Method of communication and communication device

Description

1 / 124 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 switches to any one of several candidate cells. A cell switching decision is made by a distributed unit (DU). In short, the terminal device sends a measurement report of a candidate cell to the DU, and the DU determines, based on the candidate cell's measurement report, the candidate cell as the target cell for a switching and indicates, in a cell switching command, the terminal device's service cell to switch to the target cell.

[0003] Currently, before receiving the cell switching command, the terminal device initiates a random access procedure on each of the candidate cells in order to obtain timing advances (TA) from the plurality of candidate cells. The TA of the candidate cell is used by the terminal device to determine a timing advance for the uplink transmission on the candidate cell. However, in the above method, the terminal device needs to initiate many random access procedures on the plurality of candidate cells, resulting in high power consumption and high random access interference from the terminal device. Therefore, how to reduce the number of random access procedures initiated by the terminal device is an urgent technical problem to be solved. SUMMARY Petition 870250105066, dated 11 / 17 / 2025, page 8 / 146 2 / 124

[0004] This application provides a method of communication and a communication device for reducing the number of random access procedures initiated by a terminal device.

[0005] According to a first aspect, a communication method is provided, including: A terminal device receives a TA from a first candidate cell; and the terminal device receives an identifier of a target cell from a switching and identification information of the first candidate cell, wherein the target cell is a second candidate cell, and the identification information of the first candidate cell indicates the determination of a TA of the target cell based on the TA of the first candidate cell.

[0006] Specifically, the TA of the target cell is determined based on the TA of the first candidate cell.

[0007] Specifically, the terminal device can determine the TA of the second candidate cell based on the TA obtained from the first candidate cell, the target cell identifier, and the identification information of the first candidate cell, and the terminal device does not need to obtain the TA of the second candidate cell by initiating a random access procedure for the second candidate cell. In this way, 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 sends a measurement report of the second candidate cell.

[0009] Specifically, the terminal device reports the measurement report of the second candidate cell, and the measurement report can be used by a network device to determine the second candidate cell as the target cell for switching.

[0010] In a possible implementation, the method also includes: Petition 870250105066, dated 11 / 17 / 2025, page 9 / 146 3 / 124 The terminal device receives indication information, wherein the indication information indicates the sending of a contention-free random access preamble in the first candidate cell, and the contention-free random access preamble is used to determine the TA of the first candidate cell; and the terminal device sends the contention-free random access preamble in the first candidate cell based on the indication information.

[0011] In this way, the terminal device can send the contention-free random access preamble to the first candidate cell based on the indication information. This can improve the efficiency of communication between the terminal device and the network device.

[0012] In one possible implementation, the first candidate cell and the second candidate cell belong to a first network device, and the first candidate cell is different from the second candidate cell.

[0013] Specifically, when the first candidate cell and the second candidate cell are two different candidate cells, the terminal device can initiate a random access procedure for one of the candidate cells in order to determine the TA of the candidate cell, and can determine the TA of the other candidate cell based on the TA of the candidate cell. This can effectively reduce the number of random access procedures that need to be initiated by the terminal device, as well as reduce power consumption and random access interference of the terminal device.

[0014] In a possible implementation, the TA of the first candidate cell and the TA of the target cell are the same.

[0015] In this way, the number of random access procedures that need to be initiated by the terminal device can be effectively reduced, and the power consumption and random access interference of the terminal device can Petition 870250105066, dated 11 / 17 / 2025, page 10 / 146 4 / 124 to be reduced.

[0016] In one possible implementation, the first candidate cell and the second candidate cell belong to a set of candidate target cells for switching.

[0017] According to a second aspect, a communication method is provided, including: A first network device receives a contention-free random access preamble from a first candidate cell; and the first network device sends a target cell identifier of a switching and target cell TA information to a terminal device, wherein the target cell is a second candidate cell, and the target cell TA information is determined based on the contention-free random access preamble of the first candidate cell.

[0018] Specifically, the first network device can determine a TA of the first candidate cell based on the contention-free random access preamble received from the first candidate cell, and can further determine a TA of the second candidate cell based on the TA of the first candidate cell. In this way, when the first network device determines the second candidate cell as the target cell for switching, the first network device does not need to trigger the terminal device to initiate a random access procedure for the second candidate cell. This can effectively reduce the number of random access procedures that need to be initiated by the terminal device and effectively reduce the power consumption and random access interference of the terminal device.

[0019] In a possible implementation, the target cell TA information includes at least one of the following: the target cell TA or identification information of the first candidate cell, wherein the identification information of the first candidate cell indicates the determination of the target cell TA with Petition 870250105066, dated 11 / 17 / 2025, page 11 / 146 5 / 124 based on the first candidate cell.

[0020] Specifically, the terminal device can determine the TA of the second candidate cell based on any of the previous information. In this way, the first network device does not need to trigger the terminal device to initiate the random access procedure for the second candidate cell. Furthermore, the number of random access procedures that need to be initiated by the terminal device can be effectively reduced, and the power consumption and random access interference of the terminal device can be effectively reduced.

[0021] In one possible implementation, the method further includes: The first network device sends indication information to the terminal device, wherein the indication information indicates the sending of the contention-free random access preamble in the first candidate cell; and the indication information includes contention-free random access resource information of the first candidate cell, and the contention-free random access resource information is used for transmission of the contention-free random access preamble.

[0022] In this way, the first network device can instruct the terminal device to send the contention-free random access preamble to the first candidate cell. This helps improve the efficiency of communication between the terminal device and the network device.

[0023] In one possible implementation, the method also includes: The first network device sends configuration information for the first candidate cell and configuration information for the second candidate cell to the terminal device.

[0024] In this way, based on the configuration information of these candidate cells, the terminal device can perform a cell switching and data transmission after the cell switching is complete. Petition 870250105066, dated 11 / 17 / 2025, page 12 / 146 6 / 124

[0025] In one possible implementation, the first candidate cell and the second candidate cell belong to the first network device, and the first candidate cell is different from the second candidate cell.

[0026] Specifically, when the first candidate cell and the second candidate cell are two different candidate cells, the terminal device can initiate a random access procedure for one of the candidate cells in order to determine the TA of the candidate cell, and can determine the TA of the other candidate cell based on the TA of the candidate cell. This can effectively reduce the number of random access procedures that need to be initiated by the terminal device, as well as reduce the power consumption and random access interference of the terminal device.

[0027] In a possible implementation, the TA of the first candidate cell and the TA of the target cell are the same.

[0028] In this way, the number of random access procedures that need to be initiated by the terminal device can be effectively reduced, and the power consumption and random access interference of the terminal device can be reduced.

[0029] In one possible implementation, the first candidate cell and the second candidate cell belong to a set of candidate target cells for switching.

[0030] According to a third aspect, a communication method is provided, including: A first network device receives first indication information from a second network device, wherein the first indication information indicates to determine a TA of a second candidate cell based on a first candidate cell, and the first candidate cell and the second candidate cell belong to a third network device; the first network device receives TA information from the first candidate cell; and the first Petition 870250105066, dated 11 / 17 / 2025, page 13 / 146 7 / 124 The network device sends, based on the TA information of the first candidate cell and the first indication information, an identifier of a target cell for switching and TA information of the target cell to a terminal device, where the target cell is the second candidate cell.

[0031] Specifically, the first network device can determine the relationship between the TA of the first candidate cell and the TA of the second candidate cell based on the first indication information, and the first network device can determine the TA of the second candidate cell based on the first indication information and the TA information obtained from the first candidate cell. In this way, the first network device does not need to trigger the terminal device to initiate a random access procedure for the second candidate cell. Therefore, the number of random access procedures that need to be initiated by the terminal device can be effectively reduced, and the power consumption and random access interference of the terminal device can be reduced.

[0032] In a possible implementation, the target cell TA information includes at least one of the following: the target cell TA or identification information of the first candidate cell, wherein the identification information of the first candidate cell indicates the determination of the target cell TA based on the first candidate cell.

[0033] Specifically, the terminal device can determine the TA of the second candidate cell based on any of the previous information. In this way, the first network device does not need to trigger the terminal device to initiate the random access procedure for the second candidate cell. Furthermore, the number of random access procedures that need to be initiated by the terminal device can be effectively reduced, and power consumption can be lowered. Petition 870250105066, dated 11 / 17 / 2025, page 14 / 146 8 / 124 and the random access interference of the terminal device can be effectively reduced.

[0034] 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 second network device; or the first network device receives TA information from the first candidate cell from the terminal device.

[0035] In this way, in this application, the first network device is supported in obtaining TA information from the first candidate cell in several ways.

[0036] In a possible implementation, the TA information of the first candidate cell includes at least one of the following: the TA of the first candidate cell or the second indication information, wherein the second indication information indicates that at least one of the third network device and the terminal device has the TA of the first candidate cell, and the first candidate cell belongs to the third network device.

[0037] Specifically, based on any of the above information, the first network device can determine not to trigger the terminal device to initiate the random access procedure for the second candidate cell. Furthermore, the number of random access procedures that need to be initiated by the terminal device can be effectively reduced, and the power consumption and random access interference of the terminal device can be effectively reduced.

[0038] In a possible implementation, the first indication information indicates determining the TA of the second candidate cell based on the TA of the first candidate cell; or the first indication information indicates determining the TA of Petition 870250105066, dated 11 / 17 / 2025, page 15 / 146 9 / 124 second candidate cell based on the contention-free random access configuration information of the first candidate cell.

[0039] Specifically, the first network device can determine the TA of the second candidate cell based on a contention-free random access preamble and the TA of the first candidate cell. In this way, the first network device can determine not to trigger the terminal device to initiate the random access procedure for the second candidate cell. Furthermore, the number of random access procedures that need to be initiated by the terminal device can be effectively reduced, and the power consumption and random access interference of the terminal device can be effectively reduced.

[0040] In one possible implementation, the method also includes: The first network device sends third-party indication information to the terminal device, wherein the third-party indication information indicates the sending of the contention-free random access preamble in the first candidate cell, and the contention-free random access preamble is used to determine the TA of the first candidate cell.

[0041] In this way, the first network device can instruct the terminal device to send the contention-free random access preamble to the first candidate cell. This helps improve the efficiency of communication between the terminal device and the first network device.

[0042] In one possible implementation, the method also includes: The first network device receives frequency information from the first candidate cell and frequency information from the second candidate cell that comes from the second network device; and the first network device determines the third indication information based on a frequency from the first candidate cell, a frequency from the second candidate cell and Petition 870250105066, dated 11 / 17 / 2025, page 16 / 146 10 / 124 is a service cell frequency.

[0043] Specifically, the first network device can determine the third indication information based on a frequency of the first candidate cell, a frequency of the second candidate cell, and a frequency of the service cell. This helps the terminal device send a contention-free random access preamble to a candidate cell whose frequency is closest to the frequency of the service cell. Therefore, communication interruption caused by frequency switching performed by the terminal device can be effectively avoided.

[0044] In one possible implementation, the method also includes: The first network device receives subcarrier spacing (SCS) information from the first candidate cell and SCS information from the second candidate cell that is from the second network device; and the first network device determines the third indication information based on an SCS from the first candidate cell, an SCS from the second candidate cell, and an SCS from a service cell.

[0045] Specifically, the first network device can determine the third indication information based on the SCS of the first candidate cell, the SCS of the second candidate cell, and the SCS of the service cell. This helps the terminal device send a contention-free random access preamble to a candidate cell whose SCS is closest to the service cell's SCS. Therefore, communication interruption caused by SCS switching performed by the terminal device can be effectively avoided.

[0046] In one possible implementation, the method also includes: The first network device sends the first request information to the second network device based on a frequency of the first candidate cell, a frequency of the second candidate cell, and a frequency of the service cell, Petition 870250105066, dated 11 / 17 / 2025, page 17 / 146 11 / 124 where the initial request information is used to request the contention-free random access configuration information from the first candidate cell, and the contention-free random access configuration information from the first candidate cell is used for transmitting the contention-free random access preamble.

[0047] Specifically, the first network device can determine, based on a frequency of the first candidate cell, a frequency of the second candidate cell, and a frequency of the service cell, the acquisition of contention-free random access resource information from a specific candidate cell. This helps the terminal device send a contention-free random access preamble to the candidate cell whose frequency is closest to the frequency of the service cell. Therefore, communication interruption caused by frequency switching performed by the terminal device can be effectively avoided.

[0048] In one possible implementation, the method further includes: The first network device sends second request information to the second network device based on the SCS of the first candidate cell, the SCS of the second candidate cell, and the SCS of the service cell, wherein the second request information is used to request the contention-free random access configuration information from the first candidate cell, and the contention-free random access configuration information from the first candidate cell is used for the transmission of the contention-free random access preamble.

[0049] Specifically, the first network device can determine, based on the SCS of the first candidate cell, the SCS of the second candidate cell, and the SCS of the service cell, to obtain contention-free random access configuration information from a specific candidate cell. This helps Petition 870250105066, dated 11 / 17 / 2025, page 18 / 146 12 / 124 the terminal device sends a contention-free random access preamble to the candidate cell whose SCS is closest to the service cell's SCS. Therefore, communication interruption caused by SCS switching performed by the terminal device can be effectively avoided.

[0050] In one possible implementation, the method also includes: The first network device receives contention-free random access resource information from the first candidate cell and contention-free random access configuration information from the second candidate cell that is from the second network device.

[0051] In this way, in this application, the first network device is assisted in the random selection of contention-free random access configuration information. It is understood that the first network device can determine, based on the SCS of the first candidate cell, the SCS of the second candidate cell, and the SCS of the service cell, which contention-free random access configuration information will be selected. This assists the terminal device in sending a contention-free random access preamble to the candidate cell whose SCS is closest to the service cell's SCS. Therefore, communication interruption caused by SCS switching performed by the terminal device can be effectively avoided.Alternatively, the first network device can determine, based on a frequency of the first candidate cell, a frequency of the second candidate cell, and a frequency of the service cell, which contention-free random access configuration information will be selected. This assists the terminal device in sending a contention-free random access preamble to the candidate cell whose frequency is closest to the frequency of the service cell. Therefore, the communication interruption caused by the frequency switching performed by the device is avoided. Petition 870250105066, dated 11 / 17 / 2025, page 19 / 146 13 / 124 terminal can be effectively avoided.

[0052] In a possible implementation, the TA of the first candidate cell and the TA of the target cell are the same.

[0053] In this way, the number of random access procedures that need to be initiated by the terminal device can be effectively reduced, and the power consumption and random access interference of the terminal device can be reduced.

[0054] In one possible implementation, the first candidate cell and the second candidate cell belong to a set of candidate target cells for switching.

[0055] According to a fourth aspect, a communication method is provided, including: A first network device determines the first indication information, wherein the first indication information determines the TA information of a second candidate cell based on a first candidate cell; and the first network device sends the first indication information to a third network device.

[0056] Specifically, the first network device can determine the relationship between a TA of the first candidate cell and a TA of the second candidate cell based on the first indication information, and the first network device can determine the TA of the second candidate cell based on the first indication information and the TA information obtained from the first candidate cell. In this way, the first network device does not need to trigger a terminal device to initiate a random access procedure for the second candidate cell. Therefore, the number of random access procedures that need to be initiated by the terminal device can be effectively reduced, and the power consumption and random access interference of the terminal device can be reduced. Petition 870250105066, dated 11 / 17 / 2025, page 20 / 146 14 / 124

[0057] In one possible implementation, the first network device determines the initial indication information, including: The first network device receives the initial indication information from a second network device.

[0058] In one possible implementation, the method also includes: The first network device receives frequency information from the first candidate cell and frequency information from the second candidate cell that is from the second network device; and the first network device sends the frequency information from the first candidate cell and the frequency information from the second candidate cell to the third network device.

[0059] In one possible implementation, the method also includes: The first network device receives SCS information from the first candidate cell and SCS information from the second candidate cell that is from the second network device; and the first network device sends the SCS information from the first candidate cell and the SCS information from the second candidate cell to the third network device.

[0060] In one possible implementation, the method also includes: The first network device receives the TA information of the first candidate cell from the second network device; and the first network device sends the TA information of the first candidate cell to the third network device.

[0061] In a possible implementation, the TA information of the first candidate cell includes at least one of the following: the TA of the first candidate cell or the second indication information, where the second indication information indicates that the second network device has the TA of the first candidate cell.

[0062] In a possible implementation, the method also includes: Petition 870250105066, dated 11 / 17 / 2025, page 21 / 146 15 / 124 The first network device sends third-party indication information to the second network device, where the third-party indication information indicates the contention-free random access configuration information of the first candidate cell.

[0063] In one possible implementation, the method further includes: The first network device receives request information from the third network device, wherein the request information is used to request the contention-free random access configuration information of the first candidate cell; and the first network device sends the contention-free random access configuration information of the first candidate cell to the third network device.

[0064] In a possible implementation, the TA of the first candidate cell and the TA of the target cell are the same.

[0065] In one possible implementation, the first candidate cell and the second candidate cell belong to a set of candidate target cells for switching.

[0066] According to a fifth aspect, a communication method is provided, including: a first network device determines the first indication information, wherein the first indication information indicates the determination of the TA information of a second candidate cell based on a first candidate cell; and the first network device sends the first indication information to a second network device. In a possible implementation, the method further includes: the first network device sends frequency information of the first candidate cell and frequency information of the second candidate cell to the second network device.

[0067] In a possible implementation, the method also includes: The first network device sends an SCS from the first cell. Petition 870250105066, dated 11 / 17 / 2025, page 22 / 146 16 / 124 candidate and an SCS from the second candidate cell to the second network device.

[0068] In one possible implementation, the method further includes: The first network device receives second indication information from the second network device, where the second indication information indicates to configure contention-free random access configuration information of the first candidate cell; and the first network device sends the contention-free random access configuration information of the first candidate cell to the second network device.

[0069] Optionally, the second indication information may further indicate that contention-free random access configuration information is not configured for candidate cell 2, and contention-free random access configuration information is configured only for candidate cell 1.

[0070] In one 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 contention-free random access configuration information from the first candidate cell.

[0071] In one possible implementation, the method also includes: The first network device sends a TA from the first candidate cell to the second network device.

[0072] In a possible implementation, the TA of the first candidate cell and the TA of a target cell are the same.

[0073] In one possible implementation, the first candidate cell and the second candidate cell belong to a set of candidate target cells for a switching.

[0074] According to a sixth aspect, a communication device is provided, including: a configured transceiver unit Petition 870250105066, dated 11 / 17 / 2025, page 23 / 146 17 / 124 to receive a TA from a first candidate cell. The transceiver unit is configured to receive an identifier from a target cell from a switching operation and identification information from the first candidate cell. The target cell is a second candidate cell, and the identification information from the first candidate cell indicates the determination of a TA from the target cell based on the TA from the first candidate cell.

[0075] In one possible implementation, the transceiver unit is also configured to send a measurement report from the second candidate cell.

[0076] In one possible implementation, the transceiver unit is further configured to receive indication information, wherein the indication information indicates the sending of a contention-free random access preamble in the first candidate cell, and the contention-free random access preamble is used to determine the TA of the first candidate cell. The transceiver unit is configured to send the contention-free random access preamble in the first candidate cell based on the indication information.

[0077] In one possible implementation, the first candidate cell and the second candidate cell belong to the communication device, and the first candidate cell is different from the second candidate cell.

[0078] In a possible implementation, the TA of the first candidate cell and the TA of the target cell are the same.

[0079] In one possible implementation, the first candidate cell and the second candidate cell belong to a set of candidate target cells for switching.

[0080] According to a seventh aspect, a communication apparatus is provided, including: a transceiver unit configured to receive a contention-free random access preamble from a first candidate cell. The transceiver unit is configured to send an identifier of a Petition 870250105066, dated 11 / 17 / 2025, page 24 / 146 18 / 124 target cell of a switching and TA information from the target cell to a terminal device. The target cell is a second candidate cell, and the TA information of the target cell is determined based on the contention-free random access preamble of the first candidate cell.

[0081] In a possible implementation, the target cell TA information includes at least one of the following: a target cell TA or identification information of the first candidate cell, wherein the identification information of the first candidate cell indicates the determination of the target cell TA based on the first candidate cell.

[0082] In one possible implementation, the transceiver unit is further configured to send indication information to the terminal device, wherein the indication information indicates the sending of the contention-free random access preamble in the first candidate cell; and the indication information includes contention-free random access resource information of the first candidate cell, and the contention-free random access resource information is used for transmission of the contention-free random access preamble.

