Communication method, device and system

Abstract

The invention relates to a communication method, device and system. The network equipment determines the RNA corresponding to the first communication device, and when all cells in the RNA provide the first multicast service for the communication device in the RRC non-connection state, the data packet numbers of the first multicast service are synchronous. And the network equipment sends first information to the first communication device, wherein the first information is used for indicating the RNA. According to the embodiment of the invention, the PDCP COUNT of the cells in the UE and the RNA for the data packet of the first multicast service can be kept consistent, and the normal transmission of the first multicast service is ensured.

Description

Technical Field

[0001] This application relates to the field of communication technologies, and in particular, to a communication method, apparatus, and system. Background Art

[0002] The packet data convergence protocol (PDCP) protocol data unit (PDU) data count (COUNT) consists of a high-order hyper frame number (HFN) and a low-order PDCP sequence number (SN). Among them, the PDCP SN is added to the PDCP PDU for transmission, and the HFN is maintained by the data sender and the data receiver itself and is not added to the PDCP PDU. The PDCP PDU sent by the data sender to the data receiver contains the SN, but does not contain the complete PDCP COUNT or HFN; the data receiver calculates the HFN by itself to restore the PDCP COUNT based on the HFN and SN.

[0003] When the existing unicast data radio bearer (DRB) is established, the protocol stipulates that the HFN is not exchanged through the air interface, and both the network and the user equipment (UE) default that the HFN starts counting from 0. Based on this, it can be ensured that the HFNs of the UE and the network side are consistent. Different from the DRB of the unicast session, the multicast and broadcast service radio bearer (MRB) is shared by multiple UEs. For a multicast service, if the PDCP COUNT synchronization mechanism is adopted, the UEs that successively execute the multicast service use the same MRB, and the corresponding PDCP COUNTs should be the same. Moreover, for a multicast service, the PDCP COUNTs corresponding to the data packets received by different base stations that successively establish the MRB are also consistent. Therefore, in order to synchronize the numbers maintained by the UE, the base station, and the core network corresponding to the same MRB, when a new or re-established MRB is created, the network can indicate the initial PDCP COUNT to the UE.

[0004] For example, a UE in the radio resource control (RRC) inactive state initially receives multicast services in a certain cell. Subsequently, the UE moves to a new cell, and the UE can continue to receive the multicast services in the new cell in the RRC inactive state. If the way of generating the PDCP COUNT of data packets in the original cell and the new cell may be inconsistent (that is, the PDCP COUNT is not synchronized), it may cause the UE to be unable to correctly receive the multicast services. Summary of the Invention

[0005] Embodiments of the present application provide a communication method, device, and system for improving the success rate of a communication device receiving multicast services.

[0006] In a first aspect, a communication method is provided, which can be executed by a network device. The network device is, for example, a network equipment, or other equipment including the functions of a network equipment, or a chip system (or, chip) or other functional modules, and the chip system or functional module can implement the functions of a network equipment. The chip system or functional module is, for example, disposed in a network equipment. Optionally, the network equipment is an access network equipment. Optionally, the access network equipment is, for example, a base station, or other equipment in the access network. The method includes: determining the RNA corresponding to a first communication device, where when all cells in the RNA provide a first multicast service to a communication device in the RRC disconnected state, the packet numbers of the data packets of the first multicast service are synchronized; sending first information to the first communication device, where the first information is used to indicate the RNA.

[0007] In the embodiments of the present application, the cells in the RNA can be synchronized when providing the first multicast service in the RRC disconnected state. For example, the network device can determine the RNA of the UE accordingly. Thus, the UE can be clear that when moving between the cells in the RNA, the ways of generating the PDCP COUNT of the data packets of the first multicast service in these cells can be consistent, so that both the UE and these cells can keep the PDCP COUNT of the data packets of the first multicast service consistent, ensuring the normal transmission of the first multicast service. Based on the technical solution provided by the embodiments of the present application, the cells in the RNA can provide the first multicast service in the RRC disconnected state, and when providing the first multicast service in the RRC disconnected state, the packet numbers of the data packets of the first multicast service are synchronized, so that each cell and the UE in the RNA can have a consistent understanding of "synchronization".

[0008] In an alternative embodiment, determining the RNA corresponding to the first communication device includes: obtaining information of a first cell, where the information of the first cell is used to indicate whether the packet numbers of the first multicast service are synchronized when the first cell provides the first multicast service to a communication device in the RRC idle state; determining the RNA according to the information of the first cell. The first cell includes, for example, at least one cell, and the information of one of the cells can indicate whether the packet numbers of the first multicast service are synchronized when the cell provides the first multicast service to a communication device in the RRC idle state. Thus, the network device can determine the RNA. For example, if the information of a cell indicates that the packet numbers of the first multicast service are synchronized when the cell provides the first multicast service to a communication device in the RRC idle state, the network device can add the cell to the RNA; or, if the information of a cell indicates that the packet numbers of the first multicast service are not synchronized when the cell provides the first multicast service to a communication device in the RRC idle state, the network device may not add the cell to the RNA.

[0009] In an alternative embodiment, the information of the first cell is further used to indicate whether the packet numbers of the first multicast service are synchronized when the first cell provides the first multicast service to a communication device in the RRC connected state. The information of a cell can also indicate whether the packet numbers of the first multicast service are synchronized when the cell provides the first multicast service to a communication device in the RRC connected state. Optionally, the network device can determine the RNA based on this. For example, if the information of a cell indicates that the packet numbers of the first multicast service are synchronized when the cell provides the first multicast service to a communication device in the RRC idle state, and the information of the cell indicates that the packet numbers of the first multicast service are synchronized when the cell provides the first multicast service to a communication device in the RRC connected state, the network device can add the cell to the RNA; or, if the information of a cell indicates that the packet numbers of the first multicast service are not synchronized when the cell provides the first multicast service to a communication device in the RRC idle state, and / or the information of the cell indicates that the packet numbers of the first multicast service are not synchronized when the cell provides the first multicast service to a communication device in the RRC connected state, the network device may not add the cell to the RNA. This makes the functions of the cells in the RNA more clear.

[0010] In an alternative embodiment, when all or some of the cells within the RNA provide the first multicast service to a communication device in the RRC connected state, the packet numbers of the first multicast service are synchronized. For example, if the RNA is associated with the function that "when all or some of the cells within the RNA provide the first multicast service to a communication device in the RRC connected state, the packet numbers of the first multicast service are synchronized", then the first information does not need to be additionally indicated. Once the communication device obtains the RNA, it can be clear that when all or some of the cells within the RNA provide the first multicast service to a communication device in the RRC connected state, the packet numbers of the first multicast service are synchronized. Thereby, the indication overhead can be reduced, and the function of the RNA becomes more explicit.

[0011] In an alternative embodiment, the first information is further used to indicate that when all or some of the cells within the RNA provide the first multicast service to a communication device in the RRC connected state, the packet numbers of the first multicast service are synchronized. Optionally, if the packet numbers of the first multicast service are synchronized when some of the cells within the RNA provide the first multicast service to a communication device in the RRC connected state, the first information may further indicate these cells. For example, the first information may include the identifiers of these cells, enabling the communication device to clearly identify which cells exactly have synchronized packet numbers of the first multicast service when providing the first multicast service to a communication device in the RRC connected state.

[0012] In an alternative embodiment, the first information is used to indicate the RNA, including: the first information includes the identifiers of the cells within the RNA; or, the first information includes the identifier of the RNA. The first information may include the identifiers of the cells within the RNA, enabling the communication device to directly determine each cell; or the first information may also include the identifier of the RNA, thereby reducing the overhead of the first information. The identifier of the RNA is, for example, RNA code, or there may be other implementation manners.

[0013] In an alternative embodiment, the first information is included in an RRC release message, and the RRC release message is used to release the first communication device to the RRC idle state. For example, the network device may send the first information to the first communication device when releasing the first communication device, so that there is no need to send the first information through additional signaling, which is beneficial to saving signaling overhead. Or the network device may also send the first information to the first communication device through other messages, and there is no limitation on this.

[0014] In an alternative embodiment, the method further includes: receiving a first request message from the first communication device, where the first request message is used to request resetting the PDCP variables corresponding to the first multicast service or to request entering the RRC connected state; sending second information to the first communication device, where the second information is used to indicate the PDCP variables. The value to which the PDCP variables should be reset can be determined by the network device. Therefore, the network device can indicate the PDCP variables or the values of the PDCP variables to the first communication device, so that the first communication device can reset the PDCP variables. Among them, the first communication device can initiate a request to the network device when it wants to reset the PDCP variables, thereby improving the implementation flexibility of the first communication device; or whether to reset the PDCP variables can also be decided by the network device, then the first communication device does not have to request to reset the PDCP variables, which can simplify the implementation of the first communication device.

[0015] In a second aspect, another communication method is provided, and this method can be executed by a first communication device. The first communication device is, for example, a terminal device, or other device including the functions of a terminal device, or a chip system (or, chip) or other functional modules, and the chip system or functional module can implement the functions of a terminal device, and the chip system or functional module is, for example, disposed in a terminal device. The method includes: receiving first information, where the first information is used to indicate an RNA, and when all cells within the RNA provide a first multicast service for a communication device in the RRC idle state, the packet numbers of the first multicast service are synchronized.

[0016] In an alternative embodiment, the method further includes: receiving the first multicast service from a third cell in the RRC idle state, where the third cell belongs to the RNA, and the PDCP variables corresponding to the first multicast service remain unchanged.

[0017] In an alternative embodiment, the first information is further used to indicate that when all or some cells within the RNA provide the first multicast service for a communication device in the RRC connected state, the packet numbers of the first multicast service are synchronized.

[0018] In an alternative embodiment, the method further includes: camping on a third cell within the RNA in the RRC idle state; entering the RRC connected state in the third cell if the first multicast service from the first cell is not received; receiving the first multicast service in the RRC connected state, where the PDCP variables corresponding to the first multicast service remain unchanged.

[0019] In an alternative embodiment, the first information is used to indicate the RNA, including: the first information includes an identifier of a cell within the RNA; or, the first information includes an identifier of the RNA.

[0020] In an alternative embodiment, the first information is included in an RRC release message, and the RRC release message is used to release the first communication device to the RRC idle state.

[0021] Regarding the technical effects brought by the second aspect or various alternative embodiments, reference may be made to the introduction of the technical effects of the first aspect or the corresponding embodiments.

[0022] In a third aspect, another communication method is provided, which can be executed by a network device. The network device is, for example, a network equipment, or other equipment including network equipment functions, or a chip system (or, chip) or other functional modules, and the chip system or functional module can implement the functions of the network equipment. The chip system or functional module is, for example, disposed in the network equipment. Optionally, the network equipment is an access network equipment. Optionally, the access network equipment is, for example, a base station, or other equipment within the access network. The method includes: determining a first RNA of a first communication device, the first RNA including a first cell and a second cell; receiving third information from the second cell, the third information being used to indicate that the packet numbers of a first multicast service provided by the second cell to a communication device in the RRC idle state are out of sync; determining a second RNA of the first communication device, the second RNA including the first cell and not including the second cell; and sending fourth information, the fourth information being used to indicate the second RNA.

[0023] In the embodiments of the present application, there is no need to have excessive screening conditions when initially determining the RNA, which helps to simplify the process for the network device to determine the RNA. If the cell within the RNA can achieve synchronization when providing the first multicast service in the RRC idle state, the cell can continue to be retained within the RNA; while if the cell within the RNA fails to achieve synchronization when providing the first multicast service in the RRC idle state, the cell can be deleted from the RNA. Through this subsequent screening, all cells within the RNA can achieve synchronization when providing the first multicast service in the RRC idle state. Thus, for the UE, when moving between cells within the RNA, the manner in which these cells generate data packets of the first multicast service can be consistent, enabling the UE and these cells to maintain consistency for the data packets of the first multicast service and ensuring the normal transmission of the first multicast service. Moreover, the embodiments of the present application believe that if a cell within the RNA provides the first multicast service in the RRC idle state, the packet numbers of the first multicast service are synchronized when providing the first multicast service in the RRC idle state, thereby enabling each cell and the UE to have a consistent understanding of "synchronization".

[0024] In an alternative embodiment, the fourth information is included in the RRC release message, and the RRC release message is used to release the first communication device to the RRC idle state. For example, the network device can send the fourth information to the first communication device when releasing the first communication device, so that there is no need to send the fourth information through additional signaling, which is beneficial to saving signaling overhead. Or the network device can also send the fourth information through other messages, and there is no limitation on this.

