Communication method and communication apparatus

Abstract

The present application provides a communication method and a communication apparatus. The method comprises: receiving configuration information of at least one cell in a first cell, the at least one cell including a second cell, and configuration information of the second cell comprising a multicast radio bearer (MRB) configuration for receiving a first multicast session; handing over to the second cell; upon receiving the configuration information of the at least one cell, receiving first information, the first information being used for indicating a first parameter, and the first parameter being used for determining a receiving window for an MRB of the first multicast session; and on the basis of the first information and the configuration information of the second cell, receiving the first multicast session in the second cell. According to the method, a terminal device can properly establish the MRB of the first multicast session, thereby ensuring normal transmission of multicast services between a user equipment and network devices.

Description

Communication method and communication device

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of China on December 28, 2023, with application number 202311852972.9 and invention name “Communication Method and Communication Device”, the entire contents of which are incorporated by reference into this application. Technical Field

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

[0003] In the multicast and broadcast service (MBS), MBS data is transmitted through the MBS Radio Bearer (MRB). For an MBS, the data received by terminal devices that successively join the multicast service all come from one MRB, and the Packet Data Convergence Protocol (PDCP) count (COUNT) values ​​of the data packets with the same content received by different terminal devices at different base stations that successively establish the multicast service are also consistent. This is called the PDCP COUNT synchronization mechanism of the MBS. Therefore, in order to synchronize the terminal device with the current serving cell and the core network number, the network side needs to indicate the initial PDCP COUNT value to the terminal device when creating or re-establishing the MRB.

[0004] In the L1 / L2 Triggered Mobility (LTM) mechanism, the network device pre-configures multiple candidate cells for the terminal device during the LTM preparation phase, and subsequently controls the terminal device to change between the multiple candidate cells through L1 signaling or L2 signaling. However, if the network device indicates the initial PDCP COUNT value through the candidate cell configuration during the LTM preparation phase, it may cause the receiving window of the MRB of the MBS established by the terminal device during the subsequent candidate cell handover to not match the actual receiving window, affecting the normal transmission of the terminal device and the network device. Summary of the Invention

[0005] The present application provides a communication method and a communication device, which can support the terminal device to correctly establish a multicast wireless bearer for multicast services when performing cell switching under the LTM mechanism, thereby ensuring the normal transmission of multicast services between the terminal device and the network device.

[0006] In the first aspect, a communication method is provided. The method can be executed by a terminal device, or can be executed by a component of the terminal device (such as a chip or circuit). There is no limitation on this. For the sake of ease of description, the following is explained using the execution by the terminal device as an example.

[0007] The method includes: receiving configuration information of at least one cell in a first cell, the at least one cell including a second cell, the configuration information of the second cell including a multicast radio bearer (MRB) configuration for receiving a first multicast session; switching to the second cell; after receiving the configuration information of the at least one cell, receiving first information for indicating a first parameter for determining a receiving window of the MRB for the first multicast session; and receiving the first multicast session in the second cell based on the first information and the configuration information of the second cell.

[0008] It should be understood that in the embodiments of the present application, the aforementioned multicast can be replaced by descriptions such as broadcast, groupcast, MBS, multicast service, broadcast service, or multicast service, and those skilled in the art can understand its meaning.

[0009] It should be understood that the configuration information of the at least one cell may be included in an RRC reconfiguration message.

[0010] In one possible implementation, the configuration information of the second cell may be a layer 1 / layer 2 triggered mobility (L1 / L2 Triggered Mobility, LTM) candidate cell configuration, and the configuration information of the second cell includes a reference configuration (Reference Configuration) and a candidate configuration (Candidate delta Configuration), and the embodiment of the present application does not limit the specific location of the MRB configuration.

[0011] By way of example and not limitation, the MRB configuration may be included in the reference configuration.

[0012] By way of example and not limitation, the MRB configuration may be included in the candidate delta configurations.

[0013] It should be understood that the configuration information of the second cell may also include at least one of a temporary multicast group identifier (TMGI), a group radio network temporary identifier (G-RNTI), a discontinuous reception (DRX) configuration, or a physical downlink shared channel (PDSCH) configuration. Among them, TMGI is used to identify multicast services or broadcast services. G-RNTI is used to identify the dynamic scheduling of service data. The DRX configuration is used for the terminal device to obtain the configuration of discontinuous reception, which can avoid the terminal device from always monitoring the control channel, thereby reducing the power consumption of the terminal device. The PDSCH configuration is used for the terminal device to obtain the PDSCH configuration for receiving multicast configuration information or service information.

[0014] It should be understood that the embodiment of the present application does not limit the specific number of the at least one cell.

[0015] As an example but not a limitation, the at least one cell includes only one cell, namely, the second cell.

[0016] As an example but not limitation, the at least one cell may include two cells, such as a first cell and a second cell, or a second cell and a third cell.

[0017] As an example but not limitation, the at least one cell may include three cells, such as a first cell, a second cell, and a third cell.

[0018] It should be understood that the above-mentioned first cell and the second cell may correspond to the same network device, for example, the first cell and the second cell are co-site cells, or the above-mentioned first cell and the second cell may correspond to different network devices respectively, for example, the first cell and the second cell are cross-site cells. The embodiments of the present application do not limit this.

[0019] It is easy to understand that when other cells in the at least one cell are not available for transmitting the first multicast session (for example, in a local MBS scenario, the cell is not within the service range corresponding to the first multicast session), the configuration information of the cell does not include the MRB configuration for receiving the first multicast session.

[0020] It should be understood that the difference between the first parameter and the count value of the data packets being sent by the network device in the MRB of the first multicast service at the moment when the network device sends the first information is less than the first threshold, so the terminal device can determine the correct receiving window of the MRB of the first multicast session based on the first parameter.

[0021] It should be understood that the embodiments of the present application do not limit the specific value of the first threshold. As an example and not a limitation, the first threshold is 0. As an example and not a limitation, the first threshold is the PDCP receive window size, such as 2^(PDCP-SN-Size)-1.

[0022] Based on the above solution, when the terminal device switches to the cell supporting the first multicast session, it can correctly establish the MRB of the first multicast session according to the configuration information of the second cell provided by the first network device in the LTM preparation stage and the first indication information received subsequently, thereby ensuring the normal transmission of multicast services between the user device and the network device.

[0023] In combination with the first aspect, in certain implementations of the first aspect, receiving the first multicast session in the second cell based on the first information and the configuration information of the second cell includes: establishing a first MRB based on the first information and the configuration information of the second cell; and receiving the first multicast session in the second cell based on the first MRB.

[0024] In combination with the first aspect, in certain implementations of the first aspect, the configuration information of the second cell includes a second parameter, which is used to determine the receiving window of the MRB of the first multicast session, and establishing the first MRB based on the first information and the configuration information of the second cell includes: establishing the first MRB based on the first information and the part of the configuration information of the second cell except the second parameter.

[0025] It should be understood that the receiving window for receiving the MRB determined by the terminal device according to the second parameter is the receiving window of the MRB of the first multicast session at the moment when the network device sends the configuration information of the second cell.

[0026] Exemplarily, the second parameter is an initial value of the PDCP window variable RX_DELIV.

[0027] It should be understood that the establishment of the first MRB based on the first information and the part of the configuration information of the second cell except the second parameter can be understood as that, after receiving the first information, the terminal device ignores the second parameter and uses the part of the configuration information of the second cell except the second parameter to establish the first MRB.

[0028] Based on the above scheme, when the configuration information of the second cell sent by the first network device to the terminal device during the LTM preparation phase includes a second parameter, the terminal device can ignore the second parameter when establishing the first MRB, and establish the first MRB based on the first information, thereby ensuring the normal transmission of multicast services between the user device and the network device.

[0029] In combination with the first aspect, in some implementations of the first aspect, the first information is included in a media access control MAC control element (CE), and the receiving the first information includes: receiving the first information from the first cell.

[0030] It should be understood that the first information may also be included in downlink control information (Downlink Control Information), which is not limited in this embodiment of the present application.

[0031] Based on the above scheme, the first network device can carry the first information through MAC CE, so that the terminal device can correctly establish the first MRB based on the first information and the configuration information of the second cell, thereby ensuring the normal transmission of the first multicast session between the terminal device and the network device while improving the flexibility of indicating the first information.

[0032] In combination with the first aspect, in some implementations of the first aspect, the MAC control unit is further used to instruct the terminal device to switch to the second cell.

[0033] Based on the above solution, the first network device can improve the efficiency of the terminal device in establishing the MRB of the first multicast session by carrying the first information in the MAC CE that instructs the terminal device to switch to the second cell.

[0034] In combination with the first aspect, in certain implementations of the first aspect, establishing a first MRB based on the first information and the configuration information of the second cell includes: sending the first parameter to a packet data convergence protocol PDCP entity or a radio resource control RRC entity through a MAC entity; determining the configuration information of the first MRB based on the configuration information of the second cell and the first parameter through the PDCP entity or the RRC entity; and establishing the first MRB based on the configuration information of the first MRB.

[0035] Based on the above solution, after receiving the first information carried by the MAC CE, the terminal device sends the first parameter indicated by the first information internally to the PDCP entity or the RRC entity, and determines the configuration information of the first MRB, thereby correctly establishing the first MRB.

[0036] In combination with the first aspect, in certain implementations of the first aspect, the first information is included in a wireless resource control message, and receiving the first information includes: receiving the first information from the second cell, and the method also includes: receiving second information, and the second information is used to instruct the terminal device to switch to the second cell.

[0037] It should be understood that the terminal device may receive the first information before or after the second information is received, and this embodiment of the present application does not limit this.

[0038] Based on the above scheme, the first network device can carry the first information through an RRC message, so that the terminal device can correctly establish a first MRB based on the first information and the configuration information of the second cell, thereby ensuring the normal transmission of the first multicast session between the terminal device and the network device while improving the flexibility of indicating the first information.

[0039] In combination with the first aspect, in certain implementations of the first aspect, the first parameter is an initial value of a PDCP count value of a first data packet in the MRB of the first multicast session waiting to be delivered to a protocol layer above the PDCP layer.

[0040] On the second aspect, a communication method is provided. The method can be executed by a first network device, or can also be executed by a component of the first network device (such as a chip or circuit). There is no limitation on this. For the sake of ease of description, the following is explained using the execution by the first network device as an example.

[0041] The method includes: sending configuration information of at least one cell to a terminal device in a first cell, the at least one cell including a second cell, the configuration information of the second cell including a multicast radio bearer (MRB) configuration for the terminal device to receive a first multicast session; after sending the configuration information of the at least one cell, sending first information to the terminal device or a second network device, the second network device being related to the second cell, the first information being used to indicate a first parameter, the first parameter being used to determine a receiving window of the MRB of the first multicast session; and sending the first multicast session in the second cell based on the first configuration information and the first information.

[0042] As an example but not limitation, the first network device may be a centralized unit (CU) of a network device.

[0043] It should be understood that the first network device can determine the first parameter by determining the count value of the first data packet to be delivered to the layer above the PDCP layer in the MRB of the first multicast service of the terminal device.

[0044] It should be understood that the first network device may determine the first parameter by determining a count value of the first data packet to be delivered to a layer above the PDCP layer in the MRB receiving window of the current network device itself.

[0045] It should be understood that the first network device may determine the first parameter by determining a count value of the data packet currently being sent.

[0046] It should be understood that the difference between the first parameter and the count value of the currently sent data packet is less than or equal to the first threshold, so the terminal device can determine the correct receiving window of the MRB of the first multicast session based on the first parameter.

[0047] It should be understood that the embodiments of the present application do not limit the specific value of the first threshold. As an example and not a limitation, the first threshold is 0. As an example and not a limitation, the first threshold is the PDCP receive window size, such as 2^(PDCP-SN-Size)-1.

[0048] It should be understood that after the first network device determines the first parameter, it can send the first information to the terminal device, or send the first information to the second network device so that the terminal device can indirectly obtain the first parameter.

[0049] It should be understood that the embodiment of the present application does not limit the triggering conditions for the first network device to send the first information to the second network device.