[0083] In one possible implementation, the transceiver unit is further configured to send configuration information for the first candidate cell and configuration information for the second candidate cell to the terminal device.

[0084] In one possible implementation, the first candidate cell and the second candidate cell belong to the communication device, and the first candidate cell is different from the second candidate cell.

[0085] In a possible implementation, the TA of the first candidate cell and the TA of the target cell are the same.

[0086] In one possible implementation, the first candidate cell and the second candidate cell belong to a set of candidate target cells for switching. Petition 870250105066, dated 11 / 17 / 2025, page 25 / 146 19 / 124

[0087] According to an eighth aspect, a communication apparatus is provided, including: a transceiver unit configured to receive first indication information from a second network device, wherein the first indication information indicates the TA determination of a second candidate cell based on a first candidate cell, and the first candidate cell and the second candidate cell belong to a third network device. The transceiver unit is further configured to obtain TA information from the first candidate cell. The transceiver unit is further configured to send, based on the TA information of the first candidate cell and the first indication information, a target cell identifier for a switching and TA information of the target cell to a terminal device, wherein the target cell is the second candidate cell.

[0088] In a possible implementation, the target cell TA information includes at least one of the following: a target cell TA or identification information of the first candidate cell, wherein the identification information of the first candidate cell indicates the determination of the target cell TA based on the first candidate cell.

[0089] In one possible implementation, the transceiver unit is further configured to receive TA information from the first candidate cell of the second network device; or the transceiver unit is further configured to receive TA information from the first candidate cell of the terminal device.

[0090] In a possible implementation, the TA information of the first candidate cell includes at least one of the following: a TA of the first candidate cell or second indication information, wherein the second indication information indicates that at least one of the third network device and the terminal device has the TA of the first candidate cell, and the first candidate cell belongs to the third device of Petition 870250105066, dated 11 / 17 / 2025, page 26 / 146 20 / 124 network.

[0091] In one possible implementation, the first indication information indicates determining the TA of the second candidate cell based on the TA of the first candidate cell; or the first indication information indicates determining the TA of the second candidate cell based on the contention-free random access configuration information of the first candidate cell.

[0092] In one possible implementation, the transceiver unit is further configured to send third indication information to the terminal device, wherein the third indication information indicates the sending of a contention-free random access preamble in the first candidate cell, and the contention-free random access preamble is used to determine the TA of the first candidate cell.

[0093] In one possible implementation, the transceiver unit is further configured to receive frequency information from the first candidate cell and frequency information from the second candidate cell that comes from the second network device. The communication apparatus also includes a processing unit configured to determine the third indication information based on a frequency from the first candidate cell, a frequency from the second candidate cell, and a frequency from a service cell.

[0094] In one possible implementation, the transceiver unit is further configured to receive SCS subcarrier spacing information from the first candidate cell and SCS information from the second candidate cell that comes from the second network device. The communication apparatus also includes a processing unit configured to determine the third indication information based on an SCS from the first candidate cell, an SCS from the second candidate cell, and an SCS from a service cell. Petition 870250105066, dated 11 / 17 / 2025, page 27 / 146 21 / 124

[0095] In one possible implementation, the transceiver unit is further configured to send the first request information to the second network device based on a frequency of the first candidate cell, a frequency of the second candidate cell and a frequency of the service cell, wherein the first request information is used to request the contention-free random access configuration information of the first candidate cell, and the contention-free random access configuration information of the first candidate cell is used for the transmission of the contention-free random access preamble.

[0096] In one possible implementation, the transceiver unit is further configured to send second request information to the second network device based on the SCS of the first candidate cell, the SCS of the second candidate cell, and the SCS of the service cell, wherein the second request information is used to request the contention-free random access configuration information from the first candidate cell, and the contention-free random access configuration information from the first candidate cell is used for transmission of the contention-free random access preamble.

[0097] In one possible implementation, the transceiver unit is further configured to receive contention-free random access configuration information from the first candidate cell and contention-free random access configuration information from the second candidate cell that is from the second network device.

[0098] In a possible implementation, the TA of the first candidate cell and the TA of the target cell are the same.

[0099] In one possible implementation, the first candidate cell and the second candidate cell belong to a set of candidate target cells for switching. Petition 870250105066, dated 11 / 17 / 2025, page 28 / 146 22 / 124

[00100] According to a ninth aspect, a communication apparatus is provided, including: a processing unit, configured to determine the first indication information, wherein the first indication information indicates determining the TA information of a second candidate cell based on a first candidate cell; and a transceiver unit, configured to send the first indication information to a third network device.

[00101] In one possible implementation, the transceiver unit is further configured to receive the first indication information from a second network device.

[00102] In one possible implementation, the transceiver unit is further configured to receive frequency information from the first candidate cell and frequency information from the second candidate cell, which are from the second network device. The transceiver unit is further configured to send the frequency information from the first candidate cell and the frequency information from the second candidate cell to the third network device.

[00103] In one possible implementation, the transceiver unit is further configured to receive SCS information from the first candidate cell and SCS information from the second candidate cell that are from the second network device. The transceiver unit is further configured to send the SCS information from the first candidate cell and the SCS information from the second candidate cell to the third network device.

[00104] In one possible implementation, the transceiver unit is further configured to receive TA information from the first candidate cell of the second network device. The transceiver unit is further configured to send the TA information from the first candidate cell to the third network device.

[00105] In a possible implementation, TA information Petition 870250105066, dated 11 / 17 / 2025, page 29 / 146 23 / 124 of the first candidate cell include at least one of the following: a TA of the first candidate cell or second indication information, where the second indication information indicates that the second network device has the TA of the first candidate cell.

[00106] In one possible implementation, the transceiver unit is further configured to send third-party indication information to the second network device, wherein the third-party indication information indicates the contention-free random access configuration information of the first candidate cell.

[00107] In one possible implementation, the transceiver unit is further configured to receive request information from the third network device, wherein the request information is used to request the contention-free random access configuration information from the first candidate cell. The transceiver unit is further configured to send the contention-free random access configuration information from the first candidate cell to the third network device.

[00108] In a possible implementation, the TA of the first candidate cell and the TA of a target cell are the same.

[00109] In one possible implementation, the first candidate cell and the second candidate cell belong to a set of candidate target cells for a switching.

[00110] According to a tenth aspect, a communication apparatus is provided, including: a processing unit, configured to determine the first indication information, wherein the first indication information indicates determining the TA information of a second candidate cell based on a first candidate cell; and a transceiver unit, configured to send the first indication information to a second network device. Petition 870250105066, dated 11 / 17 / 2025, page 30 / 146 24 / 124

[00111] In one possible implementation, the transceiver unit is further configured to send frequency information from the first candidate cell and frequency information from the second candidate cell to the second network device.

[00112] In one possible implementation, the transceiver unit is further configured to send SCS information from the first candidate cell and SCS information from the second candidate cell to the second network device.

[00113] In one possible implementation, the transceiver unit is further configured to receive second indication information from the second network device, wherein the second indication information indicates the contention-free random access configuration information of the first candidate cell. A first network device sends the contention-free random access configuration information of the first candidate cell to the second network device.

[00114] In one possible implementation, the transceiver unit is further configured to receive request information from the second network device, where the request is used to request contention-free random access configuration information from the first candidate cell.

[00115] In one possible implementation, the transceiver unit is further configured to send a TA from the first candidate cell to the second network device.

[00116] In a possible implementation, the TA of the first candidate cell and the TA of a target cell are the same.

[00117] In one possible implementation, the first candidate cell and the second candidate cell belong to a set of candidate target cells for a switching.

[00118] According to an eleventh aspect, a communication apparatus is provided, including a processor. The processor is configured to: enable, by executing a Petition 870250105066, dated 11 / 17 / 2025, p. 31 / 146 25 / 124 computer program or instructions or by means of a logic circuit, the communication apparatus carrying out the method according to any one of the first aspect and the possible implementations of the first aspect, the communication apparatus carrying out the method according to any one of the second aspect and the possible implementations of the second aspect, the communication apparatus carrying out the method according to any one of the third aspect and the possible implementations of the third aspect, the communication apparatus carrying out the method according to any one of the fourth aspect and the possible implementations of the fourth aspect, or the communication apparatus carrying out the method according to any one of the fifth aspect and the possible implementations of the fifth aspect.

[00119] In one possible implementation, the communication device also includes a memory, configured to store the computer program or instructions.

[00120] In one possible implementation, the communication device also includes a communication interface, configured to input a signal and / or transmit a signal.

[00121] 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 receive a signal and / or transmit a signal. The logic circuit is configured to perform the method according to any 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 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 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 of the fourth aspect and the possible implementations. Petition 870250105066, dated 11 / 17 / 2025, p. 32 / 146 26 / 124 of the fourth aspect. Alternatively, the logic circuit is configured to perform the method according to any of the fifth aspect and the possible implementations of the fifth aspect.

[00122] 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 are run on a computer, the method according to any one of the first aspect and the possible implementations of the first aspect is realized, or the method according to any one of the second aspect and the possible implementations of the second aspect is realized, or the method according to any one of the third aspect and the possible implementations of the third aspect is realized, or the method according to any one of the fourth aspect and the possible implementations of the fourth aspect is realized, or the method according to any one of the fifth aspect and the possible implementations of the fifth aspect is realized.

[00123] According to the fourteenth aspect, a computer program product is provided, including instructions. When the instructions are run on a computer, the method according to any one of the first aspects and the possible implementations of the first aspect is realized, or the method according to any one of the second aspects and the possible implementations of the second aspect is realized, or the method according to any one of the third aspects and the possible implementations of the third aspect is realized, or the method according to any one of the fourth aspects and the possible implementations of the fourth aspect is realized, or the method according to any one of the fifth aspects and the possible implementations of the fifth aspect is realized.

[00124] According to a fifteenth aspect, a chip is provided that includes a logic circuit. The logic circuit is Petition 870250105066, dated 11 / 17 / 2025, p. 33 / 146 27 / 124 is configured to perform the method according to any of the first aspects and the possible implementations of the first aspect. Alternatively, the logic circuit is configured to perform the method according to any of the second aspects and the possible implementations of the second aspect. Alternatively, the logic circuit is configured to perform the method according to any of the third aspects and the possible implementations of the third aspect. Alternatively, the logic circuit is configured to perform the method according to any of the fourth aspects and the possible implementations of the fourth aspect. Alternatively, the logic circuit is configured to perform the method according to any of the fifth aspects and the possible implementations of the fifth aspect.

[00125] 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. The details are not described again in this document. BRIEF DESCRIPTION OF THE DRAWINGS

[00126] Figure 1 is a diagram of a communication system 100 to which one modality of this request is applicable; Figure 2 is a diagram of an application scenario 200 according to one modality of this request; Figure 3 is a diagram of a cell switching procedure; Figure 4 is a schematic flowchart of the interaction of a 400 communication method according to one modality of this request; Figure 5 is a schematic flowchart of the interaction of a 500 communication method according to one modality of this request; Figure 6 is a schematic flowchart of the interaction of a 600 communication method according to one modality of this request; Petition 870250105066, dated 11 / 17 / 2025, page 34 / 146 28 / 124 Figure 7 is a schematic flowchart of the interaction of a communication method 700 according to a modality of this request; Figure 8 is a schematic flowchart of the interaction of an 800 communication method according to one modality of this request; Figure 9 is a schematic flowchart of the interaction of a 900 communication method according to one modality of this request; Figure 10 is a schematic flowchart of the interaction of a communication method 1000 according to one modality of this request; Figure 11 is a schematic flowchart of the interaction of a communication method 1100 according to one modality of this request; Figure 12 is a schematic flowchart of the interaction of a 1200 communication method according to one modality of this request; Figure 13 is a schematic flowchart of the interaction of a 1300 communication method according to one modality of this request; Figure 14 is a schematic flowchart of the interaction of a 1400 communication method according to one modality of this request; Figure 15 is a schematic flowchart of the interaction of a 1500 communication method according to one modality of this request; Figure 16 is a schematic flowchart of the interaction of a 1600 communication method according to one modality of this request; Figure 17 is a diagram of the structure of a 1700 communication device according to one embodiment of this application; Figure 18 is a diagram of the structure of a device. Petition 870250105066, dated 11 / 17 / 2025, page 35 / 146 29 / 124 communication 1800 in accordance with a modality of this request; Figure 19 is a diagram of the structure of a 1900 communication device according to one embodiment of this application; Figure 20 is a diagram of the structure of a 2000 communication apparatus according to an embodiment of this application; and Figure 21 is a diagram of the structure of a 2100 communication device according to an embodiment of this application. DESCRIPTION OF THE MODALITIES

[00127] The following describes technical solutions for this application with reference to the attached drawings.

[00128] The technical solutions in embodiments of this application can be applied to various communication systems, for example, a long-term evolution (LTE) system, an LTE frequency division duplex (FDD) system, an LTE time division duplex (TDD) system, a universal mobile telecommunications system (UMTS), a 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 a high Earth orbit satellite. Petition 870250105066, dated 11 / 17 / 2025, p. 36 / 146 30 / 124

[00129] The technical solutions in the 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 the FDD / TDD system. The technical solutions in the 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 the 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.

[00130] The technical solutions in examples in this application can also be applied to a scenario where 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 examples in this application are also applicable to a dual connectivity (DC) scenario where a terminal is connected to at least two base stations.

[00131] The technical solutions in the modalities of this application may also utilize a macro-micro scenario, including different forms of base stations in a communication network. For example, the base station may be a satellite, a station of Petition 870250105066, dated 11 / 17 / 2025, p. 37 / 146 31 / 124 hot air balloon 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.

[00132] The technical solutions in examples in this application can be applied to a scenario where there is a requirement for high reliability service, for example, a port, industrial manufacturing, transportation, and a coal mine.

[00133] It can also be 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 post-6G wireless communication system. 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.

[00134] 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 device. The terminal device may alternatively be a satellite phone, a mobile phone, a smartphone, a wireless data card, a wireless modem or a machine-type communication device, or it may be a cordless phone, a phone with protocol of Petition 870250105066, dated 11 / 17 / 2025, page 38 / 146 32 / 124 session initiation protocol (SIP), a wireless local loop (WLL) station, a personal digital assistant (PDA), customer-premises equipment (CPE), a 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 autonomous driving (self-driving), a wireless terminal in telemedicine (remote medical), a wireless terminal in a smart grid, a wireless terminal in transportation safety, a wireless terminal in a smart city, a wireless terminal in a smart home, a terminal device in a communication network evolved beyond 5G or similar. This is not limited to the embodiments of this application.

[00135] 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 assist 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 may include a chip and another discrete component. Petition 870250105066, dated 11 / 17 / 2025, page 39 / 146 33 / 124

[00136] 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).

[00137] The network device in embodiments of this application may further include various forms of base stations, for example, a macro base station, a micro base station (also called a small cell), a relay station, a transmission reception point (TRP), a transmission 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.

[00138] The network device in embodiments of this application may alternatively include a network element or a module that implements some base station functions, for example, Petition 870250105066, dated 11 / 17 / 2025, p. 40 / 146 34 / 124 may include one or more of the following: a central unit (CU), a distributed unit (DU), or a radio unit (RU). Optionally, the CU may be further separated into a control plane (CP) of CU and a user plane (UP) of CU. The functions of the CU and DU may be implemented by different network elements or may be implemented by a baseband unit (BBU) of the base station. A function of the RU may be implemented by a radio frequency device of the base station. For example, the radio frequency device of the base station may be a remote radio processing unit (RRU), a pico remote radio unit (pRRU), an active antenna processing 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.

[00139] In embodiments of this application, an apparatus configured to implement a function of the network device may be a network device or an apparatus that may assist 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 may include a chip and another discrete component.

[00140] Figure 1 is a diagram of a communication system 100 to which an embodiment of this application is applicable. As shown in Figure 1, the communication system 100 includes a Petition 870250105066, dated 11 / 17 / 2025, page 41 / 146 35 / 124 network devices 110 and one 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 Figure 1 is merely an example for understanding and cannot limit the scope of protection claimed in this application.

[00141] 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.

[00142] Specifically, network device 110 may use a central unit (central unit, CU) distributed unit (distributed unit, DU) architecture, or it may not use a CU-DU architecture. This is not limited. For ease of description, this request is described using an example where network device 110 uses the CU-DU architecture. Network device 110 may include one CU and at least one DU, and at least one DU communicates with each other via the CU.

[00143] In communication system 100, the DU of network device 110 can perform a cell switching decision. For more details, see Figure 3.

[00144] Figure 2 is a diagram of an application scenario 200 according to an embodiment of this application. As shown in Figure 2, application scenario 200 includes a cell #1 to a cell #3. A terminal device 120 is located in cell #1, and cell #1 is a service cell of terminal device 120. The terminal device receives an RRC reconfiguration message from cell #1, where the RRC reconfiguration message includes L1 / L2 triggered mobility (LTM) candidate cell configurations from cell #2 and cell #3. Cell #2 and cell #3 are candidate cells, and candidate cells are potential target cells for a switch. The terminal device performs the Petition 870250105066, dated 11 / 17 / 2025, page 42 / 146 36 / 124 first LTM switching and second LTM switching based on the same RRC reconfiguration message.

[00145] In summary, before the first LTM switch, cell #1 is the service cell (i.e., an originating service cell), and cells #2 and #3 are candidate cells. After the first LTM switch, the service cell of terminal device 120 switches from cell #1 to cell #2. Cell #2 becomes a service cell of terminal device 120 after the first LTM switch and is also a service cell before the second LTM switch. Cell #1 becomes a candidate cell for the second LTM switch, and cell #3 remains a candidate cell. After the second LTM switch, terminal device 120 switches 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 switch, and cell #1 remains a candidate cell.In other words, each of cells #1 through #3 can become a service cell after the switching is complete. For ease of differentiation and description, in this application, cell #1 is defined as the source service cell (further explanation is provided below), cell #2 is defined as a target cell for the first LTM switching (terminal device 120 switches from cell #1 to cell #2), and cell #3 is merely a candidate cell.

[00146] In application scenario 200, a network device 110 interacting with terminal device 120 is a base station. If network device 110 uses a split CU-DU architecture, network device 110 will include one CU and at least one DU. Cell #1 to cell #3 belong to different DUs of the same CU, and all DUs can belong to network device 110. Alternatively, cell #1 to cell #3 all belong to the same DU, and the DU belongs to network device 110. This Petition 870250105066, dated 11 / 17 / 2025, page 43 / 146 37 / 124 In this way, application scenario 200 can be applied to interaction within the base station. In application scenario 200, cells #1 to #3 can alternatively belong to different DUs of different CUs. For example, cell #1 belongs to DU 1 of CU 1, and cells 2 and #3 belong to DU 2 of CU 2, where CU 1 and CU 2 are different. In this way, application scenario 200 can be applied to interaction between base stations.

[00147] In conclusion, application scenario 200 can be applied to interaction between base stations and interaction within a base station. For ease of description, this request defines a cell as corresponding to a device (referred to as a network device below), and the device can be a DU or a CU. For ease of differentiation, a network device 100 and a network device 400 are defined in this request. 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.

[00148] 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 in this document. Details will not be described again below.

[00149] Figure 3 is a diagram of a procedure of Petition 870250105066, dated 11 / 17 / 2025, page 44 / 146 38 / 124 Cell switching. As shown in Figure 3, the cell switching procedure includes the following steps.

[00150] S310: A terminal device 120 sends measurement report information to a DU 1.

[00151] Correspondingly, DU 1 receives the measurement report information. The measurement report information includes measurement results from a plurality of neighboring cells.

[00152] Optionally, the measurement report information is a layer 3 (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.

[00153] S320: DU 1 sends an uplink radio resource control message transfer (UL RRC message transfer) to a CU.

[00154] Correspondingly, the CU receives the UL RRC message transfer message. The UL RRC message transfer message includes the measurement report information in S310.

[00155] S330: The CU determines to initiate an LTM configuration procedure.

[00156] 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 the candidate LTM cells (which may include cell #1 through cell #3 in Figure 2) based on measurement report information, so that terminal device 120 performs an LTM switch on the candidate LTM cells.

[00157] S340: A CU sends a UE context setup request message. Petition 870250105066, dated 11 / 17 / 2025, pp. 45 / 146 39 / 124 for a DU 2.