[0025] In an alternative embodiment, the method further includes: sending a paging message; receiving an RRC resume message from the first communication device, where the resume reason value included in the RRC resume message is used to indicate RNA update. Before sending the RRC release message, the network device can first initiate paging so that the first communication device is paged, and thus the network device can send the fourth information through the RRC release message.

[0026] In an alternative embodiment, the paging message is further used to indicate RNA update. By indicating RNA update through the paging message, the first communication device can clearly know that this paging is not for entering the RRC connected state but for updating the RNA. Then the first communication device can indicate RNA update in the RRC resume message, thereby enabling RNA update without having to enter the RRC connected state.

[0027] In an alternative embodiment, the fourth information is included in a paging message, where the fourth information is used to indicate an updated RNA or indicate the second RNA. In this way, the network device can send the fourth information through the paging message, so that the communication device does not have to initiate an RRC resume procedure, which helps save signaling overhead and improves the RNA update efficiency.

[0028] In an alternative embodiment, fifth information is sent to at least one cell in the second RNA, and the fifth information is used to indicate the second RNA. After the RNA is updated, the network device can send the fifth information to the cells within the RNA to indicate these cells to update the RNA.

[0029] In a fourth aspect, another communication method is provided, which can be executed by a first communication device. The first communication device is, for example, a terminal device, or other device including the functions of a terminal device, or a chip system (or, chip) or other functional modules, and the chip system or functional module can implement the functions of the terminal device, and the chip system or functional module is, for example, disposed in the terminal device. The method includes: receiving a paging message from a first cell, where the paging message is used to indicate an updated RNA or indicate a second RNA; when the paging message is used to indicate an updated RNA, or indicate an updated RNA corresponding to a first multicast service, or indicate that a communication device receiving the first multicast service updates the RNA, determining the second RNA corresponding to the first communication device according to the paging message and the first RNA corresponding to the first communication device, where the second RNA does not include information of a second cell, and the first RNA includes information of the second cell.

[0030] Regarding the technical effects brought by the fourth aspect or various alternative embodiments, reference can be made to the introduction of the technical effects of the third aspect or the corresponding embodiments.

[0031] Fifth aspect, a communication device is provided. The communication device may be the network device described in any one of the first aspect to the fourth aspect above. The communication device has the functions of the above network device. The communication device is, for example, a network device, or other device including the functions of a network device, or a chip system (or, chip) or other functional module, and the chip system or functional module can implement the functions of a network device, and the chip system or functional module is, for example, disposed in a network device. In an optional implementation manner, the communication device includes a baseband device and a radio frequency device. In another optional implementation manner, the communication device includes a processing unit (sometimes also referred to as a processing module) and a transceiver unit (sometimes also referred to as a transceiver module). The transceiver unit can implement a sending function and a receiving function. When the transceiver unit implements the sending function, it can be referred to as a sending unit (sometimes also referred to as a sending module), and when the transceiver unit implements the receiving function, it can be referred to as a receiving unit (sometimes also referred to as a receiving module). The sending unit and the receiving unit may be the same functional module, and this functional module is called a transceiver unit, and this functional module can implement a sending function and a receiving function; or, the sending unit and the receiving unit may be different functional modules, and the transceiver unit is a general term for these functional modules.

[0032] In an optional implementation manner, the processing unit is configured to determine an RNA corresponding to a first communication device, and when all cells in the RNA provide a first multicast service to a communication device in the RRC idle state, the packet numbers of the first multicast service are synchronized; the transceiver unit (or, the sending unit) is configured to send first information to the first communication device, and the first information is used to indicate the RNA.

[0033] In an optional implementation manner, the processing unit is configured to determine a first RNA of a first communication device, and the first RNA includes a first cell and a second cell; the transceiver unit (or, the receiving unit) is configured to receive third information from the second cell, and the third information is used to indicate that the packet numbers of the first multicast service provided by the second cell to a communication device in the RRC idle state are not synchronized; the processing unit is further configured to determine a second RNA of the first communication device, and the second RNA includes the first cell and does not include the second cell; the transceiver unit (or, the sending unit) is configured to send fourth information, and the fourth information is used to indicate the second RNA.

[0034] In an optional implementation manner, the communication device further includes a storage unit (sometimes also referred to as a storage module), and the processing unit is configured to be coupled with the storage unit and execute programs or instructions in the storage unit to enable the communication device to execute the functions of the network device described in any one of the first aspect to the fourth aspect above.

[0035] In a sixth aspect, a communication device is provided. The communication device may be the first communication device described in any one of the first to fourth aspects above. The communication device has the functions of the first communication device. The communication device is, for example, a terminal device, or other device including the functions of a terminal device, or a chip system (or, chip) or other functional modules, and the chip system or functional module can implement the functions of a terminal device, and the chip system or functional module is, for example, disposed in a terminal device. In an optional implementation manner, the communication device includes a baseband device and a radio frequency device. In another optional implementation manner, the communication device includes a processing unit (sometimes also referred to as a processing module) and a transceiver unit (sometimes also referred to as a transceiver module). For the implementation manner of the transceiver unit, reference may be made to the description in the fifth aspect.

[0036] In an optional implementation manner, the transceiver unit (or, the receiving unit) is configured to receive first information, where the first information is used to indicate an RNA, and when all cells in the RNA provide a first multicast service for a communication device in the RRC idle state, the packet numbers of the first multicast service are synchronized.

[0037] In an optional implementation manner, the transceiver unit (or, the receiving unit) is configured to receive a paging message from a first cell, where the paging message is used to indicate an updated RNA or a second RNA; the processing unit is configured to, when the paging message is used to indicate an updated RNA, or indicate an updated RNA corresponding to a first multicast service, or indicate that a communication device receiving the first multicast service updates the RNA, determine the second RNA corresponding to the first communication device according to the paging message and the first RNA corresponding to the first communication device, where the second RNA does not include information of a second cell, and the first RNA includes information of the second cell.

[0038] In an optional implementation manner, the communication device further includes a storage unit (sometimes also referred to as a storage module), and the processing unit is configured to be coupled to the storage unit and execute programs or instructions in the storage unit to enable the communication device to execute the functions of the first communication device described in any one of the first to fourth aspects above.

[0039] In a seventh aspect, a communication device is provided. The communication device may be a network device, or a chip or chip system used in a network device. The communication device includes a communication interface and a processor. Optionally, a memory is further included. The memory is used to store a computer program, and the processor is coupled to the memory and the communication interface. When the processor reads the computer program or instruction, the communication device is enabled to execute the method performed by the network device in the above aspects.

[0040] In an eighth aspect, a communication device is provided, which may be a terminal device, or a chip or chip system used in a terminal device. The communication device includes a communication interface and a processor. Optionally, a memory is further included. The memory is used to store a computer program. The processor is coupled to the memory and the communication interface. When the processor reads the computer program or instruction, the communication device is caused to execute the method performed by the first communication device in the above aspects.

[0041] In a ninth aspect, a communication system is provided, including a network device and a first communication device. The network device is used to execute the method performed by the network device in the above first aspect or second aspect, and the first communication device is used to execute the method performed by the first communication device in the above first aspect or second aspect; or the network device is used to execute the method performed by the network device in the above third aspect or fourth aspect, and the first communication device is used to execute the method performed by the first communication device in the above third aspect or fourth aspect. For example, the network device may be implemented by the communication device in the fifth aspect or seventh aspect, and the first communication device may be implemented by the communication device in the sixth aspect or eighth aspect. Optionally, the communication system may further include other devices or apparatuses, such as other devices in addition to the network device and the first communication device, and no limitation is imposed thereon.

[0042] In a tenth aspect, a computer-readable storage medium is provided. The computer-readable storage medium is used to store a computer program or instruction. When the computer program or instruction is run, the method performed by the network device and / or the first communication device in the above aspects is implemented.

[0043] In an eleventh aspect, a computer program product including instructions is provided. When the computer program or instruction is run on a computer, the method in the above aspects is implemented.

[0044] In a twelfth aspect, a chip system is provided, including a processor and an interface. The processor is used to call and run an instruction from the interface, so that the chip system implements the method in the above aspects. Description of the Drawings

[0045] Figure 1 A schematic diagram of a kind of RNA;

[0046] Figure 2 A schematic diagram of a network architecture applied in an embodiment of the present application;

[0047] Figure 3 and Figure 4 Flowcharts of two communication methods provided by an embodiment of the present application;

[0048] Figure 5Schematic diagram of a device provided by an embodiment of the present application;

[0049] Figure 6 Schematic diagram of another device provided by an embodiment of the present application. Detailed implementation manners

[0050] In order to make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

[0051] In the embodiments of the present application, unless otherwise specified, for the number of nouns, it means "singular noun or plural noun", that is, "one or more". "At least one" means one or more, and "a plurality" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may mean: A exists alone, A and B exist simultaneously, and B exists alone, where A and B may be singular or plural. The character " / " generally means that the associated objects before and after are in an "or" relationship. For example, A / B means: A or B. "At least one (item)" or its similar expression below refers to any combination of these items, including any combination of a single item or plural items. For example, at least one (item) of a, b, or c means: a, b, c, a and b, a and c, b and c, or a, b, and c, where a, b, and c may be single or multiple.

[0052] In the embodiments of the present application, ordinal numbers such as "first" and "second" are used to distinguish multiple objects, and are not used to limit the size, content, order, time sequence, priority, or importance of multiple objects. In addition, for the numbering of steps in each embodiment introduced in the present application, it is only used to distinguish different steps and does not limit the sequence of steps. For example, S301 may occur before S302, or may occur after S302, or may also occur simultaneously with S302.

[0053] Hereinafter, some terms or concepts in the embodiments of the present application will be explained to facilitate the understanding of those skilled in the art.

[0054] (1) In the embodiments of the present application, the terminal device is a device with wireless transceiver functions, which can be a fixed device, a mobile device, a handheld device (such as a mobile phone), a wearable device, a vehicle-mounted device, or a wireless device (such as a communication module, a modem, or a chip system, etc.) built into the above devices. The terminal device is used to connect people, things, machines, etc., and can be widely used in various scenarios, such as including but not limited to the following scenarios: sensing scenarios, cellular communications, device-to-device (D2D) communications, vehicle-to-everything (V2X) communications, machine-to-machine / machine-type communications (M2M / MTC), Internet of Things (IoT), virtual reality (VR), augmented reality (AR), industrial control, self-driving, remote medical, smart grid, smart furniture, smart office, smart wearables, smart transportation, smart city, drones, robots, indoor commercial scenarios (such as mobile phone screen mirroring, file sharing, and video transmission from a mobile phone to a VR headset), etc. When the terminal device is applied to V2X, it can also be called a V2X device. For example, a smart car (smart car or intelligent car), a digital car, an unmanned car (unmanned car or driverless car or pilotless car or automobile), a self-driving car (self-driving car or autonomous car), a pure electric vehicle (pure EV or Battery EV), a hybrid electric vehicle (HEV), a range extended EV (REEV), a plug-in HEV (PHEV), a new energy vehicle, a road site unit (RSU). The terminal device can also be a device in D2D communications, such as an electricity meter, a water meter, etc.

[0055] In addition, in the embodiments of the present application, the terminal device may also be a terminal device in an IoT system. IoT is an important part of the future development of information technology. Its main technical feature is to connect objects to the network through communication technology, so as to achieve an intelligent network of human-machine interconnection and thing-thing interconnection.

[0056] Any of the various terminal devices introduced above, if located on a vehicle (such as placed inside or installed inside the vehicle), can be considered an in-vehicle terminal device. The in-vehicle terminal device is also called an on-board unit (OBU) for example. The terminal device of the present application may also be an in-vehicle module, in-vehicle module group, in-vehicle component, in-vehicle chip, or in-vehicle unit built into the vehicle as one or more components or units. The vehicle can implement the method of the present application through the built-in in-vehicle module, in-vehicle module group, in-vehicle component, in-vehicle chip, or in-vehicle unit.

[0057] The terminal device may sometimes be referred to as a user equipment (UE), a terminal, an access station, a UE station, a remote station, a wireless communication device, or a user device, etc.

[0058] In the embodiments of the present application, the communication device for implementing the functions of the terminal device may be the terminal device or a device capable of supporting the terminal device to implement such functions, such as a chip system. This communication device may be installed in the terminal device. In the technical solution provided in the embodiments of the present application, the technical solution provided in the embodiments of the present application is described by taking the communication device for implementing the functions of the terminal device as the terminal device as an example. Additionally, for convenience of description, the terminal device is described as a UE in the embodiments of the present application.

