Communication method and communication apparatus

Abstract

A communication method and a communication apparatus are provided. The method is applied to an LTM switching scenario. The method includes: A first node sends a first message to a second node, where the first message is used to request to add the second node as a candidate secondary node of a terminal, the first message includes first identification information, and the first identification information is used to request an early synchronization configuration from the second node; and the first node receives a second message from the second node, where the second message is used to acknowledge addition of the second node as the candidate secondary node of the terminal, the second message includes a first early synchronization configuration, and the first early synchronization configuration corresponds to the first identification information. In this method, the terminal implements cross-node cell switching based on early synchronization, thereby reducing switching latency.

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 February 7, 2024, with application number 202410176151.6 and invention name “A 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 fifth-generation (5G) communication technology, the movement of a terminal triggers cell switching. For example, before the signal quality of the terminal's serving cell deteriorates or even fails to communicate normally, the terminal can switch to a neighboring cell with better signal quality, thereby providing continuous communication services.

[0004] In the 5G wireless access network (RAN) architecture, a base station includes a distributed unit (DU) and a central unit (CU). For example, in layer 1 / layer 2 triggered mobility (LTM) switching, a terminal supports moving from one DU under the same CU to another DU to complete cell switching within the base station, which can avoid service drops or interruptions caused by deterioration in the signal quality of the terminal's serving cell. However, the current LTM switching scenario does not involve a solution for cell switching of the terminal between base stations. Summary of the Invention

[0005] The present application provides a communication method and a communication device, which enable a terminal to implement cell switching between base stations in an LTM switching scenario and reduce switching delay.

[0006] In a first aspect, a communication method is provided. The method is executed by a first node, or may be executed by other entities, and this application does not limit this. For ease of description, the following is an example of execution by the first node. The first node may be a network device in a dual-connectivity (DC) scenario, such as a master node (MN), or a chip or circuit in the MN, or a functional module in the MN that can call and execute a program. The method is applied to an LTM switching scenario.

[0007] The method includes: sending a first message to the second node, the first message is used to request that the second node be added as a candidate auxiliary node of the terminal, the first message includes first identification information, and the first identification information is used to request early synchronization configuration from the second node; receiving a second message from the second node, the second message is used to confirm that the second node is added as a candidate auxiliary node of the terminal, the second message includes a first early synchronization configuration, and the first early synchronization configuration corresponds to the first identification information.

[0008] According to the above solution, the first node sends the first identification information to the second node to obtain the first advance synchronization configuration, so that the terminal and the second node achieve advance synchronization in the LTM handover scenario. In this case, the terminal in the dual-connection scenario is connected to the first node and the second node respectively, and the terminal has completed the advance synchronization process with the second node before receiving the cell handover command. Subsequently, after receiving the cell handover command, the terminal can access the second node in a random access-free manner, reducing the terminal's primary and secondary cell handover delay, avoiding service drops or interruptions, and ensuring the user's service experience.

[0009] It should be understood that advance synchronization refers to a synchronization process performed by the terminal before receiving a handover command.

[0010] Exemplarily, the first early synchronization configuration includes a random access preamble index and / or a random access time-frequency resource. It should be understood that the first early synchronization configuration is a configuration of a first cell, the first cell belongs to the second node, the first cell is a candidate primary and secondary cell accepted by the second node, and the first early synchronization configuration is used to indicate a random access resource. The terminal can use the random access resource to complete early synchronization of the first cell, and after subsequently receiving a handover command, access the first cell in a manner that avoids random access.

[0011] It should be understood that the first early synchronization configuration corresponds to the first identification information, which can be understood as: the first identification information is used to request the second node to provide the early synchronization configuration, and the second node provides the first early synchronization configuration of the first cell to the first node based on the first identification information, that is, early synchronization of the first cell can be performed according to the first early synchronization configuration.

[0012] In certain implementations of the first aspect, sending a first message to a second node includes: receiving a third message from a third node, the third message including an identifier of the second node and first identifier information, the third node being a secondary node currently serving the terminal; and sending the first message to the second node in response to the third message.

[0013] It can be understood that the third message can be regarded as a trigger condition for the first node to send the first message to the second node.

[0014] Based on the above scheme, the first node can request the second node to add the second node as a candidate auxiliary node of the terminal based on the identifier of the second node carried in the third message, and then the second node can subsequently allocate the corresponding first early synchronization configuration according to the first identification information carried in the third message, which is used for the subsequent early synchronization of the terminal and the second node for the first cell, so that the terminal can access the first cell in a random access-free manner, reduce the terminal's main and auxiliary cell switching delay, and improve the user's service experience.

[0015] In some implementations of the first aspect, the first message further includes first indication information, where the first indication information is used to request the LTM to add the second node as a candidate secondary node of the terminal.

[0016] Based on the above scheme, by sending the first indication information, the second node can determine whether to accept LTM and add the second node as a candidate auxiliary node of the terminal according to the first indication information. If the second node agrees to be a candidate auxiliary node of the terminal, it means that subsequent terminals can realize cell switching between base stations in the LTM switching scenario, and the terminal can communicate with the second node.

[0017] In certain implementations of the first aspect, the first message further includes identification information of K recommended (or suggested) cells, where the K cells include the first cell, K is an integer greater than or equal to 1, and the first cell belongs to the second node.

[0018] It is understandable that the recommended K cells belong to the second node, and the signal quality of the recommended K cells is generally good, for example, the signal quality of the K cells is greater than or equal to the first threshold, wherein the K cells include the first cell.

[0019] Based on the above scheme, the second node receives the identification information of the recommended K cells and determines whether to accept the K cells recommended by the first node as the cells of the terminal. For example, the second node can select a cell with good quality from the K cells as the target cell of the terminal, that is, the first cell. In other words, the second node accepts the primary and secondary cells of the terminal as the first cell, and selects the first cell with better signal quality as the target cell of the terminal, which is conducive to improving communication quality and ensuring user experience.

[0020] In some implementations of the first aspect, the third message further includes second indication information, where the second indication information is used to trigger the first node to request to add the second node as a candidate secondary node of the terminal with respect to the LTM.

[0021] Based on the above scheme, by sending the second indication information, the first node is triggered to request to add the second node as a candidate auxiliary node of the terminal. If the second node agrees to be a candidate auxiliary node of the terminal, it means that subsequent terminals can realize cell switching between base stations in the LTM switching scenario, and the terminal can communicate with the second node.

[0022] In certain implementations of the first aspect, the third message further includes identification information of the K cells.

[0023] Based on the above scheme, the third node can recommend or suggest K cells to the first node, so that when the terminal's current serving cell quality is poor or the terminal's cell signal quality is good, it can switch to the cell, which is conducive to improving communication quality and ensuring the user's service experience.

[0024] In certain implementations of the first aspect, the method further includes: sending a fourth message to a third node, where the fourth message includes the first early synchronization configuration, wherein the third node is a secondary node currently serving the terminal.

[0025] Based on the above scheme, the first node can send the first early synchronization configuration to the third node, and then the third node can, based on the first early synchronization configuration, instruct the terminal through the second cell to initiate early synchronization for the first cell. The second cell belongs to the third node. Then, after executing the early synchronization process for the first cell, the terminal can access the second node in a random access-free manner according to the received cell switching command, thereby reducing the terminal's primary and secondary cell switching delay, avoiding service drops or interruptions, and ensuring the user's service experience.

[0026] In certain implementations of the first aspect, the method also includes: receiving a fifth message from the second node, the fifth message including the timing advance TA of the first cell, the identifier of the third node and the first identifier information, the first cell belongs to the second node, and the third node is the auxiliary node currently serving the terminal.

[0027] It should be understood that the TA of the first cell is determined by the second node based on the random access preamble code from the terminal during the early synchronization process (or random access process) of the first cell.

[0028] In certain implementations of the first aspect, the method further includes: sending a sixth message to the third node in response to the fifth message, where the sixth message includes the TA and the first identification information of the first cell.

[0029] Exemplarily, the first node may forward the TA and the first identifier of the first cell, that is, the sixth message, to the third node based on the identifier of the third node in the fifth message.

[0030] Based on the above solution, the third node obtains the sixth message and determines the corresponding first early synchronization configuration based on the first identification information in the sixth message. Then, based on the correspondence between the random access preamble code included in the first early synchronization configuration and the terminal, the third node determines that the TA of the first cell is associated with the terminal, and can then send the TA of the first cell to the terminal. Subsequently, after receiving the handover command, the terminal can access the first cell based on the TA of the first cell in a non-random access manner, i.e., switch the terminal's primary or secondary cell to the first cell, thereby avoiding cell handover delays, avoiding service data interruption, and improving the user experience.

[0031] In certain implementations of the first aspect, the method further includes: receiving a seventh message from the third node, the seventh message being used to indicate that a switching command has been sent to the terminal, the switching command being used to instruct the primary and secondary cells of the terminal to switch to the first cell, and the seventh message including an identifier of the second node and identifier information of the first cell.

[0032] Based on the above scheme, the first node can determine that the third node has sent a switching command to the terminal by receiving the seventh message, and then the first node can indicate to the second node that the switching command has been sent to the terminal based on the identifier of the second node carried in the seventh message, so that the second node can monitor and ensure that the terminal is successfully switched to the first cell, so as to realize cell switching between nodes, reduce switching delay, and improve user experience.

[0033] In certain implementations of the first aspect, the method further includes: sending an eighth message to the second node in response to the seventh message, where the eighth message is used to indicate that a handover command has been sent to the terminal, and the eighth message includes identification information of the first cell.

[0034] Based on the above scheme, the second node can determine that a switching command has been sent to the terminal by receiving the eighth message. The second node can then determine that the terminal will switch to the first cell based on the identifier of the first cell. Then, the second node can monitor the first cell and successfully switch the primary and secondary cells of the terminal to the first cell, so as to realize cell switching between nodes, reduce switching delay, and improve user experience.

[0035] In certain implementations of the first aspect, the second message also includes a second early synchronization configuration, the fourth message also includes a second early synchronization configuration, and the method also includes: receiving a ninth message from the third node, the ninth message including the encapsulated second early synchronization configuration; in response to the ninth message, sending a tenth message to the terminal, the tenth message including the encapsulated second early synchronization configuration, the first early synchronization configuration and the encapsulated second early synchronization configuration are used for early synchronization of the first cell, and the first cell belongs to the second node.

[0036] In certain implementations of the first aspect, the first message further includes second identification information, the second identification information is used to request early synchronization configuration from the second node, and the second message further includes a third early synchronization configuration, the third early synchronization configuration corresponds to the second identification information.

[0037] Based on the above scheme, the present application does not limit the number of identification information carried in the first message. Correspondingly, the present application does not limit the number of advance synchronization configurations carried in the second message. As long as there is a corresponding relationship between the identification information and the advance synchronization configuration, the subsequent terminal can synchronize with the second node in advance for different cells, thereby reducing the switching delay of the terminal's primary and secondary cells, and ensuring the quality of service communication and user experience.

[0038] In the second aspect, a communication method is provided. The method is executed by a second node, or it can also be executed by other entities, and this application does not limit this. For the sake of convenience of description, the following is an example of execution by the second node. Among them, the second node can be a network device in a (dual-connectivity, DC) scenario, such as a candidate secondary node (SN), or a chip or circuit in a candidate SN, or a functional module in the candidate SN that can call and execute a program, etc. The method is applied to the LTM switching scenario.

[0039] The method includes: receiving a first message from a first node, the first message is used to request that the second node be added as a candidate auxiliary node of the terminal, the first message includes first identification information, and the first identification information is used to request early synchronization configuration; sending a second message to the first node, the second message is used to confirm that the second node is added as a candidate auxiliary node of the terminal, the second message includes a first early synchronization configuration, and the first early synchronization configuration corresponds to the first identification information.

[0040] According to the above solution, the second node receives the first identification information sent from the first node to allocate the first advance synchronization configuration, enabling the terminal to achieve advance synchronization with the second node in the LTM handover scenario. In this case, the terminal in the dual-connection scenario is connected to the first node and the second node respectively, and the terminal has completed the advance synchronization process with the second node before receiving the cell handover command. Subsequently, after receiving the cell handover command, the terminal can access the second node in a random access-free manner, reducing the terminal's primary and secondary cell handover delay, avoiding service drops or interruptions, and ensuring the user's service experience.

[0041] In certain implementations of the second aspect, the method further includes: sending a fifth message to the first node, the fifth message including the timing advance TA of the first cell, the identifier of the third node and the first identifier information, the first cell belongs to the second node, and the TA is determined during the advance synchronization process of the first cell.

[0042] In certain implementations of the second aspect, the method further includes: receiving an eighth message from the first node, the eighth message being used to indicate that a switching command has been sent to the terminal, the switching command being used to instruct the primary and secondary cells of the terminal to switch to the first cell, and the eighth message including identification information of the first cell.

[0043] In certain implementations of the second aspect, the first early synchronization configuration includes a random access preamble index and / or a random access time-frequency resource.

[0044] In some implementations of the second aspect, the first message further includes first indication information, where the first indication information is used to request the LTM to add the second node as a candidate secondary node of the terminal.

[0045] In certain implementations of the second aspect, the first message further includes identification information of K recommended cells, where the K cells include the first cell, the first cell belongs to the second node, and K is an integer greater than or equal to 1. In certain implementations of the second aspect, the first message further includes second identification information, where the second identification information is used to request an early synchronization configuration from the second node, and the second message further includes a third early synchronization configuration, where the third early synchronization configuration corresponds to the second identification information.

[0046] The beneficial effects of the above-mentioned second aspect and certain implementation methods of the second aspect can be referred to the description of the first aspect and related implementation methods of the first aspect, and will not be repeated here.

[0047] On the third aspect, a communication method is provided. The method is executed by a third node, or it can also be executed by other entities, and this application does not limit this. For the sake of convenience of description, the following is an example of execution by a third node, and the third node is a secondary node currently serving the terminal. Among them, the third node can be a network device in a (dual-connectivity, DC) scenario, such as a source secondary node (SN), or a chip or circuit in the source SN, or a functional module in the source SN that can call and execute a program, etc. The method is applied to the LTM switching scenario.

[0048] The method includes: determining a third message, the third message including the identifier of the second node and the first identifier information, the third message being used to trigger the first node to request the second node to configure early synchronization for the first identifier information; and sending the third message to the first node.

[0049] According to the above solution, the third node can allocate first identification information to the first node, which is used by the first node to request the second node to configure a first early synchronization configuration corresponding to the first identification information, so that the terminal and the second node can achieve early synchronization in the LTM handover scenario. Moreover, before receiving the cell handover command, the terminal has completed the early synchronization process with the second node. Subsequently, after receiving the cell handover command, the terminal can access the second node through a random access-free method, reducing the terminal's primary and secondary cell handover delay, avoiding service drops or interruptions, and ensuring the user's service experience.

[0050] In certain implementations of the third aspect, the method also includes: receiving a fourth message from the first node, the fourth message including a first early synchronization configuration, the first early synchronization configuration corresponding to the first identification information; based on the first early synchronization configuration, instructing the terminal through the second cell to initiate early synchronization for the first cell, wherein the first early synchronization configuration is the configuration of the first cell, the first cell belongs to the second node, and the second cell belongs to the third node.

[0051] In certain implementations of the third aspect, the first early synchronization configuration is associated with the second cell.

