Method of communication and communication device

Description

1 / 79 METHOD OF COMMUNICATION AND COMMUNICATION DEVICE TECHNICAL FIELD

[0001] This application relates to the field of communication technologies and, more specifically, to a method of communication and a communication device. BACKGROUND

[0002] In the field of communication, the movement of a terminal device triggers a cell switching in a plurality of pre-configured candidate cells; more specifically, a service cell of the terminal device is switched to any one of the plurality of candidate cells. A cell switching decision is made by a distributed unit (DU) in an access network device. Specifically, the terminal device reports a measurement report of a candidate cell to the DU; and the DU determines, based on the measurement report of the candidate cell, the candidate cell as a target cell for a switching and indicates, in a cell switching command, the switching of the terminal device's service cell to the target cell.

[0003] After completing the cell exchange, the terminal device performs data communication with a DU corresponding to the target cell. Frequent movement of the terminal device may cause the DU to rapidly trigger a plurality of subsequent cell exchanges on the plurality of candidate cells. In this case, the terminal device needs to initiate random access procedures to all candidate cells to obtain timing advances (TA) from all candidate cells.

[0004] However, in the above manner, the terminal device initiates excessive random access procedures, resulting in high power consumption and high random access interference. How to reduce the number of random access procedures initiated by the terminal device is a problem. Petition 870250104098, dated 11 / 13 / 2025, page 8 / 97 2 / 79 urgent technical issue to be resolved. SUMMARY

[0005] This application provides a method of communication and a communication device for reducing the number of random access procedures initiated by a terminal device.

[0006] According to a first aspect, a communication method is provided. The method includes: A terminal device determines information about a TA of a first candidate cell; and the terminal device reports the information about the TA of the first candidate cell to a first network device.

[0007] Specifically, the terminal device reports the TA information of the first candidate cell to the first network device, so that the first network device can obtain the TA information of the first candidate cell. Similarly, the first network device can determine, based on the TA information of the first candidate cell, whether the terminal device needs to be triggered to initiate a random access procedure for the first candidate cell. When the network device determines that the terminal device does not need to be triggered to initiate the random access procedure for the first candidate cell, the number of random access procedures that need to be initiated by the terminal device can be effectively reduced.

[0008] In a possible implementation, the method also includes: The terminal device receives indication information, where the indication information indicates to report information about a TA of a candidate cell, and the candidate cell includes the first candidate cell.

[0009] In this way, the terminal device can report information about the TA of the candidate cell based on an indication of the indication information. This helps to improve Petition 870250104098, dated 11 / 13 / 2025, page 9 / 97 3 / 79 efficiency of information exchange between the terminal device and the network device.

[0010] In one possible implementation, the information about the TA of the first candidate cell includes at least one of the following: the TA of the first candidate cell; or information indicating that the TA of the first candidate cell is valid; or the remaining validity time of the TA of the first candidate cell; or a time offset of the TA of the first candidate cell, where the time offset corresponds to the duration of the TA of the first candidate cell.

[0011] Specifically, information about the TA of the first candidate cell may be the TA value, or valid indication information, or remaining valid time, or time offset, or similar. This information helps the first network device determine whether the terminal device needs to be triggered to initiate a number of random access procedures for the first candidate cell. When the first network device determines, based on one or more items of the preceding information, not to trigger the terminal device to initiate the random access procedure for the first candidate cell, the number of random access procedures that need to be initiated by the terminal device can be effectively reduced.

[0012] In one possible implementation, the fact that the terminal device receives the indication information includes: The terminal device receives the indication information and an identifier of a target cell from a switch that are from a second network device, where the target cell is a second candidate cell, and the second candidate cell belongs to the first network device; or the terminal device receives the indication information from the first network device.

[0013] Specifically, the terminal device can receive Petition 870250104098, dated 11 / 13 / 2025, page 10 / 97 4 / 79 The indication information is transmitted in a plurality of ways. For example, the terminal device receives the indication information from the second network device, where the second network device is a service network device of the terminal device; or the terminal device receives the indication information from the first network device, where the first network device is a service network device of the terminal device.

[0014] In a possible implementation, the second candidate cell is different from the first candidate cell.

[0015] In this way, this helps to reduce the number of random access procedures that need to be initiated by the terminal device.

[0016] In a possible implementation, the indication information indicates reporting information about the TA of the first candidate cell.

[0017] In this way, the terminal device can report TA information from the first candidate cell to the network device based on the indication information, to improve the efficiency of information exchange between the terminal device and the network device.

[0018] In one possible implementation, the first candidate cell does not belong to the first network device.

[0019] According to a second aspect, a communication method is provided, including: A first network device receives information about a TA from a first candidate cell, wherein the first candidate cell does not belong to the first network device; and the first network device sends an identifier of a target cell from a switch and first indication information to a terminal device, wherein the first indication information indicates to access the target cell in a random access channel hopping manner and the target cell is the first candidate cell. Petition 870250104098, dated 11 / 13 / 2025, page 11 / 97 5 / 79

[0020] Specifically, on the premise that the first network device has obtained the TA information of the first candidate cell, the first network device sends the first indication information and the identifier of the target cell (which is the first candidate cell) from the switch to the terminal device, so that the terminal device can directly access the target cell without initiating a random access procedure for the first candidate cell. In this way, the number of random access procedures initiated by the terminal device can be reduced.

[0021] Specifically, the first network device can determine, based on information obtained about the TA of the first candidate cell, that the terminal device and / or a network device corresponding to the first candidate cell possesses / possesses the TA of the first candidate cell. After the first network device determines that the terminal device accesses the first candidate cell, uplink data transmission can be performed between the terminal device and the network device corresponding to the first candidate cell, based on information about the TA of the first candidate cell. Therefore, the first network device determines that the terminal device does not need to be triggered to initiate the random access procedure for the first candidate cell. In this way, the number of random access procedures initiated by the terminal device can be effectively reduced.

[0022] In one possible implementation, the first network device receives information about the TA of the first candidate cell, including: The first network device receives information about the TA of the first candidate cell from the terminal device; or the first network device receives information about the TA of the first candidate cell from a second network device.

[0023] In this way, the first network device can obtain Petition 870250104098, dated 11 / 13 / 2025, page 12 / 97 6 / 79 Information about the TA of the first candidate cell is transmitted in a plurality of ways. For example, the first network device receives information about the TA of the first candidate cell from the terminal device, or the first network device receives information about the TA of the first candidate cell from the second network device.

[0024] In one possible implementation, the method also includes: The first network device sends a second indication to the terminal device, where the second indication indicates reporting information about a TA of a candidate cell; or the second indication indicates reporting information about the TA of the first candidate cell.

[0025] In this way, the first network device can receive information about the TA of the first candidate cell from the terminal device.

[0026] In one possible implementation, the method also includes: The first network device sends request information to the second network device, where the request information is used to request information about the TA of the first candidate cell. [002Ί] In this way, the first network device can receive information about the TA of the first candidate cell from the second network device.

[0028] In one possible implementation, the information about the TA of the first candidate cell includes at least one of the following: the TA of the first candidate cell; or information indicating that the TA of the first candidate cell is valid; or the remaining validity time of the TA of the first candidate cell; or a time offset of the TA of the first candidate cell, where the time offset corresponds to the duration of the TA of the first candidate cell.

[0029] Specifically, the information about the TA of the first candidate cell can be the TA value, or the information of Petition 870250104098, dated 11 / 13 / 2025, page 13 / 97 7 / 79 valid indication, or remaining valid time, or time offset, or similar. The information assists the first network device in determining whether the terminal device needs to be triggered to initiate a number of random access procedures for the first candidate cell. When the first network device decides, based on one or more items of the preceding information, not to trigger the terminal device to initiate the random access procedure for the first candidate cell, the number of random access procedures that need to be initiated by the terminal device can be effectively reduced.

[0030] According to a third aspect, a method of communication is provided, including: A first network device sends a first indication information to a terminal device, where the first indication information indicates that the terminal device should obtain information about a TA of a first candidate cell; and the first network device sends an identifier of a target cell from a switch and second indication information to the terminal device, where the target cell is a second candidate cell, the second candidate cell belongs to a second network device, the second indication information indicates that it should report the TA information of the first candidate cell to the second network device, and the first candidate cell does not belong to the second network device.

[0031] Specifically, the first network device can indicate to the terminal device to obtain information about the The TA (Technical Access) of the first candidate cell is then sent to the terminal device to report the TA information of the first candidate cell to the second network device. Similarly, the second network device can determine, based on the information obtained about the TA of the first candidate cell, whether to trigger the terminal device to initiate an access procedure. Petition 870250104098, dated 11 / 13 / 2025, page 14 / 97 8 / 79 random for the first candidate cell. When the second network device determines that the terminal device does not need to be triggered to initiate the random access procedure for the first candidate cell, the number of random access procedures that need to be initiated by the terminal device can be effectively reduced.

[0032] In one possible implementation, the information about the TA of the first candidate cell includes at least one of the following: the TA of the first candidate cell; or information indicating that the TA of the first candidate cell is valid; or the remaining validity time of the TA of the first candidate cell; or a time offset of the TA of the first candidate cell, where the time offset corresponds to the duration of the TA of the first candidate cell.

[0033] Specifically, the TA information of the first candidate cell may be the TA value, or valid indication information, or remaining valid time, or time offset, or similar. This information helps the second network device determine whether the terminal device needs to be triggered to initiate a number of random access procedures for the first candidate cell. When the second network device determines, based on one or more items of the previous information, not to trigger the terminal device to initiate the random access procedure for the first candidate cell, the number of random access procedures that need to be initiated by the terminal device can be effectively reduced.

[0034] In a possible implementation, the second candidate cell is different from the first candidate cell.

[0035] In this way, this helps to reduce the number of random access procedures that need to be initiated by the terminal device.

[0036] According to a fourth aspect, a method of Petition 870250104098, dated 11 / 13 / 2025, page 15 / 97 9 / 79 communication is provided, including: A first network device obtains information about a timing advance TA of a first candidate cell, where the first candidate cell belongs to the first network device or a third network device, and the information about the TA of the first candidate cell is used to determine the use of a random access channel hopping mode; and the first network device sends the information about the TA of the first candidate cell to a second network device using a fourth network device.

[0037] Specifically, the first network device can send information about the TA of the first candidate cell, which the first network device possesses, to the second network device, using the fourth network device. This helps the second network device determine, based on the information about the TA of the first candidate cell, whether a terminal device needs to be triggered to initiate a random access procedure for the first candidate cell. When the second network device determines that the terminal device does not need to be triggered to initiate the random access procedure for the first candidate cell, the number of random access procedures that need to be initiated by the terminal device can be effectively reduced.

[0038] In one possible implementation, the first network device obtains TA information from the first candidate cell, including: The first network device receives TA information from the first candidate cell from the fourth network device; or the first network device receives a contention-free random access preamble sent by the terminal device in the first candidate cell; and the first network device determines TA information from the first candidate cell based on the contention-free random access preamble. Petition 870250104098, dated 11 / 13 / 2025, page 16 / 97 10 / 79

[0039] In one possible implementation, the method also includes: The first network device receives request information from the fourth network device, where the request information is used to request information about the TA of the first candidate cell.

[0040] In one possible implementation, the information about the TA of the first candidate cell includes at least one of the following: the TA of the first candidate cell; or information indicating that the TA of the first candidate cell is valid; or the remaining validity time of the TA of the first candidate cell; or a time offset of the TA of the first candidate cell, where the time offset corresponds to the duration of the TA of the first candidate cell.

[0041] According to a fifth aspect, a communication method is provided, including: A first network device receives a contention-free random access preamble from a first candidate cell, where the contention-free random access preamble is used to determine information about a TA of the first candidate cell; and the first network device sends the information about the TA of the first candidate cell to a third network device using a second network device.

[0042] In a possible implementation, the method also includes: The first network device receives request information from the second network device, where the request information is used to request obtaining information about the TA of the first candidate cell.

[0043] In a possible implementation, the information about the TA of the first candidate cell includes at least one of the following: a TA of the first candidate cell; or indicative information indicating that the TA of the first candidate cell is valid; or the remaining validity time of the TA of the first candidate cell; or a time offset of the TA of the first cell. Petition 870250104098, dated 11 / 13 / 2025, page 17 / 97 11 / 79 candidate, where the time offset corresponds to the TA duration of the first candidate cell.

[0044] According to a sixth aspect, a communication apparatus is provided, including: a processing unit, configured to determine information about a TA of a first candidate cell; and a transceiver unit, configured to report the information about the TA of the first candidate cell to a first network device.

[0045] In one possible implementation, the transceiver unit is further configured to receive indication information, where indication information indicates reporting information about a TA of a candidate cell, and the candidate cell includes the first candidate cell.

[0046] In one possible implementation, the information about the TA of the first candidate cell includes at least one of the following: the TA of the first candidate cell; or information indicating that the TA of the first candidate cell is valid; or the remaining validity time of the TA of the first candidate cell; or a time offset of the TA of the first candidate cell, where the time offset corresponds to the duration of the TA of the first candidate cell.

[0047] In one possible implementation, the transceiver unit is further configured to receive the indication information and an identifier of a target cell from a switch that are from a second network device, where the target cell is a second candidate cell, and the second candidate cell belongs to the first network device; or the transceiver unit is further configured to receive the indication information from the first network device.

[0048] In a possible implementation, the second candidate cell is different from the first candidate cell.

[0049] In a possible implementation, the indication information indicates reporting information about the TA of the first Petition 870250104098, dated 11 / 13 / 2025, page 18 / 97 12 / 79 candidate cell.

[0050] In a possible implementation, the first candidate cell does not belong to the communication device.

[0051] According to a seventh aspect, a communication apparatus is provided, including: a transceiver unit configured to receive information about a TA from a first candidate cell, wherein the first candidate cell does not belong to the communication apparatus. The transceiver unit is further configured to send an identifier of a target cell from a switch and a first indication information to a terminal device, wherein the first indication information indicates access to the target cell by means of random access channel hopping, and the target cell is the first candidate cell.