[0050] As an example but not a limitation, the first network device may periodically send the first information to the second network device.

[0051] As an example but not limitation, the first network device may send the first information based on a request from the second network device.

[0052] Based on the above scheme, the first network device can send the configuration information of the second cell to the terminal device during the LTM preparation phase, and send the first information to the terminal device or the second network device, so that the terminal device can correctly establish the MRB of the first multicast session, thereby ensuring the normal transmission of multicast services between the user device and the network device.

[0053] In combination with the second aspect, in certain implementations of the second aspect, before the configuration information of at least one cell is sent in the first cell, the method also includes: sending fourth information to the second network device, the fourth information being used to request a candidate configuration of the second cell, the candidate configuration of the second cell being used to determine the configuration information of the second cell; and receiving fifth information from the second network device, the fifth information being used to indicate the candidate configuration of the second cell.

[0054] It should be understood that the fourth information may be included in a Candidate Configuration Request message, and the fourth information may include a reference configuration.

[0055] It should be understood that the candidate configuration of the second cell may be a candidate delta configuration of the second cell.

[0056] In combination with the second aspect, in certain implementations of the second aspect, when the first information is sent to the terminal device, the first information is included in a radio resource control message.

[0057] Based on the above scheme, the first network device can carry the first information through an RRC message, so that the terminal device can correctly establish a first MRB based on the first information and the configuration information of the second cell, thereby ensuring the normal transmission of the first multicast session between the terminal device and the network device while improving the flexibility of indicating the first information.

[0058] In combination with the second aspect, in some implementations of the second aspect, when sending the first information to the second network device, before sending the first information, the method also includes: receiving sixth information from the second network device, the sixth information being used to request the first parameter.

[0059] Based on the above solution, the first network device can send the first information to the second network device in response to the request of the second network device, thereby avoiding additional communication overhead.

[0060] In combination with the second aspect, in certain implementations of the second aspect, the first parameter is an initial value of a first PDCP count value in the MRB of the first multicast session waiting to be delivered to a protocol layer above the PDCP layer.

[0061] On the third aspect, a communication method is provided. The method can be executed by a second network device, or can also be executed by a component of the second network device (such as a chip or circuit). There is no limitation on this. For the sake of ease of description, the following is explained using the execution by the second network device as an example.

[0062] The method includes: receiving first information from a first network device, the first information being used to indicate a first parameter, the first parameter being used to determine a receiving window of a first multicast session; sending the first information to a terminal device; and sending the first multicast session in the second cell, wherein the second cell is related to the second network device.

[0063] As an example but not a limitation, the second network device may be a distributed unit (CU) of a network device.

[0064] It should be understood that the second cell is related to the second network device, and it can be understood that the second cell is the cell of the second network device.

[0065] It should be understood that sending the first multicast session in the second cell can be understood as the second network device receiving the first multicast session sent by the first network device and sending the first multicast session to the terminal device in the second cell.

[0066] It should be understood that the difference between the first parameter and the count value of the currently sent data packet is less than or equal to the first threshold, so the terminal device can determine the correct receiving window of the MRB of the first multicast session based on the first parameter.

[0067] It should be understood that the embodiments of the present application do not limit the specific value of the first threshold. As an example and not a limitation, the first threshold is 0. As an example and not a limitation, the first threshold is the PDCP receive window size, such as 2^(PDCP-SN-Size)-1.

[0068] Based on the above solution, the second network device can send the first information to the terminal device after receiving the first information sent by the first network device, so that the terminal device can correctly establish the MRB of the first multicast session, thereby ensuring the normal transmission of multicast services between the user device and the network device.

[0069] In combination with the third aspect, in certain implementations of the third aspect, before receiving the first information from the first network device, the method also includes: receiving fourth information from the first network device, the fourth information being used to request candidate configuration information of the second cell, the candidate configuration information of the second cell being used to determine the configuration information of the second cell; and sending fifth information, the fifth information being used to indicate the candidate configuration of the second cell.

[0070] It should be understood that the fourth information may be included in the candidate configuration request message, and the fourth information may include a reference configuration.

[0071] It should be understood that the candidate configuration of the second cell may be a candidate delta configuration of the second cell.

[0072] In combination with the third aspect, in some implementations of the third aspect, the receiving of the first information from the first network device includes: sending sixth information to the first network device, the sixth information being used to request the first parameter; and receiving the first information from the first network device.

[0073] Based on the above solution, the first network device can send the first information to the second network device in response to the request of the second network device, thereby avoiding additional communication overhead.

[0074] In the fourth aspect, a communication method is provided. The method can be executed by a terminal device, or it can be executed by a component of the terminal device (such as a chip or circuit). There is no limitation on this. For the sake of ease of description, the following is explained as an example of execution by a terminal device.

[0075] The method includes: receiving a first multicast session through a second MRB in a first cell; receiving configuration information of at least one cell in the first cell, the at least one cell including a second cell, the configuration information of the second cell including a multicast radio bearer MRB configuration for receiving the first multicast session; switching to the second cell; and receiving the first multicast session in the second cell according to a PDCP variable of the second MRB and the configuration information of the second cell.

[0076] It should be understood that the PDCP variable is used to determine the receiving window of the MRB of the first multicast session. Exemplarily, the PDCP variable may include the initial value of the PDCP count value of the first data packet in the MRB of the first multicast session waiting to be delivered to the protocol layer above the PDCP layer.

[0077] It should be understood that the above-mentioned first cell and the second cell may correspond to the same network device, for example, the first cell and the second cell are co-site cells, or the above-mentioned first cell and the second cell may correspond to different network devices respectively, for example, the first cell and the second cell are cross-site cells. The embodiments of the present application do not limit this.

[0078] It should be understood that receiving the first multicast session in the second cell based on the PDCP variables of the second MRB and the configuration information of the second cell can be understood as: establishing the first MRB based on the PDCP variables of the second MRB and the configuration information of the second cell; and receiving the first multicast session in the second cell based on the first MRB.

[0079] It should be understood that establishing the first MRB according to the PDCP variable of the second MRB and the configuration information of the second cell can be understood as establishing the first MRB using the configuration information of the second cell and including the PDCP variable of the second MRB.

[0080] It should be understood that the first MRB and the second MRB are the same MRB for the terminal device.

[0081] Based on the above solution, when the terminal device switches between two cells supporting the first multicast session, the terminal device can correctly establish the first MRB by maintaining the PDCP variable of the second MRB and according to the configuration information of the second cell, and use the first MRB to receive the first multicast session, thereby ensuring the normal transmission of the first multicast session between the terminal device and the network device.

[0082] In combination with the fourth aspect, in certain implementations of the fourth aspect, the configuration information of the second cell includes a second parameter, which is used to determine the receiving window of the MRB of the first multicast session, and establishing the first MRB based on the first information and the configuration information of the second cell includes: establishing the first MRB based on the PDCP variable of the second MRB and the part of the configuration information of the second cell except the second parameter.

[0083] Exemplarily, the second parameter is an initial value of the PDCP window variable RX_DELIV.

[0084] Based on the above scheme, when the configuration information of the second cell sent by the first network device to the terminal device during the LTM preparation phase includes a second parameter, the terminal device can ignore the second parameter when establishing the first MRB, and maintain the PDCP variable of the second MRB to establish the first MRB, thereby ensuring the normal transmission of multicast services between the user device and the network device.

[0085] In a fifth aspect, a communication device is provided, which includes a transceiver unit and a processing unit. The transceiver unit is used to receive configuration information of at least one cell in a first cell, where the at least one cell includes a second cell, and the configuration information of the second cell includes a multicast radio bearer MRB configuration for receiving a first multicast session; the processing unit is used to switch to the second cell; the transceiver unit is also used to receive first information after receiving the configuration information of the at least one cell, where the first information is used to indicate a first parameter, and the first parameter is used to determine a receiving window for the MRB for the first multicast session; the processing unit is also used to receive the first multicast session in the second cell based on the first information and the configuration information of the second cell.

[0086] It should be understood that the fifth aspect is an implementation method on the device side corresponding to the first aspect. The supplement, explanation and beneficial effects of the first aspect are also applicable to the fifth aspect and will not be repeated here.

[0087] In a sixth aspect, a communication device is provided, which includes a transceiver unit and a processing unit. The transceiver unit is used to send configuration information of at least one cell to a terminal device in a first cell, where the at least one cell includes a second cell, and the configuration information of the second cell includes a multicast radio bearer MRB configuration for the terminal device to receive a first multicast session; the transceiver unit is also used to send first information to the terminal device or a second network device after sending the configuration information of the at least one cell, where the second network device is related to the second cell, and the first information is used to indicate a first parameter, which is used to determine a receiving window of the MRB of the first multicast session; the processing unit is used to send the first multicast session in the second cell based on the first configuration information and the first information.

[0088] It should be understood that the sixth aspect is an implementation method on the device side corresponding to the second aspect. The supplement, explanation and beneficial effects of the second aspect are also applicable to the sixth aspect and will not be repeated here.

[0089] In the seventh aspect, a communication device is provided, which includes a transceiver unit and a processing unit. The transceiver unit is used to receive first information from a first network device, where the first information is used to indicate a first parameter, and the first parameter is used to determine a receiving window of a first multicast session; the transceiver unit is also used to send the first information to a terminal device; the processing unit is used to send the first multicast session in the second cell, where the second cell is related to the second network device.

[0090] It should be understood that the seventh aspect is an implementation method on the device side corresponding to the third aspect. The supplement, explanation and beneficial effects of the third aspect are also applicable to the seventh aspect and will not be repeated here.

[0091] In the eighth aspect, a communication device is provided, which includes a transceiver unit and a processing unit. The transceiver unit is used to receive a first multicast session through a second MRB in a first cell; receive configuration information of at least one cell in the first cell, the at least one cell including a second cell, and the configuration information of the second cell includes a multicast radio bearer MRB configuration for receiving the first multicast session; the processing unit is used to switch to the second cell; the processing unit is also used to receive the first multicast session in the second cell according to the PDCP variable of the second MRB and the configuration information of the second cell.

[0092] It should be understood that the eighth aspect is an implementation method on the device side corresponding to the fourth aspect. The supplement, explanation and beneficial effects of the fourth aspect are also applicable to the eighth aspect and will not be repeated here.

[0093] In a ninth aspect, a communication device is provided, the device being configured to execute the methods provided in aspects 1 to 4 above. Specifically, the device may include units and / or modules, such as a processing unit and / or a communication unit, for executing the methods in aspects 1 to 4 and any possible implementation of aspects 1 to 4.

[0094] In one implementation, the apparatus is a terminal device. When the apparatus is a terminal device, the communication unit may be a transceiver or an input / output interface; and the processing unit may be at least one processor. Optionally, the transceiver may be a transceiver circuit. Optionally, the input / output interface may be an input / output circuit.

[0095] In another implementation, the device is a chip, chip system, or circuit used in a terminal device. When the device is a chip, chip system, or circuit used in a terminal device, the communication unit may be an input / output interface, interface circuit, output circuit, input circuit, pin, or related circuit on the chip, chip system, or circuit; the processing unit may be at least one processor, processing circuit, or logic circuit. It is understandable that when the device is a chip, chip system, or circuit used in a terminal device, the terminal device involved in the method in the first or fourth aspect and any possible implementation of the first or fourth aspect is the device.

[0096] In one implementation, the apparatus is a network device (i.e., a first network device or a second network device). When the apparatus is a network device, the communication unit may be a transceiver or an input / output interface; and the processing unit may be at least one processor. Alternatively, the transceiver may be a transceiver circuit. Alternatively, the input / output interface may be an input / output circuit.

[0097] In another implementation, the device is a chip, chip system, or circuit used in a network device. When the device is a chip, chip system, or circuit used in a terminal device, the communication unit may be an input / output interface, interface circuit, output circuit, input circuit, pin, or related circuit on the chip, chip system, or circuit; the processing unit may be at least one processor, processing circuit, or logic circuit. It is understood that when the device is a chip, chip system, or circuit used in a network device, the terminal device involved in the method in the second or third aspect, and any possible implementation of the second or third aspect, is the device.

