Communication methods and devices

Abstract

An embodiment of the present application provides a communication method and a communication device. The method includes: a terminal device receives first information, the first information being related to a status of a first multicast service and / or the first information being related to configuration information of the first multicast service in a second cell; the terminal device determines whether to send first request information to the second cell based on the first information, where the first request information is used by the terminal device to establish or resume an RRC connection; the terminal device is a terminal device that receives the first multicast service, is a terminal device in a radio resource control (RRC) unconnected state, and is a terminal device that performs handover or reselection from the first cell to the second cell. The technical solution provided in the present application avoids resource waste caused by the terminal device unnecessarily entering a connected state during the handover or reselection process.

Description

[Technical Field]

[0001] [Related Applications] This application claims priority to Chinese Patent Application No. 202210939716.2, filed with the State Intellectual Property Office of China on August 5, 2022, entitled "COMMUNICATION METHOD AND COMMUNICATION APPARATUS," which is incorporated herein by reference in its entirety.

[0002] [Technical field] TECHNICAL FIELD Embodiments of the present application relate to the field of communications, and more particularly to a communication method and a communication device. [Background technology]

[0003] A multicast and broadcast service (MBS) is a service directed to multiple user equipment (UE), such as a live broadcast service, a public security service, or a batch software update service. The MBS service is provided by a data server. The data server transmits the MBS data to a core network device, which then transmits the MBS data to a base station. Finally, the base station transmits the MBS data to at least one UE that receives the MBS service.

[0004] When the core network transmits MBS data to the base station, the transmission of the MBS service is performed using a common transmission channel MBS session, and each MBS session can include at least one MBS QoS flow. However, when transmitting MBS data from the base station to the terminal device, data packets are transmitted using an MBS radio bearer. There are two transmission modes for one MBS radio bearer. In the first mode, a point-to-multipoint (PTM) transmission method can be used. In the second mode, a point-to-point (PTP) transmission method can be used.

[0005] Multicast services are designed for services with high QoS requirements. Multicast services require group management. Multicast and unicast services can provide the same QoS level. Specifically, multicast services require the core network to manage the joining and leaving of terminal devices. Transmission between the core network and base stations relies on PDU sessions, and a new MBS QoS flow is introduced. The radio access network (RAN) can transmit data to terminal devices using PTP and PTM transmission methods, and dynamic switching between PTP and PTM, controlled by the RAN, is supported. In 3GPP Release 17, multicast services can only be provided to terminal devices in a radio resource control (RRC) connected state. The access network and core network must maintain information about terminal devices corresponding to multicast service groups. Summary of the Invention

[0006] An embodiment of the present application provides a communication method, which can avoid initiating unnecessary request information for connection establishment or connection resumption when a terminal device performs handover or reselection from a first cell, thereby reducing resource consumption.

[0007] According to a first aspect, there is provided a communication method, including: a terminal device receives first information, the first information relating to a state of a first multicast service and / or the first information relating to configuration information of the first multicast service in a second cell; the terminal device determines, based on the first information, whether to transmit first request information to the second cell, where the first request information is used by the terminal device to establish or resume an RRC connection; the terminal device is a terminal device that receives the first multicast service, is a terminal device in a radio resource control (RRC) non-connected state, and performs handover or reselection from the first cell to the second cell; according to the communication method provided herein, the terminal device receives the first information and, based on the first information, determines whether to transmit first request information to the second cell, where the first request information is used by the terminal device to perform handover or reselection from the first cell to the second cell in order to establish or resume an RRC connection; the first information relating to the state of the first multicast service and / or the first information relating to configuration information of the first multicast service in the second cell. This makes it possible to avoid initiating unnecessary request information for establishing or resuming a connection when the terminal device performs handover or reselection from the first cell, thereby reducing resource consumption.

[0008] Furthermore, when the terminal device performs handover or reselection from the first cell to the second cell, direct access to the terminal device may occupy access resources of the network. Therefore, the method provided in this application can further reduce network congestion.

[0009] In some possible implementations of the first aspect, determining whether the terminal device should transmit first request information to the second cell based on the first information includes: if the state of the first multicast service is an active state, the terminal device transmits the first request information to the second cell, or if the state of the first multicast service is an inactive state, the terminal device remains in a disconnected state.

[0010] According to the above solution, when the first information is related to the state of the first multicast service, the terminal device determines based on the state of the first multicast service whether to send the first request information to the second cell or whether the terminal device will continue to remain in a disconnected state, thereby avoiding the waste of resources caused by the terminal device initiating access without determining the service state and then stopping the service after entering a connected state in the second cell.

[0011] Regarding the first aspect, in some possible implementations, determining whether the terminal device should send first request information to the second cell based on the first information includes: if the configuration information of the first multicast service in the first cell is different from the configuration information of the first multicast service in the second cell, the terminal device sends the first request information to the second cell; if the configuration information of the first multicast service in the first cell is the same as the configuration information of the first multicast service in the second cell, the terminal device remains in a disconnected state.

[0012] According to the above solution, if the first information is related to the configuration information of the first multicast service in the second cell, the terminal device determines whether to send the first request information to the second cell or whether the terminal device continues to remain in a disconnected state based on the configuration information of the first multicast service in the second cell, thereby avoiding resource waste caused by the terminal device initiating access without determining whether the configuration information is the same and then being released after entering a connected state in the second cell.

[0013] Regarding the first aspect, in some possible implementations, the terminal device determining whether to send first request information to the second cell based on the first information includes: if the configuration information of the first multicast service in the first cell is the same as the configuration information of the first multicast service in the second cell and the state of the first multicast service is in an active state, the terminal device sends the first request information to the second cell, and if the configuration information of the first multicast service in the first cell is the same as the configuration information of the first multicast service in the second cell and the state of the first multicast service is in an inactive state, the terminal device remains in a disconnected state.

[0014] According to the above solution, when the first information is related to the configuration information of the first multicast service in the second cell and the state of the first multicast service, the terminal device determines whether to send the first request information to the second cell or whether the terminal device will remain in a disconnected state based on the configuration information of the first multicast service and the state of the first multicast service in the second cell, thereby avoiding resource waste caused by the terminal device being released after entering a connected state in the second cell.

[0015] Regarding the first aspect, in some possible implementations, the terminal device receives a first paging message, and the first paging message includes an identifier of the first multicast service.

[0016] According to the above solution, when the terminal device remains in a disconnected state and receives a first paging message including an identifier of a first multicast service, the terminal device determines that the first multicast service is activated or that the terminal device needs to enter a connected state. For example, the terminal device sends first request information to a second cell based on the first paging message and enters a connected state.

[0017] Regarding the first aspect, in some possible implementations, the terminal device receives second information, and the second information is used to determine that the second cell does not provide the first multicast service to the terminal device in an unconnected state.

[0018] Based on the above solution, the terminal device receives second information, which may be from the first cell or the second cell, and the second information is used to determine that the second cell will not provide the first multicast service to the terminal device in an unconnected state. In this case, the terminal device further determines whether to send the first request information to the second cell based on the status of the first multicast service and / or configuration information of the first multicast service in the second cell.

[0019] The second information may directly indicate that the second cell does not support the multicast service in the disconnected state, or the second information may indicate that the second cell supports the multicast service in the disconnected state but is in the disconnected state, and the multicast service provided by the second cell does not include the first multicast service, which is not limited in the present application.

[0020] With reference to the first aspect, in some possible implementations, if the second information includes configuration information of a multicast control channel (MCCH) of the second cell, the terminal device acquires the third information based on the MCCH configuration information. Here, if the third information includes the MCCH information of the second cell and the MCCH information does not include an identifier of the first multicast service, or if the terminal device fails to acquire the third information based on the MCCH configuration information. According to the above solution, if the second information includes the MCCH configuration information of the second cell, it indicates that the second cell supports a multicast service in an unconnected state. The terminal device acquires the third information based on the MCCH configuration information. Here, the third information includes the MCCH information. If the MCCH information does not include an identifier of the first multicast service, it indicates that the second cell supports a multicast service in an unconnected state but does not provide the first multicast service to the terminal device in an unconnected state. Alternatively, if the second information received by the terminal device includes MCCH configuration information but the terminal device fails to acquire the third information based on the MCCH configuration information, it indicates that the second cell does not provide a multicast service to the terminal device in an unconnected state.

[0021] In relation to the first aspect, in some possible implementations, the first information is conveyed in at least one message of a paging message, a system information block (SIB), and MCCH information. Based on the above solution, the first information is conveyed in at least one message of a paging message, a system information block (SIB), and MCCH information, and is transmitted to the terminal device. The terminal device can receive the first information without entering a connected state.

[0022] Optionally, the terminal device may acquire the first information when the terminal device is in a connected state, or may acquire the first information using an RRC release message, which is not limited in the present application.

[0023] In relation to the first aspect, in some possible implementations, when the first information relates to configuration information of the first multicast service in the second cell, the first information includes PDCP synchronization information of the second cell and / or PDCP synchronization information of the first cell, and the synchronization information includes whether PDCP is synchronized or not synchronized.

[0024] According to the above solution, if the first information relates to configuration information of the first multicast service in the second cell, the first information may include PDCP synchronization information of the second cell and / or PDCP synchronization information of the first cell, where the synchronization information includes whether the PDCP of the second cell is synchronized or not synchronized and / or whether the PDCP of the first cell is synchronized or not synchronized. The terminal device further determines a processing method for the PDCP layer based on the PDCP synchronization information of the second cell and / or the PDCP synchronization information of the first cell.

[0025] Regarding the first aspect, in some possible implementations, if the synchronization information includes that the PDCP of the second cell and / or the PDCP of the first cell are not synchronized, the terminal device resets a PDCP entity or a PDCP variable, and / or the terminal device discards buffered PDCP data packets or delivers the buffered PDCP data packets to an upper layer.

[0026] Based on the above solutions, if the PDCP of the second cell is not synchronized and / or the PDCP of the first cell is not synchronized, the terminal device can reset the PDCP entity or PDCP variables and / or discard buffered PDCP data packets or deliver the buffered PDCP data packets to an upper layer.

[0027] Optionally, if the PDCP of the second cell is not synchronized and / or the PDCP of the first cell is not synchronized, the terminal device sends first request information to the second cell, and after the terminal device and the second cell enter a connected state, the terminal device receives the PDCP configuration in the second cell.

[0028] According to a second aspect, a communication method is provided. The method includes: a first cell determines first information, the first information relating to a state of a first multicast service; the first cell transmits the first information to a terminal device, the first information being used by the terminal device to determine whether to transmit first request information to a second cell, the first request information being used by the terminal device to establish or resume an RRC connection; the terminal device is a terminal device that receives the first multicast service, is a terminal device in a radio resource control (RRC) unconnected state, and is a terminal device that performs handover or reselection from the first cell to the second cell.

[0029] It should be understood that all steps and processing processes of the first cell in this application may be performed by the first network device serving the first cell.

[0030] Regarding the second aspect, in some possible implementations, the state of the first multicast service includes an active state or an inactive state.

[0031] Regarding the second aspect, in some possible implementations, the first cell transmits second information to the terminal device, and the second information is used to determine that the second cell will not provide the first multicast service to the terminal device in an unconnected state.

[0032] In relation to the second aspect, in some possible implementations, the first information is conveyed in at least one of a paging message, a system information block (SIB), and MCCH information.

[0033] Based on the above solution, the first information is carried in at least one message of a paging message, a system information block (SIB), and MCCH information, and is transmitted to the terminal device, which can receive the first information without entering a connected state.

[0034] Optionally, the terminal device may acquire the first information when the terminal device is in a connected state, or may acquire the first information using an RRC release message, which is not limited in the present application.

[0035] According to a third aspect, there is provided a communication method. The method includes: a second cell determining second information, the second information being used to determine that the second cell will not provide a first multicast service to a terminal device in a disconnected state; and the second cell transmitting the second information to the terminal device. The terminal device is a terminal device that receives the first multicast service, is a terminal device in a radio resource control (RRC) disconnected state, and is a terminal device that performs handover or reselection from the first cell to the second cell.

[0036] It should be understood that all steps and processing processes of the second cell in this application may be performed by a second network device serving the second cell.

[0037] Regarding the third aspect, in some possible implementations, the second cell transmits third information to the terminal device, where the third information includes MCCH information of the second cell, and the MCCH information does not include an identifier of the first multicast service.

[0038] Regarding the third aspect, in some possible implementations, the second cell sends configuration information of the first multicast service in the second cell to the first network device, and the configuration information is used to determine the first information, where the first cell and the second cell are neighboring cells, or the second cell is a cell within the range of the first cell, or the first cell and the second cell are cells in the same RNA.

[0039] Regarding the third aspect, in some possible implementations, the second cell transmits PDCP synchronization information of the second cell to the first network device, and the synchronization information includes whether the PDCP is synchronized or not synchronized.