[0052] In one possible implementation, the transceiver unit is further configured to receive TA information from the first candidate cell from the terminal device; or the transceiver unit is further configured to receive TA information from the first candidate cell from a second network device.

[0053] In one possible implementation, the transceiver unit is further configured to send a second indication information to the terminal device, where the second indication information indicates reporting information about a TA of a candidate cell; or the second indication information indicates reporting information about the TA of the first candidate cell.

[0054] In one possible implementation, the transceiver unit is further configured to send request information to the second network device, where the request information is used to request TA information from the first candidate cell.

[0055] In one possible implementation, the TA information for the first candidate cell includes at least one of the following: the TA of the first candidate cell; or information of Petition 870250104098, dated 11 / 13 / 2025, page 19 / 97 13 / 79 indicates that the TA of the first candidate cell is valid; or the remaining validity time of the TA of the first candidate cell; or a time offset of the TA of the first candidate cell, where the time offset corresponds to the duration of the TA of the first candidate cell.

[0056] According to an eighth aspect, a communication apparatus is provided, including a transceiver unit, configured to send a first indication information to a terminal device, where the first indication information indicates that the terminal device should obtain information about a TA from a first candidate cell. The transceiver unit is further configured to send an identifier of a target cell from a switch and a second indication information to the terminal device, where the target cell is a second candidate cell, the second candidate cell belongs to a second network device, the second indication information indicates that it should report the TA information of the first candidate cell to the second network device, and the first candidate cell does not belong to the second network device.

[0057] In one possible implementation, the information about the TA of the first candidate cell includes at least one of the following: the TA of the first candidate cell; or information indicating that the TA of the first candidate cell is valid; or the remaining validity time of the TA of the first candidate cell; or a time offset of the TA of the first candidate cell, where the time offset corresponds to the duration of the TA of the first candidate cell.

[0058] In a possible implementation, the second candidate cell is different from the first candidate cell.

[0059] According to a ninth aspect, a communication apparatus is provided, including: a processing unit, configured to obtain information about a timing advance TA of a first candidate cell, where the first Petition 870250104098, dated 11 / 13 / 2025, page 20 / 97 14 / 79 candidate cell belongs to a first network device or a third network device, and the TA information of the first candidate cell is used to determine the use of a random access channel hopping mode; and a transceiver unit, configured to send the TA information of the first candidate cell to a second network device using a fourth network device.

[0060] In one possible implementation, the transceiver unit is further configured to receive TA information from the first candidate cell of the fourth network device; or the transceiver unit is further configured to receive a contention-free random access preamble sent by a terminal device in the first candidate cell; and the processing unit is further configured to determine TA information from the first candidate cell based on the contention-free random access preamble.

[0061] In one possible implementation, the method also includes: The first network device receives request information from the fourth network device, where the request information is used to request information about the TA of the first candidate cell.

[0062] In one possible implementation, the information about the TA of the first candidate cell includes at least one of the following: the TA of the first candidate cell; or information indicating that the TA of the first candidate cell is valid; or the remaining validity time of the TA of the first candidate cell; or a time offset of the TA of the first candidate cell, where the time offset corresponds to the duration of the TA of the first candidate cell.

[0063] According to a tenth aspect, a communication apparatus is provided, including: a transceiver unit configured to receive a contention-free random access preamble from a first candidate cell, where the preamble Petition 870250104098, dated 11 / 13 / 2025, page 21 / 97 15 / 79 contention-free random access is used to determine information about a TA of the first candidate cell. The transceiver unit is configured to send the information about the TA of the first candidate cell to a third network device using a second network device.

[0064] In one possible implementation, the transceiver unit is further configured to receive request information from the second network device, where the request information is used to request obtaining information about the TA of the first candidate cell.

[0065] In a possible implementation, the information about the TA of the first candidate cell includes at least one of the following: a TA of the first candidate cell; or indication information indicating that the TA of the first candidate cell is valid; or remaining validity time of the TA of the first candidate cell; or a time offset of the TA of the first candidate cell, where the time offset corresponds to the duration of the TA of the first candidate cell.

[0066] According to an eleventh aspect, a communication apparatus, including a processor, is provided. The processor is configured to enable, through the execution of a computer program or instructions or the use of a logic circuit, the communication apparatus to perform the method according to any one of the first aspect and the possible implementations of the first aspect, the communication apparatus to perform the method according to any one of the second aspect and the possible implementations of the second aspect, the communication apparatus to perform the method according to any one of the third aspect and the possible implementations of the third aspect, the communication apparatus to perform the method according to any one of the fourth aspect and the possible implementations of the fourth aspect, or the communication apparatus to perform the method according to Petition 870250104098, dated 11 / 13 / 2025, p. 22 / 97 16 / 79 any of the fifth aspect and the possible implementations of the fifth aspect.

[0067] In one possible implementation, the communication device also includes a memory, configured to store the computer program or instructions.

[0068] In one possible implementation, the communication device also includes a communication interface, configured for input and / or output of a signal.

[0069] According to a twelfth aspect, a communication apparatus is provided, including a logic circuit and an input / output interface. The input / output interface is configured to input and / or output a signal. The logic circuit is configured to perform the method according to any one of the first aspect and the possible implementations of the first aspect. Alternatively, the logic circuit is configured to perform the method according to any one of the second aspect and the possible implementations of the second aspect. Alternatively, the logic circuit is configured to perform the method according to any one of the third aspect and the possible implementations of the third aspect. Alternatively, the logic circuit is configured to perform the method according to any one of the fourth aspect and the possible implementations of the fourth aspect.Alternatively, the logic circuit is configured to perform the method according to any one of the fifth aspect and the possible implementations of the fifth aspect.

[0070] According to a thirteenth aspect, a computer-readable storage medium is provided. The computer-readable storage medium stores a computer program or instructions. When the computer program or instructions run on a computer, the method according to any one of the first aspect and the possible implementations of the first aspect is performed, or the method of Petition 870250104098, dated 11 / 13 / 2025, page 23 / 97 17 / 79 according to any one of the second aspect and the possible implementations of the second aspect is carried out, or the method according to any one of the third aspect and the possible implementations of the third aspect is carried out, or the method according to any one of the fourth aspect and the possible implementations of the fourth aspect is carried out, or the method according to any one of the fifth aspect and the possible implementations of the fifth aspect is carried out.

[0071] According to the fourteenth aspect, a computer program product is provided, including instructions. When the instructions run on a computer, the method according to any of the aspects of the first and the possible implementations of the first aspect is realized, or the method according to any of the aspects of the second and the possible implementations of the second aspect is realized, or the method according to any of the aspects of the third and the possible implementations of the third aspect is realized, or the method according to any of the aspects of the fourth and the possible implementations of the fourth aspect is realized, or the method according to any of the aspects of the fifth and the possible implementations of the fifth aspect is realized.

[0072] According to a fifteenth aspect, a chip is provided that includes a logic circuit. The logic circuit is configured to perform the method according to any one of the first aspect and the possible implementations of the first aspect. Alternatively, the logic circuit is configured to perform the method according to any one of the second aspect and the possible implementations of the second aspect. Alternatively, the logic circuit is configured to perform the method according to any one of the third aspect and the possible implementations of the third aspect. Alternatively, the logic circuit is configured to perform the method according to any one of the fourth aspect and the Petition 870250104098, dated 11 / 13 / 2025, p. 24 / 97 18 / 79 possible implementations of the fourth aspect. Alternatively, the logic circuit is configured to perform the method according to any one of the fifth aspect and the possible implementations of the fifth aspect.

[0073] For descriptions of the beneficial effects of the fourth to fifteenth aspects, see the descriptions of the beneficial effects of the first to third aspects. Details are not described again in this document. BRIEF DESCRIPTION OF DRAWINGS

[0074] FIG. 1 is a diagram of a communication system 100 to which one embodiment of this application is applicable.

[0075] FIG. 2 is a diagram of an application scenario 200 according to one embodiment of this application.

[0076] FIG. 3 is a diagram of a cell switching procedure.

[0077] FIG. 4 is a schematic interaction flowchart of a 400 communication method according to one modality of this request.

[0078] FIG. 5 is a schematic interaction flowchart of a 500 communication method according to a modality of this request.

[0079] FIG. 6A and FIG. 6B are a schematic interaction flowchart of a communication method 600 according to a modality of this request.

[0080] FIG. 7A and FIG. 7B are a schematic interaction flowchart of a communication method 700 according to a modality of this request.

[0081] FIG. 8A and FIG. 8B are a schematic interaction flowchart of an 800 communication method according to a modality of this request.

[0082] FIG. 9 is a diagram of a communication device structure 900 according to an embodiment of this application.

[0083] FIG. 10 is a diagram of a device structure. Petition 870250104098, dated 11 / 13 / 2025, p. 25 / 97 19 / 79 communication 1000 in accordance with a modality of this request.

[0084] FIG. 11 is a diagram of a communication device structure 1100 according to an embodiment of this application.

[0085] FIG. 12 is a diagram of a structure of a 1200 communication device according to an embodiment of this application; and

[0086] FIG. 13 is a diagram of a communication device structure 1300 according to an embodiment of this application. DESCRIPTION OF THE MODALITIES

[0087] We describe the technical solutions for this application below with reference to the attached drawings.

[0088] The technical solutions in embodiments of this application can be applied to various communication systems, for example, a long-term evolution (LTE) system, a frequency division duplex (FDD) LTE system, a time division duplex (TDD) LTE system, a universal mobile telecommunications system (UMTS), a 5th generation (5G) or new radio (NR) system, a system evolved after 5G, such as a 6th generation (6G) system, and non-terrestrial network (NTN) systems, such as an intersatellite communication system and a satellite communication system. The satellite communication system includes a satellite base station and a terminal device. The satellite base station provides a communication service to the terminal device.A satellite base station can also communicate with a ground base station. A satellite can serve as a base station or as a terminal device. The satellite can be a non-terrestrial base station, a non-terrestrial device, or similar, for example, an unmanned aerial vehicle, a hot air balloon, a low Earth orbit satellite, a medium Earth orbit satellite, or an Earth orbit satellite. Petition 870250104098, dated 11 / 13 / 2025, p. 26 / 97 20 / 79 high.

[0089] The technical solutions in embodiments of this application are applicable to both homogeneous and heterogeneous network scenarios. Furthermore, a transmission point is not limited. Coordinated multipoint transmission can be performed between macro base stations, between micro base stations, and between a macro base station and a micro base station. The technical solutions are applicable to FDD / TDD systems. The technical solutions in embodiments of this application are applicable not only to low-frequency (sub-6G) scenarios, but also to high-frequency (above 6 GHz), terahertz, optical communication, and similar scenarios. The technical solutions in embodiments of this application are applicable not only to communication between a network device and a terminal, but also to communication between network devices, communication between terminals, and communication in the vehicular internet, communication in the internet of things, communication in the industrial internet, and similar scenarios.

[0090] Technical solutions in embodiments of this application may also be applied to a scenario in which a terminal is connected to a single base station. The base station connected to the terminal and a core network (CN) connected to the base station have the same pattern. For example, if the CN is a 5G core, the base station will correspondingly be a 5G base station, and the 5G base station will be directly connected to the 5G core. Alternatively, if the CN is a 6G core, the base station will be a 6G base station, and the 6G base station will be directly connected to the 6G core. The technical solutions in embodiments of this application are also applicable to a dual connectivity (DC) scenario in which a terminal is connected to at least two base stations.

[0091] The technical solutions in the modalities of this application may also use a macro-micro scenario, including different forms of base stations in a communication network. For example, Petition 870250104098, dated 11 / 13 / 2025, p. 27 / 97 21 / 79 The base station may be a satellite, a hot air balloon station, or an unmanned aerial vehicle station. The technical solutions in embodiments of this application are also applicable to a scenario in which there are both a wide-coverage base station and a narrow-coverage base station.

[0092] The technical solutions in the forms of this application can be applied to a scenario where there is a requirement for high reliability service, for example, a port, industrial manufacturing, transport and a coal mine.

[0093] It can be further understood that the technical solutions in embodiments of this application can be applied to a 5.5G wireless communication system, a 6G wireless communication system and a wireless communication system subsequent to 5.5G and 6G. Application scenarios include, among others, a terrestrial cellular communication scenario, an NTN scenario, a satellite communication scenario, a high altitude platform station (HAPS) communication scenario, a vehicle-to-everything (V2X) scenario, an integrated access and backhaul (IAB) scenario, a reconfigurable intelligent surface (RIS) communication scenario and the like.

[0094] The terminal in embodiments of this application may be a device with a wireless transceiver function and may specifically be user equipment (UE), an access terminal, a subscriber unit, a subscriber station, a mobile station, a remote station, a remote terminal, a mobile device, a user terminal, a wireless communication device, a user agent, or a user appliance. The terminal device may alternatively be a satellite phone, a mobile phone, a smartphone, a wireless data card, a wireless modem, or a communication device. Petition 870250104098, dated 11 / 13 / 2025, page 28 / 97 22 / 79 type machine, or it may be a cordless phone, a phone with session initiation protocol (SIP), a wireless local loop (WLL) station, a personal digital assistant (PDA), customer-premises equipment (CPE), a smart point-of-sale (POS) machine, a portable device with wireless communication function, a computing device or other processing device connected to a wireless modem, a vehicle-mounted device, a communication device carried on a high-altitude aircraft, a wearable device, an unmanned aerial vehicle, a robot, a device-to-device (D2D) communication terminal, a V2X terminal, a virtual reality (VR) terminal device, an augmented reality (AR) terminal device,A wireless terminal in industrial control, a wireless terminal in self-driving, a wireless terminal in telemedicine, a wireless terminal in a smart grid, a wireless terminal in transport safety, a wireless terminal in a smart city, a wireless terminal in a smart home, a terminal device in a communication network evolved after 5G or similar. This is not limited to the embodiments of this application.