[0098] In a tenth aspect, a communication device is provided, comprising: at least one processor, the at least one processor being coupled to at least one memory, the at least one memory being used to store computer programs or instructions, and the at least one processor being used to call and run the computer program or instructions from the at least one memory, so that the communication device executes the method in any possible implementation of the first to fourth aspects and the first to fourth aspects.

[0099] In an eleventh aspect, the present application provides a processor for executing the methods provided in the above aspects.

[0100] For the operations such as sending and acquiring / receiving involved in the processor, unless otherwise specified, or if they do not conflict with their actual functions or internal logic in the relevant descriptions, they can be understood as processor output, reception, input and other operations, and can also be understood as sending and receiving operations performed by the radio frequency circuit and antenna. This application does not limit this.

[0101] In the twelfth aspect, the present application provides a computer-readable storage medium, which stores program code for execution by a device, and the program code includes methods for executing the above-mentioned first to fourth aspects and any possible implementation of the first to fourth aspects.

[0102] In a thirteenth aspect, the present application provides a computer program product comprising instructions, which, when run on a computer, enables the computer to execute the method in the above-mentioned first to fourth aspects and any possible implementation of the first to fourth aspects.

[0103] In the fourteenth aspect, the present application also provides a chip, which is used to read the computer program stored in the memory and execute the method described in any implementation of the first to fourth aspects or the first to fourth aspects above; or, the chip includes a method for executing the method described in any implementation of the first to fourth aspects or the first to fourth aspects above.

[0104] In a fifteenth aspect, the present application further provides a chip system, which includes a processor for supporting a device to implement the method described in any of the above-mentioned aspects 1 to 4, or any of the implementations of aspects 1 to 4. In one possible design, the chip system also includes a memory for storing programs and data necessary for the device. The chip system can be composed of a chip, or it can include a chip and other discrete devices.

[0105] In the sixteenth aspect, the present application provides a communication system, including: a terminal device, used to execute the method described in the first aspect or the fourth aspect and any implementation of the first aspect or the fourth aspect; a first network device, used to execute the method described in the second aspect or any implementation of the second aspect; a second network device, used to execute the method described in the third aspect or any implementation of the third aspect.

[0106] In the seventeenth aspect, the present application provides a communication system, including a terminal device as described in the fifth aspect or the eighth aspect and any implementation of the fifth aspect or the eighth aspect, a first network device as described in the sixth aspect or any implementation of the sixth aspect, and a second network device as described in the seventh aspect or any implementation of the seventh aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0107] FIG1 is a schematic diagram of a communication system provided in an embodiment of the present application;

[0108] FIG2 is a schematic diagram of a base station architecture provided by an embodiment of the present application;

[0109] FIG3 is a schematic diagram of the MBS service transmission process;

[0110] FIG4 is a schematic diagram of a multicast service transmission process;

[0111] FIG5 is a schematic diagram of an LTM inter-cell mobility process;

[0112] FIG6 is a flow chart of the LTM preparation phase under the CU-DU separation architecture of the base station;

[0113] FIG7 is a schematic diagram of a communication method 700 proposed in an embodiment of the present application;

[0114] FIG8 is a schematic diagram of a communication process 800 proposed in an embodiment of the present application;

[0115] FIG9 is a schematic diagram of another communication process 900 provided in an embodiment of the present application;

[0116] FIG10 is a schematic block diagram of a communication device 1000 provided in this application;

[0117] FIG11 is a schematic structural diagram of the communication device 10 provided in this application. DETAILED DESCRIPTION

[0118] In order to facilitate understanding of the embodiments of the present application, the following points are first explained.

[0119] The technical solutions of the application embodiments can be applied to various communication systems, such as long term evolution (LTE), fifth generation (5G), new radio (NR), Internet of Things (IoT), wireless-fidelity (WiFi), wireless communications related to the 3rd Generation Partnership Project (3GPP), or other wireless communications that may appear in the future.

[0120] The technical solution provided in this application can also be applied to machine type communication (MTC), device-to-device (D2D) networks, machine-to-machine (M2M) networks, Internet of Things (IoT) networks or other networks.

[0121] Referring to Figure 1 , which is a schematic diagram of a communication system provided by an embodiment of the present application. The communication system includes at least one network device, such as network device 110 shown in Figure 1 ; the communication system 100 may also include at least one terminal device, such as terminal device 120 and / or terminal device 130 shown in Figure 1 . Network device 110 and terminal devices 120 / 130 may communicate via a wireless link, thereby exchanging information. It will be appreciated that network devices and terminal devices may also be referred to as communication devices.

[0122] A network device is a network-side device with wireless transceiver functions. A network device may be a device in a radio access network (RAN) that provides wireless communication functions for terminal devices, and is called a RAN device. For example, the network device may be a base station, an evolved NodeB (eNodeB), a next-generation NodeB (gNB) in a 5G mobile communication system, a base station that has been subsequently evolved by 3GPP, a transmission reception point (TRP), an access node in a WiFi system, a wireless relay node, a wireless backhaul node, etc. In communication systems using different radio access technologies (RAT), the names of devices with base station functions may be different. For example, in an LTE system, it may be called an eNB or eNodeB, and in a 5G system or NR system, it may be called a gNB. This application does not limit the specific name of the base station. The network device may include one or more co-located or non-co-located transmission and reception points.

[0123] For another example, a network device may be a centralized unit (CU) and / or a distributed unit (DU). CU and DU are different logical nodes and may be deployed on different physical devices or on the same physical device. If the control plane and user plane separation architecture is considered, the CU may be further divided into a centralized unit control plane (CU-CP) entity (or also referred to as a CU-CP node) and a centralized unit user plane (CU-UP) entity (or also referred to as a CU-UP node). Among them, the DU covers the physical layer of the baseband processing and part of the functions of the media access control (MAC) layer or the radio link control (RLC) layer. Considering the transmission resources between the radio remote unit (RRU) and the DU, some of the physical layer functions of the DU may be moved up to the RRU. With the miniaturization of the RRU, even more radical DUs may be merged with the RRU. DU deployment depends on the actual network environment. For example, in core urban areas, areas with high traffic density, small inter-station spacing, and limited equipment room resources, such as universities and large performance venues, DUs can be deployed centrally. In areas with sparse traffic and large inter-station spacing, such as suburban counties and mountainous areas, DUs can be deployed in a distributed manner. The CU encompasses the high-level protocol stack of the radio access network and some core network functions, such as the radio resource control (RRC) layer and the packet data convergence protocol (PDCP) layer. It can even support the downlink of some core network functions to the access network, which can be called an edge computing network. This can meet the higher latency requirements of future communication networks for emerging services such as video, online shopping, and virtual / augmented reality. The CU-CP is the control plane entity, encompassing the functions of the RRC and PDCP layers. It primarily manages and schedules resources for the DU and CU-UP, as well as manages and relays control plane signaling. CU-UP is a user plane entity, which currently mainly covers the PDCP layer and mainly transmits user plane traffic. It transmits data when a session arrives.

[0124] As shown in Figure 2, the gNB-CU-CP connects to the gNB-DU via the F1-C interface, and the gNB-CU-UP connects to the gNB-CU-CP via the E1 interface. A gNB-DU connects to only one gNB-CU-CP, and a gNB-CU-UP connects to only one gNB-CU-CP. The gNB-CU-CP implements gNB control plane functions, including those for the Uu, NG, and Xn interfaces. The gNB-CU-UP provides gNB user plane functions, including those for the Uu, NG, and Xn interfaces.

[0125] For another example, in vehicle to everything (V2X) technology, the network device may be a road side unit (RSU). The multiple network devices in the communication system may be base stations of the same type or different types. The base station may communicate with the terminal device or communicate with the terminal device through a relay station. In an embodiment of the present application, the device for implementing the function of the network device may be the network device itself, or a device that can support the network device to implement the function, such as a chip system or a combination device or component that can implement the function of the network device, and the device may be installed in the network device. In an embodiment of the present application, the chip system may be composed of chips, or may include chips and other discrete devices.

[0126] A terminal device is a user-side device with wireless transceiver capabilities. It can be a fixed device, mobile device, handheld device (such as a mobile phone), wearable device, in-vehicle device, or a wireless device built into any of the above devices (such as a communication module, modem, or chip system). Terminal devices are used to connect people, objects, and machines, and can be used in a wide range of scenarios, such as cellular communications, device-to-device (D2D) communications, vehicle-to-everything (V2X) communications, machine-to-machine / machine-type communications (M2M / MTC) communications, the Internet of Things (IoT), virtual reality (VR), augmented reality (AR), industrial control, self-driving, remote medical care, smart grids, smart furniture, smart offices, smart wearables, smart transportation, smart cities, drones, robots, and other scenarios. Exemplarily, the terminal device can be a handheld terminal in cellular communication, a communication device in D2D, an IoT device in MTC, a surveillance camera in intelligent transportation and smart cities, or a communication device on a drone, etc. The terminal device may sometimes be referred to as user equipment (UE), user terminal, user device, user unit, user station, terminal, access terminal, access station, UE station, remote station, mobile device or wireless communication device, etc. In the embodiment of the present application, the device for realizing the function of the terminal device may be a terminal device, or a device that can support the terminal device to realize the function, such as a chip system or a combination device or component that can realize the function of the terminal device, and the device can be installed in the terminal device. For the convenience of description, the terminal device is taken as an example for explanation in this application.

[0127] In order to facilitate understanding of the technical solution of this application, a brief introduction is given to the relevant concepts involved in the application embodiments.

[0128] 1. Multicast and broadcast service (MBS)

[0129] MBS is a service for multiple UEs, such as live broadcasts, scheduled program broadcasts, and batch software updates. From the perspective of end-to-end management and control processes and transmission methods, NR-designed MBS is divided into two categories: broadcast services and multicast services. As shown in Figure 3, MBS originates from a data server. The data server first sends the MBS data to the core network device, which then sends the MBS data to the base station. Finally, the base station sends the MBS data to at least one UE receiving the MBS. When the core network sends MBS data to the base station, it is transmitted over a common transmission channel, an MBS session. Each MBS session can contain at least one MBS Quality of Service (QoS) flow. When the base station sends MBS data to a UE, it is transmitted over an MBS radio bearer. There are two transmission modes for an MBS radio bearer: point-to-multipoint (PTM) transmission and point-to-point (PTP) transmission.

[0130] 2. Multicast service

[0131] Multicast services are designed for services with high QoS requirements and can provide the same QoS level as unicast services. Specifically, for multicast services, access network equipment and core network equipment need to maintain UE information corresponding to the multicast service group. Specifically, for multicast services, the core network needs to manage UE joining and leaving. The control signaling between the core network and the base station relies on protocol data unit (PDU) sessions, introducing a new MBS QoS flow. The base station supports both PTP and PTM methods to send data to the UE, and supports dynamic switching between PTP and PTM controlled by the base station. As shown in Figure 4, the base station can transmit the same multicast service to multiple UEs using a group radio network temporary identifier (G-RNTI), i.e., perform PTM transmission. At the same time, the base station can also allocate a corresponding cell radio network temporary identifier (C-RNTI) to each UE. The C-RNTI is used for PTP transmission when needed. Multicast services also support deactivation or activation of MBS sessions triggered by the core network, and the UE is unaware of the service status. MBS in R18 supports providing multicast services to inactive UEs, which will avoid network congestion and improve system capacity.

[0132] 3. Local MBS

[0133] The service content of local MBS services is related to the service area. They are specifically categorized into two types: local MBS services, also known as area-limited MBS services, and location-dependent MBS services. The corresponding multicast service area (MBS service area) consists of a set of tracking areas and / or cells, which indicate a specific range. For area-limited MBS services, each MBS service is associated with a multicast service area. UEs within the multicast service area can receive multicast data. When a UE moves outside the multicast service area, even if it remains within the same base station, it cannot receive data from this local MBS service. For location-dependent MBS services, each MBS service is associated with multiple multicast service areas, each identified by an Area Session ID. Different Area Session IDs for the same multicast service may have different data content and possibly different data sources. UEs are unaware of the Area Session ID, only the MBS Session ID (TMGI). The base station controls the transmission of different multicast data to different UEs within different areas.