[0040] According to a fourth aspect, there is provided a communication method. The method includes: a first network device determines first information, the first information relating to configuration information of a first multicast service in a second cell; the first network device transmits the first information to a terminal device, the first information being used by the terminal device to determine whether to transmit first request information to the second cell, the first request information being used by the terminal device to establish or resume an RRC connection; the terminal device is a terminal device that receives the first multicast service, is a terminal device in a radio resource control (RRC) unconnected state, and is a terminal device that performs handover or reselection from the first cell to the second cell.

[0041] Regarding the fourth aspect, in some possible implementations, the first network device receives configuration information of the first multicast service in the second cell, and the configuration information is used to determine the first information.

[0042] Regarding the fourth aspect, in some possible implementations, the first information includes PDCP synchronization information of the second cell, and the synchronization information includes whether the PDCP is synchronized or not synchronized.

[0043] In relation to the fourth aspect, in some possible implementations, the first information is conveyed in at least one of a paging message, a system information block (SIB), and MCCH information.

[0044] Based on the above solution, the first information is carried in at least one message of a paging message, a system information block (SIB), and MCCH information, and is transmitted to the terminal device, which can receive the first information without entering a connected state.

[0045] Optionally, the terminal device may acquire the first information when the terminal device is in a connected state, or may acquire the first information using an RRC release message, which is not limited in the present application.

[0046] According to a fifth aspect, there is provided a communications device. A transceiver unit receives first information, the first information relating to a status of a first multicast service and / or the first information relating to configuration information of the first multicast service in a second cell. A processing unit determines whether to transmit first request information to the second cell based on the first information, the first request information being used by a terminal device to establish or resume an RRC connection. The transceiver unit is a transceiver unit that receives the first multicast service, the transceiver unit and the processing unit are terminal devices in a radio resource control (RRC) disconnected state, and the terminal device is a terminal device that performs handover or reselection from the first cell to the second cell.

[0047] Regarding the fifth aspect, in some possible implementations, the processing unit determining whether to send first request information to the second cell based on the first information includes: if the state of the first multicast service is an active state, the transceiver unit sends the first request information to the second cell, or if the state of the first multicast service is an inactive state, the processing unit remains in a disconnected state.

[0048] Regarding the fifth aspect, in some possible implementations, the processing unit determining whether to send first request information to the second cell based on the first information includes: if the configuration information of the first multicast service in the first cell is different from the configuration information of the first multicast service in the second cell, the transceiver unit sends the first request information to the second cell; if the configuration information of the first multicast service in the first cell is the same as the configuration information of the first multicast service in the second cell, the processing unit remains in a disconnected state.

[0049] Regarding the fifth aspect, in some possible implementations, the processing unit's determining whether to send first request information to the second cell based on the first information includes: if the configuration information of the first multicast service in the first cell is the same as the configuration information of the first multicast service in the second cell and the state of the first multicast service is an active state, the transceiver unit sends the first request information to the second cell, and if the configuration information of the first multicast service in the first cell is the same as the configuration information of the first multicast service in the second cell and the state of the first multicast service is an inactive state, the processing unit remains in a disconnected state.

[0050] Regarding the fifth aspect, in some possible implementations, the transceiver unit receives a first paging message, the first paging message including an identifier of the first multicast service.

[0051] Regarding the fifth aspect, in some possible implementations, the transceiver unit receives second information, and the second information is used to determine that the second cell does not provide the first multicast service to a terminal device in an unconnected state.

[0052] Referring to the fifth aspect, in some possible implementations, when the second information includes configuration information of a multicast control channel (MCCH) of the second cell, the processing unit acquires the third information based on the configuration information of the MCCH, wherein the third information includes the MCCH information of the second cell and the MCCH information does not include an identifier of the first multicast service, or the terminal device fails to acquire the third information based on the configuration information of the MCCH.

[0053] In relation to the fifth aspect, in some possible implementations, the first information is conveyed in at least one of a paging message, a system information block (SIB), and MCCH information.

[0054] In relation to the fifth aspect, in some possible implementations, when the first information relates to configuration information of a first multicast service in a second cell, the first information includes PDCP synchronization information of the first cell and / or PDCP synchronization information of the second cell, and the synchronization information includes whether PDCP is synchronized or not synchronized.

[0055] Regarding the fifth aspect, in some possible implementations, if the synchronization information includes that the PDCP of the first cell and / or the PDCP of the second cell are not synchronized, the processing unit resets a PDCP entity or a PDCP variable, and / or the processing unit discards buffered PDCP data packets or delivers the buffered PDCP data packets to an upper layer.

[0056] According to a sixth aspect, there is provided a communications device. A processing unit determines first information, the first information relating to a state of a first multicast service. A transceiver unit transmits the first information to a terminal device, the first information being used by the terminal device to determine whether to transmit first request information to a second cell, the first request information being used by the terminal device to establish or resume an RRC connection. The terminal device is a terminal device that receives the first multicast service, is a terminal device in a radio resource control (RRC) unconnected state, and is a terminal device that performs handover or reselection from the first cell to the second cell.

[0057] Regarding the sixth aspect, in some possible implementations, the state of the first multicast service includes an active state or an inactive state.

[0058] Regarding the sixth aspect, in some possible implementations, the processing unit transmits second information to the terminal device, and the second information is used to determine that the second cell does not provide the first multicast service to the terminal device in a disconnected state.

[0059] Regarding the sixth aspect, in some possible implementations, the second information includes configuration information of a multicast control channel (MCCH) of the second cell.

[0060] In relation to the sixth aspect, in some possible implementations, the first information is conveyed in at least one of a paging message, a system information block (SIB), and MCCH information.

[0061] Optionally, the transceiver unit may acquire the first information in a connected state, or may acquire the first information using an RRC release message, which is not limited in the present application.

[0062] According to a seventh aspect, there is provided a communications device. The processing unit determines second information, and the second information is used to determine that the second cell will not provide the first multicast service to a terminal device in a disconnected state. The transceiver unit transmits the second information to the terminal device. The terminal device is a terminal device that receives the first multicast service, is a terminal device in a radio resource control (RRC) disconnected state, and is a terminal device that performs handover or reselection from the first cell to the second cell.

[0063] Regarding the seventh aspect, in some possible implementations, the processing unit transmits third information to the terminal device, where the third information includes MCCH information of the second cell, and the MCCH information does not include an identifier of the first multicast service.

[0064] Regarding the seventh aspect, in some possible implementations, the processing unit sends configuration information of the first multicast service in the second cell to the first network device, and the configuration information is used to determine the first information, and the first cell and the second cell are neighboring cells.

[0065] Regarding the seventh aspect, in some possible implementations, the processing unit sends PDCP synchronization information of the second cell to the first network device, and the synchronization information includes whether the PDCP is synchronized or not synchronized.

[0066] According to an eighth aspect, there is provided a communication method. The method includes: a processing unit determines first information, the first information relating to configuration information of a first multicast service in a second cell; a transceiver unit transmits the first information to a terminal device, the first information being used by the terminal device to determine whether to transmit first request information to the second cell, the first request information being used by the terminal device to establish or resume an RRC connection; the terminal device is a terminal device that receives the first multicast service, is a terminal device in a radio resource control (RRC) unconnected state, and is a terminal device that performs handover or reselection from the first cell to the second cell.

[0067] Regarding the eighth aspect, in some possible implementations, the transceiver unit receives configuration information of the first multicast service in the second cell, and the configuration information is used to determine the first information.

[0068] Regarding the eighth aspect, in some possible implementations, the first information includes PDCP synchronization information of the first cell and / or PDCP synchronization information of the second cell, and the synchronization information includes whether the PDCP is synchronized or not synchronized.

[0069] In relation to the eighth aspect, in some possible implementations, the first information is conveyed in at least one message of a paging message, a system information block (SIB), and MCCH information.

[0070] According to a ninth aspect, there is provided a communication device. The present application provides a communication device. The communication device may be a network device or a terminal device. The communication device includes a transceiver, a processor, and a memory. The processor is configured to control the transceiver to receive and transmit signals, the memory is configured to store a computer program, and the processor is configured to invoke and execute the computer program stored in the memory, such that the terminal device performs a method according to any possible implementation of the first aspect, the network device performs a method according to any possible implementation of the second aspect, the network device performs a method according to any possible implementation of the third aspect, or the network device performs a method according to any possible implementation of the fourth aspect.

[0071] Specifically, when the terminal device functions as a transmitting end of information and / or data, the terminal device executes the communication method according to any one of the first aspect and possible implementations of the first aspect to transmit the information and / or data that needs to be transmitted. When the network device is used as a receiving end of information and / or data, the network device can execute the communication method according to possible implementations of the second to fourth aspects.

[0072] According to a ninth aspect, the present application provides a computer-readable storage medium storing instructions that, when executed on a computer, enable the computer to perform a method according to any possible implementation of the first to fourth aspects.

[0073] According to an eleventh aspect, the present application provides a computer program product, the computer program product comprising computer program code which, when executed on a computer, enables the computer to carry out a method according to any possible implementation of the first to fourth aspects.

[0074] According to a twelfth aspect, the present application provides a chip including a processor, the processor being configured to read and execute a computer program stored in a memory to perform a method according to any possible implementation of aspects 1 to 4. Optionally, the chip further includes a memory, the memory and the processor being connected to the memory via a circuit or wire. [Brief explanation of the drawings]

[0075] [Figure 1] FIG. 2 is a diagram of an MBS service transmission process according to an embodiment of the present application. [Figure 2] 3 is a schematic flow chart of receiving broadcast data by a terminal device according to an embodiment of the present application; [Figure 3] 1 is a schematic flowchart of RRC establishment / resumption of a terminal device according to an embodiment of the present application; [Figure 4] FIG. 1 is a diagram of a terminal handover scenario according to an embodiment of the present application. [Figure 5] FIG. 10 is a diagram of another terminal handover scenario according to an embodiment of the present application. [Figure 6] 1 is a diagram of a communication method according to an embodiment of the present application; [Figure 7] FIG. 1 is a diagram of another communication method according to an embodiment of the present application. [Figure 8] FIG. 1 is a diagram of another communication method according to an embodiment of the present application. [Figure 9] FIG. 1 is a diagram of another communication method according to an embodiment of the present application. [Figure 10] FIG. 1 is a diagram of another communication method according to an embodiment of the present application. [Figure 11] FIG. 1 is a diagram of another communication method according to an embodiment of the present application. [Figure 12] 1 is a diagram of a communication architecture to which embodiments of the present application are applicable; [Figure 13] FIG. 1 is a diagram of another communication method according to an embodiment of the present application. [Figure 14] 1 is a diagram of the structure of a communication device according to an embodiment of the present application; [Figure 15]FIG. 2 is a diagram of the structure of another communication device according to an embodiment of the present application; DETAILED DESCRIPTION OF THE INVENTION

[0076] With reference to the accompanying drawings, the technical solutions of the embodiments of the present application are described below.

[0077] The technical solutions of the embodiments of the present application may be applied to various communication systems, such as a global system for mobile communications (GSM) system, a code division multiple access (CDMA) system, a wideband code division multiple access (WCDMA) system, a general packet radio service (GPRS), a long term evolution (LTE) system, an LTE frequency division duplex (FDD) system, an LTE time division duplex (TDD) system, a universal mobile telecommunications system (UMTS), a worldwide interoperability for microwave access (WiMAX) communication system, a future fifth generation (5G) system, or a new radio (NR) system.

[0078] The terminal device in the embodiments of the present application may be a user equipment, an access terminal, a subscriber unit, a subscriber station, a mobile station, a remote station, a remote terminal, a mobile device, a user terminal, a terminal, a wireless communication device, a user agent, or a user equipment. The terminal device may be a cellular phone, a cordless phone, a Session Initiation Protocol (SIP) phone, a Wireless Local Loop (WLL) station, a Personal Digital Assistant (PDA), a handheld device with wireless communication capabilities, a computing device, another processing device connected to a wireless modem, an in-vehicle device, a wearable device, a terminal device in a future 5G network, or a terminal device in a future evolved Public Land Mobile Network (PLMN). This is not limited to the embodiments of the present application.

[0079] It should be understood that in the present embodiment, the terminal device may be a device configured to implement the function of the terminal device, or may be a device that can assist the terminal device in implementing the function, such as a chip system. The device may be installed in the terminal. In the present embodiment of the present application, the chip system may include a chip, or may include a chip and other individual components.

[0080] The network device in the embodiments of the present application may be a device configured to communicate with a terminal device. The network device may be a Base Transceiver Station (BTS) in a Global System for Mobile communications (GSM) system or a Code Division Multiple Access (CDMA) system, a NodeB (NodeB, NB) in a Wideband Code Division Multiple Access (WCDMA) system, an evolved NodeB (eNB or eNodeB) in an LTE system, or a radio controller in a Cloud Radio Access Network (CRAN) scenario. Alternatively, the network device may be a relay station, an access point, an in-vehicle device, a wearable device, a network device in a future 5G network, a network device in a future evolved PLMN network, etc. This is not limited to the embodiments of the present application.