[0059] (2) The network device in the embodiments of the present application includes, for example, an access network device and / or a core network device. The access network device is a device with wireless transceiver functions and is used to communicate with the terminal device. The access network device includes, but is not limited to, a base station (base transceiver station (BTS), Node B, evolved Node B (eNodeB) / eNB, or next generation Node B (gNodeB) / gNB), a transmission reception point (TRP), a base station evolved by the 3rd generation partnership project (3GPP) in the future, an access node in a wireless fidelity (Wi-Fi) system, a wireless relay node, a wireless backhaul node, etc. The base station may be: a macro base station, a micro base station, a pico base station, a small station, a relay station, etc. Multiple base stations may support a network of the same access technology or networks of different access technologies. The base station may include one or more co-located or non-co-located transmission reception points. The access network device may also be a radio controller, a centralized unit (CU), and / or a distributed unit (DU) in a cloud radio access network (CRAN) scenario. The access network device may also be a server, etc. For example, the network device in V2X technology may be a road side unit (RSU). The following takes the base station as an example to illustrate the access network device. The base station may communicate with the terminal device or communicate with the terminal device through a relay station. The terminal device may communicate with multiple base stations in different access technologies. The core network device is used to implement functions such as mobility management, data processing, session management, policy and charging. The device names for implementing core network functions in systems of different access technologies may be different, and the embodiments of the present application do not limit this. Taking the 5th generation (5G) mobile communication technology system as an example, the core network device includes: an access and mobility management function (AMF), a session management function (SMF), a policy control function (PCF), or a user plane function (UPF), etc.

[0060] In the CU-DU architecture, the access network device may include one or more of logical network elements such as a central unit (CU), a distributed unit

[0061] (DU), a CU-control plane (CP), a CU-user plane (UP), or a radio unit (RU). The CU and the DU may be separately provided, or may also be included in the same network element, such as a baseband unit (BBU). The RU may be included in a radio frequency device or a radio frequency unit, such as being included in a remote radio unit (RRU), an active antenna unit (AAU), or a remote radio head (RRH).

[0062] In different systems, the CU (or CU-CP and CU-UP), DU, or RU may also have different names, but those skilled in the art can understand their meanings. For example, in the ORAN system, the CU may also be referred to as an open CU (O-CU), the DU may also be referred to as an O-DU, the CU-CP may also be referred to as an O-CU-CP, the CU-UP may also be referred to as an O-CU-UP, and the RU may also be referred to as an O-RU. For the convenience of description, in the embodiments of the present application, the CU, CU-CP, CU-UP, DU, and RU are taken as examples for description. Any one of the CU (or CU-CP, CU-UP), DU, and RU in the embodiments of the present application may be implemented by a software module, a hardware module, or a combination of a software module and a hardware module.

[0063] Optionally, in various embodiments of the present application, the actions performed by the cell (such as sending information to the UE, receiving information from the UE, or processing information, etc.) may specifically be performed by the network device providing the cell. Optionally, in various embodiments of the present application, if the network device has a distributed architecture, for example, the network device includes a CU and a DU, or includes a CU-CP, a CU-UP, and a DU, then when the network device sends information to the UE, specifically, it may be the DU included in the network device that sends information to the UE; when the network device receives information from the UE, specifically, it may be the DU included in the network device that receives information from the UE. Additionally, if the network device has a distributed architecture, for example, the network device includes a CU and a DU, or includes a CU-CP, a CU-UP, and a DU, then when the network device sends information to another network device, specifically, it may be the CU or the CU-CP included in the network device that sends information to the CU or the CU-CP of another network device; when the network device receives information from another network device, specifically, it may be the CU or the CU-CP included in the network device that receives information from the CU or the CU-CP of another network device.

[0064] In the embodiments of the present application, the communication device for implementing the functions of the network device may be the network device or a device capable of supporting the network device to implement such functions, such as a chip system, and this device may be installed in the network device. In the technical solutions provided in the embodiments of the present application, taking the device for implementing the functions of the network device as the network device as an example, the technical solutions provided in the embodiments of the present application are described.

[0065] (3) Multicast and broadcast service (MBS) is a service for multiple UEs, such as live broadcast services, public safety services, bulk software update services, etc. In the new radio (NR) system, MBS includes broadcast service and multicast service, where the multicast service is also referred to as the groupcast service. A UE can receive the groupcast service in the radio resource control (RRC) connected state. However, when the number of users receiving the groupcast service in a cell is too large, it may exceed the number of RRC connected state users that the cell can accommodate, which may lead to congestion and other phenomena. To alleviate network congestion, it is currently proposed to support UEs that join a multicast session to receive the multicast service in the RRC inactive state. A UE in the RRC disconnected state can use the point to multi-point (PTM) method to receive the multicast service according to the multicast configuration provided by the network device (such as what is called the multicast PTM configuration). For a multicast service, the corresponding multicast PTM configuration may include one or more of the following: the identifier of the multicast session (such as the temporary mobile group identity (TMGI)), the multicast MRB configuration (such as the PDCP configuration and / or radio link control (RLC) configuration of the multicast MRB, etc.), the group radio network temporary identifier (G-RNTI) used to de-scramble the multicast MBS traffic channel (MTCH), or, the multicast MTCH scheduling information.

[0066] (4) When the UE is in the RRC idle state, in order for the network to find the UE, the core network needs to send paging messages to all cells under all tracking areas (TAs) in the tracking area identity (TAI) list. This process is called terminal tracking at the core network level. Obviously, under this level of terminal tracking, since the vast majority of paging messages are sent to cells where the UE is not located, a relatively high paging message transmission overhead will be generated. If we want to save the transmission overhead, we need to narrow down the scope of paging message transmission. And to narrow down the scope of paging message transmission, the network side needs to manage a smaller granularity of the UE's location area. For a UE in the RRC idle state, the smallest granularity area managed by the network side is the TA of the core network. For a UE in the RRC inactive state, in order to further save the paging message transmission overhead, the concept of "RAN-based notification area (RNA)", which has a smaller scope than the TA, is introduced. The RNA is managed by the base station, and the base station can page the UE based on the RNA (RAN paging) to find the UE. This process is called terminal tracking at the radio access network level. As Figure 1 shown, cells can form larger RNAs, and each RNA corresponds to an RNA identifier (ID). RNAs can form larger TAs, and each TA corresponds to a TAI.

[0067] The following briefly introduces the technical features involved in the embodiments of this application.

[0068] For example, a UE in the RRC inactive state initially receives multicast services in a certain cell. Then the UE moves to a new cell, and the UE can continue to receive the multicast services in the new cell in the RRC inactive state. However, the ways of generating the PDCP COUNT of data packets in the source cell and the new cell may be inconsistent (that is, the PDCP COUNT is not synchronized), which may cause phenomena such as packet loss for the UE. For example, the UE receives multicast service A in the source cell and has received the 100th data packet of multicast service A (that is, the PDCP COUNT of this data packet is 100), and the content of the 100th data packet is, for example, "a". Then the UE moves to the new cell. The UE should receive the 101st data packet in the new cell. According to service continuity, the content of the 101st data packet should be "b". For the data packet with the content of "b" received from the core network in the new cell, the PDCP COUNT that the new cell should originally generate for it is 101. However, the ways of generating the PDCP COUNT of data packets in the source cell and the new cell may be inconsistent. Then the PDCP COUNT generated by the new cell for the data packet with the content of "b" may become 80, and this PDCP COUNT is not within the PDCP reception window of the UE, and the UE may discard this data packet. It can be seen that due to the unsynchronization of the PDCP COUNT between the source cell and the new cell, packet loss may occur for the UE, and even the amount of packet loss may be relatively large, affecting the reception of multicast service A by the UE.

[0069] In view of this, in the embodiments of the present application, the cells within the RNA can be synchronized when providing the first multicast service in the RRC disconnected state. For example, the network device can determine the RNA of the UE accordingly. Thus, the UE can be clear that when moving between the cells within the RNA, the ways of generating the PDCP COUNT of the data packets of the first multicast service in these cells can be consistent, so that both the UE and these cells can keep the PDCP COUNT of the data packets of the first multicast service consistent, ensuring the normal transmission of the first multicast service. Continuing with the above example. For example, the UE receives multicast service A in the source cell and has received the 100th data packet of multicast service A (that is, the PDCP COUNT of this data packet is 100), and the content of the 100th data packet is, for example, "a". Then the UE moves to the new cell. The UE should receive the 101st data packet in the new cell. According to service continuity, the content of the 101st data packet should be "b". Since the ways of generating the PDCP COUNT of data packets in the source cell and the new cell are consistent, the PDCP COUNT generated by the new cell for the data packet with the content of "b" will be 101. Then the UE can receive the 101st data packet in the new cell without discarding it. It can be seen that the embodiments of the present application enable the UE to receive multicast service A normally, improve service continuity, and also reduce the packet loss rate.

[0070] Moreover, based on the technical solution provided in the embodiments of the present application, the cells within the RNA can provide the first multicast service in the RRC idle state, and when providing the first multicast service in the RRC idle state, the packet numbers of the first multicast service are synchronized, so that each cell and UE can have a consistent understanding of "PDCP COUNT synchronization".

[0071] The technical solution provided in the embodiments of the present application can be applied to the fourth-generation mobile communication technology (the 4th generation, 4G) system, such as the LTE system, or can be applied to the fifth-generation mobile communication technology (the 5th generation, 5G) system, such as the NR system, or can also be applied to the next-generation mobile communication system or other similar communication systems, such as the sixth-generation mobile communication technology (the 6th generation, 6G) system, etc., without specific limitation. In addition, the technical solution provided in the embodiments of the present application can be applied to the D2D scenario, such as the NR-D2D scenario, etc., or applied to the V2X scenario, such as the NR-V2X scenario, etc. For example, the embodiments of the present application can be used in fields such as factory manufacturing, whole-house intelligence, intelligent driving, assisted driving, intelligent connected vehicles, or indoor commercial scenarios.

[0072] For reference Figure 2 , which is a communication network architecture applicable to the embodiments of the present application. Figure 2 It includes a UE, network device 1, and network device 2. For example, the UE can move between the cells provided by these two network devices. When moving to one of the network devices (for example, camping on a certain cell provided by the network device), the UE can communicate with the network device. Or the UE may only move between different cells provided by one network device, in which case there may only be one network device; or the UE can also move between the cells provided by more network devices, in which case there may be more network devices. Figure 2 Taking the case of two network devices as an example. Figure 2 The UE and network devices in can execute the method provided in the embodiments of the present application.

[0073] To better introduce the embodiments of the present application, the method provided in the embodiments of the present application will be described below with reference to the accompanying drawings. In each embodiment of the present application, the RRC idle state of the UE may refer to a state where there is no connection between the RRC layer of the UE and the RRC layer of the access network device, such as including the RRC idle state or the RRC inactive state. In the following text, unless otherwise specified, in the accompanying drawings corresponding to the embodiments of the present application, the steps represented by dashed lines are all optional steps.

[0074] Each embodiment of the present application can be executed by a communication device and a network device. The communication device is, for example, a UE, or a functional module capable of executing the method provided by the embodiments of the present application. This functional module can be set in the UE, for example, a chip system in the UE; or this functional module can also be set independently of the UE. The network device is, for example, a network equipment, or a functional module capable of executing the method provided by the embodiments of the present application. This functional module can be set in the network equipment, for example, a chip system in the network equipment; or this functional module can also be set independently of the network equipment. In the following introduction, it is taken as an example that the communication device is a UE and the network device is a network equipment. The methods provided by each embodiment of the present application can be applied to Figure 2 the network architecture shown. For example, the first UE involved in each embodiment of the present application can be Figure 2 the UE in; the first network equipment involved in each embodiment of the present application can be Figure 2 the network equipment 1 in; the second network equipment involved in each embodiment of the present application can be Figure 2 the network equipment 2 in.

[0075] Before introducing the embodiments of the present application, the multicast service is briefly introduced. The multicast service is designed for services with high quality of service (QoS) requirements. For example, for the multicast service, the same QoS level as the unicast service can be provided. For the multicast service, group management can be provided. Specifically, for the multicast service, the core network can manage the joining and leaving of the UE. The multicast session corresponding to the multicast service (such as an MBS session) can be established based on the already established PDU session, and a new QoS flow, called MBS QoS flow, is introduced for the multicast session. For network equipment (such as access network equipment), it can support sending multicast service data to the UE through point-to-point (PTP) or point-to-multipoint (PTM) transmission modes, and the network equipment (such as access network equipment) can also control the dynamic switching of the multicast service transmission mode between PTP and PTM. In addition, for the multicast service, it can also support the deactivation or activation of the MBS session triggered by the core network, and the UE can be unaware of the state of the multicast service, for example, it is not aware that the MBS session is activated or deactivated.