[0134] 4. Multicast Radio Bearers (MBS radio bearers, MRB)

[0135] Network devices and terminal devices have a specific protocol stack structure for mutual communication. The user plane protocol stack structure may include the Radio Resource Control (RRC) layer, the Service Data Adaptation Protocol (SDAP) layer, the Packet Data Convergence Protocol (PDCP) layer, the Radio Link Control (RLC) layer, the Media Access Control (MAC) layer, and the physical (PHY) layer. The physical layer is located at the lowest layer (Layer 1), while the MAC, RLC, PDCP, and SDAP layers belong to the second layer (Layer 2), and the RRC layer belongs to the third layer (Layer 3). For the user plane protocol stack of MBS transmission (for MBS services, the transmission direction is from the base station to the UE), data first arrives at the base station's SDAP layer. After being mapped by the SDAP layer, it is transmitted to the corresponding PDCP entity. After being processed by the base station's PDCP layer, it is transmitted to the RLC and MAC layers. After the corresponding processing, it is sent from the physical layer and transmitted to the UE side via the air interface. The various protocol layers on the UE then process the data packets in the reverse order of the base station's processing. The processing of data packets by each layer on the base station and UE can be figuratively referred to as radio bearers (RBs). Each data item in a radio bearer is processed by each layer, and each layer has a corresponding functional entity to perform its function. Each radio bearer configuration includes a PDCP entity, and each radio bearer configuration is associated with at least one RLC entity, and each RLC entity corresponds to a logical channel.

[0136] It should be understood that the protocol stack structure described above is only an example and should not constitute a limitation. There may be fewer or more layers, or the functions of some layers may be merged into one layer, or the structure may be changed. This application does not limit this.

[0137] For MBS, user plane data is carried by MRB. Specifically, MRB includes the following three types: a separate PTP MRB (PTP only MRB), a separate PTM MRB (PTM only MRB), and a split MRB, wherein the split MRB includes PTP MRB and PTM MRB. Among them, the PTP only MRB is associated with a PTP RLC entity, the PTM only MRB is associated with a PTM RLC entity, and the split MRB is associated with a PTM RLC entity and a PTP RLC entity. Among them, the PTM RLC is the same for multiple UEs, and the multiple UEs use the same G-RNTI to monitor the PDCCH. The PTP RLC is independent for each UE, and each UE uses its own C-RNTI to monitor the PDCCH.

[0138] It should be understood that one MBS session corresponds to one or more MRBs, that is, one service may correspond to one or more MRBs.

[0139] It should also be understood that one MRB corresponds to only one G-RNTI, but one G-RNTI may correspond to multiple MRBs, and one G-RNTI corresponds to multiple MRBs which may be MRBs for the same service or not.

[0140] 5. L1 / L2 Triggered Mobility

[0141] Traditional inter-cell mobility management is typically based on Layer 3 measurements and triggered by RRC signaling. Layer 1 / L2 Triggered Mobility extends the concept of intra-cell Layer 1 beam management to inter-cell mobility management, instructing terminals to perform cell handovers through Layer 1 measurements and reporting, as well as Layer 1 / L2 signaling.

[0142] For example, in a 5G system, the network side may provide the terminal with multiple "candidate cells (candidate cell groups)". In some embodiments, the network side may subsequently control the terminal to change among multiple "candidate cells (candidate cell groups)" through L1 signaling (e.g., downlink control information (DCI)) or L2 signaling (e.g., MAC control element (MAC CE)). For example, the working cell (cell group) is changed from "candidate cell (candidate cell group)-1" to "candidate cell (candidate cell group)-2". Among them, one serving cell (serving cell group) may correspond to one or more "candidate cells (candidate cell groups)".

[0143] As shown in FIG5 , the inter-cell mobility process based on layer 1 / layer 2 signaling can be specifically divided into the following four stages: (1) LTM preparation stage: in steps 510 to 520, the base station prepares the candidate cell and sends it to the UE in the RRC connected state through an RRC message in step S530; (2) Early synchronization: including steps S540a and S540b, in which the UE performs downlink synchronization to the candidate cell in step S540a and in which the UE performs uplink synchronization to the candidate cell in step S540b, for example, through the Physical Downlink Control Channel (PDCCH) command of the early random access channel (RACH) or the timing advance (TA) acquisition based on the UE; (3) LTM cell switch execution stage: including steps S550 to S570, in which the UE sends an L1 measurement report to the base station in step S550 and the base station sends an LTM MAC to the UE in step S560. CE, triggering cell switching. In step S570, if the uplink early synchronization in step S540b has been completed, RACH can be skipped. Otherwise, RACH is initiated. (4) LTM cell switch completion: In step S580, the UE sends an RRC Reconfiguration Complete message to the base station to complete the cell switching process.

[0144] The following describes the specific process of the LTM preparation phase under the CU-DU separation architecture of the base station with reference to FIG6:

[0145] S610: The CU initiates LTM, for example, by determining LTM candidate cells and candidate DUs through L3 measurement results.

[0146] S620: The CU sends a candidate configuration request message to the candidate DU (C-DU). The candidate configuration request message is used to request the candidate DU to provide a candidate configuration. The candidate configuration may include a primary cell (PCell) configuration and a secondary cell (SCell) configuration. In addition, the candidate configuration may also include an L1 measurement and reporting configuration.

[0147] S630: The candidate DU sends a candidate Delta configuration to the CU in response to the candidate configuration request message.

[0148] At step S640, the CU sends a candidate pre-configuration message to the UE via a service DU (S-DU). The candidate pre-configuration message includes a reference configuration and a candidate delta configuration. Traditional incremental configuration is based on a specific source cell configuration. However, in subsequent LTM handovers, since the UE can perform continuous handovers based on the instructions of the MAC CE, any cell can be the source cell during the cell handover process. Therefore, the traditional incremental configuration process is no longer applicable, and thus a reference configuration is introduced.

[0149] Based on the above steps, the UE may generate a complete candidate configuration using the reference configuration and the candidate delta configuration.

[0150] 6. Multicast service PDCP processing

[0151] The PDCP Protocol Data Unit (PDU) data identifier / count value (Count) consists of the high-order Hyperframe Number (HFN) and the low-order PDCP Sequence Number (SN). Only the PDCP SN is added to the PDU for transmission, while the HFN is maintained by the transmitter and receiver. In other words, the PDCP PDU sent by the transmitter to the receiver contains the SN number, but not the COUNT or HFN. The receiver calculates the HFN and restores the COUNT value.

[0152] When establishing an existing unicast Data Radio Bearer (DRB), the protocol stipulates that the HFN does not interact over the air interface, and both the network and the UE start from 0. This ensures that the HFN on the UE and network sides are consistent. However, unlike the DRB operation of a unicast session, an MRB (for example, an MRB used by a connected UE to receive multicast services) is shared by multiple UEs. UEs that successively join a multicast service receive data from the same MRB, and the PDCP COUNT values ​​for data packets with the same content received by different UEs at different base stations that successively establish a multicast service are also consistent. This is called the PDCP COUNT synchronization mechanism of MBS. Therefore, in order to enable both the UE and the current base station, as well as different base stations, to achieve PDCP COUNT synchronization, the standard defines that different base stations generate PDCP COUNT values ​​based on the numbers of the same data packets sent by the core network. When the base station creates or reestablishes an MRB for the UE, the base station needs to indicate to the UE the initial PDCP COUNT value corresponding to the MRB (the specific value can be the PDCP window variable RX_DELIV, which is the COUNT value of the first PDCP SDU in the PDCP entity that has not been submitted to the upper layer but is still waiting to be submitted. It is the lower bound of the PDCP receive window, which is used by the receiving end to determine the HFN part based on the SN of the received PDCP SDU). The specific configuration information element is:

[0153] initialRX-DELIV-r17 BIT STRING(SIZE(32))OPTIONAL--Cond MRB-Initialization

[0154] However, while the above-mentioned MRB configuration introduces the initialRX-DELIV field to solve the PDCP count value synchronization problem, it also brings new problems. In the LTM scenario, the candidate cell configuration will be sent to the UE in advance by the CU. The initialRX-DELIV field included in the candidate cell configuration indicates the value of the PDCP receive window variable at the time of configuration. It is easy to understand that as the transmission between the base station and the UE proceeds, the PDCP receive window will also change. If the UE uses the initialRX-DELIV field in the candidate cell configuration to establish an MRB when performing cell switching based on MAC CE or DCI indication, an incorrect MRB or an inaccurate MRB will be established, affecting the normal transmission of the UE and the base station.

[0155] For example, during the LTM preparation phase, the network device configures the initial value of the PDCP count value for the UE as 1+1000 (where the number before the plus sign is the HFN and the number after the plus sign is the SN). Subsequently, the UE continues to receive data packets in cell 1, and the lower bound of its receive window is updated to 3+50. At this time, the UE is handed over from cell 1 to cell 2. If the UE reconfigures the initial value of the PDCP count value to 1+1000 according to the LTM candidate cell configuration after handing over to cell 2, the PDCP COUNT value of the newly received data packet with an SN of 55 may be determined to be 0+55. In other words, the UE incorrectly identifies that the number of the data packet is outside the receive window, resulting in packet loss.

[0156] In view of this, the embodiments of the present application propose a communication method and a communication device, which can support LTM for MRB multicast switching, thereby ensuring normal transmission between UE and base station.

[0157] To facilitate understanding of the embodiments of the present application, the following points are explained:

[0158] First, in this application, unless otherwise specified or there is a logical conflict, the terms and / or descriptions between different embodiments are consistent and can be referenced by each other. The technical features in different embodiments can be combined to form new embodiments based on their internal logical relationships.

[0159] Second, in this application, "at least one" means one or more, and "more" 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 can mean: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. In the text description of this application, the character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b and c can mean: a, or b, or c, or a and b, or a and c, or b and c, or a, b and c. Wherein a, b and c can be single or multiple, respectively.

[0160] Third, throughout this application, the terms "first," "second," and various numerical references (e.g., #1, #2, etc.) are used to distinguish between different messages for ease of description and are not intended to limit the scope of the embodiments of this application. For example, they are used to distinguish between different messages, rather than to describe a specific order or precedence. It should be understood that the terms described in this manner are interchangeable where appropriate to describe scenarios beyond the embodiments of this application.

[0161] Fourth, in this application, the terms "comprise" and "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or are inherent to these processes, methods, products or apparatuses.

[0162] Fifth, in this application, "used to indicate" can include being used for direct indication and being used for indirect indication. When describing that a certain indication information indicates A, it can include that the indication information directly indicates A or indirectly indicates A, and it does not mean that the indication information must carry A.

[0163] The indication methods involved in the embodiments of this application should be understood to encompass various methods that enable the party to be indicated to obtain information to be indicated. The information to be indicated can be sent as a whole or divided into multiple sub-information and sent separately. The transmission period and / or timing of these sub-information can be the same or different. This application does not limit the specific transmission method.

[0164] In the embodiments of the present application, the "indication information" may be an explicit indication, i.e., a direct indication via signaling, or may be obtained based on parameters indicated by the signaling, in combination with other rules, other parameters, or by deduction. It may also be an implicit indication, i.e., based on a rule or relationship, or based on other parameters, or by deduction. This application does not impose specific limitations on this.

[0165] Sixth, in this application, "protocol" may refer to a standard protocol in the field of communications, such as the 5G protocol, the NR protocol, and related protocols used in future communication systems, and this application does not limit this. "Predefined" may include pre-definition. For example, protocol definition. "Preconfiguration" can be implemented by pre-saving corresponding codes, tables, or other methods that can be used to indicate relevant information in the device, and this application does not limit its specific implementation method.

[0166] Seventh, in this application, "storage" may refer to storage in one or more memories. The one or more memories may be separate or integrated into an encoder or decoder, a processor, or a communication device. The one or more memories may also be partially separate and partially integrated into a decoder, a processor, or a communication device. The memory may be any type of storage medium and is not limited in this application.