[0095] In embodiments of this application, a communication device configured to implement a function of the terminal device may be a terminal device or a device that can support the terminal device in implementing the function, for example, a chip system. The device may be installed in the terminal device or used in combination with the terminal device. In embodiments of this application, the chip system may include a chip, or it may include Petition 870250104098, dated 11 / 13 / 2025, page 29 / 97 23 / 79 one chip and another discrete component.

[0096] The network device in some embodiments of this application is a device with wireless transceiver function and is configured to communicate with the terminal device. An access network device may be a node in a radio access network (RAN) and may also be called a base station, or it may be called a RAN node. The access network device may be an evolved NodeB (eNB or eNodeB) in LTE, a base station in a 5G network, for example, a gNodeB (gNB), a base station in an evolved public land mobile network (PLMN) after 5G, a broadband network gateway (BNG), an aggregation switch, an access device for a 3rd generation partnership project (3GPP) or similar.For example, the RAN can be configured as a RAN defined in a 3GPP protocol, an open radio access network (O-RAN), or a cloud radio access network (C-RAN).

[0097] The network device in embodiments of this application may further include various types of base stations, for example, a macro base station, a micro base station (also called a small cell), a relay station, a transmitting and receiving point (TRP), a transmitting point (TP), a mobile switching center, a device that performs a base station function in device-to-device (D2D), vehicle-to-everything (V2X) and machine-to-machine (M2M) communication, a network device in an NTN communication system, and the like. This is not specifically limited in embodiments of this application.

[0098] The network device in embodiments of this application may alternatively include a network element or a module that Petition 870250104098, dated 11 / 13 / 2025, p. 30 / 97 24 / 79 implements several base station functions, for example, including one or more of the following: a central unit (CU), a distributed unit (DU), or a radio unit (RU). Optionally, the CU can be further separated into a control plane (CP) of CU and a user plane (UP) of CU. CU and DU functions can be implemented by different network elements or can be implemented by a baseband unit (BBU) of the base station. An RU function can be implemented by a radio frequency device of the base station. For example, the base station radio frequency device can be a remote radio unit (RRU), a pico remote radio unit (pRRU), an active antenna unit (AAU), or another unit, module, or device with a radio frequency processing function.A communication interface protocol between the BBU and the radio frequency device can be a Common Public Radio Interface (CPRI) protocol, an Enhanced Common Public Radio Interface (eCPRI) protocol, a fronthaul interface protocol between a DU and a RU in an O-RAN system, or similar. This is not limited to.

[0099] In embodiments of this application, an apparatus configured to implement a function of the network device may be a network device; or it may be an apparatus that can support the network device in implementing the function, for example, a chip system. The apparatus may be installed in the network device or used in combination with the network device. In embodiments of this application, the chip system may include a chip, or it may include a chip and another discrete component.

[00100] FIG. 1 is a diagram of a communication system 100 to which an embodiment of this application applies; as shown in FIG. 1, the communication system 100 includes a Petition 870250104098, dated 11 / 13 / 2025, page 31 / 97 25 / 79 network device 110 and a terminal device 120. The number of terminal devices 120 and the number of network devices 110 in the communication system 100 are not limited in this application. It should be understood that FIG. 1 is merely an example for understanding and cannot limit the scope of protection claimed in this application.

[00101] It can be understood that terminal device 120 can be any of the terminal devices listed above, and network device 110 can be any of the network devices listed above. This is not limited.

[00102] Specifically, network device 110 may use a central unit (CU) DU architecture, or it may not use a CU-DU architecture. This is not limited. For ease of description, this application is described using an example where network device 110 uses a CU-DU architecture. Network device 110 includes a CU and at least one DU, and at least one DU communicates with each other using the CU.

[00103] In communication system 100, the DU of network device 110 can perform a cell switching decision. For details, see FIG. 3.

[00104] FIG. 2 is a diagram of an application scenario 200 according to an embodiment of this application; as shown in FIG. 2, application scenario 200 includes a cell no. 1 to a cell no. 3. A terminal device 120 is located in cell no. 1, and cell no. 1 is a service cell of terminal device 120. The terminal device receives an RRC reconfiguration message from cell no. 1, where the RRC reconfiguration message includes LTM candidate cell configurations from cell no. 2 and cell no. 3. Cell no. 2 and cell no. 3 are candidate cells, and candidate cells are potential target cells of a switch. The terminal device performs the first and second subsequent switching based on the same RRC reconfiguration message. Petition 870250104098, dated 11 / 13 / 2025, page 32 / 97 26 / 79

[00105] In simple terms, before the first switch, cell #1 is the service cell (i.e., an originating service cell), and cells #2 and #3 are candidate cells. After the first L1 / L2 triggered mobility (LTM) switch, the service cell of terminal device 120 is switched from cell #1 to cell #2. Cell #2 becomes a service cell of terminal device 120 after the first switch and is also a service cell before the second switch. Cell #1 becomes a candidate cell for the second switch, and cell #3 remains a candidate cell. After the second LTM switch, terminal device 120 is switched from cell #2 to cell #3. Cell #3 becomes a service cell of terminal device 120 after the second LTM switch.Cell #2 becomes a candidate cell for a third LTM switching, and cell #1 remains a candidate cell. In other words, each of cells #1 to #3 can become a service cell after a switching is completed. For ease of differentiation and description, in this application, cell #1 is defined as the originating service cell (further explanation is provided below), cell #2 is defined as a candidate cell that serves as the target cell for the first switching (terminal device 120 is switched from cell #1 to cell #2), and cell #3 is a candidate cell that does not serve as the target cell for the first switching.

[00106] In application scenario 200, a network device 110 can be a base station. If the network device 110 uses a split CU-DU architecture, the network device 110 will include one CU and at least one DU. Cell #1 to cell #3 belong to different DUs under the same CU, and all DUs can belong to network device 110. In this way, application scenario 200 can be applied to interaction within the station. Petition 870250104098, dated 11 / 13 / 2025, page 33 / 97 27 / 79 base. In application scenario 200, cells #1 to #3 can belong to different DUs under different CUs. For example, cell #1 belongs to DU 1 under CU 1, and cells #2 and #3 belong to DU 2 under CU 2, where CU 1 and CU 2 are different. Therefore, application scenario 200 can be applied to the interaction between base stations.

[00107] In conclusion, application scenario 200 can be applied to interaction between base stations and interaction within a base station. For ease of description, it is defined in embodiments of this application that a cell corresponds to a device (referred to as a network device below), and the device is a DU. For ease of differentiation, a network device 100 and a network device 400 are defined in embodiments of this application. Network device 100 (corresponding to cell #1), network device 300 (corresponding to cell #2), and network device 400 (corresponding to cell #3) can be DUs, and network device 200 is a CU. This is described in more detail below.

[00108] It should be noted that the technical solutions disclosed in this application can be applied to interaction between base stations (e.g., inter-gNB) or to interaction within a base station (e.g., intra-gNB). For ease of description, interaction within a base station is primarily used as an example for description in this application. However, related descriptions can be applied to a scenario of interaction between base stations. For example, network device 100 and network device 200 belong to base station 1, and network device 300 belongs to base station 2. Unified descriptions are provided here. The details will not be described again herein.

[00109] FIG. 3 is a diagram of a cell switching procedure; The procedure shown in FIG. 3 can be applied to a scenario where a DU 1 and a DU 2 belong to the same CU. Petition 870250104098, dated 11 / 13 / 2025, page 34 / 97 28 / 79 Furthermore, the procedure shown in FIG. 3 can also be applied to a scenario where DU 1 and DU 2 belong to different CUs, respectively, and the procedures for the two scenarios are similar. To facilitate the description, in this embodiment of this application, an example where the cell switching procedure is applied to the scenario where DU 1 and DU 2 belong to the same CU is used for description. As shown in FIG. 3, the cell switching procedure includes the following steps.

[00110] S310: A terminal device 120 sends measurement report information to DU 1.

[00111] Correspondingly, DU 1 receives the measurement report information. The measurement report information includes measurement results from a plurality of neighboring cells.

[00112] Optionally, the measurement report information is an L3 measurement result. The L3 measurement result includes the measurement results of the plurality of neighboring cells in which the terminal device 120 performs L3 smoothing processing.

[00113] S320: DU 1 sends an uplink radio resource control message transfer (UL RRC MESSAGE TRANSFER) message to CU.

[00114] Correspondingly, the CU receives the UL RRC message transfer message. The UL RRC message transfer message includes the measurement report information in S310.

[00115] S330: The CU determines to initiate an LTM configuration procedure.

[00116] Specifically, the CU determines, based on measurement report information, that LTM setup procedures need to be initiated for some or all neighboring cells in S310. In other words, the CU determines Petition 870250104098, dated 11 / 13 / 2025, page 35 / 97 29 / 79 candidate LTM cells (which may include cell no. 1 through cell no. 3 in FIG. 2) based on measurement report information, so that terminal device 120 performs an LTM switching on the candidate LTM cells.

[00117] S340: CU sends a UE CONTEXT SETUP REQUEST MESSAGE to DU 2.

[00118] Specifically, the UE context configuration request message includes an identifier for at least one candidate cell. The at least one candidate cell includes candidate cell 1 described below. For example, the at least one candidate cell includes cell #1 through cell #3 in FIG. 2. Candidate cell 1 could be cell #2 or cell #3.

[00119] Optionally, at least one candidate cell belongs to the plurality of neighboring cells. The UE context configuration request message is used to request that DU 2 provide LTM configuration information for at least one candidate cell, so that terminal device 120 can perform LTM switching based on the LTM configuration information.

[00120] S350: DU 2 sends a UE CONTEXT SETUP RESPONSE MESSAGE to CU.

[00121] Specifically, if DU 2 accepts an LTM configuration request, DU 2 determines whether to respond to the UE context configuration request message. The UE context configuration response message includes lower-layer configuration information (e.g., radio link control (RLC) configuration information, medium access control (MAC) configuration information, and physical layer (PHY) configuration information) from at least one candidate cell. This information can be used Petition 870250104098, dated 11 / 13 / 2025, page 36 / 97 30 / 79 via terminal device 120 to perform LTM switching and data transmission after LTM switching is complete.

[00122] S360: CU sends a downlink (DL) RRC message transfer message to DU 1.

[00123] Correspondingly, DU 1 receives the DL RRC message transfer message. The DL RRC message transfer message includes an RRC reconfiguration message (RRCReconfiguration), and the RRCReconfiguration message includes the lower layer configuration information of at least one candidate cell.

[00124] S370: DU 1 sends the RRCReconfiguration message to terminal device 120.

[00125] Correspondingly, terminal device 120 receives the RRCReconfiguration message.

[00126] It can be understood that a cell that receives the message RRCReconfiguration is a source service cell, that is, cell number 1.

[00127] Specifically, the RRCReconfiguration message includes the LTM configuration information provided by DU 2 for at least one candidate cell. In other words, terminal device 120 can perform LTM switching based on the RRCReconfiguration message.

[00128] Optionally, the RRCReconfiguration message may also include common random access configuration information for each of at least one candidate cell. The common random access configuration information is used by terminal device 120 to send a contention-free random access preamble to the corresponding candidate cell, and the contention-free random access preamble is used to determine a TA of the candidate cell.

[00129] Note that the RRCReconfiguration message can be used for an initial LTM switch (a first Petition 870250104098, dated 11 / 13 / 2025, page 37 / 97 31 / 79 LTM switching) and also for a plurality of subsequent switches (e.g., a second LTM switching), without requiring any additional RRCReconfiguration message. Unified descriptions are provided here. Details will not be described again below. S380: Terminal device 120 sends a message RRCReconfigurationComplete for DU 1.

[00130] Correspondingly, DU 1 receives the message RRCReconfigurationComplete.

[00131] S390: DU 1 sends the message RRCReconfigurationComplete for the CU.

[00132] Correspondingly, the CU receives the message RRCReconfigurationComplete.

[00133] S3100: Terminal device 120 sends a measurement result from candidate cell 1 to DU 1.

[00134] Correspondingly, DU 1 receives the measurement result from candidate cell 1.

[00135] Before or after S3100, DU 1 can send a plurality of physical downlink control channel (PDCCH) orders to terminal device 120. The plurality of PDCCH orders is used to instruct or trigger terminal device 120 to send contention-free random access preambles to all candidate cells in order to obtain TAs from the candidate cells. The PDCCH order includes contention-free random access configuration information from the candidate cell, and the contention-free random access configuration information is used to transmit the contention-free random access preamble. Terminal device 120 sends the contention-free random access preambles to at least one candidate cell in order to obtain a TA from the candidate cell.

[00136] It can be understood that a PDCCH order corresponds to the containment-free random access of a candidate cell. Petition 870250104098, dated 11 / 13 / 2025, p. 38 / 97 32 / 79 DU 1 sends the plurality of PDCCH orders to terminal device 120, to trigger terminal device 120 and initiate random access procedures for the plurality of candidate cells.

[00137] Optionally, terminal device 120 also receives a random access response message (random access response, RAR) from DU 1 or DU 2, where the RAR message includes the TA of the candidate cell.

[00138] S3110: DU 1 determines candidate cell 1 as a target cell for a switch.

[00139] Specifically, DU 1 determines, based on the measurement report of candidate cell 1, that the channel quality of candidate cell 1 is better than the channel quality of a service cell and further determines that the service cell of terminal device 120 is switched to candidate cell 1.

[00140] S3120: DU 1 sends an LTM command message to terminal device 120.

[00141] Correspondingly, terminal device 120 receives the LTM command. The LTM command message includes a target cell identifier. Terminal device 120 is switched to the target cell based on the LTM command. The target cell is candidate cell 1 (e.g., cell #2).

[00142] S3130: DU 1 sends an LTM notification to CU.

[00143] Specifically, the CU determines the target cell of the LTM switch based on the LTM notification. The LTM notification includes the target cell identifier, for example, a candidate cell identifier 1.