[00158] Specifically, the EU context definition 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 cells #1 through #3 in Figure 2. Candidate cell 1 could be cell #2 or cell #3.

[00159] Optionally, at least one candidate cell belongs to the plurality of neighboring cells. The UE context definition request message is used to request LTM configuration information from at least one candidate cell, so that terminal device 120 can perform LTM switching based on the LTM configuration information.

[00160] S350: DU 2 sends an EU context setup response message to CU.

[00161] Specifically, if DU 2 accepts an LTM configuration request, DU 2 determines whether to respond to the UE context definition request message. The UE context definition response message includes lower-layer configuration information (e.g., radio link control (RLC) configuration information, media access control (MAC) configuration information, and physical layer (PHY) configuration information) for at least one candidate cell. This information can be used by terminal device 120 to perform LTM switching and data transmission after LTM switching is complete.

[00162] S360: CU sends a downlink (DL) RRC message transfer message to DU 1.

[00163] Correspondingly, DU 1 receives the message from Petition 870250105066, dated 11 / 17 / 2025, pp. 46 / 146 40 / 124 DL RRC message transfer. The DL RRC message transfer includes an RRC reconfiguration message, and the RRCReconfiguration message includes the lower-layer configuration information for at least one candidate cell.

[00164] S370: DU 1 sends the RRCReconfiguration message to terminal device 120.

[00165] Correspondingly, terminal device 120 receives the RRCReconfiguration message.

[00166] It can be understood that a cell that receives the RRCReconfiguration message is a source service cell, that is, cell #1.

[00167] 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.

[00168] 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. The TA is used to control the uplink transmission time (e.g., via a physical uplink shared channel (PUSCH) or a physical uplink control channel (PUCCH)) from the terminal device, to ensure that reception of uplink transmissions (e.g., via PUSCH or PUCCH) from a plurality of terminal devices on one side of the base station is Petition 870250105066, dated 11 / 17 / 2025, page 47 / 146 41 / 124 synchronized.

[00169] It should be noted that the RRCReconfiguration message can be used for an initial LTM switch (a first LTM switch) and also for a plurality of subsequent switches (e.g., a second LTM switch), without the need for an additional RRCReconfiguration message. Unified descriptions are provided in this document. Details will not be described again below.

[00170] S380: Terminal device 120 sends an RRCReconfigurationComplete message to DU 1.

[00171] Correspondingly, DU 1 receives the message RRCReconfigurationComplete.

[00172] S390: DU 1 sends the message RRCReconfigurationComplete for the CU.

[00173] Correspondingly, the CU receives the message RRCReconfigurationComplete.

[00174] S3100: Terminal device 120 sends a measurement report from candidate cell 1 to DU 1.

[00175] Correspondingly, DU 1 receives the measurement report from candidate cell 1.

[00176] Specifically, 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 on all at least one candidate cell in order to obtain a TA from the candidate cell. The PDCCH order includes contention-free random access configuration information for the candidate cell, and this contention-free random access configuration information is used for the transmission of the contention-free random access preamble. Terminal device 120 sends the contention-free access preambles on all by Petition 870250105066, dated 11 / 17 / 2025, pp. 48 / 146 42 / 124 minus one candidate cell, in order to obtain the TA of the candidate cell. For a TA function, see the descriptions in S370. Details are not described again in this document.

[00177] It can be understood that a PDCCH order corresponds to a candidate cell. 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.

[00178] Optionally, terminal device 120 receives a random access response (RAR) message, in which the random access response message includes the TA of the candidate cell.

[00179] S3110: DU 1 determines candidate cell 1 as a target cell for LTM switching.

[00180] 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 switches to candidate cell 1.

[00181] S3120: DU 1 sends an LTM command to terminal device 120.

[00182] Correspondingly, terminal device 120 receives the LTM command generated by DU 1, where the LTM command includes an identifier of the target cell for switching. Terminal device 120 switches to the target cell based on the LTM command. The target cell is candidate cell 1 (e.g., cell #2).

[00183] Specifically, after receiving the LTM command, terminal device 120 can access the target cell randomly, for example, through a random access channel (RACH), or it can access the target cell in a RACH-less or skip-based manner. Petition 870250105066, dated 11 / 17 / 2025, pp. 49 / 146 43 / 124 random access channel (RACH-skip), for example, by directly accessing the target cell via a PUSCH or PUCCH, without the need to send a random access preamble. The PUSCH or PUCCH needs to carry the indication information a, and the indication information a indicates, to DU 2, that terminal device 120 has successfully accessed candidate cell 1. For example, the indication information a includes a cell-radio network temporary identifier (C-RNTI) of terminal device 120.

[00184] S3130: DU 1 sends an LTM notification to CU.

[00185] Specifically, CU determines the target cell for LTM switching based on the LTM notification. The LTM notification includes the target cell identifier, for example, an identifier for candidate cell 1.

[00186] In addition, the CU sends downlink data to the DU 2 corresponding to the target cell.

[00187] S3140: DU 2 sends an access success message (ACCESS SUCCESS) to CU.

[00188] Correspondingly, the CU receives the access success message, 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.

[00189] It can be understood that, after DU 2 determines, based on the access procedure in S3120, that terminal device 120 successfully accesses the target cell, DU 2 sends the access success message to the CU. Furthermore, the CU determines, based on the target cell identifier in the access success message, that terminal device 120 successfully switches to the target cell.

[00190] Generally, before LTM cell switching is performed, DU 1 indicates to terminal device 120 to separately initiate a random access procedure for the Petition 870250105066, dated 11 / 17 / 2025, page 50 / 146 44 / 124 minus one pre-configured candidate cell, so that DU 1 or DU 2 obtains the TA from at least one candidate cell. After receiving the LTM command, terminal device 120 switches to the target cell based on the LTM command. To obtain the TA from the candidate cell before performing the LTM cell switching, terminal device 120 needs to initiate the random access procedure for each of the at least one candidate cell before receiving the LTM command. If a large number of LTM candidate cells are configured for terminal device 120, it will need to initiate many unnecessary random access procedures, resulting in high power consumption and high random access interference from terminal device 120. Furthermore, communication from terminal device 120 to the service cell may be interrupted.

[00191] 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.

[00192] The communication method and communication apparatus in embodiments of this application are described below with reference to the attached drawings.

[00193] It should be noted that method 400 is described primarily from the DU's point of view, method 500 is described primarily from the point of view of the originating DU, method 600 is described primarily from the point of view of the terminal device, and method 700 is also described primarily from the point of view of the terminal device. Method 400, method 600, and method 700 are related at a technical level or are described primarily from different device viewpoints based on the same technical problem. Related terms and descriptions may be mutually referenced. Method 500, method 600, and method 700 are related at a technical level or are Petition 870250105066, dated 11 / 17 / 2025, page 51 / 146 45 / 124 described primarily from different device viewpoints based on the same technical problem. Related terms and descriptions can be mutually referenced. Therefore, method 400, method 600, and method 700 are associated embodiments; and method 500, method 600, and method 700 are associated embodiments.

[00194] Figure 4 is a schematic flowchart of the interaction of a 400 communication method according to an embodiment of this application. The 400 method can be implemented by a terminal device 120 and a network device 100, or it can be implemented by modules and / or components (e.g., chips or integrated circuits) installed in the terminal device 120 and the network device 100 and having corresponding functions. This is not limited to embodiments of this application. An example is presented below where the 400 method is implemented by the terminal device 120 and the network device 100 for description. For descriptions of the network device 100, see the descriptions in Figure 2. The network device 100 manages a plurality of cells. The plurality of cells includes a candidate cell 1 (e.g., cell #2 in Figure 2) and a candidate cell 2 (e.g., cell #3 in Figure 2). Candidate cell 1 and candidate cell 2 are choanten cells.As shown in Figure 4, method 400 includes the following steps.

[00195] Optionally, in S410a, network device 100 sends configuration information 1 from candidate cell 1 and configuration information 2 from candidate cell 2 to terminal device 120.

[00196] Correspondingly, terminal device 120 receives configuration information 1 from candidate cell 1 and configuration information 2 from candidate cell 2. For specific descriptions of configuration information 1 and 2, see the descriptions of S360 and S370 in Figure 3. Details not Petition 870250105066, dated 11 / 17 / 2025, page 52 / 146 46 / 124 are described again in this document. The configuration information 1 of candidate cell 1 also includes common random access configuration information, and the common configuration information includes a root sequence and the like.

[00197] Thus, based on the configuration information of these candidate cells, terminal device 120 can perform a cell switching and data transmission after the cell exchange is completed.

[00198] Optionally, in S410b, network device 100 sends indication information 1 to terminal device 120, wherein indication information 1 indicates to terminal device 120 to send a contention-free random access preamble 1 on candidate cell 1.

[00199] Specifically, indication information 1 includes contention-free random access configuration information 1 of candidate cell 1, and contention-free random access configuration information 1 is used for transmission of contention-free random access preamble 1. Correspondingly, terminal device 120 receives indication information 1 from network device 100 and can send contention-free random access preamble 1 to candidate cell 1 based on indication information 1. In this way, terminal device 120 can send contention-free random access preamble 1 to candidate cell 1 based on indication information 1. This can improve the efficiency of communication between terminal device 120 and network device 100.

[00200] In addition, terminal device 120 can send the contention-free random access preamble 1 in candidate cell 1 based on the common random access configuration information and the contention-free random access configuration information 1.

[00201] Specifically, the configuration information of Petition 870250105066, dated 11 / 17 / 2025, page 53 / 146 47 / 124 contention-free random access 1 includes information indicating a time-frequency resource used to transmit the contention-free random access preamble 1 in candidate cell 1 and / or an identifier of the contention-free random access preamble 1. There is a correspondence between the time-frequency resource for the contention-free random access preamble 1 and a synchronization signal and physical broadcast channel block (SSB) or a reference signal (RS) for channel state information (CSI). The contention-free random access preamble 1 and / or a time-frequency resource for contention-free random access are used to uniquely identify terminal device 120 in candidate cell 1.

[00202] In one possible implementation, indication information 1 may be the previous PDCCH order. Network device 100 triggers, based on the PDCCH order, terminal device 120 to send the contention-free random preamble 1 in candidate cell 1 to perform TA measurement on the contention-free random access preamble 1, in order to determine a TA of candidate cell 1. Furthermore, network device 100 determines, based on the contention-free random access preamble 1 and / or the time-frequency feature for contention-free random access, that a currently accessed terminal device is terminal device 120.

[00203] S410: Terminal device 120 sends contention-free random access (CFRA) preamble 1 to network device 100 in candidate cell 1.

[00204] Correspondingly, network device 100 receives the contention-free random access preamble 1 on candidate cell 1 and determines the TA of candidate cell 1 and a TA of candidate cell 2 based on the random access preamble. Petition 870250105066, dated 11 / 17 / 2025, page 54 / 146 48 / 124 contention-free 1. The contention-free random access preamble 1 can uniquely identify the terminal device 120 in candidate cell 1.

[00205] Specifically, the same network device (which may be network device 100 in method 400, or network device 300 in the subsequent method 500, without limitation) manages two different cells: cell A and cell B. If cell A and cell B are coantenna cells, it is determined that there is a correlation between a TA of cell A and a TA of cell B. The correlation may be as follows: for the same terminal device, the TA of cell A and the TA of cell B are equal, or an absolute value of a difference between the TA of cell A and the TA of cell B is less than a threshold. The threshold may be defined as a cyclic prefix (CP) length of cell A or cell B, or another value. The previous definition may be even more applicable to the following embodiments. Candidate cell 1 could be cell A, and candidate cell 2 could be cell B. Therefore, there is a correlation between the TA of candidate cell 1 and the TA of candidate cell 2.This description also applies to all of the following modalities. Details will not be described again below.

[00206] Specifically, network device 100 can determine a candidate cell group. The candidate cell group includes coantenna candidate cells, and the TAs of the plurality of candidate cells in the group meet the above correlation. For example, candidate cell 1 and candidate cell 2 belong to the candidate cell group.

[00207] In one possible implementation, candidate cell 1 and candidate cell 2 belong to a set of candidate target cells for an LTM switch. A service cell of terminal device 120 can switch to any candidate cell in the set of candidate target cells for the switch. The set of candidate target cells for the LTM switch can Petition 870250105066, dated 11 / 17 / 2025, page 55 / 146 49 / 124 being the group of candidate cells above.

[00208] In one possible implementation, network device 100 is a DU (which is a DU corresponding to cell #1 to cell #3), and the DU is responsible for managing the service cell, candidate cell 1, and candidate cell 2 of terminal device 120. For ease of understanding, an example is used below in which network device 100 is the DU for description.

[00209] S420: Network device 100 sends a target cell identifier for a switching and target cell TA information to terminal device 120, wherein the target cell is candidate cell 2, and the target cell TA information is determined based on the contention-free random access preamble 1 of candidate cell 1.

[00210] Correspondingly, terminal device 120 receives the target cell identifier for switching and the target cell TA information. Terminal device 120 determines, based on the target cell identification information, candidate cell 2 as the target cell for switching.

[00211] In one possible implementation, the target cell identifier for switching and the target cell TA information are carried in the LTM command message shown in S3120 in Figure 3. The LTM command message can be a media access control (MAC) element and is generated by the DU.

[00212] Optionally, the target cell identifier for switching and the target cell TA information can be carried separately, in the same information, or in different information. This is not limited.

[00213] In one possible implementation, the TA information of the target cell can be determined based on the contention-free random access preamble 1 of candidate cell 1: Network device 100 (the DU) determines that the TA of candidate cell 1 and a TA of the target cell meet the above correlation if Petition 870250105066, dated 11 / 17 / 2025, page 56 / 146 50 / 124 if candidate cell 1 and the target cell are coantenna candidate cells. Therefore, network device 100 (the DU) determines the TA (e.g., a first TA) of candidate cell 1 based on the contention-free random access preamble 1 and subsequently determines the TA (e.g., a second TA) of the target cell based on the correlation between the two TAs. For example, the first TA and the second TA are the same.

[00214] In another possible implementation, the TA information of the target cell is determined based on the contention-free random access preamble 1 of candidate cell 1, which could be: Network device 100 (the DU) determines the TA of the target cell based on the contention-free random access preamble 1 obtained from candidate cell 1 and the previous correlation.

[00215] The target cell TA is determined in the manner described above. By determining candidate cell 2 as the target cell for LTM switching, network device 100 (the DU) does not need to trigger terminal device 120 to initiate a random access procedure to the target cell in order to obtain the target cell TA. In this way, the number of random access procedures initiated by the terminal device can be effectively reduced, and the service cell communication interruption can also be reduced.

[00216] In a possible implementation, the target cell's TA information includes at least one of the following: Target cell TA or candidate cell identification information 1.

[00217] In a P1 example, the target cell's TA is an absolute value of the target cell's TA. Terminal device 120 determines the target cell's absolute TA value as uplink time and accesses the target cell based on the absolute TA value (i.e., in a RACH-skip or RACH-less manner).

[00218] In a P2 example, before determining candidate cell 2 as the target cell, network device 100 (a DU) Petition 870250105066, dated 11 / 17 / 2025, page 57 / 146 Network device 51 / 124 receives the contention-free random access preamble 1 on candidate cell 1, further determines the TA of candidate cell 1, and sends a RAR message to terminal device 120, wherein the RAR message includes the TA (an absolute value of TA) of candidate cell 1. After determining candidate cell 2 as the target cell, network device 100 (the DU) sends the identification information of candidate cell 1 to terminal device 120, wherein the identification information of candidate cell 1 indicates that terminal device 120 should determine the TA of the target cell based on candidate cell 1. For example, the identification information of candidate cell 1 indicates that the TA of the target cell and the TA of candidate cell 1 are the same. In this way, terminal device 120 can access the target cell (i.e., candidate cell 2) based on the determined TA (i.e., in a RACH-skip or RACH-less manner) of the target cell.

[00219] In one possible implementation, the identification information for candidate cell 1 includes an identifier (e.g., a cell index) for candidate cell 1, or includes information about an identification feature of candidate cell 1 (e.g., a dedicated bit for candidate cell 1).

[00220] It should be noted that method 400 can be applied to a scenario where candidate cell 1, candidate cell 2, and the service cell belong to the DU (i.e., network device 100). Method 400 primarily involves interaction between the DU and terminal device 120.

[00221] The following, with reference to other attached drawings, describes a scenario in which candidate cell 1 and candidate cell 2, as well as the service cell, belong separately to different DUs. For example, candidate cell 1 and candidate cell 2 belong to network device 300, and the service cell belongs to network device 100. Petition 870250105066, dated 11 / 17 / 2025, p. 58 / 146 52 / 124

[00222] It should also be noted that for further descriptions of method 400, see the following method 800.

[00223] Figure 5 is a schematic flowchart of the interaction of a 500 communication method according to an embodiment of this application. The 500 method can be implemented by a terminal device 120, a network device 100, and a network device 200, or it can be implemented by modules and / or components (e.g., chips or integrated circuits) installed in the terminal device 120, the network device 100, and the network device 200 and having corresponding functions. This is not limited to embodiments of this application. An example is presented below where the 500 method is implemented by the terminal device 120, the network device 100, and the network device 200 for description. For descriptions of the network device 100 and the network device 200, see the descriptions in Figure 2. The 500 method includes the following steps.

[00224] S510: Network device 200 sends indication information 2 to network device 100, where indication information 2 indicates to determine a TA of a candidate cell 2 based on a candidate cell 1.

[00225] Correspondingly, network device 100 receives indication information 2 and determines, based on indication information 2, that a TA of candidate cell 1 is related to the TA of candidate cell 2 (for details, see previous descriptions of S410).

[00226] In one implementation, network device 200 receives indication information 2 from network device 300 and then sends indication information 2 to network device 100. Candidate cell 1 and candidate cell 2 are co-antenna cells and both belong to network device 300.

[00227] In another implementation, the network device 200 Petition 870250105066, dated 11 / 17 / 2025, page 59 / 146 53 / 124 determines the indication information 2 and sends the indication information to the network device 100.

[00228] In a possible implementation scenario, network device 100 is a source DU (the source DU is a DU corresponding to a service cell), network device 200 is a CU, and network device 300 is a candidate DU (the candidate DU is a DU corresponding to cell #2 and cell #3). For ease of understanding, we present an example below where network device 100 is the source DU, network device 300 is the candidate DU, and network device 200 is the CU for description. The above definition or description may be applicable to all of the following modalities.

[00229] S520: Network device 100 receives TA information from candidate cell 1.

[00230] In an example U1, network device 100 (the source DU) receives TA information for candidate cell 1 from network device 200 (the CU). Specifically, network device 200 (the CU) sends TA information for candidate cell 1, which is from network device 300 (the candidate DU), to network device 100 (the source DU).

[00231] In a U2 example, network device 100 (the source DU) receives TA information for candidate cell 1 from terminal device 120. Specifically, network device 100 (the source DU) instructs terminal device 120 to report TA information for candidate cell 1, and terminal device 120 reports TA information for candidate cell 1 to network device 100 (the source DU) based on the instruct.

[00232] In a possible implementation, the TA information of candidate cell 1 includes at least one of the following: the TA of candidate cell 1 or indication information 3, wherein indication information 3 indicates that the TA of candidate cell 1 has already been obtained or that random access to the TA of Petition 870250105066, dated 11 / 17 / 2025, page 60 / 146 54 / 124 candidate cell 1 was completed.

[00233] Specifically, in one possible implementation, indication message 3 includes an indication field, indicating that at least one of the network devices 300 (the candidate DU) and the terminal device 120 possesses the TA of candidate cell 1, or that a contention-free random access procedure used to obtain the TA of candidate cell 1 has been completed. Similarly, network device 100 (the source DU) determines, based on indication message 3, that at least one of the network devices 300 (the candidate DU) and the terminal device 120 possesses the TA of candidate cell 1, or that the contention-free random access procedure used to obtain the TA of candidate cell 1 has been completed.

[00234] S530: Network device 100 sends a target cell identifier for a switching and target cell TA information to terminal device 120 based on candidate cell TA information 1 and indication information 2, where the target cell is candidate cell 2.

[00235] Specifically, the target cell identifier for switching and the target cell TA information can be carried in the LTM command message in S3120 in Figure 3. For details, see the descriptions of S420. Details are not described again in this document.

