Communication method and apparatus

Abstract

The present application relates to the field of communications, and discloses a communication method and apparatus. The method comprises: a first network device sends an RRC release message to a terminal device that joins a multicast session, the RRC release message being used for indicating that the terminal device is released to a non-connected state; and the first network device sends indication information to a second network device, the indication information being used for indicating whether a multicast broadcast radio bearer needs to be reconfigured for the terminal device. On the basis of the indication information, the second network device reconfigures the multicast broadcast radio bearer for the terminal device, or does not reconfigure the multicast broadcast radio bearer for the terminal device. According to the present application, by sending the indication information to the second network device, a decision basis of whether to reconfigure the multicast broadcast radio bearer for the terminal device is provided for the second network device.

Description

Communication method and device

[0001] This application claims priority to Chinese patent application number 202311292782.6, filed on September 28, 2023, with invention name “Communication Method and Device,” the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of communications, and in particular to a communication method and device. Background Art

[0003] Multicast service is a method of transmitting service data to multiple terminal devices within a group via multicast. Terminal devices can receive multicast service data in a connected state. In some user-intensive scenarios, such as concerts, stadiums, and other public safety scenarios, when the number of multicast users (i.e., the number of UEs) in a cell is too large, it may exceed the number of connected users that the cell can accommodate, causing network congestion and affecting the user service experience. To alleviate network congestion, the base station can enable terminal devices participating in a multicast session to receive multicast services in a non-connected state.

[0004] Generally speaking, the reasons why a terminal device is released to a non-connected state include: service deactivation or the network congestion mentioned above. When a terminal device accesses a new cell from an old cell, and the base station corresponding to the new cell (which can be called a new base station) is different from the base station corresponding to the old cell (which can be called an old base station), if the terminal device is released to a non-connected state due to service deactivation, the new base station may not reconfigure the multicast broadcast radio bearer; if the terminal device is released to a non-connected state to receive multicast services due to network congestion, since the multicast broadcast radio bearers of the new and old cells may be different, or because the terminal device continues to use the multicast broadcast radio bearer to receive data in a non-connected state, the wireless bearer configuration in the terminal device may change. The new cell is not sure whether the multicast broadcast radio bearer configuration on the terminal device side has changed, and cannot be sure whether the terminal device can continue to use the multicast broadcast radio bearer used in the old cell in the new cell, or cannot be sure of the multicast broadcast radio bearer configuration stored on the terminal device side. The new base station needs to reconfigure the multicast broadcast radio bearer.

[0005] Currently, a new base station cannot distinguish whether the reason why an accessed terminal device is released into a non-connected state is due to service deactivation or being released into a non-connected state to receive multicast services. This may cause the new base station to be unable to determine how to configure the multicast broadcast radio bearer. There is no feasible solution to the reconfiguration problem of the multicast broadcast radio bearer.

[0006] Summary of the Invention

[0007] The present application provides a communication method and apparatus that can provide a second network device with a decision basis for whether to reconfigure a multicast broadcast wireless bearer for a terminal device by sending indication information to the second network device.

[0008] In a first aspect, the present application provides a communication method that can be applied to a first network device. The method includes: sending a radio resource control release message to a terminal device that has joined a multicast session, the radio resource control release message being used to instruct the terminal device to release to a non-connected state; and sending indication information to a second network device, the indication information being used to indicate whether a multicast broadcast radio bearer needs to be reconfigured for the terminal device.

[0009] The method sends indication information to the second network device through the first network device, indicating whether the second network device needs to reconfigure the multicast broadcast radio bearer for the terminal device joining the multicast session. This method can enable the second network device to clearly determine whether the multicast broadcast radio bearer needs to be reconfigured for the terminal device when the terminal device accesses, and provides the second network device with a decision-making basis for reconfiguring the multicast broadcast radio bearer.

[0010] In one possible design, when the terminal device is released to a non-connected state to receive multicast services, the indication information indicates that the multicast broadcast radio bearer needs to be reconfigured for the terminal device; or, when the multicast session joined by the terminal device temporarily has no data or the multicast session is deactivated, the indication information indicates that the multicast broadcast radio bearer does not need to be reconfigured for the terminal device.

[0011] In this design, if a terminal device is released to a non-connected state to receive multicast services and then access a second network device, the second network device can reconfigure a multicast broadcast radio bearer for the terminal device. If the terminal device is released to a non-connected state because the multicast session it joined temporarily has no data or the multicast session is deactivated, and the terminal device then accesses a second network device, the second network device does not need to reconfigure a multicast broadcast radio bearer for the terminal device, reducing signaling overhead.

[0012] In one possible design, the indication information is specifically used to indicate whether the terminal device is released to a non-connected state to receive multicast services; or, the indication information is specifically used to indicate that the terminal device is released to a non-connected state to receive multicast service information; or, the indication information includes: suspension configuration information, and the suspension configuration information is used to indicate that the terminal device is released to a non-connected state to receive multicast service information.

[0013] This design indicates whether the terminal device is released to a non-connected state to receive multicast services through indication information, and can indicate to the second network device whether the terminal device needs to be reconfigured with a small signaling overhead. When the second network device reconfigures the multicast broadcast radio bearer for the terminal device, it can perform MRB reconfiguration on all multicast services received by the terminal device. By indicating that the terminal device is released to a non-connected state to receive multicast service information through indication information, it can be achieved to instruct the second network device to accurately reconfigure the multicast broadcast radio bearer for the multicast service that the terminal device is released to receive in a connected state. By suspending configuration information to indicate that the terminal device is released to a non-connected state to receive multicast service information, it can also be achieved to instruct the second network device to accurately reconfigure the multicast broadcast radio bearer for the multicast service that the terminal device is released to receive in a connected state.

[0014] In one possible design, the indication information includes a radio resource control connection release message, and the radio resource control connection release message includes suspension configuration information.

[0015] In this design, the first network device can also use the RRC release message as indication information to indicate to the second network device the multicast service information that the terminal device has been released to receive in the non-connected state through the suspension configuration information in the RRC release message. Using the RRC release message as indication information can also instruct the second network device to accurately reconfigure the multicast broadcast radio bearer for the multicast service that the terminal device has been released to receive in the connected state.

[0016] In one possible design, the method further includes: determining capability information of the second network device, the capability information including whether it supports sending multicast services to terminal devices in a non-connected state.

[0017] The sending of the indication information to the second network device includes: when the second network device supports the terminal device in the non-connected state to send the multicast service, sending the indication information to the second network device.

[0018] In this design, the first network device can send indication information only to the second network device that supports sending multicast services to terminal devices in a non-connected state, indicating whether the second network device needs to reconfigure the multicast broadcast radio bearer for the terminal device. For the second network device that does not support sending multicast services to terminal devices in a non-connected state, the indication information does not need to be sent, which can reduce signaling waste.

[0019] In one possible design, determining the capability information of the second network device includes: determining the capability information of the second network device when the Xn interface between the second network device is established or modified; or, determining the capability information of the second network device based on a terminal device context migration request message from the second network device; or, determining the capability information of the second network device based on operation, maintenance and management configuration information.

[0020] In this design, when establishing or modifying the Xn interface between the first network device and the second network device, the first network device determines the capability information of the second network device. This capability information can be obtained using control plane messages or user plane messages of the Xn interface, thus reducing signaling overhead. The first network device determines the capability information of the second network device based on a terminal device context migration request message from the second network device. This capability information can be obtained using the terminal device context migration request message, thus also reducing signaling overhead. The capability information of the second network device is synchronized to the first network device using OAM configuration information, eliminating the need for other messages and thus reducing signaling overhead.

[0021] In one possible design, the sending of indication information to the second network device includes: sending a terminal device context migration response message corresponding to the terminal device to the second network device, the terminal device context migration response message including the indication information; or, sending indication information to at least one network device within the wireless coverage range of the first network device, the at least one network device including the second network device; or, sending indication information to the second network device via a paging message.

[0022] In this design, the first network device sends indication information to the second network device through the terminal device context migration response message to indicate whether the terminal device needs to be MRB reconfigured. The indication information can be sent using existing messages, which can save signaling overhead and reduce implementation costs.

[0023] In a second aspect, the present application provides a communication device having the functionality to implement the method described in the first aspect. The functionality can be implemented in hardware or by hardware executing corresponding software. The hardware or software includes one or more units or modules corresponding to the functionality of the method described in the first aspect, for example, a sending unit.

[0024] Among them, the sending unit is used to send a wireless resource control release message to the terminal device that joins the multicast session, and the wireless resource control release message is used to instruct the terminal device to release to a non-connected state; the sending unit is also used to send indication information to the second network device, and the indication information is used to indicate whether the multicast broadcast radio bearer needs to be reconfigured for the terminal device.

[0025] In one possible design, when the terminal device is released to a non-connected state to receive multicast services, the indication information indicates that the multicast broadcast radio bearer needs to be reconfigured for the terminal device; or, when the multicast session joined by the terminal device temporarily has no data or the multicast session is deactivated, the indication information indicates that the multicast broadcast radio bearer does not need to be reconfigured for the terminal device.

[0026] In one possible design, the indication information is specifically used to indicate whether the terminal device is released to a non-connected state to receive multicast services; or, the indication information is specifically used to indicate that the terminal device is released to a non-connected state to receive multicast service information; or, the indication information includes: suspension configuration information, and the suspension configuration information is used to indicate that the terminal device is released to a non-connected state to receive multicast service information.

[0027] In one possible design, the indication information includes a radio resource control connection release message, and the radio resource control connection release message includes suspension configuration information.

[0028] In one possible design, the apparatus further includes: a processing unit, configured to determine capability information of the second network device, the capability information including whether to support sending multicast services to terminal devices in a non-connected state.

[0029] The sending unit is specifically configured to send indication information to the second network device when the second network device supports the terminal device in the non-connected state to send multicast services.

[0030] In one possible design, the processing unit is specifically used to determine the capability information of the second network device when the Xn interface between the second network device is established or modified; or, to determine the capability information of the second network device based on a terminal device context migration request message from the second network device; or, to determine the capability information of the second network device based on operation, maintenance and management configuration information.

[0031] In one possible design, the sending unit is specifically used to send a terminal device context migration response message corresponding to the terminal device to the second network device, where the terminal device context migration response message includes indication information; or, to send indication information to at least one network device within the wireless coverage range of the first network device, where the at least one network device includes the second network device; or, to send indication information to the second network device through a paging message.

[0032] In a third aspect, the present application also provides a communication device, comprising: a processor for executing computer instructions stored in a memory, so that when the computer instructions are executed, the device executes the method described in the first aspect or any possible design of the first aspect.

[0033] In a fourth aspect, the present application also provides a communication device, comprising: a processor and an interface circuit, the processor being used to communicate with other devices through the interface circuit and execute the method described in the first aspect or any possible design of the first aspect.

[0034] The communication devices described in the second to fourth aspects above can be applied to network equipment, such as the first network equipment.

[0035] In a fifth aspect, the present application also provides a computer-readable storage medium, comprising: computer software instructions; when the computer software instructions are executed in a network device or a chip built into the network device, the network device executes the method described in the first aspect or any possible design of the first aspect.

[0036] It can be understood that the beneficial effects that can be achieved by the second to fifth aspects provided above can refer to the beneficial effects in the first aspect and any possible design thereof, and will not be repeated here.

[0037] In a sixth aspect, the present application provides a communication method that can be applied to a second network device. The method includes: receiving indication information from a first network device, the indication information being used to indicate whether a multicast broadcast radio bearer needs to be reconfigured for a terminal device, where the terminal device is a terminal device that has joined a multicast session; and when the indication information indicates that a multicast broadcast radio bearer needs to be reconfigured for the terminal device, sending the reconfigured multicast broadcast radio bearer to the terminal device.

[0038] In the method, the second network device can decide whether it is necessary to reconfigure the multicast broadcast radio bearer for the terminal device that joins the multicast session according to the indication information.

[0039] In one possible design, when the terminal device is released to a non-connected state to receive multicast services, the indication information indicates that the multicast broadcast radio bearer needs to be reconfigured for the terminal device; or, when the multicast session joined by the terminal device temporarily has no data or the multicast session is deactivated, the indication information indicates that the multicast broadcast radio bearer does not need to be reconfigured for the terminal device.

[0040] In this design, if a terminal device is released to a non-connected state to receive multicast services and then access a second network device, the second network device can reconfigure a multicast broadcast radio bearer for the terminal device. If the terminal device is released to a non-connected state because the multicast session it joined temporarily has no data or the multicast session is deactivated, and the terminal device then accesses a second network device, the second network device does not need to reconfigure a multicast broadcast radio bearer for the terminal device, reducing signaling overhead.

[0041] In one possible design, the indication information is specifically used to indicate whether the terminal device is released to a non-connected state to receive multicast services; or, the indication information is specifically used to indicate that the terminal device is released to a non-connected state to receive multicast service information; or, the indication information includes: suspension configuration information, and the suspension configuration information is used to indicate that the terminal device is released to a non-connected state to receive multicast service information.

[0042] When the indication information indicates that the terminal device is released to a non-connected state to receive multicast services, sending a reconfigured multicast broadcast radio bearer to the terminal device includes: sending a reconfigured multicast broadcast radio bearer for all multicast services of the terminal device to the terminal device.

[0043] Alternatively, when the indication information indicates that the terminal device is released to a non-connected state to receive multicast service information, or the indication information includes suspension configuration information, the sending of a reconfigured multicast broadcast radio bearer to the terminal device includes: sending a multicast broadcast radio bearer to the terminal device that is reconfigured for the multicast service that the terminal device is released to a connected state to receive.

[0044] This design indicates whether the terminal device is released to a non-connected state to receive multicast services through indication information, and can indicate to the second network device whether the terminal device needs to be reconfigured with a small signaling overhead. When the second network device reconfigures the multicast broadcast radio bearer for the terminal device, it can perform MRB reconfiguration on all multicast services received by the terminal device. By indicating that the terminal device is released to a non-connected state to receive multicast service information through indication information, it can be achieved to instruct the second network device to accurately reconfigure the multicast broadcast radio bearer for the multicast service that the terminal device is released to receive in a connected state. By suspending configuration information to indicate that the terminal device is released to a non-connected state to receive multicast service information, it can also be achieved to instruct the second network device to accurately reconfigure the multicast broadcast radio bearer for the multicast service that the terminal device is released to receive in a connected state.

[0045] In one possible design, the indication information includes a radio resource control connection release message, and the radio resource control connection release message includes suspension configuration information.

[0046] In this design, the first network device can also use the RRC release message as indication information to indicate to the second network device the multicast service information that the terminal device has been released to receive in the non-connected state through the suspension configuration information in the RRC release message. Using the RRC release message as indication information can also instruct the second network device to accurately reconfigure the multicast broadcast radio bearer for the multicast service that the terminal device has been released to receive in the connected state.

[0047] In one possible design, the second network device supports sending multicast services to terminal devices in a non-connected state.

[0048] In this design, the first network device can send indication information only to the second network device that supports sending multicast services to terminal devices in a non-connected state, indicating whether the second network device needs to reconfigure the multicast broadcast radio bearer for the terminal device. For the second network device that does not support sending multicast services to terminal devices in a non-connected state, the indication information does not need to be sent, which can reduce signaling waste.

[0049] In one possible design, the method further includes: sending capability information of the second network device to the first network device when establishing or modifying an Xn interface with the first network device; or sending a terminal device context migration request message to the first network device, the terminal device context migration request message including the capability information of the second network device. Alternatively, the operation, maintenance, and management configuration information includes the capability information of the second network device.

[0050] The capability information includes whether it supports sending multicast services to terminal devices in a non-connected state.

[0051] In this design, when establishing or modifying the Xn interface between the first network device and the second network device, the first network device determines the capability information of the second network device. This capability information can be obtained using control plane messages or user plane messages of the Xn interface, thus reducing signaling overhead. The first network device determines the capability information of the second network device based on a terminal device context migration request message from the second network device. This capability information can be obtained using the terminal device context migration request message, thus also reducing signaling overhead. The capability information of the second network device is synchronized to the first network device using OAM configuration information, eliminating the need for other messages and thus reducing signaling overhead.

[0052] In one possible design, the receiving of indication information from the first network device includes: receiving a terminal device context migration response message corresponding to the terminal device sent from the first network device, the terminal device context migration response message including indication information; or, receiving a paging message sent from the first network device, the paging message including indication information.

[0053] In this design, the first network device sends indication information to the second network device through the terminal device context migration response message to indicate whether the terminal device needs to be MRB reconfigured. The indication information can be sent using existing messages, which can save signaling overhead and reduce implementation costs.

[0054] In a seventh aspect, the present application provides a communication device that can be applied to a second network device, and the device has the function of implementing the method described in the sixth aspect above. The function can be implemented by hardware or by hardware executing corresponding software. The hardware or software includes one or more units or modules corresponding to the functions of the method described in the sixth aspect above, such as a receiving unit, a sending unit, etc.