[0081] It should be understood that in the embodiments of the present application, the network device may be a device configured to implement the function of the network device, or may be a device, such as a chip system, that can assist the network device to implement the function. The device may be installed in the network device.

[0082] Furthermore, it should be understood that the specific structure of the entity that executes the method provided in the embodiment of the present application is not particularly limited in the embodiments described below, as long as a program recording the code of the method provided in the embodiment of the present application can be executed to perform communication according to the method provided in the embodiment of the present application. For example, the entity that executes the method provided in the embodiment of the present application may be a terminal device, a network device, or a functional module that is located in the terminal device and the network device and can call and execute a program. The embodiments described herein may be implemented partially, or may be implemented partially or completely after combining the embodiments. This is not a limitation in the present application.

[0083] It should be noted that all steps and processes of the first cell in this application may be performed by a first network device providing service in the first cell, and similarly, all steps and processes of the second cell in this application may be performed by a second network device providing service in the second cell.

[0084] For ease of understanding, the communication nouns or terms used in the embodiments of this application will be explained and described first, and the communication nouns or terms will also be used as part of the inventive content of this application.

[0085] 1. Multicast and broadcast service (MBS) Multicast and Broadcast Services (MBS) are services directed to multiple terminal devices (eg live broadcast services, public security services, or batch software update services).

[0086] FIG. 1 is a diagram of an MBS service transmission process. The MBS service is from a data server. First, the data server transmits MBS data to a core network device, then the core network device transmits the MBS data to an access network device, and finally, the access network device transmits the MBS data to at least one terminal device that receives the MBS service. When the MBS service is transmitted from the core network device to the access network device, the transmission of the MBS service is performed using a common transmission channel MBS session, and each MBS session can include at least one MBS QoS flow. When an MBS data packet is transmitted from the access network device to a terminal device, the transmission of the MBS data packet is performed using an MBS radio bearer. There may be two transmission modes for one MBS radio bearer.

[0087] In the first mode, a point-to-multipoint (PTM) transmission method is used.

[0088] In the second mode, a point-to-point (PTP) transmission method is used.

[0089] 2. Multicast service Multicast services are designed for services with high quality of service (QoS) requirements. Multicast services require group management. Multicast and unicast services can provide the same QoS level. Specifically, multicast services require the core network to manage the joining and leaving of terminal devices. Transmission between the core network and access network devices relies on PDU sessions, and a new MBS QoS flow data flow is introduced. Access network devices support data transmission to terminal devices using PTP and PTM transmission methods and support dynamic switching between PTP and PTM controlled by the access network device. The R17 protocol allows multicast services only to terminal devices in an RRC connected state, and access network devices and core network devices must retain information about terminal devices corresponding to a multicast service group. Conventional technologies also support core network-triggered MBS session deactivation / activation for multicast services, and terminal devices are unaware of the service state.

[0090] 3. Multicast Service Activation / Deactivation Procedures The MBS session deactivation procedure applies only to multicast services. The MBS session deactivation procedure is triggered by the multicast / broadcast session management function (MB-SMF) when it receives a notification from the multicast / broadcast user plane function (MB-UPF) if there is no downlink data available for transmission within a certain period of time, or when it receives a direct request from the application function (AF) or network exposure function (NEF). The MBS session deactivation procedure is used to deactivate the MBS data resources of an NG-RAN node. When triggered by 5GC, the RAN releases the radio resources of the multicast session and stops transmitting multicast session data to the terminal device. The network device may release the terminal device's RRC connection to an idle or inactive state, or may not release the terminal device's RRC connection, and the terminal device is not explicitly notified of the deactivation.

[0091] The MBS session activation procedure applies only to multicast services. The MBS session activation procedure is triggered by the MB-SMF when it receives a notification of downlink MBS data from the MB-UPF or when it receives a request from the AF directly or via the NEF. The MBS session deactivation procedure is used to deactivate the MBS data resources of an NG-RAN node. When triggered by the 5GC, establishment of radio resources for the multicast session is performed and transmission of multicast session data to terminal devices begins. Terminal devices in RRC idle and RRC inactive states and participating in the multicast session are paged.

[0092] 4. Broadcast technology The NR MBS broadcast technology introduces two logical channels: a multicast control channel (MCCH) and a multicast traffic channel (MTCH). The MCCH is used to transmit control information including MTCH configuration information, such as G-RNTI and DRX parameters corresponding to the MTCH. The MCCH is transmitted periodically. The MTCH logical channel carries user data of broadcast services. The MTCH is scheduled via the MCCH. The MTCH configuration is per G-RNTI level or per MBS service level. The access network device uses a group radio network temporary identifier (G-RNTI) to simultaneously schedule service data to multiple terminal devices, and each G-RNTI may be associated with at least one broadcast service.

[0093] 2 is a schematic flowchart of receiving broadcast data by a terminal device. The procedure for receiving a broadcast service by the terminal device is as follows: first, a system message contains control information for transmitting the broadcast service (i.e., MCCH configuration information); the terminal device uses the system message to learn how to receive the MCCH message; the terminal device reads the MCCH message content based on the MCCH configuration information; the MCCH message contains an MBS broadcast configuration message; the MBS broadcast configuration information is a configuration required for receiving the broadcast service, such as MTCH configuration information, G-RNTI, and temporary multicast group identifier (TMGI); finally, the terminal device receives the broadcast service data on the MTCH based on the configuration information.

[0094] 5. Disconnected Radio resource control (RRC) states of a terminal device include an RRC-connected state, an RRC-idle state, and an RRC-inactive state. The RRC-unconnected state in the following embodiments may include at least one of an RRC-idle state or an RRC-inactive state. The RRC-unconnected state may be abbreviated as a unconnected state. The RRC-connected state may be abbreviated as a connected state. The RRC-idle state may be abbreviated as an idle state. The RRC-inactive state may be abbreviated as an inactive state. In the embodiments of the present application, "at least one type" may be one or more types. "multiple types" may be two, three, or more types. This is not a limitation.

[0095] In the following description, an example will be described in which the network device or the access network device is a base station. Specifically, in a process in which a terminal device accesses a base station or a process after the terminal device accesses a base station, the terminal device may perform an RRC establishment process with the base station.

[0096] FIG. 3 shows an RRC establishment or resumption procedure between a terminal device and a base station.

[0097] S310: The terminal device sends RRC establishment / resumption request information to the network device.

[0098] It should be understood that in step S310, the terminal device initiates a request information (for example, the first request information sent by the terminal device to the second cell in this embodiment of the present application) to enter a connected state.

[0099] S320: The network device sends RRC establishment / resume response information to the terminal device.

[0100] Specifically, the network device receives RRC establishment request information from the terminal device, and transmits RRC establishment response information to the terminal device based on the RRC establishment request information.

[0101] It should be understood that the network device receives RRC resumption request information from the terminal device, and transmits RRC resumption response information to the terminal device based on the RRC resumption request information. Alternatively, the network device receives RRC resumption request information from the terminal device, and transmits RRC establishment response information to the terminal device based on the RRC resumption request information, thereby causing the terminal device to re-establish the RRC connection.

[0102] S330: The terminal device sends RRC establishment / resumption completion information to the network device.

[0103] Specifically, the terminal device receives RRC establishment response information from the network device, and performs RRC establishment based on the RRC establishment response information. After determining that the RRC establishment is completed, the terminal device transmits RRC establishment completion information to the network device.

[0104] It should be understood that the terminal device receives the RRC resumption response information from the network device, and performs RRC establishment based on the RRC resumption response information. After determining that the RRC resumption is completed, the terminal device sends the RRC resumption completion information to the network device.

[0105] A simple process of RRC establishment / resumption by a terminal device and a network device is illustrated in Figure 3. For a detailed description, please refer to the prior art.

[0106] After the terminal device establishes an RRC connection with the base station, the RRC state of the terminal device is an RRC connected state, and can then be switched between an RRC idle state, an RRC connected state, and an RRC inactive state.

[0107] According to the R18 standard, a project has been initiated to provide multicast services to terminal devices in an RRC disconnected state and to help terminal devices receive multicast services as much as possible in network congestion scenarios. In a connected state, multicast services can be provided to multiple terminal devices using the PTM method. Therefore, the network transmits only one copy of the data, and multiple terminal devices receive the data collectively. That is, multicast services are provided to all terminal devices in an disconnected state, and only one copy of the data is transmitted, eliminating the need to occupy extra resources.

[0108] There are two ways to provide the configuration information of a disconnected multicast service to a terminal device:

[0109] Method 1: The terminal device acquires the configuration information of the multicast service in a connected state, and the terminal device continues to receive the multicast service in a non-connected state even after the RRC release.

[0110] Method 2: Similar to the broadcast technology method, the network device provides configuration information of the multicast service in the disconnected state on the MCCH, and the terminal device receives data using this configuration information.

[0111] It should be noted that the MCCH may be shared with an existing MCCH for broadcasting, or may be an MCCH designed for multicasting (for example, MC-MCCH). This is not limited in the present application. The MCCH is used to include multicast configuration information, and the name of the MCCH is not limited in the present application. All MCCHs mentioned in the embodiments of the present application are logical channels used to include multicast configuration.

[0112] In both of the above two methods, a terminal device in an unconnected state can receive a multicast service. In method 1, a service received by a terminal device in an unconnected state cannot directly change the configuration information of the service. Compared with the technical solution of method 1, the technical solution of method 2 is more flexible, and method 2 can help the terminal device obtain configuration information at any time. In the solution of method 2, if the MCCH read by the terminal device in an unconnected state includes an identifier (e.g., TMGI) of the received service, the network device can be considered to be providing the corresponding service in an unconnected state mode in an unconnected state. Alternatively, if the MCCH read by the terminal device in an unconnected state does not include an identifier (e.g., TMGI) of the received service, the network device can be considered to be not providing the corresponding service in an unconnected state mode in an unconnected state.

[0113] In the existing standard R17 technology, the active / inactive status of a multicast service is notified only from the core network device to the access network device, but not to the terminal device. If there is no data for a long period of time after the multicast service is deactivated, the network may decide to release the terminal device's RRC connection to the RRC idle or RRC inactive state. In this case, the terminal device in the disconnected mode only needs to perform certain operations that a disconnected terminal device needs to perform, such as measurements and receiving paging and system messages, and does not need to receive additional service data. R18 discusses that, in the background of receiving a multicast service when the network is in a disconnected state, if the terminal device is released to a disconnected state and receives the multicast service, the terminal device must continue to monitor the PDCCH using the G-RNTI to read the multicast service data. In a scenario where a multicast service is deactivated, if the core network device triggers a multicast service deactivation procedure to the access network device, the network device stops transmitting data for a long period of time. However, in this case, if the terminal device continues to monitor the PDCCH, a large amount of unnecessary energy is consumed. Therefore, in a scenario where the network is in a disconnected mode, a multicast service is provided. When a multicast service is in an inactive state, the terminal device needs to be notified of the status of the corresponding service. As a specific reference method, the following solutions can be considered:

[0114] Solution 1: Corresponding to the above method 1 and method 2, the network device pages the terminal device to put it into a connected state and releases the terminal device. During the release, the multicast in the unconnected state is not indicated.

[0115] In Solution 1, the terminal device does not detect the state of the multicast service, and the terminal device performs deactivation based on a network indication indicating whether or not to accept the multicast service in the disconnected state, thereby achieving the purpose of power saving. In Solution 1, the terminal device is released immediately after entering the connected state, which wastes access resources. In this solution, the terminal device does not continue to receive the multicast service in the disconnected state. When the service becomes active again, the terminal device must be further paged to enter the connected state and re-acquire the configuration information for the multicast service. This is contrary to the original purpose of introducing multicast reception to the disconnected terminal device to relieve network congestion. Instead, Solution 1 requires frequent access to the terminal device.

[0116] Solution 2: In Method 1 and Method 2, the network device indicates the state of the multicast service as active / inactive in the RRC release / connection status / paging message.

[0117] In Solution 2, when the terminal device is in a connected state, the network device indicates that it will use the multicast service state to determine whether to receive data when the network is in an RRC disconnected state. If the network indicates that the multicast service state is in an inactive state, the terminal device may not monitor data. If the multicast service state is then in an active state, the terminal device can determine whether it is a multicast service activation scenario (or whether the terminal device needs to enter a connected state) based on a paging message sent by the network. If the corresponding multicast service is active or does not need to enter a connected state, the terminal device needs to start receiving data. The data reception operation by the terminal device also needs to be divided into different modes. There are two types of scenarios based on existing discussions. In the first type, all cells in the RNA can provide the corresponding reception service to the terminal device and can provide the same configuration. In the second type, there is a restriction on whether the same service and the same configuration need to be provided to any cell in the RNA.