[00144] In addition, the CU can send downlink data to the DU 2 corresponding to the target cell.

[00145] S3140: DU 2 sends an access success message (ACCESS SUCCESS) to CU. Petition 870250104098, dated 11 / 13 / 2025, p. 39 / 97 33 / 79

[00146] Correspondingly, the UC receives the access success message from DU 2, where the access success message includes the target cell identifier and indicates to the CU that terminal device 120 has successfully accessed the target cell.

[00147] Specifically, terminal device 120 can access the target cell in a random manner, for example, through a random access channel, or it can access the target cell in a channelless or non-channel random access manner, for example, by directly accessing the target cell through a shared physical uplink (PUSCH) channel or a physical uplink control channel (PUCCH), without the need to send a random access preamble. The PUSCH or PUCCH needs to carry indication information, and the indication information indicates, to DU 2, that terminal device 120 has successfully accessed candidate cell 1.

[00148] It can be understood that, after DU 2 determines that terminal device 120 successfully accesses the target cell, DU 2 sends the access success message, including the target cell identifier, to the CU. Furthermore, the CU can determine, based on the target cell identifier contained in the access success message, that terminal device 120 was successfully switched to the target cell.

[00149] After completing the cell exchange, terminal device 120 performs data communication with the DU corresponding to the target cell. For ease of description, this request is described using an example where the target cell is cell #2. Cell #1 corresponds to a source DU, cell #2 corresponds to a target DU, and cell #3 corresponds to another candidate DU. Frequent movement of terminal device 120 can quickly trigger a plurality of subsequent cell exchanges in the plurality of candidate cells. For example, the service cell of terminal device 120 is switched from cell #2 to cell #3. As the target DU does not have information Petition 870250104098, dated 11 / 13 / 2025, page 40 / 97 34 / 79 regarding a TA of cell #3 (which is the information about the TA of cell #3 of terminal device 120), or the target DU does not know if terminal device 120 possesses the information about the TA of cell #3, the target DU instructs terminal device 120 to initiate a random access procedure for cell #3 in order to obtain the TA of cell #3. As a result, terminal device 120 needs to keep initiating the random access procedure for cell #3, resulting in high power consumption and high random access interference from terminal device 120.

[00150] In view of this, this application provides a method of communication and a communication device to reduce the number of random access procedures initiated by a terminal device.

[00151] The communication method and communication apparatus in embodiments of this application are described below with reference to the attached drawings.

[00152] It should be noted that a method 400 and a method 500 are described, respectively, from two dimensions: a candidate DU and the terminal device. However, method 400 and method 500 are related at a technical solution level or are described, respectively, from different device perspectives based on the same technical problem.

[00153] FIG. 4 is a schematic interaction flowchart of a 400 communication method according to one embodiment of this application. The 400 method can be implemented by a network device 100, a network device 200 and a terminal device 120, or it can be implemented by modules and / or components (e.g., chips or integrated circuits) installed in the network device 100, the network device 200 and the terminal device 120 and having corresponding functions. This is not limited. An example is presented below in which the 400 method is implemented by the network device 100, by the Petition 870250104098, dated 11 / 13 / 2025, page 41 / 97 35 / 79 network device 200 and terminal device 120 for description purposes.

[00154] For network device 100 and network device 200, see descriptions in FIG. 2. Details are not described again. Method 400 includes the following steps.

[00155] S410: Network device 100 receives information about a TA from a candidate cell 1.

[00156] Specifically, network device 100 receives TA information for candidate cell 1 from terminal device 120. Candidate cell 1 does not belong to network device 100, and candidate cell 1 belongs to network device 300 or network device 400. When network device 100 receives TA information for candidate cell 1 from terminal device 120, the TA information for candidate cell 1 is TA information for terminal device 120. For example, terminal device 120 can, based on the TA of candidate cell 1, perform data transmission with network device 300 or network device 400 corresponding to candidate cell 1.

[00157] Note that candidate cell 1 can be cell #1 or cell #3.

[00158] In one possible implementation, network device 100 is a candidate DU and serves as a target DU for a first switch (the target DU is a DU corresponding to cell #2), network device 200 is a CU, network device 300 is a source DU for the first switch (the source DU is a DU corresponding to cell #1), and network device 400 is another candidate DU that does not serve as a target DU for the first switch (the other candidate DU is a DU corresponding to cell #3). For ease of understanding, an example is used below in which network device 100 is the target DU, network device 300 is the source DU, network device 200 is the CU, and network device 400 is the other candidate DU for description. The definition Petition 870250104098, dated 11 / 13 / 2025, p. 42 / 97 36 / 79 also applies to the following 500 method.

[00159] For a case where network device 100 receives TA information from candidate cell 1:

[00160] In a first possible implementation, when network device 100 (the target DU) receives information about the TA of candidate cell 1 from terminal device 120, network device 100 (the target DU) can send information to terminal device 120 indicating that it should report a TA from a candidate cell. Correspondingly, terminal device 120 determines whether to report information about the TA of candidate cell 1 from a plurality of candidate cells and reports the information about the TA of candidate cell 1 to network device 100 (the target DU). The plurality of candidate cells includes candidate cell 1.

[00161] Optionally, network device 100 (the target DU) can send information to terminal device 120 indicating to report the TA of candidate cell 1. Terminal device 120 reports the information about the TA of candidate cell 1 to network device 100 (the target DU) based on the indication.

[00162] In a second possible implementation, when network device 100 (the target DU) receives information about the TA of candidate cell 1 from terminal device 120, network device 100 (the target DU) can send information to terminal device 120 indicating to report the TA of candidate cell 1. Correspondingly, terminal device 120 reports the information about the TA of candidate cell 1 to network device 100 (the target DU).

[00163] In a third possible implementation, network device 100 (the target DU) receives information about the TA of candidate cell 1 from network device 200 (the CU), where candidate cell 1 belongs to network device 300 (the source DU) or to network device 400 (the other candidate DU). In one example, when candidate cell 1 belongs to the device Petition 870250104098, dated 11 / 13 / 2025, page 43 / 97 In a network device 300 (the source DU), network device 300 (the source DU) sends information about the TA of candidate cell 1 to network device 200 (the CU), and then network device 200 (the CU) sends information about the TA of candidate cell to network device 100 (the target DU). In another example, when candidate cell 1 belongs to network device 400 (the other candidate DU), network device 400 (the other candidate DU) sends information about the TA of candidate cell 1 to network device 200 (the CU), and then network device 200 (the CU) sends information about the TA of candidate cell to network device 100 (the target DU).

[00164] In a fourth possible implementation, when candidate cell 1 belongs to network device 400 (the other candidate DU), network device 400 (the other candidate DU) sends information about the TA of candidate cell 1 to network device 300 (the source DU) using network device 200 (the CU). Correspondingly, network device 300 (the source DU) sends information about the TA of candidate cell 1 to network device 100 (the target DU) using network device 200 (the CU).

[00165] S420: Network device 100 sends a target cell identifier 1 from a switch and indication information 1 to terminal device 120, where indication information 1 indicates access to target cell 1 in a random channel hopping manner, and target cell 1 is candidate cell 1.

[00166] Specifically, the target cell identifier 1 and the indication information 1 can be carried in an LTM command message. Specifically, network device 100 (the target DU) sends the LTM command message to terminal device 120, where the LTM command message includes the target cell identifier 1 and the indication information 1. The LTM command message can be an element Petition 870250104098, dated 11 / 13 / 2025, page 44 / 97 38 / 79 MAC control element (CE).

[00167] Optionally, the target cell identifier 1 and the indication information 1 can be carried in different messages.

[00168] Optionally, network device 100 (the target DU) can separately send the target cell identifier 1 and the indication information 1. For example, network device 100 sends an LTM command message to terminal device 120, where the LTM command message includes the target cell identifier 1. Additionally, network device 100 (the target DU) sends the indication information 1 to terminal device 120.

[00169] In one possible implementation, when network device 100 (the target DU) sends the LTM command message including the target switch cell identifier to terminal device 120, the following can be predefined: When the LTM command message excludes indication information indicating to initiate a contention-free random access procedure for the target cell, terminal device 120 is considered by default to access the target cell in the random access channel hopping manner.

[00170] In one possible implementation, when the LTM command message sent by network device 100 (the target DU) to terminal device 120 includes an indication field (which may be a newly added field) indicating access to the target cell in the random access channel-skip / less (RACH-SKIP / LESS) manner, terminal device 120 performs an operation based on the indication field.

[00171] Optionally, indication information 1 may further indicate to terminal device 120 to access target cell 1 in a non-random access channel manner.

[00172] It can be understood that the fact that network device 100 (the target DU) receives information about the TA from the cell Petition 870250104098, dated 11 / 13 / 2025, page 45 / 97 Candidate 1 (39 / 79) indicates that network device 100 (the target DU) determines that terminal device 120 and / or the network device (network device 300 or network device 400) corresponding to candidate cell 1 has / has the TA of candidate cell 1. Therefore, network device 100 (the target DU) determines, based on the information received about the TA of candidate cell 1, to send indication 1 to terminal device 120. In one possible implementation, indication 1 can be a TA of the target cell (terminal device 120 does not store the TA of the target cell) or a random access channel hop indication (terminal device 120 stores the TA of the target cell). Terminal device 120 can determine the TA of the target cell based on the information received about the TA of the target cell and does not need to obtain the TA of the target cell by initiating a random access procedure.Therefore, terminal device 120 can access the target cell in a random access channel hopping method.

[00173] Optionally, after receiving information about the TA of candidate cell 1, network device 100 (the target DU) determines that terminal device 120 and / or the network device corresponding to candidate cell 1 already has / has information about the TA of candidate cell 1. After network device 100 (the target DU) sends the LTM command message to terminal device 120, terminal device 120 does not need to be triggered to initiate the contention-free random access procedure to the target cell (i.e., candidate cell 1 serves as the target cell), to obtain the TA of candidate cell 1 again.

[00174] Optionally, network device 100 (the target DU) can also receive information about a TA from a candidate cell 2. Consequently, network device 100 (the target DU) does not need, based on the information obtained about the cell's TA. Petition 870250104098, dated 11 / 13 / 2025, page 46 / 97 40 / 79 candidate 2, trigger terminal device 120 to initiate a contention-free random access procedure for candidate cell 2 before switching, in order to obtain the TA of candidate cell 2 again. Therefore, the number of random access procedures that need to be initiated by terminal device 120 can be reduced. For a way in which network device 100 (the target DU) obtains information about the TA of candidate cell 2, refer to the previous way of obtaining information about the TA of candidate cell 1.

[00175] Optionally, network device 100 (the target DU) can simultaneously obtain TA information from candidate cell 1 and TA information from candidate cell 2.

[00176] In conclusion, network device 100 (the target DU) can determine, based on the information obtained about the TA of the candidate cell, that terminal device 120 does not need to be triggered to initiate a random access procedure for the candidate cell for which network device 100 obtained the TA information, in order to obtain the TA of the candidate cell. This can effectively reduce the number of random access procedures that need to be initiated by terminal device 120. Therefore, the power consumption and random access interference of terminal device 120 can be reduced.

[00177] In one possible implementation, the indication information 1 tells terminal device 120 to access target cell 1 in random access channel hopping mode. This may include: The indication information 1 tells terminal device 120 to perform data transmission on target cell 1 in random access channel hopping mode. In other words, after receiving the LTM command message, terminal device 120 does not need to initiate a random access procedure for candidate cell 1.

[00178] In one possible implementation, a function that Petition 870250104098, dated 11 / 13 / 2025, page 47 / 97 41 / 79 Indication Information 1 indicates to access target cell 1 in the random access channel hopping manner, which can be completed via Indication Information 1 or a specific information element within Indication Information 1. This is not limited.

[00179] In one possible implementation, candidate cell 1 could be a source service cell (e.g., cell #1) before an initial LTM switch (which is a first LTM switch) of terminal device 120, or it could be a candidate cell (e.g., cell #3) different from the source service cell before the initial LTM switch. For example, after the initial LTM switch is performed, terminal device 120 is switched from cell #1 (which is the source service cell) to cell #2 (which is the target cell).When network device 100 (the target DU) determines that terminal device 120 needs to be switched from cell #2 to cell #3 or cell #1 (cell #3 or cell #1 can be candidate cell 1), because network device 100 (the target DU) has obtained information about a TA from cell #3 or cell #1, network device 100 (the target DU) can send indication information 1 to terminal device 120.

[00180] In one possible implementation, network device 100 (the target DU) receives information about the TA of candidate cell 1 from terminal device 120, and method 400 may also include the following step.

[00181] S410a: Network device 100 (the target DU) sends indication information 2 to terminal device 120, where indication information 2 indicates (or is used to trigger) the candidate cell TA information report or candidate cell TA information 1.

[00182] Specifically, when indication information 2 indicates (or is used to trigger) the information report on Petition 870250104098, dated 11 / 13 / 2025, page 48 / 97 42 / 79 of the candidate cell TA, terminal device 120 can report TA information from a plurality of candidate cells to network device 100 (the target DU), where the plurality of candidate cells includes candidate cell 1. When indication information 2 indicates (or is used to trigger) the reporting of information about the candidate cell 1 TA, terminal device 120 reports the information about the candidate cell 1 TA to network device 100 (the target DU).

[00183] Optionally, when indication information 2 indicates (or is used to trigger) the information report about the TA of candidate cell 1, indication information 2 includes identification information of candidate cell 1. Terminal device 120 determines, based on the identification information of candidate cell 1 carried in indication information 2, the information report about the TA of candidate cell 1 to network device 100 (the target DU).

[00184] Optionally, when indication information 2 indicates (or is used to trigger) the reporting of information about the TA of the candidate cell, indication information 2 may not contain a candidate cell identifier, and terminal device 120 determines, from the plurality of candidate cells, to report the information about the TA of candidate cell 1 to network device 100 (the target DU). It can be understood that, for a process in which terminal device 120 determines the information about the TA of candidate cell 1, refer to the descriptions in FIG. 3.3. Details are not described again in this document.