[0055] Among them, the receiving unit is used to receive indication information from the first network device, the indication information is used to indicate whether it is necessary to reconfigure the multicast broadcast radio bearer for the terminal device, and the terminal device is a terminal device joining the multicast session; the sending unit is used to send the reconfigured multicast broadcast radio bearer to the terminal device when the indication information indicates that the multicast broadcast radio bearer needs to be reconfigured for the terminal device.

[0056] In one possible design, when the terminal device is released to a non-connected state to receive multicast services, the indication information indicates that the multicast broadcast radio bearer needs to be reconfigured for the terminal device; or, when the multicast session joined by the terminal device temporarily has no data or the multicast session is deactivated, the indication information indicates that the multicast broadcast radio bearer does not need to be reconfigured for the terminal device.

[0057] In one possible design, the indication information is specifically used to indicate whether the terminal device is released to a non-connected state to receive multicast services; or, the indication information is specifically used to indicate that the terminal device is released to a non-connected state to receive multicast service information; or, the indication information includes: suspension configuration information, and the suspension configuration information is used to indicate that the terminal device is released to a non-connected state to receive multicast service information.

[0058] When the indication information indicates that the terminal device is released to a non-connected state to receive multicast services, the sending unit is specifically configured to send a multicast broadcast radio bearer that is reconfigured for all multicast services of the terminal device to the terminal device.

[0059] Alternatively, when the indication information indicates that the terminal device is released to a non-connected state to receive multicast service information, or the indication information includes suspension configuration information, the sending unit is specifically used to send a multicast broadcast radio bearer that is reconfigured for the terminal device to be released to a connected state to receive multicast service to the terminal device.

[0060] In one possible design, the indication information includes a radio resource control connection release message, and the radio resource control connection release message includes suspension configuration information.

[0061] In one possible design, the second network device supports sending multicast services to terminal devices in a non-connected state.

[0062] In one possible design, the sending unit is further configured to send capability information of the second network device to the first network device when establishing or modifying an Xn interface with the first network device; or to send a terminal device context migration request message to the first network device, the terminal device context migration request message including the capability information of the second network device. Alternatively, the operation, maintenance, and management configuration information includes the capability information of the second network device.

[0063] The capability information includes whether it supports sending multicast services to terminal devices in a non-connected state.

[0064] In one possible design, the receiving unit is specifically used to receive a terminal device context migration response message corresponding to the terminal device sent from the first network device, where the terminal device context migration response message includes indication information; or, to receive a paging message sent from the first network device, where the paging message includes indication information.

[0065] In an eighth aspect, the present application also provides a communication device, comprising: a processor for executing computer instructions stored in a memory, so that when the computer instructions are executed, the device executes the method described in the sixth aspect or any possible design of the sixth aspect.

[0066] In the ninth aspect, the present application also provides a communication device, comprising: a processor and an interface circuit, the processor being used to communicate with other devices through the interface circuit and execute the method described in the sixth aspect or any possible design of the sixth aspect.

[0067] The communication devices described in the seventh to ninth aspects above can be applied to network devices, such as the second network device.

[0068] In the tenth aspect, the present application also provides a computer-readable storage medium, including: computer software instructions; when the computer software instructions are run in a network device or a chip built into the network device, the network device executes the method described in the sixth aspect or any possible design of the sixth aspect.

[0069] It can be understood that the beneficial effects that can be achieved in the seventh to tenth aspects provided above can be referred to the beneficial effects in the sixth aspect and any possible design thereof, and will not be repeated here.

[0070] In an eleventh aspect, the present application provides a communication method that can be applied to a terminal device, such as a terminal device participating in a multicast session. The method includes: receiving a radio resource control release message from a first network device, the radio resource control release message being used to instruct the terminal device to release to a non-connected state; and sending an indication message to a second network device, the indication message being used to indicate whether a multicast broadcast radio bearer needs to be reconfigured for the terminal device.

[0071] The method sends indication information to the second network device through the terminal device, indicating whether the second network device needs to reconfigure the MRB for the terminal device joining the multicast session. This allows the second network device to clearly determine whether the MRB needs to be reconfigured for the terminal device when the terminal device accesses, providing the second network device with a decision-making basis for reconfiguring the MRB.

[0072] In one possible design, the indication information includes the resident cell information of the terminal device, and the resident cell information is used to indicate whether it is necessary to reconfigure the multicast broadcast radio bearer for the terminal device.

[0073] In this design, the terminal device's resided cell information can be used as indication information to indicate to the second network device whether the multicast broadcast radio bearer (MBRB) for the terminal device needs to be reconfigured. The terminal device's resided cell information is used to indicate to the second network device whether MBRB reconfiguration is required. The terminal device does not need to make a decision on whether to reconfigure the MRB; the terminal device only provides the second network device with a basis for making the decision.

[0074] In one possible design, the resident cell information includes information of all cells where the terminal device has resided. When at least one cell among all the cells where the terminal device has resided is not synchronized with the packet data convergence protocol, the resident cell information indicates that the terminal device needs to be reconfigured with a multicast broadcast wireless bearer; or, the resident cell information is used to indicate whether all the cells where the terminal device has resided are synchronized with the packet data convergence protocol. When at least one cell among all the cells where the terminal device has resided is not synchronized with the packet data convergence protocol, the resident cell information indicates that the terminal device needs to be reconfigured with a multicast broadcast wireless bearer; or, the resident cell information is used to indicate whether the last cell where the terminal device resided was synchronized with the packet data convergence protocol. When the last cell where the terminal device resided was not synchronized with the packet data convergence protocol, the resident cell information indicates that the terminal device needs to be reconfigured with a multicast broadcast wireless bearer.

[0075] The terminal device can only report whether it has experienced an unsynchronized cell to instruct the second network device whether to reconfigure the multicast broadcast radio bearer for the terminal device. This approach saves signaling and transfers complexity to the terminal device.

[0076] In one possible design, the sending of indication information to the second network device includes: sending a wireless resource control recovery request message to the second network device, the wireless resource control recovery request message including indication information; and / or, sending a wireless resource control recovery completion message to the second network device, the wireless resource control recovery completion message including indication information.

[0077] In this design, the indication information can be sent through a wireless resource control recovery request message and / or a wireless resource control recovery completion message. The existing wireless resource control recovery request message and / or wireless resource control recovery completion message can be used to indicate to the second network device whether it is necessary to reconfigure the multicast broadcast wireless bearer for the terminal device, which can save signaling overhead and reduce implementation costs.

[0078] In one possible design, the method further includes receiving a multicast broadcast radio bearer reconfigured for the terminal device from the second network device.

[0079] In a twelfth aspect, the present application provides a communication device having the functionality to implement the method described in the eleventh aspect. The functionality can be implemented in hardware or by hardware executing corresponding software. The hardware or software includes one or more units or modules corresponding to the functionality of the method described in the eleventh aspect, such as a receiving unit, a sending unit, etc.

[0080] Among them, the receiving unit is used to receive a wireless resource control release message from the first network device, and the wireless resource control release message is used to instruct the terminal device to release to a non-connected state, and the terminal device is a terminal device that joins the multicast session; the sending unit is used to send an indication information to the second network device, and the indication information is used to indicate whether the terminal device needs to be reconfigured with a multicast broadcast radio bearer.

[0081] In one possible design, the indication information includes the resident cell information of the terminal device, and the resident cell information is used to indicate whether it is necessary to reconfigure the multicast broadcast radio bearer for the terminal device.

[0082] In one possible design, the resident cell information includes information of all cells where the terminal device has resided. When at least one cell among all the cells where the terminal device has resided is not synchronized with the packet data convergence protocol, the resident cell information indicates that the terminal device needs to be reconfigured with a multicast broadcast wireless bearer; or, the resident cell information is used to indicate whether all the cells where the terminal device has resided are synchronized with the packet data convergence protocol. When at least one cell among all the cells where the terminal device has resided is not synchronized with the packet data convergence protocol, the resident cell information indicates that the terminal device needs to be reconfigured with a multicast broadcast wireless bearer; or, the resident cell information is used to indicate whether the last cell where the terminal device resided was synchronized with the packet data convergence protocol. When the last cell where the terminal device resided was not synchronized with the packet data convergence protocol, the resident cell information indicates that the terminal device needs to be reconfigured with a multicast broadcast wireless bearer.

[0083] In one possible design, the sending unit is specifically used to send a wireless resource control recovery request message to the second network device, the wireless resource control recovery request message includes indication information; and / or, to send a wireless resource control recovery completion message to the second network device, the wireless resource control recovery completion message includes indication information.

[0084] In one possible design, the receiving unit is further used to receive a multicast broadcast radio bearer reconfigured for the terminal device from the second network device.

[0085] In the thirteenth aspect, the present application also provides a communication device, including: a processor for executing computer instructions stored in a memory, when the computer instructions are executed, the device executes the method described in the eleventh aspect or any possible design of the eleventh aspect.

[0086] In the fourteenth aspect, the present application also provides a communication device, including: a processor and an interface circuit, the processor is used to communicate with other devices through the interface circuit, and execute the method described in the eleventh aspect or any possible design of the eleventh aspect.

[0087] The communication apparatus described in aspects 12 to 14 above can be applied to a terminal device, such as a terminal device that joins a multicast session.

[0088] In the fifteenth aspect, the present application also provides a computer-readable storage medium, including: computer software instructions; when the computer software instructions are run in a terminal device or a chip built into the terminal device, the terminal device executes the method described in the eleventh aspect or any possible design of the eleventh aspect.

[0089] It can be understood that the beneficial effects that can be achieved in the twelfth to fifteenth aspects provided above can be referred to the beneficial effects in the eleventh aspect and any possible design thereof, and will not be repeated here.

[0090] In a sixteenth aspect, the present application provides a communication method that can be applied to a second network device. The method includes: receiving indication information from a terminal device, where the terminal device is a terminal device that joins a multicast session, the indication information indicating whether a multicast broadcast radio bearer needs to be reconfigured for the terminal device; and when the indication information indicates that a multicast broadcast radio bearer needs to be reconfigured for the terminal device, sending the reconfigured multicast broadcast radio bearer to the terminal device.

[0091] The method sends indication information to the second network device through the terminal device, indicating whether the second network device needs to reconfigure the MRB for the terminal device joining the multicast session. This allows the second network device to clearly determine whether the MRB needs to be reconfigured for the terminal device when the terminal device accesses, providing the second network device with a decision-making basis for reconfiguring the MRB.

[0092] In one possible design, the indication information includes the resident cell information of the terminal device, and the resident cell information is used to indicate whether it is necessary to reconfigure the multicast broadcast radio bearer for the terminal device.

[0093] In this design, the terminal device's resided cell information can be used as indication information to indicate to the second network device whether the multicast broadcast radio bearer (MBRB) for the terminal device needs to be reconfigured. The terminal device's resided cell information is used to indicate to the second network device whether MBRB reconfiguration is required. The terminal device does not need to make a decision on whether to reconfigure the MRB; the terminal device only provides the second network device with a basis for making the decision.

[0094] In one possible design, the resident cell information includes information of all cells where the terminal device has resided. When at least one cell among all the cells where the terminal device has resided is not synchronized with the packet data convergence protocol, the resident cell information indicates that the terminal device needs to be reconfigured with a multicast broadcast wireless bearer; or, the resident cell information is used to indicate whether all the cells where the terminal device has resided are synchronized with the packet data convergence protocol. When at least one cell among all the cells where the terminal device has resided is not synchronized with the packet data convergence protocol, the resident cell information indicates that the terminal device needs to be reconfigured with a multicast broadcast wireless bearer; or, the resident cell information is used to indicate whether the last cell where the terminal device resided was synchronized with the packet data convergence protocol. When the last cell where the terminal device resided was not synchronized with the packet data convergence protocol, the resident cell information indicates that the terminal device needs to be reconfigured with a multicast broadcast wireless bearer.

[0095] The terminal device can only report whether it has experienced an unsynchronized cell to instruct the second network device whether to reconfigure the multicast broadcast radio bearer for the terminal device. This approach saves signaling and transfers complexity to the terminal device.

[0096] In one possible design, the receiving of indication information from the terminal device includes: receiving a wireless resource control recovery request message from the terminal device, the wireless resource control recovery request message including indication information; and / or receiving a wireless resource control recovery completion message from the terminal device, the wireless resource control recovery completion message including indication information.

[0097] In this design, the indication information can be sent through a wireless resource control recovery request message and / or a wireless resource control recovery completion message. The existing wireless resource control recovery request message and / or wireless resource control recovery completion message can be used to indicate to the second network device whether it is necessary to reconfigure the multicast broadcast wireless bearer for the terminal device, which can save signaling overhead and reduce implementation costs.

[0098] In a seventeenth aspect, the present application provides a communication device that can be applied to a second network device, and the device has the function of implementing the method described in the sixteenth aspect. The function can be implemented by hardware or by hardware executing corresponding software. The hardware or software includes one or more units or modules corresponding to the functions of the method described in the sixteenth aspect, such as a receiving unit, a sending unit, etc.

[0099] Among them, the receiving unit is used to receive indication information from a terminal device, where the terminal device is a terminal device joining a multicast session, and the indication information is used to indicate whether it is necessary to reconfigure the multicast broadcast radio bearer for the terminal device; the sending unit is used to send the reconfigured multicast broadcast radio bearer to the terminal device when the indication information indicates that the multicast broadcast radio bearer for the terminal device needs to be reconfigured.

[0100] In one possible design, the indication information includes the resident cell information of the terminal device, and the resident cell information is used to indicate whether it is necessary to reconfigure the multicast broadcast radio bearer for the terminal device.

[0101] In one possible design, the resident cell information includes information of all cells where the terminal device has resided. When at least one cell among all the cells where the terminal device has resided is not synchronized with the packet data convergence protocol, the resident cell information indicates that the terminal device needs to be reconfigured with a multicast broadcast wireless bearer; or, the resident cell information is used to indicate whether all the cells where the terminal device has resided are synchronized with the packet data convergence protocol. When at least one cell among all the cells where the terminal device has resided is not synchronized with the packet data convergence protocol, the resident cell information indicates that the terminal device needs to be reconfigured with a multicast broadcast wireless bearer; or, the resident cell information is used to indicate whether the last cell where the terminal device resided was synchronized with the packet data convergence protocol. When the last cell where the terminal device resided was not synchronized with the packet data convergence protocol, the resident cell information indicates that the terminal device needs to be reconfigured with a multicast broadcast wireless bearer.

[0102] In one possible design, the receiving unit is specifically used to receive a wireless resource control recovery request message from a terminal device, the wireless resource control recovery request message including indication information; and / or, receive a wireless resource control recovery completion message from the terminal device, the wireless resource control recovery completion message including indication information.

[0103] In the eighteenth aspect, the present application also provides a communication device, including: a processor for executing computer instructions stored in a memory, when the computer instructions are executed, the device executes the method described in the sixteenth aspect or any possible design of the sixteenth aspect.

[0104] In the nineteenth aspect, the present application also provides a communication device, comprising: a processor and an interface circuit, the processor being used to communicate with other devices through the interface circuit and execute the method described in the sixteenth aspect or any possible design of the sixteenth aspect.

[0105] The communication devices described in aspects 17 to 19 above can be applied to network devices, such as the second network device.

[0106] In the twentieth aspect, the present application also provides a computer-readable storage medium, comprising: computer software instructions; when the computer software instructions are executed in a network device or a chip built into the network device, the network device executes the method described in the sixteenth aspect or any possible design of the sixteenth aspect.

[0107] It can be understood that the beneficial effects that can be achieved in the seventeenth to twentieth aspects provided above can be referred to the beneficial effects in the sixteenth aspect and any possible design thereof, and will not be repeated here.

[0108] In a twenty-first aspect, the present application further provides a communication device, comprising: a transceiver unit and a processing unit. The transceiver unit can be used to send and receive information, or to communicate with other network elements. The processing unit can be used to process data. For example, the device can implement the method described in the first aspect and any possible design thereof, or the method described in the sixth aspect and any possible design thereof, or the method described in the eleventh aspect and any possible design thereof, or the method described in the sixteenth aspect and any possible design thereof, through the transceiver unit and the processing unit.

[0109] In aspect 22, the present application also provides a computer program product, which, when executed, can implement the method described in aspect 1 and any possible design thereof, or the method described in aspect 6 and any possible design thereof, or the method described in aspect 11 and any possible design thereof, or the method described in aspect 16 and any possible design thereof.

[0110] In a twenty-third aspect, the present application further provides a chip system, which is applied to a network device; the chip system includes one or more interface circuits and one or more processors; the interface circuits and the processors are interconnected by lines; the processor receives and executes computer instructions from a memory of the electronic device through the interface circuit to implement the method described in the first aspect and any possible design thereof, or the method described in the sixth aspect and any possible design thereof, or the method described in the sixteenth aspect and any possible design thereof. The network device may be a first network device or a second network device.