[0052] Based on the above scheme, the third node can determine the second cell according to the first early synchronization configuration carried in the fourth message, and then initiate early synchronization to the terminal through the second cell, so that the terminal and the second node can perform early synchronization of the first cell. Then, after receiving the switching command, the subsequent terminal can access the first cell in a random access-free manner, thereby enabling the terminal to achieve cell switching between base stations in the LTM switching scenario, and reducing the cell switching delay to ensure user service experience.

[0053] In certain implementations of the third aspect, the fourth message also includes a second early synchronization configuration, and the method also includes: in response to the fourth message, sending a ninth message to the first node, the ninth message including the encapsulated second early synchronization configuration, and the encapsulated second early synchronization configuration is used for early synchronization of the first cell.

[0054] In certain implementations of the third aspect, the method further includes: receiving a sixth message from the first node, where the sixth message includes a timing advance TA and first identification information of the first cell.

[0055] In certain implementations of the third aspect, the method further includes: determining the TA-associated terminal of the first cell according to the sixth message; sending a switching command to the terminal, the switching command being used to instruct the primary and secondary cells of the terminal to switch to the first cell, and the switching command including the TA of the first cell.

[0056] In certain implementations of the third aspect, the method further includes: sending a seventh message to the first node, the seventh message being used to indicate that a handover command has been sent to the terminal, the seventh message including an identifier of the second node and identifier information of the first cell.

[0057] In certain implementations of the third aspect, the third message further includes second indication information, where the second indication information is used to trigger the first node to request, with respect to the LTM, that the second node be added as a candidate secondary node of the terminal.

[0058] In certain implementations of the third aspect, the third message further includes identification information of K recommended cells, where the K cells include the first cell, the first cell belongs to the second node, and K is an integer greater than or equal to 1.

[0059] The beneficial effects of the third aspect and certain implementations of the third aspect can be referred to in the description of the first aspect and related implementations of the first aspect, and will not be repeated here.

[0060] In a fourth aspect, a communication device is provided. The communication device has the functions of implementing the first aspect above. For example, the communication device includes a module, unit, or means corresponding to performing the operations involved in the first aspect above. The module, unit, or means can be implemented through software, hardware, or a combination of software and hardware.

[0061] In one possible design, the communication device includes: a transceiver unit for sending a first message to the second node, the first message being used to request that the second node be added as a candidate auxiliary node of the terminal, the first message including first identification information, and the first identification information being used to request an early synchronization configuration from the second node; the transceiver unit is also used to receive a second message from the second node, the second message being used to confirm that the second node is added as a candidate auxiliary node of the terminal, the second message including a first early synchronization configuration, and the first early synchronization configuration corresponds to the first identification information.

[0062] The transceiver unit can perform the reception and transmission processing in the aforementioned first aspect. The communication device also includes a processing unit, which can perform other processing except reception and transmission in the aforementioned first aspect.

[0063] Exemplarily, the above-mentioned communication device may be an MN in a DC scenario, or a chip or circuit in the MN, or a functional module in the MN that can call and execute a program.

[0064] In a fifth aspect, a communication device is provided. The communication device has the functions of implementing the second aspect above. For example, the communication device includes a module, unit, or means corresponding to performing the operations involved in the first aspect above. The module, unit, or means can be implemented through software, hardware, or a combination of software and hardware.

[0065] In one possible design, the communication device includes: a transceiver unit for receiving a first message from a first node, the first message being used to request that the second node be added as a candidate auxiliary node of the terminal, the first message including first identification information, and the first identification information being used to request an early synchronization configuration; the transceiver unit is also used to send a second message to the first node, the second message being used to confirm that the second node is added as a candidate auxiliary node of the terminal, the second message including a first early synchronization configuration, and the first early synchronization configuration corresponding to the first identification information.

[0066] The transceiver unit can perform the reception and transmission processing in the aforementioned second aspect. The communication device also includes a processing unit, which can perform other processing in addition to the reception and transmission in the aforementioned second aspect.

[0067] Exemplarily, the above-mentioned communication device may be a candidate SN in a DC scenario, or a chip or circuit in a candidate SN, or a functional module in the candidate SN that can call and execute a program.

[0068] In a sixth aspect, a communication device is provided. The communication device has the functions of implementing the third aspect above. For example, the communication device includes a module, unit, or means corresponding to performing the operations involved in the first aspect above. The module, unit, or means can be implemented by software, hardware, or a combination of software and hardware.

[0069] In one possible design, the communication device includes: a processing unit, used to determine a third message, the third message including the identifier of the second node and the first identifier information, the third message being used to trigger the first node to request the second node to perform an advance synchronization configuration for the first identifier information; and a transceiver unit, used to send the third message to the first node.

[0070] The transceiver unit can perform the receiving and sending processing in the aforementioned third aspect, and the processing unit can perform other processing except receiving and sending in the aforementioned third aspect.

[0071] Exemplarily, the above-mentioned communication device can be a source SN in a DC scenario, or a chip or circuit in the source SN, or a functional module in the source SN that can call and execute a program.

[0072] In a seventh aspect, a communication device is provided. The communication device may be the first communication device or the second communication device described above. The communication device includes a transceiver, a processor, and a memory. The processor is configured to control the transceiver to transmit and receive signals. The memory is configured to store a computer program. The processor is configured to retrieve and execute the computer program from the memory, so that the communication device performs the method of any possible implementation of the first to third aspects described above.

[0073] Optionally, there are one or more processors and one or more memories.

[0074] Optionally, the memory may be integrated with the processor, or the memory may be provided separately from the processor.

[0075] Optionally, the communication device further includes a transmitter (transmitter) and a receiver (receiver).

[0076] In an eighth aspect, a communication system is provided. The communication system includes a first node, a second node, and a third node, wherein the first node is configured to execute the method in any possible implementation of the first aspect, the second node is configured to execute the method in any possible implementation of the second aspect, and the third node is configured to execute the method in any possible implementation of the third aspect.

[0077] Exemplarily, the first node may be a MN, or a chip or circuit in the MN, or a functional module in the MN that can call and execute a program.

[0078] Exemplarily, the second node may be a candidate SN, or a chip or circuit in the candidate SN, or a functional module in the candidate SN that can call and execute a program.

[0079] Exemplarily, the third node may be the source SN, or a chip or circuit in the source SN, or a functional module in the source SN that can call and execute a program.

[0080] In a ninth aspect, a computer-readable storage medium is provided. The computer-readable storage medium stores computer program code or instructions, and when the computer program code or instructions are executed, the method in any possible implementation of the first to third aspects is implemented.

[0081] In a tenth aspect, a chip is provided. The chip includes at least one processor coupled to a memory, the memory being configured to store a computer program. When the computer program is executed, the method of any possible implementation of the first to third aspects is implemented.

[0082] Illustratively, the chip may include an input circuit or interface for sending information or data, and an output circuit or interface for receiving information or data.

[0083] In an eleventh aspect, a computer program product is provided, comprising computer program code or instructions, which, when executed, implements the method in any possible implementation of the first to third aspects.

[0084] In a twelfth aspect, a computer program is provided, which, when executed, implements the method in any possible implementation manner of the first to third aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0085] FIG1 is a schematic diagram of a system architecture applicable to an embodiment of the present application.

[0086] FIG2 is a schematic block diagram of a terminal supporting EN-DC.

[0087] FIG3 is a schematic block diagram of a terminal supporting MR-DC.

[0088] FIG4 is a schematic block diagram of a MN and a SN in an MR-DC scenario.

[0089] FIG5 is a schematic flow chart of LTM switching.

[0090] FIG6 is a schematic flowchart of a communication method provided in an embodiment of the present application.

[0091] FIG7 is a schematic flowchart of another communication method provided in an embodiment of the present application.

[0092] FIG8 is a schematic block diagram of a communication device provided in an embodiment of the present application.

[0093] FIG9 is a schematic diagram of another communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0094] The technical solution in this application will be described below with reference to the accompanying drawings.

[0095] First, in this application, "used to indicate" or "indicate" can include being used for direct indication and being used for indirect indication. When describing that a certain indication information is used to indicate A, it can include that the indication information directly indicates A or indirectly indicates A, and it does not necessarily mean that the indication information carries A.

[0096] The information indicated by the indication information is called the information to be indicated. In the specific implementation process, there are many ways to indicate the information to be indicated, such as but not limited to, directly indicating the information to be indicated, such as the information to be indicated itself or the index of the information to be indicated. The information to be indicated can also be indirectly indicated by indicating other information, wherein there is an association between the other information and the information to be indicated. It is also possible to indicate only a part of the information to be indicated, while the other parts of the information to be indicated are known or agreed in advance. For example, it is also possible to use the arrangement order of each piece of information agreed in advance (such as specified in the protocol) to achieve the indication of specific information, thereby reducing the indication overhead to a certain extent. At the same time, it is also possible to identify the common parts of each piece of information and indicate them uniformly to reduce the indication overhead caused by indicating the same information separately.

[0097] Second, in this application, "at least one" means one or more, and "a plurality" means two or more. In addition, in the embodiments of this application, "first", "second", and various numerical numbers (for example, "#1", "#2", etc.) are only used for the convenience of description and are not intended to limit the scope of the embodiments of this application.

[0098] Third, in the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described in the present application as "exemplary" or "for example" should not be interpreted as being more preferred or more advantageous than other embodiments or design. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a concrete way. In addition, in various embodiments, "optionally, the method further includes..." can be understood as these steps can be executed in full, or none of them can be executed, or only part of them can be executed, and this application does not limit it.

[0099] It should be understood that references to "embodiments" throughout this specification mean that a particular feature, structure, or characteristic associated with the embodiment is included in at least one embodiment of the present application. Therefore, various embodiments throughout this specification do not necessarily refer to the same embodiment. Furthermore, these particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0100] Fourth, the term "storage" used in the embodiments of this application may refer to storage in one or more memories. The one or more memories may be provided separately or integrated into an encoder or decoder, a processor, or a communication device. The one or more memories may also be partially provided separately and partially integrated into a decoder, a processor, or a communication device. The type of memory may be any form of storage medium, and this application is not limited thereto.

[0101] Fifth, in the implementation of this application, "protocol" may refer to a standard protocol in the field of communications, for example, it may include the NR protocol and related protocols used in future communication systems, and this application does not limit this.

[0102] Sixth, in the embodiments of the present application, the terms “of”, “corresponding, relevant”, “corresponding” and “associate” can sometimes be used interchangeably. It should be noted that when the distinction between them is not emphasized, the meanings they intend to express are consistent.

[0103] Seventh, in the embodiments of the present application, "when...", "when...", and "if..." can sometimes be used interchangeably. It should be noted that when the distinction is not emphasized, the meanings they intend to express are consistent. It should also be understood that in the present application, "when...", "if...", "when...", and "if" all refer to the network element making corresponding processing under certain objective circumstances. They are not time-limited, and do not require that the device must have a judgment action when implementing them, nor do they imply the existence of other limitations. In addition, in the present application, the descriptions of the above-mentioned "when...", "if...", "when...", and "if" conditions can be understood as necessary conditions, and there is no limitation on whether the condition is a sufficient condition or whether it is a necessary and sufficient condition. For example, "when A is present, execute B" can be understood as "when at least A is satisfied, execute B."

[0104] Eighth, in each embodiment of the present application, "B corresponding to A" or "A corresponds to B" means that B is associated with A and B can be determined based on A. However, it should be understood that determining B based on A does not mean determining B based solely on A; B can also be determined based on A and / or other information.

[0105] Ninth, in this application, the term "and / or" is simply a description of the relationship between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the related objects are in an "or" relationship.

[0106] In addition, the terms "system", "network" and "device" in the embodiments of the present application can be used interchangeably.

[0107] Ninth, in each embodiment of the present application, "in response to A, execute B" can also be replaced by: "execute B according to A" or "execute B based on A" and other expressions to indicate that there is an association relationship between A and B. Similar parts will not be repeated below.

[0108] Tenth, in this application, "sending information" can be understood as one device sending information to another device, or as one logic module within a device sending information to another logic module. For example, "a network device sending information" can be understood as the network device sending information to another device (such as a terminal), or as logic module 1 within the network device sending information to logic module 2 within the network device.

[0109] In this application, "receiving information" can be understood as one device receiving information from another device, or it can also be understood as a logic module within a device receiving information from another logic module. For example, "a network device receiving information" can be understood as the network device receiving information from another device (such as a terminal), or it can be understood as logic module 1 in the network device receiving information from logic module 2 in the network device.

[0110] In addition, in this application, "sending information to... (access network device)" can be understood as the destination end of the information being the access network device. This can include sending information directly or indirectly to the access network device. "Receiving information from... (access network device)" can be understood as the source end of the information being the access network device, which can include receiving information directly or indirectly from the access network device. The information may undergo necessary processing between the source end and the destination end of the information transmission, such as format changes, etc., but the destination end can understand the valid information from the source end. Similar expressions in this application can be understood similarly and will not be repeated here.

[0111] It is understandable that in the following various method embodiments, the methods and operations implemented by a device (such as a network device, a terminal) may also be implemented by components of the device (such as a chip or a circuit).

[0112] It should be understood that in the various embodiments of the present application, the size of the sequence number of each process below does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute a limitation on the implementation process of the embodiment of the present application. It should be understood that the objects described in this way can be interchanged where appropriate so as to be able to describe schemes other than the embodiments of the present application. In addition, in the embodiments of the present application, words such as "S610" are only identifiers made for the convenience of description and do not limit the order of execution steps. The names of all nodes and messages in this application are merely names set by this application for the convenience of description. The names in the actual network may be different. It should not be understood that this application limits the names of various nodes and messages. On the contrary, any name with the same or similar function as the node or message used in this application is regarded as a method or equivalent replacement of this application and is within the scope of protection of this application.

[0113] For ease of description, the system architecture of the embodiment of the present application is introduced in detail below.

[0114] The technical solutions of the embodiments of the present application can be applied to various communication systems, such as: long term evolution (LTE) system, LTE frequency division duplex (FDD) system, LTE time division duplex (TDD), fifth generation (5G) system or new radio (NR) and future communication systems, vehicle-to-X (V2X), where V2X may include vehicle to network (V2N), vehicle to vehicle (V2V), vehicle to infrastructure (V2I), vehicle to pedestrian (V2P), etc., long term evolution technology for vehicle communication (LTE-V), Internet of Vehicles, machine type communication (MTC), Internet of Things (IoT), long term evolution technology for machine-to-machine communication (LTE-M), machine to machine (M2M), etc. This application can also be applied to future communication systems, such as the sixth generation (6G) mobile communication system.

[0115] In an embodiment of the present application, the terminal device may also be referred to as user equipment (UE), access terminal, user unit, user station, mobile station, mobile station, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication device, user agent or user device.