[00185] In one possible implementation, network device 100 (the target DU) receives information about the TA of candidate cell 1 from network device 200 (the CU), and method 400 may also include the following step.

[00186] S410b: Network device 100 sends request information 1 to network device 200 (the CU), where the Petition 870250104098, dated 11 / 13 / 2025, page 49 / 97 43 / 79 request information 1 is used to request information about the TA of candidate cell 1 or candidate cell.

[00187] Correspondingly, network device 200 (the CU) receives request information 1 from network device 100 (the target DU) and sends information about the TA of candidate cell 1 to network device 100 (the target DU) based on request information 1.

[00188] Specifically, network device 200 (the CU) interacts with a network device (for example, network device 300 (the source DU) or network device 400 (the other candidate DU)) that has information about the TA of candidate cell 1, to obtain information about the TA of candidate cell 1 and sends information about the TA of candidate cell 1 to network device 100.

[00189] Specifically, when network device 100 (the target DU) obtains information about the TA of candidate cell 1 from network device 200 (the CU), network device 100 (the target DU) sends, using network device 200 (the CU), request information 1 to the network device (for example, network device 300 or network device 4) corresponding to candidate cell 1. Request information 1 is used to request information about the TA of candidate cell 1 and includes an identifier of candidate cell 1.

[00190] More specifically, for S410b, network device 110 (the target DU) requests network device 300 (the source DU) or network device 400 (the other candidate DU) for information about the TA of candidate cell 1 using network device 200 (the CU).

[00191] Optionally, the request information 1 includes the identification information of candidate cell 1. Network device 200 (the CU) determines, based on the identification information of candidate cell 1 contained in the request information, Petition 870250104098, dated 11 / 13 / 2025, page 50 / 97 44 / 79 request 1, send the request 1 information to network device 300 (the originating DU) or to network device 400 (the other candidate DU) corresponding to candidate cell 1.

[00192] Optionally, when request information 1 excludes candidate cell identification information, network device 200 (the CU) broadcasts request information 1, and a network device that receives request information 1 (for example, network device 300 or network device 4) responds to request information 1 and sends, to network device 100 (the target DU) using network device 200 (the CU), the information about the TA of the candidate cell that the network device already possesses.

[00193] Optionally, before switching terminal device 120 to candidate cell 1, network device 100 (the target DU) can also obtain TA information from candidate cell 2 and can further determine not to trigger a random access procedure for candidate cell 2. Candidate cell 2 is a different candidate cell from candidate cell 1 and can belong to network device 300 (the source DU) and can also belong to network device 400 (the other candidate DU). For descriptions of how to obtain TA information from candidate cell 2, see the descriptions of how to obtain TA information from candidate cell 1. The details are not described again.

[00194] In a possible implementation, the information about the TA of candidate cell 1 includes at least one of the following: the Candidate cell 1 time offset; indication information showing that candidate cell 1 time offset is valid; remaining valid time of candidate cell 1 time offset; and a time offset of candidate cell 1 time offset, where the time offset corresponds to the duration of candidate cell 1 time offset.

[00195] It can be understood that, when information about TA Petition 870250104098, dated 11 / 13 / 2025, page 51 / 97 45 / 79 of candidate cell 1 include the TA of candidate cell 1; the information about the TA of candidate cell 1 is an absolute TA value of candidate cell 1. Terminal device 120 can determine a TA for uplink transmission based on the absolute TA value of candidate cell 1.

[00196] Specifically, when the information about the TA of candidate cell 1 is the TA of candidate cell 1, network device 100 (the target DU) determines that terminal device 120 and / or the network device (which is network device 300 (the source DU) or network device 400 (the other candidate DU)) corresponding to candidate cell 1 has / has the TA of candidate cell 1. When the information about the TA of candidate cell is the indication that the TA of candidate cell 1 is valid, network device 100 determines that the TA of candidate cell 1 owned by terminal device 120 and / or the network device (which is network device 300 (the source DU) or network device 400 (the other candidate DU)) corresponding to candidate cell 1 is valid.When the information about the TA of candidate cell 1 is the remaining valid time of the TA of candidate cell 1, network device 100 (the target DU) determines the remaining valid time of the TA of candidate cell 1. If an LTM switch is performed within the remaining valid time, network device 100 (the target DU) does not need to indicate terminal device 120 to initiate the random access procedure for candidate cell 1. If the LTM switch is performed beyond the remaining valid time, network device 100 (the target DU) still needs to indicate terminal device 120 to initiate the random access procedure for candidate cell 1. When the information about the TA of candidate cell 1 is the time offset of the TA of candidate cell 1, network device 100 (the target DU) determines the elapsed time or the TA duration of candidate cell 1 based on the time offset. Network device 100 Petition 870250104098, dated 11 / 13 / 2025, page 52 / 97 46 / 79 (the target DU) can determine, based on the time offset, the time elapsed after the determination of the TA of the candidate cell. 1. Similarly, network device 100 (the target DU) determines, based on the time offset, whether terminal device 120 needs to be indicated to initiate the random access procedure for candidate cell 1.

[00197] Optionally, the TA of candidate cell 1 includes a valid TA and an invalid TA.

[00198] Optionally, network device 100 (the target DU) indicates to terminal device 120 that it should report the valid TA of candidate cell 1. Correspondingly, terminal device 120 reports the valid TA of candidate cell 1 to network device 100 (the target DU). Optionally, terminal device 120 may simultaneously report the valid and invalid TA of candidate cell 1 to network device 100 (the target DU). When terminal device 120 reports the valid TA of candidate cell 1 to network device 100 (the target DU), terminal device 120 may report remaining valid time, a time offset, or something similar from the valid TA to network device 100 (the target DU).

[00199] Optionally, when network device 100 (the target DU) tells terminal device 120 to report the TA of candidate cell 1, terminal device 120 reports the valid TA of candidate cell 1 to network device 100 (the target DU). Optionally, terminal device 120 can simultaneously report the valid and invalid TA of candidate cell 1 to network device 100 (the target DU). Optionally, when terminal device 120 reports the valid TA of candidate cell 1 to network device 100 (the target DU), terminal device 120 can report the remaining valid time, time offset, or similar of the valid TA to network device 100 (the target DU).

[00200] It should be noted that method 400 mainly involves interaction between the originating DU, the device Petition 870250104098, dated 11 / 13 / 2025, p. 53 / 97 4Ί / Ί9 terminal 120, the target DU, the other candidate DU, and the CU. Method 400 is described primarily using the target DU as the object to obtain information about the TA of candidate cell 1 and send indication information 1 to terminal device 120. A technical solution is described below in which terminal device 120 is used as the object, with reference to another attached drawing.

[00201] It should be noted that the source DU, the target DU, the other candidate DU, and the CU in method 400 can belong to the same base station. Furthermore, method 400 can be applied to a scenario of interaction between base stations. For example, the source DU and the CU belong to base station 1, and the target DU and the other candidate DU belong to base station 2. For a specific method, refer to the previous descriptions. Details are not described again in this document.

[00202] FIG. 5 is a schematic interaction flowchart of a 500 communication method according to an embodiment of this application. The 500 method can be implemented by a network device 100, a network device 300 and a terminal device 120, or it can be implemented by modules and / or components (e.g., chips or integrated circuits) installed in the network device 100, the network device 300 and the terminal device 120 and having corresponding functions. This is not limited to embodiments of this application. As shown in FIG. 5, the 500 method includes the following steps.

[00203] Optionally, in S510a, terminal device 120 receives indication information 2, where indication information 2 indicates reporting information about a TA of a candidate cell.

[00204] Specifically, terminal device 120 can receive indication information 2 from network device 100 (a target DU) or it can receive indication information 2 from network device 300 (a source DU). The candidate cell includes a candidate cell 1. The cell Petition 870250104098, dated 11 / 13 / 2025, page 54 / 97 Candidate 1, 48 / 79, does not belong to network device 100 (the target DU), and candidate cell 1 belongs to network device 300 (the source DU) or to a network device 400 (another candidate DU).

[00205] In one example, after terminal device 120 is switched to a candidate cell 2 managed by network device 100 (the target DU), network device 100 (the target DU) sends indication information 2 to terminal device 120, where indication information 2 tells terminal device 120 to report the TA information of the candidate cell.

[00206] In one example, when network device 300 (the source DU) determines that terminal device 120 needs to be switched to candidate cell 2 managed by network device 100 (the target DU), an LTM command sent by network device 300 (the source DU) to terminal device 120 includes indication information 2 and an identifier of a target cell from a switch, where the target cell is candidate cell 2 (this is an initial LTM switch). Terminal device 120 determines, based on the LTM command, that information about the TA of the candidate cell needs to be reported to network device 100 (the target DU). For descriptions of sending indication information 2 by the network device 300 (the originating DU) to terminal device 120, see previous descriptions. Details are not described again in this document.

[00207] According to the previous technical solution, terminal device 120 reports information about the TA of the candidate cell based on an indication of indication information 2. This helps to improve the efficiency of information exchange between terminal device 120 and the network device.

[00208] S510: Terminal device 120 determines information about a TA of candidate cell 1.

[00209] Specifically, terminal device 120 sends a Petition 870250104098, dated 11 / 13 / 2025, page 55 / 97 49 / 79 Contention-free random access preamble in candidate cell 1. Correspondingly, network device 300 (the originating DU) or network device 400 (the other candidate DU) receives the contention-free random access preamble from candidate cell 1 and further determines the TA of candidate cell 1. Additionally, network device 300 (the originating DU) or network device 400 (the other candidate DU) sends a RAR message to terminal device 120, where the RAR message includes the TA of candidate cell 1. In this way, terminal device 120 can determine the TA of candidate cell 1 according to the previous method.

[00210] Optionally, terminal device 120 and / or a network device that has information about the TA of candidate cell 1 can determine information such as valid information, remaining valid time, or a time offset of the TA of candidate cell 1.

[00211] S520: Terminal device 120 reports TA information from candidate cell 1 to network device 100 (the target DU).

[00212] Specifically, when indication information 2 indicates to report TA information of the candidate cell, terminal device 120 can report TA information of a plurality of candidate cells to network device 100 (the target DU), where the plurality of candidate cells includes candidate cell 1. For descriptions of candidate cell 1, see method 400. Details are not described again in this document.

[00213] Specifically, terminal device 120 reports information about the TA of candidate cell 1 to network device 100 (the target DU), so that network device 100 (the target DU) obtains information about the TA of candidate cell 1. Correspondingly, network device 100 (the target DU) can determine, based on the information about the TA of the candidate cell Petition 870250104098, dated 11 / 13 / 2025, pp. 56 / 97 50 / 79 1. If terminal device 120 needs to be triggered to initiate a random access procedure for candidate cell 1, when network device 100 (the target DU) determines that terminal device 120 does not need to be triggered to initiate the random access procedure for candidate cell 1, the number of random access procedures that need to be initiated by the terminal device can be effectively reduced.

[00214] Optionally, network device 100 (the target DU) can also receive information about a TA from candidate cell 3. Network device 100 (the target DU) does not need to trigger terminal device 120 to initiate a random access procedure for candidate cell 3 based on the information obtained about the TA of candidate cell 3. This can reduce the number of random access procedures that need to be initiated by terminal device 120.

[00215] In conclusion, network device 100 (the target DU) can determine, based on the information obtained about the TA of the candidate cell, that terminal device 120 does not need to be triggered to initiate a random access procedure for the candidate cell for which network device 100 (the target DU) obtained the TA information. This can effectively reduce the number of random access procedures that need to be initiated by terminal device 120. Therefore, the power consumption and random access interference of terminal device 120 can be reduced.

[00216] Note that for descriptions of the TA information for candidate cell 1 in method 500, see method 400. Details are not described again in this document.

[00217] It should be noted that method 500 primarily involves interaction between the source DU, the terminal device 120, the target DU, and another candidate DU. Method 500 is mainly described using a theme in which the device Petition 870250104098, dated 11 / 13 / 2025, p. 57 / 97 Terminal 120, 51 / 79, determines and reports information about the TA of candidate cell 1.

[00218] It should be noted that the source DU, the target DU, the other candidate DU, and the CU in method 500 can belong to the same base station. Furthermore, method 500 can be applied to a scenario of interaction between base stations. For example, the source DU and the CU belong to base station 1, and the target DU and the other candidate DU belong to base station 2. For a specific method, see the previous descriptions. Details are not described again in this document.

[00219] It should also be noted that the 500 method can be a side method of the 400 method.

[00220] Method 400 and method 500 are described in more detail below with reference to FIG. 6A to FIG. 8B.

[00221] It should be noted that the methods shown in FIGS. 6A to 8B are additional descriptions of method 400 and method 500. Furthermore, the methods shown in FIGS. 6A to 8B can also be understood as supplementary descriptions of method 400 and method 500. A DU 1 is network device 300, a DU 2 is network device 100, a DU 3 is network device 400, and a CU is network device 200.

[00222] FIG. 6A and FIG. 6B are a schematic interaction flowchart of a communication method 600 according to an embodiment of this application; The method 600 can be implemented by a terminal device 120, a DU 1, a DU 2, a DU 3 and a CU, or it can be implemented by modules and / or components (e.g., chips or integrated circuits) that are installed in the terminal device 120, in the DU 1, in the DU 2, in the DU 3 and in the CU and that have corresponding functions. This is not limited to embodiments of this application. The following is an example in which the method 600 is implemented by the terminal device 120, by the DU 1, by the DU 2, by the DU 3 and by the CU for descriptive purposes. As shown in In FIG. 6A and FIG. 6B, method 600 includes the following steps. Petition 870250104098, dated 11 / 13 / 2025, p. 58 / 97 52 / 79

[00223] S610: Terminal device 120 sends measurement report information to DU1.