[00236] Specifically, terminal device 120 receives the target cell identifier from the switching and the target cell TA information and determines a TA (i.e., an absolute TA value) of the target cell based on the target cell TA information. The target cell TA information includes at least one of the following: the target cell TA or the candidate cell identification information 1. For detailed descriptions of the target cell TA information, see the related descriptions of method 400. Details are not described again in this document. When the target cell TA information is Petition 870250105066, dated 11 / 17 / 2025, page 61 / 146 55 / 124 the absolute TA value, terminal device 120 determines the absolute TA value of the target cell as uplink time and accesses the target cell based on the absolute TA value (i.e., in a RACH-skip or RACH-less manner). When the target cell's TA information is the identification information of candidate cell 1, terminal device 120 can determine the target cell's TA based on candidate cell 1's TA (to be more specific, the target cell's TA and candidate cell 1's TA are the same) and then access the target cell based on the target cell's TA. For descriptions of how to obtain candidate cell 1's TA, see the related descriptions of method 400. Details are not described again in this document.

[00237] According to the above technical solution, network device 100 (the originating DU) can determine, based on information such as indication information 2, TA information of candidate cell 1, and information that candidate cell 2 is the target cell for switching, that terminal device 120 does not need to be triggered to initiate a random access procedure to the target cell during an LTM switch. In this way, the number of random access procedures initiated by the terminal device can be effectively reduced, and the power consumption of the terminal device can also be reduced.

[00238] In a possible implementation, indication information 2 indicates to determine the TA of candidate cell 2 based on candidate cell 1 includes: Indication information 2 indicates to determine the TA of candidate cell 2 based on the TA of candidate cell 1, or indication information 2 indicates to determine the TA of candidate cell 2 based on the contention-free random access configuration information 1 of candidate cell 1.

[00239] In a T1 example, when the indication information Petition 870250105066, dated 11 / 17 / 2025, page 62 / 146 56 / 124 indicates that the TA of candidate cell 2 is determined based on the TA of candidate cell 1; network device 100 (the originating DU) determines the TA of the target cell based on information such as indication information 2, the TA obtained from candidate cell 1, and the information that candidate cell 2 is the target cell for switching. For example, the TA of the target cell and the TA of candidate cell 1 are the same.

[00240] In an example T2, when indication information 2 indicates the determination of the TA of candidate cell 2 based on the contention-free random access configuration information 1 of candidate cell 1, network device 100 (the source DU) determines the TA of the target cell based on indication information 2, the contention-free random access configuration information 1 of candidate cell 1, and the information that candidate cell 2 is the target cell for switching. For example, the TA of the target cell and the TA of candidate cell 1 are the same.

[00241] Network device 100 (the source DU) can obtain contention-free random access configuration information 1 from candidate cell 1 of network device 200 (the CU). For detailed descriptions of the process, see the descriptions in Figure 9. Details are not described again in this document.

[00242] In a possible implementation, method 500 may also include the following steps.

[00243] S510a1: Network device 200 sends frequency information from candidate cell 1 and frequency information from candidate cell 2 to network device 100.

[00244] S510b1: Network device 100 sends indication information 4 to terminal device 120 based on a candidate cell frequency 1, a candidate cell frequency 2, and a service cell frequency, where indication information 4 indicates to terminal device 120 Petition 870250105066, dated 11 / 17 / 2025, page 63 / 146 57 / 124 to send a contention-free random access preamble 1 in candidate cell 1.

[00245] Correspondingly, terminal device 120 receives indication information 4 from network device 100 (the originating DU) and sends contention-free random access preamble 1 to candidate cell 1 based on indication information 4.

[00246] Specifically, the frequency of candidate cell 1 is close to or equal to the frequency of the service cell (for example, a difference between the frequency of candidate cell 1 and the frequency of the service cell satisfies a small frequency threshold). Alternatively, the frequency of candidate cell 2 and the frequency of the service cell are different or have a large difference. Network device 100 (the originating DU) determines, based on this, to trigger terminal device 120 to initiate a random access procedure for candidate cell 1 and sends indication information 4 to terminal device 120.

[00247] Specifically, network device 100 (the originating DU) can determine the indication information 4 based on a candidate cell frequency 1, a candidate cell frequency 2, and a service cell frequency. This helps terminal device 120 to send a contention-free random access preamble to a candidate cell whose frequency is closest to the service cell frequency. Therefore, service cell communication interruption caused by frequency switching performed by the terminal device can be effectively avoided.

[00248] For detailed descriptions of how network device 100 (the source DU) obtains frequency information 1 from candidate cell 1 and frequency information 2 from candidate cell 2 from network device 200 (the CU), see the descriptions in Figure 10. Petition 870250105066, dated 11 / 17 / 2025, page 64 / 146 58 / 124

[00249] In a possible implementation, method 500 may also include the following steps.

[00250] S520a2: Network device 200 sends subcarrier spacing (SCS) information 1 from candidate cell 1 and SCS information 2 from candidate cell 2 to network device 100.

[00251] S520b2: Network device 100 sends indication information 5 to terminal device 120 based on an SCS 1 from candidate cell 1, an SCS 2 from candidate cell 2, and an SCS from service cell, wherein indication information 5 indicates to terminal device 120 to send a contention-free random access preamble 1 in candidate cell 1.

[00252] Correspondingly, terminal device 120 receives indication information 5 from network device 100 (the originating DU) and sends contention-free random access preamble 1 to candidate cell 1 based on indication information 5.

[00253] Specifically, the SCS of candidate cell 1 is close to or equal to the SCS of the service cell (for example, a difference in SCS between the SCS of candidate cell 1 and the SCS of the service cell satisfies a small SCS threshold). Alternatively, the SCS of candidate cell 2 and the SCS of the service cell are different or have a large difference. Network device 100 (the originating DU) determines, based on this, to initiate a random access procedure for candidate cell 1 and sends indication information 5 to terminal device 120.

[00254] Specifically, network device 100 (the originating DU) can determine the indication information 5 based on the SCS of candidate cell 1, the SCS of candidate cell 2, and the SCS of the service cell. This helps terminal device 120 send a contention-free random access preamble to a candidate cell whose SCS is appropriately more Petition 870250105066, dated 11 / 17 / 2025, page 65 / 146 59 / 124 close to the service cell's SCS. Therefore, service cell communication interruption caused by SCS switching performed by the terminal device can be effectively avoided.

[00255] For detailed descriptions of what network device 100 (the source DU) obtains from network device 200 (the CU), the SCS of candidate cell 1 and the SCS of candidate cell 2, see the descriptions in Figure 10.

[00256] In one possible implementation, when network device 100 (the originating DU) receives contention-free random access configuration information 1 from candidate cell 1 and contention-free random access configuration information 2 from candidate cell 2 from network device 200 (the CU), network device 100 (the originating DU) sends indication information 4 to terminal device 120 based on the frequency of candidate cell 1, the frequency of candidate cell 2, and the frequency of the service cell, or network device 100 (the originating DU) sends indication information 5 to terminal device 120 based on the SCS of candidate cell 1, the SCS of candidate cell 2, and the SCS of the service cell.

[00257] In a possible implementation, method 500 may also include the following step.

[00258] S520c: Network device 100 sends request information 1 to network device 200 based on candidate cell frequency 1, candidate cell frequency 2, and service cell frequency, wherein request information 1 is used to request contention-free random access configuration information 1 from candidate cell 1.

[00259] Specifically, when network device 100 (the source DU) does not have the contention-free random access configuration information for candidate cell 1, the device Petition 870250105066, dated 11 / 17 / 2025, page 66 / 146 Network device 100 (the originating DU) determines, based on the frequency of candidate cell 1, the frequency of candidate cell 2, and the frequency of the service cell, the sending of request information 1 to network device 300 (the candidate DU) via network device 200 (the CU). Correspondingly, network device 300 (the candidate DU) determines the contention-free random access configuration information of candidate cell 1 based on request information 1 and sends the contention-free random access configuration information 1 of candidate cell 1 to network device 100 (the originating DU) via network device 200 (the CU). For descriptions of the frequency of candidate cell 1, the frequency of candidate cell 2, and the frequency of the service cell, see the descriptions in S510a1. Details are not described again in this document.

[00260] In a possible implementation, method 500 may also include the following step.

[00261] S520d: Network device 100 sends request information 2 to network device 200 based on candidate cell SCS 1, candidate cell SCS 2, and service cell SCS, wherein request information 2 is used to request contention-free random access configuration information 1.

[00262] Specifically, when network device 100 (the originating DU) does not possess the contention-free random access configuration information of candidate cell 1, network device 100 (the originating DU) determines, based on the SCS of candidate cell 1, the SCS of candidate cell 2, and the SCS of the service cell, to send request information 2 to network device 300 (the candidate DU) via network device 200 (the CU). Correspondingly, network device 300 (the candidate DU) determines the contention-free random access configuration information 1 of candidate cell 1 based Petition 870250105066, dated 11 / 17 / 2025, page 67 / 146 61 / 124 in request information 2 and sends the contention-free random access configuration information 1 from candidate cell 1 to network device 100 (the source DU) via network device 200 (the CU). For descriptions of the candidate cell 1 SCS, candidate cell 2 SCS, and service cell SCS, see the descriptions in S510a2. Details are not described again in this document.

[00263] It can be understood that method 500 is applied to a scenario where both candidate cell 1 and candidate cell 2 belong to the candidate DU and the service cell belongs to the source DU. Method 500 involves interaction between the source DU, terminal device 120, the candidate DU, and the CU.

[00264] It should be noted that method 500 can additionally be applied to a scenario of interaction between base stations. For example, the originating DU and CU belong to base station 1, and the candidate DU belongs to base station 2. For a specific method, see the previous descriptions.

[00265] Figure 6 is a schematic flowchart of the interaction of a communication method 600 according to an embodiment of this application. The method 600 can be implemented by a terminal device 120, a network device 100, and a network device 300, or it can be implemented by modules and / or components (e.g., chips or integrated circuits) installed in the terminal device 120, the network device 100, and the network device 300 and having corresponding functions. This is not limited to embodiments of this application. An example is presented below where the method 600 is implemented by the terminal device 120, the network device 100, and the network device 300 for description. For descriptions of the network device 100 and the network device 300, see the previous descriptions. As shown in Figure 6, the method 600 includes the following steps. Petition 870250105066, dated 11 / 17 / 2025, page 68 / 146 62 / 124

[00266] S610: Terminal device 120 receives a TA from candidate cell 1.

[00267] Specifically, when candidate cell 1 belongs to network device 100 (a DU) (corresponding to method 400), network device 100 (a DU) triggers, according to a PDCCH order (indicating information 6), terminal device 120 to send a contention-free random preamble 1 on candidate cell 1. Furthermore, network device 100 (a DU) performs TA measurement on the contention-free random access preamble 1 to determine the TA of candidate cell 1. Network device 100 (a DU) sends a RAR message to terminal device 120, where the RAR message includes the TA (an absolute TA value) of candidate cell 1.

[00268] Specifically, when candidate cell 1 belongs to network device 300 (a candidate DU) (corresponding to method 500), network device 100 (an originating DU) (corresponding to method 500) triggers, according to a PDCCH order (indicating information 6), terminal device 120 to send a contention-free random preamble 1 to candidate cell 1. Furthermore, network device 300 (the candidate DU) performs TA measurement on the contention-free random access preamble 1 to determine the TA of candidate cell 1. Network device 300 (the candidate DU) sends a RAR message to the terminal device, where the RAR message includes the TA (an absolute TA value) of candidate cell 1.

[00269] According to the previous method, terminal device 120 can obtain the TA from candidate cell 1.

[00270] S620: Network device 100 sends a target cell identifier for a switching and target cell TA information to terminal device 120, where the target cell is candidate cell 2.

[00271] Correspondingly, terminal device 120 Petition 870250105066, dated 11 / 17 / 2025, page 69 / 146 63 / 124 receives the target cell identifier for switching and the target cell TA information from network device 100. For descriptive details of the target cell TA information and a method for obtaining the target cell TA information from network device 100, see the descriptions of method 400 and method 500. Details are not described again in this document.

[00272] Specifically, terminal device 120 can determine a target cell TA based on target cell TA information. When the target cell TA information is the target cell TA (absolute TA value), the target cell TA (absolute TA value) received by the terminal device in S620 and a candidate cell TA (absolute TA value) indicated in the RAR message received in S610 are the same.

[00273] It should be noted that network device 100 in S620 is network device 100 (the DU) in method 400, or network device 100 (the source DU) in method 500.

[00274] In a possible implementation, method 600 may also include the following step.

[00275] S610a: Terminal device 120 sends a measurement report from candidate cell 2 to network device 100.

[00276] Specifically, terminal device 120 can send the measurement report of candidate cell 2 to network device 100. Network device 100 determines, based on the measurement report of candidate cell 2, whether to use candidate cell 2 as the target cell for switching.

[00277] According to the technical solution above, in this application, the network device does not need to trigger the terminal device to initiate a random access procedure to the target cell. In this way, the number of random access procedures that need to be initiated by the terminal device can be reduced.

[00278] It can be understood that method 600 can be applied Petition 870250105066, dated 11 / 17 / 2025, page 70 / 146 64 / 124 applies to a scenario in which both candidate cell 1 and candidate cell 2 belong to the same candidate DU and a service cell belongs to the originating DU, and can also be applied to a scenario in which the candidate cell, candidate cell 1, and the service cell belong to the same DU.

[00279] It should be noted that method 600 can be additionally applied to a base station interaction scenario. For more details, see the previous descriptions. Details are not described again in this document.

[00280] Figure 7 is a schematic flowchart of the interaction of a communication method 700 according to an embodiment of this application. The method 700 can be implemented by a terminal device 120 and a network device 100, or it can be implemented by modules and / or components (e.g., chips or integrated circuits) installed in the terminal device 120 and the network device 100 and having corresponding functions. This is not limited to embodiments of this application. An example is presented below where the method 700 is implemented by the terminal device 120 and the network device 100 for description. For descriptions of the network device 100, see the previous descriptions. As shown in Figure 7, the method 700 includes the following steps.

[00281] S710: Network device 100 sends a target cell identifier for a switch and a TA of the target cell to terminal device 120, where the target cell is a candidate cell 2.

[00282] Correspondingly, terminal device 120 receives the target cell identifier for switching and the target cell TA information from network device 100. For descriptive details of the target cell TA information and a method for obtaining the target cell TA information from network device 100, see the descriptions of method 400 and method 500. Details are not described in this document. Petition 870250105066, dated 11 / 17 / 2025, page 71 / 146 65 / 124 again.

[00283] It should be noted that network device 100 in S710 can be network device 100 (the DU) in method 400, or it can be network device 100 (the source DU) in method 500.

[00284] S720: Terminal device 120 accesses the target cell based on a TA from the target cell.

[00285] According to the technical solution above, in this application, the network device does not need to trigger the terminal device to initiate a random access procedure to the target cell. In this way, the number of random access procedures that need to be initiated by the terminal device can be reduced.

[00286] It should be noted that, in this request, the terminal device does not need to obtain a TA from a candidate cell 1, and terminal device 120 can access the target cell based on the target cell's TA in an LTM command (i.e., in a RACH-skip or RACH-less manner).

[00287] In a possible implementation, method 700 may also include the following step.

[00288] S710a: Terminal device 120 sends a measurement report from candidate cell 2 to network device 100.

[00289] Specifically, terminal device 120 can send the measurement report of candidate cell 2 to network device 100. Network device 100 determines, based on the measurement report of candidate cell 2, whether to use candidate cell 2 as the target cell for switching.

[00290] It can be understood that method 700 can be applied to a scenario in which both candidate cell 1 and candidate cell 2 belong to the same candidate DU and a service cell belongs to the originating DU, and it can also be applied to a scenario in which the candidate cell, candidate cell 1 and the service cell belong to the same DU.

[00291] It should be noted that method 700 can be applied Petition 870250105066, dated 11 / 17 / 2025, page 72 / 146 66 / 124 in addition to a base station interaction scenario. For more details, see the previous descriptions. Details are not described again in this document.

[00292] It should also be noted that method 700 may also include steps that are the same as or correspond to method 400 prior to method 600, for example, receiving configuration information 1 from candidate cell 1.

[00293] The previous methods are described in more detail below with reference to other attached drawings.

[00294] It should be noted that the methods shown in Figures 8 to 10 are additional descriptions of method 400 to method 700. Furthermore, the methods shown in Figures 8 to 10 can also be understood as supplementary descriptions of method 400 to method 700. A DU 1 in Figure 8 could be the previous network device 100. In Figures 9 and 10, a DU 1 could be the previous network device 100, a DU 2 could be the previous network device 300, and a CU could be the previous network device 200.

[00295] Figure 8 is a schematic flowchart of the interaction of an 800 communication method, according to one embodiment of this application. The 800 method can be implemented by a terminal device 120, DU 1 and a CU, or it can be implemented by modules and / or components (e.g., chips or integrated circuits) installed in the terminal device 120, DU 1 and CU and having corresponding functions. This is not limited to embodiments of this application. The following is an example where the 800 method is implemented by the terminal device 120, DU 1 and CU for descriptive purposes. As shown in Figure 8, the 800 method includes the following steps.

[00296] S801: Terminal device 120 sends measurement report information to DU 1.

[00297] S802: DU 1 sends a message transfer from UL RRC to CU. Petition 870250105066, dated 11 / 17 / 2025, p. 73 / 146 67 / 124

[00298] S803: The CU determines to initiate an LTM configuration procedure.

[00299] S804: CU sends a request message to modify the context of the UE to DU 1.

[00300] For descriptions of S810 to S840, see descriptions of S310 to S340. Details are not described again in this document.

[00301] S805: DU 1 sends a context modification response message from UE to CU.

[00302] If DU 1 accepts an LTM configuration request, it will decide whether to respond to the UE context modification request message. The UE context modification response message includes lower-layer configuration information (e.g., RLC configuration information, MAC configuration information, and PHY configuration information) of a candidate cell. This information can be used by terminal device 120 to perform an LTM switch and data transmission after the LTM switch is complete. The UE context modification response message includes contention-free random access configuration information 1.

[00303] It should be noted that each candidate cell can correspond to a UE context modification request message and a UE context modification response message. Therefore, the UE context modification request message in S802 and the UE context modification request message in S805 are used only as general meanings and not as a quantity limitation.

[00304] S806: The CU sends a DL RRC message transfer message to DU 1.

[00305] For descriptions of the S806, see the descriptions for the S360. Details are not described again in this document.

[00306] Optionally, the CU can send the message of Petition 870250105066, dated 11 / 17 / 2025, page 74 / 146 68 / 124 EU context modification request for DU 1. The EU context modification request message includes an RRCReconfiguration message.

[00307] S807: DU 1 sends the RRCReconfiguration message to terminal device 120.

[00308] S808: Terminal device 120 sends an RRCReconfigurationComplete message to DU 1.

[00309] S809: DU 1 sends the message RRCReconfigurationComplete for the CU.

[00310] Optionally, DU 1 can send the EU context modification response message to CU, where the EU context modification response message includes the RRCReconfigurationComplete message.

[00311] For descriptions of S807 to S09, see descriptions of S370 to S390. Details are not described again in this document.

[00312] S8010: DU 1 sends command 1 to terminal device 120.

[00313] Specifically, command 1 is used to instruct terminal device 120 to send a contention-free random access preamble 1 to a candidate cell 1. Command 1 can be a PDCCH order.

[00314] S8011: Terminal device 120 sends contention-free random access preamble 1.

[00315] Specifically, command 1 includes contention-free random access configuration information 1. Terminal device 120 sends the contention-free random access preamble 1 to candidate cell 1 based on contention-free random access configuration information 1. For descriptions of the contention-free random access configuration information, see the S410b descriptions.

[00316] Correspondingly, DU 1 receives the preamble of Petition 870250105066, dated 11 / 17 / 2025, page 75 / 146 69 / 124 random contention-free access 1 on candidate cell 1 and determines a TA of candidate cell 1 based on the receipt time of the random contention-free access preamble 1.

[00317] Optionally, in S8012, DU 1 sends a RAR 1 message to terminal device 120.

[00318] Correspondingly, terminal device 120 receives the RAR 1 message from DU 1. The RAR 1 message includes the TA of candidate cell 1.

[00319] S8013: Terminal device 120 sends a measurement report from a candidate cell 2 to DU 1.

[00320] S8014: DU 1 determines candidate cell 2 as a target cell for a switching operation.