[0116] The terminal devices in the embodiments of the present application include various devices with wireless communication functions, which can be used to connect people, objects, machines, etc. The terminal devices can be widely used in various scenarios, such as: cellular communication, D2D, V2X, peer to peer (P2P), M2M, MTC, IoT, virtual reality (VR), augmented reality (AR), industrial control, autonomous driving, telemedicine, smart grid, smart furniture, smart office, smart wearable, smart transportation, smart city drones, robots, remote sensing, passive sensing, positioning, navigation and tracking, autonomous delivery, etc. The terminal device can be a terminal in any of the above scenarios, such as an MTC terminal, an IoT terminal, etc. The terminal device may be a user equipment (UE) of the third generation partnership project (3GPP) standard, a terminal, a fixed device, a mobile station device or a mobile device, a subscriber unit, a handheld device, a vehicle-mounted device, a wearable device, a cellular phone, a smart phone, a session initialization protocol (SIP) phone, a wireless data card, a personal digital assistant (PDA), a computer, a tablet computer, a notebook computer, a wireless modem, a handheld device (handset), a laptop computer, a computer with wireless transceiver function, a smart book, a vehicle, a satellite, a global positioning system (GPS) device, a target tracking device, an aircraft (such as a drone, a helicopter, a multi-copter, a quadcopter, or an airplane), a ship, a remote control device, a smart home device, an industrial device, or a device built into the above-mentioned device (such as a communication module, a modem or a chip in the above-mentioned device), or other processing devices connected to a wireless modem. For the sake of convenience of description, the terminal device will be described below by taking the terminal or UE as an example.

[0117] Wearable devices, also known as wearable smart devices, are a general term for wearable devices that use wearable technology to intelligently design and develop wearable devices for daily wear, such as glasses, gloves, watches, clothing, and shoes. Wearable devices are portable devices that are worn directly on the body or integrated into the user's clothing or accessories. Wearable devices are not just hardware devices, but also achieve powerful functions through software support, data interaction, and cloud interaction. In a broad sense, wearable smart devices include those that are fully functional, large in size, and can achieve full or partial functions without relying on smartphones, such as smart watches or smart glasses, as well as those that only focus on a certain type of application function and need to be used in conjunction with other devices such as smartphones, such as various smart bracelets and smart jewelry for vital sign monitoring.

[0118] Furthermore, terminal devices can also be end devices in the Internet of Things (IoT) system. IoT is a crucial component of future information technology development. Its primary technical feature is connecting objects to the Internet through communications technology, thereby enabling intelligent networks that interconnect humans and machines, and objects and things. IoT technology, for example, utilizes narrowband (NB) technology to achieve massive connectivity, deep coverage, and power-saving terminals.

[0119] In an embodiment of the present application, the terminal device can also be a vehicle or a whole vehicle, which can achieve communication through the Internet of Vehicles, or it can be a component located in the vehicle (for example, placed in the vehicle or installed in the vehicle), that is, a vehicle-mounted terminal device, a vehicle-mounted module or an on-board unit (OBU).

[0120] In addition, terminal devices can also include sensors such as smart printers, train detectors, and gas stations. Their main functions include collecting data (part of the terminal devices), receiving control information and downlink data from network devices, and sending electromagnetic waves to transmit uplink data to network devices.

[0121] In this application, the device for implementing the function of a terminal device may be a terminal device; it may also be a device capable of supporting the terminal device in implementing the function, such as a chip system, a hardware circuit, a software module, or a hardware circuit and a software module. The device may be installed in the terminal device or may be used in conjunction with the terminal device. In the technical solutions provided in this disclosure, the technical solutions provided in this disclosure are described by taking the device for implementing the function of a terminal device as a terminal device, and the terminal device as a UE as an example.

[0122] The network device in the embodiment of the present application is an entity on the network side for transmitting or receiving signals, which can be used to convert received air frames into Internet Protocol (IP) packets, and serve as a router between the terminal device and the rest of the access network, where the rest of the access network may include an IP network, etc.

[0123] The network device in the embodiment of the present application may be a device for communicating with a terminal device, and the network device may also be referred to as an access network device or a radio access network device, such as a base station. The network device in the embodiment of the present application may refer to a radio access network (RAN) node (or device) that connects a terminal device to a wireless network. The RAN may be an open access network (open RAN, O-RAN or ORAN), a cloud radio access network (CRAN), or a wireless fidelity (WiFi) system. The RAN may also be a communication system that is a fusion of two or more of the above systems. Base station can broadly cover various names as follows, or replace with the following names, such as: NodeB, evolved NodeB (eNB), next generation NodeB (gNB), relay station, access point, transmission point (TRP), transmission point (TP), master station, auxiliary station, multi-standard radio (motor slide retainer, MSR) node, home base station, network controller, access node, wireless node, access point (AP), transmission node, transceiver node, baseband unit (BBU), remote radio unit (RRU), active antenna unit (AAU), remote radio head (RRH), central unit (CU), distributed unit (DU), positioning node, etc. The base station can be a macro base station, a micro base station, a relay node, a donor node or the like, or a combination thereof. The base station can also refer to a communication module, modem or chip used to be set in the aforementioned device or apparatus. The base station can also be a mobile switching center and a device that performs base station functions in D2D, V2X, and M2M communications, a network-side device in a 6G network, or a device that performs base station functions in future communication systems. The base station can support networks with the same or different access technologies. The embodiments of this application do not limit the specific technology and specific device form used by the network equipment.

[0124] Base stations can be fixed or mobile. For example, a helicopter or drone can be configured to act as a mobile base station, and one or more cells can move based on the location of the mobile base station. In other examples, a helicopter or drone can be configured to act as a device that communicates with another base station.

[0125] In some deployments, a gNB may include a CU and a DU. The CU and DU may be connected via an interface, such as the F1 interface. The gNB may also include an active antenna unit (AAU). The CU implements some gNB functions, while the DU implements some gNB functions. For example, the CU is responsible for processing non-real-time protocols and services, implementing the functions of the radio resource control (RRC) and packet data convergence protocol (PDCP) layers. The DU is responsible for processing physical layer protocols and real-time services, implementing the functions of the radio link control (RLC), medium access control (MAC), and physical (PHY) layers. The AAU implements some physical layer processing functions, RF processing, and active antenna-related functions. Because RRC layer information ultimately becomes PHY layer information, or is converted from PHY layer information, in this architecture, higher-layer signaling, such as RRC layer signaling, can also be considered to be sent by the DU, or by both the DU and the CU. It is understood that the network device may include one or more of a CU node, a DU node, and an AAU node. In addition, the CU may be classified as a network device in an access network (RAN) or a network device in a core network (CN), which is not limited in this application.

[0126] In different systems, CU (or centralized unit control plane (CU-control plane, CU-CP) and distributed unit user plane (CU-user plane, CU-UP)), DU or RU may also have different names, but those skilled in the art can understand their meanings. For example, in the ORAN system, CU may also be called O-CU (Open CU), DU may also be called O-DU, CU-CP may also be called O-CU-CP, CU-UP may also be called O-CU-UP, and RU may also be called O-RU. For convenience of description, this application uses CU, CU-CP, CU-UP, DU and RU as examples for description. Any of the CU (or CU-CP, CU-UP), DU and RU in this application can be implemented by a software module, a hardware module, or a combination of a software module and a hardware module.

[0127] The above-mentioned network equipment provides services for the cell, and the terminal device communicates with the cell through the transmission resources (for example, frequency domain resources, or spectrum resources) allocated by the network equipment. The cell can belong to a macro base station (for example, macro eNB or macro gNB, etc.), or it can belong to a base station corresponding to a small cell. The small cells here may include: metro cells, micro cells, pico cells, femto cells, etc. These small cells have the characteristics of small coverage and low transmission power, and are suitable for providing high-speed data transmission services.

[0128] In this application, the device for implementing the functions of an access network device may be the access network device; it may also be a device capable of supporting the access network device in implementing the functions, such as a chip system, a hardware circuit, a software module, or a hardware circuit and a software module. The device may be installed in the access network device or may be used in conjunction with the access network device. In the technical solutions provided in this application, the technical solutions provided in this application are described by taking the device for implementing the functions of the access network device as the access network device, and the access network device as a base station as an example.

[0129] In the embodiment of the present application, a network device may include one or more cells, and each cell may include one or more transmission reception points (TRPs) or transmission points (TPs).

[0130] Network devices and terminal devices can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; they can also be deployed on the water surface; they can also be deployed on aircraft, balloons and satellites in the air. The embodiments of this application do not limit the scenarios in which network devices and terminal devices are located. In addition, terminal devices and network devices can be hardware devices, or they can be software functions running on dedicated hardware, software functions running on general-purpose hardware, such as virtualization functions instantiated on a platform (e.g., a cloud platform), or entities including dedicated or general-purpose hardware devices and software functions. This application does not limit the specific forms of terminal devices and network devices.

[0131] Figure 1 is a schematic diagram of a communication system 100 applicable to an embodiment of the present application. As shown in Figure 1 , the communication system 100 may include at least one terminal device, such as the terminal device 110 shown in Figure 1 . The communication system 100 may also include at least two network devices, such as the network device 120 and the network device 130 shown in Figure 1 . Terminal device 110 may communicate with both network device 120 and network device 130 simultaneously. For example, communication between terminal device 110 and network device 120, and between terminal device 110 and network device 130, may occur via a wireless link. Each communication device, such as terminal device 110, network device 120, or network device 130, may be configured with multiple antennas. For each communication device in the communication system, the multiple antennas configured may include at least one transmit antenna for transmitting signals and at least one receive antenna for receiving signals. Therefore, communication between the communication devices in the communication system, between terminal device 110 and network device 120, and between terminal device 110 and network device 130, may occur using multi-antenna technology.

[0132] It should be understood that FIG1 is only a simplified schematic diagram for ease of understanding, and the communication system may further include other network devices or other terminal devices, which are not shown in FIG1 .

[0133] It should also be understood that the simultaneous communication between terminal device 110 and network device 120 and network device 130 may also be referred to as dual-connectivity (DC) of the terminal device. One network device communicating with terminal device 110 may be referred to as a master node (MN), and the other network device communicating with terminal device 110 may be referred to as a secondary node (SN). As an example, assume that network device 120 is an MN and network device 130 is an SN.

[0134] As an example, based on the different types of MNs and SNs, DC scenarios can be further divided into EN-DC and MR-DC. EN-DC and MR-DC are described in detail below.

[0135] 1. EN-DC;

[0136] EN-DC refers to LTE and 5G dual connectivity. The letter E stands for evolved universal terrestrial radio access new radio (E-UTRA), which is the air interface in LTE cellular networks. The letter N stands for new radio (NR), which is a global standard for a unified and more powerful 5G wireless air interface. In other words, terminal devices that support EN-DC can simultaneously connect to the LTE master node eNB (MN-eNB) and the 5G-NR secondary node gNB (SN-gNB). EN-DC is a technology that enables the introduction of 5G services and data rates in networks that are primarily 4G.

[0137] Figure 2 is a schematic block diagram of a terminal device (e.g., UE) that supports EN-DC. As shown in Figure 2, the bearers in the network can be divided into three categories: master cell group (MCG) bearers, secondary cell group (SCG) bearers, and Split bearers. In EN-DC, the MCG bearer uses the PDCP, RLC, and MAC corresponding to the master node. For EN-DC, 4G (E-UTRA) is the master node, so the MCG bearer uses E-UTRA PDCP, E-UTRA RLC, and E-UTRA MAC. The SCG bearer uses the PDCP, RLC, and MAC corresponding to the secondary node. For EN-DC, 5G-NR (gNB) is the secondary node, so the SCG bearer uses NR PDCP, NR RLC, and NR MAC. Split bearer splits the air interface data into two bearers. NR PDCP is used in PDCP, E-UTRA RLC is used to carry the air interface data of MN in RLC, and NR RLC is used to carry the air interface data of SN. E-UTRA MAC is used to carry the air interface data of MN in MAC, and NR MAC is used to carry the air interface data of SN.

[0138] It should be understood that the LTE master node eNB (MN-eNB) uses multiple frequencies to form a multi-layer cell network. These cells can serve as control plane anchor points. Therefore, these 4G cells are collectively referred to as MCGs, and the wireless data bearers established on them are called MCG bearers. Correspondingly, multiple 5G cells form SCGs, and the wireless data bearers established on them are called SCG bearers. In comparison, split bearer refers to splitting the air interface data into two bearers.

[0139] 2. MR-DC;

[0140] MR-DC refers to 5G and 5G dual connectivity. Terminal devices that support MR-DC can simultaneously connect to the 5G-NR master node gNB (MN-gNB) and the 5G-NR secondary node gNB (SN-gNB).

[0141] Figure 3 is a schematic block diagram of a terminal device (e.g., UE) that supports MR-DC. As shown in Figure 3, the bearers in the network can be divided into three categories: master cell group (MCG) bearer, secondary cell group (SCG) bearer, and Split bearer. In MR-DC, the MCG bearer uses the PDCP, RLC, and MAC corresponding to the master node. For MR-DC, 5G-NR (gNB) is the master node, so the MCG bearer uses NR PDCP, MN RLC, and MN MAC. The SCG bearer uses the PDCP, RLC, and MAC corresponding to the secondary node. For MR-DC, 5G-NR (gNB) is the secondary node, so the SCG bearer uses NR PDCP, SN RLC, and SN MAC. Split bearer splits the air interface data into two bearers. NR PDCP is used in PDCP, MN RLC is used to carry the air interface data of MN in RLC, SN RLC is used to carry the air interface data of SN, MN MAC is used to carry the air interface data of MN in MAC, and SN MAC is used to carry the air interface data of SN.

[0142] Figure 4 is a schematic block diagram of a MN and SN in an MR-DC scenario. As shown in Figure 4, taking downlink data as an example, assuming the MN serves as the anchor point, after receiving data from the core network, for a split bearer, the downlink data is split starting at the PDCP layer and sent to the RLC / MAC layers of the MN and SN for processing. For example, the MN can send downlink data to a terminal device via the MN RLC and MN MAC layers within the MN. Alternatively, the MN can send the downlink data to the SN RLC within the SN, which then forwards the data to the terminal device via the SN RLC and MN MAC layers.

[0143] To facilitate understanding of the embodiments of the present application, some terms involved in the present application are first briefly explained.

[0144] 1. Timing advance (TA);

[0145] TA is generally used for uplink transmissions from a terminal. It means that the terminal sends uplink data in advance of the TA time according to the corresponding instructions. Specifically, to ensure that the terminal's uplink data reaches the network device at the desired time and to estimate the transmission delay caused by distance, the network device calculates the terminal's TA value based on the random access preamble sent by the terminal and notifies the terminal of the obtained TA value through a timing advance command (TAC).

[0146] 2. Random access;

[0147] Random access is a necessary process for establishing a wireless link between a terminal and the network. Only after random access is completed can data exchange between the network and the terminal proceed normally.

[0148] Random access can achieve the following three basic functions:

[0149] 1) The terminal achieves uplink synchronization with the network side, that is, the terminal obtains the TA value. Once the uplink is out of synchronization, the terminal can only transmit data on the physical random access channel (PRACH).

[0150] 2) The terminal applies for uplink grant (UL grant) resources for sending message 3 (Msg3).

[0151] 3) Allocate a unique cell radio network temporary identify (C-RNTI) to the terminal.

[0152] According to different service triggering methods, random access can be divided into contention based random access (CBRA) and contention free random access (CFRA). The so-called "contention" means that conflicts may occur between different terminals.

[0153] In a first implementation, contention-based random access includes the following steps:

[0154] In step 0, each terminal monitors system information. For example, the terminal obtains configuration information of the cell PRACH by monitoring system information block 1 (SIB1) or system information block 2 (SIB2).

[0155] In step 1, multiple terminals use the same PRACH resource in the same subframe and send the same preamble sequence to the network device to request resource authorization. At this time, the network device cannot know which terminal sent the request, and a conflict may occur.