[00224] S620: DU 1 sends a UL RRC message transfer message to aCU.

[00225] S630: CU determines to initiate an LTM configuration procedure.

[00226] For descriptions of S610 to S630, see the previous descriptions of S310 to S330. Details are not described again in this document.

[00227] S640: CU 1 sends a UE context configuration request message to DU 2.

[00228] Optionally, CU 1 can also send a request message for EU context configuration to DU 3.

[00229] S650: DU 2 sends a UE context configuration response message to CU.

[00230] Optionally, DU 3 can also send an EU context configuration response message to the UC.

[00231] For descriptions of S640 and S650, see the previous descriptions of S340 and S350. Details are not described again in this document.

[00232] Optionally, the CU may request, via a UE context configuration request message, LTM configuration procedures from candidate cells managed by DU 2 and DU 3, or each candidate cell has a UE context configuration request message.

[00233] S660: CU 1 sends a DL RRC message transfer message to DU 1.

[00234] S670: DU 1 sends an RRCReconfiguration message to terminal device 120.

[00235] S680: Terminal device 120 sends a message RRCReconfigurationComplete for DU 1.

[00236] S690: DU 1 sends the message RRCReconfigurationComplete for CU1 through information from Petition 870250104098, dated 11 / 13 / 2025, page 59 / 97 53 / 79 UL RRC.

[00237] For descriptions of S660 to S690, see the previous descriptions of S360 to S390. Details are not described again in this document.

[00238] It should be noted that terminal device 120 and DU 1 maintain a TA for a service cell group, and the service cell group includes at least one service cell. All service cells in the service cell group correspond to the same TA and store the most recent TA value used by terminal device 120 to determine the TA for sending uplink transmission in the service cell. All service cells in the service cell group belong to DU 1. The TA of the service cell group is determined using a downlink reference signal from a secondary timing advance group (STAG) of one of the service cells or a primary timing advance group (PTAG) of a current carrier aggregation (CA) primary cell as a reference for the TA.

[00239] Note that terminal device 120 does not need to detect a DU, but only a candidate cell. The DU can detect whether the candidate cell belongs to the DU.

[00240] S6100: DU 1 sends command 1 and command 2 to terminal device 120.

[00241] Correspondingly, terminal device 120 receives command 1 and command 2 from DU 1. Command 1 is used to instruct or trigger terminal device 120 to send a contention-free random access preamble 1 to a candidate cell 1, and the contention-free random access preamble 1 is used to determine a TA of candidate cell 1. Command 2 is used to instruct or trigger terminal device 120 to send a contention-free random access preamble 2 to a candidate cell 2, and the contention-free random access preamble 1 is used to determine a TA of candidate cell 1. Petition 870250104098, dated 11 / 13 / 2025, pp. 60 / 97 The random 54 / 79 containment-free array 2 is used to determine a TA of candidate cell 2. Command 1 includes an identifier for candidate cell 1, and command 2 includes an identifier for candidate cell 2.

[00242] It can be understood that DU 1 can send both command 1 and command 2 to terminal device 120, in other words, trigger terminal device 120 to initiate a random access procedure for candidate cell 1 and candidate cell 2. Therefore, S6100 is used only as an example for understanding.

[00243] It can be understood that command 1 includes contention-free random access configuration information 1 used to send contention-free random access preamble 1, and command 2 includes contention-free random access configuration information 2 used to send contention-free random access preamble 2. Candidate cell 2 belongs to DU 2, and candidate cell 1 belongs to DU 3.

[00244] S6110a: Terminal device 120 sends contention-free random access preamble 1 to candidate cell 2.

[00245] Correspondingly, DU 2 receives the contention-free random access preamble 1 from terminal device 120 and determines the TA of candidate cell 2 based on the contention-free random access preamble 1.

[00246] S6110b: Terminal device 120 sends contention-free random access preamble 2 to candidate cell 1.

[00247] Correspondingly, DU 3 receives the contention-free random access preamble 2 from terminal device 120 and determines the TA of candidate cell 1 based on the contention-free random access preamble 2.

[00248] Optionally, in S6120a, DU 2 sends a RAR 1 message to terminal device 120.

[00249] Correspondingly, terminal device 120 receives the RAR 1 message from DU 2. The RAR message Petition 870250104098, dated 11 / 13 / 2025, pp. 61 / 97 55 / 79 includes the TA of candidate cell 2. The TA of candidate cell 2 is an absolute TA value. Terminal device 120 can determine, based on the absolute TA value of candidate cell 2, an advance in the uplink transmission time of the uplink transmission in candidate cell 2.

[00250] Optionally, in S6120b, DU 3 sends a RAR 2 message to terminal device 120.

[00251] Correspondingly, terminal device 120 receives the RAR 2 message from DU 3. The RAR 2 message includes the TA of candidate cell 1. The TA of candidate cell 1 is an absolute TA value. Terminal device 120 can determine, based on the absolute TA value of candidate cell 1, an advance in the uplink transmission time of candidate cell 1.

[00252] When using S6110 to S6120, terminal device 120 completes random access procedures for candidate cell 1 and candidate cell 2 and obtains the TA of candidate cell 1 and the TA of candidate cell 2.

[00253] S6130: Terminal device 120 sends a measurement report from candidate cell 2 to DU 1.

[00254] Correspondingly, DU 1 receives the measurement report from candidate cell 2 from the terminal device. 120.

[00255] S6140: DU 1 determines that the terminal device 120 should be switched to candidate cell 2.

[00256] S6150: DU 1 sends an LTM 1 command to terminal device 120.

[00257] Correspondingly, terminal device 120 receives the LTM 1 command. The LTM 1 command includes an identifier for a target cell.

[00258] S6160: DU 1 sends signal 1 to CU.

[00259] Correspondingly, CU receives signal 1 from DU 1. Signal 1 includes information about a TA of Petition 870250104098, dated 11 / 13 / 2025, pp. 62 / 97 56 / 79 a service cell of origin.

[00260] Optionally, signaling 1 may also include information about the TA of candidate cell 1.

[00261] More specifically, DU 3 can send TA information from candidate cell 1 to DU 1 using CU.

[00262] Optionally, DU 1 can determine the validity of the TA of the originating service cell using a timing advance timer (TAT). Optionally, DU can also determine the validity of the TA of candidate cell 1 using the TAT.

[00263] S6170: CU sends signal 2 to DU 2.

[00264] Correspondingly, DU 2 receives signaling 2 from CU. Signaling 2 includes information about the TA of the originating service cell and information about the TA of candidate cell 1.

[00265] S6180: Terminal device 120 sends an initial message to DU 2.

[00266] Correspondingly, DU 2 receives the initial message from terminal device 120. The initial message is a first message to switch to the target cell, is used to request access to the target cell and includes an RRCReconfigurationComplete message, a cell-radio network temporary identifier (CRNTI) or other content.

[00267] Furthermore, DU 2 determines, based on the initial message, that terminal device 120 successfully accesses candidate cell 2.

[00268] S6190: DU 2 sends a successful access message to CU.

[00269] Correspondingly, the CU receives the successful access message from DU 2.

[00270] Specifically, after DU 2 determined that terminal device 120 had been successfully switched to cell Petition 870250104098, dated 11 / 13 / 2025, pp. 63 / 97 57 / 79 candidate 2, DU 2 can send the access success message to the CU, including the target cell identifier. Furthermore, the CU determines, based on the target cell identifier contained in the access success message, that terminal device 120 was successfully switched to candidate cell 2.

[00271] After terminal device 120 is switched to candidate cell 2, DU 2 determines, based on TA information, not to perform random access procedures to the source service cell and candidate cell 1 before a subsequent switch.

[00272] In addition, DU 2 sends an LTM command to terminal device 120, where the LTM command includes the target cell identifier and indication information 1. Terminal device 120 accesses the target cell in a random access channel hopping manner, based on the LTM command, and transmits uplink data based on a TA from the target cell. For the content of this part, refer to the previous descriptions.

[00273] Optionally, DU 2 can receive additional information about a TA from a candidate cell 3. Based on the information obtained about the TA of candidate cell 3 (candidate cell 3 belongs to DU 3, not shown in FIG. 6A and FIG. 6B), DU 2 does not need to trigger terminal device 120 to initiate a random access procedure for the candidate cell in which the TA information was obtained. This reduces the number of random access procedures that need to be initiated by terminal device 120.

[00274] In conclusion, DU 2 can determine, based on the information obtained about the TA of the candidate cell, that terminal device 120 does not need to be triggered to initiate the random access procedure for the candidate cell for which the TA information was obtained. This can effectively reduce the number of random access procedures. Petition 870250104098, dated 11 / 13 / 2025, pp. 64 / 97 58 / 79 that need to be initiated by terminal device 120. Therefore, the power consumption and random access interference of terminal device 120 can be reduced. For descriptions of the TA information, see the previous descriptions. Details are not described again in this document.

[00275] According to the technical solution above, in this application, DU 2 obtains information about the TAs of a plurality of candidate cells from the CU and determines, based on the information about the TAs of the plurality of candidate cells, that terminal device 120 does not need to be triggered to initiate random access procedures for the plurality of candidate cells. Therefore, the number of random access procedures initiated by terminal device 120 can be reduced, and the power consumption of terminal device 120 as well.

[00276] It should be noted that the message names above are used only as descriptive examples and not as a final limitation. A message name that has a similar or identical function and that is used in a future standard may be used. This is described uniformly in this document. The details will not be described again below.

[00277] It should be noted that some of the above procedures may be optional and unnecessary. For example, DU 1 only instructs terminal device 120 to send contention-free random access preamble 1 to DU 2, but does not instruct terminal device 120 to send contention-free random access preamble 2 to DU 3. For example, DU 1 only sends command 1 to terminal device 120.

[00278] It should be noted that method 600 can additionally be applied to a base station interaction scenario. For example, DU 1 and CU belong to base station 1, and DU 2 and DU 3 belong to base station 2. For a base station interaction method, see the interaction method. Petition 870250104098, dated 11 / 13 / 2025, p. 65 / 97 59 / 79 inside the base station. Details are not described again in this document.

[00279] When method 600 is applied to the base station interaction scenario, the message name above may be changed. For example, the UE context configuration request message is changed to an HO (handover) request, and the UE context configuration response message is changed to an HO response.

[00280] FIG. 7A and FIG. 7B are a schematic interaction flowchart of a communication method 700 according to an embodiment of this application; The method 700 can be implemented by a terminal device 120, a DU 1, a DU 2, a DU 3 and a CU, or it can be implemented by modules and / or components (e.g., chips or integrated circuits) that are installed in the terminal device 120, in the DU 1, in the DU 2, in the DU 3 and in the CU and that have corresponding functions. This is not limited to embodiments of this application. As shown in FIG. 7A and FIG. 7B, the method 700 includes the following steps.

[00281] For S710 to S7150, see descriptions of S610 to S6150. Details are not described again in this document.

[00282] S7160: CU sends request information to DU 1.

[00283] Correspondingly, DU 1 receives the request information from CU, where the request information is used to request information about a TA from at least one originating service cell and one candidate cell. 1.

[00284] Optionally, DU 1 can determine the validity of a TA from the originating service cell using a TAT.

[00285] Optionally, DU 3 can also determine the validity of the TA of candidate cell 1 using the TAT.

[00286] For S7170 to S7200, see descriptions of S6160 to S6190. Details are not described again in this document. Petition 870250104098, dated 11 / 13 / 2025, pp. 66 / 97 60 / 79

[00287] After terminal device 120 is switched to candidate cell 2, DU 2 does not need to trigger, based on TA information, terminal device 120 to initiate random access procedures to the source service cell and candidate cell 1. When DU 2 determines that terminal device 120 is switched to candidate cell 1, DU 2 instructs terminal device 120 to access candidate cell 1 in such a way that the random access channel is bypassed.

[00288] Correspondingly, DU 2 sends an LTM command to terminal device 120, where the LTM command includes an identifier of a target cell of a switch and indication information 1. Terminal device 120 accesses the target cell in random access channel hopping mode based on the LTM command and can transmit uplink data based on a TA of the target cell. For the content of this part, refer to the previous descriptions.

[00289] For descriptions of the information regarding TA, please refer to the previous descriptions. Details are not described again in this document.

[00290] In method 700, this request is described using an example in which the CU obtains TA information from at least one of the source service cells and candidate cell 1 by sending the request information to DU 1. However, a scenario in which the CU sends the request information to DU 1 to obtain TA information from the source service cell or TA information from candidate cell 1 is not limited.

[00291] According to the technical solution above, in this application, DU 2 obtains information about TAs from a plurality of candidate cells from the CU and determines, based on the information about the TAs, that terminal device 120 does not need to be triggered to initiate random access procedures for the plurality of candidate cells. Therefore, a quantity of Petition 870250104098, dated 11 / 13 / 2025, pp. 67 / 97 The number of random access procedures initiated by terminal device 120 can be reduced, as can the power consumption of terminal device 120.

[00292] Note that method 700 can be additionally applied to a base station interaction scenario. For example, DU 1 and CU belong to base station 1, and DU 2 and DU 3 belong to base station 2. For a base station interaction method, see the base station interaction method. Details are not described again in this document.

[00293] When method 700 is applied to the base station interaction scenario, the name of the message above may be changed. For example, a UE context configuration request message is changed to an HO request, and a UE context configuration response message is changed to an HO response.

[00294] FIG. 8A and FIG. 8B are a schematic interaction flowchart of an 800 communication method according to an embodiment of this application; The 800 method can be implemented by a terminal device 120, a DU 1, a DU 2, a DU 3 and a CU, or it can be implemented by modules and / or components (e.g., chips or integrated circuits) that are installed in the terminal device 120, in the DU 1, in the DU 2, in the DU 3 and in the CU and that have corresponding functions. This is not limited to embodiments of this application. As shown in FIG. 8A and FIG. 8B, the 800 method includes the following steps.

[00295] For S810 to S8150, see descriptions of S610 to S6150. Details are not described again in this document.