[00321] Specifically, if DU 1 receives the measurement report from candidate cell 2 and determines, based on the measurement report from candidate cell 2, that the channel quality of candidate cell 2 is better than the channel quality of a service cell, DU 1 can designate candidate cell 2 as the target cell for switching.

[00322] S8015: DU 1 sends an LTM 1 command to terminal device 120.

[00323] Correspondingly, terminal device 120 receives the LTM 1 command from DU 1. The LTM 1 command includes an identifier of the target cell for switching and TA information for the target cell. For descriptions of the target cell's TA information, see the descriptions for method 400. Details are not described again in this document.

[00324] S8016: DU 1 sends an LTM notification to CU.

[00325] S8017: DU 1 sends a successful access message to UC.

[00326] For descriptions of S8016 and S8017, see descriptions of S3130 and S3140. Details are not described again in this document. Petition 870250105066, dated 11 / 17 / 2025, p. 76 / 146 70 / 124

[00327] In method 800, both candidate cell 1 and candidate cell 2 belong to DU 1, and the service cell also belongs to DU 1. DU 1 needs to indicate the service cell of terminal device 120 to switch to candidate cell 1 or candidate cell 2. For ease of description, in this embodiment of this application, an example in which the service cell of terminal device 120 switches to candidate cell 2 is used for description, but a scenario in which the service cell of terminal device 120 switches to candidate cell 1 is not limited.

[00328] In conclusion, DU 1, CU, and terminal device 120 perform the previous interaction procedure, such that the service cell of terminal device 120 switches to the target cell, where the target cell is candidate cell 2. Terminal device 120 determines a TA of candidate cell 2 based on a random access procedure for candidate cell 1. Therefore, a random access procedure is prevented from being initiated on candidate cell 2. In this way, the number of random access procedures that need to be initiated by terminal device 120 can be reduced.

[00329] It can be understood that the sequence of execution of the steps in the previous procedure serves only as an example for comprehension purposes, and is not to be used as a final limitation. The previous procedure may also include a step not mentioned. For example, CU instructs DU 1 to release a communication resource from the service cell.

[00330] It should be noted that one message type used in the previous procedure is used only as an example, and no other possible type is limited.

[00331] It should also be noted that method 800 can be used as a further description of method 400.

[00332] Figure 9 is a schematic flowchart of the interaction of a 900 communication method according to a modality. Petition 870250105066, dated 11 / 17 / 2025, page 77 / 146 71 / 124 of this application. Method 900 can be implemented by a terminal device 120, DU 1, DU 2, and the CU, or it can be implemented by modules and / or components (e.g., chips or integrated circuits) installed in terminal device 120, DU 1, DU 2, and the CU and having corresponding functions. This is not limited. The following is an example where method 900 is implemented by terminal device 120, DU 1, DU 2, and the CU for descriptive purposes. As shown in Figure 9, method 900 includes the following steps.

[00333] S901: Terminal device 120 sends measurement report information to DU 1.

[00334] S902: DU 1 sends a message transfer from UL RRC to CU.

[00335] S903: CU determines to initiate an LTM configuration procedure.

[00336] For descriptions of S901 to S903, see descriptions of S310 to S330. Details are not described again in this document.

[00337] S904: CU sends a request message for EU context definition to DU 2.

[00338] Specifically, the EU context definition request message includes an EU context definition request message 1 and an EU context definition request message 2. The EU context definition request message 1 includes an identifier for candidate cell 1, and the EU context definition request message 1 includes an identifier for candidate cell 2.

[00339] The UE 1 context definition request message is used to request that DU 2 provide LTM 1 configuration information for candidate cell 1, and the UE 2 context definition request message is used to request that DU 2 provide LTM configuration information. Petition 870250105066, dated 11 / 17 / 2025, page 78 / 146 72 / 124 for candidate cell 2, so that terminal device 120 can perform an LTM switch based on the LTM configuration information.

[00340] Optionally, the UE 1 context definition request message may also include indication information 7. Indication information 7 indicates or is used to request that DU 2 provide contention-free random access configuration information 1 for candidate cell 1, and contention-free random access configuration information is not requested to be provided for candidate cell 2.

[00341] Optionally, when the UE context definition request message 1 excludes indication information 7, the context definition request message 1 and the context definition request message 2 include trigger information for the initial RACHs for LTM corresponding to the respective candidate cells. The initial RACH trigger information for LTM is used by DU 2 to provide contention-free random access configuration information for the candidate cell. For details, see the descriptions below.

[00342] Optionally, the EU 1 context definition request message may also include a candidate cell 1 group identifier, and the EU 2 context definition request message may also include a candidate cell group identifier corresponding to candidate cell 2. Candidate cell TAs located in candidate cells indicated by the group identifier are correlated. The candidate cell 1 group identifier and the candidate cell 2 group identifier are the same.

[00343] It should be noted that when the CU determines that there is a correlation between a TA of candidate cell 1 and a TA of candidate cell 2, the CU determines the indication information 7 and the Petition 870250105066, dated 11 / 17 / 2025, page 79 / 146 73 / 124 indication information 2. When DU 2 determines that there is a correlation between the TA of candidate cell 1 and the TA of candidate cell 2, DU 2 determines indication information 2.

[00344] S905: DU 2 sends a UE context definition response message to CU.

[00345] Specifically, the EU context definition reply message sent by DU 2 to CU includes an EU context definition reply message 1 and an EU context definition reply message 2. The EU context definition reply message 1 corresponds to the EU context definition request message 1, and the EU context definition reply message 2 corresponds to the EU context definition request message 2.

[00346] In one possible implementation, when the UE 1 context definition request message includes indication information 7, DU 2 determines, based on indication information 7, whether to provide the contention-free random access configuration information 1 of candidate cell 1 in the UE 1 context definition response message. Correspondingly, when the UE 2 context definition request message excludes indication information 7, DU 2 does not provide the contention-free random access configuration information 2 of candidate cell 2 in the UE 2 context definition response message. The UE 1 context definition response message still includes the LTM configuration information 1 of candidate cell 1, and the UE 2 context definition response message includes the LTM configuration information 2 of candidate cell 2.

[00347] In another possible implementation, when the UE 1 context definition request message includes trigger information for an initial RACH to LTM of candidate cell 1, DU 2 determines, based on the trigger information of the initial RACH to LTM of candidate cell 1, whether to provide the information Petition 870250105066, dated 11 / 17 / 2025, pp. 80 / 146 74 / 124 of contention-free random access configuration 1 for candidate cell 1. Correspondingly, the UE 1 context definition response message includes LTM 1 configuration information and the contention-free random access configuration information 1 for candidate cell 1. When the UE 2 context definition request message includes trigger information from an initial RACH for LTM of candidate cell 2, DU 2 determines a TA determination configuration for candidate cell 2 based on the trigger information from the initial RACH for LTM of candidate cell 2 and the configuration information provided by the contention-free random access configuration information of candidate cell 1. For example, the TA determination configuration indicates that the TA of candidate cell 2 is determined based on the TA of candidate cell 1; to be specific, it could be the preceding indication information 2.In other words, the EU 2 context definition request message includes indication information 2.

[00348] Optionally, instead of relying on the initial RACH trigger information for LTM of the candidate cell, DU 2 may determine to provide the contention-free random access configuration information 1 for candidate cell 1 and determine the TA by determining the configuration information of candidate cell 2 based on a requirement of DU 2. Specifically, the UE 1 context definition request message includes the contention-free random access configuration information 1 of candidate cell 1, and the UE 2 context definition request message includes the indication information 2.

[00349] In another implementation, if DU 2 does not receive indication information 7, DU 2 determines to provide contention-free random access configuration information 1 of candidate cell 1 in the response message of Petition 870250105066, dated 11 / 17 / 2025, page 81 / 146 75 / 124 EU context definition 1.

[00350] It should be noted that for logic or a process in which DU 2 determines to set the contention-free random access configuration information 1 for candidate cell 1 and not to set the contention-free random access configuration information 2 for candidate cell 2, refer to the CU descriptions.

[00351] S906: CU sends a request message to modify the context of the UE to DU 1.

[00352] Specifically, the UE context modification request message includes indication information 2, and indication information 2 indicates the determination of the TA of candidate cell 2 based on candidate cell 1. Indication information 2 can be determined by CU or DU 2 and forwarded by CU. This is not limited. The UE context modification request message includes an RRCReconfiguration message.

[00353] Specifically, when the UE 1 context definition request message includes indication information 7, the CU determines and sends indication information 2 to the DU 1. When the UE 1 context definition request message and the UE 2 context definition request message include the initial RACH trigger information for LTM of the respective candidate cells, the DU 2 determines and sends indication information 2 to the CU, and the CU forwards indication information 2 to the DU 1.

[00354] S907: DU 1 sends the RRCReconfiguration message to terminal device 120.

[00355] S908: Terminal device 120 sends an RRCReconfigurationComplete message to DU 1.

[00356] S909: DU 1 sends the message RRCReconfigurationComplete for the CU.

[00357] For descriptions of S907 to S909, please refer to the descriptions. Petition 870250105066, dated 11 / 17 / 2025, page 82 / 146 76 / 124 from S807 to S809. Details are not described again in this document.

[00358] S9010: DU 1 sends command 1 to terminal device 120.

[00359] Specifically, command 1 is used to instruct terminal device 120 to send a contention-free random access preamble 1 to candidate cell 1.

[00360] S9011: Terminal device 120 sends contention-free random access preamble 1.

[00361] Specifically, command 1 includes the contention-free random access configuration information 1. Terminal device 120 sends the contention-free random access preamble 1 to candidate cell 1 based on the contention-free random access configuration information 1. Correspondingly, DU 2 receives the contention-free random access preamble 1 to candidate cell 1.

[00362] Optionally, in S9012, DU 2 sends a RAR 2 message to terminal device 120.

[00363] Correspondingly, terminal device 120 receives the RAR 2 message. The RAR 2 message includes the TA of candidate cell 1.

[00364] Optionally, terminal device 120 can report a TA from a candidate cell #1 to DU 1.

[00365] Optionally, DU 1 can trigger terminal device 120 to report the TA of candidate cell 1.

[00366] S9013: Terminal device 120 sends a measurement report from a candidate cell 2 to DU 1.

[00367] S9014: DU 1 determines candidate cell 2 as a target cell for a switching.

[00368] Specifically, if DU 1 receives the measurement report of candidate cell 2 from terminal device 120 and determines, based on the measurement report of candidate cell 2, that the channel quality of candidate cell 2 is better than Petition 870250105066, dated 11 / 17 / 2025, page 83 / 146 77 / 124 that the channel quality of a service cell, DU 1 can determine candidate cell 2 as the target cell for switching.

[00369] S9015: DU 1 sends an LTM 1 command to terminal device 120.

[00370] Correspondingly, terminal device 120 receives the LTM 1 command. The LTM 1 command includes an identifier for the target cell for switching and target cell TA information. For descriptions of the target cell TA information, see the previous descriptions.

[00371] S9016: DU 1 sends an LTM notification to CU.

[00372] S9017: DU 2 sends a successful access message to UC.

[00373] For descriptions of S9016 and S9017, see descriptions of S3130 and S3140. Details are not described again in this document.

[00374] In method 900, both candidate cell 1 and candidate cell 2 belong to DU 2, and the service cell belongs to DU 1. DU 1 needs to indicate the service cell of terminal device 120 to switch to candidate cell 1 or candidate cell 2. For ease of description, in this embodiment of this application, an example in which the service cell of terminal device 120 switches to candidate cell 2 is used for description, but a scenario in which the service cell of terminal device 120 switches to candidate cell 1 is not limited.

[00375] In conclusion, DU 1, DU 2, CU, and terminal device 120 perform the previous interaction procedure, such that the service cell of terminal device 120 switches to the target cell, where the target cell is candidate cell 2. Terminal device 120 determines the TA of candidate cell 2 based on a random access procedure for candidate cell 1. Therefore, a random access procedure is prevented from being initiated on candidate cell 2. In this way, the Petition 870250105066, dated 11 / 17 / 2025, page 84 / 146 78 / 124 The number of random access procedures that need to be initiated by the terminal device 120 can be reduced.

[00376] It can be understood that the sequence of execution of the steps in the previous procedure serves only as an example for comprehension purposes, and is not to be used as a final limitation. The previous procedure may also include a step not mentioned. For example, CU instructs DU 1 to release a communication resource from the service cell.

[00377] It should be noted that one message type used in the previous procedure is used only as an example, and no other possible type is limited.

[00378] It should also be noted that method 900 can be used as a further description of method 500.

[00379] It should also be noted that method 900 can be applied to a base station interaction scenario. For example, DU 1 and CU belong to base station 1, and DU 2 belongs to base station 2. For a base station interaction method, see the interaction method within the base station. Details are not described again in this document. When method 800 is applied to the base station interaction scenario, the name of the message above can be changed. For example, the UE context definition request message is changed to an HO (transfer) request, and the UE context definition response message is changed to an HO response.

[00380] Figure 10 is a schematic flowchart of the interaction of a communication method 1000 according to one embodiment of this application. The method 1000 can be implemented by a terminal device 120, DU 1, DU 2 and CU, or it can be implemented by modules and / or components (e.g., chips or integrated circuits) installed in the terminal device 120, DU 1, DU 2 and CU and having corresponding functions. This is not limited. An example is presented below where the method Petition 870250105066, dated 11 / 17 / 2025, page 85 / 146 79 / 124 Method 1000 is performed by terminal device 120, DU 1, DU 2, and CU for descriptive purposes. As shown in Figure 10, method 1000 includes the following steps.

[00381] For S1001 to S1005, see descriptions of S901 to S905. Details are not described again in this document.

[00382] It should be noted that a UE 1 context definition response message in S1050 includes frequency 1 information and / or an SCS 1 from a candidate cell 1, and a UE 2 context definition response message includes frequency 2 information and / or SCS 2 information from a candidate cell 2.

[00383] For descriptions of the frequency and / or SCS of the candidate cell, see the descriptions of method 500. The frequency and / or SCS of the candidate cell can be used by DU 1 to determine the triggering of terminal device 120 to initiate a random access procedure for candidate cell 1.

[00384] S1006: CU sends a request message to modify the context of the UE to DU 1.

[00385] Specifically, the EU context modification request message includes indication information 2, frequency information 1 and / or SCS information 1 of candidate cell 1 and frequency information 2 and / or SCS information 2 of candidate cell 2. The EU context modification request message includes an RRCReconfiguration message.

[00386] It should be noted that the UE context modification request message in S1060 may delete contention-free random access configuration information 1 from candidate cell 1 and contention-free random access configuration information 2 from candidate cell 2. Correspondingly, DU 1 requests contention-free random access configuration information 1 from DU 2. Petition 870250105066, dated 11 / 17 / 2025, page 86 / 146 80 / 124 candidate 1 based on attendance information and / or SCS information.

[00387] S1007: DU 1 sends the RRCReconfiguration message to terminal device 120.

[00388] S1008: Terminal device 120 sends an RRCReconfigurationComplete message to DU 1.

[00389] S1009: DU 1 sends the message RRCReconfigurationComplete for the CU.

[00390] For descriptions of S1006 to S1009, see descriptions of S906 to S909. Details are not described again in this document.

[00391] S1010: DU 1 sends command 1 to terminal device 120.

[00392] Specifically, command 1 is used to instruct terminal device 120 to send a contention-free random access preamble 1 on candidate cell 1. For details of S1010, see the frequency information descriptions and / or the SCS information in method 500.

[00393] S1011: Terminal device 120 sends contention-free random access preamble 1.

[00394] For descriptions of the S1011, see the descriptions for the S9011.

[00395] Optionally, in S1012, DU 2 sends a RAR 3 message to terminal device 120.

[00396] For descriptions of the S1012, see the descriptions for the S9012.

[00397] S1013: Terminal device 120 sends a measurement report from candidate cell 2 to DU 1.

[00398] S1014: DU 1 determines candidate cell 2 as a target cell for a switching.

[00399] For descriptions of S1014, see descriptions of S9014.

[00400] S1015: DU 1 sends an LTM 1 command to the Petition 870250105066, dated 11 / 17 / 2025, p. 87 / 146 81 / 124 terminal device 120.

[00401] For descriptions of the S1015, see the descriptions for the S9015.

[00402] S1016: DU 1 sends an LTM notification to CU.

[00403] S1017: DU 2 sends a successful access message to UC.

[00404] For descriptions of S1016 and S1017, see descriptions of S3130 and S3140. Details are not described again in this document.

[00405] In method 1000, both candidate cell 1 and candidate cell 2 belong to DU 2, and a service cell belongs to DU 1. DU 1 needs to indicate the service cell of terminal device 120 to switch to candidate cell 1 or candidate cell 2. For ease of description, in this embodiment of this application, an example in which the service cell of terminal device 120 switches to candidate cell 2 is used for description, but a scenario in which the service cell of terminal device 120 switches to candidate cell 1 is not limited.

[00406] In conclusion, DU 1, DU 2, CU, and terminal device 120 perform the previous interaction procedure, such that terminal device 120 switches from the service cell to the target cell, where the target cell is candidate cell 2. Terminal device 120 determines a TA of candidate cell 2 based on the random access procedure for candidate cell 1. Therefore, a random access procedure is prevented from being initiated on candidate cell 2. In this way, the number of random access procedures that need to be initiated by terminal device 120 can be reduced.

[00407] It may be understood that the sequence of execution of the steps in the previous procedure serves only as an example for comprehension purposes, and is not to be used as a final limitation. The previous procedure may also include a non- Petition 870250105066, dated 11 / 17 / 2025, page 88 / 146 82 / 124 mentioned. For example, CU tells DU 1 to release a service cell communication resource.

[00408] It should be noted that one message type used in the previous procedure is used only as an example, and no other possible type is limited.

[00409] It should also be noted that method 1000 can be used as a further description of method 500.

[00410] It should also be noted that method 1000 can be applied to a base station interaction scenario. For example, DU 1 and CU belong to base station 1, and DU 2 belongs to base station 2. For a base station interaction method, see the interaction method within the base station. Details are not described again in this document. When method 1000 is applied to the base station interaction scenario, the name of the message above can be changed. For example, a UE context definition request message is changed to an HO (transfer) request, and a UE context definition response message is changed to an HO response.

[00411] In embodiments of this application, method 400 to method 1000 can be applied to a switching field of a candidate cell and also to a switching field of a physical cell identifier (PCI). Specifically, a cell can be associated with a plurality of PCIs, and the plurality of PCIs includes a service PCI and a plurality of additional PCIs. For details, see Figure 11.

[00412] Figure 11 is a schematic flowchart of the interaction of a communication method 1100, according to one embodiment of this request. The method 1000 can be implemented by a terminal device 120, a DU 1 and a CU, or it can be implemented by modules and / or components (e.g., chips or integrated circuits) installed in the terminal device 120, in the DU 1 and in the Petition 870250105066, dated 11 / 17 / 2025, p. 89 / 146 83 / 124 CU and which have corresponding functions. This is not limited. An example is presented below where method 1100 is performed by terminal device 120, DU 1, and CU for descriptive purposes. As shown in Figure 11, method 1100 includes the following steps.

[00413] S1101: The CU sends an RRCReconfiguration message to DU 1.

[00414] Correspondingly, DU 1 receives the RRCReconfiguration message from the CU. The RRCReconfiguration message includes configuration information for a plurality of additional PCIs (for example, configuration information for a first additional PCI and configuration information for a second additional PCI, or configuration information for a reference signal (RS)). The plurality of additional PCIs corresponds to the same service PCI. The configuration information for the first additional PCI includes a RACH configuration.

[00415] S1102: DU 1 sends the RRCReconfiguration message to terminal device 120.

[00416] Specifically, terminal device 120 receives the RRCReconfiguration message using a transmission configuration indicator (TCI) state from the service PCI or the first additional PCI.

[00417] S1103: Terminal device 120 sends an RRCReconfigurationComplete message to DU 1.

[00418] S1104: DU 1 sends the message RRCReconfigurationComplete for the CU.

[00419] S1105: DU 1 sends a PDCCH order to terminal device 120.

[00420] Correspondingly, terminal device 120 receives the PDCCH order from DU 1. The PDCCH order is used to trigger a contention-free random access procedure. Petition 870250105066, dated 11 / 17 / 2025, pp. 90 / 146 84 / 124 The PDCCH order includes a preamble and time-frequency resource information for the contention-free random access procedure. For more details, see the previous descriptions of the PDCCH order.