[0156] Step 2: The network device sends a random access response (RAR) message. The RAR includes the TA value and the UL grant used to transmit message 3. Each terminal may receive the RAR sent by the network device.

[0157] In step 3, the multiple terminals that have received the RAR send a unique message related only to themselves, namely, message 3, to the network device when the UL grant is indicated.

[0158] In step 4, after receiving messages 3 from multiple terminals, the network device determines which terminal has successfully competed and sends message 4 (Msg4) to the terminal to confirm which terminal has successfully accessed. This mechanism is called contention resolution.

[0159] In the second implementation, non-contention random access includes the following steps:

[0160] In step 0, the network device sends random access preamble assignment information to the terminal via dedicated signaling. For example, the network device sends the preamble required for non-contention random access (hereinafter referred to as the non-contention preamble) and PRACH resources to the terminal. If the preamble resources are insufficient at this time, the network device notifies the terminal to initiate contention-based random access. One way to do this is to set the preamble index in PDCCH format 1a to all 0s. In this way, when the preamble index decoded by the terminal is all 0s, the terminal will perform contention-based random access.

[0161] In a handover scenario, a non-contention preamble is sent to the terminal via a handover command.

[0162] Step 1: The terminal sends a non-contention preamble code to the network device.

[0163] Step 2: The network device feeds back a RAR to the terminal, wherein the RAR includes a TA value.

[0164] It should be understood that the terminal determines that the random access is successful after receiving the RAR.

[0165] The following describes an example of an inter-site intra-cell handover solution in an LTM scenario with reference to FIG5 .

[0166] FIG5 is a schematic flow chart of LTM switching, which includes the following steps.

[0167] In this implementation, a CU under the base station can be connected to multiple DUs (e.g., source DU and candidate DUs). Before performing LTM switching, the terminal can transmit user-plane data with the source DU, and the source DU can transmit user-plane data with the CU. It should be noted that LTM switching means that the switching decision is sent from the CU to the DU, thereby reducing the F1 interaction between the CU and the DU. That is, the DU can determine whether to initiate a handover based on the measurement report reported by the terminal and send the handover command to the terminal.

[0168] S501: The terminal sends a measurement report to the source DU.

[0169] Accordingly, the source DU receives the measurement report from the terminal.

[0170] The measurement report includes layer 3 (layer 3, L3) measurement results, for example, measurement results of neighboring cells, where the measurement results may indicate signal quality of the neighboring cells, where the neighboring cells refer to cells to which the terminal may switch after moving.

[0171] S502: The source DU sends a measurement report to the CU.

[0172] Accordingly, the CU receives the measurement report from the source DU.

[0173] Exemplarily, the source DU may send an uplink (UL) RRC message to the CU, where the UL RRC message includes a measurement report, wherein the measurement report includes an L3 measurement result reported by the terminal.

[0174] S503: The CU determines to initiate LTM configuration according to the measurement report.

[0175] Exemplarily, the CU determines to initiate LTM configuration based on the measurement result of the neighboring cell carried in the measurement report (for example, the measurement result of the neighboring cell indicates that the signal quality of the neighboring cell is high).

[0176] S504: The CU sends a UE context modification request message to the candidate DU.

[0177] Accordingly, the candidate DU receives a UE context establishment request message from the CU.

[0178] The UE context establishment request message includes at least one of the identity (ID) of the first candidate cell, the LTM configuration ID of the first candidate cell, the LTM configuration ID mapping list (configuration identifier of the first cell) or the channel state information (CSI) resource configuration.

[0179] It should be noted that the candidate cells include the source cell, which belongs to the source DU. The number of candidate DUs is not limited here, that is, the CU of the base station corresponds to multiple DUs, and the number of candidate cells is not limited.

[0180] It is understandable that the CU may also indicate the ID of the source DU to request the candidate DU to provide a physical random access channel (PRACH) resource, that is, the configuration for early synchronization in the subsequent step S514.

[0181] Optionally, the CU may also request the candidate DU to provide a lower layer configuration for generating a reference configuration, that is, a lower layer RRC configuration corresponding to the first candidate cell.

[0182] S505: The candidate DU sends a UE context modification response message to the CU.

[0183] Accordingly, the CU receives a UE context establishment response message from the candidate DU.

[0184] Exemplarily, if the candidate DU accepts the request for LTM configuration, the candidate DU sends a UE context establishment response message to the CU. The UE context establishment response message includes: the lower layer RRC configuration corresponding to the first candidate cell (for example, including at least one of the following: transmission configuration indicator (TCI) state configuration, random access channel (RACH) configuration, CSI report configuration). The RACH configuration is also the early uplink synchronization configuration, and the CSI report configuration corresponds to the CSI resource configuration.

[0185] S506: The CU sends a UE context modification request message to the source DU.

[0186] Accordingly, the source DU receives the UE context modification request message from the CU.

[0187] The UE context modification request message includes: one or more of: CSI report configuration, RACH resource configuration, or TCI state configuration of the first candidate cell.

[0188] S507: The source DU sends a UE context modification response message to the CU.

[0189] Accordingly, the CU receives a UE context modification response message from the source DU.

[0190] The UE context modification response message includes an updated lower layer configuration, such as an updated CSI reporting configuration, and the CSI resource configuration corresponding to the CSI reporting configuration is used to send the lower layer measurement result of the first candidate cell in the source cell.

[0191] S508: The CU sends a UE context modification request message to the candidate DU.

[0192] Accordingly, the candidate DU receives the UE context modification request message from the CU.

[0193] The UE context modification request message may include CSI report configuration, TCI status information, RACH configuration and LTM Configuration ID of the first candidate cell.

[0194] Optionally, the CU may also indicate the updated CSI resource configuration to the candidate DU, or refer to the underlying part of the configuration.

[0195] S509: The candidate DU sends a UE context modification response message to the CU.

[0196] Accordingly, the CU receives a UE context modification response message from the candidate DU.

[0197] The UE context modification response message may include the updated underlying configuration, such as a generated CSI resource configuration, where the CSI resource configuration is used to send the CSI of the candidate cell on the first candidate cell.

[0198] Optionally, the candidate DU may indicate the updated CSI reporting configuration to the CU.

[0199] S510, the CU sends a downlink (DL) RRC message to the source DU.

[0200] Accordingly, the source DU receives the DL RRC message from the CU.

[0201] The DL RRC message includes an RRC reconfiguration message, and the RRC reconfiguration message includes an LTM configuration (for example, including at least one of the following: CSI report configuration, TCI state configuration, RACH configuration, or LTM Configuration ID of the first candidate cell).

[0202] S511: The source DU sends an RRC reconfiguration message to the terminal.

[0203] Accordingly, the terminal receives the RRC reconfiguration message from the source DU.

[0204] S512: The terminal sends an RRC reconfiguration completion message to the source DU.

[0205] Accordingly, the source DU receives an RRC reconfiguration complete message from the terminal.

[0206] S513: The source DU sends an UL RRC message to the CU.

[0207] Accordingly, the CU receives the UL RRC message from the source DU.

[0208] The UL RRC message includes an RRC reconfiguration completion message.

[0209] S514: The terminal and the candidate DU perform early synchronization.

[0210] Exemplarily, according to the random access resource configuration of the first candidate cell, the terminal and the candidate DU perform early synchronization on the first candidate cell, where the early synchronization includes early uplink synchronization or downlink synchronization. Early uplink synchronization can be achieved by acquiring a timing advance (TA) through random access.

[0211] S515, the candidate DU sends a DU-CU information transmission message to the CU;

[0212] Accordingly, the CU receives the DU-CU information transmission message from the candidate DU.

[0213] The DU-CU information transmission message includes one or more of the following: the TA value of the first candidate cell, associated non-contention random access (CFRA) resource information, the identification ID of the first candidate cell, or the identification ID of the source DU.

[0214] S516, the CU sends a CU-DU information transmission message to the source DU;

[0215] Accordingly, the source DU receives the CU-DU information transmission message from the CU.

[0216] The CU-DU information transmission message includes: the TA of the first candidate cell, associated CFRA resource information, or the identification ID of the first candidate cell.

[0217] It should be noted that the above steps S514, S515, and S516 are optional steps and may not be performed. That is, the terminal and the candidate DU may not be synchronized in advance with respect to the first candidate cell, and may perform uplink synchronization and downlink synchronization when the terminal communicates with the candidate DU.

[0218] S517: The terminal sends a measurement report to the source DU.

[0219] Accordingly, the source DU receives the measurement report from the terminal.

[0220] The measurement report includes lower layer measurement results of the terminal, such as layer 1 (L1) measurement results. Exemplarily, the terminal measures the RS according to the RS configuration, and then sends the measurement results to the source DU according to the CSI resource configuration.

[0221] S518: The source DU determines to perform LTM handover on the candidate cell according to the measurement report.

[0222] S519: The source DU sends an LTM cell switching command to the terminal.

[0223] Accordingly, the terminal receives the LTM switching command from the source DU.

[0224] The LTM cell handover command includes the identifier of the target cell (or the identifier of the first candidate cell), and the LTM cell handover command is used to indicate the first candidate cell as the target cell for handover of the terminal from the source cell.

[0225] Optionally, the LTM cell switching command may also include: beam information of the target cell (for example, TCI state identifier) ​​and / or timing advance information of the target cell, where the beam information is used for the terminal to receive downlink control information in a random access-free manner.

[0226] S520: The source DU sends a DU-CU cell switching notification message to the CU.

[0227] Accordingly, the CU receives the DU-CU cell switching notification message from the source DU.

[0228] The DU-CU cell handover notification message is used to indicate that an LTM cell handover command has been initiated for the terminal. The DU-CU cell handover notification message includes the identifier of the target cell and the beam information of the target cell. It is understood that the target cell is a candidate cell in the aforementioned steps, such as the first candidate cell. The following description uses the target DU instead of the candidate DU.

[0229] S521: The CU sends a CU-DU cell switching notification message to the target DU.

[0230] Accordingly, the target DU receives the CU-DU cell switching notification message from the CU.

[0231] The CU-DU cell handover notification message includes the identifier of the target cell and the beam information of the target cell. It can be understood that the target DU is one of the candidate DUs in the above steps, that is, the DU corresponding to the target cell.

[0232] S522: The target DU detects terminal access.

[0233] Exemplarily, the terminal may access the target cell via random access or random access-free mode. If the random access-free mode is used, the target DU may send downlink control information to the terminal based on the beam information. In the random access-free mode, the terminal may access the target cell via PUSCH based on the timing advance information in the LTM cell handover command in step S519, rather than via PRACH.

[0234] S523: The target DU sends an access success message to the CU.

[0235] Accordingly, the CU receives an access success message from the target DU.

[0236] The access success message may carry the identifier of the target cell. Exemplarily, after detecting the access of the terminal, the target DU sends the access success message to the CU.

[0237] S524, the terminal sends an RRC reconfiguration complete message to the target DU;

[0238] Accordingly, the target DU receives an RRC reconfiguration complete message from the terminal.

[0239] S525, the target DU sends an UL RRC message to the CU;

[0240] Accordingly, the CU receives the UL RRC message from the target DU.

[0241] The UL RRC message includes an RRC reconfiguration complete message.

[0242] S526: The CU sends a UE context release command message to the source DU.

[0243] Accordingly, the source DU receives a UE context release command message from the CU.

[0244] The UE context release command message is used to instruct the release of resources of the candidate cell of the source DU.

[0245] S527, the source DU sends a UE context release complete message to the CU;

[0246] Accordingly, the CU receives a UE context release complete message from the source DU.

[0247] Based on the above solution, the terminal can switch from the source DU under the CU of the base station to the candidate DU under the CU, complete the LTM switching, avoid the interruption of communication service due to the deterioration of the signal quality of the terminal's serving cell, and ensure the user service experience.

[0248] In 5G systems, when a terminal is in an RRC-connected state, mobility triggers a handover. For example, before the signal quality of the terminal's serving cell becomes unavailable for normal communication, the terminal can switch to a neighboring cell with better signal quality, thereby providing continuous, uninterrupted communication. However, research has found that for LTM handover scenarios, there is no solution for inter-base station handover, where the terminal switches from one base station's cell to another.

[0249] In view of this, an embodiment of the present application provides a communication method and a communication device, which can enable a terminal to implement cell switching between base stations in an LTM switching scenario, and at the same time reduce the cell switching delay based on advance synchronization.

[0250] The communication method and apparatus provided by the present application are further described below in conjunction with the accompanying drawings. It is understandable that the present application uses the first node (e.g., MN), the second node (e.g., candidate SN) and the third node (e.g., source SN) as examples of the execution subjects of the interaction diagram, but the present application does not limit the execution subjects of the interaction diagram. For example, the method executed by any node in the present application can also be implemented by a module in the node (e.g., a circuit, a chip or a chip system, etc.), or a logical node, a logical module or software that can implement all or part of the network functions.

[0251] Figure 6 is a flow chart of a communication method provided in an embodiment of the present application. As shown in Figure 6, the method includes the following steps.

[0252] S610: A first node sends a first message to a second node. Correspondingly, the second node receives the first message from the first node.

[0253] Exemplarily, the first message is used to request that the second node be added as a candidate secondary node of the terminal, and the first message may be a SN ADDTION REQUEST message.

[0254] The first message includes first identification information, and in this application, the first identification information is used to request early synchronization configuration for the first identification information. For example, the first identification information may be a random access channel identifier RACH ID1 or a DU identifier 1 of the third node.

[0255] It should be understood that the early synchronization configuration is used for early synchronization of the terminal. The early synchronization means that the terminal performs a synchronization process before receiving a switching command. The synchronization process can be a random access process. Early synchronization can reduce the delay of the terminal's primary and secondary cell switching.

[0256] Optionally, the first message also includes one or more of the following: first indication information, identification information of K cells, identification of the first node, identification of the third node, or second identification information, wherein the K cells include the first cell, the first cell belongs to the second node, and K is an integer greater than 1, and the specific meaning is described as follows.

[0257] (1) first indication information;

[0258] For example, the first indication information may be LTM indication information, and the first indication information is used to request, with respect to the LTM, that the second node be added as a candidate secondary node of the terminal.

[0259] Optionally, the first indication information may be LTM initiated, and is used to indicate to the second node that LTM configuration for the second node has been initiated. Optionally, the first indication information may be determined based on the second indication information carried in the third message.

[0260] (2) Identification information of K cells;

[0261] The identification information of the K cells is used to recommend (or suggest) the K cells to the second node as cells (primary secondary cells, PSCells) of the terminal.

[0262] For example, the identification information of the cell includes at least one of the following: a cell global identifier (CGI) and a physical cell identifier (PCI).

[0263] It should be understood that the K cells belong to the second node.

[0264] (3) the identifier of the first node;

[0265] For example, the identifier of the first node can identify the first node, that is, the sender of the first message. The identifier of the first node can be the ID of the first node (such as MN Global NG-RAN Node ID), the address information of the first node, or other forms of expression for identifying the first node.

[0266] (4) second identification information;

[0267] In this application, the second identification information is used to request the second node to configure early synchronization for the second identification information, and the second identification information is different from the first identification information. For example, the second identification information can be a random access channel identifier RACH ID2, or a DU identifier or other identifier of the third node.

[0268] That is, the first message may include one or more identification information, and the multiple identification information is used to request advance synchronization configuration for the multiple identification information.