[0076] The embodiments of the present application provide a communication method. Please refer to Figure 3 for the flowchart of this method.

[0077] S301. The second cell determines the RNA corresponding to the first UE. For example, S301 may be executed by a network device (such as the first network device) that provides the second cell.

[0078] For example, when the second cell is to release the first UE to the RRC idle state, it may determine the RNA corresponding to the first UE; or, the second cell may periodically determine the RNA corresponding to the first UE; or the second cell may also determine the RNA corresponding to the first UE under other triggering conditions. There is no specific limitation.

[0079] Optionally, the second cell may determine the RNA corresponding to the first UE according to the information of at least one cell. Optionally, the information of any one cell in the information of at least one cell may include the capability information of the cell, or may also include other information of the cell. The at least one cell may include the cells provided by the first network device and / or other network devices other than the first network device. For example, the first network device may interact with other network devices through the Xn interface, and the other network devices may send the information of some or all of the cells provided by the other network devices to the first network device, whereby the second cell may determine the information of at least one cell. For example, the second cell (specifically the first network device) may send a request to the other network device, such as a request A, and the request A may request the information of the cells provided by the other network device; after receiving the request A, the other network device may send a response to the second cell (specifically to the first network device), such as a response A, and the response A may include (or indicate) the information of some or all of the cells provided by the other network device. Optionally, the first network device may also send the information of some or all of the cells provided by the first network device to the other network devices, or indicate whether some or all of the cells provided by the first network device support synchronization when the first multicast service is provided to the UE in the RRC idle state. In various embodiments of the present application, "synchronization" may refer to PDCP COUNT synchronization, and in this article, "PDCP COUNT synchronization" may also be abbreviated as "synchronization", and this concept will be introduced later. For example, this information or this indication is included in the request A, or the first network device may also send this information or this indication to the other network device after receiving a request from the other network device, so that the other network device can also determine the RNA corresponding to the UE covered by the other network device accordingly.

[0080] Optionally, the information interaction may be performed in the Xn setup process. For example, Request A is an Xn setup request, and Response A is an Xn setup response. Alternatively, the information interaction may also be performed in the next generation (NG)-RAN node configuration update process. For example, Request A is an NG-RAN node configuration update message, and Response A is an NG-RAN node configuration update acknowledgement message. Alternatively, the information interaction may also be performed in other processes, or a dedicated process for capability interaction may be added. There is no restriction on this.

[0081] Alternatively, the first network device may also obtain information about some or all of the cells provided by other network devices without interacting with other network devices. For example, the first network device may obtain information about some or all of the cells provided by other network devices based on operation administration and maintenance (OAM) or other means.

[0082] Among them, the information of a cell may indicate whether the packet numbers of the first multicast service are synchronized when the cell provides the first multicast service to a UE in the RRC idle state. The first multicast service includes, for example, some or all of the multicast services received (or joined) by the first UE. For example, the first multicast service includes all of the multicast services received or joined by the first UE, or the first multicast service includes a certain multicast service received or joined by the first UE. Among them, the packet number is, for example, the PDCP COUNT corresponding to the packet, and hereinafter the PDCP COUNT may also be simply referred to as COUNT. Therefore, the information of a cell may also be simply described as that the information of a cell may indicate whether the cell supports PDCP COUNT synchronization in the RRC idle state for the first multicast service.

[0083] Among them, a cell supporting PDCP COUNT synchronization for a certain multicast service can be understood as, when the cell provides the multicast service to the UE, the data packet number of the multicast service is synchronized with the data packet number of the multicast service provided by other cells to the UE (for example, the data packet number of the multicast service provided by the cell changes synchronously with the data packet number of the multicast service provided by other cells, and remains the same). Optionally, cell A and cell B both support PDCP COUNT synchronization for the first multicast service, which indicates that cell A and cell B can map the same quality of service (QoS) flow for transmitting the first multicast service to the same MRB, and cell A and cell B can both generate the PDCP COUNT of the data packet transmitted by the MRB based on the MBS QoS flow identifier (QFI) SN of the QoS flow corresponding to the MRB transmitting the first multicast service. Among them, cell A and cell B can receive QoS parameters of QoS flow for transmitting the first multicast service from the core network, and the QoS parameters correspond to the first multicast service, or correspond to the MBS session for transmitting the first multicast service, so the QoS parameters for the same QoS flow issued by the core network are the same. Then for cell A and cell B, the received QoS parameters corresponding to the same QoS flow are the same, so it is considered that the QoS flows for transmitting the first multicast service in cell A and cell B are the same QoS flows. For example, the core network issues QoS parameter A of QoS flow1 for transmitting the first multicast service and QoS parameter B of QoS flow2, and cell A and cell B will receive the QoS parameter A and QoS parameter B. Therefore, for cell A and cell B, the QoS flows for transmitting the first multicast service include QoS flow1 and QoS flow2, and their corresponding QoS parameters are also the same. If both cell A and cell B support PDCP COUNT synchronization of the first multicast service, cell A and cell B may map QoS flow1 to the same MRB, and also map QoS flow2 to the same MRB. These two MRBs may be the same MRB or different MRBs.

[0084] Based on the above, if a cell supports PDCP COUNT synchronization for a certain multicast service in the RRC idle state, it can be understood that when this cell provides the multicast service to a UE in the RRC idle state, the packet numbers of the multicast service are synchronized with those of other cells that provide the same multicast service to UEs in the RRC idle state. Optionally, the other cells can be cells that have already achieved PDCP COUNT synchronization in the RRC idle state. Herein, the cell described as "having achieved PDCP COUNT synchronization in the RRC idle state" refers to the cell in which the PDCP COUNT of the multicast service has achieved synchronization in the RRC idle state.

[0085] For example, both cell A and cell B support PDCP COUNT synchronization for multicast service A in the RRC idle state. After cell B has been sending multicast service A on MRB 1 for a period of time, cell A starts to send the RRC idle state multicast service A on MRB 1. For example, when cell A starts to send multicast service A, the COUNT of the packets of multicast service A sent by cell B on a certain QoS flow corresponding to MRB 1 is 100. Since cell A will use the same rule as cell B to generate the PDCP COUNT of the packets of multicast service A, the PDCP COUNT of the packets of multicast service A sent by cell A on a certain QoS flow corresponding to MRB 1 will also start counting from 100 (where cell A and cell B may not know the PDCP COUNT of the packets of multicast service A sent by the other party, but because the rules for generating the PDCP COUNT by cell A and cell B are the same, the PDCP COUNT of the packets of multicast service A generated by cell A and cell B will be the same), thereby achieving synchronization of the multicast service A among the cells.

[0086] Among them, if the information of a cell indicates that the cell supports PDCP COUNT synchronization for the first multicast service in the RRC idle state, it also indicates that the cell can provide the first multicast service to a UE in the RRC idle state. Therefore, optionally, if the information of a cell indicates that the cell supports PDCP COUNT synchronization for the first multicast service in the RRC idle state, the information of the cell may not need to indicate whether the cell can provide the first multicast service to a UE in the RRC idle state; and if the information of a cell indicates that the cell does not support PDCP COUNT synchronization for the first multicast service in the RRC idle state, the information of the cell can also indicate whether the cell can provide the first multicast service to a UE in the RRC idle state, or it may not need to indicate whether the cell can provide the first multicast service to a UE in the RRC idle state anymore.

[0087] Optionally, the information of a cell may also indicate whether the packet numbers of the first multicast service are synchronized when the cell provides the first multicast service to a UE in the RRC connected state. This can also be simply described as that the information of a cell may also indicate whether the cell supports PDCP COUNT synchronization in the RRC connected state for the first multicast service. A cell supporting PDCP COUNT synchronization in the RRC connected state for a certain multicast service can be understood as that when the cell provides the multicast service to a UE in the RRC connected state, the packet numbers of the multicast service are synchronized with those of the same multicast service provided by other cells to UEs in the RRC connected state. Optionally, the other cells may be cells that have implemented PDCP COUNT synchronization in the RRC connected state. Herein, the cell described as having "implemented PDCP COUNT synchronization in the RRC connected state" refers to the cell that has implemented PDCP COUNT synchronization in the RRC connected state for the multicast service.

[0088] Optionally, the information of a cell may also indicate whether the cell can provide the first multicast service to a UE in the RRC connected state. If the information of a cell indicates that the cell supports PDCP COUNT synchronization in the RRC connected state for the first multicast service, it also means that the cell can provide the first multicast service to a UE in the RRC connected state. Therefore, optionally, if the information of a cell indicates that the cell supports PDCP COUNT synchronization in the RRC connected state for the first multicast service, the information of the cell may not need to indicate whether the cell can provide the first multicast service to a UE in the RRC connected state; if the information of a cell indicates that the cell does not support PDCP COUNT synchronization in the RRC connected state for the first multicast service, the information of the cell may also indicate whether the cell can provide the first multicast service to a UE in the RRC connected state, or it may not need to indicate whether the cell can provide the first multicast service to a UE in the RRC connected state anymore.

[0089] If the information of a cell needs to indicate whether the cell supports PDCP COUNT synchronization in the RRC connected state for the first multicast service and also needs to indicate whether the cell supports PDCP COUNT synchronization in the RRC idle state for the first multicast service, then these two capabilities can be indicated separately. For example, the other network device includes a second network device, and the second network device provides the information of cell 2 to the first network device. For example, this information occupies two bits. Among them, bit A corresponds to the RRC connected state, and bit B corresponds to the RRC idle state. If the value of bit A is "1" or "true" or "support", or the bit exists, it means that cell 2 supports PDCP COUNT synchronization in the RRC connected state for the first multicast service; if the value of bit A is "0" or "false" or "not - support", or the bit does not exist, it means that cell 2 does not support PDCP COUNT synchronization in the RRC connected state for the first multicast service. If the value of bit B is "1" or "true" or "support", or the bit exists, it means that cell 2 supports PDCP COUNT synchronization in the RRC idle state for the first multicast service; if the value of bit B is "0" or "false" or "not - support", or the bit does not exist, it means that cell 2 does not support PDCP COUNT synchronization in the RRC idle state for the first multicast service.

[0090] Alternatively, if the information of a cell needs to indicate whether the cell supports PDCP COUNT synchronization in the RRC connected state for the first multicast service and also needs to indicate whether the cell supports PDCP COUNT synchronization in the RRC idle state for the first multicast service, then these two capabilities can be indicated jointly. For example, the other network device includes a second network device, and the second network device provides the information of cell 2 to the first network device. For example, this information occupies one bit. If the value of this bit is "1" or "true" or "support", or the bit exists, it means that cell 2 supports PDCP COUNT synchronization in the RRC idle state and supports PDCP COUNT synchronization in the RRC connected state for the first multicast service; if the value of this bit is "0" or "false" or "not - support", or the bit does not exist, it means that cell 2 does not support PDCP COUNT synchronization in the RRC idle state and does not support PDCP COUNT synchronization in the RRC connected state for the first multicast service.

[0091] How the network device indicates the information of the cell provided by the network device may depend on the implementation of the network device or on how the cell information is predefined. For example, if the protocol predefines that a certain cell information refers to whether the cell supports PDCP COUNT synchronization in the RRC connected state and whether it supports PDCP COUNT synchronization in the RRC idle state for multicast services, then these two capabilities are regarded as one capability and can be combined for indication; or, if the protocol predefines two cell information, one is whether the cell supports PDCP COUNT synchronization in the RRC connected state for multicast services, and the other is whether the cell supports PDCP COUNT synchronization in the RRC idle state for multicast services, then these two capabilities can be indicated separately.