[00421] S1106: Terminal device 120 initiates a contention-free random access preamble to DU 1 based on the PDCCH order and RACH configuration on the first additional PCI.

[00422] Specifically, terminal device 12 sends, to DU 1, based on the PDCCH order and the RACH configuration on the first additional PCI, the contention-free random access preamble used to determine a TA of the first additional PCI. For details of the process description, see the previous descriptions that terminal device 120 sends the contention-free random access preamble to candidate cell 1. The two descriptions are the same. Therefore, the details will not be described again.

[00423] S1107: Terminal device 120 receives a message from RAR 4.

[00424] Specifically, DU 1 determines the TA of the first additional PCI based on the contention-free random access preamble sent by terminal device 120. Correspondingly, DU 1 sends the RAR 4 message, including the TA of the first additional PCI, to terminal device 120. The RAR 4 message includes a first TA command, and the first TA command includes a first absolute TA value. More specifically, the first absolute TA value is an absolute TA value of the first additional PCI.

[00425] S1108: Terminal device 120 sends a lower layer measurement report to DU 1, where the measurement report includes a measurement result of a TCI state from the second additional PCI.

[00426] S1109: DU 1 determines to activate the TCI state of Petition 870250105066, dated 11 / 17 / 2025, pp. 91 / 146 85 / 124 second additional PCI slot.

[00427] Specifically, DU 1 determines, based on the lower layer measurement report reported by terminal device 120, that the channel quality of the second additional PCI is better than the channel quality of the first additional PCI, and DU 1 determines, based on the lower layer measurement report, to enable the TCI state of the second additional PCI and disable the TCI state of the first additional PCI.

[00428] Specifically, the same DU manages two different PCIs: a PCI #1 and a PCI #2. If PCI #1 and PCI #2 are co-antenna PCIs, it is determined that there is a correlation between a TA of PCI #1 and a TA of PCI #2. The correlation can be as follows: for the same terminal device, the TA of PCI #1 and the TA of PCI #2 are the same, or an absolute value of a difference between the TA of PCI #1 and the TA of PCI #2 is less than a threshold. The threshold can be a CP length of PCI #1 or PCI #2, or another value. The first additional PCI can be PCI #1, and the second additional PCI can be PCI #2. Therefore, there is a correlation between the TA of the first additional PCI and the TA of the second additional PCI. Therefore, DU 1 determines the TA of the second additional PCI based on the previous correlation and the contention-free random access preamble that is sent by terminal device 120 and that is used to determine the TA of the first additional PCI.

[00429] S1110: DU 1 sends a second TA command and activation indication information to terminal device 120.

[00430] Specifically, the activation indication information (or TCI status indication for PDCCH) is used to activate the TCI status of the second additional PCI, and the second TA command is used to indicate the TA of the second additional PCI.

[00431] It should be noted that terminal device 120 does not initiate a RACH on the second additional PCI. The second TA command Petition 870250105066, dated 11 / 17 / 2025, page 92 / 146 86 / 124 includes a relative TA of the first TA or an absolute TA. If the second TA command is the absolute TA, the absolute TA and the first TA are equal. If the second TA command is the relative TA, the relative TA is equal to 0, that is, the TA of the second additional PCI and the first TA are equal.

[00432] S1111: Terminal device 120 accesses the second additional PCI in a random access channel hopping manner.

[00433] According to the technical solution above, in this application, a network device does not need to trigger the terminal device to initiate a random access procedure for an additional PCI that needs to be accessed. In this way, the number of random access procedures that need to be initiated by the terminal device can be reduced.

[00434] It is worth noting that for another PCI switching technical solution, please refer to the method above. Details will not be described again in this document.

[00435] It should be noted that method 1100, as well as method 400 and method 800, are similar technical solutions, and the difference between method 1100, method 400 and method 800 lies in the fact that method 1100 is intended for a PCI switching scenario, and method 400 and method 800 are intended for a candidate cell switching scenario. However, the two methods are related or similar in terms of technical solutions. Therefore, the technical solutions or procedural steps described in method 1100 are merely illustrative. The extent of the technical solution and similar solutions can be obtained by reference to the descriptions of method 400 and method 800. This is not limiting.

[00436] Next, we describe in more detail the technical solutions for this request.

[00437] Switching is a very important feature in a 5G system and is triggered primarily by the movement of a Petition 870250105066, dated 11 / 17 / 2025, pp. 93 / 146 87 / 124 terminal device in a connected state of radio resource control (RRC). A basic objective of switching is to switch the terminal device to a neighboring cell with good signal quality before the signal quality of a service cell becomes unavailable for communication, in order to provide continuous and uninterrupted communication service and effectively prevent dropped calls caused by deterioration of the service cell.

[00438] In a 5G RAN architecture, the functions of a base station are divided into two functional units: a distributed unit (DU), responsible for high-performance real-time processing, for example, processing functions in a radio link control (RLC) layer, a media access control (MAC) layer, and a physical layer (PHY), and a central unit (CU), responsible for non-real-time performance processing, for example, layered functions such as a service data convergence protocol (SDCP), SDAP, an RRC layer, or a packet data convergence protocol (PDCP) layer. The CU communicates with the DU via an F1 interface, and the maximum transmission delay is approximately 3 ms to 10 ms.

[00439] In an existing version, a Layer 3 (L3) handover means that a CU receives a measurement result from a terminal device 120, and the measurement result is forwarded to the CU by a DU. The CU determines, based on the measurement result, whether to initiate a handover, for example, if a service cell is faulty. Furthermore, the CU sends a handover command to the DU, which then sends the handover command to the terminal device 120. There are some interactions via an F1 interface and a handover delay. Petition 870250105066, dated 11 / 17 / 2025, pp. 94 / 146 88 / 124

[00440] To reduce transfer delay, the LTM is inserted. A switching decision is delivered from the CU to the DU to reduce the F1 interaction. The DU determines, based on the measurement result from terminal device 120, whether to initiate switching (LTM cell switch). Switching mainly includes intra-DU switching and inter-DU switching. In addition, the DU sends the switching command directly to terminal device 120. Inter-CU switching is also implemented using an existing L3 transfer.

[00441] Currently, an inter-DU LTM procedure and an intra-DU procedure have been introduced, shown in Figure 3. It can be understood that the difference between the intra-DU procedure and the inter-DU LTM procedure, shown in Figure 3, lies in the fact that DU 1 and DU 2 belong to the same body, and there is no interaction between DU 1 and DU 2. For the interaction between CU, DU and UE, see the descriptions in Figure 3.

[00442] When a target gNB-DU detects access to terminal device 120, one solution is random access. More specifically, random access is performed after the LTM, and the target gNB-DU can become aware of the access to terminal device 120. The other solution is channelless random access (RACH-less or RACH-skip), for example, access is performed via a PUSCH or a PUCCH. Specific information may need to be ported to indicate access from a network device and the terminal. An application scenario for this request is primarily the latter solution.

[00443] To allow terminal device 120 to access the target gNB-DU without the need for a random access channel, terminal device 120 needs to obtain a TA before receiving an LTM command. The TA is a command sent by the base station to terminal device 120 to adjust the uplink transmission of terminal device 120. The process may include: terminal device 120 sending an uplink symbol. Petition 870250105066, dated 11 / 17 / 2025, pp. 95 / 146 89 / 124 in advance, according to a command transmitted via PUSCH, PUCCH and an SRS, and the base station sends a Timing Advance Command (TAC) to notify terminal device 120 of the time required for the uplink transmission advance.

[00444] It can be understood that, before receiving the LTM command, terminal device 120 maintains communication with a source cell and performs a random access procedure for at least one candidate cell. Therefore, a network device or terminal device 120 obtains TA information from at least one candidate cell. After receiving the LTM command, where the LTM command indicates a target cell, and the target cell is one of at least one candidate cell, terminal device 120 can perform access based on the pre-obtained TA and through a dedicated PUSCH or PUCCH. Dedicated PUSCH or PUCCH means that the base station indicates a PUSCH or PUCCH resource of terminal device 120 through dedicated signaling.

[00445] Before the LTM command is received, the random access procedure initiated by terminal device 120 is a contention-free random access and mainly includes the following types: First type: 1. Terminal device 120 sends a contention-free random access (CFRA) preamble to a candidate DU. The network device determines a TA based on the CFRA preamble.

[00446] 2. Terminal device 120 receives a RAR from the candidate DU, where the RAR includes a TA command. Terminal device 120 receives the RAR and determines that random access has been completed.

[00447] After random access, a source DU initiates an LTM switch, and the source DU sends an LTM switch command to terminal device 120, where the command of Petition 870250105066, dated 11 / 17 / 2025, pp. 96 / 146 90 / 124 LTM switching does not require carrying the TA command. Second type: 1. Terminal device 120 sends a CFRA preamble to a candidate DU, and the network device determines a TA based on the CFRA preamble.

[00448] 2. Terminal device 120 receives a RAR from the candidate DU from a source DU, where the RAR includes a TA command. The candidate DU sends the RAR to the source DU, and the source DU sends the RAR to terminal device 120. Terminal device 120 receives the RAR and determines that random access has been completed.

[00449] After random access, the originating DU initiates an LTM switch and sends an LTM switch command to terminal device 120, where the LTM switch command does not need to carry the TA command. Third type: 1. Terminal device 120 sends a CFRA preamble to a candidate DU. The candidate DU determines a TA based on the CFRA preamble and sends the TA to a source DU. Terminal device 120 determines that random access has been completed. There is no RAR in this solution.

[00450] After random access, the originating DU determines to initiate an LTM switch, and the originating DU sends an LTM switch command to terminal device 120, where the LTM switch command needs to carry a TA command, and a TA value in the TA command is obtained through CFRA.

[00451] It can be learned that, before receiving the LTM command, terminal device 120 maintains communication with the source cell and initiates random access to at least one candidate cell. As a result, excessive and unnecessary random access is initiated. In some scenarios (for example, in a scenario where the source cell and a candidate target cell are interfrequency cells), a small interruption occurs in Petition 870250105066, dated 11 / 17 / 2025, pp. 97 / 146 91 / 124 source cell.

[00452] Therefore, to reduce unnecessary random access, reduce signaling overhead, and reduce interruptions, this application provides a communication method. In this method, for a plurality of candidate cells, the UE initiates random access once. For example, the plurality of candidate cells send and receive signals through the same transmission and reception point (TRP). Therefore, the TAs of the plurality of candidate cells are the same or can be shared.

[00453] For example, (a) a random access configuration is provided for a candidate cell through negotiation between base stations; and (b) in a scenario where a plurality of random access configurations are provided (different random access configurations correspond to different candidate cells), the originating DU or the candidate DU determines, based on frequency information or BWP information, a candidate cell for which a random access procedure should be initiated.

[00454] For example, in a procedure shown in Figure 12, in an intra-DU scenario, a candidate cell (which may be candidate cell #1 below) managed by a DU 1 has an LTM CFRA resource, and no LTM CFRA resource is allocated to another candidate cell (for example, candidate cell #2). A TA indicated by an LTM command and a TA of candidate cell #1 are the same when a source cell switches to candidate cell #2. Figure 12 includes the following steps.

[00455] For S1201 to S1209, refer to the steps corresponding to Figure 3 and Figure 8.

[00456] It should be noted that, in S1205, both candidate cell #1 and candidate cell #2 are cells of DU 1, a configuration of candidate cell #1 includes a contention-free random access configuration, and candidate cell #2 may exclude a contention-free random access configuration. Petition 870250105066, dated 11 / 17 / 2025, pp. 98 / 146 92 / 124 contention. A contention-free LTM random access configuration includes an LTM contention-free random access preamble and / or an LTM contention-free random access time-frequency feature. A 120 terminal device can be uniquely identified using the preamble and / or the time-frequency feature. Optionally, the LTM contention-free random access configuration includes an SSB or a CSI-RS corresponding to the preamble or the time-frequency feature.

[00457] S1210a: DU 1 sends a PDCCH order to terminal device 120 based on a CFRA configuration of candidate cell #1, where the PDCCH order instructs terminal device 120 to send contention-free random access to a first candidate cell.

[00458] The PDCCH order includes LTM content-free preamble indication information and time-frequency feature indication information.

[00459] S1210b: Terminal device 120 sends, in candidate cell #1, the contention-free random access preamble to DU 1 based on the PDCCH order.

[00460] DU 1 determines a TA of candidate cell #1 based on the contention-free random access preamble and subsequently determines a TA of candidate cell #2. For example, since a transmit antenna and a receive antenna are the same, DU 1 determines that the TA of candidate cell #1 and / or the TA of candidate cell #2 are the same, i.e., the TA values ​​are the same.

[00461] S1210c: DU 1 sends a RAR to terminal device 120, where the RAR carries the TA (an absolute TA value) of candidate cell #1.

[00462] Step 1210c is optional and may not be performed.

[00463] S1210: Terminal device 120 sends a measurement report from candidate cell #2 to DU 1, in which the report Petition 870250105066, dated 11 / 17 / 2025, pp. 99 / 146 Measurement 93 / 124 includes a reference signal received power (RSRP) from candidate cell #2.

[00464] S1211: DU 1 determines candidate cell #2 as a target cell for a switch, where candidate cell #2 is a different cell from candidate cell #1.

[00465] S1212: DU 1 sends an LTM command to terminal device 120, where the LTM command is used to instruct switching to the target cell. For example, a switching command includes a target cell identifier, and the target cell identifier is a candidate cell identifier #2 (e.g., a cell index).

[00466] In one example, the switching command also includes the TA of candidate cell #2. Alternatively, the switching command includes indication information that indicates the determination of the TA of candidate cell #2 based on the TA of candidate cell #1, and the indication information may be, for example, an identifier of candidate cell #1.

[00467] For S1213 and S1214, refer to the steps corresponding to Figure 3 and Figure 8.

[00468] For example, in a procedure shown in Figure 13, in a scenario between DUs, a CU determines a candidate cell (e.g., candidate cell #1) for which an LTM CFRA configuration needs to be provided and a candidate cell (e.g., including candidate cell #2) for which an LTM CFRA configuration is not provided. The CU sends an indication of required LTM CFRA to a candidate DU, so that the DU becomes aware of a candidate cell for which a CFRA configuration needs to be provided. Figure 13 includes the following steps.

[00469] In one example, the CU determines a group of cells for TA acquisition. The group of cells includes a candidate cell with an LTM CFRA configuration and also includes a cell without an LTM CFRA configuration. The CU sends this to a DU. Petition 870250105066, dated 11 / 17 / 2025, pp. 100 / 146 94 / 124 origin, information indicating that the candidate cells belong to the same cell group. The origin DU also determines, based on a TA of the candidate cell with the CFRA configuration, a TA of the candidate cell without the CFRA configuration. Figure 13 includes the following steps.

[00470] For S1301 to S1303, refer to the steps corresponding to Figure 3 and Figure 9.

[00471] S1304: The CU determines that an LTM CFRA configuration is provided for candidate cell #1 and sends a first UE context definition request to the candidate DU, where the request includes an identifier for candidate cell #1 and an indication of required LTM CFRA.

[00472] The CU determines that an LTM CFRA configuration is not provided for candidate cell #2 and sends a second UE context definition request to the candidate DU, where the request includes an identifier for candidate cell #2, but omits a required LTM CFRA indication.

[00473] S1305: The candidate DU sends a candidate cell #1 configuration to the CU in an initial UE context definition response. The candidate cell #1 configuration includes an LTM CFRA configuration (a DU configuration) of a terminal device 120 and may also include an LTM cell configuration (or an LTM cell group configuration) (a UE configuration) of the terminal device 120. The LTM cell configuration may include, for example, RLC configuration information, MAC configuration information, and PHY configuration information. Based on the LTM cell configuration, the terminal device 120 may perform an LTM switch to a corresponding cell and transmit data after the LTM switch. The LTM cell group configuration may include, for example, RLC configuration information, MAC configuration information, and PHY configuration information based on the cell group. Petition 870250105066, dated 11 / 17 / 2025, pp. 101 / 146 95 / 124 Based on the LTM cell configuration, the 12 0 terminal device can perform an LTM switch to a cell within a group of cells and transmit data after the LTM switch.

[00474] The DU configuration indicates that the configuration information is ultimately provided to or can be read from the originating DU. The UE configuration indicates that the configuration is provided to or can be read from terminal device 120.

[00475] The candidate DU can provide the CFRA configuration of the corresponding candidate cell based on the required CFRA indication. In a second UE context definition response, the candidate DU sends a configuration of candidate cell #2 to the CU. The configuration of candidate cell #2 excludes a CFRA configuration (a DU configuration), but may include a configuration of an LTM cell (or a configuration of a group of LTM cells) (a UE configuration). In other words, the candidate DU does not provide a CFRA resource corresponding to a candidate cell without a required CFRA indication.

[00476] S1306: The CU sends a request to modify the UE context to the originating DU.

[00477] The request may include the configuration (UE configuration) of candidate cell #1, the configuration (UE configuration) of candidate cell #2, the LTM CFRA configuration (DU configuration) of candidate cell #1 of the terminal device (the configuration may be included in the candidate cell #1 configuration), and indication information. The indication information indicates the determination of a TA of candidate cell #2 based on candidate cell #1.

[00478] For example, possible indication information indicates that candidate cell #1 and candidate cell #2 belong to the same TA cell group (in a cell group, the originating DU can determine that the TAs of candidate cell #1 Petition 870250105066, dated 11 / 17 / 2025, pp. 102 / 146 96 / 124 and candidate cell #2 are the same). Alternatively, a plurality of candidate cell identifiers can be carried, for example, the identifier of candidate cell #1 and an identifier of a target cell. The target cell identifier is the identifier of candidate cell #2.

[00479] For S1307 to S1309, refer to the corresponding steps in Figure 3.

[00480] S1310-a-1: The originating DU determines, based on the LTM CFRA configuration of candidate cell #1, to trigger a PDCCH command, to instruct terminal device 120 to send an LTM CFRA preamble to candidate cell #1.

[00481] The PDCCH order includes LTM contention-free random access preamble indication information and time-frequency resource indication information.

[00482] S1310-a-2: Terminal device 120 sends the contention-free random access preamble to the candidate DU in candidate cell #1 based on the PDCCH order.

[00483] The candidate DU determines the TA of candidate cell #1 based on the contention-free random access preamble.

[00484] In S1310-a-3-1 and S1310-a-3-2, the candidate DU sends the TA of candidate cell #1 to the originating DU, and the CU can forward the TA of candidate cell #1 to the originating DU.

[00485] The originating DU determines the TA of candidate cell #2 based on the indication information and the TA of candidate cell #1. The TA of candidate cell #2 and the TA of candidate cell #1 are the same, that is, the TA values ​​are the same.

[00486] S1310-a-3: The candidate DU sends a RAR to terminal device 120, where the RAR carries the TA (e.g., an absolute TA value) of candidate cell #1.

[00487] It should be noted that after S1310-a-2, S1310-a-3-1 and S1310-a-3-2 can be performed, or S1310-a-3 can be performed.

[00488] S1310: Terminal device 120 sends a report Petition 870250105066, dated 11 / 17 / 2025, pp. 103 / 146 97 / 124 measurement of candidate cell #2 for the originating DU, where the measurement report includes an RSRP of candidate cell #2.

[00489] S1311: The originating DU determines candidate cell 2 as the target cell for a switching operation.

[00490] S1312: The originating DU sends an LTM command to terminal device 120, where the command includes the identifier of candidate cell #2 (a cell index) and may optionally include TA indication information (e.g., TA information).

[00491] TA indication information may include a solution 1 and a TA value (the TA value and the TA value of candidate cell #1 are the same), or a solution 2 and the identifier of candidate cell #1 (for example, the identifier of candidate cell #1 indicates that the TA of candidate cell #2 is determined based on the TA of candidate cell #1, a network device considers that the TA values ​​of the two cells are the same, and furthermore, terminal device 120 also knows that the TA values ​​of the two cells are the same).

[00492] Solution 1 is applicable to a scenario where S1310-a3-1 and S1310-a-3-2 are performed, and solution 2 is applicable to a scenario where S1310-a-3 is performed. The TA of candidate cell #2 and the TA of candidate cell #1 are the same.

[00493] For S1313 and S1314, refer to the steps corresponding to Figure 3 and Figure 9.