[0118] Solution 3: Corresponding to Method 2, the network device indicates on the MCCH that the corresponding state of the multicast service is active or inactive.

[0119] In solution 3, the terminal device can obtain the multicast service state at any time. If the terminal device reads that the multicast service state has become inactive, the terminal device does not monitor data. If the multicast service state is active, the terminal device monitors data. This solution is not limited by whether the RNAs provide the same service and the same configuration. The terminal device determines information about the current cell, which is independent of information about other cells.

[0120] For example, when the indication method is explicit indication, for example, when the content of the MCCH message is TMGI1, TMGI2-deactivated, and TMGI3, it can be seen that the MCCH information directly indicates that the status of the service TMGI2 is inactive.

[0121] In another example, when the indication method is implicit indication, for example, when the content of the MCCH message is TMGI1, TMGI2 (indicating that it is received during release but is not reflected in the MCCH due to deactivation), and TMGI3, it can be seen that TMGI2 is not reflected in the MCCH message, that is, the service state is inactive. Alternatively, when the content of the MCCH message is TMGI1 (including the entire configuration), TMGI2 (including only a partial configuration due to deactivation), and TMGI3 (including the entire configuration), it can be seen that TMGI2 includes only a partial configuration in the MCCH, that is, the service state is inactive.

[0122] Based on the implementation of method 1 for providing a terminal device with a configuration of a multicast service in a disconnected state, as shown in the terminal device handover scenario diagram of Figure 4, the terminal device receives multicast service 1 in a disconnected state in a first cell, and the terminal device moves from the first cell to a second cell.

[0123] It should be understood that the first cell is the source serving cell of the terminal device, and the second cell is the target serving cell of the terminal device.

[0124] Furthermore, in the implementation of Method 1, it should be understood that the following several scenarios may exist in the process of the terminal device moving from the first cell to the second cell.

[0125] Scenario 1: If the second cell is a cell outside the RNA of the first cell, or if the second cell and the first cell belong to the same RNA, it is not guaranteed that the same RNA can provide the same service to different cells, and it is not determined whether the second cell can provide the service to the terminal device. Because the terminal device does not determine whether the target serving cell provides the corresponding service, after the terminal device performs handover or reselection to the second cell, the terminal device enters a connected state and receives the corresponding multicast service or the configuration information of the corresponding service.

[0126] Scenario 2: When the second cell and the first cell belong to the same RNA and the RAN provides the same service to the first cell and the second cell, it is not determined whether the configurations provided by the RAN for the first cell and the second cell are the same. Because the terminal device does not have the configuration information, after performing handover or reselection to the second cell, the terminal device needs to enter a connected state and obtain the configuration information corresponding to the first multicast service (e.g., TMGI1) of the second cell.

[0127] Scenario 3: If the second cell and the first cell belong to the same RNA and the RAN provides the same services and the same configurations to the first cell and the second cell, after handover or reselection from the first cell to the second cell, the terminal device does not need to enter a connected state, but only needs to remain in a non-connected state to receive services.

[0128] Based on the implementation of method 2 for providing a multicast service configuration to a terminal device in a disconnected state, as shown in the terminal device handover diagram of Figure 5, the terminal device obtains the configuration information of TMGI1 received via MCCH in the first cell and moves from the first cell to the second cell.

[0129] In implementing Method 2, it should be understood that the following several scenarios may exist in the process of the terminal device moving from the first cell to the second cell.

[0130] Scenario 4: The TMGI1 does not exist in the MCCH of the second cell, or the MCCH does not exist in the second cell. The terminal device can consider that the second cell is in a disconnected state and does not provide the service TMGI. Therefore, the terminal device needs to enter a connected state to obtain service data.

[0131] Scenario 5: If the MCCH of the second cell includes TMGI1, after performing handover or reselection from the first cell to the second cell, the terminal device does not need to enter a connected state, but may remain in a non-connected state.

[0132] In the above scenarios, it can be seen that in scenarios 1, 2, and 4, when the terminal device performs handover or reselection from the first cell to the second cell, the terminal device needs to enter a connected state. From the existing deactivation procedure, it can be seen that the network device may release the RRC connection of the terminal device corresponding to the deactivated service. If the service TMGI1 in the above scenario is the deactivated service, after the terminal device performs handover or reselection to the second cell and enters a connected state, the terminal device may be released to a disconnected state again. As a result, the terminal device performs handover or reselection to the target serving cell, which generates unnecessary access and wastes resources.

[0133] Based on the technical problems found in the above scenarios 1, 2, and 4, an embodiment of the present application provides a communication method for solving a problem of how to avoid unnecessary access when a terminal device receiving a multicast service in a disconnected state performs handover or reselection from a source serving cell to a target serving cell.

[0134] In the above scenarios 1, 2, and 4, when a terminal device in an RRC disconnected state performs handover or reselection from a first cell to a second cell, an embodiment of the present application provides a diagram of a communication method shown in Figure 6. The method may include the following steps:

[0135] S610: The terminal device receives first information, where the first information is related to a status of a first multicast service, and / or the first information is related to configuration information of the first multicast service in a second cell.

[0136] Optionally, the state of the first multicast service comprises an active state or an inactive state.

[0137] Optionally, when the first information relates to configuration information of the first multicast service in the second cell, the first cell and the second cell are neighboring cells, the second cell is a cell in an RNA or a tracking area (TA), or the second cell is a cell in a specific area, the first information may be an information list of cells, or the first information may be a cell information list including relevant information of the second cell.

[0138] It should be understood that the configuration information of the first multicast service in this application may be multicast service configuration information, radio bearer configuration information, or PTM configuration information, which is not limited in this application.

[0139] The first information may alternatively be from the first cell and / or a network equipment serving the first cell (referred to herein as the first network equipment).

[0140] It should be understood that the first network equipment is a network equipment that serves the first cell.

[0141] Optionally, the first information is conveyed in at least one of a paging message, a system information block (SIB), and MCCH information.

[0142] Optionally, the first information may alternatively be conveyed in an RRC release message or an RRC reconfiguration message, which is not limited in this application. The RRC release message is used to release the terminal device to an unconnected state.

[0143] S620: The terminal device determines, based on the first information, whether to send first request information to the second cell, where the first request information is used to establish or resume an RRC connection.

[0144] Specifically, after the terminal device receives the first information, the terminal device determines whether to transmit first request information to the second cell based on the first information.

[0145] Optionally, if the state of the first multicast service in the first information is active, the terminal device transmits first request information to the second cell, and the first request information is used by the terminal device to request establishment or resumption of an RRC connection.

[0146] Optionally, if the state of the first multicast service in the first information is inactive, the terminal device remains in a disconnected state.

[0147] Optionally, if the configuration information of the first multicast service of the first cell in the first information is different from the configuration information of the second cell, the terminal device sends first request information to the second cell.

[0148] Optionally, if the configuration information of the first multicast service in the first cell in the first information is the same as the configuration information in the second cell, the terminal device remains in a non-connected state.

[0149] Optionally, if the configuration information of the first multicast service of the first cell in the first information is the same as the configuration information of the second cell and the state of the first multicast service is active, the terminal device transmits first request information to the second cell.

[0150] Optionally, if the configuration information of the first multicast service of the first cell in the first information is the same as the configuration information of the second cell and the state of the first multicast service is in an inactive state, the terminal device remains in a non-connected state.

[0151] In addition, when the terminal device performs handover or reselection from the first cell to the second cell and continues to remain in a disconnected state, the terminal device may further receive a first paging message. The first paging message includes an identifier of the first multicast service, and the terminal device determines that the first multicast service is active or that the terminal device needs to enter a connected state. For example, the terminal device transmits first request information to the second cell based on the first paging message and enters the connected state.

[0152] According to the method shown in FIG. 6, the method may further include:

[0153] The terminal device receives the second information, and the second information is used to determine that the second cell does not provide the first multicast service to the terminal device in an unconnected state.

[0154] It should be understood that the second cell may further directly indicate to the terminal device that the second cell does not provide the first multicast service to the terminal device in the disconnected state, and the terminal device may further decide whether to enter the connected state based on the second information.

[0155] It should be understood that the terminal device may receive the second information before receiving the first information, or may receive the second information after receiving the first information, which is not limited in the present application.

[0156] Optionally, when the second information includes MCCH configuration information of the second cell, the terminal device obtains third information based on the MCCH configuration information, where the third information includes MCCH information of the second cell and the MCCH information does not include an identifier of the first multicast service, which is used by the terminal device to determine that the second cell does not provide the first multicast service to the terminal device in a disconnected state.

[0157] Optionally, when the second information includes MCCH configuration information of the second cell, if the terminal device fails to obtain the third information based on the MCCH configuration information, it indicates that the MCCH information of the second cell is null or there is no MCCH information.

[0158] The terminal device determines that the second cell does not support multicast services in a disconnected state.

[0159] Note that the MCCH / MCCH configuration information in this application is used for multicast transmission.

[0160] It should be understood that the first information may further include PDCP synchronization information of the first cell and / or PDCP synchronization information of the second cell, and the synchronization information includes whether the PDCP of the first cell is synchronized or not synchronized and / or whether the PDCP of the second cell is synchronized or not synchronized.

[0161] In this application, PDCP synchronization means that a network device (e.g., a base station) corresponding to the first or second cell generates a PDCP number using a number in a data packet transmitted from the core network. PDCP asynchronous means that a network device (e.g., a base station) corresponding to the first or second cell does not generate a PDCP number using a number in a data packet transmitted from the core network. The number in a data packet transmitted from the core network may be an MBS QFI SN.

[0162] If the first information includes that the PDCP of the first cell is not synchronized and / or that the PDCP of the second cell is not synchronized, the terminal device re-establishes a PDCP entity, resets / initializes PDCP variables, and / or the terminal device discards buffered PDCP data packets, or delivers buffered PDCP data packets to a higher layer, and / or the terminal device sends first request information to the first cell or the second cell to establish or resume an RRC connection. After entering the connected state, the terminal device receives a PDCP configuration in the first cell and / or the second cell.

[0163] Furthermore, when the terminal device performs handover or reselection from the first cell to the second cell, the second cell may not use the PDCP synchronization mechanism. When the terminal device performs handover or reselection to the second cell, it is further necessary to determine whether the processing mechanism of the PDCP layer is continuous. The first information further indicates PDCP synchronization information of the second cell and is further used by the terminal device to determine the processing of the PDCP layer or PDCP entity.

[0164] In the method shown in FIG. 6, when a terminal device in an RRC unconnected state performs handover or reselection from a first cell to a second cell, the terminal device receives first information and determines, based on the first information, whether to transmit first request information to the second cell to request entry into a connected state. The first information relates to the state of a first multicast service and / or the configuration of the second cell, and the terminal device further determines whether to remain in the unconnected state or to transmit the first request information to the second cell. This prevents the terminal device from directly transmitting the first request information to the second cell to request execution of handover or retransmission from the first cell to the second cell and establishment or resumption of an RRC connected state. In the present application, the terminal device needs to determine whether to transmit the first request information to the second cell based on the received first information and the first condition. This avoids the problem of the terminal device being quickly released to the unconnected state after initiating a request to the second cell and entering a connected state, thereby reducing resource consumption.

[0165] In the following, a specific method for determining whether to transmit first request information to the second cell based on the first information in the above-mentioned scenarios 1 and 2 when the first information is related to the status of the first multicast service will be described in detail. Figure 7 is a diagram of another communication method according to an embodiment of the present application. The method includes the following steps:

[0166] S710: The terminal device receives first information from a first cell.

[0167] In response to this, the first cell transmits the first information to the terminal device.

[0168] Specifically, when a terminal device in an unconnected state performs handover or reselection from a first cell to a second cell, the terminal device receives first information from the first cell, and the first information indicates a state of a first multicast service, where the first multicast service is a multicast service received by the terminal device in an unconnected state in the first cell, and the state of the first multicast service includes an active state or an inactive state.

[0169] The first cell is the source serving cell of the terminal device, and the second cell is the target serving cell to which the terminal device performs handover or reselection.

[0170] Optionally, the terminal device obtains the first information using a paging message, a system information block (IB) and an MCCH message.

[0171] Optionally, the terminal device obtains the first information using RRC release information or by entering a connected state.

[0172] The terminal device determines whether to transmit the first request information to the second cell based on the first information. The specific determination criterion is that the state of the first multicast service is active or inactive. The details are as follows:

[0173] Case 1: The state of the first multicast service in the first information is active.

[0174] According to the method shown in FIG. 7, the method further includes the following steps:

[0175] S720: The terminal device transmits first request information to the second cell based on the first information.

[0176] In response to this, the second cell receives the first request information from the terminal device.