[0269] (5) The identifier of the third node;

[0270] For example, the identifier of the third node can identify the third node, and the identifier of the third node can be the ID of the third node (such as Global NG-RAN Node ID and / or S-NG-RAN node UE XnAP ID), the address information of the third node, or other forms of expression for identifying the third node.

[0271] In one implementation, the second node can determine, based on the identifier of the third node carried in the first message, that the first early synchronization configuration corresponding to the first identification information is assigned to the third node, or in other words, the second node assigns the first early synchronization configuration corresponding to the first identification information to the third node.

[0272] Optionally, before executing step S610, the first node obtains (or determines) the first message, that is, the method further includes the following step S601.

[0273] S601: A first node obtains (or determines) a first message.

[0274] In a first example, the first node receives a third message from a third node, and then in response to the third message, the first node obtains (or determines) the first message.

[0275] It should be understood that the third message in this implementation may be determined by the third node, and the specific implementation may include the following steps S630 and S640.

[0276] S630: The third node determines the third message.

[0277] S640: The third node sends a third message to the first node.

[0278] Accordingly, the first node receives a third message from the third node.

[0279] In one implementation, the third node may determine to initiate LTM configuration for the second node, i.e., determine a third message, based on a measurement report from the terminal device. The measurement report includes a measurement result of a neighboring cell (e.g., a cell of the second node, including the first cell), and the measurement result may indicate a signal quality of the neighboring cell, e.g., the signal quality is greater than or equal to a preset threshold.

[0280] The third message is used to trigger the first node to request the second node to add the second node as a candidate secondary node of the terminal. For example, the third message may be an SN CHANGE REQUIRED message.

[0281] It should be understood that "used to trigger" can be understood as: in response to the third message, the first node executes the above step S610. For example, the third message serves as a trigger condition, so that after receiving the third message, the first node sends the first message to the second node, i.e., requests the second node to add the second node as a candidate secondary node for the terminal.

[0282] Optionally, after receiving the third message, the first node can also determine in combination with local policies (for example, inter-station reachability) that the second node can be a candidate auxiliary node for the terminal, and / or, based on the fact that the second node can establish multiple connections with the first node, the first node sends the first message to the second node.

[0283] Exemplarily, the third message may include the identifier of the second node and the first identifier information, the specific meaning of which is described below.

[0284] (1) identification information of the second node;

[0285] The identification information of the second node may identify the second node, and may be the ID of the second node (such as SN Global NG-RAN Node ID), the address information of the second node, or other forms of expression for identifying the second node.

[0286] Optionally, when determining the third message, the third node may include identifiers of multiple nodes, and the identifiers of the multiple nodes are used to trigger the first node to request the multiple nodes to add the multiple nodes as candidate auxiliary nodes of the terminal, wherein the multiple nodes include the second node.

[0287] In one implementation, the first node may determine, based on the identification information of the second node carried in the third message, that the second node can serve as a candidate secondary node of the terminal, and then send the first message to the second node in step S610.

[0288] (2) first identification information;

[0289] In the present application, the first identification information is used to request an advance synchronization configuration for the first identification information, and the first identification information is different from the identification information of the second node.

[0290] For example, the first identification information may be a random access channel identifier RACH ID1, or a DU ID or other ID of the third node, see the relevant description of S610.

[0291] In one implementation, the first node may send the first identification information to the second node in step S610 based on the first identification information carried in the third message, so as to request the second node to provide an advance synchronization configuration for the first identification information.

[0292] Optionally, the third message further includes one or more of the following: second identification information, an identification of a third node, second indication information, or identification information of K cells, where the K cells include the first cell, the first cell belongs to the second node, and K is a positive integer, with a specific meaning as described below.

[0293] (1) Second identification information;

[0294] For example, the second identification information is used to request the second node to configure the early synchronization for the second identification information. The second identification information is different from the first identification information. For example, the second identification information can be a random access channel identifier RACH ID2 or other ID. For details, see the explanation of S610.

[0295] It should be noted that the first identification information and the second identification information may be determined according to the DU topology of the third node. Different DUs of different third nodes may have different corresponding identification information, that is, the second identification information is different from the first identification information.

[0296] That is, when determining the third message, the third node may include one or more identification information, where the multiple identification information is used to request advance synchronization configuration for multiple identification information, wherein the multiple identification information includes the first identification information.

[0297] In one implementation, the first node may determine to request the second node to obtain the advance synchronization configuration corresponding to the second identification information based on the second identification information carried in the third message. Therefore, the second identification information may also be carried in the above step S610.

[0298] (2) The identifier of the third node;

[0299] For example, the identifier of the third node can identify the third node, that is, the sender of the third message. The identifier of the third node can be the ID of the third node (such as Global NG-RAN Node ID and / or S-NG-RAN node UE XnAP ID), the address information of the third node, or other forms of expression for identifying the third node.

[0300] In one implementation, after the first node receives the first early synchronization configuration corresponding to the first identifier and / or the third early synchronization configuration corresponding to the second identifier information from the second node, it can send the first early synchronization configuration and / or the third early synchronization configuration to the third node based on the identifier of the third node.

[0301] (3) second instruction information;

[0302] For example, the second indication information may be LTM indication information, where the second indication information is used to indicate that, for LTM, the first node is triggered to request the second node to add the second node as a candidate secondary node of the terminal.

[0303] Optionally, the second indication information may also be LTM initiated, used to indicate to the first node that LTM configuration for the second node has been initiated.

[0304] In one implementation, the first node can determine, based on the first indication information carried in the third message, that it requests the second node to be added as a candidate auxiliary node of the terminal for LTM, and then send the first indication information to the second node in step S610. The first indication information can be determined based on the second indication information.

[0305] (4) Identification information of K cells;

[0306] The identification information of the K cells is used to recommend (or suggest) to the first node that the K cells be used as the PSCells of the terminal. For details, see the relevant description of S610.

[0307] For example, the identification information of the cell includes at least one of the following: a cell global identity CGI, or a physical cell identity PCI.

[0308] In one implementation, the third node may determine, based on the signal quality of the K cells, for example, if the signal quality of the K cells is greater than or equal to a preset threshold, that the K cells can be recommended, and include the information in the third message. Furthermore, in step S610, the first node transmits identification information of the K cells to the second node for the second node to select a cell for the terminal.

[0309] In a second example, the first node may determine the first message by itself.

[0310] In one implementation, the first node determines the first message when determining to initiate LTM configuration for the second node.

[0311] Optionally, the first node may determine the first message according to the measurement report from the terminal, and request the second node to use the second node as a candidate secondary node of the terminal.

[0312] The parameters included in the first message and their specific interpretations can be found in the description of step S610 above and will not be described again here.

[0313] S620: In response to the first message, the second node sends a second message to the first node. Correspondingly, the first node receives the second message from the second node.

[0314] Exemplarily, the second message is used to confirm adding the second node as a candidate secondary node of the terminal, and the second message may be a SN ADDTION REQUEST ACKNOWLEDGE message.

[0315] In one implementation, after receiving the second message, the second node determines whether to accept the candidate auxiliary node as the terminal. For example, the second node can determine to accept the candidate auxiliary node of the terminal based on factors such as the current link communication quality is good and / or the current battery capacity of the second node is sufficient.

[0316] Exemplarily, the second message includes a first early synchronization configuration corresponding to the first identification information.

[0317] In one implementation, in response to the first identification information in the first message, the second node sends an early synchronization configuration corresponding to the first identification information to the first node, such as a first early synchronization configuration, that is, the first early synchronization configuration corresponds to the first identification information.

[0318] It should be noted that the first early synchronization configuration is assigned by the second node to the third node and can be used for early synchronization of the terminal. For example, the second node determines to assign the first early synchronization configuration corresponding to the first identification information to the third node based on the first identification information carried in the first message and the identification of the third node.

[0319] It should be understood that the first early synchronization configuration may be random access configuration #1 (such as random access channel configuration RACH config 1, RACH config 1 corresponds to RACH ID 1), the random access configuration #1 indicates random access resource #1, and the random access resource #1 is used to perform the early synchronization process.

[0320] Optionally, the second message also includes one or more of the following: identification information of the accepted candidate primary and secondary cells, identification of the third node, a second early synchronization configuration, a lower layer RRC configuration corresponding to the accepted candidate primary and secondary cells, or a third early synchronization configuration, the specific meanings of which are described below.

[0321] (1) Identification information of the accepted candidate primary and secondary cells;

[0322] The received identification information of the candidate primary and secondary cells is used to identify the cell of the second node, for example, the first cell, that is, the primary and secondary cells of the terminal can be switched to the first cell, wherein the first cell belongs to the second node.

[0323] In one implementation, in response to the identification information of the K cells carried in the first message, the second node determines whether to accept one or more of the K cells recommended by the first node as candidate secondary nodes of the terminal. For example, the second node can select the first cell from the K cells as the candidate primary and secondary cell of the terminal. Optionally, the first cell is one of the K cells with relatively abundant communication resources.

[0324] Further, the second node may send identification information of the first cell, such as Cell A ID, to the first node according to the identifier of the first node carried in the first message.

[0325] It should be noted that the first early synchronization configuration carried in the above-mentioned second message can be regarded as the configuration of the first cell, and the first early synchronization configuration is used for early synchronization of the first cell.

[0326] (2) The identifier of the third node;

[0327] For example, the identifier of the third node can identify the third node, which can be the ID of the third node (such as Global NG-RAN Node ID and / or S-NG-RAN node UE XnAP ID), the address information of the third node, or other forms of expression for identifying the third node.

[0328] (3) Second advance synchronization configuration;

[0329] The second early synchronization configuration indicates random access resource #2 (eg, random access root sequence Root Sequence), and the random access resource #2 is used to perform an early synchronization process.

[0330] It should be understood that the second early synchronization configuration is assigned to the terminal by the second node, that is, terminal #1 can perform random access to the first cell based on the random access resource #2. The second early synchronization configuration may be the same as or different from the first early synchronization configuration, and this application does not limit this.

[0331] Exemplarily, when the second early synchronization configuration is the same as the first early synchronization configuration, the first early synchronization configuration or the second early synchronization configuration includes one or more of the following: random access resources, random access preamble index or random access root sequence Root Sequence, that is, the second node can assign the same random access configuration to the third node and the terminal.

[0332] Exemplarily, when the second early synchronization configuration is different from the first early synchronization configuration, the first early synchronization configuration may include one or more of the following: a first random access resource and / or a random access preamble index, and the second early synchronization configuration includes one or more of the following: a second random access time-frequency resource and / or a random access root sequence Root Sequence, wherein the first random access resource and the second random access resource are different.

[0333] In one implementation, the third node sends a physical downlink control channel (PDCCH) command to the terminal using the random access resources indicated by the first early synchronization configuration. In response to the PDCCH command, the terminal sends a first random access preamble to the second node based on the obtained random access resources and the second early synchronization configuration, thereby completing early synchronization.

[0334] (4) Third advance synchronization configuration;

[0335] For example, assuming that the first message carries second identification information, the second node may further assign a third early synchronization configuration to the terminal based on the second identification information, i.e., the third early synchronization configuration corresponds to the second identification information. It should be noted that the third early synchronization configuration is assigned by the second node to the third node and can be used for early synchronization of the terminal.

[0336] That is, the first message sent by the first node to the second node may carry multiple identification information. Then, in response to the first message, the second node may send multiple advance synchronization configurations corresponding to the multiple identification information to the first node.

[0337] Optionally, different early synchronization configurations corresponding to different identification information indicate different random access resources.

[0338] (5) Lower layer RRC configuration corresponding to the accepted candidate primary and secondary cells;

[0339] Exemplarily, it includes but is not limited to: TCI state configuration, random access channel RACH configuration, or CSI report configuration.

[0340] Optionally, based on the above step S620, the method further includes the following steps S602-S603.

[0341] S602: The first node sends a fourth message to the third node.

[0342] Accordingly, the third node receives the fourth message from the first node.

[0343] Exemplarily, the fourth message may be a SN MODIFICATION REQUEST message.

[0344] The fourth message includes a first early synchronization configuration and its corresponding first identification information, and the first early synchronization configuration is used to indicate random access resource #1.

[0345] S603: The third node triggers early synchronization of the first cell to the terminal through the second cell based on the first early synchronization configuration.

[0346] It should be understood that the second cell belongs to the third node, and the second cell is the current serving cell of the terminal.

[0347] In one implementation, the third node determines that the first early synchronization configuration is associated with the second cell, and then the third node can initiate early synchronization for the first cell to the terminal through the second cell based on the first early synchronization configuration. The third node determines that the first early synchronization configuration is associated with the second cell, including: the third node receives early synchronization configurations corresponding to multiple identification information from the first node (for example, the first early synchronization configuration and the third early synchronization configuration), and determines the cell of the third node associated with the early synchronization configurations corresponding to the multiple identification information (for example, the first early synchronization configuration is associated with the second cell). According to the terminal identification information in the fourth message, it is determined that the first early synchronization configuration is related to the terminal. Based on the above step S620, it can be known that the first early synchronization configuration is the configuration of the first cell, which is used for the terminal to perform early synchronization for the first cell. At the same time, the second cell is the primary and secondary cell currently served by the terminal, and the third node can initiate early synchronization for the first cell to the terminal through the second cell.

[0348] Optionally, the fourth message may further include a second early synchronization configuration for indicating random access resource #2. It should be noted that the second early synchronization configuration is allocated to the terminal by the second node and can be used for early synchronization of the terminal.

[0349] In one implementation, if the fourth message includes the second early synchronization configuration, the method 600 further includes the following steps S604-S606.

[0350] S604: The third node encapsulates the second advance synchronization configuration.

[0351] The specific implementation of encapsulation includes: encapsulating based on the format of the SN, for example, encapsulating the second early synchronization configuration into the SN RRC Reconfiguration message.

[0352] S605: The third node sends a ninth message to the first node.

[0353] Correspondingly, the first node receives the ninth message from the third node.

[0354] The ninth message includes the encapsulated second early synchronization configuration, and the encapsulated second early synchronization configuration is used for early synchronization of the terminal with respect to the first cell.

[0355] Exemplarily, the ninth message may be a SN MODIFICATION REQUESTACKNOWLEDGE message.

[0356] S606: In response to the ninth message, the first node may send a tenth message to the terminal.

[0357] Accordingly, the terminal receives the tenth message from the first node.

[0358] The tenth message includes the encapsulated second early synchronization configuration. Exemplarily, the tenth message may be an SN RRC reconfiguration message, which includes the encapsulated second early synchronization configuration.

[0359] Based on the above steps, the terminal obtains the encapsulated second early synchronization configuration, and based on the trigger request of the third node (for example, the PDCCH indication below) and the encapsulated second early synchronization configuration, performs the early synchronization process for the primary and secondary cells (for example, the first cell) with the second node.

[0360] The following describes an implementation method for early synchronization of the first cell between the terminal and the second node.

[0361] For example, in step S603 above, the third node may send a PDCCH command to the terminal based on the first early synchronization configuration. The PDCCH command includes random access resource #1, that is, the first random access preamble and / or the first random access time-frequency resource. The resources indicated by the first early synchronization configuration include the random access resource #1. In response to the PDCCH command, the terminal sends the first random access preamble to the second node based on the first random access time-frequency resource and the second early synchronization configuration, thereby completing early synchronization.