[0111] In the twenty-fourth aspect, the present application also provides a chip system, which is applied to a terminal device; the chip system includes one or more interface circuits and one or more processors; the interface circuit and the processor are interconnected through lines; the processor receives and executes computer instructions from the memory of the electronic device through the interface circuit to implement the method described in the eleventh aspect and any possible design thereof.

[0112] In aspect 25, the present application also provides a communication system, including: a first network device and a second network device; the first network device executes the method described in aspect 1 or any possible design of aspect 1; the second network device executes the method described in aspect 6 or any possible design of aspect 6.

[0113] In aspect 26, the present application also provides a communication system, including: a terminal device and a second network device; the terminal device executes the method described in aspect 11 or any possible design of aspect 11; the second network device executes the method described in aspect 16 or any possible design of aspect 16.

[0114] It can be understood that the beneficial effects that can be achieved in the above-mentioned aspects 21 to 26 can refer to the beneficial effects described in the first aspect, the sixth aspect, the eleventh aspect, the sixteenth aspect, etc., and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0115] FIG1 shows a schematic diagram of an MBS service transmission architecture;

[0116] FIG2 shows a schematic diagram of multicast data transmission;

[0117] FIG3 shows a schematic diagram of the composition of a communication system provided in an embodiment of the present application;

[0118] FIG4 shows a schematic diagram of the composition of a network device provided in an embodiment of the present application;

[0119] FIG5 is a schematic diagram showing a flow chart of a communication method provided in an embodiment of the present application;

[0120] FIG6 shows another flow chart of the communication method provided in an embodiment of the present application;

[0121] FIG7 shows another schematic flow chart of the communication method provided in an embodiment of the present application;

[0122] FIG8 shows another schematic flow chart of the communication method provided in an embodiment of the present application;

[0123] FIG9 shows another schematic flow chart of the communication method provided in an embodiment of the present application;

[0124] FIG10 shows another schematic flow chart of the communication method provided in an embodiment of the present application;

[0125] FIG11 shows another schematic flow chart of the communication method provided in an embodiment of the present application;

[0126] FIG12 shows another schematic flow chart of the communication method provided in an embodiment of the present application;

[0127] FIG13 shows a schematic structural diagram of a communication device provided in an embodiment of the present application;

[0128] FIG14 shows another schematic structural diagram of a communication device provided in an embodiment of the present application;

[0129] FIG15 shows another schematic structural diagram of a communication device provided in an embodiment of the present application;

[0130] FIG16 shows another schematic structural diagram of a communication device provided in an embodiment of the present application;

[0131] FIG17 shows another structural diagram of the communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0132] A multicast service is a method for transmitting service data to multiple terminal devices within a multicast group via multicast. A terminal device may also be referred to as user equipment (UE). In one example, the multicast service may be a multicast broadcast service (MBS). For example, an MBS service may be a live broadcast service, a public safety service, or a batch software update service. The MBS service may originate from a data server, meaning that the data server can provide multicast data. The UE receiving the multicast data may include at least one.

[0133] For example, FIG1 shows a schematic diagram of an MBS service transmission architecture. As shown in FIG1 , the MBS service transmission architecture may include: a UE 110 , a base station 120 , a core network device 130 , and a data server 140 .

[0134] The data server 140 may send multicast service data (also referred to as MBS data, or simply multicast data) to the core network device 130. The core network device 130 may send the received MBS data to the base station 120. The base station 120 may send the MBS data to at least one UE 110 receiving the MBS service.

[0135] When the core network device 130 sends MBS data to the base station 120 , the data may be transmitted through a common transmission channel MBS session. Each MBS session may include at least one MBS quality of service (QoS) flow.

[0136] When base station 120 sends MBS data to UE 110, it can be transmitted via an MBS radio bearer (MBS radio bearer). An MBS radio bearer can also be referred to as an MRB. An MBS radio bearer can have two transmission modes: point-to-multipoint (PTM) transmission and point-to-point (PTP) transmission.

[0137] Taking the example of sending multicast data to UE1 and UE2, Figure 2 shows a schematic diagram of multicast data transmission. As shown in Figure 2, the provider of multicast data (i.e., the content provider shown in the figure, such as the data server 140 described above) can transmit multicast data to the core network (CN). The core network can perform group management, such as maintaining UE1 and the multicast group to which UE1 belongs. The core network can manage the joining and leaving of UEs. The core network and the radio access network (RAN) can establish related multicast sessions based on protocol data unit (PDU) session-related signaling, and can also transmit information about UEs joining and leaving MBS sessions. The RAN can include base stations. For example, there are PDU sessions for UE1 and PDU sessions for UE2. In other words, multicast data transmission between the core network and the base station can rely on PDU sessions, introducing a new multicast QoS flow (MBS QoS flow).

[0138] The RAN can support both PTP and PTM transmission modes to send multicast data to UE1 or UE2, and supports dynamic switching between PTP and PTM controlled by the RAN. For example, the RAN can send data to UE1 and UE2 respectively using PTP based on the cell radio network temporary identifier (C-RNTI), or send multicast data to UE1 and UE2 using PTM based on the group radio network temporary identifier (G-RNTI).

[0139] In the 5G new radio (NR), the UE can have three radio resource control (RRC) states, namely: RRC connected state, RRC idle state, and RRC inactive state. Among them, the RRC connected state (hereinafter referred to as the connected state) can also be called the RRC active state or the RRC active state. The RRC inactive state can also be called the RRC inactive state (hereinafter referred to as the inactive state). Compared with the RRC connected state, the RRC idle state and / or the RRC inactive state can be called the RRC non-connected state (hereinafter referred to as the non-connected state).

[0140] After the UE establishes an RRC connection with a network device (such as a base station), the UE enters the RRC connected state. If the UE has no data transmission needs with the network device within a preset time period in the RRC connected state, the network device may determine that the UE has entered the RRC inactive state, and the network device may send an RRC release (RRC Release with Suspend Indication) message carrying a suspension indication to the UE. After the UE receives the RRC Release with Suspend Indication message, the UE retains its own context and enters the RRC inactive state. In the RRC inactive state, the UE can save the UE context information and only temporarily disconnect the RRC connection with the network device. When the UE has data to transmit, the UE can send an RRC resume request message to the network device, and the network device can send an RRC resume response message to the UE. After receiving the resume response message, the UE can send an RRC resume complete message to the network device, and the UE enters the RRC connected state and resumes using the UE context.

[0141] Alternatively, when the UE is in the RRC connected state, the network device may also send an RRC release message to the UE, and the UE may release the RRC connection with the network device and enter the RRC idle state. When the UE is in the RRC idle state, the UE may send an RRC establishment request message to the network device, and the network device may establish an RRC connection with the UE based on the RRC establishment request message, so that the UE may enter the RRC connected state.

[0142] It can be understood that, compared with entering the RRC connected state from the RRC idle state, the UE enters the RRC connected state faster from the RRC inactive state.

[0143] A UE in the RRC inactive state can move within the RNA and restore the RRC connection in a cell of another access network device within the RNA. The cell where the UE restores the RRC connection is generally called a new cell or a target cell.

[0144] Currently, in multicast data transmission scenarios, UEs can receive multicast data while in the RRC connected state. This means that multicast services are only available to UEs in this state, requiring the base station and core network to maintain UE information corresponding to the multicast group. Furthermore, multicast services also support core network-triggered multicast session deactivation / activation, without the UE being aware of the service status.

[0145] However, when the number of multicast users (i.e., UEs) in a cell is too large, the number of connected UEs in the cell may exceed the number of UEs that the cell can accommodate. For example, in concerts, stadiums, or other public safety scenarios with dense user density, the number of multicast users (i.e., UEs) in a cell may exceed the number of connected UEs that the cell can accommodate, causing network congestion and affecting the user experience.

[0146] To alleviate network congestion, the base station can support UEs participating in a multicast session to receive multicast services in a non-connected state (e.g., inactive state). A non-connected UE can use PTM to receive a multicast session based on a multicast configuration (or multicast PTM configuration) provided by a network device (e.g., a base station). For a multicast session, the multicast PTM configuration used for non-connected UEs to receive multicast services may include one or more of the following: a multicast session identifier (e.g., TMGI), a multicast MRB configuration, a G-RNTI for descrambling the multicast MBS traffic channel (MTCH), and multicast MTCH scheduling information.

[0147] The multicast MRB configuration may include packet data convergence protocol (PDCP) configuration, radio link control (RLC) configuration, and the like of the multicast MRB.

[0148] PCDP configuration involves configuring the PDCP entity and PDCP parameters. The PDCP entity is responsible for data compression and decompression, as well as security protection. PDCP parameters include the length of the PDCP sequence number (SN), the size of the PDCP PDU, and the PDCP retransmission timer.

[0149] RLC configuration involves configuring the RLC entity and RLC parameters. The RLC entity is responsible for data segmentation and reassembly, as well as data transmission control. RLC parameters include the RLC mode, RLC SN length, RLC PDU size, and RLC retransmission timer.

[0150] The network side can determine the configuration parameters of PDCP and RLC based on network requirements and service requirements.

[0151] The reason why the UE is released to the non-connected state may be due to service deactivation, or it may be due to network congestion as mentioned above and is released to the non-connected state to receive multicast services. When the UE accesses a new cell from an old cell, and the base station corresponding to the new cell (which may be called the new base station) is different from the base station corresponding to the old cell (which may be called the old base station), if the UE is released to the non-connected state due to service deactivation, the new base station may not reconfigure the MRB or perform MRB incremental configuration. If the UE is released to the non-connected state to receive multicast services due to network congestion, the MRBs of the new and old cells may be different, or the UE continues to use the MRB to receive data in the non-connected state, resulting in the MRB configuration in the UE may change. The new cell is not sure whether the MRB configuration on the UE side has changed, cannot be sure whether the UE can continue to use the MRB used in the old cell in the new cell, or cannot be sure of the MRB configuration stored on the UE side. The new base station needs to reconfigure the MRB.

[0152] Reconfiguring the MRB may include: sending the PDCP configuration, and / or RLC configuration, and / or MAC configuration, and / or physical layer (PHY) configuration of the MRB to the UE. Alternatively, instructing the MRB to be released and then newly created. Alternatively, instructing the PDCP entity of the MRB to be reestablished, or resetting the PDCP entity, and / or RLC entity, and / or MAC entity, and / or physical layer entity for the UE.

[0153] For example, in one implementation, MRB reconfiguration may be performed in a full configuration manner. For example, PDCP configuration, RLC configuration, MAC configuration, and PHY configuration may be sent to the UE, each of which is full configuration information.

[0154] In another implementation, MRB reconfiguration can be performed by deleting and then re-establishing the MRB, instructing the UE to delete the original MRB configuration information and sending the new PDCP configuration, RLC configuration, MAC configuration, and PHY configuration to the UE, with each configuration being full configuration information.

[0155] In another implementation, MRB reconfiguration can also be performed in accordance with PDCP reestablishment, for example, the UE can be instructed to reestablish the PDCP entity and perform PDCP configuration. In this approach, RLC configuration, MAC configuration, and PHY configuration may or may not be reconfigured, and this is not limited here.

[0156] Not reconfiguring the MRB may include: not sending the PDCP configuration, and / or RLC configuration, and / or MAC configuration, and / or physical layer (PHY) configuration of the MRB to the UE, or performing MRB incremental configuration on the UE. Alternatively, not instructing the release of the MRB and then creating a new MRB. Alternatively, not instructing the PDCP entity of the MRB to be reestablished. Alternatively, not resetting the PDCP entity, and / or RLC entity, and / or MAC entity, and / or physical layer entity for the UE.

[0157] For example, the UE may not be instructed to delete the original MRB configuration information, nor may a new PDCP configuration, RLC configuration, MAC configuration, or PHY configuration be sent to the UE. Alternatively, the UE may not be instructed to reestablish the PDCP entity. When the UE is not instructed to reestablish the PDCP entity, the RLC configuration, MAC configuration, and PHY configuration may or may not be reconfigured, without limitation herein.

[0158] However, the new base station cannot distinguish the reason why the UE is released into the non-connected state, and thus cannot decide whether to reconfigure the MRB for the UE.

[0159] For example, after a UE joins a multicast session in a cell, the UE may move and may need to reselect or switch cells. The current cell to which the UE is connected can be referred to as an old cell, or a source cell, or a previous resident cell, and the cell after the UE reselects can be referred to as a new cell, or a target cell, or a new resident cell. The base station corresponding to the old cell can be referred to as an old base station, or a source base station, and the base station corresponding to the new cell can be referred to as a new base station, or a target base station. When the UE is released to a non-connected state in the old cell, and the new base station is different from the old base station, the new base station cannot distinguish the reason for the UE being released to the non-connected state, and thus cannot decide whether the UE needs to be reconfigured with an MRB.

[0160] In addition, currently, for scenarios where the new base station does not support sending multicast services to non-connected UEs, such as when the new base station is an R17 base station, when the new base station receives access from a UE receiving multicast services in a non-connected state, it will not reconfigure the MRB (for example, it will not modify the PDCP part of the MRB configuration, as described above). Once the UE's previous cell is an unsynchronized cell, the hyperframe number (HFN) part of the UE's PDCP window variable will be reset, for example, to 0. When the new base station enters the connected state, if the PDCP window variable is not reset again, the MRB data received again will determine a count value that is inconsistent with the count value on the network side, that is, an unsynchronized COUNT value may be generated. Based on the inconsistent count value, the UE may discard data packets or incorrectly deliver data packets, causing data confusion and affecting the UE's ability to receive services. In addition, the MRB configuration information in the context obtained by the new base station based on the UE context migration process is still the one configured by the network for the UE when the old base station was used. If the new base station performs incremental configuration based on this configuration, all MRB configurations of the UE will cause problems, resulting in inconsistent understanding with the UE.

[0161] To this end, an embodiment of the present application provides a communication method that can be applied to a communication system, and the communication system may include: a first network device, a terminal device, and a second network device. The method may include: the first network device sends a radio resource control release message to a terminal device that joins a multicast session, and the radio resource control release message is used to instruct the terminal device to release to a non-connected state; the first network device sends indication information to the second network device, and the indication information is used to indicate whether the multicast broadcast radio bearer for the terminal device needs to be reconfigured. The second network device can receive the indication information from the first network device; when the indication information indicates that the multicast broadcast radio bearer for the terminal device needs to be reconfigured, the second network device can send the reconfigured multicast broadcast radio bearer to the terminal device.

[0162] This method enables a first network device to indicate to a second network device whether it is necessary to reconfigure a multicast broadcast radio bearer for a terminal device released to a non-connected state. The second network device can decide whether to reconfigure a multicast broadcast radio bearer for the terminal device released to a non-connected state based on the instruction from the first network device.

[0163] The communication method provided in the embodiments of the present application is exemplarily described below with reference to the accompanying drawings.

[0164] It should be noted that, in the description of this application, words such as "first" and "second" are only used to distinguish the description and are not used to specifically limit a certain feature. In the description of the embodiments of this application, "and / or" describes the association relationship of the associated objects, indicating that three relationships may exist. For example, A and / or B can represent three situations: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the previous and subsequent associated objects are in an "or" relationship. At least one referred to in this application refers to one or more; multiple refers to two or more. The embodiments of this application may only execute fewer steps than all the steps, or execute more steps, without limitation.

[0165] For example, Figure 3 shows a schematic diagram of the composition of a communication system provided by an embodiment of the present application. As shown in Figure 3, the communication system may include at least one terminal device 310 and at least two network devices 320.

[0166] The network device 320 may also be referred to as a radio access network device or a next-generation radio access network device, such as a base station. The terminal device 310 can communicate with the network device 320. The network device 320 provides terminal devices with functional services such as radio resource management, quality of service management, data encryption and compression, etc. Different network devices 320 can communicate with each other via the Xn interface. Different terminal devices 310 can exchange information and communicate with each other via the network device 320.

[0167] Terminal device 310 is located within the coverage of one or more cells (carriers) provided by network device 320. There may be one or more cells serving terminal device 310. When there are multiple serving cells for terminal device 310, terminal device 310 may operate in CA, dual connectivity (DC), or coordinated multi-point transmission mode.

[0168] In this communication system, a terminal device 310 can receive a multicast service in a cell corresponding to a network device 320, such as a first network device. The first network device can also release the terminal device 310 to a non-connected state to receive the multicast service, or release the terminal device 310 to a non-connected state due to service deactivation. The terminal device 310 can reselect or switch to another cell, such as a cell corresponding to a second network device. The terminal device 310 (UE) described herein is released to a non-connected state to receive the multicast service, and the non-connected state can refer to an inactive state.