[0092] In the embodiments of this application, the second cell may add a cell that meets the following conditions to the RNA corresponding to the first UE: capable of providing a first multicast service in the RRC idle state, and supporting PDCP COUNT synchronization in the RRC idle state for the first multicast service. Among them, when the second cell determines the RNA, the cells added to the RNA do not necessarily provide the first multicast service to the RRC idle state UE, as long as these cells have the ability to provide the first multicast service to the RRC idle state UE. It can also be considered that all cells included in the RNA corresponding to the first UE can provide the first multicast service to the RRC idle state UE (but when the second cell determines the RNA, the cells in the RNA do not necessarily provide the first multicast service to the RRC idle state UE, as long as these cells have the ability to provide the first multicast service to the RRC idle state UE), and support PDCP COUNT synchronization in the RRC idle state for the first multicast service. This can also be described as that the cells in the RNA support PDCP COUNT synchronization for the first multicast service, and this PDCP COUNT synchronization can include PDCP COUNT synchronization in the RRC idle state. For example, the second cell obtains the information of cells 1 to 4, and the information of each of cells 1 to 3 indicates that the cell can provide the first multicast service to the RRC idle state UE and supports PDCP COUNT synchronization in the RRC idle state for the first multicast service, then the second cell can add cells 1 to 3 to the RNA corresponding to the first UE. And the information of cell 4 indicates that cell 4 does not support PDCP COUNT synchronization in the RRC idle state for the first multicast service, then the second cell may not add cell 4 to the RNA corresponding to the first UE.

[0093] Alternatively, the second cell may add a cell that meets the following conditions to the RNA corresponding to the first UE: capable of providing the first multicast service in the RRC idle state, and supporting PDCP COUNT synchronization for the first multicast service in the RRC idle state, and capable of providing the first multicast service in the RRC connected state, and supporting PDCP COUNT synchronization for the first multicast service in the RRC connected state. Among them, when the second cell determines this RNA, the cells added to this RNA do not necessarily provide the first multicast service to the RRC idle state UE, as long as these cells have the ability to provide the first multicast service to the RRC idle state UE; in addition, when the second cell determines this RNA, the cells added to this RNA do not necessarily provide the first multicast service to the RRC connected state UE, as long as these cells have the ability to provide the first multicast service to the RRC connected state UE. It can also be considered that all cells included in the RNA corresponding to this UE can provide the first multicast service to the RRC idle state UE, and support PDCP COUNT synchronization for the first multicast service in the RRC idle state; and all cells included in the RNA corresponding to the first UE can provide the first multicast service to the RRC connected state UE, and support PDCP COUNT synchronization for the first multicast service in the RRC connected state. This can also be described as that the cells in the RNA support PDCP COUNT synchronization for the first multicast service, and this PDCP COUNT synchronization can include PDCP COUNT synchronization in the RRC idle state and PDCP COUNT synchronization in the RRC connected state.

[0094] S302. The second cell sends the first information to the first UE. Correspondingly, the first UE receives the first information. For example, S302 may be executed by the first network device providing the second cell.

[0095] After the second cell determines the RNA corresponding to the first UE, it may indicate this RNA to the first UE through the first information. The first information indicates this RNA. For example, one indication method is that the second information includes the identifier of this RNA. The identifier of this RNA is, for example, an RNA code, or an index of the RNA, etc. Among them, if the second information includes this RNA code, the second cell may determine the cell range corresponding to the RNA code in advance based on methods such as OAM or protocol predefinition to determine the RNA code corresponding to this RNA.

[0096] Alternatively, another indication method for the second information to indicate this RNA is that the second information includes the identifiers of the cells in this RNA. For example, the second information may include a cell list, and this cell list includes the identifiers of all cells in this RNA. The identifier of a cell is, for example, the identity number (ID) of the cell.

[0097] Optionally, the first information may further indicate that all cells within the RNA support PDCP COUNT synchronization in the RRC idle state for the first multicast service. For example, if the RNA does not correspond to the relationship that "all cells within the RNA support PDCP COUNT synchronization in the RRC idle state for the first multicast service", then in addition to indicating the RNA, the first information may further indicate that all cells within the RNA support PDCP COUNT synchronization in the RRC idle state for the first multicast service. Or, if the RNA corresponds to the relationship that "all cells within the RNA support PDCP COUNT synchronization in the RRC idle state for the first multicast service", that is, the first UE can be clear that as long as it is the RNA configured by the network device, all cells within the RNA support PDCP COUNT synchronization in the RRC idle state for the first multicast service, then the first information may not need to indicate that all cells within the RNA support PDCP COUNT synchronization in the RRC idle state for the first multicast service, but only needs to indicate the RNA, which helps to save the overhead of the first information.

[0098] Optionally, the first information may further indicate whether all or some of the cells within the RNA support PDCP COUNT synchronization in the RRC connected state for the first multicast service. For example, if the RNA only associates that all cells within the RNA support PDCP COUNT synchronization in the RRC idle state for the first multicast service, but does not associate that the cells within the RNA support PDCP COUNT synchronization in the RRC connected state for the first multicast service, or the RNA is not associated with either of the above two relationships, then if all or some of the cells within the RNA support PDCP COUNT synchronization in the RRC connected state for the first multicast service, the second cell may indicate it through the first information. If the RNA associates that all or some of the cells within the RNA support PDCP COUNT synchronization in the RRC connected state for the first multicast service, then the first UE can clarify the meaning of the PDCP COUNT synchronization associated with the RNA, and the first information may not need to additionally indicate that all or some of the cells within the RNA support PDCP COUNT synchronization in the RRC connected state for the first multicast service. As an optional implementation manner, if some of the cells within the RNA support PDCP COUNT synchronization in the RRC connected state for the first multicast service, the first information may further indicate (or include) the identifiers of these cells, so that the first UE can clarify which cells exactly support PDCP COUNT synchronization in the RRC connected state for the first multicast service. Alternatively, even if some of the cells within the RNA support PDCP COUNT synchronization in the RRC connected state for the first multicast service, the first information may not indicate these cells, then for the first UE, it may not be able to clarify which cells within the RNA exactly support PDCP COUNT synchronization in the RRC connected state for the first multicast service, or the first UE can also determine which cells within the RNA exactly support PDCP COUNT synchronization in the RRC connected state for the first multicast service through other means.

[0099] As an optional implementation manner of the first information, for example, the first information is included in the RRC release message, or the first information may be the RRC release message. The RRC release message can be used to release the first UE to the RRC idle state, or to release the first UE to the RRC idle state to receive the first multicast service. For example, if the second cell under the first network device releases the first UE to the RRC idle state, the RRC release message may be sent by the second cell. Alternatively, the first information may also be included in other messages, for example, the first information may be sent before releasing the UE, etc., and there is no limitation on this.

[0100] S303. The first UE enters the first cell in the RRC idle state. The first cell may be a cell provided by the first network device, or may also be a cell provided by other network devices (such as the second network device).

[0101] For example, after the first UE is released to the RRC idle state in the second cell and moves to the first cell, the first UE can camp on the first cell in the RRC idle state. For example, the first UE reselects to the first cell. Both the first cell and the second cell can be cells within the RNA corresponding to the first UE.

[0102] S304. The first cell sends a first multicast service to the UE in the RRC idle state. Correspondingly, the first UE receives the first multicast service from the first cell in the RRC idle state. Among them, when the first cell sends the first multicast service, specifically, it can be the network device of the first cell that sends the first multicast service.

[0103] For example, if the first cell provides a first multicast service to the UE in the RRC idle state (for example, when the first UE moves to the first cell, the first cell is providing a first multicast service to the UE in the RRC idle state), then the first UE can receive the first multicast service from the first cell in the RRC idle state.

[0104] Optionally, if the first UE in the RRC idle state obtains the configuration of the first multicast service through a multicast MBS control channel (MCCH) message or a system message (such as a system information block (SIB)) in the first cell, it can be determined that the first cell provides the first multicast service to the UE in the RRC idle state; or, if the first UE in the RRC idle state does not obtain the configuration of the first multicast service through a multicast MCCH message or a system message in the first cell, it can be determined that the first cell does not provide the first multicast service to the UE in the RRC idle state. Alternatively, the first UE can also determine whether the first cell provides the first multicast service to the UE in the RRC idle state by other means, and this is not limited.

[0105] If the first cell provides the first multicast service to the UE in the RRC idle state, the first UE can receive the first multicast service from the first cell in the RRC idle state without having to enter the RRC connected state in the first cell. Optionally, the first UE may not need to reset the PDCP variables corresponding to the first multicast service, or may not need to reset the values of the PDCP variables. Optionally, the PDCP variables can be used by the first UE to maintain the reception window of the first UE for the first multicast service, and the first UE can receive the data packets of the first multicast service according to this reception window. For example, the value of the PDCP variable can be the value of the lower boundary of the reception window. For example, the PDCP variable can indicate the number of the first data packet of the first multicast service that has not been delivered to the upper layer by the PDCP layer of the first UE. As an alternative implementation, the PDCP variable maintained by the first UE is, for example, the received (RX)_delivered (DELIV) maintained by the first UE. The "RX_DELIV" identifies the PDCP COUNT of the first PDCP service data unit (SDU) that has not been delivered to the upper layer by the PDCP layer, or is described as this state variable indicating the COUNT value of the first PDCP SDU, which has not been passed to the upper layer but is still awaited. The PDCP variable can be used by the UE to determine the PDCP COUNT of the received data packets.

[0106] It can be seen that since the first cell is a cell within the RNA of the first UE, and the cells within this RNA can support the PDCP COUNT synchronization in the RRC idle state for the first multicast service, the rules for generating the PDCP COUNT of the data packets of the first multicast service by the cells within this RNA are the same, and the PDCP COUNT of the data packets of the first multicast service generated by the cells within this RNA is also the same. Therefore, the first UE does not need to change the value of the PDCP variable, but can continue to use the original value of the PDCP variable to keep the PDCP reception window in continuous use.

[0107] S305. If the first multicast service from the first cell is not received in the RRC idle state, the first UE enters the RRC connected state in the first cell to receive the first multicast service. Among them, S304 and S305 are two parallel steps, and either one can be executed according to the situation.

[0108] Optionally, the first UE may maintain a timer. For example, the first UE starts the timer when it camps on the first cell. When the timer expires, if the first UE has not received the first multicast service from the first cell, the first UE may enter the RRC connected state in the first cell to receive the first multicast service in the RRC connected state.

[0109] Alternatively, for what is described in S305, "not receiving the first multicast service from the first cell" may also be understood as "the first cell does not provide the first multicast service to the UE in the RRC idle state". For example, the first UE may determine whether the first cell provides the first multicast service to the UE in the RRC idle state according to the method described in S304. If the first cell does not provide the first multicast service to the UE in the RRC idle state, the first UE may enter the RRC connected state in the first cell to receive the first multicast service in the RRC connected state.

[0110] Among them, if the first cell can support PDCP COUNT synchronization in the RRC connected state for the first multicast service (the first UE can determine this according to the RNA, or according to the indication of the first information), the first UE may not reset the PDCP variable corresponding to the first multicast service, so that PDCP COUNT synchronization of the first multicast service can be achieved between each cell and the first UE.

[0111] Alternatively, if the first cell does not support PDCP COUNT synchronization in the RRC connected state for the first multicast service, or the first UE cannot determine whether the first cell supports PDCP COUNT synchronization in the RRC connected state for the first multicast service (for example, the RNA is not associated with "the cells in the RNA support PDCP COUNT synchronization in the RRC connected state for the first multicast service", and the first information does not indicate whether the cells in the RNA support PDCP COUNT synchronization in the RRC connected state for the first multicast service; or for another example, the first information indicates that some cells in the RNA support PDCP COUNT synchronization in the RRC connected state for the first multicast service, but the first UE cannot determine which cells exactly support PDCP COUNT synchronization in the RRC connected state for the first multicast service), the first UE may reset the PDCP variable corresponding to the first multicast service, so that the packet numbers of the first multicast service of the first UE and the first cell are kept consistent.

[0112] Among them, if the first UE wants to reset the PDCP variables corresponding to the first multicast service, it can obtain the PDCP variables or obtain the updated values of the PDCP variables. As an optional implementation manner for the first UE to obtain the updated values, when the PDCP variables need to be updated, the first UE may send a first request message to the first cell (for example, to the second network device), and the first request message can be used to request an update of the PDCP variables. After receiving the first request message, the first cell may send second information to the first UE, and the second information may indicate the PDCP variables or indicate the values of the PDCP variables (the values are updated values, for example). Optionally, the second information may be included in the RRC message. For example, the second information is the initial RX-DELIV cell in the RRC message. Optionally, the first request message may be an RRC resume request message sent by the first UE to the first cell, or the first request message may be included in the RRC resume request message, or the first request message may also be included in other messages during the RRC resume process executed by the first UE. For example, if the first UE wants to enter the RRC connected state in the first cell, it can be achieved by initiating the RRC resume process. Then, the first UE may send the RRC resume request to the first cell to request to enter the RRC connected state.