[0167] Eighth, in this application, if there is no logical conflict, "report", "feedback" and "send" can be interchanged.

[0168] FIG7 is a schematic diagram of a communication method 700 proposed in an embodiment of the present application. As shown in the figure, the method 700 includes the following steps:

[0169] S710, the first network device sends configuration information of at least one cell to the terminal device, and correspondingly, the terminal device receives the configuration information of the at least one cell.

[0170] The configuration information of the at least one cell includes the configuration information of the second cell, wherein the configuration information of the second cell includes an MRB configuration for receiving the first multicast session, so that the terminal device can use the MRB configuration to receive the first multicast session.

[0171] It should be understood that in the embodiments of the present application, the aforementioned multicast can be replaced by descriptions such as broadcast, groupcast, MBS, multicast service, broadcast service, or multicast service, and those skilled in the art can understand its meaning.

[0172] It should be understood that the configuration information of the at least one cell may be included in an RRC reconfiguration message.

[0173] In one possible implementation, the configuration information of the second cell may be an LTM candidate cell configuration. Optionally, the configuration information of the second cell includes a reference configuration and a candidate configuration. The embodiment of the present application does not limit the specific location of the MRB configuration.

[0174] By way of example and not limitation, the MRB configuration may be included in the reference configuration.

[0175] By way of example and not limitation, the MRB configuration may be included in the candidate delta configurations.

[0176] It should be understood that the configuration information of the second cell may also include at least one of a temporary multicast group identifier (TMGI), a group radio network temporary identifier (G-RNTI), a discontinuous reception (DRX) configuration, or a physical downlink shared channel (PDSCH) configuration. Among them, TMGI is used to identify multicast services or broadcast services. G-RNTI is used to identify the dynamic scheduling of service data. The DRX configuration is used for the terminal device to obtain the configuration for discontinuous reception, which can avoid the terminal device from always monitoring the control channel, thereby reducing the power consumption of the terminal device. The PDSCH configuration is used for the terminal device to obtain the PDSCH configuration for receiving multicast configuration information or service information.

[0177] It should be understood that the embodiment of the present application does not limit the specific number of the at least one cell.

[0178] As an example but not a limitation, the at least one cell includes only one cell, namely, the second cell.

[0179] As an example but not limitation, the at least one cell may include two cells, such as a first cell and a second cell, or a second cell and a third cell.

[0180] As an example but not limitation, the at least one cell may include three cells, such as a first cell, a second cell, and a third cell.

[0181] It should be understood that the above-mentioned first cell and the second cell may correspond to the same network device, for example, the first cell and the second cell are co-site cells, or the above-mentioned first cell and the second cell may correspond to different network devices respectively, for example, the first cell and the second cell are cross-site cells. The embodiments of the present application do not limit this.

[0182] It is easy to understand that when other cells in the at least one cell are not available for transmitting the first multicast session (for example, in a local MBS scenario, the cell is not within the service range corresponding to the first multicast session), the configuration information of the cell does not include the MRB configuration for receiving the first multicast session.

[0183] In a possible implementation, the configuration information of the second cell may further include a second parameter, which is used to determine the receiving window of the MRB of the first multicast session. Exemplarily, the second parameter is an initial value of a PDCP window variable RX_DELIV.

[0184] It should be understood that the receiving window for receiving the MRB determined according to the second parameter is the receiving window at the time of executing step S710. The specific usage of the second parameter will be described later and will not be repeated here.

[0185] It should be understood that before the above step S710, the method 700 further includes the above steps (not shown in the figure):

[0186] S701: A first network device sends fourth information to a second network device. Correspondingly, the second network device receives the fourth information.

[0187] The fourth information is used to request a candidate configuration of the second cell, and the candidate configuration of the second cell is used to determine configuration information of the second cell.

[0188] Optionally, the fourth information includes the candidate configuration request message in the aforementioned step S640, and the third information includes a reference configuration.

[0189] S702: The second network device sends a candidate configuration of the second cell to the first network device. Correspondingly, the first network device receives the candidate configuration of the second cell.

[0190] Based on the above steps S701 and S702, the first network device may determine the configuration information of the second cell.

[0191] S720: The first network device sends first information, where the first information is used to indicate a first parameter, and the first parameter is used to determine a receiving window of an MRB of the first multicast session.

[0192] It should be understood that the embodiment of the present application does not limit the specific manner in which the first network device determines the first parameter.

[0193] As an example but not limitation, the first network device may determine the first parameter by determining a count value of the first data packet to be delivered to a layer above the PDCP layer in the MRB of the first multicast session of the terminal device.

[0194] As an example but not a limitation, the first network device may determine the first parameter by determining a count value of the first data packet to be delivered to a layer above the PDCP layer in the MRB receiving window of the current network device itself.

[0195] As an example and not a limitation, the first network device may determine the first parameter by determining a value of a currently transmitted data packet (hereinafter referred to as value #1).

[0196] It should be understood that the first multicast session can be transmitted through one or more MRBs. When determining the first parameter, the first network device needs to determine the corresponding first parameter for each MRB of the first multicast session. The following is an example of establishing an MRB by a terminal device.

[0197] It should be understood that the manner in which the first network device determines the first parameter corresponding to each MRB may be the same or different, and this embodiment of the present application does not limit this.

[0198] It should be understood that the difference between the first parameter and the value #1 is less than or equal to the first threshold, wherein the embodiment of the present application does not limit the specific numerical value of the first threshold.

[0199] As an example and not a limitation, the first threshold is 0.

[0200] As an example but not limitation, the first threshold is the PDCP receiving window size, such as 2^(PDCP-SN-Size)-1.

[0201] It should be understood that after the first network device determines the first parameter, it can indicate the first parameter to the terminal device or the second network device by sending the first information. The following is an example of the first network device sending the first information to the terminal device or the second network device.

[0202] Method 1: The first network device sends the first information to the terminal device:

[0203] It should be understood that in this implementation, the method 700 further includes the following steps (not shown in the figure):

[0204] S715. The second network device sends second information to the terminal device. Correspondingly, the terminal device receives the second information.

[0205] The second information is used to instruct the terminal device to switch to the second cell, and the second information is optionally included in the MAC CE or downlink control information (Downlink Control information, DCI).

[0206] Furthermore, the terminal device switches from the first cell to the second cell according to the second information.

[0207] It should be understood that the above step S715 can be performed before step S720, or the above step S715 can be performed after step S720, and this embodiment of the present application does not limit this.

[0208] It should be understood that after receiving the above-mentioned first information, the terminal device can internally send the first parameter from the MAC entity to the PDCP entity, or the terminal device can internally send the first parameter from the MAC entity to the RRC entity to generate the configuration information of the first MRB, and then establish the first MRB based on the configuration information of the first MRB.

[0209] In one possible implementation, the second cell configuration information received by the terminal device in step S710 includes the second parameter. In establishing the first MRB based on the second cell configuration information, the terminal device may establish the first MRB based on the portion of the second cell configuration information excluding the second parameter. Alternatively, after receiving the first information, the terminal device ignores the second parameter in the second cell configuration information and establishes the first MRB based on the first information.

[0210] Based on the above steps, after switching to the second cell, the terminal device can establish a first MRB based on the configuration information of the second cell received in step S710 and the first information received in step S720, and receive the first multicast session through the first MRB.

[0211] Method 2: The first network device sends the first information to the second network device:

[0212] It should be understood that the embodiment of the present application does not limit the triggering conditions for the first network device to send the first information to the second network device.

[0213] As an example but not a limitation, the first network device may periodically send the first information to the second network device.

[0214] As an example but not limitation, the first network device may send the first information based on a request from the second network device.

[0215] Specifically, the second network device may send sixth information to the first network device, where the sixth information is used to request the first parameter. Correspondingly, the first network device may send the first information to the second network device based on the fifth information.

[0216] It should be understood that, in this implementation, the method 700 further includes the following steps:

[0217] S720b, the second network device sends the first information to the terminal device, and correspondingly, the terminal device receives the first information.

[0218] It should be understood that the first information may be included in a MAC CE or a DCI, that is, the second network device may send the first information to the terminal device via a MAC CE or a DCI.

[0219] In a possible implementation, the second network device may carry the first information in a MAC CE or DCI that instructs the terminal device to switch to the second cell.

[0220] In another possible implementation, the second network device may send the first information to the terminal device through a separate MAC CE in addition to the MAC CE or DCI that instructs the terminal device to switch to the second cell.

[0221] Similarly, after receiving the above-mentioned first information, the terminal device can internally send the first parameter from the MAC entity to the PDCP entity, or the terminal device can internally send the first parameter from the MAC entity to the RRC entity to generate the configuration information of the first MRB, and then establish the first MRB based on the configuration information of the first MRB.

[0222] Based on the above steps, after switching to the second cell, the terminal device can establish a first MRB based on the configuration information of the second cell received in step S710 and the first information received in step S720b, and receive the first multicast session through the first MRB.

[0223] S730: The terminal device transmits a first multicast session with the first network device and the second network device.

[0224] Specifically, the first network device may send the first multicast session to the second network device based on the configuration information of the second cell and the first parameter. After receiving the first multicast session, the second network device forwards the first multicast session to the terminal device, and the terminal device uses the first MRB to receive the first multicast session.

[0225] Based on the above solution, when the terminal device switches to a cell that supports the first multicast session, the terminal device can correctly establish a first MRB based on the pre-configured configuration information of the second cell and the first information sent by the first network device or the second network device, and use the first MRB to receive the first multicast session, thereby ensuring the normal transmission of the first multicast session between the terminal device and the network device.

[0226] Optionally, when the first cell supports the first multicast session, the first network device or the second network device may not need to send the first information to the terminal device. Correspondingly, the terminal device maintains the PDCP state variable (such as RX_DELIV) of the current MRB of the first multicast session (i.e., the MRB of the first multicast session established by the terminal device in the first cell, hereinafter referred to as the second MRB) during the process of establishing the first MRB.

[0227] Specifically, if the configuration information of the second cell includes the second parameter, the terminal device ignores the second parameter and maintains the PDCP state variable (such as RX_DELIV) of the second MRB, and uses the configuration information of the second cell to establish the first MRB; if the configuration information of the second cell does not include the second parameter, the terminal device maintains the initial value of the PDCP count value of the second MRB and uses the configuration information of the second cell to establish the first MRB. It can be understood that the first MRB and the second MRB are the same MRB for the terminal device.

[0228] Based on the above solution, when the terminal device switches between two cells supporting the first multicast session, the first network device or the second network device may not need to send the first information to the terminal device. The terminal device can correctly establish the first MRB by maintaining the initial value of the PDCP count value of the second MRB and according to the configuration information of the second cell, and use the first MRB to receive the first multicast session, thereby ensuring the normal transmission of the first multicast session between the terminal device and the network device.

[0229] Optionally, the configuration information of the at least one cell in step S710 also includes configuration information of a third cell, and the third cell does not support the first multicast session (for example, in a local MBS scenario, the third cell is not within the service area of ​​the first multicast reply). The method 700 may further include the following steps (not shown in the figure):

[0230] S740: The second network device sends third information to the terminal device, and correspondingly, the terminal device receives the third information.

[0231] The third information is used to instruct the terminal device to switch to a third cell, and the configuration information of the third cell includes the configuration information of at least one cell received by the terminal device in step S710.

[0232] S750, the terminal device switches to the third cell according to the third information and the configuration information of the third cell.

[0233] It should be understood that when the terminal device switches to the third cell, the terminal device releases the above-mentioned second MRB.

[0234] The following describes the specific process of method 700 shown in FIG. 7 through the interaction between UE (ie, terminal equipment) and a cell in conjunction with FIG. 8 and FIG. 9 .

[0235] FIG8 is a schematic diagram of a communication process 800 proposed in an embodiment of the present application. As shown in the figure, the process 800 includes the following steps:

[0236] S810. Cell 1 sends configuration information of at least one cell to the UE. Correspondingly, the UE receives the configuration information of the at least one cell.