[0362] Accordingly, after receiving the random access preamble, the second node may determine the TA of the first cell based on the random access preamble and determine the association between the random access preamble and the first identification information. For example, the second node may calculate the TA value of the terminal based on the reception time of the random access preamble. In other words, the TA of the first cell is determined during the early synchronization process of the first cell.

[0363] Optionally, after the terminal and the second node perform an early synchronization process of the first cell, the second node may send the TA of the first cell determined in the early synchronization process of the first cell to the terminal, so that the terminal can subsequently access the first cell in a random access RACH (RACH-less) manner, thereby reducing the random access delay, that is, the method 600 also includes the following steps S607-S609.

[0364] S607: The second node may send a fifth message to the first node.

[0365] Correspondingly, the first node receives the fifth message from the second node.

[0366] Exemplarily, the fifth message may be a 1st TA INFORMATION TRANSFER message.

[0367] The fifth message includes the TA of the first cell, the identifier of the third node, and the first identifier information. It should be noted that the TA of the first cell is associated with the first identifier information, and the TA of the first cell is associated with the identifier of the third node.

[0368] It should be understood that the TA of the first cell is determined during the process of early synchronization between the second node and the terminal for the first cell, which means that the terminal can access the first cell in a random access-free manner based on the TA when receiving the cell switching command, thereby reducing the random access delay.

[0369] S608: In response to the fifth message, the first node sends a sixth message to the third node. Accordingly, the third node receives the sixth message from the first node.

[0370] Exemplarily, the sixth message may be a 2nd TA INFORMATION TRANSFER message.

[0371] The sixth message includes the TA and first identification information of the first cell.

[0372] In one implementation, the first node sends the TA and first identification information of the first cell to the third node according to the identification of the third node carried in the fifth message.

[0373] S609: The third node determines, based on the sixth message, that the TA of the first cell is associated with the terminal, and then sends the TA of the first cell to the terminal.

[0374] In one implementation, the third node determines a corresponding first early synchronization configuration based on the first identification information in the sixth message, where the first early synchronization configuration was previously used for early synchronization of the terminal, thereby determining the terminal associated with the TA of the first cell. The first early synchronization configuration may include multiple pre-random access indices, such as random access preamble #1 and random access preamble #2. Assuming that random access preamble #1 is assigned to the terminal, the third node may determine, based on the terminal sending random access preamble #1, that the first early synchronization configuration is associated with the terminal, thereby determining that the TA of the first cell is associated with the terminal, and then sending the TA of the first cell to the terminal.

[0375] Optionally, before sending the TA of the first cell to the terminal, the third node receives a measurement report reported by the terminal and determines to initiate a cell switching command based on the measurement report. For example, the third node may send a switching command (such as a Cell switch command MAC CE) to the terminal via a MAC CE. The switching command is used to instruct the primary and secondary cells of the terminal to switch to the first cell. The switching command includes the TA of the first cell and an identifier corresponding to the first cell (for example, an LTM configuration identifier).

[0376] Correspondingly, the terminal can determine that early synchronization has been performed on the first cell according to the TA of the first cell and the identifier corresponding to the first cell in the handover command, and can then switch to the first cell in a random access-free manner.

[0377] Optionally, after the third node sends a switching command to the terminal, the third node can notify the second node that it has initiated a switching command for the first cell to the terminal, so that the second node can monitor the terminal to access the first cell in a random access-free manner, that is, the method 600 also includes the following steps S611-S612.

[0378] S611: The third node sends a seventh message to the first node.

[0379] Correspondingly, the first node receives the seventh message from the third node.

[0380] Exemplarily, the seventh message may be a 1st Cell Switch Notify message.

[0381] The seventh message is used to indicate that the switching command in step S609 has been sent to the terminal.

[0382] Exemplarily, the seventh message includes the identifier of the second node and identifier information of the first cell.

[0383] Optionally, the first node determines the configuration of the current MN according to the identification information of the first cell, that is, different cells of the second node correspond to different MN configurations.

[0384] S612: In response to the seventh message, the first node sends an eighth message to the second node.

[0385] Accordingly, the second node receives the eighth message from the first node.

[0386] Exemplarily, the eighth message may be a 2nd Cell Switch Notify message.

[0387] The eighth message is used to indicate that the switching command has been sent to the terminal.

[0388] Exemplarily, the eighth message includes identification information of the first cell.

[0389] In one implementation, the first node may send the eighth message to the second node based on the second node identifier in the seventh message, and at the same time notify the second node that it has sent a switching command for the first cell to the terminal based on the identifier of the first cell in the seventh message.

[0390] Correspondingly, after receiving the eighth message, the second node may monitor whether the terminal accesses the first cell in RACH-less mode, and after determining that the terminal successfully accesses the first cell, it indicates that the primary and secondary cells of the terminal are the first cell.

[0391] Optionally, the second node may also schedule the terminal to access the first cell in a RACH-less manner to complete the handover between the primary and secondary cells of the terminal.

[0392] Optionally, after completing the handover of the first cell, the terminal may send an RRC reconfiguration complete message (eg, SN reconfiguration complete message) to the second node. It should be understood that after completing the handover of the primary and secondary cells of the terminal, the terminal may transmit signaling and / or data with the second node.

[0393] Based on the above solution, in the LTM handover scenario, by obtaining the first advance synchronization configuration corresponding to the first identification information, advance synchronization for the first cell can be achieved. After the terminal receives the handover command, it can access the first cell in a random access-free manner, thereby reducing the terminal's primary and secondary cell handover delay. Before the terminal's primary and secondary cell handover, the terminal can transmit user plane data between the first node and the third node respectively. After the terminal's primary and secondary cell handover is completed, the terminal can transmit user plane data between the first node and the second node respectively, avoiding service drops or interruptions and ensuring the user's service experience.

[0394] Figure 7 is a flow chart of a communication method 700 provided in an embodiment of the present application. As shown in Figure 7, the first node is MN, the second node is candidate SN (including candidate SN-CU and candidate SN-DU), and the third node is source SN (including source SN-CU and source SN-DU) as the execution body for explanation, wherein, in the DC scenario, the terminal is connected to the MN and the source SN respectively, and the source SN is the secondary node currently serving the terminal. After the primary and secondary cell switching of the terminal is completed, the terminal is connected to the MN and the candidate SN respectively, and the candidate SN is the secondary node serving the terminal. The method includes the following multiple steps.

[0395] It should be understood that the method 700 shown in FIG7 can be regarded as a specific implementation of the method shown in FIG6. The relevant description of the embodiment shown in FIG6 is also applicable to this implementation. FIG7 and FIG6 may use the same or similar technical means. The content described in the embodiment shown in FIG6 will not be repeated in FIG7.

[0396] S701: The terminal sends a measurement report to the MN (ie, an example of the first node).

[0397] Accordingly, the MN receives the measurement report from the terminal.

[0398] The measurement report includes L3 measurement results, such as measurement results of neighboring cells (for example, the cell of the second node, including the first cell), and the measurement results can indicate the signal quality of the neighboring cells. The neighboring cells refer to cells that may be switched after the terminal moves (for example, the first cell).

[0399] S702: The MN sends a measurement report to the source SN-CU (ie, an example of the third node).

[0400] Accordingly, the source SN-CU receives the measurement report from the MN.

[0401] The measurement report includes the L3 measurement result reported by the terminal.

[0402] S703: The source SN-CU determines to initiate LTM configuration for the candidate SN according to the measurement report.

[0403] Exemplarily, the source SN-CU determines to initiate LTM configuration for the candidate SN based on the measurement result of the neighboring cell carried in the measurement report (for example, the measurement result indicates that the signal quality of the neighboring cell is high).

[0404] S704: The source SN-CU sends an SN change request message (ie, an example of the third message) to the MN.

[0405] Accordingly, the MN receives the SN change request message from the source SN-CU.

[0406] Exemplarily, the SN change request message may be an SN CHANGE REQUIRED message, which is used to trigger the MN to request the candidate SN to add the candidate SN as a candidate secondary node of the terminal. For the specific meaning of "used to trigger", please refer to the relevant description of the above method 600.

[0407] Exemplarily, the SN change request message may include: an identifier of the candidate SN (e.g., Global NG-RAN Node ID) and at least one RA identification information (e.g., RA identification information #1, such as RACH ID 1). For specific explanations, please refer to the relevant descriptions of steps S630-S640 of the above method 600.

[0408] Optionally, the SN change request message may also include one or more of the following: the identification of the source SN, LTM information #1 (i.e., an example of the second indication information), or identification information of the recommended K cells (e.g., Cell A and Cell B). For specific explanations, please refer to the relevant descriptions of steps S630-S640 of the above method 600.

[0409] It should be noted that the above steps may be a third message determined by the source SN-CU and sent to the MN, which is used to trigger the MN to request the candidate SN to add the candidate SN as a candidate secondary node of the terminal, that is, to execute the following step S705.

[0410] Optionally, the MN may autonomously request the candidate SN to be added as a candidate secondary node of the terminal, for example, the MN receives a measurement report reported by the terminal, and determines to request the candidate SN to be added as a candidate secondary node of the terminal according to the measurement report, i.e., executes the following step S705.

[0411] Optionally, the source SN-CU may allocate different RA identification information according to different source SN-DUs. For example, one DU corresponds to one RA identification information, and then one or more cells under the DU may correspond to the one RA identification information. Since the one RA identification information corresponds to one or more early synchronization configurations, the one or more early synchronization configurations may be associated with the one or more cells. For example, one cell may correspond to one early synchronization configuration, that is, one cell corresponds to one random access resource, and the early synchronization configurations corresponding to different cells may be the same or different, that is, the random access resources corresponding to different cells may be the same or different. For another example, one or more cells under multiple DUs may also correspond to one RA identification information, and the one RA identification information may correspond to one or more early synchronization configurations. Then, one or more cells under multiple DUs may correspond to one or more early synchronization configurations, that is, one or more cells under multiple DUs correspond to one or more random access resources, and the random access resources corresponding to different cells may be the same or different.

[0412] S705 : The MN sends an SN adding request message (ie, an example of the first message) to the candidate SN-CU (ie, an example of the second node).

[0413] Accordingly, the candidate SN-CU receives the SN add request message from the MN.

[0414] Exemplarily, the SN addition request message may be an SN ADDTION REQUEST message, used to request that a candidate SN be added as a candidate secondary node of the terminal.

[0415] Exemplarily, the SN adding request message may include at least one RA identification information, used to request advance synchronization configuration for the at least one RA identification information.

[0416] Optionally, the SN add request message may also include one or more of the following: LTM information #2 (i.e., an example of the first indication information), identification information of K cells (e.g., Cell A and Cell B), identification of the source SN node, or identification of the MN. For specific explanations, please refer to the relevant description of step S610 of the above method 600.

[0417] Optionally, under the CU-DU separation architecture of the candidate SN, the method 700 further includes the following steps S706-S707.

[0418] S706: The candidate SN-CU sends a UE context establishment request message to the candidate SN-DU.

[0419] Accordingly, the candidate SN-DU receives the UE context establishment request message from the candidate SN-DU.

[0420] The UE context establishment request message is used to request the candidate SN-DU to establish a UE context for LTM.

[0421] Exemplarily, the UE context establishment request message may include one or more of the following: at least one RA identification information (e.g., RACH ID1), LTM information #2, identification information of the recommended K cells (e.g., Cell A ID), or an MN identifier. For specific explanations, please refer to the relevant description of step S610 of the above method 600.

[0422] S707: The candidate SN-DU sends a UE context establishment response message to the candidate SN-CU.

[0423] Accordingly, the candidate SN-CU receives the UE context establishment response message from the candidate SN-DU.

[0424] Exemplarily, after receiving the UE context establishment request message, the candidate SN-DU determines whether to accept the recommended or suggested K cells as candidate primary and secondary cells of the terminal. If the candidate SN-DU accepts the above request message, the candidate SN-DU sends a UE context establishment response message to the candidate SN-CU.

[0425] The UE context establishment response message may include a CFRA configuration. The CFRA configuration may be a CFRA configuration of one or more candidate cells (e.g., Cell A, an example of the first cell) accepted by the candidate SN. The CFRA configuration includes at least one random access configuration (e.g., random access configuration #1, an example of the first early synchronization configuration), and the at least one random access configuration is a random access configuration for the same candidate primary and secondary cell. For example, if the candidate SN accepts Cell A as the candidate primary and secondary cell of the terminal, then random access configuration #1 is the random access configuration of Cell A, which is used for the terminal to access Cell A through the random access resources indicated by random access configuration #1.

[0426] It should be understood that the at least one random access configuration has a corresponding relationship with the at least one RA identifier information, and one RA identifier may correspond to one random access configuration, for example, RACH ID1 corresponds to RACH Config 1, and RACH ID2 corresponds to RACH Config 2; or, one RA identifier may correspond to multiple random access configurations, for example, RACH ID1 corresponds to RACH Config 1 and RACH Config 2. This application is not limited to this.

[0427] It should also be understood that when the candidate SN accepts multiple candidate primary and secondary cells (for example, Cell A and Cell B), the CFRA configuration includes the random access configuration of Cell A and the random access configuration of Cell B. In other words, different candidate primary and secondary cells have their own random access configurations.

[0428] Exemplarily, random access configuration #1 (e.g., random access channel configuration RACH config 1, RACH config 1 corresponds to RACH ID 1) indicates a random access resource, where the random access resource includes one or more of the following:

[0429] (1) Random access preamble index;

[0430] For example, the random access preamble index may be at least one SSB index (index) for a candidate primary and secondary cell (e.g., Cell A), and / or a non-contention random access preamble index corresponding to the SSB index. During the random access process, the terminal may send a random access preamble code to the second node based on the random access preamble index to achieve uplink early synchronization.

[0431] (2) Random access to time-frequency resources;

[0432] For example, the random access resources include at least one of random access root sequence information, random access window information, or contention resolution timer information. During the random access process, the terminal can use the random access time-frequency resources to send a random access preamble code to the candidate SN-CU to achieve uplink early synchronization.

[0433] It should be understood that the candidate SN-CU can allocate respective early synchronization configurations for different candidate primary and secondary cells, and different early synchronization configurations indicate corresponding random access resources for the terminal to use random access resources to perform early synchronization of the corresponding candidate primary and secondary cells.

[0434] Optionally, the random access resources indicated by different advance synchronization configurations may be the same or different, and this application does not limit this.

[0435] S708: The candidate SN-CU sends an SN addition response message (ie, an example of the second message) to the MN.

[0436] Accordingly, the MN receives an SN addition response message from the candidate SN-CU.

[0437] The SN addition response message may be an SN ADDTION REQUEST ACKNOWLEDGE message, which is used to confirm adding the candidate SN as a candidate secondary node of the UE.

[0438] The SN addition response message includes at least one random access configuration (e.g., random access configuration #1, i.e., the first early synchronization configuration). It should be noted that random access configuration #1 is assigned by the candidate SN to the source SN and is used for early synchronization of the UE. Regarding the source SN triggering the early synchronization process for the candidate primary and secondary cells (e.g., Cell A) to the terminal through the cell of the source SN based on early synchronization configuration #1, reference may be made to the relevant description of step S603 of the above method 600.

[0439] Optionally, the random access resources indicated by different early synchronization configurations corresponding to different identification information are different.