[00296] S8160: Terminal device 120 sends an initial message to DU 2.

[00297] S8170: DU 2 sends indication information 2 to terminal device 120.

[00298] S8180: Terminal device 120 sends information Petition 870250104098, dated 11 / 13 / 2025, pp. 68 / 97 62 / 79 on a TA of a candidate cell 1 for DU 2.

[00299] After terminal device 120 is switched to candidate cell 2, DU 2 does not need to trigger, based on TA information, terminal device 120 to initiate random access procedures to a source service cell and candidate cell 1. When DU 2 determines that terminal device 120 is switched to candidate cell 1, DU 2 instructs terminal device 120 to access candidate cell 1 in such a way that the random access channel is bypassed.

[00300] Correspondingly, DU 2 sends an LTM command to terminal device 120, where the LTM command may include an identifier of a target cell of a switch and an indication message 2. Terminal device 120 determines, based on the LTM command, access to the target cell in the random access channel hopping manner, and may transmit uplink data based on a TA of the source service cell or the TA of candidate cell 1. For the content of this part, refer to the previous descriptions. Details are not described again in this document.

[00301] For descriptions of the TA information, please refer to the previous descriptions. Details are not described again in this document.

[00302] S8190: DU 2 sends a successful access message to CU.

[00303] In method 800, this request is described using an example in which DU 2 obtains TA information from candidate cell 1 (or may obtain TA information from the source service cell) from terminal device 120. However, a scenario in which DU 2 obtains TA information from the service cell of terminal device 120 is not limited.

[00304] According to the technical solution above, in this application, DU 2 obtains information on the TAs from a plurality of Petition 870250104098, dated 11 / 13 / 2025, pp. 69 / 97 63 / 79 candidate cells of terminal device 120 and determines, based on information about the TAs, that terminal device 120 does not need to be triggered to initiate random access procedures for the plurality of candidate cells. Therefore, the number of random access procedures initiated by terminal device 120 can be reduced, and the power consumption of terminal device 120 as well.

[00305] Note that method 800 can be additionally applied to a base station interaction scenario. For example, DU 1 and CU belong to base station 1, and DU 2 and DU 3 belong to base station 2. For a base station interaction method, see the base station interaction method. Details are not described again in this document.

[00306] When method 800 is applied to the base station interaction scenario, the name of the message above may be changed. For example, a UE context configuration request message is changed to an HO request, and a UE context configuration response message is changed to an HO response.

[00307] The preceding describes the method modalities in modalities of this application, and the following describes corresponding apparatus modalities.

[00308] To implement functions in the methods provided in embodiments of this application, a terminal and a network device may each include a hardware structure and / or a software module to implement the functions in the form of the hardware structure, the software module, or a combination of the hardware structure and the software module. The execution of a function in the form of the hardware structure, the software module, or a combination of the hardware structure and the software module depends on the specific applications and design constraints of the technical solutions. Petition 870250104098, dated 11 / 13 / 2025, pp. 70 / 97 64 / 79

[00309] FIG. 9 is a block diagram of a 900 communication device according to an embodiment of this application. The 900 communication device may be the network device or the terminal device in the preceding embodiments, or it may be a chip or a module in the network device or the terminal device, and is configured to implement the methods in the preceding embodiments. The 900 communication device includes a 910 transceiver module. The 910 transceiver module is described below using an example.

[00310] The 910 transceiver module may include a transmit module and a receive module, configured respectively to implement a transmit function or a receive function in the previous method modes. The 900 communication device may also include a processing module, configured to implement a function other than transmit or receive.

[00311] When the communication device 900 is configured to implement a network device function, for example, the transceiver module 910 is configured to receive information about a TA from a candidate cell 1, and the transceiver module 910 is further configured to send, to a terminal device 120, an identifier of a target cell 1 of a switch, indication information 1 and the like.

[00312] Optionally, the communication device 900 may also include the processing module 920. The processing module 920 is configured to perform a function other than the receiving and sending functions, for example, determining the indication information 1.

[00313] Optionally, the communication device 900 also includes a storage module 930 (not shown in FIG. 9). The storage module 930 is configured to store a program or code used to perform the previous method.

[00314] The content is used for example purposes only. When the 900 communication device is configured to Petition 870250104098, dated 11 / 13 / 2025, pp. 71 / 97 65 / 79 to implement the network device, the communication device 900 is responsible for carrying out the method or steps related to the network device in the previous method mode.

[00315] The communication device 900 is a terminal device 120. For example, the transceiver module 910 is configured to report information about a TA from a candidate cell 1 to a network device.

[00316] It should be understood that when the communication device 900 is the terminal device 120, the transceiver module 910 may be a module that is in a control unit / subscriber unit / distributed unit of the terminal device 120 and that is configured to implement the receive and send functions.

[00317] Optionally, the communication device 900 may also include the processing module 920. The processing module 920 is configured to perform a function other than the receiving and sending functions, for example, determining the TA information of candidate cell 1.

[00318] Optionally, the communication device 900 also includes a storage module 930 (not shown in FIG. 9). The storage module 930 is configured to store a program or code used to perform the previous method.

[00319] The content is used for example purposes only. When communication device 900 is configured to implement a function of terminal device 120, communication device 900 is responsible for performing the method or steps related to terminal device 120 in the previous method mode.

[00320] In addition, for the implementation of each operation in FIG. 9, refer to the corresponding descriptions of the content shown in the previous method embodiment. Details are not described again in this document.

[00321] FIG. 10 is a block diagram of a device of Petition 870250104098, dated 11 / 13 / 2025, pp. 72 / 97 66 / 79 communication 1000 according to an embodiment of this application. The communication apparatus 1000 includes a processor 1010 and a communication interface 1020. The processor 1010 and the communication interface 1020 can be connected to each other via a bus 1040 (which is not shown in FIG. 10). The communication apparatus 1000 can be configured to implement a terminal device function and can also be configured to implement a network device function.

[00322] Optionally, the communication device 1000 also includes a memory 1030.

[00323] 1030 memory includes, but is not limited to, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), or compact disc read-only memory (CD-ROM). Memory is any other medium that can be configured to carry or store expected program code in the form of an instruction or data structure and that can be accessed by a computer, but is not limited to that. For example, 1030 memory is configured to store instructions and related data.

[00324] In this embodiment of this application, the processor may be a general-purpose processor, a digital signal processor, an application-specific integrated circuit, a field-programmable gate array or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component, and may implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this application. The general-purpose processor may be a microprocessor or any conventional or similar processor. The steps of the method disclosed with reference to the embodiments of this application may be completed directly by a Petition 870250104098, dated 11 / 13 / 2025, pp. 73 / 97 6Ί / Ί9 hardware processors can be implemented using a combination of hardware in the processor and a software module. For example, the 1010 processor can be one or more central processing units (CPUs). When the 1010 processor is a CPU, the CPU can be a single-core CPU or it can be a multi-core CPU.

[00325] When communication device 1000 is configured to implement a function of a terminal device 120, for example, processor 1010 is configured to perform the following operations: determine information about a TA of a candidate cell 1; and report the information about the TA of candidate cell 1 to a network device.

[00326] The content is used for example purposes only. When communication device 1000 is configured to implement the function of terminal device 120, communication device 1000 is responsible for performing the method or steps related to terminal device 120 in the previous method mode. [0032Ί] When the communication device 1000 is configured to implement the network device function, for example, the processor 1010 is configured to perform the following operations: receive information about a TA from a candidate cell 1; and send an identifier of a target cell 1 from a switch and indication information 1 to a terminal device 120.

[00328] The content is used for example purposes only. When communication device 1000 is configured to implement the network device function, communication device 1000 is responsible for performing the method or steps related to the network device in the previous method mode.

[00329] The previous descriptions are merely examples. For specific content, see the content shown in the method section. Furthermore, for the Petition 870250104098, dated 11 / 13 / 2025, pp. 74 / 97 68 / 79 implementation of each operation in FIG. 10, refer to the corresponding descriptions of the method embodiment shown in FIG. 3.

[00330] The communication apparatus shown in FIG. 9 and FIG. 10 is configured to implement the content described in the previous method embodiments. Therefore, for specific implementation steps and methods for the communication apparatus shown in FIG. 9 and FIG. 10, refer to the content described in the previous method embodiments.

[00331] It should be understood that the above transceiver module may include a transmit module and a receive module. The transmit module is configured to perform a transmit action from the communication device, and the receive module is configured to perform a receive action from the communication device. For ease of description, the transmit module and the receive module are combined into a single transceiver module in the embodiments of this application. Unified descriptions are provided here. The details will not be described again below.

[00332] FIG. 11 is a diagram of a communication device 1100 according to an embodiment of this application. The communication device 1100 can be configured to implement a function of the network device or terminal device in the previous method. The communication device 1100 can be a chip in the network device or terminal device. The communication device 1100 includes an input / output interface 1120 and a processor 1110. The input / output interface 1120 can be an input / output circuit. The processor 1110 can be a signal processor, a chip, or other integrated circuit that can implement the methods in this application. The input / output interface 1120 is configured for input or output of a signal or data.

[00333] For example, communication device 1100 is a terminal device 120, and the input / output interface 1120 is configured to report information about a TA from a cell. Petition 870250104098, dated 11 / 13 / 2025, pp. 75 / 97 69 / 79 candidate 1 for a network device. Processor 1111 is configured to determine the TA information of candidate cell 1. Processor 1111 is further configured to perform some or all of the steps of any method provided in this application.

[00334] For example, communication device 1100 is the network device, and input / output interface 1120 is configured to send an identifier of a target cell 1 of a switch, indication information 1 and the like to a terminal device 120.

[00335] In one possible implementation, processor 1111 executes instructions stored in memory, to implement the function implemented by terminal device 120 or by the network device.

[00336] Optionally, the 1100 communication device also includes memory. Optionally, the processor and memory are integrated. Optionally, the memory is located outside the 1100 communication device.

[00337] In one possible implementation, processor 1111 may be a logic circuit, and processor 1111 emits a message or signal via input / output interface 1120. The logic circuit may be a signal processor, a chip, or other integrated circuit that may implement the methods in embodiments of this application.

[00338] The previous descriptions of the 1100 communication apparatus in FIG. 11 are merely illustrative. The 1100 communication apparatus can be configured to perform the methods in the previous embodiments. For specific content, refer to the descriptions of the previous method embodiments. Details are not described again in this document.

[00339] FIG. 12 is a block diagram of a 1200 communication device according to an embodiment of this application. The 1200 communication device may be a network device or Petition 870250104098, dated 11 / 13 / 2025, pp. 76 / 97 70 / 79 could be a chip. The 1200 communication device can be configured to perform the above operations performed by the network device.

[00340] When the 1200 communication device is the network device, for example, a base station, FIG. 12 is a diagram of a simplified structure of the base station. The base station includes a 1210 module, a 1220 module, and a 1230 module. The CU 1210 is mainly configured to: perform baseband processing, control the base station, and the like. The 1210 module is generally a control center for the base station, commonly called a processor, and is configured to control the base station to perform a processing operation on a network device in the manner of the previous method. The 1220 module is mainly configured to store computer program code and data. The 1230 module is mainly configured to receive and send a radio frequency signal and perform conversion between the radio frequency signal and a baseband signal.The 1230 module may be commonly referred to as a transceiver module, transceiver circuit, transceiver, or similar terms. A transceiver module within the 1230 module may also be referred to as a transceiver or similar, and includes an antenna 1233 and a radio frequency circuit (not shown in FIG. 12), where the radio frequency circuit is primarily configured to perform radio frequency processing. Optionally, a component configured to implement a receiving function within the 1230 module may be considered a receiver, and a component configured to implement a sending function may be considered a transmitter. In other words, the 1230 module includes a receiver 1232 and a transmitter 1231. The receiver may also be referred to as a receiver module, receiving machine, receiver circuit, or similar, and the transmitter may be referred to as a transmitting module, transmitting machine, or circuit. Petition 870250104098, dated 11 / 13 / 2025, pp. 77 / 97 71 / 79 transmission or similar.

[00341] The 1210 module and the 1220 module may include one or more boards, and each board may include one or more processors and one or more memories. The processor is configured to read and execute a program in memory, implement a baseband processing function, and control the base station. If there is a plurality of boards, they may be interconnected to enhance processing capacity. In an optional implementation, the plurality of boards may share one or more processors, the plurality of boards may share one or more memories, or the plurality of boards may share one or more processors simultaneously.

[00342] In one implementation, the transceiver module in module 1230 is configured to perform a process related to receiving and sending, carried out by the network device in the modes shown in FIGS. 4 to 8B. The processor in module 1210 is configured to perform a process related to processing, carried out by the network device in the modes shown in FIGS. 4 to 8B.

[00343] In another implementation, the processor in module 1210 is configured to perform a process related to the processing performed by the network device in the modes shown in FIG. 4 to FIG. 8B.

[00344] In another implementation, the transceiver module in module 1230 is configured to perform a process related to receiving and sending data performed by the network device in the modes shown in FIG. 4 to FIG. 8B.

[00345] It should be understood that FIG. 12 is merely an example and not a limitation, and the previous access network device, including the processor, memory and transceiver, may not depend on the structures shown in FIGS. 9 to 11.

[00346] When the 1200 communication device is the chip, the chip includes a transceiver, memory, and a processor. The Petition 870250104098, dated 11 / 13 / 2025, pp. 78 / 97 72 / 79 The transceiver can be an input / output circuit or a communication interface. The processor is a processor, a microprocessor, or an integrated circuit integrated into the chip. A send operation performed by the network device in the previous method modes can be understood as an output of the chip, and a receive operation performed by the network device in the previous method modes can be understood as an input of the chip.

[00347] FIG. 13 is a block diagram of a 1300 communication device according to an embodiment of this application. The 1300 communication device can be a terminal device, a terminal device processor, or a chip. The 1300 communication device can be configured to perform the operations performed by the terminal device in the previous method embodiments.