[0169] In the embodiment of the present application, taking the network device 320 as a base station as an example, the first network device can be referred to as a source base station (anchor base station), an old base station, an old base station, a released base station, a base station that releases the UE connection state, a base station last served by the UE, or a base station last used by the UE, etc. The second network device can be referred to as a target base station, a new base station, a newly accessed base station, a base station newly served by the UE, or a newly used base station, etc. The present application does not limit the specific names of the network devices 320 corresponding to the terminal device before and after cell reselection.

[0170] Optionally, the communication system may be a wideband code division multiple access (WCDMA) system, a long term evolution (LTE) system, an advanced long term evolution LTE-A (LTE advanced) system, an LTE frequency division duplex (FDD) system, a universal mobile telecommunication system (UMTS), a 5G NR system, and other wireless communication systems that apply OFDM technology, etc. This application does not limit the specific type of the communication system.

[0171] For example, when the communication system is a 5G NR system, the communication system may further include a core network device, and the core network device and the network device 320 may communicate through a next generation (NG) interface.

[0172] Optionally, the terminal device 310 in the communication system may also be referred to as user equipment (UE), mobile station (MS), mobile terminal (MT), etc. The terminal device 310 can refer to a device that provides voice and / or data connectivity to a user, for example, a mobile phone ("cellular" phone), a mobile phone, a computer, a cordless phone, a Session Initiation Protocol (SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), a laptop computer, a handheld communication device, a handheld computing device, a satellite wireless device, a wireless modem card, a TV set-top box (STB), customer premises equipment (CPE), a wearable device (such as a smart watch, a smart bracelet, a pedometer, etc.), an in-vehicle device (such as a car, a bicycle, an electric car, an airplane, a ship, a train, a high-speed train, etc.), a virtual reality (VR) device, an augmented reality (AR) device, a wireless terminal in industrial control, a smart home device (such as a refrigerator, a TV, an air conditioner, an electric meter, etc.), an intelligent robot, a workshop device, a wireless terminal in a self-driving car, a remote medical device, etc. The terminal device 310 may include wireless terminals in smart grids, wireless terminals in transportation safety, wireless terminals in smart cities, or wireless terminals in smart homes, flying equipment (for example, smart robots, hot air balloons, drones, airplanes), and other devices for communicating on wireless systems, such as other MTC terminals in IoT. This application does not limit the specific form of the terminal device 310.

[0173] The network device 320 may be an access network device of the communication system, such as a base station. Optionally, in an embodiment of the present application, the network device 320 may include various forms of macro base stations, micro base stations (also known as small stations), etc. For example, the network device may include: a base station in the aforementioned WCDMA or LTE, a next generation nodeB (gNB), a next generation evolved nodeB (Ng-eNB), a transmission reception point (TRP), an evolved NodeB (eNB), a radio network controller (RNC), a nodeB (NB), a base station controller (BSC), a base transceiver station (BTS), a home base station (e.g., a home evolved NodeB, or a home NodeB, HNB), a base band unit (BBU), or a wireless fidelity (Wifi) access point (AP).

[0174] It is understood that the aforementioned communication system is merely intended to more clearly illustrate the technical solutions of the embodiments of the present application and does not constitute a limitation of the technical solutions provided by the embodiments of the present application. For example, the communication system may also include other devices, such as a network control device. The network control device may be an operation administration and maintenance (OAM) system, also known as a network management system. The network control device can manage the aforementioned network devices.

[0175] Corresponding to the communication system, the network device 320 described in the embodiment of the present application can be a base station system based on the fourth generation mobile information technology (the 4th generation mobile communication technology, 4G), or a base station system based on the fifth generation mobile information technology (the 5th generation mobile communication technology, 5G), or a base station system based on the sixth generation mobile information technology (the 6th generation mobile communication technology, 6G), and may even be applicable to base station systems or fronthaul networks in future communication networks in the future, without specific limitation.

[0176] For example, FIG4 shows a schematic diagram of the composition of a network device provided in an embodiment of the present application. The network device may be the first network device or the second network device described above. As shown in FIG4 , the network device may include: at least one processor 41, a memory 42, a communication interface 43, and a bus 44.

[0177] Processor 41 is the control center of the network device and can be a single processor or a collective term for multiple processing elements. For example, processor 41 can be a central processing unit (CPU), an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present application, such as one or more microprocessors (digital signal processors, DSPs) or one or more field programmable gate arrays (FPGAs).

[0178] The processor 41 can execute various functions of the network device by running or executing software programs stored in the memory 42 and calling data stored in the memory 42. For example, when the network device is a first network device, the steps performed by the first network device in the communication method provided in the embodiment of the present application can be executed. For another example, when the network device is a second network device, the steps performed by the second network device in the communication method provided in the embodiment of the present application can be executed.

[0179] In a specific implementation, as an embodiment, the processor 41 may include one or more CPUs, such as CPU0 and CPU1 shown in FIG. 4 .

[0180] In a specific implementation, as an embodiment, the network device may include multiple processors, such as processor 41 and processor 45 shown in Figure 4. Each of these processors may be a single-core processor (single-CPU) or a multi-core processor (multi-CPU). The processor herein may refer to one or more devices, circuits, and / or processing cores for processing data (e.g., computer program instructions).

[0181] The memory 42 can store software programs for the method steps executed by the network device and be controlled for execution by the processor 41. The memory 42 can be a read-only memory (ROM) or other type of static storage device that can store static information and instructions, a random access memory (RAM) or other type of dynamic storage device that can store information and instructions, an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, an optical disc storage (including compact discs, laser discs, optical discs, digital versatile discs, Blu-ray discs, etc.), a magnetic disk storage medium or other magnetic storage device, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited thereto.

[0182] The memory 42 may be independent and connected to the processor 41 via the bus 44. Alternatively, the memory 42 may be integrated with the processor 41, which is not limited here.

[0183] Communication interface 43 , using any transceiver or other device, is used to communicate with other devices or communication networks. Communication interface 43 may be an Ethernet interface, a radio access network (RAN) interface, a wireless local area network (WLAN) interface, or the like. Communication interface 43 may include a receiving unit for receiving functions and a transmitting unit for transmitting functions.

[0184] Bus 44 can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus. This bus can be classified as an address bus, a data bus, a control bus, etc. For ease of illustration, FIG4 shows only one thick line, but this does not imply that there is only one bus or only one type of bus.

[0185] Although a bus 44 is used in FIG. 4 , it is understandable that the bus can be replaced by other forms of connection relationships and is not limited to the bus itself.

[0186] Optionally, the structure of the terminal device described in the embodiment of the present application can also refer to the structure of the network device shown in Figure 4, which will not be repeated here.

[0187] The communication method provided in the embodiment of the present application can be applied to the communication system shown in Figure 3 above, where the first network device releases the terminal device to a non-connected state, and the terminal device reselects or switches the cell to the cell corresponding to the second network device.

[0188] It should be understood that with the evolution of network architecture and the emergence of new business scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0189] For example, taking the case where the first network device indicates to the second network device that a multicast broadcast radio bearer needs to be reconfigured for the terminal device, FIG5 shows a flow chart of the communication method provided in an embodiment of the present application. As shown in FIG5 , the communication method may include S501-S503.

[0190] S501. A first network device sends a radio resource control release message to a terminal device that has joined a multicast session. The radio resource control release message is used to instruct the terminal device to release to a non-connected state.

[0191] For example, the terminal device can access the cell corresponding to the first network device, such as cell 1, and join the multicast session to receive the multicast service. For example, the terminal device can receive the multicast service in a connected state. The specific manner in which the terminal device receives the multicast service can be referred to the above embodiments.

[0192] In some possible scenarios, the first network device can send a radio resource control release message to the terminal device, instructing the terminal device to release the connectionless state to receive multicast services, such as the network congestion scenario described above. The first network device has the ability to support sending multicast services to the terminal device in the connectionless state.

[0193] In some other possible scenarios, the first network device may also, based on the reason for service deactivation, instruct the terminal device to release to a non-connected state by sending a radio resource control release message to the terminal device. For example, when a multicast session joined by the terminal device temporarily has no data or the multicast session is deactivated, the first network device may send a radio resource control release message to the terminal device, instructing the terminal device to release to a non-connected state.

[0194] Exemplarily, the radio resource control release message (RRC release) message may instruct the terminal device to enter the inactive state to receive multicast services, or may only instruct the terminal device to enter the non-connected state. When instructing the terminal device to enter the inactive state to receive multicast services, the RRC release message may be the RRC release message (RRCRelease with suspend indication) carrying the suspend indication as described above. For example, the RRC release message may include suspend configuration (suspendConfig) information, and the suspendConfig information is used to instruct the terminal device to enter the non-connected state. When the first network device instructs the terminal device to release to the non-connected state to receive multicast services, the suspendConfig information is also used to indicate the terminal device to be released to the non-connected state to receive multicast services. The terminal device in the non-connected state can receive multicast services according to the instructions of the suspendConfig information.

[0195] As mentioned above, a terminal device in a non-connected state can use PTM to receive a multicast session according to the multicast PTM configuration provided by the network device.

[0196] In one possible design, the first network device may send a multicast PTM configuration for a terminal device in a non-connected state to receive a multicast session to the terminal device in an RRC release message. For example, the multicast PTM configuration may be included in the suspendconfig information.

[0197] In another possible design, the first network device may send an MBS control channel (MCCH) message to the UE in a manner similar to providing the MBS broadcast configuration.

[0198] For the case of sending MBS broadcast configuration to terminal devices through MCCH messages, the MCCH configuration method can be as follows: 1) The RRC release message can also include the MCCH configuration of the cell for the terminal device to obtain the MCCH message; 2) The MCCH configuration can also be sent through cell public signaling, similar to broadcasting, and the MCCH configuration is sent in the system message (such as SIBx). The terminal device obtains the multicast MCCH configuration by reading the system message, and then reads the multicast MCCH message of the cell, and then obtains the multicast PTM configuration through the MCCH message.

[0199] Optionally, if the terminal device has started receiving the multicast session in the connected state. The first network device can instruct the terminal device to use the multicast PTM configuration for receiving the multicast session in the RRC connected state to receive the multicast session in the non-connected state, or it can provide the non-connected state multicast PTM configuration through the above-mentioned RRC release message or MCCH message. The non-connected state multicast PTM configuration can be the same as the connected state configuration or different from the connected state configuration. In some other possible ways, the terminal device can also execute by default to continue to use the connected state multicast PTM configuration without the need for network-side instructions.

[0200] The above multicast PTM configuration may also be referred to as an MRB configuration, or an MRB configuration that only includes the PTM part.

[0201] After the terminal device is released to the non-connected state, it may perform cell reselection and / or switching and reselect to the cell corresponding to the second network device.

[0202] After the first network device sends the radio resource control release message to the terminal device, S502 may be executed to indicate to the second network device that a multicast broadcast radio bearer needs to be reconfigured for the terminal device.

[0203] S502: The first network device sends indication information to the second network device, where the indication information is used to indicate that a multicast broadcast radio bearer needs to be reconfigured for the terminal device.

[0204] Correspondingly, the second network device receives the indication information from the first network device.

[0205] Exemplarily, the first network device may instruct the second network device to reconfigure a multicast broadcast radio bearer (MBS radio bearer, MRB) for the terminal device by sending a message including the above instruction information to the second network device. Specific details of the MRB may refer to the description in the above embodiments.

[0206] The second network device may execute S503 to reconfigure the MRB for the terminal device according to the instruction of the instruction information. It is understandable that after the terminal device accesses the cell corresponding to the second network device, the second network device executes S503.

[0207] S503: The second network device sends the reconfigured multicast broadcast radio bearer to the terminal device.

[0208] Exemplarily, the second network device reconfiguring the MRB for the terminal device may include: configuring the MRB in a full configuration manner, or deleting and then re-establishing the MRB, or re-establishing the MRB. The manner of reconfiguring the MRB may depend on specific network requirements and service requirements and is not limited here.

[0209] Configuring the MRB using the full config method means that the second network device can provide complete configuration information to the terminal device, including parameters such as frequency and channel. For example, the MRB configuration information can include at least one of the parameters of the four layers: PDCP, RLC, MAC, and PHY. Optionally, the MRB configuration information can be carried in messages such as RRC Reconfiguration messages and RRC Recovery Complete messages.

[0210] Deleting and then establishing an MRB means first deleting the original multicast broadcast radio bearer and then re-establishing a new bearer. Optionally, deleting and then establishing an MRB can be achieved through a message, such as an RRC reconfiguration message, two RRC reconfiguration messages, or an RRC recovery complete message and a reconfiguration message, etc., which is not limited in this application.

[0211] Reestablishing an MRB refers to reconfiguring an existing multicast broadcast radio bearer, including changing at least one of the parameters of PDCP, RLC, MAC, PHY, etc. For example, the UE may be instructed to reestablish a PDCP entity and perform PDCP configuration.

[0212] The specific implementation of the above-mentioned reconfiguration of MRB can also be referred to the description in the above-mentioned embodiment.

[0213] Accordingly, the terminal device receives the reconfigured multicast broadcast radio bearer and updates the multicast broadcast radio bearer.

[0214] The embodiment shown in FIG5 above describes a situation where a first network device indicates to a second network device that a multicast broadcast radio bearer needs to be reconfigured for a terminal device. FIG6 shows another flow diagram of a communication method provided in an embodiment of the present application. As shown in FIG6, when the first network device indicates to the second network device that a multicast broadcast radio bearer does not need to be reconfigured for the terminal device, the communication method may include S601-S603.

[0215] S601. A first network device sends a radio resource control release message to a terminal device that has joined a multicast session. The radio resource control release message is used to instruct the terminal device to release to a non-connected state.

[0216] S601 can refer to the above S501 and will not be described in detail.

[0217] S602: The first network device sends indication information to the second network device, where the indication information is used to indicate that there is no need to reconfigure the multicast broadcast radio bearer for the terminal device.

[0218] Correspondingly, the second network device receives the indication information from the first network device.

[0219] Exemplarily, the first network device may send a message including the above instruction information to the second network device, thereby instructing the second network device that it does not need to reconfigure the MRB for the terminal device.

[0220] The second network device may not perform the operation of reconfiguring the MRB for the terminal device according to the instruction of the instruction information.

[0221] S603: The second network device does not reconfigure the MRB for the terminal device.

[0222] It is understandable that in actual implementation, there is no actual step in S603, and the second network device does not perform the operation of reconfiguring the MRB for the terminal device. Figure 6 is only for better explanation, represented by S603. In other words, the second network device simply does not rebuild the PDCP entity, and other underlying layers still need to be reconfigured, or can be incrementally configured. For example, the second network device may not instruct the UE to rebuild the PDCP entity, reconfigure or not reconfigure the RLC configuration, MAC configuration and PHY configuration, or perform incremental configuration on the UE, which is not limited here. The implementation logic of not reconfiguring the MRB can also refer to the description in the aforementioned embodiment.

[0223] In an embodiment of the present application, the first network device sends indication information to the second network device, indicating whether the second network device needs to reconfigure the MRB for the terminal device joining the multicast session. This allows the second network device to clearly determine whether the MRB needs to be reconfigured for the terminal device when the terminal device accesses, providing the second network device with a decision-making basis for reconfiguring the MRB.

[0224] Based on the above embodiments, the present application actually provides a communication method applied to a first network device and a communication method applied to a second network device. In the communication method applied to the first network device, the first network device can send a wireless resource control release message to the terminal device that joins the multicast session, and the wireless resource control release message is used to instruct the terminal device to release to a non-connected state; the first network device can send indication information to the second network device, and the indication information is used to indicate whether it is necessary to reconfigure the multicast broadcast radio bearer for the terminal device. In the communication method applied to the second network device, the second network device can receive indication information from the first network device; when the indication information indicates that the multicast broadcast radio bearer needs to be reconfigured for the terminal device, the second network device can send a reconfigured multicast broadcast radio bearer to the terminal device; when the indication information indicates that the multicast broadcast radio bearer does not need to be reconfigured for the terminal device, the second network device may not reconfigure the multicast broadcast radio bearer for the terminal device.

[0225] In one possible design, the indication information specifically indicates that the multicast broadcast radio bearer of the terminal device needs to be reconfigured, or that the multicast broadcast radio bearer of the terminal device does not need to be reconfigured, which can be determined by the reason why the terminal device is released to the non-connected state.

[0226] For example, when the terminal device is released to a non-connected state to receive multicast services, the indication information indicates that the multicast broadcast radio bearer needs to be reconfigured for the terminal device; or, when the multicast session joined by the terminal device temporarily has no data or the multicast session is deactivated, the indication information indicates that the multicast broadcast radio bearer does not need to be reconfigured for the terminal device.