[0113] As another optional implementation manner, whether the first UE needs to reset the PDCP variables may also be determined by the first cell instead of the first UE. Then, if the first cell supports the PDCP COUNT synchronization in the RRC connected state for the first multicast service, the first cell does not have to send the PDCP variables to the first UE or does not send the updated values of the PDCP variables; if the first UE does not receive the PDCP variables or the updated values of the PDCP variables, it may not reset the PDCP variables. Or, if the first cell does not support the PDCP COUNT synchronization in the RRC connected state for the first multicast service, the first cell may send the PDCP variables to the first UE or send the updated values of the PDCP variables; if the first UE receives the PDCP variables or the updated values of the PDCP variables, it may reset the PDCP variables. For example, after the first cell receives the RRC resume process initiated by the first UE (for example, receives the RRC resume request from the first UE), if the first cell does not support the PDCP COUNT synchronization in the RRC connected state for the first multicast service, the first cell may send the first information to the first UE; if the first cell supports the PDCP COUNT synchronization in the RRC connected state for the first multicast service, the first cell does not have to send the first information to the first UE.

[0114] After the first UE obtains the PDCP variable or an updated value of the PDCP variable, it may update the PDCP variable corresponding to the first multicast service accordingly, so that the packet numbers of the first multicast service of the first UE and the first cell are kept consistent.

[0115] In the embodiments of the present application, the cells within the RNA can achieve PDCP COUNT synchronization when providing the first multicast service in the RRC idle state. For example, the network device can determine the RNA of the UE accordingly. Thus, the UE can be clear that when moving between the cells within the RNA, the manner of generating the PDCP COUNT of the packets of the first multicast service by these cells can be consistent, so that both the UE and these cells can keep the PDCP COUNT of the packets of the first multicast service consistent, ensuring the normal transmission of the first multicast service. Based on the technical solution provided by the embodiments of the present application, the cells within the RNA can provide the first multicast service in the RRC idle state, and when providing the first multicast service in the RRC idle state, the packet numbers of the first multicast service are synchronized, so that each cell and the UE within the RNA can have a consistent understanding of "PDCP COUNT synchronization".

[0116] The embodiments of the present application provide another communication method. Please refer to Figure 4 , which is a flowchart of this method.

[0117] S401. The first cell determines the RNA corresponding to the first UE, for example, referred to as the first RNA. For example, S401 may be executed by the first network device providing the first cell.

[0118] For example, when the first cell is about to release the first UE to the RRC idle state, it may determine the RNA corresponding to the first UE; or, the first cell may periodically determine the RNA corresponding to the first UE; or the first cell may also determine the RNA corresponding to the first UE under other triggering conditions. There is no specific limitation.

[0119] Among them, there is no limitation on whether the cells within the first RNA can support PDCP COUNT synchronization for the first multicast service.

[0120] That is, the cells within the first RNA may or may not support PDCP COUNT synchronization for the first multicast service. The PDCP COUNT synchronization may include PDCP COUNT synchronization in the RRC idle state and / or may include PDCP COUNT synchronization in the RRC connected state. For example, the cells within the first RNA may or may not support PDCP COUNT synchronization in the RRC idle state for the first multicast service; the cells within the first RNA may or may not support PDCP COUNT synchronization in the RRC connected state for the first multicast service.

[0121] Alternatively, the first cell may assume that all cells within the first RNA support PDCP COUNT synchronization in the RRC idle state for the first multicast service. In fact, the cells within the first RNA may or may not support PDCP COUNT synchronization in the RRC idle state for the first multicast service. There may be no restriction on whether the cells within the first RNA can support PDCP COUNT synchronization in the RRC connected state for the first multicast service.

[0122] For the introduction of content such as PDCP COUNT synchronization, reference can be made to Figure 3 the embodiments shown.

[0123] In addition, the cells within the first RNA may or may not have the ability to provide the first multicast service to UEs in the RRC idle state; the cells within the first RNA may or may not have the ability to provide the first multicast service to UEs in the RRC connected state. For example, when the first RNA is determined, the cells within the first RNA may not provide the first multicast service to UEs in the RRC idle state; or, when the first RNA is determined, the cells within the first RNA may already be providing the first multicast service to UEs in the RRC idle state, but these cells support PDCP synchronization in the RRC idle state for the first multicast service (optionally, for these situations, the first cell may not be aware). The first multicast service includes, for example, all or part of the multicast services received or joined by the first UE.

[0124] Optionally, when determining the first RNA, the first cell may send a message to the cell to be included in the first RNA to indicate that the cell is to be included in the first RNA. For example, this message may be referred to as message A. For example, if the first cell wants to include cell A in the first RNA, the first cell may send message A to cell A. For the cell that receives message A, it may send a response message to the first cell. Among them, if a certain cell does not provide the first multicast service to the RRC idle-mode UE when receiving message A, or although the cell has started to provide the first multicast service to the RRC idle-mode UE, but the cell supports RRC idle-mode PDCP COUNT synchronization for the first multicast service, the response message sent by the cell may indicate successful reception of message A, that is, the response message may only be a response to message A without indicating other content. If the first cell receives such a response message, the first cell may include the cell that sends such a response message in the first RNA.

[0125] Alternatively, if a certain cell has started to provide the first multicast service to the RRC idle-mode UE when receiving message A, and the cell does not support RRC idle-mode PDCP COUNT synchronization for the first multicast service, the response message sent by the cell may indicate that the cell does not support RRC idle-mode PDCP COUNT synchronization for the first multicast service, or indicate that the cell has started to provide the multicast service to the RRC idle-mode UE and that the cell does not support RRC idle-mode PDCP COUNT synchronization for the first multicast service. If the first cell receives such a response message, the first cell may not include the cell that sends such a response message in the first RNA, that is, the first RNA determined by the first cell will not include the sending cell.

[0126] Optionally, the method may further include S402, where the first cell sends sixth information to one or more cells. The sixth information may indicate the first RNA or indicate the one or more cells. Correspondingly, the one or more cells may receive the sixth information. Among them, the first cell may clarify that the one or more cells include some or all of the cells within the first RNA; for the cell that receives the sixth information, it may not perceive the first RNA through the sixth information, but only perceive the one or more cells through the sixth information. S402 is performed, for example, by the first network device that provides the first cell. Among them, if the one or more cells include the cells provided by the first network device, the first cell's sending of the sixth information to these cells may depend on the internal implementation of the first network device and is not limited. If the one or more cells include the cells provided by other network devices, the first cell may send the sixth information to the other network device, for example, through the Xn interface. Figure 4Taking an example where the one or more cells include a second cell and a third cell, and the first cell sends sixth information to the second cell and the third cell respectively. Among them, the second cell can be provided by the first network device or other network devices; the third cell can be provided by the first network device or other network devices, and the second cell and the third cell can be provided by the same network device or different network devices.

[0127] S403. The second cell sends third information to the first cell. Correspondingly, the first cell receives the third information from the second cell. Among them, the network device providing the second cell (such as the second network device) can send the third information to the network device providing the first cell (such as the first network device), and the network device providing the first cell receives the third information.

[0128] The third information can indicate that the packet numbers of the first multicast service provided by the second cell to the UE in the RRC idle state are out of sync, or indicate that the second cell does not support PDCP COUNT synchronization in the RRC idle state for the first multicast service, or indicate whether the second cell is currently providing the first multicast service to the UE in the RRC idle state. Among them, if the third information indicates that the second cell is currently providing the first multicast service to the UE in the RRC idle state, the third information can also indicate whether the second cell supports PDCP COUNT synchronization in the RRC idle state for the first multicast service. For more introductions on these contents, reference can be made to Figure 3 the embodiments shown.

[0129] Optionally, after determining the first RNA, if the first condition is met, the second cell can execute S403.

[0130] As an alternative implementation of the first condition, the first condition can include that the second cell in the first RNA starts to provide the first multicast service to the UE in the RRC idle state, and / or the second cell does not support PDCP COUNT synchronization in the RRC idle state for the first multicast service. For example, the first condition can be regarded as including a second condition and / or a third condition. The second condition includes that the second cell in the first RNA starts to provide the first multicast service to the UE in the RRC idle state, and the third condition includes that the second cell does not support PDCP COUNT synchronization in the RRC idle state for the first multicast service. Or, the first condition may not include branch conditions such as the second condition and / or the third condition, but is just a complete condition. Or, there may not be a concept of the first condition. For example, after determining the first RNA, if the second cell in the first RNA starts to provide the first multicast service to the UE in the RRC idle state, and / or the second cell does not support PDCP COUNT synchronization in the RRC idle state for the first multicast service, the second cell can execute S403. This article takes the first condition as an example for introduction.

[0131] For example, the first condition includes that the second cell within the first RNA starts to provide the first multicast service to the UE in the RRC idle state. Then, after determining the first RNA, if the second cell within the first RNA starts to provide the first multicast service to the UE in the RRC idle state, the second cell may execute S403. Or, if the second cell within the first RNA does not provide the first multicast service to the UE in the RRC idle state, the second cell may not need to execute S403. When executing S403, the content indicated by the third information may refer to the above introduction. For example, if the second cell within the first RNA starts to provide the first multicast service to the UE in the RRC idle state, the third information sent by the second cell may indicate that the second cell does not support the PDCP COUNT synchronization in the RRC idle state for the first multicast service, or indicate that the second cell currently provides the first multicast service to the UE in the RRC idle state, and indicate whether the second cell supports the PDCP COUNT synchronization in the RRC idle state for the first multicast service.

[0132] For another example, the first condition includes that the second cell within the first RNA starts to provide the first multicast service to the UE in the RRC idle state, and includes that the second cell does not support the PDCP COUNT synchronization in the RRC idle state for the first multicast service. Then, after determining the first RNA, if the second cell within the first RNA starts to provide the first multicast service to the UE in the RRC idle state, and the second cell does not support the PDCP COUNT synchronization in the RRC idle state for the first multicast service, the second cell may execute S403, and the content of the third information may refer to the above introduction. Or, if the second cell within the first RNA does not provide the first multicast service to the UE in the RRC idle state, and / or the second cell supports the PDCP COUNT synchronization in the RRC idle state for the first multicast service, the second cell may not need to execute S403.

[0133] Optionally, if the first network device and the second network device are the same network device, S402 does not need to be executed. Or, if the first cell can determine in other ways that the second cell does not support the PDCP COUNT synchronization in the RRC idle state for the first multicast service, S402 does not need to be executed either.

[0134] S404. The first cell determines the RNA corresponding to the first UE, for example, referred to as the second RNA. For example, S404 may be executed by the network device providing the first cell (such as the first network device).

[0135] For example, the second RNA does not include the second cell, and according to the foregoing, the first RNA includes the second cell. Optionally, the first cell may delete the second cell from the first RNA, and the first RNA after deleting the second cell may be the second RNA.

[0136] After determining the first RNA in the first cell, a certain cell (such as the second cell) within the first RNA starts to provide the first multicast service for UEs in the RRC idle state. If the second cell does not support PDCP COUNT synchronization in the RRC idle state for the first multicast service, the second cell needs to be deleted from the first RNA. Therefore, the first cell can delete the second cell from the first RNA to obtain the second RNA.

[0137] Optionally, the first cell may also send fifth information to K cells. The fifth information may indicate the second RNA, where K is a positive integer. Correspondingly, the K cells can receive the fifth information. The K cells include, for example, all or part of the cells within the second RNA. Among them, if the K cells include cells provided by the first network device, the first cell sending the fifth information to these cells may depend on the internal implementation of the first network device, without limitation. If the K cells include cells provided by other network devices, the first cell may send the fifth information to the other network device, for example, through the Xn interface.

[0138] S405: The first cell sends fourth information. Correspondingly, the first UE receives the fourth information. The fourth information may indicate the second RNA or indicate an updated RNA. For example, S405 may be executed by the network device providing the first cell (such as the first network device). Among them, S405 may be executed after S404, or S405 may be executed before S404, or S405 and S404 may also be executed simultaneously.

[0139] Since the RNA of the first UE has been updated, the first cell can notify the first UE of the updated RNA (the second RNA) through the fourth information, or can indicate to the UE (such as indicating the first UE or indicating UEs within the multicast group) to update the RNA of the UE.

[0140] Optionally, S405 may have different implementation manners, which are introduced by way of example below. Among them, S406 to S408 below are one optional implementation manner, and S409 is another optional implementation manner. These two implementation manners are two parallel solutions, and either one can be executed. Which solution to execute specifically can be decided by the first network device or predefined through a protocol, etc.

[0141] S406: The first cell sends a paging message. For example, S406 may be executed by the network device providing the first cell (such as the first network device).