[0177] The state of the first multicast service is active, and the terminal device transmits first request information to the second cell.

[0178] Specifically, the terminal device receives a first multicast service from a first cell, and the state of the first multicast service may be an active state or an inactive state. When the state of the first multicast service is an active state, the terminal device performs handover or reselection from the first cell to a second cell, and the terminal device transmits first request information to the second cell.

[0179] For example, the terminal device initiates an RRC resumption / establishment procedure to enter the connected state. Based on the above scenarios 1 and 2, the second cell provides the first multicast service only in the connected state, or the second cell does not provide the first multicast service and needs to trigger the establishment of the service after entering the connected state.

[0180] In the above-mentioned scenarios 1 and 2, if the terminal device does not determine that the second cell provides a corresponding multicast service and / or the same configuration, the terminal device directly determines whether to send the first request information to the second cell to establish / resume an RRC connection based on the status of the first multicast service.

[0181] Case 2: The state of the first multicast service in the first information is inactive.

[0182] According to the method shown in FIG. 7, the method further includes the following steps:

[0183] S720': The terminal device determines to remain in a non-connected state based on the first information.

[0184] Specifically, the terminal device receives first information from the first cell, and the first information indicates that the state of the first multicast service is an active state or an inactive state. If the state of the first multicast service is an inactive state, the terminal device performs handover or reselection from the first cell to the second cell, and the terminal device continues to remain in a disconnected state.

[0185] For example, the terminal device does not initiate an RRC resumption / establishment procedure to avoid being released after entering a connected state. The terminal device remains in a disconnected state and waits for a subsequent activation procedure to initiate a paging request. According to the method shown in FIG. 7, the method further includes the following steps:

[0186] S730': The terminal device receives the first paging message.

[0187] When the terminal device receives the first paging message, the terminal device determines whether to enter a connected state based on the first paging message. If the first paging message is a paging for service activation, the terminal device does not send first request information to the second cell. If the first paging message includes an identifier of the first multicast service, the terminal device determines that the first multicast service is active or that the terminal device needs to enter a connected state. For example, the terminal device sends first request information to the second cell based on the first paging message and enters a connected state.

[0188] Specifically, after the subsequent paging reaches the terminal device, the terminal device does not determine whether the second cell and the first cell have the same configuration information of the first multicast service, so the terminal device needs to initiate an RRC resumption / establishment procedure to enter a connected state and obtain the configuration information of the first multicast service of the second cell. If the terminal device determines that the configuration information of the first multicast service of the second cell is the same as the configuration information of the first multicast service of the first cell, the terminal device performs the method shown in Figure 8. For details, please refer to the description of Figure 8. The details will not be described again here.

[0189] If the terminal device is in a disconnected state in the first cell, the received services may include multiple services. If the multiple services include an active service, the terminal device needs to send first request information to the second cell to resume or establish an RRC connection. According to the method shown in FIG. 7, the method further includes the following steps:

[0190] S740': The terminal device transmits first request information to the second cell.

[0191] In response to this, the second cell receives the first request information from the terminal device.

[0192] The first request information is used to establish or resume an RRC connection.

[0193] In the method shown in FIG. 7, when a terminal device in an unconnected state performs handover or reselection from a first cell to a second cell, the terminal device does not need to determine whether to enter a connected state based on whether the second cell and the first cell belong to the same RAN, and / or whether the second cell and the first cell support the same service, and / or whether the configuration information of the service corresponding to the second cell and the first cell is the same. Instead, the terminal device directly determines whether to send first request information to the second cell based on the state of the first multicast service in the first information. If the state of the first multicast service is an active state, the terminal device sends the first request information to the second cell. If the state of the first multicast service is an inactive state, the terminal device remains in the unconnected state, waits to be awakened by paging, and then sends the first request information to the second cell. According to the method shown in FIG. 7, the problem of the terminal device determining that it should be quickly released to a disconnected state after entering a connected state in the second cell based on whether the first cell and the second cell belong to the same RAN, and / or whether the supported services are the same, and / or whether the configuration information of the corresponding services is the same is avoided, thereby reducing resource consumption.

[0194] For the above Scenario 4, Figure 8 is a diagram of another communication method according to an embodiment of the present application. As shown in Figure 8, the method may include the following steps:

[0195] S810: The terminal device receives the first information.

[0196] The first information is from a first cell and includes a state of a first multicast service.

[0197] Step S810 is the same as step S710 shown in Fig. 7. For details, please refer to the description of S710. The details will not be described again here.

[0198] The terminal device may further receive second information from the second cell, the second information indicating that the second cell does not provide the first multicast service to the terminal device in an unconnected state.

[0199] The second information may directly indicate that the second cell does not provide the first multicast service to terminal devices in a disconnected state, or the second information may indirectly indicate that the second cell does not provide the first multicast service to terminal devices in a disconnected state (i.e., the second cell supports multicast services in a disconnected state, but the multicast services supported in the disconnected state do not include the first multicast service). For example, the second information does not include information related to an MCCH (e.g., MCCH configuration information). Specifically, the second information indicates that the second cell does not provide the first multicast service to terminal devices in a disconnected state. The second information includes MCCH configuration information of the second cell. The first cell obtains the third information based on the MCCH configuration information. The third information includes MCCH information of the second cell, and the MCCH information of the second cell does not include an identifier of the first multicast service. That is, the second cell does not provide the first multicast service in a disconnected state. The second information includes MCCH configuration information of the second cell. If the first cell fails to acquire the third information based on the MCCH configuration information, it is considered that the second cell does not provide the first multicast service to the terminal device in the disconnected state.

[0200] Based on the possible cases of the second information, the following will provide a detailed explanation of the cases where the second information directly indicates that the second cell does not provide the first multicast service to a terminal in a disconnected state, and the case where the second information indirectly indicates that the second cell does not provide the first multicast service in a disconnected state.

[0201] Case 1: S820: The terminal device receives second information from a second cell.

[0202] In response, the second cell transmits second information to the terminal device.

[0203] The second information indicates that the second cell does not provide the first multicast service to terminal devices in an unconnected state.

[0204] Optionally, the second information may directly indicate that the second cell does not provide the first multicast service to the terminal in a disconnected state, or the second information may indicate that the second cell does not provide the first multicast service in a disconnected state.

[0205] S830: The terminal device determines, based on the second information, that the second cell does not provide the first multicast service to the terminal device in a disconnected state.

[0206] Specifically, after receiving the second information from the second cell, the terminal device determines, based on the second information, that the second cell does not provide the first multicast service in a disconnected state. According to the method shown in FIG. 8, the method further includes the following steps:

[0207] S840: The terminal device determines whether to transmit the first request information to the second cell based on the first information.

[0208] Specifically, when the terminal device determines that the second cell does not provide the first multicast service to the disconnected terminal device, the terminal device determines, based on the first information, whether to transmit first request information to the second cell, where the first request information is used to establish or resume an RRC connection.

[0209] It should be understood that in step S840, the terminal device determines whether to send first request information to the second cell based on the first information. For details, please refer to the detailed description of Case 1 and Case 2 in Figure 7. To avoid redundancy, the details will not be described again here.

[0210] Case 2: S820': The terminal device receives second information from a second cell.

[0211] In response, the second cell transmits second information to the terminal device.

[0212] The second information indicates that the second cell does not provide the first multicast service to terminal devices in an unconnected state.

[0213] Optionally, the second information includes configuration information of the MCCH of the second cell.

[0214] S830': The terminal device transmits second request information to the second cell.

[0215] Specifically, when the terminal device receives the second information of the second cell and the second information includes the MCCH configuration information of the second cell, the terminal device transmits second request information to the second cell, which is used to acquire the MCCH information of the second cell based on the MCCH configuration information.

[0216] Optionally, if the second cell includes MCCH information, the method, ie, the method shown in FIG. 8, further includes:

[0217] S840': The terminal device receives the third information from the second cell, or the second cell transmits the third information to the terminal device.

[0218] Specifically, when the second cell receives the second request information from the terminal device, the second cell transmits the third information to the terminal device based on the second request information, where the third information includes the MCCH information of the second cell.

[0219] Optionally, if the MCCH information in the third information does not include an identifier of the first multicast service, the terminal device determines that the second cell does not provide the first multicast service to the terminal device in a disconnected state.

[0220] S850': The terminal device determines, based on the third information, that the second cell does not provide the first multicast service to the terminal device in the disconnected state.

[0221] It should be understood that the terminal device sends the second request information to the second cell, and the terminal device may not receive the third information, that is, the MCCH information of the second cell is empty or the MCCH information is not lost, that is, steps S840' and S850' are optional.

[0222] S860': The terminal device determines whether to transmit the first request information to the second cell based on the first information.

[0223] Specifically, when the terminal device determines that the second cell does not provide the first multicast service to the disconnected terminal device, the terminal device determines, based on the first information, whether to transmit first request information to the second cell, where the first request information is used to establish or resume an RRC connection.

[0224] It should be understood that in step S860', the terminal device determines whether to send first request information to the second cell based on the first information. For details, please refer to the detailed description of Case 1 and Case 2 in Figure 7. To avoid redundancy, the details will not be described again here.

[0225] 8 are not limited to being performed after step S810. Alternatively, steps S820 and S820' may be performed before step S810. This is not a limitation in the present application.

[0226] According to the method shown in FIG. 8, when a terminal device in an unconnected state performs handover or retransmission from a first cell to a second cell, the terminal device receives second information from the second cell, and the second information is used to determine that the second cell does not provide a first multicast service to the unconnected terminal device. The terminal device determines whether to transmit first request information to the second cell based on the state of the first multicast service. If the second information received by the terminal device includes MCCH configuration information of the second cell, the terminal device acquires MCCH service information of the second cell based on the MCCH configuration information. The terminal device further determines whether the second cell supports the first multicast service in an unconnected state based on the service information. If the terminal device determines that the second cell does not provide the first multicast service to the unconnected terminal device or that the second cell does not provide multicast in an unconnected state, the terminal device transmits first request information to the second cell based on the state of the first multicast service to establish or resume an RRC connection, or waits to be awakened by paging.

[0227] 9 is a schematic flowchart of another communication method according to an embodiment of the present application. The method is applicable to any of the above scenarios 1 to 5. FIG. 9 illustrates a specific method for a terminal device to determine, based on first information, whether to transmit first request information to a second cell when the first information relates to configuration information of a first multicast service in the second cell. According to the method illustrated in FIG. 9, the method includes:

[0228] S910: The first network device receives configuration information of the first multicast service in the second cell.

[0229] Correspondingly, the second cell transmits configuration information of the first multicast service in the second cell to the first network device.

[0230] The information exchange between the first network device and the second cell may occur via an Xn interface.

[0231] Specifically, the first network device determines, based on the configuration information of the first multicast service in the second cell, whether the configuration information of the first cell is the same as or different from the configuration of the second cell. The first network device determines the first information based on the configuration information of the first multicast service in the second cell, and transmits the first information to the terminal device, so that the terminal device determines whether to transmit the first request information to the second cell.

[0232] The first network device is a network device that serves the first cell, and the first cell and the second cell are neighboring cells, or the second cell is a cell within the range of the first cell, or the first cell and the second cell are cells within the same RNA.

[0233] Optionally, the configuration information of the first multicast service in the second cell may include a PTM configuration of the second cell, which may include information such as a G-RNTI, a logical channel ID (LCID), a discontinuous reception (DRX), and a physical downlink shared channel (PDSCH) configuration.

[0234] Optionally, the configuration information of the first multicast service in the second cell includes one or more of: identification information of the first multicast service (e.g., TMGI1); configuration information of the first multicast service in the second cell (the configuration information may be conveyed in information such as radio bearer configuration information, PTM configuration information, multicast service configuration information, etc.); and whether PDCP is synchronized or not synchronized.

[0235] Optionally, the configuration information of the first multicast service in the second cell may further include a PDCP SN generated by the second cell using a synchronization mechanism, or the second cell does not use a synchronization mechanism. If the PDCP of the first cell and / or the PDCP of the second cell are not synchronized, the terminal device generates a processing exception (such as a packet loss or a data packet failure) based on the existing PDCP mechanism. The first information may further inform the terminal device whether the PDCP is synchronized, so that the terminal device can determine the processing of the PDCP layer / PDCP entity.

[0236] Note that, before step S910, the first network device may send third request information to the second cell via the Xn interface, where the third request information is used to request acquisition of the configuration of the second cell. The third request information may include one or more of an identifier of the first multicast service, a second cell identifier, configuration query indication information for the first multicast service in the second cell, PDCP synchronization query indication information, etc. The second cell sends the configuration information of the first multicast service in the second cell to the first network device based on the third request information.

