Communication methods and related devices

Abstract

Embodiments of this application disclose a communication method and associated apparatus that enable a terminal device to determine the access status of random access while reducing service interruption time for the terminal device in a serving cell. The method in embodiments of this application includes: A terminal device sends a random access request to a neighboring cell network device, the random access request is used to initiate random access to a target neighboring cell, which is a neighboring cell of the terminal device's serving cell. If the terminal device does not receive a feedback message from the serving network device regarding the random access request, or receives at least one of a first feedback message or a first scheduling signaling from the serving network device, the terminal device retransmits the random access request to the neighboring cell network device, the first feedback message indicating that the terminal device's random access failed, and the first scheduling signaling is used to schedule the terminal device to retransmit the random access request.

Description

Technical Field

[0001] This application relates to the field of communication technologies, and in particular, to communication methods and related devices.

Background Art

[0002] When a terminal device performs cell handover, the terminal device cannot receive data or information from the serving cell. As a result, the service of the serving cell of the terminal device is interrupted. In order to reduce the service interruption time of the serving cell of the terminal device, before the terminal device performs cell handover, the terminal device needs to obtain in advance the uplink timing advance of the terminal device in the candidate cell to which the terminal device will handover (T A) is agreed upon in the standard. Specifically, the terminal device is located in the serving cell, and the terminal device may start a random access to the candidate cell. The specific random access procedure includes the following. The terminal device sends a preamble to the candidate cell. Then, the terminal device waits to receive a response message from the candidate cell for the preamble, and the response message includes the TA of the terminal device in the candidate cell.

[0003] However, in the random access procedure, the terminal device cannot continue to communicate with the serving cell. Therefore, the service of the serving cell is interrupted. In order to further reduce the service interruption time of the serving cell of the terminal device, the following solution is proposed. After sending the preamble, the terminal device does not need to wait to receive a response message from the candidate cell. The serving cell can obtain the TA of the candidate cell from the candidate cell and send the TA to the terminal device by using a handover command.

[0004] However, if the terminal device does not wait for a response message from a candidate cell regarding the preamble, the terminal device cannot determine whether its random access was successful. Therefore, how the terminal device determines the access status of random access while reducing service interruption time for the terminal device in the serving cell is an urgent issue that needs to be resolved. [Overview of the project]

[0005] This application provides a communication method and related apparatus, which, as a result, allows a terminal device to determine whether a random access initiated by the terminal device to a target neighboring cell was successful, based on the feedback status of a serving network device. In this way, the terminal device can determine the access status of a random access while reducing the service interruption time of the terminal device in the serving cell.

[0006] A first aspect of this application provides a communication method including the following:

[0007] A terminal device sends a random access request to a neighboring cell network device, where the random access request is used to initiate random access to a target neighboring cell, which is a neighboring cell of the terminal device's serving cell. The terminal device resends the random access request to the neighboring cell network device if it does not receive a feedback message from the serving network device about the random access request, or if it receives at least one of a first feedback message or a first scheduling signal from the serving network device, where the first feedback message indicates that the terminal device's random access failed, and the first scheduling signal is used to schedule the terminal device to resend the random access request.

[0008] From the above technical solution, it can be understood that the terminal device does not need to wait for a response from a neighboring cell network device for a random access request, but waits for a feedback message from the serving network device for the random access request, thereby helping to reduce the service interruption time for the terminal device in the serving cell. Furthermore, if the terminal device does not receive a feedback message from the serving network device for the random access request, or if the terminal device receives at least one of the first feedback message or the first scheduling signaling from the serving network device, the terminal device may retransmit the random access request to the neighboring cell network device. In this way, the terminal device can determine whether the random access was successful based on the feedback status of the serving network device. Thus, in the technical solution of this application, the terminal device can determine the access status of a random access while reducing the service interruption time for the terminal device in the serving cell.

[0009] Based on the first aspect, in possible implementations, the method further includes: The terminal device determines that its random access was successful when it receives a second feedback message from the serving network device, the second feedback message indicating that the neighboring cell network device has successfully received the random access request.