[0142] The paging message can be used to page the first UE; alternatively, the paging message can also page a multicast group that includes UEs receiving the first multicast service. For example, the multicast group is the group corresponding to the first multicast service, and the first UE belongs to the multicast group. For example, if the RNAs corresponding to the UEs in the multicast group corresponding to the first multicast service all include the second cell, or the RNAs corresponding to these UEs are all the second RNA, the first cell can page the multicast group to uniformly update the RNAs of these UEs, without having to perform a paging process for each of these UEs individually.

[0143] Optionally, the paging message can also indicate to update the RNA, or indicate to update the RNA for the first multicast service, or indicate to update the RNA corresponding to the first multicast service, or indicate to update the RNA of the UEs receiving the first multicast service. Through the indication of the paging message, the paged UE can clearly know that this paging is for updating the RNA. Therefore, even if the paged UE initiates an RRC resume process based on this paging, it does not have to enter the RRC connected state and can continue to stay in the RRC unconnected state.

[0144] S407. The first UE sends an RRC resume request to the first cell. Correspondingly, the first cell receives the RRC resume request. For example, S407 can be executed by the first network device providing the first cell, that is, the first network device receives the RRC resume request.

[0145] Optionally, the resume cause included in the RRC resume request can indicate "RNA update" to indicate that the RRC resume request is for performing RNA update.

[0146] If the paging message is used to page the UEs performing the first multicast service, all the paged UEs can send RRC resume requests to the first cell. S407 takes one of the UEs (the first UE) as an example.

[0147] S408. The first cell sends an RRC release message to the first UE. Correspondingly, the first UE receives the RRC release message from the first cell. For example, S408 can be executed by the first network device providing the first cell, that is, the first network device sends the RRC release message.

[0148] The RRC release message can be used to release the first UE to the RRC idle state. Optionally, the RRC release message includes fourth information, and the fourth information can indicate a second RNA, so that the first UE can determine the updated RNA according to the fourth information. The fourth information indicates the second RNA. For example, one indication method is that the fourth information includes the identifier of the second RNA. The identifier of the second RNA is, for example, an RNA code or an index of the second RNA. Or, another indication method for the fourth information to indicate the second RNA is that the fourth information includes the identifier of the cell within the second RNA. For example, the fourth information may include a cell list, and the cell list includes the identifiers of all cells within the second RNA. The identifier of a cell is, for example, the ID of the cell.

[0149] If the paging message is for paging a multicast group, UEs that receive the paging message and receive the first multicast service can all send RRC resume requests to the first cell, and the first cell can also send RRC release messages to the paged UEs respectively. S407 takes one of the UEs (the first UE) as an example.

[0150] Alternatively, the RRC release message in S408 can also be replaced with an RRC resume response. For example, the first UE can also enter the RRC connected state through the RRC resume request in S407. At this time, the first cell can send an RRC resume response to the first UE without sending an RRC release message. The RRC resume response may include fourth information, and the fourth information can indicate a second RNA. For the method of indicating the second RNA, reference can be made to the above introduction.

[0151] After the first UE obtains the second RNA, if it moves to the second cell again, and the second cell is not within the RNA (the second RNA) of the first UE at this time, that is, the RNA to which the second cell belongs is not the same RNA as the second RNA, then the first UE can trigger an RNA update process, which will not be elaborated here.

[0152] S409: The first cell sends a paging message. For example, S409 can be executed by the first network device providing the first cell.

[0153] For example, the paging message may include fourth information, and the fourth information can indicate an updated RNA or indicate a second RNA. For example, in the paging message, one way for the fourth information to indicate the updated RNA is that the fourth information can indicate deleting the second cell or indicate deleting the second cell from the RNA of the UE. For how the fourth information indicates the second RNA, reference can be made to the introduction of S408.

[0154] If the fourth information indicates to delete the second cell, or indicates to delete the second cell from the UE's RNA, then the UE that receives this paging message and receives the first multicast service can determine the updated RNA of the UE according to the original RNA of the UE and the fourth information. For example, the UE that receives this paging message and receives the first multicast service can delete the second cell from the original RNA of the UE. Among them, the original RNAs of different UEs that receive this paging message and receive the first multicast service may be the same or different. Therefore, the RNAs obtained after different UEs that receive this paging message and receive the first multicast service delete the second cell from their respective RNAs may also be the same or different. For example, the RNA originally maintained by the first UE is the first RNA. After receiving this paging message, if this paging message pages the first UE, the first UE can delete the second cell from the first RNA to obtain the updated RNA (the second RNA) of the first UE; for another example, the RNA originally maintained by another UE is the third RNA. After receiving this paging message, if this paging message pages this UE, this UE can delete the second cell from the third RNA to obtain the updated RNA of this UE.

[0155] Or, if the fourth information indicates the second RNA, then the UE that receives this paging message and receives the first multicast service can determine the second RNA according to the fourth information without having to consider the original RNA of the UE. For example, if this paging message indicates the second RNA, then after the first UE receives this paging message, if this paging message pages the first UE, the first UE can delete the stored first RNA and store the second RNA; or the first UE can overwrite the stored first RNA with the second RNA.

[0156] Optionally, if this paging message indicates to delete the second cell, or indicates to delete the second cell from the UE's RNA, or indicates the second RNA, that is, if S409 is executed, the first UE may not have to execute the RRC restoration procedure (such as the procedure introduced in steps S407 - S408, etc.), but can update the RNA through the paging message in S409, which is beneficial to saving signaling overhead.

[0157] Optionally, before executing S406 - S408, or before executing S409, the paged UE has been released to the RRC idle state. For example, the first UE is released to the RRC idle state in the first cell.

[0158] Alternatively, if the foregoing S403 - S409 are not executed, that is, the second cell is not deleted from the first RNA but still exists in the first RNA, and the first UE still corresponds to the first RNA instead of the second RNA. Then, optionally, the embodiments of the present application may further include the following S410 - S411. The following third cell and the foregoing second cell may be the same cell. Or, regardless of whether the foregoing 403 - 409 are executed, the embodiments of the present application may further include the following S410 - S411. The following third cell and the foregoing second cell may be different cells.

[0159] S410. The first UE enters the third cell in the RRC idle state. For example, the first UE camps on the third cell in the RRC idle state. Among them, the steps executed by the third cell described later may be specifically executed by the network device providing the third cell, and this network device is, for example, the first network device or the second network device or other network devices.

[0160] The third cell belongs to the RNA (the first RNA) of the first UE.

[0161] S411. The first UE enters the RRC connected state in the third cell to receive the first multicast service.

[0162] For example, if the third cell does not have the ability to provide the first multicast service for the UE in the RRC idle state, or although the third cell has this ability, the third cell does not provide the first multicast service for the UE in the RRC idle state when the first UE moves to the third cell, then the first UE may enter the RRC connected state in the third cell to receive the first multicast service in the RRC connected state.

[0163] Among them, if the third cell supports PDCP COUNT synchronization in the RRC connected state for the first multicast service, the first UE may not need to reset the PDCP variable corresponding to the first multicast service. Optionally, whether to reset this PDCP variable may be determined by the third cell.

[0164] For example, if the third cell supports PDCP COUNT synchronization in the RRC connected state for the first multicast service, the third cell may not send this PDCP variable to the first UE, or may not send the value of this PDCP variable (that is, the value after the PDCP variable is reset, for example, called the updated value) to the first UE. If the first UE does not receive this PDCP variable or does not receive this updated value, it may not reset this PDCP variable. Optionally, if the first UE does not receive this PDCP variable or does not receive this updated value, it may be considered that the third cell supports PDCP COUNT synchronization in the RRC connected state for the first multicast service.

[0165] Alternatively, if the third cell does not support PDCP COUNT synchronization in the RRC connected state for the first multicast service, the first UE may reset the PDCP variables corresponding to the first multicast service. For example, if the third cell does not support PDCP COUNT synchronization in the RRC connected state for the first multicast service, the third cell may send the seventh information to the UE, and the seventh information may indicate the PDCP variables or the values of the PDCP variables (i.e., the values after the PDCP variables are reset, such as the updated values). When the first UE receives the seventh information, it may reset the PDCP variables. Optionally, when the first UE receives the updated values, it may consider that the third cell does not support PDCP COUNT synchronization in the RRC connected state for the first multicast service.

[0166] In the embodiment of the present application, there may not be too many screening conditions when initially determining the RNA, which helps to simplify the process for the network device to determine the RNA. If the cells in the RNA can achieve PDCP COUNT synchronization when providing the first multicast service in the RRC idle state, these cells may continue to be retained in the RNA; while if the cells in the RNA cannot achieve PDCP COUNT synchronization when providing the first multicast service in the RRC idle state, these cells may be deleted from the RNA. Through this subsequent screening, all the cells in the RNA can achieve PDCP COUNT synchronization when providing the first multicast service in the RRC idle state. Thus, for the UE, when moving between the cells in the RNA, the PDCP COUNT of the data packets of the first multicast service generated by these cells may be consistent, so that both the UE and these cells can keep the PDCP COUNT of the data packets of the first multicast service consistent, ensuring the normal transmission of the first multicast service. Moreover, based on the technical solution provided in the embodiment of the present application, if the cells in the RNA provide the first multicast service in the RRC idle state, the packet numbers of the data packets of the first multicast service are synchronized when providing the first multicast service in the RRC idle state, so that each cell and the UE in the RNA can have a consistent understanding of "PDCP COUNT synchronization".

[0167] Figure 5 The structural schematic diagram of a communication device provided by the embodiment of the present application is given. The communication device 500 may be Figure 3 or Figure 4 the circuit system of the first UE described in the embodiment shown, for implementing the method corresponding to the first UE in the above method embodiment. Alternatively, the communication device 500 may be Figure 3 or Figure 4The circuit system of the network device described in the illustrated embodiment is used to implement the method corresponding to the network device in the above method embodiment. The network device may include, for example, one or more of a first network device, a second network device, or other network devices. Among them, for example, a circuit system is a chip system.

[0168] The communication device 500 includes at least one processor 501. The processor 501 can be used for internal processing of the device to implement certain control processing functions. Optionally, the processor 501 includes instructions. Optionally, the processor 501 can store data. Optionally, different processors can be independent devices, can be located in different physical locations, and can be located on different integrated circuits. Optionally, different processors can be integrated in one or more processors, for example, integrated on one or more integrated circuits.

[0169] Optionally, the communication device 500 includes one or more memories 503 for storing instructions. Optionally, data can also be stored in the memory 503. The processor and the memory can be set separately or integrated together.

[0170] Optionally, the communication device 500 includes a communication line 502 and at least one communication interface 504. Among them, since the memory 503, the communication line 502, and the communication interface 504 are all optional, they are Figure 5 shown as dotted lines in the figure.

[0171] Optionally, the communication device 500 may further include a transceiver and / or an antenna. Among them, the transceiver can be used to send information to other devices or receive information from other devices. The transceiver can be called a transceiver, a transceiver circuit, an input / output interface, etc., and is used to implement the transceiver function of the communication device 500 through the antenna. Optionally, the transceiver includes a transmitter and a receiver. Exemplarily, the transmitter can be used to generate a radio frequency signal from a baseband signal, and the receiver can be used to convert a radio frequency signal into a baseband signal.

[0172] The processor 501 may include a general-purpose central processing unit (CPU), a microprocessor, an application specific integrated circuit (ASIC), or one or more integrated circuits for controlling the execution of the program of the present application solution.

[0173] The communication line 502 may include a path for transmitting information between the above components.

[0174] A communication interface 504, using any transceiver-like device, is used to communicate with other devices or communication networks, such as Ethernet, radio access network (RAN), wireless local area networks (WLAN), wired access network, etc.

[0175] The memory 503 can be a read-only memory (ROM) or other types of static storage devices that can store static information and instructions, a random access memory (RAM) or other types of dynamic storage devices that can store information and instructions, or it can also be an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compact discs, laser discs, optical discs, digital versatile discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium that can be used to carry or store the desired program code in the form of instructions or data structures and can be accessed by a computer, but not limited to this. The memory 503 can exist independently and be connected to the processor 501 through the communication line 502. Alternatively, the memory 503 can also be integrated with the processor 501.

[0176] Among them, the memory 503 is used to store computer execution instructions for implementing the solution of this application, and is controlled by the processor 501 to execute. The processor 501 is used to execute the computer execution instructions stored in the memory 503, so as to implement Figure 3 or Figure 4 the steps performed by the first UE or network device described in the embodiments shown.