[0237] Optionally, the configuration information of the first multicast service in the second cell includes one or more of: identification information of the first multicast service (e.g., TMGI1), configuration information of the second cell, PTM configuration information, and whether PDCP is synchronized or not synchronized. Whether PDCP is synchronized or not synchronized may be at a service level, a cell level, or a base station level, which is not limited in the present application.

[0238] Note that, if both the serving network device of the second cell and the serving network device of the first cell are the first network device, step S910 is an optional step.

[0239] S920: The terminal device receives first information from the first network device.

[0240] In response, the first network device transmits the first information to the terminal device.

[0241] Specifically, when a terminal device in a disconnected state performs a handover or reselection from a first cell to a second cell, the terminal device receives first information from a first network device, and the first information relates to configuration information of a first multicast service in the second cell.

[0242] The terminal device determines whether to transmit the first request information to the second cell based on the first information.

[0243] Optionally, if the configuration information of the first multicast service of the first cell in the first information is different from the configuration information of the second cell, the terminal device sends first request information to the second cell.

[0244] Optionally, if the configuration information of the first multicast service in the first cell in the first information is the same as the configuration information in the second cell, the terminal device remains in a non-connected state, as detailed below.

[0245] Case 1: The configuration information of the first multicast service in the first cell in the first information is different from the configuration information of the second cell.

[0246] According to the method shown in FIG. 9, the method further includes the following steps:

[0247] S930: The terminal device transmits first request information to the second cell based on the first information.

[0248] In response to this, the second cell receives the first request information from the terminal device.

[0249] The configuration information of the first multicast service of the first cell in the first information is different from the configuration information of the second cell, and the terminal device transmits first request information to the second cell.

[0250] Case 2: The configuration information of the first multicast service in the first cell is the same as the configuration information of the second cell.

[0251] According to the method shown in FIG. 9, the method further includes the following steps:

[0252] S930': The terminal device determines to remain in a non-connected state based on the first information.

[0253] Specifically, the terminal device receives first information from a first cell, and the configuration information of the first multicast service in the first cell in the first information is the same as the configuration information in the second cell. The terminal device performs handover or reselection from the first cell to the second cell, and the terminal device continues to remain in a disconnected state.

[0254] In addition, when the first information is related to the state of the first multicast service in the second cell and the configuration information of the first multicast service, if the configuration information of the first multicast service in the first cell in the first information is the same as the configuration information in the second cell and the state of the first multicast service is inactive, the terminal device transmits the first request information to the second cell.

[0255] In addition, if the configuration information of the first multicast service of the first cell in the first information is the same as the configuration information of the second cell and the state of the first multicast service is inactive, the terminal device remains in a non-connected state.

[0256] S940': The terminal device receives the first paging message.

[0257] When the terminal device receives the first paging message, the terminal device determines whether to enter a connected state based on the first paging message. If the first paging message is a paging for service activation, the terminal device does not send first request information to the second cell. If the first paging message includes an identifier of the first multicast service, the terminal device determines that the first multicast service is active or that the terminal device needs to enter a connected state. According to the method shown in FIG. 9, the method further includes the following steps:

[0258] S950': The terminal device transmits first request information to the second cell.

[0259] In response to this, the second cell receives the first request information from the terminal device.

[0260] The first request information is used to establish or resume an RRC connection.

[0261] In the method shown in FIG. 9, when a terminal device in an RRC unconnected state performs handover or reselection from a first cell to a second cell, the terminal device receives first information determined by a first network device. The first information relates to configuration information of a first multicast service in the second cell. The terminal device further determines whether to transmit first request information to the second cell based on the first information. The method shown in FIG. 9 avoids the problem of the terminal device determining that the terminal device will be quickly released to an unconnected state after entering a connected state in the second cell based on whether the first cell and the second cell belong to the same RAN, and / or whether the supported services are the same, and / or whether the configuration information of the corresponding services is the same, thereby reducing resource consumption.

[0262] In the method shown in Fig. 9, the first information relates to configuration information of the first multicast service in the second cell. The terminal device determines, based on the first information, whether the configuration information of the first multicast service in the first cell is the same as or different from the configuration information in the second cell, and further determines whether to transmit first request information to the second cell or to remain in a disconnected state.

[0263] If the first information received by the terminal device from the first network device is neighboring cell information, the terminal device further determines whether to send the first request information to the second cell based on the neighboring cell information.

[0264] S1010: The first network device receives configuration information of a service in a second cell.

[0265] Correspondingly, the second cell transmits configuration information of the service in the second cell to the first network device.

[0266] The information exchange between the first network device and the second cell may occur via an Xn interface.

[0267] The service configuration information may include configuration information of all services in the second cell, or the service configuration information may include configuration information of the first multicast service.

[0268] S1020: The first network device sends neighboring cell information to the terminal device.

[0269] Correspondingly, the terminal device receives neighbor cell information from the first network device.

[0270] Optionally, the neighbor cell information may alternatively be conveyed in an RRC release message, which is used to release the terminal device to an unconnected state.

[0271] Wherein, the first network device sends an RRC release message to the terminal device, and the RRC release message releases the terminal device to an unconnected state. The neighbor cell information may be carried in the RRC release message sent by the first network device to the terminal device.

[0272] Specifically, after receiving the service configuration information of the second cell, the first network device determines neighboring cell information based on the service configuration information of the second cell, where the neighboring cell information includes the configuration information of all services in the second cell.

[0273] S1030: The terminal device determines to remain in a non-connected state based on the neighboring cell information.

[0274] Specifically, when the terminal device receives neighboring cell information from the first network device and the neighboring cell information includes configuration information of all services of the second cell, or when the neighboring cell information includes configuration information of the first multicast service of the second cell, the terminal device remains in a disconnected state.

[0275] If the neighboring cell information does not include related information of the second cell, the terminal device performs a handover or reselection from the first cell to the second cell, and the terminal device needs to send first request information to the second cell to enter a connected state.

[0276] S1040: The terminal device receives a first paging message.

[0277] The terminal device receives the first paging message.

[0278] When the terminal device receives the first paging message, the terminal device determines whether to enter a connected state based on the first paging message. If the first paging message includes an identifier of the first multicast service, the terminal device determines that the first multicast service is active or that the terminal device needs to enter a connected state. For example, the terminal device sends first request information to the second cell based on the first paging message and enters the connected state. According to the method shown in FIG. 10, the method further includes:

[0279] S1050: The terminal device transmits first request information to the second cell.

[0280] In response to this, the second cell receives the first request information from the terminal device.

[0281] The first request information is used to establish or resume an RRC connection.

[0282] In the method shown in Figure 10, if a terminal device receives neighboring cell information from a first network device and the neighboring cell information includes configuration information of all services of a second cell, the terminal device determines to remain in a non-connected state based on the neighboring cell information.

[0283] Note that the first information transmitted by the first network device to the terminal device shown in FIG. 10 is neighboring cell information, and the neighboring cell information is not limited to neighboring cells within the cell range. In this application, the neighboring cell information includes related information of all cells that the first network device can acquire, and the related information may be referred to as neighboring cell information. Therefore, the neighboring cell information is simply a name of information and is not limited to related information of neighboring cells of the first cell. As long as the first network device can acquire related information of a cell, the related information of the cell can be referred to as neighboring cell information. This is not a limitation in this application.

[0284] According to the above method, after the terminal device receives the configuration information of all services of the second cell or the configuration information of the first multicast service, the terminal device remains in a disconnected state. After the terminal device receives a first paging message including an identifier of the first multicast service, the terminal device transmits first request information to the second cell, and the first request information is used to establish or resume an RRC connection.

[0285] When the terminal device determines whether to enter a connected state based on the information received from the first network device, the PDCP windowing mechanism of the first cell and / or the PDCP windowing mechanism of the second cell may also be exceptional. Therefore, the first network device may further inform the terminal device whether the PDCP of the first cell and / or the PDCP of the second cell are synchronized, so that the terminal device can determine the processing of the PDCP layer / PDCP entity. Figure 11 is a diagram of another communication method according to an embodiment of the present application.

[0286] As shown in FIG. 11, the method includes the following steps:

[0287] S1110: The first network device sends third request information to the second cell.

[0288] Correspondingly, the second cell receives third request information from the first network device.

[0289] Specifically, the third request information is used to acquire the PDCP synchronization information of the second cell.

[0290] Optionally, the third request information includes one or more of an identifier of the first multicast service, a second cell identifier, PTM configuration query indication information, PDCP synchronization query indication information, and the like.

[0291] S1120: The first network device receives PDCP synchronization information from the second cell.

[0292] Correspondingly, the second cell transmits the PDCP synchronization information of the second cell to the first network device.

[0293] Specifically, after the first network device sends the third request information to the second cell, the second cell sends the PDCP synchronization information of the second cell to the first network device.

[0294] Optionally, the PDCP synchronization information includes whether the PDCP of the second cell is synchronized or not synchronized.

[0295] Whether PDCP is synchronized or not may be at the service level, cell level, or base station level, which is not limited in this application.

[0296] It should be noted that the information exchange (for example, the third request information) between the first network device and the second cell may be realized via the Xn interface.

[0297] S1130: The first network device determines first information based on configuration information of the first multicast service in the second cell.

[0298] Specifically, after receiving the configuration information of the first multicast service of the second cell, the first network device determines the first information based on the configuration information of the first multicast service of the second cell. The first information may be referred to as a neighbor cell information list or other information, which is not limited in the present application.

[0299] Optionally, the first information includes one or more of: configuration information of the first multicast service in the second cell, service information of the second cell, and whether PDCP of the second cell is synchronized.

[0300] The first information may further include related information and common information for each service. A specific expression format is not limited in this application.

[0301] S1140: The first network device sends the first information to the terminal device.

[0302] In response, the terminal device receives the first information from the first network device.

[0303] In the process of transmitting the first information to the terminal device, the first network device may transmit the first information to the terminal device through an RRC release message, an MCCH message, or an SIB message, which is not limited in the present application.

[0304] S1150: The terminal device determines a PDCP layer processing operation based on the first information.

[0305] Optionally, the terminal device determines whether to initialize PDCP based on whether the PDCP of the second cell is synchronized in the first information. If the PDCP of the second cell is not synchronized, the terminal device may reset a PDCP entity or PDCP variables, and / or clear buffered data packets or deliver the buffered data packets to a higher layer, and / or the terminal device may send first request information to the second cell, which is used to establish or resume an RRC connected state. After entering the connected state, the terminal device receives a PDCP configuration in the second cell.

[0306] In the method shown in FIG. 11, if the network device of the second cell and the network device of the first cell are the same network device, steps S1130 to S1150 are directly executed.

[0307] Further, it should be noted that if the PDCP of the first cell is not synchronized, the aforementioned steps S1130 to S1150 may be performed. If the PDCP of the first cell or the PDCP of the second cell is not synchronized, the terminal device may reset a PDCP entity or PDCP variables, and / or clear buffered data packets, or deliver the buffered data packets to an upper layer, and / or the terminal device may send first request information to the first cell and / or the second cell, where the first request information is used to establish or resume an RRC connected state. After entering the connected state, the terminal device receives a PDCP configuration in the first cell and / or the second cell.

[0308] The method shown in Figure 11 provides a method for a terminal device to process a PDCP layer / PDCP entity. The terminal device may further determine a processing operation of the PDCP layer based on the PDCP synchronization information of the second cell in the first information.

[0309] Figure 12 shows a communication architecture to which an embodiment of the present application can be applied. Figure 12 shows a CP-UP split architecture in a network device. In this method, the method shown in Figure 12 will be described in detail using an example in which the network device is a base station (e.g., a gNB). The gNB may include a gNB-CU-CP, multiple gNB-CU-UPs, and multiple gNB-DUs. The gNB-CU-CP is connected to the gNB-DU via an F1-C interface, the gNB-CU-UPs are connected to the gNB-DU via an F1-U interface, and the gNB-CU-UPs are connected to the gNB-CU-CP via an E1 interface.

[0310] Specifically, as shown in Figure 12, one gNB-DU is connected to only one gNB-CU-CP, and one gNB-CU-UP is connected to only one gNB-CU-CP. When using the CP-UP split architecture on the base station side, if an MRB exchange is required, the gNB-CU-CP of the base station needs to obtain the MRB progress from the gNB-CU-UP.

[0311] Unlike unicast services, in an environment where a terminal device performs a handover from a source base station to a target base station, it is not possible to determine the last data packet sent from the MRB on the source base station to the terminal device. In the case of MRB, the establishment of F1-U is not necessarily based on the terminal device level; F1-U is likely to be established at the distributed unit (DU) level or cell level. Therefore, the problem to be solved is how the gNB-CU-CP queries the progress of the terminal device's gNB-CU-UP.

[0312] From the perspective of the target gNB, the target gNB needs to provide the MRB with the PDCP SN information of the oldest data packet available to the target NG-RAN node. Therefore, the target gNB-CU-UP only needs to provide the source gNB-CU-UP with the SN of the oldest data packet available on the target gNB-CU-UP side. The SN of the oldest data packet contains information about each MRB, but is not specific information about the terminal device. Therefore, the source base station's MRB information can be directly queried.