[0010] In this implementation, the terminal device can determine that its random access was successful by receiving a second feedback message from a neighboring cell network device. The terminal device does not need to wait for a response from a neighboring cell network device for the random access request, but waits for a feedback message from the serving network device for the random access request, thereby helping to reduce the service interruption time for the terminal device in the serving cell. Thus, in the technical solution of this application, the terminal device can determine the access status of a random access while reducing the service interruption time for the terminal device in the serving cell.

[0011] Based on the first aspect, in possible implementations, the method further includes: The terminal device determines that the random access was successful when it receives first indication information from the serving network device, where the first indication information indicates that the terminal device should not retransmit the random access request to the neighboring cell network device. In this implementation, the terminal device may indirectly determine that the random access was successful based on the first indication information. The terminal device does not need to wait for a response from the neighboring cell network device regarding the random access request, but waits for a feedback message from the serving network device regarding the random access request. In this way, the terminal device can determine the access status of the random access while reducing the service interruption time for the terminal device in the serving cell.

[0012] Based on the first aspect, in possible implementations, the second feedback message further includes at least one of the following: the TA of the target neighboring cell, the identifier assigned to the terminal device by the target neighboring cell, or the uplink resource assigned to the terminal device by the target neighboring cell. This helps the terminal device communicate with the target neighboring cell. Before the terminal device hands over to the target neighboring cell, the neighboring cell network device assigns the corresponding identifier, uplink resource, and TA to the terminal device. Thus, before handing over to the target neighboring cell, the terminal device obtains the information shown above in advance, thereby reducing the service interruption time for the terminal device in the serving cell during cell handover.

[0013] Based on the first aspect, in possible implementations, a terminal device retransmitting a random access request to a neighboring cell network device includes: The terminal device retransmits the random access request to a neighboring cell network device based on a predetermined number of retransmissions and / or predetermined power ramping parameters.

[0014] In this implementation, the terminal device can increase the power to send random access requests based on pre-configured power ramping parameters and retransmit random access requests based on the number of retransmissions. This helps improve the success rate of random access and prevents consecutive random access failures caused by insufficient transmit power or poor channel conditions, thereby improving the access efficiency of random access and avoiding resource waste.

[0015] Based on the first aspect, in possible implementations, the first feedback message or first scheduling signaling further includes power ramping parameters, and the terminal device retransmits a random access request to a neighboring cell network device includes: The terminal device retransmits a random access request to a neighboring cell network device based on the power ramping parameters.

[0016] In this implementation, the first feedback message or second scheduling signaling further includes power ramping parameters, which in turn allow the terminal device to increase the power to send random access requests based on these parameters. This helps improve the success rate of random access requests and prevents consecutive random access failures caused by insufficient transmission power, thereby improving the access efficiency of random access requests and avoiding resource waste.

[0017] Based on the first aspect, in possible implementations, the method further includes: a terminal device receives a handover command from a serving network device, where the handover command indicates that the terminal device should hand over to a target neighboring cell. This helps the terminal device hand over to a target neighboring cell. Note that this implementation may be used as an alternative, independent solution and is not dependent on the above implementation.

[0018] Based on the first aspect, in possible implementations, after a terminal device receives a handover command from a serving network device, the method further includes: the terminal device determines at least one of the following: an uplink resource, an uplink transmit beam, an uplink transmit power, or a TA of a target neighboring cell, where the uplink resource is used by the terminal device to perform uplink transmissions with a target neighboring cell; the uplink transmit beam is a beam used by the terminal device to perform uplink transmissions with a target neighboring cell; the uplink transmit power is the power used by the terminal device to perform uplink transmissions with a target neighboring cell; and the TA of a target neighboring cell is a TA used by the terminal device to transmit uplink signals to a target neighboring cell. In this implementation, the terminal device may determine at least one of the above information, and as a result, the terminal device can communicate with a neighboring cell network device.