[00348] When the communication device 1300 is the terminal device, FIG. 13 is a diagram of a simplified structure of the terminal device. As shown in FIG. 13, the terminal device includes a processor, a memory, and a transceiver. The memory can store computer program code. The transceiver includes a transmitter 1331, a receiver 1332, a radio frequency circuit (not shown in FIG. 13), an antenna 1333, and an input / output device (not shown in FIG. 13).

[00349] The processor is primarily configured to process a communication protocol and communication data, control the terminal device, execute a software program, process software program data, and the like. The memory is primarily configured to store the software program and data. The radio frequency circuit is primarily configured to perform conversion between a baseband signal and a radio frequency signal and to process the radio frequency signal. The antenna is primarily configured to Petition 870250104098, dated 11 / 13 / 2025, pp. 79 / 97 73 / 79 receive and send a radio frequency signal in the form of an electromagnetic wave. The input / output device, for example, a touch screen, a display, or a keyboard, is primarily configured to receive data entered by a user and to transmit data to the user. It should be noted that some types of terminal devices may not have input / output devices.

[00350] When data needs to be sent, after performing baseband processing on the data to be sent, the processor emits a baseband signal to the radio frequency circuit; and the radio frequency circuit performs radio frequency processing on the baseband signal and then sends the radio frequency signal to the outside in the form of an electromagnetic wave through the antenna. When the data is sent to the terminal device, the radio frequency circuit receives a radio frequency signal through the antenna, converts the radio frequency signal into a baseband signal, and emits the baseband signal to the processor. The processor converts the baseband signal into data and processes the data. For ease of description, FIG. 13 shows only one memory, one processor, and one transceiver. In a real terminal device product, there may be one or more processors and one or more memories.Memory can also be referred to as a storage medium, a storage device, or similar terms. Memory can be located independently of the processor or it can be integrated into the processor. This is not limited to the specific applications of this term.

[00351] In this embodiment of this application, the antenna and the radio frequency circuit that have transmitting and receiving functions can be considered as a transceiver module of the terminal device, and the processor that has a processing function can be considered as a processing module of the terminal device. Petition 870250104098, dated 11 / 13 / 2025, pp. 80 / 97 4 / 79

[00352] As shown in FIG. 13, the terminal device includes a processor 1310, a memory 1320 and a transceiver 1330. The processor 1310 may also be called a processing unit, processing board, processing module, processing apparatus or similar, and the transceiver 1330 may also be called a transceiver unit, transceiver apparatus or similar.

[00353] Optionally, a component present in the 1330 transceiver and configured to implement a receiving function may be considered a receiving module, and a component present in the 1330 transceiver and configured to implement a transmitting function may be considered a transmitting module. In other words, the 1330 transceiver includes a receiver and a transmitter. The transceiver may also sometimes be called a transceiver module, transceiver circuit, or similar. The receiver may also sometimes be called a receiver module, receiver circuit, or similar. The transmitter may also sometimes be called a transmitter module, transmitter circuit, or similar.

[00354] For example, in one implementation, processor 1310 is configured to perform a processing action on the terminal device side in modes shown in FIGS. 4 to 8B, and transceiver 1330 is configured to perform receive and send actions on the terminal device side in FIGS. 4 to 8B.

[00355] It should be understood that FIG. 13 is merely an example and not a limitation. The terminal device, including the transceiver module and the processing module, may not depend on the structures shown in FIGS. 9 to 11.

[00356] When the 1300 communication device is the chip, it includes a processor, memory, and a transceiver. The transceiver can be an input / output circuit or a communication interface. The processor can be a processing module, a microprocessor, or an integrated circuit. Petition 870250104098, dated 11 / 13 / 2025, pp. 81 / 97 75 / 79 integrated into the chip. A sending operation performed by the terminal device in the previous method modes can be understood as an output from the chip, and a receiving operation performed by the terminal device in the previous method modes can be understood as an input from the chip.

[00357] This application further provides a chip, including a processor, configured to invoke instructions from memory and execute the instructions stored in memory, so that a communication device in which the chip is installed is enabled to perform the methods in the previous examples.

[00358] This application provides yet another chip, including an input interface, an output interface, and a processor. The input interface, the output interface, and the processor are connected via an internal connection path. The processor is configured to execute code in memory, and when the code is executed, the processor is configured to perform the methods of the previous examples. Optionally, the chip also includes memory, and the memory is configured to store a computer program or code.

[00359] This application further provides a processor, configured to be coupled to a memory and configured to perform a method and a function of the network device or terminal device in any of the preceding embodiments.

[00360] Another embodiment of this application provides a computer program product including instructions. When the computer program product runs on a computer, the method of the previous embodiment is implemented.

[00361] This application also provides a computer program. When the computer program runs on a computer, the method of the previous embodiment is implemented.

[00362] Another embodiment of this application provides a computer-readable storage medium. The computer-readable storage medium stores a computer program. Petition 870250104098, dated 11 / 13 / 2025, pp. 82 / 97 6 / 79 When the computer program is executed by a computer, the method of the previous modality is implemented.

[00363] This application further provides a communication system. The communication system includes a network device 110, a network device 120, and a core network element. Network device 110 is configured to perform the above methods, network device 120 is configured to perform the above methods, and core network element 130 is configured to perform the above methods. For specific descriptions, see the descriptions above. Details are not described again in this document.

[00364] In the descriptions of modalities of this application, unless otherwise indicated, a plurality of means two or more. At least one of the following items (pieces) or a similar expression means any combination of these items, including a single item (piece) or any combination of a plurality of items (pieces). For example, at least one item (piece) of a, b, or c may indicate: a, b, c, aeb, aec, bec, or a, bec, where a, bec may be singular or plural.

[00365] In addition, to clearly describe the technical solutions in the embodiments of this application, terms such as first and second are used in the embodiments of this application to distinguish between the same items or similar items that provide essentially the same functions or purposes. A person skilled in the art may understand that terms such as first and second do not limit a quantity or sequence of execution, and terms such as first and second do not indicate a definite difference. Furthermore, in embodiments of this application, words such as example or for example are used to represent a given example, illustration, or description.

[00366] In the modality descriptions of this request, unless otherwise specified, / represents a relationship between associated objects. For example, A / B can represent A or B. Petition 870250104098, dated 11 / 13 / 2025, pp. 83 / 97 77 / 79 B. In this descriptive report, you describe only one association relationship between associated objects and represent the three possible relationships. For example, A and / or B can represent the following three cases: Only A exists, both A and B exist, and only B exists, where A and B can be singular or plural.

[00367] Sequence numbers from previous processes do not signify execution sequences in the modes of this request. Process execution sequences must be determined based on the functions and internal logic of the processes and should not be interpreted as any limitation on the implementation processes of the modes of this request.

[00368] A person skilled in the art may be aware that, in combination with the examples described in the embodiments disclosed in this descriptive report, algorithm units and steps may be implemented by electronic hardware or a combination of computer software and electronic hardware. Whether the functions are performed by hardware or software depends on the specific applications and design constraints of the technical solutions. A person skilled in the art may use different methods to implement the described functions for each particular application, but it should not be considered that the implementation goes beyond the scope of this application.

[00369] It may be clearly understood by a person skilled in the art that, for the purposes of convenient and brief description, for a detailed working process of the aforementioned system, apparatus and unit, refer to a corresponding process in the aforementioned method modalities. Details are not described again in this document.

[00370] In the various embodiments provided in this application, it should be understood that the system, apparatus and method disclosed may be implemented in other ways. For example, the embodiment of the apparatus described is merely an example. By Petition 870250104098, dated 11 / 13 / 2025, pp. 84 / 97 78 / 79 For example, the division into units is merely a logical function division and may be another division in actual implementation. For example, a plurality of units or components may be combined or integrated into another system, or some features may be skipped or not implemented.

[00371] In addition, the mutual couplings, direct couplings, or communication connections shown or discussed can be implemented through some interfaces. Indirect couplings or communication connections between devices or units can be implemented in electronic, mechanical, or other forms.

[00372] The units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, i.e., they may be located in one position or may be distributed across a plurality of network units. Some or all of the units may be selected based on actual requirements to achieve the objectives of the modality solutions.

[00373] In addition, functional units in the forms of this application may be integrated into a processing unit, or each unit may physically exist alone, or two or more units may be integrated into a unit.

[00374] When functions are implemented in the form of a functional software unit and sold or used as a stand-alone product, the functions may be stored on a computer-readable storage medium. Based on this understanding, the technical solutions of this application essentially, or the part that contributes to conventional technology, or some of the technical solutions, may be implemented in the form of a software product. The computer software product is stored on a storage medium and includes various instructions to instruct a computer device (which may be a personal computer, a server, a network device, Petition 870250104098, dated 11 / 13 / 2025, pp. 85 / 97 79 / 79 or similar) to perform all or some of the steps of the methods in the modalities of this application. The aforementioned storage medium includes any medium that can store program code, for example, a USB flash drive, a removable hard disk, a ROM, a RAM, a magnetic disk or an optical disk.

[00375] Mutual references may be made to the content in different forms of this application. Unless otherwise specified or in the event of a logical conflict, terms and / or descriptions in different forms are consistent and may be mutually referenced, and technical features in different forms may be combined into a new form based on an internal logical relationship between the technical features.

[00376] It may be understood that, in the embodiments of this application, the terminal device, the access network device, or the core network device may perform some or all of the steps in the embodiments of this application. These steps or operations are merely exemplary. In the embodiments of this application, other operations or variations of various operations may additionally be performed. Furthermore, the steps may be performed in a sequence different from a sequence shown in the embodiments of this application, and not all operations in the embodiments of this application may be performed. Petition 870250104098, dated 11 / 13 / 2025, pp. 86 / 97

Claims

1 / 4 CLAIMS 1. A communication method, characterized in that the method is applied to L1 / L2 LTM-enabled mobility, and comprises: obtaining, by a first network device, information about a timing advance TA of a first candidate cell, wherein the first candidate cell belongs to the first network device or to a third network device, and the information about the TA of the first candidate cell is used to determine the use of a random access channel hopping method; and sending, by the first network device, the information about the TA of the first candidate cell to a second network device using a fourth network device.

2. Method according to claim 1, characterized in that obtaining, by the first network device, information about the TA of the first candidate cell comprises: receiving, by the first network device, information about the TA of the first candidate cell from the fourth network device; or receiving, by the first network device, a contention-free random access preamble sent by a terminal device in the first candidate cell; and determining, by the first network device, the information about the TA of the first candidate cell based on the contention-free random access preamble.

3. Method according to claim 2, characterized in that the method further comprises: receiving, by the first network device, request information from the fourth network device, wherein the request information is used to request information about the TA of the first candidate cell.

4. Method, according to any of claims 1 to Petition 870250090255, dated 10 / 03 / 2025, page 22 / 35 2 / 4 3, characterized in that the information about the TA of the first candidate cell comprises at least one of the following: the TA of the first candidate cell; or indicative information indicating that the TA of the first candidate cell is valid; or the remaining validity time of the TA of the first candidate cell; or a time offset of the TA of the first candidate cell, wherein the time offset corresponds to the duration of the TA of the first candidate cell.

5. A method according to any one of claims 1 to 4, characterized in that the first network device is a source distributed unit (DU), the third network device is a candidate DU, the second network device is a target DU, and the fourth network device is a central unit (CU).

6. A method, according to any one of claims 1 to 5, characterized in that the transmission, by the first network device, of information about the TA of the first candidate cell comprises: sending, by the first network device, information about the TA of the first candidate cell to the second network device using the fourth network device and a fifth network device.

7. Communication method, characterized in that the method is applied to L1 / L2 LTM-enabled mobility, and comprises: receiving, by a fourth network device, information about a timing advance, TA, of a first candidate cell from a first network device or a third network device, wherein the first candidate cell belongs to the first network device or the third network device, and the information about the TA of the first candidate cell is used to determine the use of a random access channel hopping method; and sending, by the fourth network device, the information about the TA of the first candidate cell to a second network device.

8. Method according to claim 7, characterized in that the method further comprises: sending, via the fourth network device, request information to the first network device or the third network device, wherein the request information is used to request information about the TA of the first candidate cell.

9. A method according to claim 7 or 8, characterized in that the information about the TA of the first candidate cell comprises at least one of the following: the TA of the first candidate cell; or indicative information indicating that the TA of the first candidate cell is valid; or the remaining validity time of the TA of the first candidate cell; or a time offset of the TA of the first candidate cell, wherein the time offset corresponds to the duration of the TA of the first candidate cell.

10. A method according to any one of claims 7 to 9, characterized in that the first network device is a source distributed unit, DU, the third network device is a candidate DU, the second network device is a target DU, and the fourth network device is a central unit, CU.

11. Method, according to any one of claims 7 to 10, characterized in that the transmission, by the fourth network device, of information about the TA of the first candidate cell comprises: Petition 870250090255, dated 03 / 10 / 2025, page 24 / 35 4 / 4 sending, by the first network device, the information about the TA of the first candidate cell to the second network device using a fifth network device.

12. Communication apparatus, comprising a processor, characterized in that the processor is configured to enable, by executing a computer program or instructions, or by means of a logic circuit, the communication apparatus to perform the method as defined in any one of claims 1 to 6.

13. Communication apparatus, comprising a processor, characterized in that the processor is configured to enable, by executing a computer program or instructions, or by means of a logic circuit, the communication apparatus to perform the method as defined in any one of claims 7 to 11.

14. Computer-readable storage medium, characterized in that the computer-readable storage medium comprises a computer program or instructions, and when the computer program or instructions are run on a computer, the method as defined in any one of claims 1 to 6 is performed.

15. Computer-readable storage medium, characterized in that the computer-readable storage medium comprises a computer program or instructions, and when the computer program or instructions are run on a computer, the method as defined in any one of claims 7 to 11 is performed. Petition 870250090255, dated 10 / 03 / 2025, pp. 25 / 35

Images