[0313] However, from the perspective of the source gNB-CU-CP, some terminal devices need to obtain MRB progress information. The MRB progress information includes the PDCP SN information of the last data packet already delivered to the terminal device for the MRB. From the perspective of the target base station gNB-CU-U, some terminal devices transmit data packets via DU / cell-level F1-U tunnels (the data packet transmission progress represents the progress of multiple terminal devices), while other terminal devices transmit data packets via terminal-level F1-U tunnels. Therefore, the MRB progress information of the source gNB is terminal-device-specific information. Therefore, how to query the MRB progress information is a technical issue to be resolved.

[0314] Regarding the above technical problem, Fig. 13 is a diagram of another communication method according to an embodiment of the present application. Hereinafter, the solution provided in the present application to the above technical problem will be described in detail with reference to the method of Fig. 13.

[0315] The method shown in FIG. 13 includes the following steps.

[0316] S1310: The source gNB-CU-CP sends third indication information to the source gNB-CU-UP.

[0317] Correspondingly, the source gNB-CU-UP receives third indication information from the source gNB-CU-CP.

[0318] The third indication information is used to determine the MRB progress information corresponding to the terminal device.

[0319] Optionally, the third indication information includes an MBS multicast F1-U context descriptor information element.

[0320] Optionally, the third indication information is included in an MC context modification request message, which specifically can include one or more of a gNB-CU-CP MBS E1AP ID, a gNB-CU-UP MBS E1AP ID, multicast bearer context modification information, and an MRB list.

[0321] For example, to obtain MRB progress information of a terminal device, the source gNB-CU-CP needs to provide the following information to the source gNB-CU-UP: 1. When a data packet transmitted by a source gNB-CU-CP to a terminal device is transmitted via a DU-level F1-U shared tunnel, the source gNB-CU-CP must provide information about the DU-level F1-U shared tunnel. The information about the shared tunnel may be explicit or implicit. For example, the branch of selection may directly indicate information about the DU-level F1-U shared tunnel, may be a DU identifier ID, or may be a source gNB-CU-CP MBS E1AP ID, a source gNB-CU-UP MBS E1AP ID, etc. 2. When the data packet sent by the source gNB-CU-CP to the terminal device is transmitted through a cell-level F1-U shared tunnel, the source gNB-CU-CP needs to provide cell information, which may be, for example, CGI or CGI+DU-ID. 3. When the data packet sent by the source gNB-CU-CP to the terminal device is transmitted through a terminal device-level F1 tunnel, the source gNB-CU-CP needs to provide terminal device information, which may be, for example, C-RNTI+DU ID or gNB-CU UE F1AP ID+gNB-DU UE F1AP ID.

[0322] It should be understood that regardless of the type of tunnel, the tunnel may be represented using the MBS Multicast F1-U Context Descriptor. Similarly, it can be understood that this field is third indication information.

[0323] Furthermore, it should be understood that an identifier is introduced each time an F1 tunnel is established. The identifier may be used to identify tunnel information, e.g., F1 Tunnel 1 or Tunnel 2. During querying, the categories may not be differentiated and the relevant identifying information may be conveyed directly to the query.

[0324] S1320: The source gNB-CU-UP sends progress response information to the source gNB-CU-CP.

[0325] Correspondingly, the source gNB-CU-CP receives progress response information from the source gNB-CU-UP.

[0326] The progress response information indicates the MRB progress information of each terminal device. Alternatively, the progress response information may be a different information name. This is not limited in the present application.

[0327] Optionally, the progress response information is included in an MC context modification response message, and the MC context modification response message further includes at least one of a gNB-CU-CP MBS E1AP ID, a gNB-CU-UP MBS E1AP ID, multicast bearer context modification response information, and an MRB list.

[0328] In the method shown in Figure 13, the source gNB-CU-CP sends third indication information to the source gNB-CU-UP, where the third indication information is used to determine MRB progress information corresponding to the terminal device. The source gNB-CU-UP sends progress response information to the source gNB-CU-CP, where the progress response information indicates the MRB progress information of each terminal device. The source gNB-CU-CP can determine the progress of the MRB corresponding to each terminal device using the method shown in Figure 13.

[0329] Note that the specific progress corresponding to the MRB in FIG. 13 may alternatively be the slowest transmission progress in the F1 transmission tunnels of different levels corresponding to the MRB. For example, the progress fed back in the DU-level tunnel is No. 5, and the progress fed back in the UE-level tunnel is No. 6. Because the source gNB-CU-UP does not know which tunnel data the UE has received, the source gNB-CU-UP selects the slowest progress and sends it to the source gNB-CU-CP. In this way, this conservative MRB process is used to forward data between the source base station and the target base station, and no data packets are missed. The data packets to be transmitted from the target base station to the UE are determined based on the PDCP status report reported by the UE at the target base station. Some data packets may still be transmitted, but at least there are no transmission omissions or errors.

[0330] The communication method provided in the embodiment of the present application has been described in detail above with reference to Figures 6 to 13. Hereinafter, the communication device provided in the embodiment of the present application will be described in detail with reference to Figures 14 and 15.

[0331] The following describes in detail the communication device provided in the embodiment of the present application with reference to Figures 14 and 15. It should be understood that the description of the device embodiment corresponds to the description of the method embodiment. Therefore, for the content not described in detail, please refer to the above-mentioned method embodiment. For the sake of brevity, some of the content will not be described again.

[0332] In the embodiments of the present application, the functional modules of the transmitting device or the receiving device may be obtained through division based on the above-mentioned example method. For example, each functional module may be obtained through division based on each function, or two or more functions may be integrated into one processing module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. It should be noted that in the embodiments of the present application, the module division is an example and is merely a logical function division. In actual implementation, other division methods may be used. An example in which each functional module is obtained through division based on each corresponding function is used below for explanation.

[0333] 14 is a block diagram of an example of an information transmission device 1400 according to the present application. Any device such as the terminal device and network device in any of the methods of FIGS. 6 to 13 can be realized by the communication device shown in FIG.

[0334] It should be noted that the information transmission device 1400 may be a physical device, a component of a physical device (for example, an integrated circuit or chip), or a functional module within a physical device.

[0335] As shown in FIG. 14, the communications device 1400 includes one or more processors 1410. Optionally, the processor 1410 may invoke an interface to implement the receiving and transmitting functions. The interface may be a logical interface or a physical interface, without being limited thereto. For example, the interface may be a transceiver circuit, an input / output interface, or an interface circuit. The transceiver circuit, the input / output interface, or the interface circuit configured to implement the receiving and transmitting functions may be separate or integrated together. The transceiver circuit or the interface circuit may be configured to read or write code / data, or the transceiver circuit or the interface circuit may be configured to transmit or forward signals.

[0336] Optionally, the interface can be implemented using a transceiver. Optionally, the information transmission device 1400 may further include a transceiver 1430. The transceiver 1430 may also be referred to as a transceiver unit, transceiver machine, transceiver circuit, etc., and is configured to implement receiving and transmitting functions.

[0337] Optionally, the communication device 1400 may further include a memory 1420. The specific deployment location of the memory 1420 is not specifically limited in this embodiment of the present application. The memory may be integrated with the processor or may be independent of the processor. If the device 1400 does not include a memory, it is sufficient that the device 1400 has a processing function, and the memory may be located elsewhere (e.g., a cloud system).

[0338] The processor 1410, memory 1420, and transceiver 1430 communicate with each other through interconnection paths to transfer control and / or data signals.

[0339] Although not shown, it should be understood that the device 1400 may further include other devices, such as an input device, an output device, or a battery.

[0340] Optionally, in some embodiments, the memory 1420 can store executable instructions for performing the methods in the embodiments of the present application. The processor 1410 can execute the instructions stored in the memory 1420, in combination with other hardware (e.g., the transceiver 1430), to achieve the steps performed in the following methods. For specific operation processes and beneficial effects, please refer to the descriptions in the preceding method embodiments.

[0341] The methods disclosed in the embodiments of the present application may be applied to or performed by the processor 1410. The processor 1410 may be an integrated circuit chip and have signal processing capabilities. In the implementation process, the steps of the methods may be implemented using hardware integrated logic circuits in the processor or using instructions in the form of software. The processor may be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), or another programmable logic element, a discrete gate or transistor logic element, or a discrete hardware component. The processing device may implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of the present application. The general-purpose processor may be a microprocessor, or the processor may be any conventional processor, etc. The steps of the methods disclosed with reference to the embodiments of the present application may be directly executed or achieved using a hardware decoding processor, or may be executed or achieved using a combination of hardware and software modules in the decoding processor. The software module may be located in a conventional storage medium such as a random access memory (RAM), a flash memory, a read-only memory (ROM), a programmable read-only memory, an electrically erasable programmable memory, or a register. The storage medium may be located in the memory, and the processor reads the instructions in the memory and performs the steps of the aforementioned method in combination with the processor hardware.

[0342] It should be appreciated that memory 1420 may be volatile, nonvolatile, or both. Nonvolatile memory may be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. Volatile memory may be random access memory (RAM), which may act as an external cache. By way of example, and not limitation, many types of RAM may be used, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct Rambus random access memory (DR RAM). It should be noted that memory in the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0343] 15 is a block diagram of a communication device 1500 according to the present application. The device 1500 includes a transceiver unit 1520, which may be configured to perform corresponding communication functions. The transceiver unit 1520 may also be referred to as a communication interface or a communication unit.

[0344] Optionally, the device 1500 further includes a processing unit 1510, which may be configured to perform data processing.

[0345] Optionally, the specific form of the device 1500 configured to perform information transmission may be a general-purpose computer device or a chip within a general-purpose computer device, which is not limited to this embodiment of the present application. As shown in FIG. 15, the device includes a processing unit 1510 and a transceiver unit 1520.

[0346] Specifically, device 1500 may be any device in the present application and may implement a function that can be implemented by a device, and device 1500 may be a physical device, a component of a physical device (e.g., an integrated circuit or chip), or a functional module within a physical device.

[0347] In a possible design, the device 1500 may be a terminal device (e.g., a terminal device) in the aforementioned method embodiments, or may be a chip configured to implement the functions of a terminal device (e.g., a terminal device) in the aforementioned method embodiments.

[0348] Optionally, the device 1500 further includes a storage unit. The storage unit may be configured to store instructions and / or data. The processing unit 1510 may read the instructions and / or data in the storage unit to cause the device to perform different terminal device operations in the aforementioned method embodiments, such as the operations of a control network element or a terminal device.

[0349] The device 1500 may be configured to perform the operations performed by a control network element or terminal device in the aforementioned method embodiments. In this case, the device 1500 may be a control network element or terminal device, or a component of a control network element or terminal device. The transceiver unit 1520 is configured to perform the operations related to transmission and reception of the control network element or terminal device in the aforementioned method embodiments, and the processing unit 1510 is configured to perform the operations related to processing of the control network element or terminal device in the aforementioned method embodiments.

[0350] It should be noted that device 1500 may be configured to perform the operations performed by the controlling network element or network device in the method embodiments described above. In this case, transceiver unit 1520 in device 1500 may be realized via a communication interface (e.g., a transceiver or an input / output interface) and may, for example, correspond to communication interface 1430 shown in Figure 14. Processing unit 1510 in device 1500 may be implemented using at least one processor and may, for example, correspond to processor 1410 shown in Figure 14.

[0351] Optionally, the device 1500 may further include a storage unit. The storage unit may be configured to store instructions or data. The processing unit can access the instructions or data stored in the storage unit and perform corresponding operations.

[0352] It should be understood that in the above method embodiments, the specific processes by which the units perform the above corresponding steps have been described in detail, and for the sake of brevity, the details will not be described again here.

[0353] It should be understood that in the above method embodiments, the specific processes by which the units perform the above corresponding steps have been described in detail, and for the sake of brevity, the details will not be described again here.

[0354] Furthermore, in this application, the communication device 1500 is presented in the form of a functional module. A "module" herein may be an application-specific integrated circuit (ASIC), a circuit, a processor and memory executing one or more software or firmware programs, an integrated logic circuit, and / or another component capable of providing the aforementioned functionality. In a simple embodiment, those skilled in the art will understand that the device 1500 may be in the form shown in FIG. 15. The processing unit 1510 may be implemented using the processor 1410 shown in FIG. 14. Optionally, if the computing device shown in FIG. 14 includes memory 1420, the processing unit 1510 may be implemented using the processor 1410 and the memory 1420. The transceiver unit 1520 may be implemented using the transceiver 1430 shown in FIG. 14. The transceiver 1430 includes receiving and transmitting functions. Specifically, the processor is implemented by executing a computer program stored in memory. Optionally, if device 1500 is a chip, the functionality and / or implementation processes of transceiver unit 1520 may alternatively be realized via pins, circuitry, etc. Optionally, the memory may be a storage unit within the chip, such as a register or cache. Alternatively, the storage unit may be a storage unit within the device but located outside the chip, such as memory 1420 shown in FIG. 14, or may be a storage unit located in another system or device and not within the computing device.