[0019] Based on the first aspect, in possible implementations, the determination of uplink resources by the terminal device includes: the terminal device selects a pre-configured individual physical uplink control channel (P UCCH) Resource or pre-configured Grant Physical Shared Channel (C The G-PUSCH resource is used as the uplink resource, or the terminal device determines the uplink resource by using a handover command, where the handover command includes the uplink resource, or the terminal device monitors a second scheduling signaling sent by a neighboring cell network device on a pre-configured time-frequency resource, where the second scheduling signaling indicates the uplink resource. This implementation shows several possible implementations in which the terminal device determines the uplink resource, thereby enriching the implementation of the solution.

[0020] Based on the first aspect, in a possible implementation, the determination of uplink transmit power by a terminal device includes: the terminal device determines the path loss between the terminal device and a neighboring cell network device based on a first path loss reference signal, and the terminal device determines the uplink transmit power based on the path loss. This implementation shows a possible implementation in which the terminal device determines the uplink transmit power, thereby facilitating the implementation of the solution.

[0021] Based on the first aspect, in possible implementations, the determination of uplink transmit power by a terminal device includes: the terminal device uses the transmit power for sending random access requests by the terminal device as the uplink transmit power. Another implementation is shown in which the terminal device determines the uplink transmit power, and as a result the terminal device can communicate with neighboring cell network devices.

[0022] Based on the first aspect, in possible implementations, the handover command is triggered by the activated transmit setting indicator of the target neighboring cell. (T If the CI) state is further included, the first path loss reference signal is the path loss reference signal associated with the activated TCI state, or if the handover command further includes the deactivated TCI state of the target neighboring cell, the first path loss reference signal is associated with the random access resource used by the terminal device to send the random access request. Synchronization signal and Physical broadcast channel block ( SS / PBCH block If the handover command is either (SSB) or further includes a reference signal for the target neighbor cell, the first path loss reference signal is the reference signal for the target neighbor cell. This implementation shows several possible implementations in which the terminal device determines the first path loss reference signal, thereby helping the terminal device determine the uplink transmit power.

[0023] Based on the first aspect, in possible implementations, the handover command further includes power control parameters associated with the activated TCI state of the target neighbor cell, or power control parameters associated with the deactivated TCI state of the target neighbor cell, and the terminal device determines the uplink transmit power based on path loss, which includes: The terminal device determines the uplink transmit power based on path loss and power control parameters. In this implementation, the handover command further carries power control parameters, and the terminal device may determine the uplink transmit power based on path loss and power control parameters. This helps the terminal device perform uplink transmissions with serving network devices by using appropriate uplink transmit power, thereby improving communication transmit performance.

[0024] Based on the first aspect, in possible implementations, the determination of the TA of the target neighbor cell by the terminal device includes: if the handover command includes the TA of the target neighbor cell, the terminal device uses the TA in the handover command as the TA of the target neighbor cell; or if the handover command does not include the TA of the target neighbor cell, the terminal device defaults to assuming the TA of the target neighbor cell is equal to 0; or if the handover command does not include the TA of the target neighbor cell, the terminal device uses the TA carried in the second feedback message as the TA of the target neighbor cell; or if the handover command includes an uplink timing advance indication and the uplink timing advance indication indicates that the terminal device should determine the TA of the target neighbor cell, the terminal device uses the TA of the target neighbor cell determined by the terminal device as the TA of the target neighbor cell; or if the handover command includes a timing advance group identifier (TWhen including the TA associated with the TAG ID in the AG ID), the TA associated with the TAG ID is used as the TA of the target neighboring cell, or when the handover command does not include the TA of the target neighboring cell and the target neighboring cell is the current serving cell of the terminal device, the terminal device uses the TA of the serving cell as the TA of the target neighboring cell. In this implementation, multiple possible implementations for the terminal device to determine the TA of the target neighboring cell are shown, whereby this helps the terminal device to perform uplink transmission with the neighboring cell network device and improves the communication transmission performance.