[0440] Exemplarily, the random access configuration #1 indicates random access resource #1, for example, including one or more of a random access preamble index, a random access time-frequency resource, random access root sequence information, random access window information, or contention resolution timer information. For specific explanations, reference may be made to the relevant description of the above method 600. It should be understood that the random access resources indicated by different random access configurations may be the same or different.

[0441] Optionally, the SN addition response message may also include one or more of the following: the identifier of the source SN, random access configuration #2 (i.e., an example of the second early synchronization configuration), the identification information of the candidate primary and secondary cells (e.g., Cell A) accepted by the candidate SN-CU, and the lower-layer RRC configuration corresponding to the accepted candidate primary and secondary cells (e.g., at least one of the TCI state configuration, random access channel RACH configuration, or CSI report configuration). For specific explanations, please refer to the relevant description of step S620 of the above method 600.

[0442] Optionally, based on the above step S708, the MN may send the acquired random access configuration #1 to the source SN, that is, the method may further include the following step S709.

[0443] S709: The MN sends an SN modification request message (ie, an example of the fourth message) to the source SN-CU.

[0444] Accordingly, the source SN-CU receives the SN modification request message from the MN.

[0445] The SN modification request message may be an SN MODIFICATION REQUEST message, including at least one random access configuration (eg, random access configuration #1) and its corresponding at least one RA identification information (eg, RA identification information #1), wherein the random access configuration #1 is used to indicate the random access resource #1.

[0446] Optionally, the SN modification request message further includes random access configuration #2, which is used to indicate random access resource #2. It should be noted that random access configuration #2 is allocated to the terminal by the candidate SN and is used for early synchronization of the terminal.

[0447] Optionally, the SN modification request message further includes the random access configuration #2 and its corresponding RA identification information, such as RA identification information #1.

[0448] S710: The source SN-CU determines a correspondence between a cell of the source SN and at least one random access configuration.

[0449] Exemplarily, the source SN determines the correspondence between the source SN's cell (including the current serving cell) and at least one random access configuration issued by the candidate SN. For example, the source SN includes cell C and cell D, where cell C corresponds to random access configuration #1 (such as RACH config 1) and cell D corresponds to random access configuration 2 (such as RACH config 2). It should be understood that the correspondence determined by the source SN-CU in this step is used by the source SN-CU to subsequently send the TA of the candidate primary and secondary cells (such as Cell A) to the terminal.

[0450] Optionally, under the CU-DU separation architecture of the source SN, the method 700 also includes the following steps S711-S712.

[0451] S711: The source SN-CU sends a UE context establishment request message to the source SN-DU.

[0452] Accordingly, the source SN-DU receives the UE context establishment request message from the source SN-CU.

[0453] The UE context establishment request message is used to request the source SN-DU to establish a UE context for LTM.

[0454] Exemplarily, the UE context establishment request message may include one or more of the following: at least one RA identification information (e.g., RACH ID1), at least one random access configuration (e.g., random access configuration #1), identification information of a candidate primary and secondary cell (e.g., Cell A), or random access configuration #3. For specific explanations, please refer to the relevant description of the above method 600.

[0455] S712: The source SN-DU sends a UE context establishment response message to the source SN-CU.

[0456] Accordingly, the source SN-CU receives the UE context establishment response message from the source SN-DU.

[0457] Optionally, if the SN modification request message in the above step S709 carries random access configuration #2, the method 700 further includes the following steps S713-S716.

[0458] S713: The source SN-CU sends an SN modification response message (ie, an example of the ninth message) to the MN.

[0459] Accordingly, the MN receives an SN modification response message from the source SN-CU.

[0460] The SN modification response message includes the encapsulated random access configuration #2. For example, the SN modification response message may be a SN MODIFICATION REQUESTACKNOWLEDGE message.

[0461] Exemplarily, the source SN encapsulates the format of the SN, for example, encapsulates the random access configuration #2 into the SN RRC Reconfiguration message, and sends the encapsulated random access configuration #2 to the MN. The encapsulated random access configuration #2 is used by the terminal to perform early synchronization for the candidate primary and secondary cells (such as Cell A).

[0462] S714: The MN sends an RRC reconfiguration message (ie, an example of the tenth message) to the terminal.

[0463] Correspondingly, the terminal receives the RRC reconfiguration message from the MN.

[0464] The RRC reconfiguration message may be an RRC reconfiguration message including the encapsulated random access configuration #3.

[0465] S715: The terminal sends an RRC reconfiguration complete message to the MN.

[0466] Correspondingly, the MN receives an RRC reconfiguration complete message from the terminal.

[0467] S716: The MN sends an SN change notification message to the source SN-CU.

[0468] Accordingly, the source SN-CU receives the SN change notification message from the MN.

[0469] The SN change notification message includes an RRC reconfiguration completion message.

[0470] S717: The terminal and the candidate SN-CU perform an advance synchronization process for the candidate primary and secondary cells (eg, Cell A).

[0471] Among them, early synchronization includes early uplink synchronization or downlink synchronization. Based on the above steps, the terminal obtains the encapsulated early synchronization configuration #2, and can perform an early synchronization process for the primary and secondary cells (for example, the first cell) with the candidate SN based on the trigger request of the source SN (for example, the source SN sends a PDCCH indication to the UE) and the encapsulated early synchronization configuration #2. Among them, the process of early synchronization between the terminal and the candidate SN for the candidate primary and secondary cells (for example, Cell A) can refer to the relevant description of step S606 of the above method 600, which will not be repeated here.

[0472] It should be understood that, during the early synchronization process, the candidate SN-CU determines the TA of the candidate primary and secondary cells (eg, Cell A). At this time, the candidate SN-CU cannot determine which terminal the TA corresponds to.

[0473] Optionally, after the terminal and the candidate SN perform the early synchronization process of the candidate primary and secondary cells (e.g., Cell A), the candidate SN needs to send the TA of the candidate primary and secondary cells determined in the early synchronization process of the candidate primary and secondary cells (e.g., Cell A), so that the terminal can subsequently access the candidate primary and secondary cells (e.g., Cell A) in a RACH-less manner, thereby reducing the random access delay. That is, the method 700 also includes the following step S718, that is, the candidate SN sends the TA of the candidate primary and secondary cells to the MN, and then the MN sends it to the source SN, and then the source SN can send the TA of the candidate primary and secondary cells to the terminal when determining that the terminal performs cell switching.

[0474] S718: The candidate SN-CU sends a TA information transmission message #1 (ie, an example of the fifth message) to the MN.

[0475] Accordingly, the MN receives the TA information transfer message #1 from the candidate SN-CU. For example, the TA information transfer message #1 may be a 1st TA INFORMATION TRANSFER message.

[0476] Among them, the TA information transmission message #1 includes: the TA of the candidate primary and secondary cells (i.e., the first cell, such as Cell A), the identifier of the source SN, and at least one RA identifier information (such as RA identifier information #1). For specific interpretations, please refer to the relevant description of step S607 of the above method 600.

[0477] Optionally, the TA information transmission message #1 may also include: identification information of the candidate primary and secondary cells, and / or random access information of the random access preamble (for example, index information of the random access preamble and a radio access network temporary identifier (RA-RNTI), the RA-RNTI being determined based on the time-frequency resources of the random access preamble).

[0478] It should be noted that the TA of the candidate primary and secondary cells is associated with RA identification information #1, and the TA of the candidate primary and secondary cells is associated with the identification of the source SN. It should be understood that the TA of the candidate primary and secondary cells is determined during the process of early synchronization between the candidate SN node and the terminal for the candidate primary and secondary cells. This means that based on the TA, the terminal can access the candidate primary and secondary cells in a random access-free manner when receiving a cell handover command, thereby reducing random access latency.

[0479] S719: The MN sends a TA information transmission message #2 (ie, an example of the sixth message) to the source SN-CU.

[0480] Accordingly, the candidate SN-CU receives the TA information transfer message #2 from the MN. For example, the TA information transfer message #2 may be a 2nd TA INFORMATION TRANSFER message.

[0481] The TA information transmission message #2 includes: the TA of the candidate primary and secondary cells (eg, Cell A) and at least one RA identification information (eg, RA identification information #1). For specific explanations, refer to the description of step S608 of the above method 600.

[0482] Optionally, the TA information transmission message #2 may further include: identification information of candidate primary and secondary cells, and / or random access information of a random access preamble (eg, index information and RA-RNTI of the random access preamble).

[0483] Furthermore, the source SN-CU can determine that the TA of the candidate primary and secondary cell (e.g., Cell A) is associated with the terminal based on the TA information transmission message #2, and then send the TA of the candidate primary and secondary cell (e.g., Cell A) to the terminal. For the specific implementation method, please refer to the relevant description of step S609 of the above method 600.

[0484] S720: The terminal sends a measurement report to the source SN-CU.

[0485] Accordingly, the source SN-CU receives the measurement report from the terminal.

[0486] The measurement report includes an L1 measurement result, and the L1 measurement result includes a measurement result of a candidate primary and secondary cell (eg, Cell A).

[0487] S721: The source SN-CU determines to perform handover on the candidate primary and secondary cells according to the measurement report.

[0488] Exemplarily, the source SN-CU determines that the signal quality of the candidate primary and secondary cells (e.g., Cell A) is better based on the measurement results of the candidate primary and secondary cells (e.g., Cell A), and then determines to trigger the terminal to execute the RACH-less Cell switch command MAC CE based on the TA of the candidate primary and secondary cells (e.g., Cell A).

[0489] S722: The source SN-CU sends a cell switching command to the terminal.

[0490] Accordingly, the terminal receives a cell switching command from the source SN-CU.

[0491] In one implementation, the source SN-CU sends a Cell switch command MAC CE to the terminal. The MAC control element (MAC CE) is used to instruct the terminal to switch to the candidate primary and secondary cells (eg, Cell A) in a RACH-less manner.

[0492] Exemplarily, the MAC CE message may carry one or more of the following: the TA of the candidate primary and secondary cell (e.g., Cell A), the identifier of the candidate primary and secondary cell (e.g., Cell A), or the beam information of the candidate primary and secondary cell (e.g., Cell A) (e.g., TCI state identifier). The beam information is used for the terminal to receive downlink control information in a RACH-free manner, and the TA of the candidate primary and secondary cell is used to instruct the terminal to initiate a RACH-less cell handover for the candidate primary and secondary cell (e.g., Cell A) to reduce the cell handover delay.

[0493] Optionally, after the source SN sends a switching command to the terminal, the source SN may notify the candidate SN that it has initiated a switching command to the terminal for the candidate primary and secondary cells (e.g., Cell A), so that the candidate SN can monitor the terminal to access the candidate primary and secondary cells (e.g., Cell A) in a random access-free manner, that is, the method 700 also includes the following step S723.

[0494] S723: The source SN-CU sends a cell switching notification message #1 (ie, an example of the seventh message) to the MN.

[0495] Accordingly, the MN receives the cell switching notification message #1 from the source SN-CU.

[0496] The cell switch notification message #1 is used to indicate that a cell switch command has been sent to the terminal, and the cell switch notification message #1 may be a Cell Switch Notify message.

[0497] Exemplarily, the cell switching notification message #1 includes the identification information of the candidate primary and secondary cells (e.g., Cell A) and the identification of the candidate SN. Optionally, the MN can determine the current MN configuration based on the identification information of the candidate primary and secondary cells (e.g., Cell A), that is, different candidate SN cells correspond to different MN configurations.

[0498] Optionally, the cell switching notification message #1 may also include TCI state identification information of the candidate primary and secondary cells (eg, Cell A).

[0499] S724: The MN sends a cell switching notification message #2 (ie, an example of the eighth message) to the candidate SN-CU.

[0500] Accordingly, the candidate SN-CU receives the cell switching notification message #2 from the MN.

[0501] The cell switch notification message #2 is used to indicate that a cell switch command has been sent to the terminal, and the cell switch notification message #2 may be a Cell Switch Notify message.

[0502] Exemplarily, the cell switching notification message #2 includes identification information of candidate primary and secondary cells (eg, CellA).

[0503] Optionally, the cell switching notification message #2 may also include TCI state identification information of the candidate cell PSCell (eg, CellA).

[0504] S725: The candidate SN-CU detects that the terminal accesses the target cell.

[0505] For example, after receiving the cell switching notification message #2, the candidate SN-CU monitors whether the terminal accesses the candidate primary and secondary cell (e.g., CellA) through RACH-less. After the terminal successfully accesses the candidate primary and secondary cell (e.g., CellA), it indicates that the primary and secondary cell of the terminal is the candidate primary and secondary cell (e.g., CellA).

[0506] S726: The terminal sends an RRC reconfiguration completion message to the candidate SN-CU.

[0507] Accordingly, the candidate SN-CU receives an RRC reconfiguration completion message from the terminal, such as an RRC reconfiguration complete message.

[0508] It should be understood that after the handover of the candidate primary and secondary cells (e.g., Cell A) is completed, the candidate SN-CU may send user plane data to the terminal. In one example, the candidate SN-DU sends user plane data to the candidate SN-CU, the candidate SN-CU sends user plane data to the MN, and the MN then sends user plane data to the terminal.

[0509] Based on the above solution, for the LTM switching scenario, by obtaining the random access configuration corresponding to the RA identification information, early synchronization of the candidate primary and secondary cells can be achieved. After the terminal receives the cell switching command, it can access the candidate primary and secondary cells in a random access-free manner, thereby reducing the delay of the terminal's primary and secondary cell switching. Before the terminal's primary and secondary cells are switched, the terminal can transmit user-plane data between the MN and the source SN respectively. After the terminal's primary and secondary cell switching is completed, the terminal can use the TA of the candidate primary and secondary cells obtained in advance to transmit user-plane data between the MN and the candidate SN respectively, thereby avoiding service drops or interruptions and ensuring the user's service experience.

[0510] The communication method embodiment of the present application is described in detail above with reference to Figures 1 to 7 . The communication device embodiment of the present application will be described in detail below with reference to Figures 8 and 9 . It should be understood that the description of the device embodiment corresponds to the description of the method embodiment. Therefore, for portions not described in detail, reference can be made to the aforementioned method embodiment.

[0511] Figure 8 is a schematic diagram of a communication device provided in accordance with an embodiment of the present application. As shown in Figure 8, a communication device 1000 includes a processing module 1010 and a communication module 1020. The communication device 1000 may be a terminal side, such as a terminal, or a communication device applied to a terminal or used in conjunction with a terminal, capable of implementing a method executed by the terminal, such as a chip, a chip system or circuit, etc.; or, the communication device 1000 may also be a network side, such as a network device (which may be a first node, a second node or a third node), or a communication device applied to a network device or used in conjunction with a network device, capable of implementing a method executed by the network device, such as a chip, a chip system or circuit, a DU or a CU, etc.

[0512] The communication module 1020 may also be referred to as a transceiver module, transceiver, transceiver unit, or transceiver device. The processing module 1010 may also be referred to as a processor, processing board, processing unit, or processing device. Optionally, the communication module 1020 is configured to perform the sending and receiving operations of the first, second, or third node, or terminal in the above-described method. The device in the communication module 1020 that implements the receiving function may be considered a receiving unit, and the device in the communication module 1020 that implements the sending function may be considered a sending unit, i.e., the communication module 1020 includes a receiving unit and / or a sending unit. Optionally, the processing module 1010 is configured to implement the processing functions of the first, second, or third node, or terminal in the above-described method.