[00494] For example, in a procedure shown in Figure 14, in an inter-DU scenario, a candidate DU determines a candidate cell (e.g., candidate cell #1) for which an LTM CFRA configuration needs to be provided. In a configuration of another candidate cell (e.g., including candidate cell #2), it is indicated that the candidate cell and candidate cell #1 are associated with a TA. For example, the TA values ​​may be the same, or the same TA value may be the same. Petition 870250105066, dated 11 / 17 / 2025, pp. 104 / 146 98 / 124 to be shared.

[00495] In one example, the candidate DU determines a group of cells for TA acquisition. The group of cells includes a candidate cell with an LTM CFRA configuration and also includes a cell without an LTM CFRA configuration. The candidate DU sends information to a source DU indicating that the candidate cells belong to the same group of cells. The source DU then determines, based on a TA of the candidate cell with the CFRA configuration, a TA of the candidate cell without the LTM CFRA configuration. Figure 14 includes the following steps.

[00496] For S1401 to S1403, refer to the steps corresponding to Figure 3 and Figure 9.

[00497] S1404: A CU sends a candidate cell #1 definition request or a candidate cell #2 definition request to the candidate DU.

[00498] Optionally, a request to define each cell may include trigger information for a respective initial RACH for LTM.

[00499] S1405: The candidate DU includes a configuration of the respective candidate cell in a candidate cell #1 UE context definition response message or a candidate cell #2 UE context definition response message.

[00500] For example, the configuration of candidate cell #1 includes a UE configuration and a DU configuration, and the configuration of candidate cell #2 includes a UE configuration and a DU configuration. The UE configurations of candidate cell #1 and candidate cell #2 each include an LTM cell configuration (or an LTM cell group configuration), the DU configuration of candidate cell #1 includes an LTM CFRA configuration of candidate cell #1, and the DU configuration of candidate cell #2 includes a TA determination configuration of candidate cell #2. Petition 870250105066, dated 11 / 17 / 2025, pp. 105 / 146 99 / 124

[00501] Specifically, for the DU configuration of candidate cell #1, the candidate DU can determine, based on the trigger information of an initial RACH for LTM of candidate cell #1, provide the LTM CFRA configuration for candidate cell #1 and determine the TA determination configuration of candidate cell #2 based on the trigger information of an initial RACH for LTM of candidate cell #2 and the LTM CFRA configuration of candidate cell #1. For example, the determination configuration indicates that a TA of candidate cell #2 can be determined based on a TA of candidate cell #1 (the TAs of candidate cell #1 and candidate cell #2 are the same).

[00502] In another example, the candidate DU may not determine a configuration based on the trigger information of the respective candidate cell, but determine the LTM CFRA configuration and the TA determination configuration based on a requirement of the candidate DU. Specifically, the DU configuration of candidate cell #2 includes initial indication information. The initial indication information indicates the determination of the TA of candidate cell #2 based on the TA of candidate cell #1, for example, it indicates that the TAs of candidate cell #1 and candidate cell #2 may be the same or belong to the same group of candidate TA cells, or that the DU configuration of candidate cell #2 includes an LTM CFRA configuration identifier equal to that of candidate cell #1.

[00503] S1406: CU sends the configuration of candidate cell #1 (including CFRA configuration) and the configuration of candidate cell #2 (excluding CFRA and optionally including the first indication information) to the candidate DU.

[00504] For S1407 to S1409, refer to the steps corresponding to Figure 3 and Figure 9.

[00505] S1410-a-1: The originating DU determines, based on the CFRA LTM ​​configuration of candidate cell #1, to fire a Petition 870250105066, dated 11 / 17 / 2025, pp. 106 / 146 100 / 124 PDCCH order, to instruct the terminal device to send an LTM CFRA preamble to candidate cell #1.

[00506] The PDCCH order includes LTM contention-free random access preamble indication information and time-frequency resource indication information.

[00507] S1410-a-2: Terminal device 120 sends the contention-free random access preamble to the candidate DU in candidate cell #1 based on the PDCCH order.

[00508] The candidate DU determines the TA of candidate cell #1 based on the contention-free random access preamble.

[00509] In S1410-a-3-1 and S1410-a-3-2, the candidate DU sends the TA of candidate cell #1 to the originating DU, and the CU can forward the TA of candidate cell #1 to the originating DU.

[00510] The originating DU determines the TA of candidate cell #2 based on the indication information and the TA of candidate cell #1. The TA of candidate cell #2 and the TA of candidate cell #1 are the same, that is, the TA values ​​are the same.

[00511] S1410-a-3: The candidate DU sends a RAR to terminal device 120, where the RAR carries the TA (e.g., an absolute TA value) of candidate cell #1.

[00512] After S1410-a-2, S1410-a-3-1 and S1410-a-3-2 can be performed, or S1410-a-3 can be performed.

[00513] S1410: Terminal device 120 sends a measurement report of candidate cell #2 to the originating DU, in which the measurement report includes an RSRP of candidate cell #2.

[00514] S1411: The originating DU determines candidate cell 2 as a target cell for a switching operation.

[00515] S1412: The originating DU sends an LTM command to terminal device 120, where the command includes an identifier for candidate cell #2 (a cell index) and may optionally include TA indication information (e.g., TA information).

[00516] TA indication information may include a Petition 870250105066, dated 11 / 17 / 2025, pp. 107 / 146 101 / 124 solution 1 and a TA value (the TA value and the TA value of candidate cell #1 are the same), or a solution 2 and an identifier of candidate cell #1 (for example, the identifier of candidate cell #1 indicates that the TA of candidate cell #2 is determined based on the TA of candidate cell #1, a network device considers that the TA values ​​of the two cells are the same, and furthermore, the terminal device 120 also knows that the TA values ​​of the two cells are the same).

[00517] Solution 1 is applicable to a scenario where S1410-a3-1 and S1410-a-3-2 are performed, and solution 2 is applicable to a scenario where S1410-a-3 is performed. The TA of candidate cell #2 and the TA of candidate cell #1 are the same.

[00518] For S1413 and S1414, refer to the steps corresponding to Figure 3 and Figure 9.

[00519] For example, in a procedure shown in Figure 15, in a scenario between DUs, an originating DU requests a CFRA feature from a candidate cell #1 of a candidate DU based on indication information (indicating the determination of a TA of a candidate cell #2 based on candidate cell #1) about a way to determine the TA of candidate cell #2. For a way in which the originating DU obtains the indication information, see the descriptions in Figures 12 to 14. Figure 15 includes the following steps.

[00520] For S1501 to S1504, refer to the steps corresponding to Figure 3 and Figure 10.

[00521] S1505: The candidate DU decides not to provide a CFRA configuration for candidate cell #1 and not to provide a CFRA configuration for candidate cell #2.

[00522] An EU context definition response message from candidate cell #1 does not contain the LTM CFRA configuration from candidate cell #1, and an EU context definition response message from candidate cell #2 does not contain the Petition 870250105066, dated 11 / 17 / 2025, pp. 108 / 146 102 / 124 LTM CFRA configuration of candidate cell #2. However, the response message from candidate cell #1 or candidate cell #2 includes initial indication information, where initial indication information is information indicating that the TAs of a terminal device in candidate cell #1 and candidate cell #2 may be the same.

[00523] The response message from candidate cell #1 and the response message from candidate cell #2 may also include secondary indication information, wherein the secondary indication information is used for frequency information (e.g., BWP information) corresponding to a random access setting of candidate cell #1 and / or a random access setting of candidate cell #2.

[00524] It can be understood that the UE context definition response message from candidate cell #1 includes a configuration from candidate cell #1, but the configuration includes a configuration from an LTM cell and excludes the LTM CFRA configuration; and the UE context definition response message from candidate cell #2 includes a configuration from candidate cell #2, but the configuration includes a configuration from an LTM cell and excludes the LTM CFRA configuration.

[00525] S1506: A CU sends an RRC reconfiguration to the originating DU, where the RRC reconfiguration includes the settings (UE settings) of candidate cell #1 and candidate cell #2 and the first indication information.

[00526] Optionally, the RRC reconfiguration may also include the second indication information for candidate cell #1 and candidate cell #2.

[00527] For S1507 to S1509, refer to the steps corresponding to Figure 3 and Figure 10.

[00528] S1510-a: The originating DU determines, based on the initial nomination information and / or the second nomination information, to send a request to the candidate DU, in which the Petition 870250105066, dated 11 / 17 / 2025, pp. 109 / 146 Request 103 / 124 is used to request that the candidate DU provide the LTM CFRA configuration for candidate cell #1.

[00529] If the frequency of a source UE cell and the frequency of candidate cell #1 are the same, the source DU can determine the LTM CFRA configuration request for candidate cell #1. It is understood that the frequency of the source cell and the frequency of candidate cell #2 can be different.

[00530] S1510-b: The originating DU sends the request to the candidate DU, where the request is used to ask the candidate DU to provide the LTM CFRA configuration for candidate cell #1.

[00531] S1510-c: The originating DU receives the LTM CFRA configuration from candidate cell #1 from the candidate DU.

[00532] S1511-a-1: The originating DU determines, based on the LTM CFRA configuration of candidate cell #1, to trigger a PDCCH command, to instruct terminal device 120 to send an LTM CFRA preamble to candidate cell #1.

[00533] The PDCCH order includes LTM contention-free random access preamble indication information and time-frequency resource indication information.

[00534] S1511-a-2: Terminal device 120 sends the contention-free random access preamble to the candidate DU in candidate cell #1 based on the PDCCH order.

[00535] The candidate DU determines the TA of candidate cell #1 based on the contention-free random access preamble.

[00536] In S1511-a-3-1 and S1511-a-3-2, the candidate DU sends the TA of candidate cell #1 to the originating DU, and the CU can forward the TA of candidate cell #1 to the originating DU.

[00537] The originating DU determines the TA of candidate cell #2 based on the information from the first indication and the TA of candidate cell #1. The TA of candidate cell #2 and the TA of candidate cell #1 are the same, that is, the TA values ​​are the same. Petition 870250105066, dated 11 / 17 / 2025, pp. 110 / 146 104 / 124

[00538] S1511-a-3: The candidate DU sends a RAR to terminal device 120, where the RAR carries the TA (e.g., an absolute TA value) of candidate cell #1.

[00539] After S1511-a-2, S1511-a-3-1 and S1511-a-3-2 can be performed, or S1511-a-3 can be performed.

[00540] S1512: Terminal device 120 sends a measurement report of candidate cell #2 to the originating DU, in which the measurement report includes an RSRP of candidate cell #2.

[00541] S1513: The originating DU determines candidate cell 2 as a target cell for a switching operation.

[00542] S1514: The originating DU sends an LTM command to terminal device 120, where the command includes an identifier for candidate cell #2 (a cell index) and may optionally include TA indication information (e.g., TA information).

[00543] TA indication information may include a solution 1 and a TA value (the TA value and the TA value of candidate cell #1 are the same), or a solution 2 and an identifier of candidate cell #1 (for example, the identifier of candidate cell #1 indicates that the TA of candidate cell #2 is determined based on the TA of candidate cell #1, a network device considers that the TA values ​​of the two cells are the same, and furthermore, the UE also knows that the TA values ​​of the two cells are the same).

[00544] Solution 1 is applicable to a scenario where S1610-a3-1 and S1610-a-3-1 are performed, and solution 2 is applicable to a scenario where S1610-a-3 is performed. The TA of candidate cell #2 and the TA of candidate cell #1 are the same.

[00545] For S1515 and S1516, refer to the steps corresponding to Figure 3 and Figure 10.

[00546] For example, in a procedure shown in Figure 16, in an inter-DU scenario, a source DU selects an appropriate candidate cell based on frequency information of Petition 870250105066, dated 11 / 17 / 2025, pp. 111 / 146 105 / 124 an originating service cell and a candidate cell, to send a PDCCH order to a terminal device 120.

[00547] For S1601 to S1604, refer to the steps corresponding to Figure 3 and Figure 10.

[00548] S1605: A candidate DU determines to provide a CFRA configuration for a candidate cell #1 and to provide a CFRA configuration for a candidate cell #2.

[00549] The LTM CFRA of candidate cell #1 is carried in a candidate cell #1 UE context definition response message, and the LTM CFRA of candidate cell #2 is carried in a candidate cell #2 UE context definition response message. Additionally, the response message from candidate cell #1 or candidate cell #2 includes first indication information, wherein the first indication information indicates that the terminal device TAs in candidate cell #1 and candidate cell #2 may be the same. Optionally, the response message from candidate cell #1 and the response message from candidate cell #2 each include second indication information, wherein the second indication information is used for frequency information (e.g., BWP information) corresponding to a random access configuration of candidate cell #1 and / or a random access configuration of candidate cell #2.

[00550] It can be understood that the UE context definition response message from candidate cell #1 includes a configuration from candidate cell #1, but the configuration includes a configuration from an LTM cell and the LTM CFRA configuration; and the UE context definition response message from candidate cell #2 includes a configuration from candidate cell #2, but the configuration includes a configuration from an LTM cell and the LTM CFRA configuration.

[00551] S1606: A CU sends an RRC reconfiguration to the originating DU, where the RRC reconfiguration includes the Petition 870250105066, dated 11 / 17 / 2025, pp. 112 / 146 106 / 124 candidate cell #1 and candidate cell #2 settings and initial indication information.

[00552] Optionally, the RRC reconfiguration may also include the second indication information for candidate cell #1 and candidate cell #2.

[00553] For S1607 to S1609, refer to the steps corresponding to Figure 3 and Figure 10.

[00554] S1610-a: The originating DU determines, based on the frequency of the originating cell and the frequency of the candidate cell, the start of random access to candidate cell #1. In other words, the originating DU triggers the sending of a PDCCH order corresponding to candidate cell #1.

[00555] If the frequency of the UE source cell and the frequency of candidate cell #1 are equal, the source DU can determine to initiate random access to candidate cell #1. It is understood that the frequency of the source cell and the frequency of candidate cell #2 can be different.

[00556] S1610-a-1: The originating DU determines, based on the LTM CFRA configuration of candidate cell #1, to trigger the PDCCH order, to instruct terminal device 120 to send an LTM CFRA preamble to candidate cell #1.

[00557] The PDCCH order includes LTM contention-free random access preamble indication information and time-frequency resource indication information.

[00558] S1610-a-2: Terminal device 120 sends the contention-free random access preamble to the candidate DU in candidate cell #1 based on the PDCCH order.

[00559] The candidate DU determines a TA of candidate cell #1 based on the contention-free random access preamble.

[00560] In S1610-a-3-1 and S1610-a-3-2, the candidate DU sends the TA of candidate cell #1 to the originating DU, and the CU can forward the TA of candidate cell #1 to the originating DU. The originating DU determines a TA of candidate cell #2 based on the Petition 870250105066, dated 11 / 17 / 2025, pp. 113 / 146 107 / 124 indication information and in the TA of candidate cell #1. The TA of candidate cell #2 and the TA of candidate cell #1 are equal, that is, the TA values ​​are the same.

[00561] S1610-a-3: The candidate DU sends a RAR to terminal device 120, where the RAR carries the TA (an absolute TA value) of candidate cell #1.

[00562] After S1610-a-2, S1610-a-3-1 and S1610-a-3-2 can be performed, or S1610-a-3 can be performed.

[00563] S1611: Terminal device 120 sends a measurement report of candidate cell #2 to the originating DU, in which the measurement report includes an RSRP of candidate cell #2.

[00564] S1612: The originating DU determines candidate cell 2 as a target cell for a switching operation.

[00565] S1613: The originating DU sends an LTM command to terminal device 120, where the command includes an identifier for candidate cell #2 (a cell index) and may optionally include TA indication information (e.g., TA information).

[00566] TA indication information may include a solution 1 and a TA value (the TA value and the TA value of candidate cell #1 are the same), or a solution 2 and an identifier of candidate cell #1 (for example, the identifier of candidate cell #1 indicates that the TA of candidate cell #2 is determined based on the TA of candidate cell #1, a network device considers that the TA values ​​of the two cells are the same, and furthermore, the UE also knows that the TA values ​​of the two cells are the same).

[00567] Solution 1 is applicable to a scenario where S1610-a3-1 and S1610-a-3-2 are performed, and solution 2 is applicable to a scenario where S1610-a-3 is performed. The TA of candidate cell #2 and the TA of candidate cell #1 are the same.

[00568] For S1614 and S1615, refer to the steps corresponding to Figure 3 and Figure 10. Petition 870250105066, dated 11 / 17 / 2025, pp. 114 / 146 108 / 124

[00569] It should be noted that similar expressions in Figure 8 to Figure 16 can be mutually referenced.

[00570] The foregoing describes the embodiments of the method in the embodiments of this application, and the following describes the embodiments of the corresponding apparatus.

[00571] To implement functions in the methods provided in the 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. Whether a function is implemented 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.

[00572] Figure 17 is a block diagram of a 1700 communication device according to an embodiment of this application. The 1700 communication device may be the network device (e.g., the access network device) or the terminal device in the previous embodiment, or it may be a chip or module in the network device or terminal device, and is configured to implement the method in the previous embodiment. The 1700 communication device includes a 1710 transceiver module. The 1710 transceiver module is described below by means of an example.

[00573] The 1710 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 1710 transceiver module may also include a processing module, configured to implement a function other than transmit or receive.

[00574] When the 1700 communication device is configured to implement a network device function, for example, Petition 870250105066, dated 11 / 17 / 2025, pp. 115 / 146 109 / 124 The 1710 transceiver module is configured to receive a contention-free random access preamble 1 in a candidate cell 1. The 1710 transceiver module is further configured to send a target cell identifier from a switching, target cell TA information, and the like to a terminal device.

[00575] Optionally, the communication device 1700 may also include a processing module 1720, configured to perform a function other than receiving and sending functions, for example, determining a TA of candidate cell 1 based on the contention-free random access preamble 1 of candidate cell 1.

[00576] Optionally, the communication device 1700 also includes a storage module 1730 (not shown in Figure 17), configured to store a program or code used to perform the previous method.

[00577] The content is used for example purposes only. When the 1700 communication device is configured to implement a network device function, the 1700 communication device is responsible for performing the method or steps related to the network device in the previous method mode.

[00578] The communication device 1700 is a terminal device. For example, the transceiver module 1710 is configured to receive a TA from a candidate cell 1. The transceiver module 1710 is further configured to receive an identifier from a target cell of a switching and identification information from candidate cell 1.

[00579] It should be understood that when the communication device 1700 is the terminal device, the transceiver module 1710 may be a module that is in a control unit / subscriber unit / distributed unit of the terminal device and that is configured to implement receive and send functions. Petition 870250105066, dated 11 / 17 / 2025, pp. 116 / 146 110 / 124

[00580] Optionally, the 1700 communication device may also include a 1720 processing module, configured to perform a function other than receiving and sending functions, and the like.

[00581] Optionally, the communication device 1700 also includes a storage module 1730 (not shown in Figure 17), configured to store a program or code used to perform the previous method.

[00582] The content is used for example purposes only. When the 1700 communication device is configured to implement a terminal device function, the 1700 communication device is responsible for performing the method or steps related to the terminal device in the previous method mode.

[00583] Furthermore, for the implementation of each operation in Figure 17, refer to the corresponding descriptions of the content shown in the previous method's embodiment. Details are not described again in this document.

[00584] Figure 18 is a block diagram of an 1800 communication device according to an embodiment of this application. The 1800 communication device includes an 1810 processor and an 1820 communication interface. The 1810 processor and the 1820 communication interface can be connected to each other via an 1840 bus (which is not shown in Figure 18). The 1800 communication device can be configured to implement a terminal device function and can also be configured to implement a network device function.

[00585] Optionally, the 1800 communication device also includes an 1830 memory.

[00586] The 1830 memory includes, among others, random access memory (RAM), read-only memory (ROM), and erasable programmable read-only memory. Petition 870250105066, dated 11 / 17 / 2025, pp. 117 / 146 111 / 124 memory, EPROM) or a portable read-only memory (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 this. For example, 1830 memory is configured to store instructions and related data.

[00587] In embodiments 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 embodiments of this application. The general-purpose processor may be a microprocessor or any conventional or similar processor. The method steps disclosed with reference to embodiments of this application may be completed directly by a hardware processor or may be completed using a combination of hardware in the processor and a software module. For example, the 1810 processor may be one or more central processing units (CPUs).When the 1810 processor is a CPU, the CPU can be either a single-core CPU or a multi-core CPU.

