also provides a cluster terminal. As shown in FIG. 6, the cluster terminal 22 includes a transceiver 221, a processor 222, and a memory 223. The processor 222 is connected to the transceiver 221 and the memory 223, respectively, and the transceiver 221 and the cluster core. The network 21 is connected, the memory 223 is used to store programs, and the processor 222 executes the program to implement the following steps:

Generating a handover request, and sending a handover request to the cluster core network 21, the handover request including the information of the target cell cell2, so that the cluster core network 21 determines, according to the information of the target cell cell2, whether the target cell cell2 is a cell that has established a group call;

When the cluster core network 21 determines that the target cell is the cell that has established the group call, the group call group number and the group call packet transmission state of the source cell cell1 are obtained, and the group call group number and the group call packet of the source cell cell1 are obtained. The transmission status is sent to the cluster core network 21, so that the cluster core network 21 compares the group call message transmission status of the source cell cell1 with the current group call message of the target cell cell2 to obtain a missing group call message, for example: The source cell cell1 has transmitted the count3, and the group call message currently transmitted by the target cell cell2 is count6, and the group call messages that are missing are group call messages 4 and 5;

The missing group call message is obtained from the target cell cell2, and the cluster core network 21 sends the missing group call message to the cluster terminal 22 through the target cell cell2.

The cluster terminal 22 in this embodiment may be the cluster terminal 22 described in the foregoing embodiment, and details are not described herein again.

The cluster terminal 22 disclosed in the present invention may specifically be a mobile phone, a tablet, a computer or a wearable terminal.

The present invention also provides a cluster core network. As shown in FIG. 7, the cluster core network 21 includes a first transceiver 211, a first processor 212, and a first memory 213, and the first processor 212 and the first transceiver respectively. The first memory 211 is connected to the cluster terminal 22, the first memory 213 is used to store the program, and the first processor 212 executes the program to implement the following steps:

Receiving a handover request of the cluster terminal 22, where the handover request includes information of the target cell cell2;

Determining, according to information of the target cell cell2, whether the target cell cell2 is a cell that has established a group call;

If it is determined that the target cell cell2 is a cell that has established a group call, the group call group number of the source cell cell1 and the group call message transmission status are sent to the target cell cell2;

Obtaining the group call message currently transmitted by the target cell cell2, and comparing the group call message transmission status of the source cell and the currently transmitted group call message to obtain the missing group call message;

The missing group call message is sent to the cluster terminal 22 through the target cell cell2.

In summary, the embodiment of the present invention receives the handover request of the cluster terminal, the handover request includes the information of the target cell, and determines, according to the information of the target cell, whether the target cell is a cell that has established a group call, and if it is determined that the target cell is If the cell of the group call is established, the group call group number and the group call message transmission status of the source cell are sent to the target cell through the cluster terminal; the group call message transmission status of the source cell and the current group call of the target cell are compared. The packet is used to obtain the missing group call message; the missing cell group message is sent to the cluster terminal through the target cell; the cluster terminal sends the group call group number and the group call message transmission status of the source cell to the target cell, and compares The group call packet transmission status of the source cell and the group call packet currently transmitted by the target cell are used to obtain the missing group call packet, which can prevent packet loss of the group call packet and improve the user experience.

The above is only the embodiment of the present invention, and is not intended to limit the scope of the invention, and the equivalent structure or equivalent process transformations made by the description of the invention and the drawings are directly or indirectly applied to other related technologies. The fields are all included in the scope of patent protection of the present invention.

Claims (12)

1. A method for a cluster terminal to switch a cell, where the method includes:

   Receiving a handover request of the cluster terminal, where the handover request includes information of a target cell;

   Determining, according to the information of the target cell, whether the target cell is a cell that has established a group call;

   If it is determined that the target cell is a cell that has established a group call, the group terminal group number and the group call message transmission status of the source cell are sent to the target cell by using the cluster terminal;

   Obtaining a group call message that is currently transmitted by the target cell, and comparing the group call message transmission status of the source cell with the currently transmitted group call message to obtain a missing group call message;

   And sending, by the target cell, the missing group call message to the cluster terminal.
2. According to claim 1 The method, wherein the determining, according to the information of the target cell, whether the target cell is an established group call comprises:

   If it is determined that the target cell is a cell that has established a group call, the cluster terminal is switched to the target cell, and the group call group number and the group call message transmission status of the source cell are sent by the cluster terminal. To the target cell.
3. According to claim 1 The method, wherein the determining, according to the information of the target cell, whether the target cell is an established group call comprises:

   If it is determined that the target cell is a cell that does not establish a group call, establish an RRC connection with the target cell;

   The establishing an RRC connection with the target cell includes:

   Obtaining a group call extension request from the target cell;

   Establishing a group call with the target cell according to the group call extension request, and sending a NAS message to the target cell, the NAS The message includes a group call group number of the source cell and a group call message transmission status.
4. The method of claim 3, wherein after the establishing a group call with the target cell according to the group call extension request, the method further comprises:

   Sending a group call data back propagation request to the source cell;

   Sending, by the source cell, the missing group call message to the target cell;

   Sending a group call message to the target cell;

   Performing the elimination and sorting process on the missing group call message and the group call message by using the target cell;

   And sending, by the target cell, the missing group call message to the cluster terminal.
5. The method according to claim 4, wherein the performing the method of repeatedly eliminating and sorting the missing group call message and the group call message by the target cell comprises:

   If the sequence numbers of the two group call messages are the same, deleting one group call message in the two group call messages;

   Determining whether the group call message is an out-of-window message;

   If yes, determining whether the message outside the window is a previous round of group call message;

   If yes, the group call message is sent preferentially.
6. The method of claim 1, wherein the receiving the handover request of the cluster terminal comprises:

   Determining whether the priority of the cluster terminal is higher than or equal to a preset priority;

   If yes, it is determined whether the target cell is a cell that has established a group call.
7. A trunking communication system, wherein the trunking communication system includes a cluster core network and a cluster terminal, and the cluster core network establishes a group call session with the cluster terminal by using a cell, where:

   Receiving, by the cluster core network, a handover request of the cluster terminal, where the handover request includes information of a target cell;

   Determining, by the cluster core network, whether the target cell is a cell that has established a group call according to information of the target cell;

   If the cluster core network determines that the target cell is a cell that has established a group call, the cluster terminal sends the group call group number and the group call message transmission status of the source cell to the target cell;

   The cluster core network obtains a group call message currently transmitted by the target cell, and compares the group call message transmission status of the source cell with the currently transmitted group call message to obtain a missing group call message;

   The cluster core network sends the missing group call message to the cluster terminal by using the target cell.
8. The trunking communication system according to claim 7, wherein after the cluster terminal switches to the target cell, the cluster terminal transmits a group call group number and a group call message transmission status of the source cell to the target Community.
9. The trunking communication system according to claim 7, wherein if the cluster core network determines that the target cell is a cell that does not establish a group call, the cluster core network establishes an RRC connection with the target cell; wherein:

   The cluster core network acquires a group call extension request from the target cell;

   The cluster core network establishes a group call with the target cell according to the group call extension request, and sends a NAS message to the target cell, where the NAS message includes a group call group number and a group call message of the source cell. Transmission status

   Sending, by the cluster core network, a group call data back propagation request to the source cell;

   Sending, by the source cell, the missing group call message to the target cell;

   Sending, by the cluster core network, a group call message to the target cell;

   Deleting and sorting the missing group call message and the group call message by the cluster core network;

   The cluster core network sends the missing group call message to the cluster terminal by using the target cell.
10. A cluster core network, comprising a processor and a memory coupled to the processor, the memory for storing a program, the processor executing the program to implement the following steps:

    Receiving a handover request of the cluster terminal, where the handover request includes information of a target cell;

    Determining, according to the information of the target cell, whether the target cell is a cell that has established a group call;

    If it is determined that the target cell is a cell that has established a group call, the group call group number of the source cell and the group call message transmission status are sent to the target cell;

    Obtaining a group call message currently transmitted by the target cell, and comparing the group call message transmission status of the source cell with the currently transmitted group call message, to obtain a missing group call message;

    And sending, by the target cell, the missing group call message to the cluster terminal.
11. A method for a cluster terminal to switch a cell, where the method includes:

    Generating a handover request, and sending the handover request to the cluster core network, where the handover request includes information of the target cell, so that the cluster core network determines, according to the information of the target cell, whether the target cell is an established group call. Community

    When the cluster core network determines that the target cell is the cell that has established the group call, acquiring the group call group number and the group call message transmission status of the source cell, and setting the group call group number of the source cell And sending the group call message transmission status to the cluster core network;

    A missing group call message is received from the target cell.
12. A cluster terminal, wherein the cluster terminal includes a processor and a memory connected to the processor, the memory is used to store a program, and the processor executes the program to implement the following steps:

    Generating a handover request, and sending the handover request to the cluster core network, where the handover request includes information of the target cell, so that the cluster core network determines, according to the information of the target cell, whether the target cell is an established group call. Community

    When the cluster core network determines that the target cell is the cell that has established the group call, acquiring the group call group number and the group call message transmission status of the source cell, and setting the group call group number of the source cell And sending the group call message transmission status to the cluster core network;

    A missing group call message is received from the target cell.