[0025] Based on the first aspect, in a possible implementation, for the terminal device to determine the uplink transmission beam includes the following. When the handover command includes the TCI state indicated by the neighboring cell network device for the terminal device, the terminal device determines the uplink transmission beam based on the TCI state indicated in the handover command, or when the TCI state indicated in the handover command is a downlink TCI state, the terminal device determines the uplink transmission beam based on the reception beam of the SSB associated with the random access resource used to send a random access request. In this implementation, multiple possible implementations for the terminal device to determine the uplink transmission beam are shown, whereby this helps the terminal device to perform uplink transmission with the neighboring cell network device and improves the communication transmission performance.

[0026] Based on the first embodiment, in possible implementations, the first scheduling signaling includes second indication information, which indicates that the terminal device should retransmit the random access request. In this implementation, the second indication information explicitly indicates that the terminal device should retransmit the random access request. In this way, the terminal device is notified to retransmit the random access request, and as a result, the terminal device retransmits the random access request by using an appropriate number of appropriate transmit power and retransmissions. This improves the success rate of random access for the terminal device.

[0027] Based on the first aspect, in possible implementations, the first scheduling signaling further includes at least one of a third indication information or a power ramping parameter, the third indication information indicating whether the terminal device should increase power to send out a random access request, and the power ramping parameter including a power ramping value or a power ramping stage. In this implementation, the first scheduling signaling further includes the third indication information and / or a power ramping parameter. The terminal device may decide whether to increase power to send out a random access request based on the third indication information, and then increase power to send out a random access request based on the power ramping parameter. This helps to improve the success rate of random access for the terminal device.

[0028] Based on the first aspect, in a possible implementation, the method further includes the following. The terminal device receives fourth indication information from the serving network device, where the fourth indication information indicates that the terminal device does not need to wait for a feedback message from the neighboring cell network device regarding the random access request, and the terminal device continues to communicate with the serving network device without waiting for a feedback message from the neighboring cell network device regarding the random access request. In this way, whether the terminal device waits for a feedback message from the neighboring cell network device is flexibly set.

[0029] Based on the first aspect, in a possible implementation, before the terminal device sends a random access request to the neighboring cell network device, the method further includes the following. The terminal device receives third scheduling signaling from the serving network device, where the third scheduling signaling is used to schedule the terminal device to start a random access to the target neighboring cell. In this way, the terminal device starts a random access to the neighboring cell network device.

[0030] Based on the first aspect, in a possible implementation, the third scheduling signaling is carried in DCI, and the DCI further indicates that the terminal device receives a feedback message from the serving network device regarding the random access request. In this way, the terminal device waits for a feedback message from the serving network device, thereby avoiding a service interruption caused by a feedback message from the neighboring cell network device.

[0031] Based on the first aspect, in possible implementations, the first scheduling signaling includes first resource configuration information, the third scheduling signaling includes second resource configuration information, the first resource configuration information differs from the second resource configuration information, the third scheduling signaling is carried in DCI, DCI indicates a PRACH resource, and furthermore, the terminal device may first send a random access request to the candidate network device by using the PRACH resource. Based on the difference between the first resource configuration information and the second resource configuration information, the terminal device may send a random access request to the candidate network device. request It may be decided to initiate the initial transmission, thereby enriching the implementation of the solution.

[0032] A second aspect of this application provides a communication method including the following:

[0033] If a serving network device does not receive a feedback message from a neighboring cell network device regarding a random access request from a terminal device, or if a serving network device receives a third feedback message from a neighboring cell network device indicating that the neighboring cell network device does not receive a random access request, the serving network device sends to the terminal device at least one of the following: the first feedback message, the first scheduling signaling, or the first indication information, or the serving network device does not send a feedback message to the terminal device, where ,LaA random access request is used by a terminal device to request access to a target neighboring cell, the target neighboring cell being a neighboring cell of the terminal device's serving cell; a first feedback message indicates that the terminal device's random access failed; a first scheduling signaling is used to schedule the terminal device to resend the random access request; and a first indication information indicates that the terminal device should not resend the random access request to the neighboring cell network device.