[00588] When the communication device 1800 is configured to implement the terminal device function, for example, the processor 1810 is configured to perform the following operations: receive TA information from a candidate cell 1; and receive an identifier from a target cell of a switching and identification information from candidate cell 1.

[00589] The content is used for example purposes only. When the 1800 communication device is configured to implement the terminal device function, the device of Petition 870250105066, dated 11 / 17 / 2025, pp. 118 / 146 112 / 124 communication 1800 is responsible for carrying out the method or steps related to the terminal device in the previous method mode.

[00590] When the communication device 1800 is configured to implement the network device function, for example, the processor 1810 is configured to perform the following operations: receive a contention-free random access preamble in a candidate cell 1; and send a target cell identifier of a switching and timing advance information TA of the target cell to a terminal device.

[00591] The content is used only as an example for description. When the 1800 communication device is configured to implement the network device function, the 1800 communication device is responsible for performing the method or steps related to the network device in the previous method mode.

[00592] The preceding descriptions are merely exemplary. For specific content, refer to the content shown in the embodiment of the method. In addition, for the implementation of each operation in Figure 18, refer to the corresponding descriptions of the embodiments of the method shown in Figures 3 to 16.

[00593] The communication devices shown in Figures 17 and 18 are configured to implement the content described in the previous method embodiments. Therefore, for specific implementation steps and methods for the communication devices shown in Figures 12 and 18, refer to the content described in the previous method embodiments.

[00594] It should be understood that the transceiver module above 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. Petition 870250105066, dated 11 / 17 / 2025, pp. 119 / 146 113 / 124 For ease of description, the sending module and the receiving module are combined into a single transceiver module in the modes of this application. Unified descriptions are provided in this document. Details are not described again below.

[00595] Figure 19 is a diagram of a 1900 communication device according to an embodiment of this application. The 1900 communication device can be configured to implement a function of the network device or terminal device in the previous method. The 1900 communication device can be a chip in the network device or terminal device. The 1900 communication device includes an input / output interface 1920 and a processor 1910. The input / output interface 1920 can be an input / output circuit. The processor 1910 can be a signal processor, a chip, or other integrated circuit that can implement the methods of this application. The input / output interface 1920 is configured for input or output of a signal or data.

[00596] For example, when the communication device 1900 is a terminal device, the input / output interface 1920 is configured to receive configuration information from a network device. The input / output interface 1920 is further configured to receive TA information from a candidate cell 1. The input / output interface 1920 receives an identifier from a target cell of a switching and identification information from candidate cell 1. The processor 1910 is further configured to perform some or all of the steps of any method provided in this application.

[00597] For example, when the communication device 1900 is a network device, the input / output interface 1920 is configured to receive a contention-free random access preamble in a candidate cell 1. The input / output interface 1920 is further configured to send an identifier of a target cell for switching and information. Petition 870250105066, dated 11 / 17 / 2025, pp. 120 / 146 114 / 124 timing advance TA from the target cell to a terminal device.

[00598] In one possible implementation, the 1910 processor executes instructions stored in memory, to implement the function implemented by the first communication device or the network device.

[00599] Optionally, the 1900 communication device also includes memory. Optionally, the processor and memory are integrated. Optionally, the memory is located outside the 1900 communication device.

[00600] In one possible implementation, the 1910 processor could be a logic circuit, and the 1910 processor could emit a message or signal via the 1920 input / output interface. The logic circuit could be a signal processor, a chip, or another integrated circuit that could implement the methods in embodiments of this application.

[00601] The previous descriptions of the 1900 communication apparatus in Figure 19 are merely exemplary. The 1900 communication apparatus can be configured to perform the methods of the previous embodiments. For specific content, refer to the descriptions of the embodiments of the previous methods. Details will not be described again in this document.

[00602] Figure 20 is a block diagram of a 2000 communication device according to an embodiment of this application. The 2000 communication device can be a network device or a chip. The 2000 communication device can be configured to perform the above operations performed by the network device.

[00603] When the communication device 2000 is a network device, for example, a base station, Figure 20 is a diagram of a simplified structure of the base station. The base station includes a 2010 module, a 2020 module, and a 2030 module. The 2010 module is configured primarily to: perform processing Petition 870250105066, dated 11 / 17 / 2025, pp. 121 / 146 115 / 124 baseband, controlling the base station and similar. The 2010 module is generally a base station control center, commonly called a processor, and is configured to control the base station to perform a processing operation on a network device in the modes of the previous methods. The 2020 module is mainly configured to store computer program code and data. The 2030 module is mainly configured to receive and send a radio frequency signal and perform the conversion between the radio frequency signal and a baseband signal. The 2030 module may commonly be called a transceiver module, transceiver machine, transceiver circuit, transceiver, or similar.A transceiver module in module 2030 may also be called a transceiver machine, transceiver, or similar, and includes an antenna 2033 and a radio frequency circuit (not shown in Figure 20), wherein the radio frequency circuit is primarily configured to perform radio frequency processing. Optionally, a component configured to implement a receiving function and located in module 2030 may be considered a receiver, and a component configured to implement a sending function may be considered a transmitter. In other words, module 2030 includes a receiver 2032 and a transmitter 2031. The receiver may also be called a receiver module, receiving machine, receiver circuit, or similar, and the transmitter may be called a transmitter module, transmitting machine, transmitter circuit, or similar.

[00604] The 2010 module and the 2020 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. Petition 870250105066, dated 11 / 17 / 2025, pp. 122 / 146 116 / 124 si to enhance processing capacity. In an optional implementation, multiple boards can share one or more processors, multiple boards can share one or more memories, or multiple boards can share one or more processors simultaneously.

[00605] In one implementation, the transceiver module in module 2030 is configured to execute a process related to the reception and transmission performed by the network device in the modes shown in Figures 3 to 16. The processor in module 2010 is configured to perform a process related to the processing performed by the network device in the modes shown in Figures 3 to 16.

[00606] In another implementation, the processor in module 2010 is configured to perform a process related to the processing performed by the network device in the modes shown in Figure 3 to Figure 16.

[00607] In another implementation, the transceiver module in module 2030 is configured to perform a process related to receiving and sending data performed by the network device in the modes shown in Figure 3 to Figure 16.

[00608] It should be understood that Figure 20 is merely an example and not a limitation, and the preceding network device, including the processor, memory, and transceiver, may not depend on the structures shown in Figures 12 to 14.

[00609] When the communication device 2000 is a chip, it includes a transceiver, memory, and a processor. 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 sending operation performed by the network device in the previous method modes can be understood as an output from the chip, and a receiving operation performed by the network device in the previous method modes can be understood as Petition 870250105066, dated 11 / 17 / 2025, pp. 123 / 146 117 / 124 as the chip input.

[00610] Figure 21 is a block diagram of a 2100 communication device according to an embodiment of this application. The 2100 communication device can be a terminal device, a terminal device processor, or a chip. The 2100 communication device can be configured to perform an operation performed by the terminal device in the previous method embodiments.

[00611] When the communication apparatus 2100 is the terminal device, Figure 21 is a diagram of a simplified structure of the terminal device. As shown in Figure 21, the terminal device includes a processor, a memory, and a transceiver. The memory can store computer program code. The transceiver includes a transmitter 2131, a receiver 2132, a radio frequency circuit (not shown in Figure 21), an antenna 2133, and an input / output apparatus (not shown in Figure 21).

[00612] 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. Memory is primarily configured to store the software program and data. The radio frequency circuit is primarily configured to: perform the conversion between a baseband signal and a radio frequency signal and process the radio frequency signal. The antenna is primarily configured to receive and transmit 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 output data to the user. It should be noted that some types of terminal devices may not have an input / output device. Petition 870250105066, dated 11 / 17 / 2025, pp. 124 / 146 118 / 124

[00613] When sending data, after performing baseband processing on the data to be sent, the processor emits a baseband signal to the radio frequency circuit; 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 data is sent to the terminal device, the radio frequency circuit receives the 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 it. For ease of description, Figure 21 shows only one memory, one processor, and one transceiver. A real terminal device may include one or more processors and one or more memories.Memory can also be called storage medium, 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 possibilities of this term.

[00614] 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.

[00615] As shown in Figure 21, the terminal device includes a processor 2110, a memory 2120, and a transceiver 2130. The processor 2110 may also be called a processing unit, processing board, processing module, processing apparatus, or similar, and the transceiver 2130 may also be called a transceiver unit, transceiver machine, transceiver apparatus, or similar.

[00616] Optionally, a component present in the transceiver Petition 870250105066, dated 11 / 17 / 2025, pp. 125 / 146 119 / 124 A 2130 transceiver configured to implement a receiving function can be considered a receiving module, and a component present in the 2130 transceiver and configured to implement a sending function can be considered a sending module. That is, the 2130 transceiver includes a receiver and a transmitter. The transceiver may also sometimes be called a transceiver machine, transceiver module, transceiver circuit, or similar. The receiver may also sometimes be called a receiving machine, receiver module, receiver circuit, or similar. The transmitter may also sometimes be called a transmitting machine, transmitter module, transmitter circuit, or similar.

[00617] For example, in one implementation, processor 2110 is configured to perform a processing action on the terminal device side in modes shown in Figures 3 to 16, and transceiver 2130 is configured to perform receive and send actions on the terminal device side in Figures 3 to 16.

[00618] For example, in one implementation, processor 2110 is configured to perform a processing action on the terminal device side in modes shown in Figures 3 to 16, and transceiver 2130 is configured to perform receive and send actions on the terminal device side in Figures 3 to 16.

[00619] It should be understood that Figure 21 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 Figures 17 to 19.

[00620] When the 2100 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 870250105066, dated 11 / 17 / 2025, pp. 126 / 146 120 / 124 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.

[00621] 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.

[00622] 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.

[00623] 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 previous embodiments.

[00624] 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.

[00625] This application also provides a computer program. When the computer program is run on a computer, the method of the previous embodiment is implemented.

[00626] Another embodiment of this application provides a computer-readable storage medium. The computer-readable storage medium stores a computer program. Petition 870250105066, dated 11 / 17 / 2025, pp. 127 / 146 121 / 124 When the computer program is executed by a computer, the method of the previous modality is implemented.

[00627] In the descriptions of embodiments in this application, unless otherwise specified, 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.

[00628] Furthermore, to clearly describe the technical solutions in embodiments of this application, terms such as first and second are used in embodiments of this application to distinguish between identical 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. In addition, in embodiments of this application, words such as example or for example are used to represent an example or description.

[00629] In the modality descriptions of this request, unless otherwise specified, / represents an association relationship between associated objects. For example, A / B can represent A or B. In this request, and / or describes only an association relationship between associated objects and represents the possibility of there being three relationships. For example, A and / or B can represent the following three cases: Only A exists, A and B exist, and only B exists, where A and B can be singular or plural.

[00630] The sequence numbers of the processes above do not represent execution sequences in the modes of this request. The execution sequences of the processes must be determined based on the functions and internal logic of the processes and should not be interpreted as any limitation to the processes of Petition 870250105066, dated 11 / 17 / 2025, pp. 128 / 146 122 / 124 implementation of the modalities of this request.

[00631] A person skilled in the art may be aware that, in combination with the examples described in the embodiments disclosed in this specification, algorithm units and steps may be implemented by electronic hardware or by a combination of 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 specific application, but the implementation should not be considered to go beyond the scope of this application.

[00632] It may be clearly understood by a person skilled in the art that, for the sake of convenient and brief description, for a detailed working process of the aforementioned system, apparatus and unit, one should refer to a corresponding process in the aforementioned method modalities. Details are not described again in this document.

[00633] In the various embodiments provided in this application, it should be understood that the disclosed system, apparatus, and method may be implemented in other ways. For example, the embodiment of the apparatus described is merely an example. For example, the division into units is merely a logical function division and may be another division in the actual implementation. For example, a plurality of units or components may be combined or integrated into another system, or some functionalities may be omitted or not performed.

[00634] Furthermore, the mutual couplings or 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. Petition 870250105066, dated 11 / 17 / 2025, pp. 129 / 146 123 / 124

[00635] 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 the actual requirements to achieve the objectives of the modal solutions.

[00636] Furthermore, 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.

[00637] When functions are implemented in the form of a functional software unit and sold or used as a standalone product, the functions may be stored on a computer-readable storage medium. Based on this understanding, the technical solutions in embodiments of this application, essentially, either 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, or the like) to perform all or some of the steps of the methods in embodiments of this application.The aforementioned storage medium includes any medium that can store program code, for example, a USB flash drive, a removable hard drive, a ROM, a RAM, a magnetic disk, or an optical disk.

[00638] Mutual references may be made to the content in different forms of this application. Unless otherwise stated or in the event of a logical conflict, the terms and / or descriptions in different forms are consistent and may be mutually referenced, as may the technical resources in different forms. Petition 870250105066, dated 11 / 17 / 2025, pp. 130 / 146 124 / 124 can be combined into a new modality based on an internal logical relationship between the technical resources.

[00639] It may be understood that, in embodiments of this application, the terminal device and the network device may perform some or all of the steps described in this application. These steps or operations are merely exemplary. In 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 that shown in the embodiments of this application, and not all operations described in this application may be performed. Petition 870250105066, dated 11 / 17 / 2025, pp. 131 / 146

Claims

1 / e CLAIMS 1. A communication method, characterized in that the method is applied to a terminal device or to a chip in the terminal device and comprises: receiving a timing advance TA from a first candidate cell; and receiving an identifier of a target cell from a switch and identification information of the first candidate cell, wherein the target cell is a second candidate cell, and the identification information of the first candidate cell indicates to determine a TA of the target cell based on the TA of the first candidate cell.

2. Method according to claim 1, characterized in that the method further comprises: sending a measurement report of the second candidate cell.

3. A method according to claim 1 or 2, characterized in that the method further comprises: receiving indication information, wherein the indication information indicates the sending of a contention-free random access preamble in the first candidate cell, and the contention-free random access preamble is used to determine the TA of the first candidate cell; and sending the contention-free random access preamble in the first candidate cell based on the indication information.

4. A method according to any one of claims 1 to 3, characterized in that the first candidate cell and the second candidate cell belong to a first network device, and the first candidate cell is different from the second candidate cell.

5. A method, according to any one of claims 1 to 4, characterized in that the TA of the first candidate cell and the TA of the target cell are the same.

6. Method, according to any of the claims in Petition 870250090195, dated 10 / 03 / 2025, page 22 / 38 1 to 5, characterized in that the first candidate cell and the second candidate cell belong to a set of candidate target cells of the switch.

7. A communication method, characterized in that it comprises: receiving, by a first network device, a contention-free random access preamble of a first candidate cell; and sending, by the first network device, an identifier of a target cell of a switch and timing advance information TA of the target cell to a terminal device, wherein the target cell is a second candidate cell, and the TA information of the target cell is determined based on the contention-free random access preamble of the first candidate cell.

8. Method, according to claim 7, characterized in that the target cell TA information comprises at least one of the following: a target cell TA or identification information of the first candidate cell, wherein the identification information of the first candidate cell indicates the determination of the target cell TA based on the first candidate cell.

9. Method according to claim 7 or 8, characterized in that the method further comprises: sending, by the first network device, indication information to the terminal device, wherein the indication information indicates the sending of the contention-free random access preamble in the first candidate cell; and the indication information comprises contention-free random access configuration information of the first candidate cell, and the contention-free random access configuration information is used for transmission of the contention-free random access preamble.

10. Method according to claim 9, characterized in that the method further comprises: sending, via the first network device, configuration information of the first candidate cell and configuration information of the second candidate cell to the terminal device.

11. A method according to any one of claims 7 to 10, characterized in that the first candidate cell and the second candidate cell belong to the first network device, and the first candidate cell is different from the second candidate cell.

12. Method, according to any one of claims 7 to 11, characterized in that the TA of the first candidate cell and the TA of the target cell are the same.

13. A method, according to any one of claims 7 to 12, characterized in that the first candidate cell and the second candidate cell belong to a set of candidate target cells of the switch.

14. Communication method, characterized by the fact that it comprises: receiving, by a first network element, an uplink Radio Resource Control (RRC) message transmission from a third network element; determining, by the first network element, to initiate a transfer configuration procedure; sending, by the first network element, a first message to a second network element, wherein the first message comprises an identifier of a first candidate cell and an identifier of a second candidate cell, and further comprises indication information to request initial configuration information for the first candidate cell, in Petition 870250090195, dated 03 / 10 / 2025, p.24 / 38 ^ / Ί that the first configuration information is used for contention-free random access; and to receive, by the first network element, the first configuration information from the second network element, where the first configuration information is contained in a first response.

15. A method according to claim 14, characterized in that the initial configuration information comprises: time-frequency resource indication information for transmitting a contention-free random access preamble in the first candidate cell and / or a contention-free random access preamble identifier, wherein the time-frequency resources of the contention-free random access preamble are associated with a Synchronization Signal Block and Physical Broadcast Channel (SSB), and wherein the contention-free random access preamble identifier and / or the time-frequency resources for contention-free random access are used to identify a terminal within the first candidate cell.

16. Method, according to claim 14 or 15, characterized in that the indication information is still used to indicate that the first response comprises the first configuration information.

17. A method according to any one of claims 14 to 16, characterized in that the first message is a request message for EU context configuration, and the first response is a response message for EU context configuration.

18. Method, according to any one of claims 14 to 17, characterized in that the method further comprises: sending, by the second network element, the first response Petition 870250090195, dated 03 / 10 / 2025, page 25 / 38 5 / Ί to the first network element, wherein, in response to the first message comprising the indication information, the first response comprises the first configuration information.

19. A communication method characterized in that it comprises: receiving, by a second network element, a first message from a first network element, wherein the first message comprises an identifier of a first candidate cell and an identifier of a second candidate cell, and further comprises indication information to request first configuration information for the first candidate cell, wherein the first configuration information is used for contention-free random access; and sending, by the second network element, the first configuration information to the first network element, wherein the first configuration information is contained in a first response.

20. A method according to claim 19, characterized in that the initial configuration information comprises: time-frequency resource indication information for transmitting a contention-free random access preamble in the first candidate cell and / or a contention-free random access preamble identifier, wherein the time-frequency resources of the contention-free random access preamble are associated with a Synchronization Signal Block and Physical Broadcast Channel (SSB), and wherein the contention-free random access preamble identifier and / or the time-frequency resources for contention-free random access are used to identify a terminal within the first candidate cell.

21. Method, according to claim 19 or 20, Petition 870250090195, dated 10 / 03 / 2025, page 26 / 38 6 / Ί characterized in that the indication information is still used to indicate that the first response comprises the first configuration information.

22. A method according to any one of claims 19 to 21, characterized in that the first message is a request message for EU context configuration, and the first response is a response message for EU context configuration.

23. A method according to any one of claims 19 to 22, characterized in that the sending, by the second network element, of the first configuration information to the first network element, comprises: sending, by the second network element, the first reply to the first network element, wherein, in reply to the first message comprising the indication information, the first reply comprises the first configuration information.

24. Communication apparatus, comprising a processor, characterized in that the processor is configured to execute a computer program or instructions, or the processor is configured to enable, by means of a logic circuit, the communication apparatus to perform the method as defined in any one of claims 1 to 6, or to perform the method as defined in any one of claims 7 to 13, or to perform the method as defined in any one of claims 14 to 18, or to perform the method as defined in any one of claims 19 to 23.

25. Communication apparatus, according to claim 24, characterized in that the communication apparatus further comprises a memory, and the memory is configured to store the computer program or instructions.

26. Communication apparatus, according to claim 24 or 25, characterized in that the communication apparatus further comprises a communication interface, and the communication interface is configured to input a signal and / or emit a signal.

27. Communication apparatus, comprising a logic circuit and an input / output interface, characterized in that the input / output interface is configured to input a signal and / or emit a signal; and the logic circuit is configured to perform the method as defined in any one of claims 1 to 6, or to perform the method as defined in any one of claims 7 to 13, or to perform the method as defined in any one of claims 14 to 18, or to perform the method as defined in any one of claims 19 to 23.

28. Computer-readable storage medium, characterized in that the computer-readable storage medium stores 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 23 is performed.

29. Computer program product, comprising instructions, characterized in that when the instructions are run on a computer, the method as defined in any one of claims 1 to 23 is performed. Petition 870250090195, dated 10 / 03 / 2025, pp. 28 / 38

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