[0227] For example, the first network device may know whether the terminal device is released into a non-connected state to receive multicast services or whether the terminal device is released into a non-connected state because the multicast session to which the terminal device joined temporarily has no data or the multicast session is deactivated. The first network device may indicate to the second network device whether it is necessary to reconfigure the multicast broadcast radio bearer for the terminal device based on the reason why the terminal device was released into the non-connected state.

[0228] In this design, if a terminal device is released to a non-connected state to receive multicast services and then access a second network device, the second network device can reconfigure a multicast broadcast radio bearer for the terminal device. If the terminal device is released to a non-connected state because the multicast session it joined temporarily has no data or the multicast session is deactivated, and the terminal device then accesses a second network device, the second network device does not need to reconfigure a multicast broadcast radio bearer for the terminal device, reducing signaling overhead.

[0229] In the case where the second network device is a network device that does not support sending multicast services to UEs in a non-connected state, such as an R17 base station, after the second network device receives access from a UE that receives multicast services in a non-connected state, the second network device can still reconfigure the MRB, such as by modifying the PDCP portion of the MRB configuration, thereby reducing the occurrence of situations such as MRB data being sent in disorder and MRB configuration problems. Optionally, the second network device and the first network device that supports sending multicast services to UEs in a non-connected state can be synchronized or asynchronous.

[0230] Optionally, in some embodiments, a terminal device may be released into a non-connected state to receive multicast services, the joined multicast session may temporarily have no data, or the multicast session may be deactivated. In such cases, the first network device may treat the terminal device as being released into a non-connected state to receive multicast services and send an indication to the second network device, instructing the second network device to reconfigure the multicast broadcast radio bearer for the terminal device.

[0231] In one possible design, the above indication information can be specifically used to indicate whether the terminal device is released to a non-connected state to receive multicast services.

[0232] Exemplarily, the indication information may indicate whether the terminal device is released to a non-connected state to receive multicast services; after receiving the indication information, the second network device may decide whether it is necessary to reconfigure the multicast broadcast radio bearer for the terminal device based on the indication result of the indication information. For example, when the indication information indicates that the terminal device is released to a non-connected state to receive multicast services, the second network device may reconfigure the multicast broadcast radio bearer for the terminal device. Alternatively, when the indication information indicates that the terminal device is released to a non-connected state and does not receive multicast services (i.e., it is released to a non-connected state, but does not receive multicast services in the non-connected state), the second network device may not reconfigure the multicast broadcast radio bearer for the terminal device.

[0233] For example, in this design, the indication information can be a 1-bit field, such as an enumeration value of "true", which can indicate whether the terminal device is released to a non-connected state to receive multicast services. This application does not limit the implementation method of the indication information (such as the type or size of the field).

[0234] This design uses indication information to indicate whether a terminal device has been released to a non-connected state to receive multicast services. This allows the second network device to be informed of the need to reconfigure a multicast broadcast radio bearer for the terminal device with minimal signaling overhead. When the second network device reconfigures a multicast broadcast radio bearer for the terminal device, it can perform MRB reconfiguration for all multicast services received by the terminal device.

[0235] When the indication information indicates that the terminal device is released to a non-connected state to receive multicast services, the step of the second network device sending a reconfigured multicast broadcast radio bearer to the terminal device may include: sending a reconfigured multicast broadcast radio bearer for all multicast services of the terminal device to the terminal device.

[0236] In another possible design, the above-mentioned indication information can be specifically used to indicate that the terminal device is released to a non-connected state to receive multicast service information.

[0237] Exemplarily, the indication information may indicate which multicast services the terminal device has received when it is released to a non-connected state, that is, the received multicast service information. After receiving the indication information, the second network device may decide whether it is necessary to reconfigure the multicast broadcast radio bearer for the terminal device based on the multicast service information received when the terminal device is released to a non-connected state. For example, when the multicast service information received by the terminal device when it is released to a non-connected state is empty, the second network device may not reconfigure the multicast broadcast radio bearer for the terminal device. When the multicast service information received by the terminal device when it is released to a non-connected state is not empty, such as including the target multicast service, the second network device may reconfigure the multicast broadcast radio bearer for the target multicast service.

[0238] Optionally, in this design, the indication information can be a temporary multicast group identifier (TMGI) list. The TMGI list can indicate which multicast services the UE is released to inactive state to receive, and can clearly indicate to the second network device which multicast services only need to be reconfigured. The second network device can reconfigure the multicast broadcast radio bearer for the multicast services that the terminal device is released to connected state to receive.

[0239] When the indication information indicates that the terminal device is released to a non-connected state to receive multicast service information, the step of the above-mentioned second network device sending a reconfigured multicast broadcast radio bearer to the terminal device may include: sending a multicast broadcast radio bearer to the terminal device that is reconfigured for the multicast service that the terminal device is released to a connected state to receive.

[0240] This design indicates the multicast service information that the terminal device is released to the non-connected state through indication information, which can instruct the second network device to accurately reconfigure the multicast broadcast radio bearer for the multicast service that the terminal device is released to the connected state to receive.

[0241] In another possible design, the above-mentioned indication information can be specifically used to indicate that the terminal device is released to the non-connected state to receive MRB information used for multicast services.

[0242] Exemplarily, the indication information may indicate which MRB information (such as an MRB identifier) ​​is used by the terminal device to receive the multicast service when it is released to a non-connected state. After receiving the indication information, the second network device may decide whether it is necessary to reconfigure the multicast broadcast radio bearer for the terminal device based on the MRB information used by the terminal device to receive the multicast service when it is released to a non-connected state. For example, when the MRB information used by the terminal device to receive the multicast service when it is released to a non-connected state is empty, the second network device may not reconfigure the multicast broadcast radio bearer for the terminal device. When the MRB information used by the terminal device to receive the multicast service when it is released to a non-connected state is not empty, such as including the target MRB, the second network device may reconfigure the multicast broadcast radio bearer for the target MRB.

[0243] This design uses indication information to indicate the MRB information used by the terminal device to be released to the non-connected state for receiving multicast services, so as to instruct the second network device to more accurately reconfigure the MRB used by the terminal device to be released to the connected state for receiving multicast services.

[0244] In another possible design, the above-mentioned indication information may include: suspension configuration information, and the suspension configuration information is used to indicate that the terminal device is released to a non-connected state to receive multicast service information.

[0245] For example, as described in the aforementioned embodiment, the RRC release message may include suspend configuration (suspendConfig) information, and the suspendConfig information is used to instruct the terminal device to enter a non-connected state. When the first network device instructs the terminal device to release to a non-connected state to receive multicast services, the suspendConfig information is also used to indicate the multicast service information that the terminal device is released to receive in the non-connected state. The terminal device in the non-connected state can receive the multicast service according to the instruction of the suspendConfig information.

[0246] When the indication information includes the suspension configuration information, the suspension configuration information may indicate to the second network device that the terminal device is released to the non-connected state to receive multicast service information. The second network device may reconfigure the multicast broadcast radio bearer for the multicast service received by the terminal device when it is released to the connected state.

[0247] When the indication information includes suspension configuration information, the step of the second network device sending a reconfigured multicast broadcast radio bearer to the terminal device may include: sending a reconfigured multicast broadcast radio bearer to the terminal device for the multicast service received by the terminal device when the terminal device is released to the connected state.

[0248] Exemplarily, the suspendConfig information may also include MRB information for the multicast service that the terminal device is released to receive in the non-connected state. When the indication information includes the suspendConfig information, and the suspendConfig information includes the MRB information for the multicast service that the terminal device is released to receive in the non-connected state, after receiving the indication information, the second network device may reconfigure the MRB for the multicast service that the terminal device is released to receive in the non-connected state based on the MRB information for the multicast service that the terminal device is released to receive in the non-connected state.

[0249] This design can indicate the terminal device to be released to a non-connected state to receive multicast service information by suspending configuration information, and / or indicate the terminal device to be released to a non-connected state to receive MRB information used for multicast services, and can also instruct the second network device to accurately reconfigure the multicast broadcast radio bearer for the multicast service that the terminal device is released to receive in a connected state.

[0250] In another possible design, the above-mentioned indication information may also include a radio resource control connection release (RRC release) message, and the RRC release message includes suspension configuration information.

[0251] In this design, the first network device can also use the RRC release message as indication information to indicate to the second network device the multicast service information that the terminal device has been released to receive in the non-connected state through the suspension configuration information in the RRC release message. Using the RRC release message as indication information can also instruct the second network device to accurately reconfigure the multicast broadcast radio bearer for the multicast service that the terminal device has been released to receive in the connected state.

[0252] In some other possible designs, the implementation of the indication information may also include any one or more of the above. In other words, the indication information may be implemented in at least one of the following implementations: indicating whether the terminal device is released to a non-connected state to receive multicast services, indicating that the terminal device is released to a non-connected state to receive multicast services, including suspension configuration information, and including a radio resource control connection release message.

[0253] For example, the indication information may include: a 1-bit indication field (refer to the above description), a TMGI list, suspendConfig information, and an RRC release message.

[0254] This application does not limit the implementation method of the indication information.

[0255] In one possible design, the first network device may also decide whether to send the above-mentioned indication information to the second network device based on the capability information of the second network device. The capability information includes whether to support the sending of multicast services to terminal devices in a non-connected state. When the second network device supports the sending of multicast services to terminal devices in a non-connected state, the first network device may send the indication information to the second network device; alternatively, when the second network device does not support the sending of multicast services to terminal devices in a non-connected state, the first network device may not send the indication information to the second network device.

[0256] For example, taking the indication information indicating that the multicast broadcast radio bearer needs to be reconfigured for the terminal device as an example, Figure 7 shows another flow chart of the communication method provided by the embodiment of the present application. As shown in Figure 7, the communication method may include S701-S704.

[0257] S701. A first network device sends a radio resource control release message to a terminal device that has joined a multicast session. The radio resource control release message is used to instruct the terminal device to release to a non-connected state.

[0258] S701 can refer to the above S501 and will not be described in detail.

[0259] S702: The first network device determines capability information of the second network device, where the capability information includes whether the second network device supports sending multicast services to terminal devices in a non-connected state.

[0260] When the second network device supports sending multicast services to terminal devices in a non-connected state, S703 is executed. When the second network device does not support sending multicast services to terminal devices in a non-connected state, subsequent steps are not executed.

[0261] S703: When the second network device supports the terminal device in the non-connected state to send a multicast service, the first network device sends indication information to the second network device, where the indication information is used to indicate that the multicast broadcast radio bearer needs to be reconfigured for the terminal device.

[0262] Correspondingly, the second network device receives the indication information from the first network device.

[0263] S704: The second network device sends the reconfigured multicast broadcast radio bearer to the terminal device.

[0264] S703-S704 can refer to the above-mentioned S502-S503 and will not be repeated here.

[0265] It can be understood that the situation where the indication information indicates that the multicast broadcast radio bearer does not need to be reconfigured for the terminal device is similar to Figure 7 and will not be repeated.

[0266] In this design, the first network device can send indication information only to the second network device that supports sending multicast services to terminal devices in a non-connected state, indicating whether the second network device needs to reconfigure the multicast broadcast radio bearer for the terminal device. For the second network device that does not support sending multicast services to terminal devices in a non-connected state, it is not necessary to send indication information, which can reduce signaling waste. In other words, in this design, the second network device can support sending multicast services to terminal devices in a non-connected state, such as the second network device can be an R18 base station.

[0267] In one possible design, the first network device may determine the capability information of the second network device when the Xn interface between the first network device and the second network device is established or modified.

[0268] Exemplarily, the Xn interface is an interface used to connect different network devices (such as gNB) in a 5G network to support transmission of the control plane and the user plane. The first network device can obtain capability information of the second network device when establishing or modifying the Xn interface between the first network device and the second network device.

[0269] For example, when the Xn interface between the second network device and the first network device is established or modified, the second network device sends the capability information of the second network device to the first network device.

[0270] In this design, when the first network device establishes or modifies the Xn interface between it and the second network device, it determines the capability information of the second network device. It can use the control plane message or user plane message of the Xn interface to obtain the capability information of the second network device, thereby reducing signaling overhead.

[0271] In another possible design, the first network device may determine the capability information of the second network device based on a terminal device context migration request message from the second network device.

[0272] Exemplarily, the second network device may send a terminal device context migration request message to the first network device, and the terminal device context migration request message may include capability information of the second network device.

[0273] Taking the UE that reselects to the cell corresponding to the second network device as the target UE as an example, the terminal device context migration request message can be the UE context migration request message of the target UE, or it can be the UE context migration request message of any other one or more UEs that performed cell switching or reselection before the target UE reselected to the cell corresponding to the second network device. For example, when the first UE switches or reselects a cell between the first network device and the second network device, the second network device can send the capability information of the second network device to the first network device through the UE context migration request message of the first UE.

[0274] Alternatively, before the target UE reselects the cell corresponding to the second network device, when other UEs switch from the cell corresponding to the second network device or reselect to the cell corresponding to the first network device, the second network device may also send the capability information of the second network device to the first network device through the UE context migration response message of the other UEs.

[0275] In this design, the first network device determines the capability information of the second network device based on the terminal device context migration request message from the second network device. The capability information of the second network device can be obtained through the terminal device context migration request message, and signaling overhead can also be reduced.

[0276] In another possible design, the first network device can determine the capability information of the second network device based on the operation, maintenance and management configuration information.

[0277] For example, the operation administration and maintenance (OAM) configuration information may include capability information of the second network device. The first network device may know whether the second network device supports sending multicast services to terminal devices in a non-connected state based on the OAM configuration information.

[0278] This design can use OAM configuration information to synchronize the capability information of the second network device to the first network device without using other messages, and can also reduce signaling overhead.

[0279] Optionally, the first network device may determine the capability information of the second network device according to one or more of the above implementation methods, or may obtain the capability information of the second network device through other messages. This application does not limit the method for determining the capability information.

[0280] In one possible design, the first network device may use a terminal device context migration response message corresponding to the terminal device to send the above-mentioned indication information to the second network device. For example, the step of the first network device sending the indication information to the second network device may include: the first network device sending a terminal device context migration response message corresponding to the terminal device to the second network device, where the terminal device context migration response message includes the indication information.

[0281] For example, Figure 8 shows another flow chart of the communication method provided in an embodiment of the present application. As shown in Figure 8 , the communication method may include S801-S806.

[0282] S801. A first network device sends an RRC release message to a terminal device that has joined a multicast session. The RRC release message is used to instruct the terminal device to release to a non-connected state.

[0283] Accordingly, the terminal device receives an RRC release message.

[0284] Exemplarily, the first network device releasing the UE to the non-connected state may include releasing the UE to the non-connected state to receive multicast services, or releasing the UE to the non-connected state due to temporary lack of data or deactivation of the multicast service session. For details, reference may be made to the aforementioned embodiments and will not be repeated here. When the UE is released to the non-connected state to receive multicast services, the UE may continue to receive the multicast services in the non-connected state.

[0285] S802. The terminal device sends an RRC recovery request message to the second network device.

[0286] Correspondingly, the second network device receives the RRC recovery request message.

[0287] Exemplarily, the terminal device may initiate access in the cell corresponding to the second network device. The terminal device triggers RRC recovery and may send an RRC recovery request (RRCResumeRequest) message to the second network device. For example, a terminal device receiving multicast services in a non-connected state may initiate access when the cell corresponding to the second network device does not have a corresponding multicast PTM configuration, or a terminal device in a non-connected state may initiate access in response to a paging message.

[0288] S803. The second network device sends a terminal device context migration request message to the first network device.

[0289] Correspondingly, the first network device receives the terminal device context migration request message.

[0290] Exemplarily, when the second network device and the first network device are different, after receiving the RRCResumeRequest message from the terminal device, the second network device may send a terminal device context migration request (RETRIEVE UE CONTEXT REQUEST) message to the first network device.

[0291] S804. The first network device sends a terminal device context migration response message to the second network device, where the terminal device context migration response message includes indication information.

[0292] Correspondingly, the second network device receives the terminal device context migration response message.

[0293] Exemplarily, the RETRIEVE UE CONTEXT RESPONSE message may include the context information of the terminal device. In this design, the terminal device context migration response message may also include the above-mentioned indication information, which may refer to the indication information described in the aforementioned embodiment and is used to indicate whether the multicast broadcast radio bearer needs to be reconfigured for the terminal device.

[0294] In some examples, for a UE receiving multicast, the RETRIEVE UE CONTEXT RESPONSE message may include a UE Context Information–Retrieve UE Context Response information element. The UE Context Information–Retrieve UE Context Response information element may include handover preparation information (HandoverPreparationInformation). The RRCRelease message or suspendconfig when releasing the UE may be introduced in the HandoverPreparationInformation as indication information to indicate to the second network device that the UE is released to the inactive state for receiving multicast services.

[0295] S805. The second network device sends an RRC recovery message to the terminal device.