[0177] Optionally, the computer execution instructions in the embodiments of this application can also be referred to as application code, and this application does not make specific limitations on this.

[0178] In a specific implementation, as an embodiment, the processor 501 can include one or more CPUs, such as Figure 5 CPU0 and CPU1 in

[0179] In a specific implementation, as an embodiment, the communication device 500 can include multiple processors, such as Figure 5The processors 501 and 505 therein. Each of these processors can be a single-CPU processor or a multi-CPU processor. The processors here can refer to one or more devices, circuits, and / or processing cores for processing data (such as computer program instructions).

[0180] When Figure 5 The device shown is a chip, such as the chip of the first UE or the chip of the network device. Then the chip includes a processor 501 (and may also include a processor 505), a communication line 502, and a communication interface 504. Optionally, it may include a memory 503. Specifically, the communication interface 504 can be an input interface, a pin, or a circuit, etc. The memory 503 can be a register, a cache, etc. The processors 501 and 505 can be a general-purpose CPU, a microprocessor, an ASIC, or one or more integrated circuits for controlling the execution of a program of any of the above communication methods.

[0181] The embodiments of the present application can divide the device into functional modules according to the above method examples. For example, each functional module can be divided corresponding to each function, or two or more functions can be integrated into one processing module. The above integrated modules can be implemented in the form of hardware or in the form of software functional modules. It should be noted that the division of modules in the embodiments of the present application is illustrative, only a logical function division, and there may be other division methods in actual implementation. For example, in the case of dividing each functional module corresponding to each function, Figure 6 It is a schematic diagram of a device. The device 600 can be the first UE or the network device involved in the above method embodiments, or the chip in the first UE or the chip in the network device. The device 600 includes a processing unit 602 and a transceiver unit 601.

[0182] It should be understood that the device 600 can be used to implement the steps executed by the first UE or the network device in the communication method of the embodiments of the present application, and the related features can be referred to the above Figure 3 or Figure 4 shown embodiments, which will not be elaborated here.

[0183] Optionally, Figure 6 the functions / implementation processes of the transceiver unit 601 and the processing unit 602 therein can be implemented by Figure 5 the processor 501 in Figure 6 calling the computer execution instructions stored in the memory 503. Or, Figure 5 the functions / implementation processes of the processing unit 602 in Figure 6The function / implementation process of the transceiver unit 601 in [text] can be implemented by Figure 5 the communication interface 504 in [text].

[0184] Optionally, when the device 600 is a chip or a circuit, the function / implementation process of the transceiver unit 601 can also be implemented by pins or circuits, etc. Optionally, the transceiver unit 601 may include a sending unit and / or a receiving unit. The sending unit is used to implement the sending function, and the receiving unit is used to implement the receiving function; or, the transceiver unit 601 may be an integrated module that can implement the sending function and / or the receiving function. Optionally, the transceiver unit 601 can be implemented by a transceiver.

[0185] This application also provides a computer-readable storage medium that stores computer programs or instructions. When the computer programs or instructions are run, the methods executed by the first UE or the network device in the foregoing method embodiments are implemented. In this way, the functions described in the above embodiments can be implemented in the form of software function units and sold or used as independent products. Based on such an understanding, the technical solution of this application, in essence, or the part that makes a contribution, or a part of this technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of this application. The storage medium includes: various media such as USB flash drives, mobile hard disks, ROM, RAM, magnetic disks, or optical discs that can store program codes.

[0186] This application also provides a computer program product that includes computer program code. When the computer program code runs on a computer, the computer is caused to execute the methods executed by the first UE or the network device in any of the foregoing method embodiments.

[0187] This application embodiment also provides a processing device, including a processor and an interface; the processor is used to execute the methods executed by the first UE or the network device involved in any of the foregoing method embodiments.

[0188] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the processes or functions described in the embodiments of the present application are generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (such as infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server or a data center that includes one or more integrated available media. The available medium can be a magnetic medium (such as a floppy disk, hard disk, magnetic tape), an optical medium (such as a DVD), or a semiconductor medium (such as a solid state disk (SSD)), etc.

[0189] In the embodiments of the present application, the various illustrative logical units and circuits described can be implemented or operated to perform the described functions by a design of a general-purpose processor, a digital signal processor (DSP), an ASIC, a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination of the above. The general-purpose processor can be a microprocessor. Optionally, the general-purpose processor can also be any conventional processor, controller, microcontroller, or state machine. The processor can also be implemented by a combination of computing devices, such as a digital signal processor and a microprocessor, multiple microprocessors, one or more microprocessors combined with a digital signal processor core, or any other similar configuration.

[0190] The steps of the methods or algorithms described in the embodiments of the present application may be directly embedded in hardware, software units executed by a processor, or a combination of the two. The software units may be stored in a RAM, flash memory, ROM, erasable programmable read-only memory (EPROM), EEPROM, register, hard disk, removable disk, CD-ROM, or any other form of storage medium in the art. Exemplarily, the storage medium may be connected to the processor so that the processor can read information from the storage medium and write information to the storage medium. Optionally, the storage medium may also be integrated into the processor. The processor and the storage medium may be provided in an ASIC, and the ASIC may be provided in a terminal device. Optionally, the processor and the storage medium may also be provided in different components of the terminal device.

[0191] These computer program instructions may also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in a process Figure 1 a process or multiple processes and / or boxes Figure 1 or steps for implementing the functions specified in multiple boxes or a box.

[0192] The content in the various embodiments of the present application may be referred to each other. If there is no special description and logical conflict, the terms and / or descriptions between different embodiments are consistent and may be cross-referred to each other. The technical features in different embodiments may be combined to form new embodiments according to their inherent logical relationships.

[0193] It can be understood that in the embodiments of the present application, the first UE and / or the network device may execute some or all of the steps in the embodiments of the present application. These steps or operations are only examples. In the embodiments of the present application, other operations or various deformations of the operations may also be executed. In addition, the various steps may be executed in different orders presented in the embodiments of the present application, and it is possible not to execute all the operations in the embodiments of the present application.

Claims

1. A communication method, characterized in that, the method includes: determining a Radio Network Area (RNA) corresponding to a first communication device, where the packet numbers of the first multicast service are synchronized when all cells within the RNA provide the first multicast service to a communication device in the Radio Resource Control (RRC) idle state; sending first information to the first communication device, where the first information is used to indicate the RNA.

2. The method according to claim 1, characterized in that, determining the RNA corresponding to the first communication device includes: acquiring information of a first cell, where the information of the first cell is used to indicate whether the packet numbers of the first multicast service are synchronized when the first cell provides the first multicast service to a communication device in the RRC idle state; determining the RNA according to the information of the first cell.

3. The method according to claim 2, characterized in that, the information of the first cell is further used to indicate whether the packet numbers of the first multicast service are synchronized when the first cell provides the first multicast service to a communication device in the RRC connected state.

4. The method according to any one of claims 1 to 3, characterized in that, when all or some cells within the RNA provide the first multicast service to a communication device in the RRC connected state, the packet numbers of the first multicast service are synchronized.

5. The method according to claim 4, characterized in that, the first information is further used to indicate that when all or some cells within the RNA provide the first multicast service to a communication device in the RRC connected state, the packet numbers of the first multicast service are synchronized.

6. The method according to any one of claims 1 to 5, characterized in that, the first information is used to indicate the RNA, including: the first information includes the identifiers of the cells within the RNA; or, the first information includes the identifier of the RNA.

7. The method according to any one of claims 1 to 6, characterized in that, the first information is included in an RRC release message, and the RRC release message is used to release the first communication device to the RRC idle state.

8. The method according to any one of claims 1 to 7, characterized in that, the method further includes: receiving a first request message from the first communication device, where the first request message is used to request to reset the Packet Data Convergence Protocol (PDCP) variables corresponding to the first multicast service or to request to enter the RRC connected state; sending second information to the first communication device, where the second information is used to indicate the PDCP variables.

9. A communication method, characterized in that, the method includes: receiving first information, where the first information is used to indicate an RNA, and the packet numbers of the first multicast service are synchronized when all cells within the RNA provide the first multicast service to a communication device in the RRC idle state.

10. The method according to claim 9, characterized in that, the method further includes: Receive the first multicast service from a first cell in the RRC idle state, where the first cell belongs to the RNA and the PDCP variables corresponding to the first multicast service remain unchanged.

11. The method according to claim 9 or 10, wherein, the first information is further used to indicate that when all or part of the cells in the RNA provide the first multicast service to a communication device in the RRC connected state, the packet numbers of the first multicast service are synchronized.

12. The method according to claim 11, wherein, the method further includes: Reside in a first cell within the RNA in the RRC idle state; If the first multicast service from the first cell is not received, enter the RRC connected state in the first cell; Receive the first multicast service in the RRC connected state, where the PDCP variables corresponding to the first multicast service remain unchanged.

13. The method according to any one of claims 9 to 12, wherein, the first information is used to indicate the RNA, including: the first information includes the identifiers of the cells within the RNA; or, the first information includes the identifier of the RNA.

14. The method according to any one of claims 9 to 13, wherein, the first information is included in an RRC release message, and the RRC release message is used to release the first communication device to the RRC idle state.

15. A communication method, wherein, the method includes: Determine a first RNA of a first communication device, where the first RNA includes a first cell and a second cell; Receive third information from the second cell, where the third information is used to indicate that the packet numbers of the first multicast service provided by the second cell to a communication device in the RRC idle state are not synchronized; Determine a second RNA of the first communication device, where the second RNA includes the first cell and does not include the second cell; Send fourth information, where the fourth information is used to indicate the second RNA.

16. The method according to claim 15, wherein, the fourth information is included in an RRC release message, and the RRC release message is used to release the first communication device to the RRC idle state.

17. The method according to claim 16, wherein, the method further includes: Send a paging message; Receive an RRC resume message from the first communication device, where the resume reason value included in the RRC resume message is used to indicate RNA update.

18. The method according to claim 17, wherein, the paging message is further used to indicate RNA update.

19. The method according to claim 15, wherein, the fourth information is included in a paging message, where the fourth information is used to indicate RNA update or indicate the second RNA.

20. The method according to any one of claims 15 to 19, wherein, the method further includes: Send fifth information to at least one cell in the second RNA, where the fifth information is used to indicate the second RNA.

21. A communication method, characterized in that the method includes: Receiving a paging message from a first cell, where the paging message is used to indicate an updated RNA or indicate a second RNA; When the paging message is used to indicate an updated RNA, determine the second RNA corresponding to the first communication device according to the paging message and the first RNA corresponding to the first communication device, where the second RNA does not include information of a second cell, and the first RNA includes information of the second cell.

22. A communication device, characterized in that the communication device includes a processing unit and a transceiver unit, and the processing unit is coupled to the transceiver unit to execute the method according to any one of claims 1 to 8, or execute the method according to any one of claims 9 to 14, or execute the method according to any one of claims 15 to 20, or execute the method according to claim 21.

23. A communication device, characterized in that the communication device includes a processor and a memory, the memory is used to store a computer program, and the processor is used to execute the computer program stored on the memory, so that the communication device executes the method according to any one of claims 1 to 8, or makes the communication device execute the method according to any one of claims 9 to 14, or makes the communication device execute the method according to any one of claims 15 to 20, or makes the communication device execute the method according to claim 21.

24. A computer-readable storage medium, characterized in that the computer-readable storage medium is used to store a computer program, and when the computer program runs on a computer, it makes the computer execute the method according to any one of claims 1 to 8, or makes the computer execute the method according to any one of claims 9 to 14, or makes the computer execute the method according to any one of claims 15 to 20, or makes the computer execute the method according to claim 21.

25. A computer program product, characterized in that the computer program product includes a computer program, and when the computer program runs on a computer, it makes the computer execute the method according to any one of claims 1 to 8, or makes the computer execute the method according to any one of claims 9 to 14, or makes the computer execute the method according to any one of claims 15 to 20, or makes the computer execute the method according to claim 21.

26. A chip system, characterized in that the chip system includes: A processor and an interface, the processor is used to call and run instructions from the interface, and when the processor executes the instructions, it implements the method according to any one of claims 1 to 8, or implements the method according to any one of claims 9 to 14, or implements the method according to any one of claims 15 to 20, or implements the method according to claim 21.

27. A communication system, characterized in that, the communication system includes a network device and a first communication device, wherein, the network device is configured to execute the method according to any one of claims 1 to 8, and the first communication device is configured to execute the method according to any one of claims 9 to 14; or, the network device is configured to execute the method according to any one of claims 15 to 20, and the first communication device is configured to execute the method according to claim 21.

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