[0237] The configuration information of the at least one cell includes configuration information of cell 2 and configuration information of cell 3. For detailed description of the cell configuration information, please refer to the relevant content of step S710 and will not be repeated here.

[0238] It should be understood that the configuration information of each cell supporting a multicast session includes an MRB configuration, so that the UE can create or re-establish an MRB according to the MRB configuration to receive the corresponding multicast service. In addition, the specific location of the MRB configuration is not limited in the embodiment of the present application.

[0239] In a possible implementation, the configuration information of the at least one cell may further include configuration information of the UE's current serving cell (ie, cell 1).

[0240] It should be understood that the above-mentioned cell 1, cell 2 and cell 3 correspond to the same network device, for example, the above-mentioned cell 1, cell 2 and cell 3 are co-site cells.

[0241] It should be understood that at least two of the above-mentioned cells 1, 2 and 3 correspond to different network devices, for example, cell 1 and cell 2 are co-site cells, and cell 2 and cell 3 are cross-site cells.

[0242] In this embodiment of the present application, cell 1 and cell 2 support the same multicast session #1, while cell 3 does not support multicast session #1. For example, in a local MBS scenario, cell 1 and cell 2 are both within the service area of ​​multicast session #1, while cell 3 is outside the service area of ​​multicast service #1. In other words, the service area of ​​multicast service #1 includes at least one cell, including cell 1 and cell 2, and excluding cell 3.

[0243] It should be noted that in process 800, the configuration information of each cell does not include the initialRX-DELIV field of the session corresponding to multicast session #1, that is, the network device does not configure the initialRX-DELIV field for the UE in the configuration information of each cell to indicate the initial value of the PDCP window variable RX_DELIV of the MRB of the multicast session #1.

[0244] S820 , the UE receives service data of multicast session # 1 in cell 1 .

[0245] It should be understood that in the local MBS scenario, the embodiment of the present application does not limit whether the UE is aware of the service scope of multicast session #1.

[0246] As an example and not a limitation, the UE may obtain the service range information of the multicast session #1 through an application layer message. For example, the UE may obtain the service area information of the multicast session #1 through a user service description (USD) message of the multicast session #1, or the UE may obtain the service area information of the multicast session #1 through a service announcement of the multicast session #1.

[0247] S830: Cell 1 sends indication information #1 to the UE, and the UE receives the indication information #1. The indication information #1 is used to instruct the UE to switch to cell 3.

[0248] It should be understood that the indication information #1 can be MAC CE or DCI.

[0249] S840, the UE switches to cell 3 according to the indication information #1.

[0250] Specifically, in response to the indication information #1, the UE uses the configuration information of cell 3 obtained in step S810 to switch to cell 3.

[0251] It should be understood that since cell 3 does not support multicast session #1, the UE needs to release the MRB for receiving multicast session #1 established in the first cell when switching to cell 3.

[0252] It should be understood that if cell 3 does not support any multicast session, the RRC configuration without MRB configuration is effective for the UE in cell 3.

[0253] S850: Cell 3 sends indication information #2 to the UE, and the UE receives the indication information #2. The indication information #2 is used to instruct the UE to switch to cell 2.

[0254] It should be understood that the indication information #2 can be MAC CE or DCI.

[0255] S860: The UE switches to cell 2 according to the indication information #2.

[0256] Specifically, in response to the indication information #2, the UE uses the configuration information of cell 2 acquired in step S810 to switch to cell 2.

[0257] In one possible implementation, indication information #2 (an example of the first information in this implementation) is further used to indicate a first parameter, where the first parameter is used to determine a receive window for the MRB of multicast session #1. The UE may then establish MRB #1 (an example of the first MRB) based on the MRB configuration in the configuration information of cell 2 and indication information #2.

[0258] It should be understood that before cell 2 sends indication information #2 to the UE, cell 2 needs to determine the first parameter. The embodiment of the present application does not limit the specific method for cell 2 to determine the first parameter. The specific method can be referred to the relevant content of step S720 and will not be repeated here.

[0259] Exemplarily, the PDCP entity of the network device to which cell 2 belongs or the node for processing the PDCP entity sends the count value (hereinafter referred to as value #2) of the first data packet in the MRB of the multicast session #1 to be delivered to the layer above the PDCP layer to the MAC entity of the base station to which cell 2 belongs or the entity for processing the MAC entity.

[0260] Exemplarily, the gNB-CU of the network device to which cell 2 belongs sends the value #2 to the gNB-DU corresponding to cell 2.

[0261] In this embodiment of the present application, the triggering condition for the gNB-CU to send the value #2 to the gNB-DU is not limited.

[0262] In one example, the gNB-CU may periodically send the value #2 to the gNB-DU.

[0263] In another example, the gNB-CU may send the value #2 to the gNB-DU based on the gNB-DU's request.

[0264] It should be understood that the difference between the first parameter and the count value of the data packet being sent by the network device is less than or equal to the first threshold, wherein the embodiment of the present application does not limit the specific value of the first threshold.

[0265] As an example and not a limitation, the first threshold is 0.

[0266] As an example but not limitation, the first threshold is the PDCP receiving window size, such as 2^(PDCP-SN-Size)-1.

[0267] Correspondingly, when the UE receives the indication information #2, the first parameter is sent from the MAC entity to the PDCP entity within the UE, or the first parameter is sent from the MAC entity to the RRC entity within the UE, thereby generating complete configuration information of MRB#1.

[0268] Through the above steps, the UE can receive the data of the multicast session #1 on the MRB#1, and the data packet number of the first multicast session #1 received by the UE through the MRB#1 corresponds to the first parameter.

[0269] In another possible implementation, the UE establishes MRB#1 according to the MRB configuration in the configuration information of cell 2.

[0270] It should be understood that in this implementation, since the initial value of the PDCP count value of the MRB for the corresponding multicast session is mandatory when a new MRB is created, that is, the lack of this PDCP COUTN value will result in synchronization failure. Therefore, since the configuration information of cell 2 pre-configured by the network device for the UE does not include the initial value of the PDCP count value of the MRB for multicast session #1, the UE can establish a partial MRB #1 based on the MRB configuration included in the configuration information of cell 2, which can also be understood as establishing an incomplete MRB #1.

[0271] Specifically, in this implementation, the process 800 further includes the following steps (not shown in the figure):

[0272] S861, cell 2 sends indication information #3 (another example of the first information) to the UE, and correspondingly, the UE receives the indication information #3.

[0273] It should be understood that the indication information #3 is used to indicate a first parameter, and the first parameter is used to determine the receiving window of the MRB of the multicast session #1.

[0274] It should be understood that the indication information #3 may be RRC layer signaling, such as an RRC reconfiguration message.

[0275] Furthermore, the UE can determine the complete configuration information of the MRB#1 established based on the indication information #3 and the configuration information of cell 2, thereby establishing a complete, accurate or synchronized MRB#1, so that the UE can receive the multicast session #1 from cell 2 on the MRB.

[0276] In another possible implementation, after switching to cell 2, the UE ignores the MRB configuration in the configuration information of cell 2 and waits for the network device to indicate the complete configuration information of MRB#1.

[0277] It should be understood that the complete configuration of the MRB#1 refers to the configuration including the initial value of the PDCP count, and the complete MRB refers to the MRB that can achieve PDCP synchronization.

[0278] Furthermore, in this implementation, the process 800 further includes the following steps:

[0279] S862: Cell 2 sends indication information #4 (another example of the first information) to the UE, and the UE receives the indication information #4. The indication information #4 is used to indicate the complete configuration information of the MRB #1.

[0280] It should be understood that the indication information #4 includes a third parameter, which is used to determine the receiving window of the MRB of the multicast session #1. The specific method for determining the third parameter by cell 2 can refer to the method for determining the first parameter, which is not repeated here.

[0281] It should be understood that the indication information #4 may be RRC layer signaling, such as an RRC reconfiguration message.

[0282] Furthermore, the UE may establish MRB#1 according to the indication information #4, so that the UE may receive multicast session #1 from cell 2 on the MRB#1.

[0283] Based on the above scheme, the network device does not include the second parameter for indicating the initial value of the PDCP count value (e.g., PDCP window variable RX_DELIV) of the MRB for multicast session #1 in the LTM candidate cell configuration pre-configured for the user equipment, and indicates the first parameter for determining the receiving window of the MRB for multicast session #1 through additional information when the user equipment switches to the cell supporting the multicast session #1, so that the user equipment can correctly establish, reconstruct, or process the MRB, thereby ensuring the normal transmission of the multicast service data between the user equipment and the network equipment.

[0284] FIG9 is a schematic diagram of another communication process 900 provided in an embodiment of the present application. As shown in FIG9 , the process 900 includes the following steps:

[0285] S910 , cell 1 sends configuration information of at least one cell to the UE, and correspondingly, the UE receives the configuration information of the at least one cell.

[0286] For detailed description of the configuration information of each cell and detailed description of cell 1, cell 2 and cell 3, please refer to the relevant content of step S810, which will not be described in detail here.

[0287] It should be noted that in the embodiment of process 900, the configuration information of each cell includes the initialRX-DELIV field of the MRB of multicast session #1, that is, the network device configures the initialRX-DELIV field for the UE in the configuration information of each cell to indicate the initial value of the PDCP window variable RX_DELIV corresponding to the multicast session #1 (hereinafter referred to as the second parameter).

[0288] It is easy to understand that the initial value of the PDCP count value indicated by the above-mentioned initialRX-DELIV field can be the packet number, the previous packet number, or the next packet number of the PDCP data packet currently being sent by the MRB of the multicast session #1 at the moment when the network device sends the configuration information of the at least one cell, also known as the PDCP sending progress.

[0289] S920 , the UE receives service data of multicast session # 1 in cell 1 .

[0290] The specific description of step S920 can refer to the relevant content of step S820 and will not be repeated here.

[0291] S930: Cell 1 sends indication information #5 to the UE, and the UE receives the indication information #5. The indication information #5 is used to instruct the UE to switch to cell 2.

[0292] It should be understood that the indication information #5 can be MAC CE or DCI.

[0293] S940, the UE switches to cell 2 according to the indication information #5.

[0294] Specifically, in response to the indication information #5, the UE uses the configuration information of cell 2 acquired in step S910 to switch to cell 2.

[0295] It should be understood that, since the cell 2 supports the multicast session #1, the UE can also establish MRB #2 (another example of the first MRB) of the multicast session #1 in the cell 2.

[0296] It should be understood that when establishing MRB#2, since the second parameter indicated by the initialRX-DELIV field contained in the configuration information of cell 2 has expired, if the UE resets the PDCP variable according to the second parameter, it will cause the data packets of multicast session #1 received by the UE to be abnormal, affecting normal transmission.

[0297] In the embodiment of the present application, the UE can correctly establish the MRB#2 in the following manner:

[0298] In one possible implementation, the UE may ignore the second parameter in the configuration information of the cell 2 when establishing the MRB#2, or in other words, the UE may maintain the PDCP variable of the MRB#3 of the multicast session #1 established in the cell 1 when establishing the MRB#2.

[0299] It should be understood that in this implementation, since both Cell 1 and Cell 2 are within the service range of multicast session #1, and the UE receives service data for multicast session #1 in Cell 1 using MRB #3 in step S920, the UE is able to locally determine the PDCP variables of the MRB for multicast session #1. Therefore, the UE can maintain the PDCP variables of MRB #3 and correctly establish MRB #2 based on the configuration information of Cell 2. It should be understood that MRB #2 and the second MRB #3 are the same MRB for the terminal device.

[0300] In another possible implementation, the network device may indicate the PDCP state variable (e.g., RX_DELIV) of the MRB of multicast session #1 through additional information. Specifically, cell 1 may include the PDCP state variable (e.g., RX_DELIV) of multicast session #1 in indication information #5, so that the UE can correctly establish the configuration information of cell 2 based on indication information #5 and the configuration information of cell 2.