[0296] Accordingly, the terminal device receives the RRC recovery message.

[0297] Exemplarily, after the terminal device completes access, the second network device may send an RRC resume (RRCResume) message to the terminal device, indicating that the terminal device has accessed. After the terminal device accesses, the second network device may execute S806 to reconfigure the MRB for the terminal device.

[0298] S806. The second network device sends the reconfigured multicast broadcast radio bearer to the terminal device.

[0299] Accordingly, the terminal device receives the reconfigured multicast broadcast radio bearer.

[0300] S806 can refer to the above-mentioned S503 and will not be described in detail. It can be understood that when the indication information indicates that MRB reconfiguration is not required, the step described in S806 is omitted.

[0301] In this design, the first network device sends indication information to the second network device through the terminal device context migration response message to indicate whether the terminal device needs to be MRB reconfigured. The indication information can be sent using existing messages, which can save signaling overhead and reduce implementation costs.

[0302] In another possible design, the first network device may also send indication information to at least one network device within the wireless coverage range of the first network device, where the at least one network device includes the second network device.

[0303] Exemplarily, the first network device may send indication information to all network devices within the wireless coverage area. When the terminal device accesses one of the network devices, the network device becomes the second network device.

[0304] This design does not limit the timing of sending the indication information. When the first network device communicates with the network device within the wireless coverage area, the indication information can be sent to the network device through the Xn interface or other means, and the sending of the indication information can be more flexible.

[0305] In another possible design, the first network device may send indication information to the second network device via a paging message. The second network device may receive a paging message sent from the first network device, where the paging message includes the indication information.

[0306] In this design, the indication information can also be sent via paging messages between network devices. For example, the indication information can be added to the paging message alongside the UE's paging identifier. Sending the indication information via paging messages can also save signaling overhead, reduce implementation costs, and enable more flexible indication information transmission.

[0307] It should be noted that in some other possible designs, the indication information can also be sent through other messages, and this application does not limit the way in which the indication information is sent.

[0308] Optionally, in some other embodiments, the first network device may send indication information to the second network device only when it is necessary to instruct the second network device to perform MRB reconfiguration on the terminal device. The indication information may only indicate that MRB reconfiguration is required for the terminal device. When MRB reconfiguration is not required for the terminal device, the first network device may not send indication information.

[0309] Optionally, in the above embodiment of the present application, the first network device may send the above indication information (refer to the above description) to the second network device in accordance with the protocol, such as: 1-bit field, TMGI list, suspendConfig information, RRC release message and other information, but for the first network device, it may not be aware of the purpose of this information, that is, the first network device may not need to determine whether this information is used to indicate whether to perform MRB reconfiguration. The second network device that receives this information can still decide whether to perform MRB reconfiguration based on this information.

[0310] The embodiments shown in Figures 5 to 8 above mainly introduce a solution in which a first network device sends an indication message to a second network device to indicate whether a multicast broadcast radio bearer needs to be reconfigured for a terminal device. The embodiment of the present application also provides a communication method, in which a terminal device can indicate to a second network device whether a multicast broadcast radio bearer needs to be reconfigured for the terminal device. In this method, a terminal device that joins a multicast session can receive a radio resource control release message from the first network device, and the radio resource control release message is used to instruct the terminal device to release to a non-connected state; the terminal device can send an indication message to the second network device, and the indication message is used to indicate whether a multicast broadcast radio bearer needs to be reconfigured for the terminal device. The second network device can receive the indication message from the terminal device; when the indication message indicates that a multicast broadcast radio bearer needs to be reconfigured for the terminal device, the second network device can send a reconfigured multicast broadcast radio bearer to the terminal device. When the indication message indicates that a multicast broadcast radio bearer does not need to be reconfigured for the terminal device, the second network device may not reconfigure the multicast broadcast radio bearer for the terminal device.

[0311] For example, taking the case where the terminal device indicates to the second network device that a multicast broadcast radio bearer needs to be reconfigured for the terminal device, Figure 9 shows another flow chart of the communication method provided in an embodiment of the present application. As shown in Figure 9, the communication method may include S901-S903.

[0312] S901. A first network device sends a radio resource control release message to a terminal device that has joined a multicast session. The radio resource control release message is used to instruct the terminal device to release to a non-connected state.

[0313] Correspondingly, the terminal device receives a radio resource control release message.

[0314] S901 can refer to the above S501 and will not be described in detail.

[0315] S902. The terminal device sends indication information to the second network device, where the indication information is used to indicate that a multicast broadcast radio bearer needs to be reconfigured for the terminal device.

[0316] Correspondingly, the second network device receives the indication information.

[0317] Exemplarily, the terminal device may instruct the second network device to reconfigure the MRB for the terminal device by sending a message including the above instruction information to the second network device.

[0318] For example, in this embodiment, the terminal device may indicate to the second network device that the multicast broadcast radio bearer needs to be reconfigured for the terminal device. The implementation of the second network device reconfiguring the MRB for the terminal device may refer to the above-mentioned embodiment.

[0319] S903: The second network device sends the reconfigured multicast broadcast radio bearer to the terminal device.

[0320] Accordingly, the terminal device receives the multicast broadcast radio bearer reconfigured for the terminal device from the second network device.

[0321] S903 may refer to the above-mentioned S503 and will not be described in detail.

[0322] The embodiment shown in FIG9 above describes a case where a terminal device indicates to a second network device that a multicast broadcast radio bearer needs to be reconfigured for the terminal device. FIG10 shows another flow diagram of a communication method provided in an embodiment of the present application. As shown in FIG10 , when the terminal device indicates to the second network device that a multicast broadcast radio bearer does not need to be reconfigured for the terminal device, the communication method may include S1001-S1003.

[0323] S1001. A first network device sends a radio resource control release message to a terminal device that has joined a multicast session. The radio resource control release message is used to instruct the terminal device to release to a non-connected state.

[0324] Correspondingly, the terminal device receives a radio resource control release message.

[0325] S1001 can refer to the above-mentioned S501 and will not be described in detail.

[0326] S1002. The terminal device sends indication information to the second network device, where the indication information is used to indicate that there is no need to reconfigure the multicast broadcast radio bearer for the terminal device.

[0327] Correspondingly, the second network device receives the indication information.

[0328] Exemplarily, the terminal device may send a message including the above-mentioned instruction information to the second network device, thereby instructing the second network device that it does not need to reconfigure the MRB for the terminal device.

[0329] The second network device may not perform the operation of reconfiguring the MRB for the terminal device according to the instruction of the instruction information.

[0330] S1003: The second network device does not reconfigure the MRB for the terminal device.

[0331] It is understandable that, in actual implementation, there is no actual step in S1003, and the second network device does not need to perform the operation of reconfiguring the MRB for the terminal device. FIG10 is only for better explanation, and is shown through S1003.

[0332] In this embodiment, the terminal device sends indication information to the second network device, indicating whether the second network device needs to reconfigure the MRB for the terminal device joining the multicast session. This allows the second network device to clearly determine whether the MRB needs to be reconfigured for the terminal device when the terminal device accesses, providing the second network device with a decision-making basis for reconfiguring the MRB.

[0333] Based on the embodiments shown in Figures 9 and 10, this embodiment actually provides a communication method applied to a terminal device and a communication method applied to a second network device, respectively. In the communication method applied to the terminal device, the terminal device can receive a radio resource control release message from the first network device, and the radio resource control release message is used to instruct the terminal device to release to a non-connected state; the terminal device can send indication information to the second network device, and the indication information is used to indicate whether the multicast broadcast radio bearer for the terminal device needs to be reconfigured. In the communication method applied to the second network device, the second network device can receive indication information from the terminal device; when the indication information indicates that the multicast broadcast radio bearer for the terminal device needs to be reconfigured, the second network device can send a reconfigured multicast broadcast radio bearer to the terminal device; when the indication information indicates that the multicast broadcast radio bearer for the terminal device does not need to be reconfigured, the second network device may not reconfigure the multicast broadcast radio bearer for the terminal device.

[0334] In one possible design, in the embodiments shown in FIG. 9 and FIG. 10 above, the indication information may include resident cell information of the terminal device, and the resident cell information is used to indicate whether the multicast broadcast radio bearer needs to be reconfigured for the terminal device.

[0335] In one implementation, the resided cell information may include information of all cells where the terminal device has resided. When at least one cell in all the cell information where the terminal device has resided is not synchronized with the packet data convergence protocol, the resided cell information indicates that the multicast broadcast radio bearer needs to be reconfigured for the terminal device.

[0336] Exemplarily, the indication information may include a list of all cells where the terminal device has resided. After receiving the indication information, the second network device may determine, based on the list of all cells where the terminal device has resided, whether there is at least one cell in all the cell information where the terminal device has resided that is not synchronized with the packet data convergence protocol (PDCP). When there is at least one cell that is not synchronized with the PDCP, it indicates that the indication information indicates that the multicast broadcast radio bearer needs to be reconfigured for the terminal device, and the second network device may reconfigure the multicast broadcast radio bearer for the terminal device. Alternatively, when all cells are PDCP synchronized, it indicates that the indication information indicates that the multicast broadcast radio bearer does not need to be reconfigured for the terminal device, and the second network device may not reconfigure the multicast broadcast radio bearer for the terminal device.

[0337] In another implementation, the resident cell information is used to indicate whether all the cells where the terminal device has resided are synchronized with the packet data convergence protocol. When there is at least one cell among all the cells where the terminal device has resided that is not synchronized with the packet data convergence protocol, the resident cell information indicates that the multicast broadcast radio bearer needs to be reconfigured for the terminal device.

[0338] Different from the previous implementation, in this implementation, the resident cell information can directly indicate whether all cells where the terminal device has resided are PDCP synchronized. For example, the resident cell information can indicate that there is at least one cell that is not PDCP synchronized, or indicate that all cells are PDCP synchronized. Similarly, when there is at least one cell that is not PDCP synchronized, the second network device can reconfigure the multicast broadcast radio bearer for the terminal device. Alternatively, when all cells are PDCP synchronized, the second network device may not reconfigure the multicast broadcast radio bearer for the terminal device.

[0339] In other words, all cells where the terminal device has resided are PDCP numbers generated based on the packet header information (MBS QFI SN) of the core network's data packet; if it has resided in a cell that is not PDCP synchronized, the terminal device's PDCP variables (such as HFN) will be reset and will not be aligned with the PDCP variables of the synchronized cell. The terminal device can only report whether it has experienced an unsynchronized cell to instruct the second network device whether to reconfigure the multicast broadcast radio bearer for the terminal device. This method saves signaling and transfers the complexity to the terminal device.

[0340] In another implementation, the resident cell information is used to indicate whether the last cell where the terminal device resided was synchronized with the Packet Data Convergence Protocol. When the last cell where the terminal device resided was not synchronized with the Packet Data Convergence Protocol, the resident cell information indicates that the multicast broadcast radio bearer needs to be reconfigured for the terminal device.

[0341] In this implementation, the terminal device may report to the second network device via indication information whether the last cell in which the terminal device resided was PDCP synchronized. The second network device may then decide whether to perform MRB reconfiguration based on whether the last cell in which the terminal device resided was PDCP synchronized. For example, when the last cell in which the terminal device resided was not PDCP synchronized, the second network device may perform MRB reconfiguration; or, when the last cell in which the terminal device resided was PDCP synchronized, the second network device may not perform MRB reconfiguration.

[0342] In this design, the resident cell information of the terminal device can be used to indicate to the second network device whether the multicast broadcast radio bearer needs to be reconfigured. The terminal device does not need to make a decision on whether to reconfigure the MRB. The terminal device only provides the decision basis to the second network device.

[0343] In another possible design, in the embodiments shown in FIG. 9 and FIG. 10 , the indication information may only indicate whether MRB reconfiguration is required.

[0344] For example, the terminal device can determine, based on the resident cell information, whether the second network device needs to reconfigure the multicast broadcast radio bearer for the terminal device. The decision-making method can refer to the decision-making method of the second network device described above and will not be described in detail. The terminal device can indicate to the second network device whether the multicast broadcast radio bearer needs to be reconfigured for the terminal device through indication information.

[0345] In this design, the logic for deciding whether the second network device needs to reconfigure the multicast broadcast radio bearer for the terminal device can be implemented on the terminal device side, and the second network device can execute the result based on the indication information reported by the terminal device, such as: reconfigure MRB or not reconfigure MRB.

[0346] Optionally, in this design, when the indication information includes the resident cell information of the terminal device described in any of the above implementations, reconfiguring the MRB may refer to: the second network device instructing the UE to reconfigure the PDCP or to reconfigure part or all of the PDCP. For example, referring to the implementation of reestablishing the MRB described in the aforementioned embodiment, the UE may be instructed to reestablish the PDCP entity and perform PDCP configuration, while the RLC configuration, MAC configuration, and PHY configuration may or may not be reconfigured.

[0347] In some other possible designs, the indication information sent by the terminal device to the second network device can also be implemented with reference to the indication information sent by the first network device to the second network device in the aforementioned embodiment. For example, the indication information sent by the terminal device to the second network device may include one or more of the following: indication information indicating whether the terminal device is released to a non-connected state to receive multicast services, indication information indicating that the terminal device is released to a non-connected state to receive multicast services, indication information including suspension configuration information, indication information including a radio resource control connection release message, indication information indicating that the terminal device is released to a non-connected state to receive MRB information used for multicast services, etc.

[0348] Exemplarily, in this design, the indication information may be a 1-bit indication field (refer to the above description), a TMGI list, suspendConfig information, an RRC release message, and the like.

[0349] Optionally, in an embodiment of the present application, the terminal device may send the above-mentioned resident cell information (refer to the above description), TMGI list, suspendConfig information, RRC release message and other information to the second network device in accordance with the protocol, but the terminal device does not perceive the purpose of this information, that is, the terminal device does not need to determine whether this information is used to indicate whether to perform MRB reconfiguration. The second network device that receives this information can still decide whether to perform MRB reconfiguration based on this information.

[0350] In one possible design, in the embodiments shown in Figures 9 and 10 above, the indication information may be sent via a radio resource control recovery request message and / or a radio resource control recovery complete message. The step of the terminal device sending the indication information to the second network device may include: sending a radio resource control recovery request message to the second network device, the radio resource control recovery request message including the indication information; and / or sending a radio resource control recovery complete message to the second network device, the radio resource control recovery complete message including the indication information.

[0351] Accordingly, the second network device may receive a radio resource control recovery request message from the terminal device; and / or receive a radio resource control recovery completion message from the terminal device, where the radio resource control recovery completion message includes indication information.

[0352] For example, Figure 11 shows another flow chart of the communication method provided in an embodiment of the present application. As shown in Figure 11, the communication method may include S1101-S1107.

[0353] S1101. The first network device sends an RRC release message to a terminal device that joins a multicast session. The RRC release message is used to instruct the terminal device to release to a non-connected state.

[0354] Accordingly, the terminal device receives an RRC release message.

[0355] S1101 can refer to the above-mentioned S801 and will not be described in detail.

[0356] S1102. The terminal device sends an RRC recovery request message to the second network device, where the RRC recovery request message includes indication information.

[0357] Correspondingly, the second network device receives the RRC recovery request message.

[0358] S1102 may refer to the above S802, the difference being that the RRC recovery request message includes indication information, and the indication information may indicate whether MRB reconfiguration is required.

[0359] S1103. The second network device sends a terminal device context migration request message to the first network device.

[0360] Correspondingly, the first network device receives the terminal device context migration request message.

[0361] S1103 can refer to the above-mentioned S803 and will not be described in detail.

[0362] S1104. The first network device sends a terminal device context migration response message to the second network device.

[0363] Correspondingly, the second network device receives the terminal device context migration response message.

[0364] S1105. The second network device sends an RRC recovery message to the terminal device.

[0365] Accordingly, the terminal device receives the RRC recovery message.

[0366] S1106. The terminal device sends an RRC recovery completion message to the second network device.

[0367] Correspondingly, the second network device receives an RRC recovery complete (RRCResumeComplete) message.

[0368] Exemplarily, after the terminal device accesses, the second network device may execute S1107 to reconfigure the MRB for the terminal device.

[0369] S1107. The second network device sends the reconfigured multicast broadcast radio bearer to the terminal device.

[0370] Accordingly, the terminal device receives the reconfigured multicast broadcast radio bearer.

[0371] S1107 can refer to the above-mentioned S503 and will not be described in detail. It can be understood that when the indication information indicates that MRB reconfiguration is not required, the step described in S1107 is omitted.

[0372] For another example, Figure 12 shows another flow chart of the communication method provided in an embodiment of the present application. As shown in Figure 12, the communication method may include S1201-S1207.

[0373] S1201. The first network device sends an RRC release message to the terminal device that joins the multicast session. The RRC release message is used to instruct the terminal device to release to a non-connected state.