[0355] Various aspects or features of the present application may be implemented as a method, apparatus, or article of manufacture using standard programming and / or engineering techniques. For example, computer-readable media may include, but are not limited to, magnetic storage components (e.g., hard disks, floppy disks, or magnetic tapes), optical disks (e.g., compact discs (CDs) or digital versatile discs (DVDs)), smart cards, and flash memory components (e.g., erasable programmable read-only memory (EPROM) cards, sticks, or key drives). Additionally, various storage media described herein may represent one or more devices and / or other machine-readable media configured to store information. The term "machine-readable medium" may include, but is not limited to, various other media capable of storing, containing, and / or transmitting instructions and / or data.

[0356] According to the method provided in the embodiment of the present application, the present application further provides a computer program product, which includes a computer program or an instruction set, which, when executed on a computer, enables the computer to perform the method according to any one of the embodiments of Figures 5 to 8.

[0357] According to the method provided in the embodiment of the present application, the present application further provides a computer-readable storage medium. The computer-readable medium stores a program or an instruction set. When the program or the instruction set is executed on a computer, the computer is enabled to execute the method according to any one of the embodiments shown in Figures 5 to 8.

[0358] According to the method provided in the embodiment of the present application, the present application further provides a communication system, which includes the above-mentioned device or apparatus.

[0359] As used herein, terms such as "component," "module," and "system" refer to computer-related entities, hardware, firmware, a combination of hardware and software, software, or software in execution. For example, a component may be, but is not limited to, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and / or a computer. As illustrated using the figures, both a computing device and an application running on a computing device may be a component. One or more components may reside within a process and / or thread of execution, and a component may be located on one computer and / or distributed between two or more computers. Furthermore, these components may execute from various computer-readable media that store various data structures. Components may communicate using local and / or remote processes, according to signals comprising one or more data packets (e.g., data from two components interacting with another component, interacting with another system using such signals, within a local system, within a distributed system, and / or across a network such as the Internet).

[0360] It should also be understood that the term "and / or" in this specification simply describes an association relationship that describes associated objects, and indicates that three relationships may exist. For example, A and / or B may represent the following three cases: only A exists, both A and B exist, and only B exists. Furthermore, the character " / " in this specification generally indicates an "or" relationship between associated objects.

[0361] It should also be understood that the numbers "first," "second," and the like are introduced in the embodiments of this specification only to distinguish between different objects, for example, to distinguish between different "information," "devices," or "units." The understanding of a specific object and the correspondence between different objects should be determined based on the function and internal logic of the specific object, and should not constitute any limitation on the implementation process of the embodiments of the present specification.

[0362] In combination with the examples described in the embodiments disclosed herein, those skilled in the art may recognize that the units and algorithms can be implemented by electronic hardware or a combination of computer software and electronic hardware. Whether a function is performed by hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art may use different methods to implement the described functions for each specific application, but the implementation should not be considered to go beyond the scope of the present application.

[0363] For the purpose of convenience and concise description, the detailed operation processes of the aforementioned systems, devices and units can be clearly understood by those skilled in the art by referring to the corresponding processes in the aforementioned method embodiments, and the details will not be described herein.

[0364] In some embodiments provided herein, it should be understood that the disclosed systems, devices, and methods may be implemented in other ways. For example, the described device embodiments are merely examples. For example, the division into units is merely a logical function division, and other divisions may occur in actual implementation. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not implemented. Furthermore, the shown or discussed mutual couplings or direct couplings or communication connections may be implemented through some interfaces. Indirect couplings or communication connections between devices or units may be implemented electronically, mechanically, or in other forms.

[0365] The units described as separate parts may or may not be physically separated. The parts shown as units may or may not be physical units, and may be located in one place or distributed among multiple network units. Some or all of the units may be selected based on actual requirements to achieve the purpose of the solution of the embodiment.

[0366] Furthermore, the functional units in the embodiments of the present application may be integrated into one processing unit, each of the units may exist physically independently, or two or more units may be integrated into one unit.

[0367] When a function is implemented in the form of a software functional unit and sold or used as an independent product, the function may be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or a portion contributing to the prior art, or all or a portion of the technical solution may be implemented in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for instructing a computer device (which may be a personal computer, a server, a network device, etc.) to perform all or a portion of the steps of the method described in the embodiments of the present application. The aforementioned storage medium includes any medium capable of storing program code, such as a USB flash drive, a removable hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0368] The above description is merely a specific implementation of the present application and is not intended to limit the scope of protection of the present application. Any modifications or replacements that are readily conceived by those skilled in the art within the technical scope disclosed in the present application should be embraced within the scope of protection of the present application. Therefore, the scope of protection of the present application should be subject to the scope of protection of the claims.

Claims

1. 1. A communication method comprising: receiving, by a terminal device, first information, wherein the first information relates to a status of a first multicast service and / or the first information relates to configuration information of the first multicast service in a second cell; determining, by the terminal device, whether to transmit first request information to the second cell based on the first information, wherein the first request information is used by the terminal device to establish or resume an RRC connection; Including, A method in which the terminal device is a terminal device that receives the first multicast service, the terminal device is a terminal device in a radio resource control (RRC) non-connected state, and the terminal device is a terminal device that performs handover or reselection from the first cell to the second cell.

2. The step of determining, by the terminal device, whether to transmit first request information to the second cell based on the first information, When the state of the first multicast service is an active state, transmitting the first request information to the second cell by the terminal device; or If the state of the first multicast service is an inactive state, remaining in the disconnected state by the terminal device; The method of claim 1 , comprising:

3. The step of determining, by the terminal device, whether to transmit first request information to the second cell based on the first information, When the configuration information of the first cell is different from the configuration information of the second cell, the terminal device transmits the first request information to the second cell; or If the configuration information of the first cell is the same as the configuration information of the second cell, remaining in the non-connected state by the terminal device; The method of claim 1 , comprising:

4. The step of determining, by the terminal device, whether to transmit first request information to the second cell based on the first information, When the configuration information of the first cell is the same as the configuration information of the second cell and the state of the first multicast service is an active state, transmitting the first request information to the second cell by the terminal device; or If the configuration information of the first cell is the same as the configuration information of the second cell and the state of the first multicast service is in an inactive state, remaining in the non-connected state by the terminal device; The method of claim 1 , comprising:

5. If the terminal device remains in the disconnected state, the method further comprises: receiving, by the terminal device, a first paging message, the first paging message including an identifier of the first multicast service; The method of any one of claims 2 to 4, further comprising:

6. The method comprises: receiving, by the terminal device, second information, the second information being used to determine that the second cell will not provide the first multicast service to the terminal device in the disconnected state; The method of any one of claims 1 to 5, further comprising:

7. When the second information includes configuration information of a multicast control channel (MCCH) of the second cell, the method further comprises: A step of acquiring third information by the terminal device based on the MCCH configuration information, wherein the third information includes MCCH information of the second cell, and the MCCH information does not include an identifier of the first multicast service; or a step of not acquiring the third information based on the configuration information of the MCCH by the terminal device; The method of claim 6 further comprising:

8. The method according to any one of claims 1 to 7, wherein the first information is conveyed in at least one of the following messages: a paging message, a system information block (SIB), and MCCH information.

9. 9. The method according to claim 1, wherein, when the first information relates to configuration information of the first multicast service in the second cell, the first information includes PDCP synchronization information of the second cell and / or PDCP synchronization information of the first cell, and the synchronization information includes whether PDCP is synchronized or not synchronized.

10. If the synchronization information includes that the PDCP of the second cell is not synchronized and / or that the PDCP of the first cell is not synchronized, the method further comprises: resetting the PDCP entity or the PDCP variables by the terminal device; and / or discarding the buffered PDCP data packets or delivering the buffered PDCP data packets to an upper layer by the terminal device; 10. The method of claim 9 further comprising:

11. 1. A communication method comprising: determining, by a first cell, first information, the first information relating to a state of a first multicast service; transmitting, by the first cell, the first information to the terminal device, the first information being used by the terminal device to determine whether to transmit first request information to a second cell, the first request information being used by the terminal device to establish or resume an RRC connection; Including, A method in which the terminal device is a terminal device that receives the first multicast service, the terminal device is a terminal device in a radio resource control (RRC) non-connected state, and the terminal device is a terminal device that performs handover or reselection from the first cell to the second cell.

12. The method of claim 11 , wherein the state of the first multicast service comprises an active state or an inactive state.

13. The method comprises: transmitting second information by the first cell to the terminal device, the second information being used to determine that the second cell will not provide the first multicast service to the terminal device in the disconnected state; The method of claim 12 further comprising:

14. The method according to any one of claims 11 to 13, wherein the first information is conveyed in at least one of a paging message, a system information block (SIB), and MCCH information.

15. 1. A communication method comprising: determining, by a second cell, second information, the second information being used to determine that the second cell will not provide the first multicast service to unconnected terminal devices; transmitting the second information to the terminal device by the second cell; Including, A method in which the terminal device is a terminal device that receives the first multicast service, the terminal device is a terminal device in a radio resource control (RRC) non-connected state, and the terminal device is a terminal device that performs handover or reselection from the first cell to the second cell.

16. When the second information includes configuration information of a multicast control channel (MCCH) of the second cell, the method further comprises: transmitting third information to the terminal device by the second cell, wherein the third information includes MCCH information of the second cell, and the MCCH information does not include an identifier of the first multicast service; 16. The method of claim 15 further comprising:

17. The method comprises: transmitting, by the second cell to a first network device, configuration information of the first multicast service in the second cell, wherein the configuration information is used to determine first information, the first information is used to determine whether the terminal device will send first request information to the second cell, and the first request information is used by the terminal device to establish or resume an RRC connection; 17. The method of claim 15 or 16, further comprising: the first cell and the second cell are neighboring cells; and the first network device is a network device that serves the first cell.

18. The method comprises: transmitting, by the second cell, PDCP synchronization information of the second cell to the first network device, the synchronization information including whether PDCP is synchronized or not synchronized; The method of any one of claims 15 to 17, further comprising:

19. 1. A communication method comprising: determining, by a first network device, first information, the first information relating to configuration information of a first multicast service in a second cell; transmitting, by the first network device, the first information to the terminal device, wherein the first information is used by the terminal device to determine whether to transmit first request information to the second cell, and the first request information is used by the terminal device to establish or resume an RRC connection; Including, A method in which the terminal device is a terminal device that receives the first multicast service, the terminal device is a terminal device in a radio resource control (RRC) non-connected state, the terminal device is a terminal device that performs handover or reselection from a first cell to the second cell, and the first network device is a network device that provides service to the first cell.

20. 20. The method of claim 19, further comprising receiving, by the first network device, configuration information for the first multicast service in the second cell, the configuration information being used to determine the first information.

21. 21. The method of claim 19 or 20, wherein the first information includes PDCP synchronization information of the second cell, and the synchronization information includes whether PDCP is synchronized or not synchronized.

22. The method according to any one of claims 19 to 21, wherein the first information is conveyed in at least one of a paging message, a system information block (SIB), and MCCH information.

23. 10. A communications device comprising at least one processor, the at least one processor coupled to at least one memory, the at least one processor configured to execute computer programs or instructions stored in the at least one memory to enable the communications device to perform a method according to any one of claims 1 to 10, to enable the communications device to perform a method according to any one of claims 11 to 14, to enable the communications device to perform a method according to any one of claims 15 to 18, or to enable the communications device to perform a method according to any one of claims 19 to 22.

24. 10. A computer readable storage medium having stored thereon instructions that, when executed on a computer, enable the computer to perform the method of any one of claims 1 to 10, or enable the computer to perform the method of any one of claims 11 to 14, or enable the computer to perform the method of any one of claims 15 to 18, or enable the computer to perform the method of any one of claims 19 to 22.

25. A chip, a memory configured to store a computer program; a processor configured to read and execute the computer program stored in the memory, wherein when the computer program is executed, the processor performs the method of any one of claims 1 to 10, or the processor is enabled to perform the method of any one of claims 11 to 14, or the processor is enabled to perform the method of any one of claims 15 to 18, or the processor is enabled to perform the method of any one of claims 19 to 22; and Including chips.

26. 10. A computer program product comprising computer program code, which, when run on a computer, enables the computer to perform the method of any one of claims 1 to 10, or enables the computer to perform the method of any one of claims 11 to 14, or enables the computer to perform the method of any one of claims 15 to 18, or enables the computer to perform the method of any one of claims 19 to 22.

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