[0301] Based on the above solution, when the UE switches between cells within the service range of multicast session #1, the MRB can be correctly established to ensure that the UE can normally receive data of the multicast session #1.

[0302] S950 , cell 2 sends indication information # 6 to the UE, and the UE receives the indication information # 6 , wherein the indication information # 6 is used to instruct the UE to switch to cell 3 .

[0303] It should be understood that the indication information #6 can be MAC CE or DCI.

[0304] S960, the UE switches to cell 3 according to the indication information #6.

[0305] Specifically, in response to the indication information #6, the UE uses the configuration information of cell 3 obtained in step S910 to switch to cell 3.

[0306] It should be understood that since cell 3 does not support multicast session #1, the UE needs to release the MRB for receiving multicast session #1 established in the first cell when switching to cell 3.

[0307] It should be understood that if cell 3 does not support any multicast session, the RRC configuration without MRB configuration is effective for the UE in cell 3.

[0308] S970: Cell 3 sends indication information #7 to the UE, and the UE receives the indication information #7. The indication information #7 is used to instruct the UE to switch to cell 2.

[0309] It should be understood that the indication information #7 can be MAC CE or DCI.

[0310] S980, the UE switches to cell 2 according to the indication information #7.

[0311] Specifically, in response to the indication information #7, the UE uses the configuration information of cell 2 acquired in step S810 to switch to cell 2.

[0312] In one possible implementation, indication information #7 (an example of the first information in this implementation) is further used to indicate a first parameter, which is used to determine the receive window of the MRB for multicast session #1. The UE can then establish MRB #4 (another example of the first MRB) based on the MRB configuration in the configuration information of cell 2 and indication information #2.

[0313] It should be understood that before cell 2 sends indication information #7 to the UE, cell 2 needs to determine the first parameter of the multicast session #1. The embodiment of the present application does not limit the specific method for cell 2 to determine the above-mentioned first parameter. The specific method can be referred to the relevant content of step S860 and will not be repeated here.

[0314] Correspondingly, when the UE receives the indication information #7, the first parameter is sent from the MAC entity to the PDCP entity within the UE, or the first parameter is sent from the MAC entity to the RRC entity within the UE, thereby generating complete configuration information of MRB#4.

[0315] Through the above steps, the UE can receive the multicast session #1 on the MRB #4, and the data packet number of the first multicast session #1 received by the UE through the MRB #4 corresponds to the first parameter.

[0316] In another possible implementation, the UE establishes MRB#4 based on the configuration information of cell 2. The initial value of the PDCP count value of MRB#4 corresponds to the second parameter.

[0317] It should be noted that, in this implementation, after establishing MRB #4, the UE does not use MRB #4 to receive service data of multicast session #1 in cell 2, but waits for the network device to indicate the initial value of the PDCP count value of the MRB of multicast session #1. That is, the process 900 further includes the following steps:

[0318] S981, cell 2 sends indication information #8 (another example of the first information) to the UE, and correspondingly, the UE receives the indication information #8.

[0319] It should be understood that the indication information #8 is used to indicate the above-mentioned first parameter, so that the UE can determine the receiving window of the MRB of the multicast session #1 according to the first parameter.

[0320] Furthermore, after receiving the indication information #8, the UE may update the PDCP variable of MRB#4 according to the first parameter, so that the UE may correctly receive the data of the multicast session #1 in cell 2 through the MRB#4.

[0321] In another possible implementation, after switching to cell 2, the UE ignores the MRB configuration in the configuration information of cell 2 and waits for the network device to indicate the complete configuration information of MRB#4.

[0322] It should be understood that the complete configuration of the MRB#4 refers to the configuration including the initial value of the PDCP count, and the complete MRB refers to the MRB that can achieve PDCP synchronization.

[0323] Furthermore, in this implementation, the process 900 further includes the following steps:

[0324] S982: Cell 2 sends indication information #9 to the UE, and the UE receives the indication information #9. The indication information #9 is used to indicate the complete configuration information of the MRB #4.

[0325] It should be understood that the indication information #9 includes a third parameter, which is used to determine the receiving window of the MRB of the multicast session #1. The specific method for determining the third parameter by cell 2 can refer to the method for determining the first parameter described in step S720, and is not repeated here.

[0326] It should be understood that the indication information #9 may be RRC layer signaling, such as an RRC reconfiguration message.

[0327] Furthermore, the UE may establish MRB #4 according to the indication information #9, so that the UE may receive the multicast session #1 from the cell 2 on the MRB.

[0328] Based on the above solution, the network device includes a second parameter for indicating the initial value of the PDCP count value (e.g., PDCP window variable RX_DELIV) of the MRB for multicast session #1 in the LTM candidate cell configuration preconfigured for the user equipment, and indicates the first parameter for determining the receive window of the MRB for multicast session #1 through additional information when the user equipment switches to a cell supporting multicast session #1. Alternatively, when the user equipment switches to an inter-cell handover supporting multicast session #1, the second parameter can be ignored and the correct MRB can be established. This allows the user equipment to correctly establish, reconstruct, or process the MRB, thereby ensuring normal transmission of the multicast service data between the user equipment and the network device.

[0329] The method provided in the embodiments of the present application is described in detail above with reference to Figures 7 to 9 . The method is primarily described from the perspective of interaction between a terminal device and a network device. It is understood that, in order to implement the aforementioned functions, the terminal device and the network device include hardware structures and / or software modules that perform the respective functions.

[0330] Those skilled in the art should be aware that, in combination with the units and algorithm steps of each example described in the embodiments disclosed herein, the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is performed in the form of hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0331] Hereinafter, the communication device provided by the embodiment of the present application will be described in detail with reference to Figures 10 and 11. It should be understood that the description of the device embodiment corresponds to the description of the method embodiment. Therefore, for the content not described in detail, please refer to the method embodiment above. For the sake of brevity, some content will not be repeated. In the embodiment of the present application, the terminal device or network device can be divided into functional modules according to the above method example. 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-mentioned integrated module 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 embodiment of the present application is schematic and is only a logical functional division. There may be other division methods in actual implementation. The following is an example of dividing each functional module corresponding to each function.

[0332] Refer to FIG10 , which is a schematic block diagram of a communication device 1000 provided in this application.

[0333] In one possible design, a communication device 1000 includes a receiving unit 1100 and a processing unit 1200. The communication device 1000 can implement steps or processes corresponding to those performed by a terminal device in the above method embodiments. For example, the communication device 1000 can be a terminal device, or a chip or circuit configured in a terminal device. The receiving unit 1100 is used to perform the reception-related operations of the terminal device in the above method embodiments, and the processing unit 1200 is used to perform the processing-related operations of the terminal device in the above method embodiments.

[0334] In one possible implementation, a receiving unit 1100 is configured to receive configuration information of at least one cell in a first cell, where the at least one cell includes a second cell, and the configuration information of the second cell includes a multicast radio bearer (MRB) configuration for receiving a first multicast session. A processing unit 1200 is configured to switch to the second cell. The receiving unit 1100 is further configured to receive first information after receiving the configuration information of the at least one cell, where the first information is used to indicate a first parameter, and the first parameter is used to determine a receiving window for the MRB for the first multicast session. The processing unit 1200 is further configured to receive the first multicast session in the second cell based on the first information and the configuration information of the second cell.

[0335] In a possible implementation, the processing unit 1200 is further configured to establish a first MRB according to the first information and the configuration information of the second cell. The receiving unit 1100 is further configured to receive the first multicast session in the second cell according to the first MRB.

[0336] In one possible implementation, the configuration information of the second cell includes a second parameter, which is used to determine the receiving window of the MRB of the first multicast session. The processing unit 1200 is also used to establish the first MRB based on the first information and the part of the configuration information of the second cell except the second parameter.

[0337] In one possible implementation, the first configuration information also includes configuration information of a third cell, the at least one cell does not include the third cell, and the receiving unit 1100 is further configured to receive third information, where the third information is used to instruct the terminal device to switch to the third cell. The processing unit 1200 is further configured to release the first MRB based on the third information and the configuration information of the third cell.

[0338] Optionally, the communication device 1000 further includes a sending unit 1300. The sending unit 1300 and the receiving unit 1100 may also be integrated into a transceiver unit having both receiving and sending functions, which is not limited here.

[0339] Optionally, in an implementation where the communication device 1000 is a terminal device in a method embodiment, the sending unit 1300 may be a transmitter, and the receiving unit 1100 may be a receiver. The receiver and transmitter may also be integrated into a transceiver. The processing unit 1200 may be a processing device.

[0340] The functions of the processing device can be implemented by hardware or by executing corresponding software implementations through hardware. For example, the processing device may include a memory and a processor, wherein the memory is used to store computer programs, and the processor reads and executes the computer programs stored in the memory, so that the communication device 1000 performs the operations and / or processes performed by the terminal device in each method embodiment. Alternatively, the processing device may include only a processor, and the memory for storing the computer program is located outside the processing device. The processor is connected to the memory via circuits / wires to read and execute the computer program stored in the memory. For another example, the processing device may be a chip or an integrated circuit.

[0341] Alternatively, in an implementation where the communication device 1000 is a chip or integrated circuit installed in a terminal device, the transmitting unit 1300 and the receiving unit 1100 may be communication interfaces or interface circuits, for example, the transmitting unit 1300 is an output interface or output circuit, and the receiving unit 1100 is an input interface or input circuit. The processing unit 1200 may be a processor or microprocessor integrated on the chip or integrated circuit. This is not limited herein.

[0342] In another possible design, the communication device 1000 includes a processing unit 1200 and a sending unit 1300. The communication device 1000 can implement steps or processes corresponding to those performed by the network device in the above method embodiments. For example, the communication device 1000 can be a network device, or a chip or circuit configured in a network device. The processing unit 1200 is configured to perform the processing-related operations of the network device in the above method embodiments. The sending unit 1300 is configured to perform the receiving-related operations of the network device in the above method embodiments.

[0343] Specifically, in one possible design, the communication device can be used to implement the steps or processes executed by the first network device in the above method embodiment.

[0344] In one possible implementation, the sending unit 1300 sends configuration information of at least one cell to a terminal device in a first cell, where the at least one cell includes a second cell, and the configuration information of the second cell includes a multicast radio bearer (MRB) configuration for the terminal device to receive a first multicast session. The sending unit 1300 is further configured to, after sending the configuration information of the at least one cell, send first information to the terminal device or a second network device, where the second network device is related to the second cell, and the first information is used to indicate a first parameter, where the first parameter is used to determine a receiving window for the MRB of the first multicast session. The processing unit 1200 is further configured to send the first multicast session in the second cell based on the first configuration information and the first information.

[0345] Optionally, the apparatus 1000 further includes a receiving unit 1100. The receiving unit 1100 is configured to perform the reception-related operations of the network device in the above method embodiment. The sending unit 1300 is further configured to send fourth information to the second network device, the fourth information being used to request a candidate configuration for the second cell, the candidate configuration for the second cell being used to determine configuration information of the second cell. The receiving unit 1100 is configured to receive fifth information from the second network device, the fifth information being used to indicate a candidate configuration for the second cell.

[0346] In a possible implementation, the receiving unit 1100 is further configured to receive sixth information from the second network device, where the sixth information is used to request the first parameter.

[0347] In another possible design, the communication device can be used to implement the steps or processes performed by the second network device in the above method embodiment.

[0348] In one possible implementation, a receiving unit 1100 is configured to receive first information from a first network device, the first information indicating a first parameter used to determine a receive window for a first multicast session. A sending unit 1300 is configured to send the first information to a terminal device. The sending unit 1300 is further configured to send the first multicast session in the second cell, where the second cell is associated with the second network device.

[0349] In one possible implementation, the receiving unit 1100 is further configured to receive fourth information from the first network device, the fourth information being used to request candidate configuration information of the second cell, the candidate configuration information of the second cell being used to determine the configuration information of the second cell. The sending unit 1300 is further configured to send fifth information, the fifth information being used to indicate the candidate configuration of the second cell.

[0350] In a possible implementation, the sending unit 1300 is further configured to send sixth information to the first network device, where the sixth information is used to request the first parameter.