[0374] Accordingly, the terminal device receives an RRC release message.

[0375] S1201 can refer to the above-mentioned S801 and will not be described in detail.

[0376] S1202. The terminal device sends an RRC recovery request message to the second network device.

[0377] Correspondingly, the second network device receives the RRC recovery request message.

[0378] S1202 may refer to the above-mentioned S802.

[0379] S1203. The second network device sends a terminal device context migration request message to the first network device.

[0380] Correspondingly, the first network device receives the terminal device context migration request message.

[0381] S1203 can refer to the above-mentioned S803 and will not be described in detail.

[0382] S1204. The first network device sends a terminal device context migration response message to the second network device.

[0383] Correspondingly, the second network device receives the terminal device context migration response message.

[0384] S1205. The second network device sends an RRC recovery message to the terminal device.

[0385] Accordingly, the terminal device receives the RRC recovery message.

[0386] S1206. The terminal device sends an RRC recovery completion message to the second network device, where the RRC recovery completion request message includes indication information.

[0387] Correspondingly, the second network device receives an RRC recovery complete (RRCResumeComplete) message. The indication information included in the RRC recovery complete message may indicate whether MRB reconfiguration is required.

[0388] Exemplarily, after the terminal device accesses, the second network device may execute S1207 to reconfigure the MRB for the terminal device.

[0389] S1207. The second network device sends the reconfigured multicast broadcast radio bearer to the terminal device.

[0390] Accordingly, the terminal device receives the reconfigured multicast broadcast radio bearer.

[0391] S1207 can refer to the above S503 and will not be described in detail. It can be understood that when the indication information indicates that MRB reconfiguration is not required, the step described in S1207 is omitted.

[0392] In some other examples, the above-mentioned RRC recovery message and RRC recovery complete message may both include indication information, which is not limited here.

[0393] In this design, the indication information can be sent through a wireless resource control recovery request message and / or a wireless resource control recovery completion message. The existing wireless resource control recovery request message and / or wireless resource control recovery completion message can be used to indicate to the second network device whether it is necessary to reconfigure the multicast broadcast wireless bearer for the terminal device, which can save signaling overhead and reduce implementation costs.

[0394] Optionally, the RRC recovery message may be referred to as msg3, and the RRC recovery complete message may be referred to as msg5. The message space of msg5 is larger, and when the indication information is sent in msg5, the message space can be better utilized.

[0395] The above embodiments respectively introduce two situations: the first network device instructs the second network device whether to reconfigure the multicast broadcast radio bearer for the terminal device, and the terminal device instructs the second network device whether to reconfigure the multicast broadcast radio bearer for the terminal device. In some other embodiments of the present application, it is also possible not to send the indication information to the second network device, and the second network device is required to reconfigure the MRB for the UE after the UE access is completed.

[0396] Illustratively, an embodiment of the present application further provides a communication method that can be applied to a second network device. In this method, the second network device can, after receiving a radio resource control recovery complete message sent by a terminal device, optionally perform an operation of reconfiguring an MRB for the terminal device, such as sending a reconfigured multicast broadcast radio bearer to the terminal device.

[0397] Optionally, in one possible design, the second network device may further obtain capability information of the terminal device, where the capability information of the terminal device includes whether the terminal device supports receiving multicast services in a non-connected state. The terminal device may optionally perform an operation of reconfiguring the MRB for the terminal device only for terminal devices that support receiving multicast services in a non-connected state. For example, when the terminal device supports receiving multicast services in a non-connected state, the second network device reconfigures the multicast broadcast radio bearer for the terminal device.

[0398] In this embodiment, the second network device may support sending multicast services to non-connected UEs, or may not support sending multicast services to non-connected UEs, and this application does not impose any restrictions on this.

[0399] It can be understood that for any of the above embodiments, the second network device can clearly determine whether it is necessary to reconfigure the MRB for the UE, which can reduce MRB configuration anomalies on the UE side and reduce the occurrence of situations where MBS multicast data cannot be received normally.

[0400] The above mainly introduces the solution provided by the embodiment of the present application from the perspective of interaction between various network elements. It is understandable that each network element, such as the first network device, the second network device, the terminal device, etc., in order to implement the above functions, includes a hardware structure and / or software module corresponding to each function.

[0401] For example, for the above scenario of the first network device sending instruction information to the second network device, the embodiment of the present application may also provide a communication device applicable to the above first network device. FIG13 shows a schematic diagram of the structure of the communication device provided by the embodiment of the present application.

[0402] As shown in FIG13 , the communication device may include: a sending unit 1301 .

[0403] Among them, the sending unit 1301 is used to send a wireless resource control release message to the terminal device that joins the multicast session, and the wireless resource control release message is used to instruct the terminal device to release to a non-connected state; the sending unit 1301 is also used to send an indication information to the second network device, and the indication information is used to indicate whether the multicast broadcast radio bearer needs to be reconfigured for the terminal device.

[0404] In one possible design, when the terminal device is released to a non-connected state to receive multicast services, the indication information indicates that the multicast broadcast radio bearer needs to be reconfigured for the terminal device; or, when the multicast session joined by the terminal device temporarily has no data or the multicast session is deactivated, the indication information indicates that the multicast broadcast radio bearer does not need to be reconfigured for the terminal device.

[0405] In one possible design, the indication information is specifically used to indicate whether the terminal device is released to a non-connected state to receive multicast services; or, the indication information is specifically used to indicate that the terminal device is released to a non-connected state to receive multicast service information; or, the indication information includes: suspension configuration information, and the suspension configuration information is used to indicate that the terminal device is released to a non-connected state to receive multicast service information.

[0406] In one possible design, the indication information includes a radio resource control connection release message, and the radio resource control connection release message includes suspension configuration information.

[0407] In one possible design, the apparatus further includes: a processing unit 1302, configured to determine capability information of the second network device, the capability information including whether to support sending multicast services to terminal devices in a non-connected state.

[0408] The sending unit 1301 is specifically configured to send indication information to the second network device when the second network device supports the terminal device in the non-connected state to send a multicast service.

[0409] In one possible design, the processing unit 1302 is specifically used to determine the capability information of the second network device when the Xn interface between the second network device is established or modified; or, to determine the capability information of the second network device based on a terminal device context migration request message from the second network device; or, to determine the capability information of the second network device based on operation, maintenance and management configuration information.

[0410] In one possible design, the sending unit 1301 is specifically used to send a terminal device context migration response message corresponding to the terminal device to the second network device, where the terminal device context migration response message includes indication information; or, to send indication information to at least one network device within the wireless coverage range of the first network device, where the at least one network device includes the second network device; or, to send indication information to the second network device through a paging message.

[0411] Optionally, the communication device shown in FIG. 13 may further include a receiving unit (not shown in the figure) for implementing a receiving function, such as receiving information from a second network device or a terminal device.

[0412] For another example, regarding the above scenario of the first network device sending instruction information to the second network device, the present invention can also provide a communication device applicable to the second network device.

[0413] As shown in FIG14 , the communication device may include: a receiving unit 1401 and a sending unit 1402 .

[0414] Among them, the receiving unit 1401 is used to receive indication information from the first network device, and the indication information is used to indicate whether it is necessary to reconfigure the multicast broadcast radio bearer for the terminal device, and the terminal device is a terminal device joining the multicast session; the sending unit 1402 is used to send the reconfigured multicast broadcast radio bearer to the terminal device when the indication information indicates that the multicast broadcast radio bearer needs to be reconfigured for the terminal device.

[0415] In one possible design, when the terminal device is released to a non-connected state to receive multicast services, the indication information indicates that the multicast broadcast radio bearer needs to be reconfigured for the terminal device; or, when the multicast session joined by the terminal device temporarily has no data or the multicast session is deactivated, the indication information indicates that the multicast broadcast radio bearer does not need to be reconfigured for the terminal device.

[0416] In one possible design, the indication information is specifically used to indicate whether the terminal device is released to a non-connected state to receive multicast services; or, the indication information is specifically used to indicate that the terminal device is released to a non-connected state to receive multicast service information; or, the indication information includes: suspension configuration information, and the suspension configuration information is used to indicate that the terminal device is released to a non-connected state to receive multicast service information.

[0417] When the indication information indicates that the terminal device is released to a non-connected state to receive multicast services, the sending unit 1402 is specifically configured to send a multicast broadcast radio bearer reconfigured for all multicast services of the terminal device to the terminal device.

[0418] Alternatively, when the indication information indicates that the terminal device is released to a non-connected state to receive multicast service information, or the indication information includes suspension configuration information, the sending unit 1402 is specifically used to send a multicast broadcast radio bearer that is reconfigured for the terminal device to be released to a connected state to receive multicast service to the terminal device.

[0419] In one possible design, the indication information includes a radio resource control connection release message, and the radio resource control connection release message includes suspension configuration information.

[0420] In one possible design, the second network device supports sending multicast services to terminal devices in a non-connected state.

[0421] In one possible design, the sending unit 1402 is further configured to send capability information of the second network device to the first network device when establishing or modifying an Xn interface with the first network device; or to send a terminal device context migration request message to the first network device, the terminal device context migration request message including the capability information of the second network device. Alternatively, the operation, maintenance and management configuration information includes the capability information of the second network device.

[0422] The capability information includes whether it supports sending multicast services to terminal devices in a non-connected state.

[0423] In one possible design, the receiving unit 1401 is specifically used to receive a terminal device context migration response message corresponding to the terminal device sent from the first network device, where the terminal device context migration response message includes indication information; or, to receive a paging message sent from the first network device, where the paging message includes indication information.

[0424] For another example: for the above scenario of the terminal device sending instruction information to the second network device, the embodiment of the present application can also provide a communication device that can be applied to the above terminal device. Figure 15 shows another structural diagram of the communication device provided by the embodiment of the present application.

[0425] As shown in FIG15 , the communication device may include: a receiving unit 1501 and a sending unit 1502 .

[0426] Among them, the receiving unit 1501 is used to receive a wireless resource control release message from the first network device, and the wireless resource control release message is used to instruct the terminal device to be released to a non-connected state, and the terminal device is a terminal device that joins the multicast session; the sending unit 1502 is used to send an indication information to the second network device, and the indication information is used to indicate whether the multicast broadcast radio bearer needs to be reconfigured for the terminal device.

[0427] In one possible design, the indication information includes the resident cell information of the terminal device, and the resident cell information is used to indicate whether it is necessary to reconfigure the multicast broadcast radio bearer for the terminal device.

[0428] In one possible design, the resident cell information includes information of all cells where the terminal device has resided. When at least one cell among all the cells where the terminal device has resided is not synchronized with the packet data convergence protocol, the resident cell information indicates that the terminal device needs to be reconfigured with a multicast broadcast wireless bearer; or, the resident cell information is used to indicate whether all the cells where the terminal device has resided are synchronized with the packet data convergence protocol. When at least one cell among all the cells where the terminal device has resided is not synchronized with the packet data convergence protocol, the resident cell information indicates that the terminal device needs to be reconfigured with a multicast broadcast wireless bearer; or, the resident cell information is used to indicate whether the last cell where the terminal device resided was synchronized with the packet data convergence protocol. When the last cell where the terminal device resided was not synchronized with the packet data convergence protocol, the resident cell information indicates that the terminal device needs to be reconfigured with a multicast broadcast wireless bearer.

[0429] In one possible design, the sending unit 1502 is specifically used to send a wireless resource control recovery request message to the second network device, the wireless resource control recovery request message includes indication information; and / or, to send a wireless resource control recovery completion message to the second network device, the wireless resource control recovery completion message includes indication information.

[0430] In one possible design, the receiving unit 1501 is further used to receive a multicast broadcast radio bearer reconfigured for the terminal device from the second network device.

[0431] For another example: for the above scenario of the terminal device sending instruction information to the second network device, the embodiment of the present application can also provide a communication device that can be applied to the above second network device. Figure 16 shows another structural diagram of the communication device provided by the embodiment of the present application.

[0432] As shown in FIG16 , the communication device may include: a receiving unit 1601 and a sending unit 1602 .

[0433] Among them, the receiving unit 1601 is used to receive indication information from a terminal device, where the terminal device is a terminal device joining a multicast session, and the indication information is used to indicate whether it is necessary to reconfigure the multicast broadcast radio bearer for the terminal device; the sending unit 1602 is used to send the reconfigured multicast broadcast radio bearer to the terminal device when the indication information indicates that the multicast broadcast radio bearer for the terminal device needs to be reconfigured.

[0434] In one possible design, the indication information includes the resident cell information of the terminal device, and the resident cell information is used to indicate whether it is necessary to reconfigure the multicast broadcast radio bearer for the terminal device.

[0435] In one possible design, the resident cell information includes information of all cells where the terminal device has resided. When at least one cell among all the cells where the terminal device has resided is not synchronized with the packet data convergence protocol, the resident cell information indicates that the terminal device needs to be reconfigured with a multicast broadcast wireless bearer; or, the resident cell information is used to indicate whether all the cells where the terminal device has resided are synchronized with the packet data convergence protocol. When at least one cell among all the cells where the terminal device has resided is not synchronized with the packet data convergence protocol, the resident cell information indicates that the terminal device needs to be reconfigured with a multicast broadcast wireless bearer; or, the resident cell information is used to indicate whether the last cell where the terminal device resided was synchronized with the packet data convergence protocol. When the last cell where the terminal device resided was not synchronized with the packet data convergence protocol, the resident cell information indicates that the terminal device needs to be reconfigured with a multicast broadcast wireless bearer.

[0436] In one possible design, the receiving unit 1601 is specifically used to receive a wireless resource control recovery request message from a terminal device, the wireless resource control recovery request message including indication information; and / or, to receive a wireless resource control recovery completion message from a terminal device, the wireless resource control recovery completion message including indication information.

[0437] Similarly, for the above scenario in which the second network device must optionally perform MRB reconfiguration, an embodiment of the present application can also provide a communication device applied to the second network device, which may include a hardware structure and / or software module capable of realizing the functions of the second network device, such as a sending unit, a receiving unit, etc., which will not be repeated here.

[0438] It should be understood that the division of units in the above device is merely a division of logical functions. In actual implementation, they may be fully or partially integrated into a single physical entity, or physically separated. Furthermore, the units in the device may be implemented entirely in the form of software invoked through processing elements, entirely in the form of hardware, or partially in the form of software invoked through processing elements, while others may be implemented in the form of hardware.

[0439] For example, each unit can be a separately established processing element, or it can be integrated into a certain chip of the device for implementation. In addition, it can also be stored in a memory in the form of a program, and called by a certain processing element of the device to execute the function of the unit. In addition, all or part of these units can be integrated together, or they can be implemented independently. The processing element described here can also be called a processor, which can be an integrated circuit with signal processing capabilities. In the implementation process, each step of the above method or each of the above units can be implemented by the integrated logic circuit of the hardware in the processor element or in the form of software called by the processing element.

[0440] In one example, the unit in any of the above devices can be one or more integrated circuits configured to implement the above method, such as: one or more ASICs, or, one or more DSPs, or, one or more FPGAs, or a combination of at least two of these integrated circuit forms.

[0441] For another example, when the units in the device can be implemented in the form of a processing element scheduling program, the processing element can be a general-purpose processor, such as a CPU or other processor that can call programs. For another example, these units can be integrated together and implemented in the form of a system-on-a-chip (SOC).

[0442] The above-mentioned unit for receiving is an interface circuit or input circuit of the device, which is used to receive signals from other devices. For example, when the device is implemented in the form of a chip, the receiving unit is the interface circuit or input circuit of the chip used to receive signals from other chips or devices. When the communication device includes a unit for sending, the unit for sending is an interface circuit or output circuit of the device, which is used to send signals to other devices. For example, when the device is implemented in the form of a chip, the sending unit is the interface circuit or output circuit of the chip used to send signals to other chips or devices.

[0443] For example, an embodiment of the present application may further provide a communication device that can be applied to the first network device or the second network device, or a terminal device. The communication device may include: a processor and an interface circuit. The processor may include one or more processors.

[0444] When the communication device is applied to a first network device, the processor is used to communicate with other devices through the interface circuit and execute the various steps executed by the first network device in the above method.

[0445] When the communication device is applied to the second network equipment, the processor is used to communicate with other devices through the interface circuit and execute the various steps executed by the second network equipment in the above method.

[0446] When the communication device is applied to a terminal device, the processor is used to communicate with other devices through the interface circuit and execute the various steps executed by the terminal device in the above method.

[0447] In one implementation, the units for implementing the corresponding steps of the above methods in the first network device, the second network device, or the terminal device can be implemented in the form of a processing element scheduler. For example, the apparatus for the first network device, the second network device, or the terminal device can include a processing element and a storage element, and the processing element calls a program stored in the storage element to execute the method executed by the first network device or the second network device in the above method embodiment. The storage element can be a storage element on the same chip as the processing element, that is, an on-chip storage element.