[0513] Exemplarily, the communication module 1020 is used to send a first message to the second node, the first message is used to request that the second node be added as a candidate auxiliary node of the terminal, the first message includes first identification information, and the first identification information is used to request early synchronization configuration from the second node; the communication module 1020 is also used to receive a second message from the second node, the second message is used to confirm that the second node is added as a candidate auxiliary node of the terminal, the second message includes a first early synchronization configuration, and the first early synchronization configuration corresponds to the first identification information.

[0514] Exemplarily, the communication module 1020 is used to receive a first message from the first node, the first message is used to request that the second node be added as a candidate auxiliary node of the terminal, the first message includes first identification information, and the first identification information is used to request early synchronization configuration; the communication module 1020 is also used to send a second message to the first node, the second message is used to confirm that the second node is added as a candidate auxiliary node of the terminal, the second message includes a first early synchronization configuration, and the first early synchronization configuration corresponds to the first identification information.

[0515] Exemplarily, the processing module 1010 is used to determine a third message, the third message including the identifier of the second node and the first identifier information, and the third message is used to trigger the first node to request the second node to perform an advance synchronization configuration for the first identifier information; the communication module 1020 is used to send the third message to the first node.

[0516] In addition, it should be noted that the aforementioned communication module and / or processing module can be implemented by a virtual module, for example, the processing module can be implemented by a software functional unit or a virtual device, and the communication module can be implemented by a software function or a virtual device. Alternatively, the processing module or the communication module can also be implemented by a physical device, for example, if the device is implemented using a chip / circuit (such as an integrated circuit or a logic circuit, etc.). The communication module can be an input and output circuit and / or a communication interface, performing input operations (corresponding to the aforementioned receiving operations) and output operations (corresponding to the aforementioned sending operations); the processing module is an integrated processor or microprocessor or circuit (such as an integrated circuit or a logic circuit, etc.).

[0517] The division of modules in this application is illustrative and represents only a logical functional division. In actual implementation, other division methods may be used. Furthermore, the functional modules in the examples of this application may be integrated into a single processor, exist physically as separate modules, or two or more modules may be integrated into a single module. The aforementioned integrated modules may be implemented in either hardware or software functional modules.

[0518] Figure 9 is a schematic diagram of another communication device provided by an embodiment of the present application. As shown in Figure 9, optionally, the communication device 2000 can be the aforementioned first node or second node or third node or terminal, or a chip or chip system or circuit for the aforementioned first node or second node or third node or terminal. Optionally, in the present application, the chip system can be composed of chips, or can include chips and other discrete devices. Among them, the first node can be an MN in a DC scenario, the second node can be a candidate SN in a DC scenario, and the third node can be a source SN in a DC scenario.

[0519] The communication device 2000 can be used to implement the functions of any device (for example, the first node, the second node, the third node, or the terminal) in the communication system described in the above examples. The communication device 2000 may include at least one processing circuit 2010. Optionally, the processing circuit 2010 is coupled to a memory, and the memory may be located within the device, or the memory may be integrated with the processor, or the memory may be located outside the device. For example, the communication device 2000 may also include at least one memory 2020. The memory 2020 stores the necessary computer programs, computer programs or instructions and / or data for implementing any of the above examples; the processing circuit 2010 may execute the computer program stored in the memory 2020 to complete the method in any of the above examples.

[0520] The communication device 2000 may also include a transceiver circuit 2030, and the communication device 2000 can exchange information with other devices through the transceiver circuit 2030. Exemplarily, the transceiver circuit 2030 can be a transceiver, circuit, bus, module, pin or other type of communication interface. When the communication device 2000 is a chip-type device or circuit, the transceiver circuit 2030 in the device 2000 can also be an input-output circuit, or an interface circuit, which can input information (or receive information) and output information (or send information). When the communication device 2000 is a network device or terminal, the transceiver circuit 2030 can be a transmitter, a receiver or a transceiver, or a communication interface, which is not limited here.

[0521] The processing circuit 2010 may be one or more processors, or all or part of the processing circuits in one or more processors. The processing circuit 2010 may be an integrated processor, microprocessor, integrated circuit, or logic circuit, and the processor may determine output information based on input information.

[0522] Coupling in this application refers to an indirect coupling or communication connection between devices, units, or modules, and can be electrical, mechanical, or other forms, used for information exchange between devices, units, or modules. Processing circuit 2010 may operate in conjunction with memory 2020 and transceiver circuit 2030. This application does not limit the specific connection medium between the processing circuit 2010, memory 2020, and transceiver circuit 2030.

[0523] Optionally, as shown in FIG9 , the processing circuit 2010, the memory 2020, and the transceiver circuit 2030 are interconnected via a bus 2040. Optionally, the bus may include an address bus, a data bus, a control bus, or other types of buses. Furthermore, for ease of illustration, FIG9 shows one bus 2040, but this does not mean that there is only one bus or only one type of bus.

[0524] It should be understood that the processors mentioned in the embodiments of the present application may be the following devices or the circuit portions of the following devices used for processing functions: a central processing unit (CPU), 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, etc. The general-purpose processor may be a microprocessor or any conventional processor.

[0525] It should also be understood that the memory mentioned in the embodiments of the present application may be a volatile memory and / or a non-volatile memory. 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). For example, RAM can be used as an external cache. By way of example and not limitation, RAM includes the following forms: static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct rambus RAM (DR RAM).

[0526] 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.

[0527] 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.

[0528] An embodiment of the present application also provides a computer-readable storage medium on which computer instructions for implementing the method executed by the first node, the second node, the third node, or the terminal in the above embodiment are stored.

[0529] An embodiment of the present application also provides a computer program product, which includes: computer program code or instructions, which, when executed by a computer, implements the method executed by the first node, the second node, the third node, or the terminal in the above embodiment.

[0530] An embodiment of the present application further provides a communication system, which includes the first node, the second node, the third node, or the terminal in the above embodiment.

[0531] The explanation of the relevant contents and beneficial effects of any of the above-mentioned devices can be referred to the corresponding method embodiments provided above and will not be described again here.

[0532] It should be understood that in the various embodiments of the present application, unless otherwise specified or there is a logical conflict, the terms and / or descriptions between different embodiments are consistent and can be referenced to each other, and the technical features in different embodiments can be combined to form new embodiments according to their internal logical relationships.

[0533] It should be understood that in some of the above embodiments, the devices in the existing network architecture are mainly used as examples for illustrative description, and the specific form of the devices is not limited in the embodiments of the present application. For example, devices that can achieve the same functions in the future are applicable to the embodiments of the present application.

[0534] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software 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 beyond the scope of this application.

[0535] 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 described again here.

[0536] 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.

[0537] 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.

[0538] 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.

[0539] 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, server, or 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 ROM, a RAM, a magnetic disk, or an optical disk.

[0540] 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, characterized in that: The method is applied to a first node in a multi-connection scenario, comprising: Sending a first message to the second node, where the first message is used to request that the second node be added as a candidate secondary node of the terminal, and the first message includes first identification information, where the first identification information is used to request advance synchronization configuration from the second node; A second message is received from the second node, where the second message is used to confirm adding the second node as a candidate secondary node of the terminal, and the second message includes a first early synchronization configuration, where the first early synchronization configuration corresponds to the first identification information.

2. The method according to claim 1, characterized in that The sending the first message to the second node includes: receiving a third message from a third node, where the third message includes an identifier of the second node and the first identifier information, and the third node is a secondary node currently serving the terminal; In response to the third message, the first message is sent to the second node.

3. The method according to claim 1 or 2, characterized in that The method further comprises: A fourth message is sent to a third node, where the fourth message includes the first advance synchronization configuration, wherein the third node is a secondary node currently serving the terminal.

4. The method according to any one of claims 1 to 3, characterized in that The method further comprises: A fifth message is received from the second node, where the fifth message includes the timing advance TA of the first cell, the identifier of the third node, and the first identifier information, where the first cell belongs to the second node, and the third node is a secondary node currently serving the terminal.

5. The method according to claim 4, characterized in that The method further comprises: In response to the fifth message, a sixth message is sent to the third node, where the sixth message includes the TA of the first cell and the first identification information.

6. The method according to claim 5, characterized in that The method further comprises: Receive a seventh message from the third node, where the seventh message is used to indicate that a switching command has been sent to the terminal, where the switching command is used to instruct the primary and secondary cells of the terminal to switch to the first cell, and the seventh message includes an identifier of the second node and identifier information of the first cell.

7. The method according to claim 6, characterized in that The method further comprises: In response to the seventh message, an eighth message is sent to the second node, where the eighth message is used to indicate that the handover command has been sent to the terminal, and the eighth message includes identification information of the first cell.

8. The method according to any one of claims 1 to 7, characterized in that The first early synchronization configuration includes a random access preamble index and / or a random access time-frequency resource.

9. The method according to any one of claims 1 to 8, characterized in that The second message further includes a second early synchronization configuration, the fourth message further includes the second early synchronization configuration, and the method further includes: receiving a ninth message from the third node, the ninth message including the encapsulated second early synchronization configuration; In response to the ninth message, a tenth message is sent to the terminal, the tenth message including the encapsulated second early synchronization configuration, the first early synchronization configuration and the encapsulated second early synchronization configuration are used for early synchronization of a first cell, and the first cell belongs to the second node.

10. The method according to claim 9, characterized in that The advance synchronization is a synchronization process performed by the terminal before receiving the handover command.

11. The method according to any one of claims 1 to 10, characterized in that The first message further includes first indication information, where the first indication information is used to request the LTM to add the second node as a candidate secondary node of the terminal.

12. The method according to any one of claims 1 to 11, characterized in that The third message further includes second indication information, where the second indication information is used to trigger the first node to request the second node to be added as a candidate secondary node of the terminal with respect to the LTM.

13. The method according to any one of claims 1 to 12, characterized in that The first message further includes identification information of K recommended cells, where the K cells include a first cell, K is an integer greater than or equal to 1, and the first cell belongs to the second node.

14. The method according to claim 13, characterized in that The third message also includes identification information of the K cells.

15. The method according to any one of claims 1 to 14, characterized in that The first message further includes second identification information, where the second identification information is used to request an advance synchronization configuration from the second node. The second message further includes a third advance synchronization configuration, where the third advance synchronization configuration corresponds to the second identification information.

16. A communication method, characterized in that: The method is applied to a second node in a multi-connection scenario, comprising: receiving a first message from a first node, where the first message is used to request that the second node be added as a candidate secondary node of the terminal, and the first message includes first identification information, where the first identification information is used to request advance synchronization configuration; A second message is sent to the first node, where the second message is used to confirm adding the second node as a candidate secondary node of the terminal, and the second message includes a first early synchronization configuration, where the first early synchronization configuration corresponds to the first identification information.

17. The method according to claim 16, characterized in that The method further comprises: A fifth message is sent to the first node, where the fifth message includes a timing advance TA of a first cell, an identifier of the third node, and first identifier information, where the first cell belongs to the second node, and the TA is determined during an advance synchronization process of the first cell.

18. The method according to claim 17, characterized in that The method further comprises: An eighth message is received from the first node, where the eighth message is used to indicate that a handover command has been sent to the terminal, where the handover command is used to instruct the primary and secondary cells of the terminal to switch to the first cell, and the eighth message includes identification information of the first cell.

19. The method according to any one of claims 16 to 18, characterized in that The first early synchronization configuration includes a random access preamble index and / or a random access time-frequency resource.

20. The method according to any one of claims 16 to 19, characterized in that The first message further includes first indication information, where the first indication information is used to request the LTM to add the second node as a candidate secondary node of the terminal.

21. The method according to any one of claims 16 to 20, characterized in that The first message further includes identification information of K recommended cells, where the K cells include a first cell, the first cell belongs to the second node, and K is an integer greater than or equal to 1.

22. A communication method, characterized in that: The method is applied to a third node in a multi-connection scenario, where the third node is a secondary node currently serving a terminal, and includes: Determine a third message, where the third message includes an identifier of the second node and the first identifier information, and the third message is used to trigger the first node to request the second node to configure an advance synchronization for the first identifier information; A third message is sent to the first node.

23. The method according to claim 22, characterized in that The method further comprises: receiving a fourth message from the first node, where the fourth message includes a first early synchronization configuration, and the first early synchronization configuration corresponds to the first identification information; Based on the first early synchronization configuration, the second cell indicates to the terminal to initiate early synchronization for the first cell, wherein the first early synchronization configuration is the configuration of the first cell, the first cell belongs to the second node, and the second cell belongs to the third node.

24. The method according to claim 23, wherein The first early synchronization configuration is associated with the second cell.

25. The method according to claim 23 or 24, characterized in that The fourth message further includes a second early synchronization configuration, and the method further includes: In response to the fourth message, a ninth message is sent to the first node, where the ninth message includes the encapsulated second early synchronization configuration, and the encapsulated second early synchronization configuration is used for early synchronization of the first cell.

26. The method according to any one of claims 23 to 25, characterized in that The method further comprises: A sixth message is received from the first node, where the sixth message includes the timing advance TA of the first cell and the first identification information.

27. The method according to claim 26, characterized in that The method further comprises: Determine, according to the sixth message, that the TA of the first cell is associated with the terminal; A handover command is sent to the terminal, where the handover command is used to instruct the primary and secondary cells of the terminal to be handed over to the first cell, and the handover command includes the TA of the first cell.

28. The method according to claim 27, characterized in that The method further comprises: A seventh message to the first node, where the seventh message is used to indicate that the handover command has been sent to the terminal, and the seventh message includes an identifier of the second node and identifier information of the first cell.

29. The method according to any one of claims 22 to 28, characterized in that The third message further includes second indication information, where the second indication information is used to trigger the first node to request the second node to be added as a candidate secondary node of the terminal with respect to the LTM.

30. The method according to any one of claims 22 to 29, characterized in that The third message further includes identification information of K recommended cells, where the K cells include a first cell, the first cell belongs to the second node, and K is an integer greater than or equal to 1.

31. A communication device, characterized in that: The method comprises a module or unit for executing the method according to any one of claims 1 to 15, or a module or unit for executing the method according to any one of claims 16 to 21, or a module or unit for executing the method according to any one of claims 22 to 30.

32. A communication device, characterized in that: The communication device includes: at least one processor, and the at least one processor is used to execute a computer program or instruction so that the method according to any one of claims 1 to 15, or the method according to any one of claims 16 to 21, or the method according to any one of claims 22 to 30 is executed.

33. The communication device according to claim 32, wherein: The communication device further comprises a memory for storing the computer program or instructions; and / or, The communication device further includes a communication interface, which is coupled to the at least one processor and is used for the communication device to exchange information with other communication devices.

34. The communication device according to claim 32 or 33, characterized in that The communication device is a chip or a chip system.

35. A communication system, characterized in that: The method comprises at least one of a first node, a second node or a third node, wherein the first node is used to execute the method according to any one of claims 1 to 15, the second node is used to execute the method according to any one of claims 16 to 21, and the third node is used to execute the method according to any one of claims 22 to 30.

36. A computer-readable storage medium, characterized in that The computer-readable storage medium stores program codes or instructions for execution by a device. When the program codes or instructions are executed, the method according to any one of claims 1 to 30 is performed.

37. A computer program product, characterized in that The invention comprises instructions which, when executed on a computer, cause the method according to any one of claims 1 to 30 to be performed.

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