[0351] Optionally, the sending unit 1300 and the receiving unit 1100 may also be integrated into a transceiver unit, which has both receiving and sending functions, which is not limited here.

[0352] Optionally, in an implementation where the communication device 1000 is a network device in a method embodiment, the sending unit 1300 may be a transmitter, and the receiving unit 1100 may be a receiver. The receiver and transmitter may also be integrated into a transceiver. The processing unit 1200 may be a processing device.

[0353] The functions of the processing device can be implemented by hardware or by executing corresponding software implementations through hardware. For example, the processing device may include a memory and a processor, wherein the memory is used to store computer programs, and the processor reads and executes the computer programs stored in the memory, so that the communication device 1000 performs the operations and / or processes performed by the network device in each method embodiment. Alternatively, the processing device may include only a processor, and the memory for storing computer programs is located outside the processing device. The processor is connected to the memory via circuits / wires to read and execute the computer programs stored in the memory. For another example, the processing device may be a chip or an integrated circuit.

[0354] Alternatively, in an implementation where the communication device 1000 is a chip or integrated circuit installed in a network device, the transmitting unit 1300 and the receiving unit 1100 may be communication interfaces or interface circuits. For example, the transmitting unit 1300 may be an output interface or output circuit, and the receiving unit 1100 may be an input interface or input circuit. The processing unit 1200 may be a processor or microprocessor integrated on the chip or integrated circuit. This is not limited herein.

[0355] Referring to Figure 11, Figure 11 is a schematic structural diagram of a communication device 10 provided in this application. The device 10 includes a processor 11, which is coupled to a memory 12. The memory 12 is used to store computer programs or instructions and / or data. The processor 11 is used to execute the computer programs or instructions stored in the memory 12, or read the data stored in the memory 12, to perform the methods in the above method embodiments.

[0356] Optionally, there are one or more processors 11.

[0357] Optionally, there are one or more memories 12 .

[0358] Optionally, the memory 12 is integrated with the processor 11 or provided separately.

[0359] Optionally, as shown in Figure 11, the device 10 further includes a transceiver 13, which is used to receive and / or send signals. For example, the processor 11 is used to control the transceiver 13 to receive and / or send signals.

[0360] As a solution, the apparatus 10 is used to implement the operations performed by the terminal device in each of the above method embodiments.

[0361] For example, the processor 11 is configured to execute computer programs or instructions stored in the memory 12 to implement the operations performed by the terminal device in the above various method embodiments, for example, the methods performed by the terminal device in the embodiments shown in Figures 7 to 9.

[0362] As another solution, the apparatus 10 is used to implement the operations performed by the network device in the above various method embodiments.

[0363] For example, the processor 11 is configured to execute computer programs or instructions stored in the memory 12 to implement the operations performed by the network device in the above various method embodiments, for example, to implement the methods performed by the network device in the embodiments shown in FIG. 7 to FIG. 9 .

[0364] In addition, the present application also provides a computer-readable storage medium, which stores computer instructions. When the computer instructions are run on a computer, the operations and / or processes performed by the terminal device or network device in each method embodiment of the present application are executed.

[0365] The present application also provides a computer program product, which includes computer program code or instructions. When the computer program code or instructions are run on a computer, the operations and / or processes performed by the terminal device or network device in the various method embodiments of the present application are executed.

[0366] In addition, the present application further provides a chip, the chip including a processor. A memory for storing a computer program is provided independently of the chip, and the processor is configured to execute the computer program stored in the memory, so that the operations and / or processing performed by the terminal device or the network device in any one of the method embodiments are performed.

[0367] Furthermore, the chip may further include a communication interface. The communication interface may be an input / output interface, or an interface circuit, etc. Furthermore, the chip may further include a memory.

[0368] In addition, the present application also provides a communication system, including the terminal device and network device in the embodiments of the present application.

[0369] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0370] It should be understood that the processor in the embodiments of the present application can be an integrated circuit chip with the ability to process signals. During implementation, each step of the above method embodiment can be completed by hardware integrated logic circuits in the processor or instructions in the form of software. The processor can be a central processing unit (CPU), or it can be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor. The steps of the method disclosed in the embodiments of the present application can be directly embodied as being executed by a hardware coding processor, or can be executed by a combination of hardware and software modules in the coding processor. The software module can be located in a storage medium mature in the art, such as random access memory, flash memory, read-only memory, programmable read-only memory or electrically erasable programmable memory, registers, etc. The storage medium is located in the memory, and the processor reads the information in the memory and completes the steps of the above method in combination with its hardware.

[0371] The memory in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of RAM are available, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct rambus RAM (DRRAM).

[0372] It should be noted that when the processor is a general-purpose processor, DSP, ASIC, FPGA or other programmable logic device, discrete gate or transistor logic device, discrete hardware component, the memory (storage module) can be integrated into the processor.

[0373] It should also be noted that the memory described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0374] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0375] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0376] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0377] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the 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 enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0378] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A communication method, applied to a terminal device, characterized in that, Comprising: Receiving configuration information of at least one cell in a first cell, the at least one cell including a second cell, and the configuration information of the second cell including a Multicast Radio Bearer (MRB) configuration for receiving a first multicast session; Switching to the second cell; After receiving the configuration information of the at least one cell, receiving first information for indicating a first parameter, where the first parameter is used to determine a reception window of the MRB for the first multicast session; Receiving the first multicast session in the second cell according to the first information and the configuration information of the second cell.

2. The method according to claim 1, characterized in that, The receiving the first multicast session in the second cell according to the first information and the configuration information of the second cell includes: Establishing a first MRB according to the first information and the configuration information of the second cell; Receiving the first multicast session in the second cell according to the first MRB.

3. The method according to claim 2, wherein The configuration information of the second cell includes a second parameter for determining the reception window of the MRB for the first multicast session, and The establishing a first MRB according to the first information and the configuration information of the second cell includes: Establishing the first MRB according to the part of the first information and the configuration information of the second cell excluding the second parameter.

4. The method according to claim 2 or 3, characterized in that, The first information is included in a Media Access Control (MAC) control element, and the receiving the first information includes: receiving the first information from the first cell.

5. The method according to claim 4, characterized in that, The MAC control element is further used to instruct the terminal device to switch to the second cell.

6. The method according to claim 4 or 5, characterized in that, The establishing a first MRB according to the first information and the configuration information of the second cell includes: Sending the first parameter to a Packet Data Convergence Protocol (PDCP) entity or a Radio Resource Control (RRC) entity through a MAC entity; Determining configuration information of the first MRB according to the configuration information of the second cell and the first parameter by the PDCP entity or the RRC entity; Establishing the first MRB according to the configuration information of the first MRB.

7. The method according to claim 2 or 3, characterized in that, The first information is included in an RRC message, the receiving the first information includes: receiving the first information from the second cell, and the method further includes: Receiving second information for instructing the terminal device to switch to the second cell.

8. The method according to any one of claims 2 to 7, characterized in that The at least one cell includes a third cell, and the configuration information of the third cell does not include an MRB configuration for receiving the first multicast session. The method further includes: Receiving third information for instructing the terminal device to switch to the third cell; Releasing the first MRB according to the third information and the configuration information of the third cell.

9. The method according to any one of claims 1 to 8, characterized in that The first parameter is an initial value of a PDCP count value of the first data packet in the MRB of the first multicast session that waits to be delivered to a protocol layer above the PDCP layer.

10. A communication method, applied to a first network device, characterized in that, Comprising: Send configuration information of at least one cell to a terminal device, where the at least one cell includes a second cell, and the configuration information of the second cell includes a multicast radio bearer (MRB) configuration for the terminal device to receive a first multicast session; After sending the configuration information of the at least one cell, send first information to the terminal device or a second network device, where the second network device is related to the second cell, and the first information is used to indicate a first parameter, and the first parameter is used to determine a reception window of the MRB of the first multicast session; Send the first multicast session in the second cell based on the first configuration information and the first information.

11. The method according to claim 10, wherein Before sending the configuration information of the at least one cell in the first cell, the method further includes: Send fourth information to the second network device, where the fourth information is used to request a candidate configuration of the second cell, and the candidate configuration of the second cell is used to determine the configuration information of the second cell; Receive fifth information from the second network device, where the fifth information is used to indicate the candidate configuration of the second cell.

12. The method according to claim 10 or 11, characterized in that When sending the first information to the terminal device, the first information is included in a radio resource control message.

13. The method according to claim 10 or 11, characterized in that When sending the first information to the second network device, before sending the first information, the method further includes: Receive sixth information from the second network device, where the sixth information is used to request the first parameter.

14. The method according to any one of claims 10 to 13, characterized in that, The first parameter is an initial value of a PDCP count value of the first PDCP packet waiting to be delivered to a protocol layer above the PDCP layer in the MRB of the first multicast session.

15. A communication method, applied to a second network device, characterized in that, Includes: Receive first information from a first network device, where the first information is used to indicate a first parameter, and the first parameter is used to determine a reception window of a first multicast session; Send the first information to a terminal device; Send the first multicast session in the second cell, where the second cell is related to the second network device.

16. The method according to claim 15, wherein Before receiving the first information from the first network device, the method further includes: Receive fourth information from the first network device, where the fourth information is used to request candidate configuration information of the second cell, and the candidate configuration information of the second cell is used to determine the configuration information of the second cell; Send fifth information, where the fifth information is used to indicate the candidate configuration of the second cell.

17. The method according to claim 15 or 16, characterized in that, The receiving the first information from the first network device includes: Send sixth information to the first network device, where the sixth information is used to request the first parameter; Receive the first information from the first network device.

18. A communication method, applied to a terminal device, characterized in that, Includes: Receive a first multicast session in a first cell through a second MRB; Receive configuration information of at least one cell in the first cell, where the at least one cell includes a second cell, and the configuration information of the second cell includes a multicast radio bearer (MRB) configuration for receiving the first multicast session; Switch to the second cell; Receive the first multicast session in the second cell according to a packet data convergence protocol (PDCP) variable of the second MRB and the configuration information of the second cell.

19. The method according to claim 18, wherein The configuration information of the second cell includes a second parameter, which is used to determine the reception window of the MRB of the first multicast session, and, establishing a first MRB according to the first information and the configuration information of the second cell includes: establishing the first MRB according to the PDCP variables of the second MRB and the part of the configuration information of the second cell except the second parameter.

20. A communication device, characterized in that, for implementing the method according to any one of claims 1 to 9, or for implementing the method according to any one of claims 10 to 14, or for implementing the method according to any one of claims 15 to 17, or for implementing the method according to claim 18 or 19.

21. A communication device, characterized in that, comprising a processor, the processor being configured to, by executing a computer program or instruction, or by means of a logic circuit, cause the communication device to execute the method according to any one of claims 1 to 9, or, cause the communication device to execute the method according to any one of claims 10 to 14, or cause the communication device to execute the method according to any one of claims 15 to 17, or cause the communication device to execute the method according to claim 18 or 19.

22. The device according to claim 21, characterized in that, The communication device further includes a memory for storing the computer program or instruction.

23. The device according to claim 21 or 22, characterized in that, The communication device further includes a communication interface for inputting and / or outputting signals.

24. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions, and when the computer instructions are run on a computer, the method according to any one of claims 1 to 9 is executed, or the method according to any one of claims 10 to 14 is executed, or the method according to any one of claims 15 to 17 is executed, or the method according to claim 18 or 19 is executed.

25. A computer program product, characterized in that, The computer program product includes computer program code, and when the computer program code is run on a computer, the method according to any one of claims 1 to 9 is executed, or the method according to any one of claims 10 to 14 is executed, or the method according to any one of claims 15 to 17 is executed, or the method according to claim 18 or 19 is executed.

26. A communication system, characterized in that, comprising a terminal device, a first network device and a second network device, wherein, the terminal device is configured to execute the method according to any one of claims 1 to 9, or to execute the method according to claim 18 or 19; the first network device is configured to execute the method according to any one of claims 10 to 14; the second network device is configured to execute the method according to any one of claims 15 to 17.

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