[0448] In another implementation, the program for executing the method executed by the first network device or the second network device, or the terminal device, in the above method can be stored in a memory element on a different chip from the processing element, i.e., an off-chip memory element. In this case, the processing element calls or loads the program from the off-chip memory element to the on-chip memory element to call and execute the method executed by the first network device or the second network device, or the terminal device, in the above method embodiment.

[0449] For example, an embodiment of the present application may further provide a communication device, which may include a processor for executing computer instructions stored in a memory. When the computer instructions are executed, the device performs the method performed by the first network device or the second network device, or the terminal device. The memory may be located within the communication device or may be located outside the communication device. The processor may include one or more.

[0450] In another implementation, the unit implementing each step of the above method in the first network device or the second network device, or the terminal device may be configured as one or more processing elements. These processing elements may be correspondingly provided on the first network device or the second network device, or the terminal device. The processing elements here may be integrated circuits, such as one or more ASICs, one or more DSPs, one or more FPGAs, or a combination of these integrated circuits. These integrated circuits may be integrated together to form a chip.

[0451] The units implementing each step of the above method in the first network device or the second network device, or in the terminal device, can be integrated together and implemented in the form of a system-on-chip (SOC), with the SOC chip used to implement the corresponding method. The chip can integrate at least one processing element and a storage element, with the processing element invoking a program stored in the storage element to implement the corresponding method; alternatively, the chip can integrate at least one integrated circuit to implement the corresponding method; alternatively, a combination of the above implementation methods can be used, with the functions of some units implemented by the processing element invoking a program, and the functions of some units implemented by an integrated circuit.

[0452] The processing element here is the same as described above, and can be a general-purpose processor, such as a CPU, or one or more integrated circuits configured to implement the above method, such as: one or more ASICs, or one or more microprocessors DSPs, or one or more FPGAs, etc., or a combination of at least two of these integrated circuit forms.

[0453] A storage element may be a memory or a collective term for multiple storage elements.

[0454] For example, an embodiment of the present application also provides a chip system, which can be applied to the above-mentioned first network device or second network device, or terminal device. The chip system includes one or more interface circuits and one or more processors; the interface circuit and the processor are interconnected by lines; the processor receives and executes computer instructions from the memory of the electronic device through the interface circuit to implement the method executed by the first network device or the second network device, or the terminal device corresponding to the above method embodiment. Among them, for the first network device or the second network device, or the terminal device, the electronic device can be the network device or the terminal device itself or a device in itself, or it can also be other devices that communicate with the network device or the terminal device.

[0455] Through the description of the above implementation methods, technical personnel in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional modules is used as an example. In actual applications, the above-mentioned functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0456] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the modules or units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0457] The units described as separate components may or may not be physically separate, and the components shown as units may be one physical unit or multiple physical units, that is, they may be located in one place or distributed in multiple places. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0458] In addition, the functional units in the various embodiments of the present application may be integrated into a single processing unit, or each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0459] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a readable storage medium. Based on this understanding, the technical solution of the embodiment of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, such as a program. The software product is stored in a program product, such as a computer-readable storage medium, and includes a number of instructions to enable a device (which can be a single-chip microcomputer, chip, etc.) or a processor (processor) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a ROM, a RAM, a magnetic disk, or an optical disk.

[0460] For example, an embodiment of the present application may also provide a computer-readable storage medium, including: computer software instructions; when the computer software instructions are executed in a first network device, or in a chip built into the first network device, the first network device may execute the method executed by the first network device as described in the aforementioned embodiment.

[0461] Alternatively, when the computer software instructions are executed in the second network device or in a chip built into the second network device, the second network device is caused to execute the method executed by the second network device as described in the foregoing embodiment.

[0462] Alternatively, when the computer software instructions are executed in the terminal device or in a chip built into the terminal device, the terminal device executes the method executed by the terminal device as described in the above embodiment.

[0463] Optionally, an embodiment of the present application further provides a communication device. Figure 17 shows another structural schematic diagram of the communication device provided in an embodiment of the present application. As shown in Figure 17, the communication device may include: a transceiver unit 1701 and a processing unit 1702. The transceiver unit 1701 can be used to send and receive information, or to communicate with other network elements. The processing unit 1702 can be used to process data. For example, the device can implement the method executed by the first network device or the second network device, or the terminal device, as described above, through the transceiver unit 1701 and the processing unit 1702.

[0464] Optionally, an embodiment of the present application further provides a computer program product, which, when executed, can implement the method executed by the above-mentioned first network device or second network device, or terminal device.

[0465] Based on the above embodiments, an embodiment of the present application also provides a communication system, including: a first network device and a second network device; the first network device executes the method executed by the first network device as described in the above embodiments; the second network device executes the method executed by the second network device as described in the above embodiments.

[0466] An embodiment of the present application also provides a communication system, including: a terminal device and a second network device; the terminal device executes the method executed by the terminal device as described in the aforementioned embodiment; the second network device executes the method executed by the second network device as described in the aforementioned embodiment.

[0467] The above is only a specific embodiment of the present application, but the scope of protection of this application is not limited to this. Any changes or substitutions within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A communication method, characterized in that: The method is applied to a first network device, and the method includes: Sending a radio resource control release message to a terminal device that joins the multicast session, wherein the radio resource control release message is used to instruct the terminal device to release to a non-connected state; Send indication information to the second network device, where the indication information is used to indicate whether it is necessary to reconfigure the multicast broadcast radio bearer for the terminal device.

2. The method according to claim 1, characterized in that When the terminal device is released to a non-connected state to receive a multicast service, the indication information indicates that a multicast broadcast radio bearer needs to be reconfigured for the terminal device; Alternatively, when the multicast session joined by the terminal device temporarily has no data or the multicast session is deactivated, the indication information indicates that it is not necessary to reconfigure the multicast broadcast radio bearer for the terminal device.

3. The method according to claim 1 or 2, characterized in that: The indication information is specifically used to indicate whether the terminal device is released to a non-connected state to receive a multicast service; Alternatively, the indication information is specifically used to indicate that the terminal device is released to receive multicast service information in a non-connected state; Alternatively, the indication information includes: suspension configuration information, and the suspension configuration information is used to indicate that the terminal device is released to receive multicast service information in a non-connected state.

4. The method according to claim 3, characterized in that The indication information includes the radio resource control connection release message, and the radio resource control connection release message includes the suspension configuration information.

5. The method according to any one of claims 1 to 4, characterized in that: The method further comprises: Determine capability information of the second network device, the capability information including whether to support sending multicast services for terminal devices in a non-connected state; The sending the indication information to the second network device includes: When the second network device supports sending multicast services to terminal devices in a non-connected state, the indication information is sent to the second network device.

6. The method according to claim 5, characterized in that The determining the capability information of the second network device includes: When establishing or modifying the Xn interface with the second network device, determining capability information of the second network device; Alternatively, determining the capability information of the second network device according to a terminal device context migration request message from the second network device; Alternatively, the capability information of the second network device is determined according to the operation, maintenance and management configuration information.

7. The method according to any one of claims 1 to 6, characterized in that: The sending the indication information to the second network device includes: Sending a terminal device context migration response message corresponding to the terminal device to the second network device, wherein the terminal device context migration response message includes the indication information; Alternatively, the indication information is sent to at least one network device within the wireless coverage range of the first network device, where the at least one network device includes the second network device; Alternatively, the indication information is sent to the second network device via a paging message.

8. A communication method, characterized in that: The method is applied to a second network device, and the method includes: Receiving indication information from a first network device, the indication information being used to indicate whether a multicast broadcast radio bearer needs to be reconfigured for a terminal device, the terminal device being a terminal device that joins a multicast session; When the indication information indicates that the multicast broadcast radio bearer needs to be reconfigured for the terminal device, the reconfigured multicast broadcast radio bearer is sent to the terminal device.

9. The method according to claim 8, characterized in that When the terminal device is released to a non-connected state to receive a multicast service, the indication information indicates that a multicast broadcast radio bearer needs to be reconfigured for the terminal device; Alternatively, when the multicast session joined by the terminal device temporarily has no data or the multicast session is deactivated, the indication information indicates that it is not necessary to reconfigure the multicast broadcast radio bearer for the terminal device.

10. The method according to claim 8 or 9, characterized in that: The indication information is specifically used to indicate whether the terminal device is released to a non-connected state to receive a multicast service; Alternatively, the indication information is specifically used to indicate that the terminal device is released to receive multicast service information in a non-connected state; Alternatively, the indication information includes: suspension configuration information, the suspension configuration information is used to indicate that the terminal device is released to Multicast service information received in a non-connection state; When the indication information indicates that the terminal device is released to a non-connected state to receive a multicast service, the sending of a reconfigured multicast broadcast radio bearer to the terminal device includes: Sending to the terminal device a multicast broadcast radio bearer reconfigured for all multicast services of the terminal device; Alternatively, when the indication information indicates that the terminal device is released to receive multicast service information in a non-connected state, or the indication information includes the suspension configuration information, sending a reconfigured multicast broadcast radio bearer to the terminal device includes: A multicast broadcast radio bearer reconfigured for the multicast service that the terminal device is released to receive in a connected state is sent to the terminal device.

11. The method according to claim 10, characterized in that The indication information includes a radio resource control connection release message, and the radio resource control connection release message includes the suspension configuration information.

12. The method according to any one of claims 8 to 11, characterized in that: The second network device supports sending multicast services to terminal devices in a non-connected state.

13. The method according to claim 12, characterized in that The method further comprises: When the Xn interface between the first network device and the first network device is established or modified, sending capability information of the second network device to the first network device; Alternatively, sending a terminal device context migration request message to the first network device, wherein the terminal device context migration request message includes capability information of the second network device; Alternatively, the operation, maintenance and management configuration information includes capability information of the second network device; The capability information includes whether to support sending multicast services for terminal devices in a non-connected state.

14. The method according to any one of claims 8 to 13, characterized in that: The receiving indication information from the first network device includes: receiving a terminal device context migration response message corresponding to the terminal device sent from the first network device, wherein the terminal device context migration response message includes the indication information; Alternatively, a paging message sent from the first network device is received, where the paging message includes the indication information.

15. A communication method, characterized in that: The method is applied to a terminal device, and the method comprises: Receiving a radio resource control release message from a first network device, wherein the radio resource control release message is used to instruct the terminal device to release to a non-connected state; Send indication information to the second network device, where the indication information is used to indicate whether it is necessary to reconfigure the multicast broadcast radio bearer for the terminal device.

16. The method according to claim 15, characterized in that The indication information includes the resident cell information of the terminal device, and the resident cell information is used to indicate whether it is necessary to reconfigure the multicast broadcast radio bearer for the terminal device.

17. The method according to claim 16, characterized in that The resident cell information includes information of all cells where the terminal device has resided, and when at least one cell in all the cell information where the terminal device has resided is not synchronized with the packet data convergence protocol, the resident cell information indicates that a multicast broadcast radio bearer needs to be reconfigured for the terminal device; Alternatively, the resident cell information is used to indicate whether all cells where the terminal device has resided are synchronized with the packet data convergence protocol. When at least one cell among all cells where the terminal device has resided is not synchronized with the packet data convergence protocol, the resident cell information indicates that a multicast broadcast radio bearer needs to be reconfigured for the terminal device. Alternatively, the resident cell information is used to indicate whether the last cell where the terminal device resided was packet data convergence protocol synchronized. When the last cell where the terminal device resided was not packet data convergence protocol synchronized, the resident cell information indicates that the multicast broadcast radio bearer needs to be reconfigured for the terminal device.

18. The method according to any one of claims 15 to 17, characterized in that: The sending the indication information to the second network device includes: Sending a radio resource control restoration request message to the second network device, where the radio resource control restoration request message includes the indication information; And / or, sending a radio resource control recovery completion message to the second network device, wherein the radio resource control recovery completion message includes the indication information.

19. The method according to any one of claims 15 to 18, characterized in that: The method further comprises: Receive a multicast broadcast radio bearer reconfigured for the terminal device from the second network device.

20. A communication method, characterized in that: The method is applied to a second network device, and the method includes: Receiving indication information from a terminal device, where the terminal device is a terminal device that joins a multicast session, and the indication information is used to indicate whether a multicast broadcast radio bearer needs to be reconfigured for the terminal device; When the indication information indicates that the multicast broadcast radio bearer needs to be reconfigured for the terminal device, the reconfigured multicast broadcast radio bearer is sent to the terminal device.

21. The method according to claim 20, characterized in that The indication information includes the resident cell information of the terminal device, and the resident cell information is used to indicate whether it is necessary to reconfigure the multicast broadcast radio bearer for the terminal device.

22. The method according to claim 21, characterized in that The resident cell information includes information of all cells where the terminal device has resided, and when at least one cell in all the cell information where the terminal device has resided is not synchronized with the packet data convergence protocol, the resident cell information indicates that a multicast broadcast radio bearer needs to be reconfigured for the terminal device; Alternatively, the resident cell information is used to indicate whether all cells where the terminal device has resided are synchronized with the packet data convergence protocol. When at least one cell among all cells where the terminal device has resided is not synchronized with the packet data convergence protocol, the resident cell information indicates that a multicast broadcast radio bearer needs to be reconfigured for the terminal device. Alternatively, the resident cell information is used to indicate whether the last cell where the terminal device resided was packet data convergence protocol synchronized. When the last cell where the terminal device resided was not packet data convergence protocol synchronized, the resident cell information indicates that the multicast broadcast radio bearer needs to be reconfigured for the terminal device.

23. The method according to any one of claims 20 to 22, characterized in that: The receiving instruction information from the terminal device includes: receiving a radio resource control restoration request message from the terminal device, wherein the radio resource control restoration request message includes the indication information; And / or, receiving a radio resource control recovery completion message from the terminal device, the radio resource control recovery completion message including the indication information.

24. A communication device, characterized in that: The device comprises: A sending unit, used to send a radio resource control release message to a terminal device that joins a multicast session, wherein the radio resource control release message is used to instruct the terminal device to release to a non-connected state; The sending unit is further used to send indication information to the second network device, where the indication information is used to indicate whether it is necessary to reconfigure the multicast broadcast radio bearer for the terminal device.

25. A communication device, characterized in that: The device comprises: A receiving unit, configured to receive indication information from a first network device, wherein the indication information is used to indicate whether a multicast broadcast radio bearer needs to be reconfigured for a terminal device, wherein the terminal device is a terminal device that joins a multicast session; A sending unit is used to send a reconfigured multicast broadcast radio bearer to the terminal device when the indication information indicates that the multicast broadcast radio bearer needs to be reconfigured for the terminal device.

26. A communication device, characterized in that: The device comprises: A receiving unit, configured to receive a radio resource control release message from a first network device, wherein the radio resource control release message is used to instruct the terminal device to release to a non-connected state; A sending unit is used to send indication information to the second network device, where the indication information is used to indicate whether it is necessary to reconfigure the multicast broadcast radio bearer for the terminal device.

27. A communication device, characterized in that: The device comprises: A receiving unit, configured to receive indication information from a terminal device, wherein the terminal device is a terminal device that joins a multicast session, and the indication information is used to indicate whether a multicast broadcast radio bearer needs to be reconfigured for the terminal device; A sending unit is used to send a reconfigured multicast broadcast radio bearer to the terminal device when the indication information indicates that the multicast broadcast radio bearer needs to be reconfigured for the terminal device.

28. A communication device, characterized in that: include: A processor, configured to execute computer instructions stored in a memory, wherein when the computer instructions are executed, the device executes a method as described in any one of claims 1 to 7, or a method as described in any one of claims 8 to 14.

29. A communication device, characterized in that: include: A processor, configured to execute computer instructions stored in a memory, wherein when the computer instructions are executed, the device executes a method as described in any one of claims 15 to 19, or a method as described in any one of claims 20 to 23.

30. A computer-readable storage medium, characterized in that: include: Computer software instructions; When the computer software instructions are executed in a network device or a chip built into the network device, the network device executes the method according to any one of claims 1 to 7, or the method according to any one of claims 8 to 14.

31. A computer-readable storage medium, characterized in that: include: Computer software instructions; When the computer software instructions are executed in a terminal device or a chip built into the terminal device, the terminal device executes the method according to any one of claims 15 to 19.

32. A computer-readable storage medium, characterized in that: include: Computer software instructions; When the computer software instructions are executed in a network device or a chip built into the network device, the network device executes the method according to any one of claims 20 to 23.

33. A communication system, characterized in that: include: a first network device and a second network device; The first network device executes the method according to any one of claims 1 to 7; The second network device executes the method according to any one of claims 8 to 14.

34. A communication system, characterized in that: include: The terminal device and the second network device; The terminal device executes the method according to any one of claims 15 to 19; The second network device executes the method according to any one of claims 20-23.

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