[0034] From the above technical solutions, it can be understood that if a serving network device does not receive a feedback message from a neighboring cell network device regarding a random access request from a terminal device, or if a serving network device receives a third feedback message from a neighboring cell network device, the serving network device will either send at least one of the following to the terminal device: the first feedback message, the first scheduling signaling, or the first indication information, or the serving network device will not send a feedback message to the terminal device. The serving network device can monitor feedback messages from neighboring cell network devices regarding random access requests from terminal devices and, based on the feedback messages, may send a corresponding feedback message to the terminal device, or may not send a feedback message. In this way, the terminal device can access random access requestWhile it is not necessary to wait for a response from a neighboring cell network device, it waits for a feedback message from the serving network device regarding the random access request, thereby helping to reduce service interruption time for terminal devices in the serving cell. Therefore, in the technical solution of this application, terminal devices can determine the access status of random access while reducing service interruption time for terminal devices in the serving cell.

[0035] Based on the second aspect, in possible implementations, the method further includes: If a serving network device receives a fourth feedback message from a neighboring cell network device, and the fourth feedback message indicates that the neighboring cell network device has successfully received a random access request from a terminal device, the serving network device sends a second feedback message to the terminal device, or the serving network device does not send a feedback message to the terminal device, wherein the second feedback message indicates that the random access from the terminal device was successful.

[0036] In this implementation, when a serving network device receives a fourth feedback message from a neighboring cell network device, the serving network device either sends a second feedback message to the terminal device, or it does not send a feedback message to the terminal device. In this way, the terminal device determines that its random access was successful. Therefore, the terminal device does not need to wait for a response from a neighboring cell network device regarding the random access, but it does wait for a feedback message from the serving network device regarding the random access request, thereby helping to reduce the service interruption time for the terminal device in the serving cell.

[0037] Based on the second aspect, in a possible implementation, the second feedback message further includes at least one of the following: the target neighbor cell's TA, an identifier assigned to the terminal device by the target neighbor cell, or an uplink resource assigned to the terminal device by the target neighbor cell.

[0038] In this implementation, if the random access of the terminal device is successful, the second feedback message may further include at least one of the above pieces of information. Thus, when the terminal device hands over to a target neighboring cell, the terminal device can communicate with the neighboring cell network device. Furthermore, prior to handing over to a target neighboring cell, the terminal device obtains the information shown above in advance, thereby reducing the service interruption time of the terminal device in the serving cell during the terminal device's cell handover.

[0039] Based on the second aspect, in possible implementations , book The method further includes the following: The serving network device sends a third scheduling signaling to the terminal device, which is used to schedule the terminal device to initiate random access to a target neighboring cell. In this way, the terminal device initiates random access to the neighboring cell network device.

[0040] Based on the second aspect, in possible implementations, the first scheduling signaling includes first resource configuration information, which is used by the terminal device to retransmit random access requests; the third scheduling signaling includes second resource configuration information, which is used by the terminal device to initially send random access requests; and the first resource configuration information is the same as the second resource configuration information. In this implementation, the first and third scheduling signaling include the same resource configuration information, indirectly or implicitly indicating that the terminal device should retransmit random access requests, thereby reducing display overhead.

[0041] Based on the second aspect, in possible implementations, the first scheduling signaling includes second indication information, which indicates that the terminal device should retransmit the random access request. In this implementation, the serving network device explicitly indicates that the terminal device should retransmit the random access request by using the second indication information, and as a result, the terminal device retransmits the random access request.

[0042] Based on the second aspect, in possible implementations, the first scheduling signaling further includes at least one of a third indication information or a power ramping parameter, the third indication information indicating whether a terminal device should increase power to send a random access request, and the power ramping parameter including a power ramping value or a power ramping stage.

[0043] In this implementation, the first scheduling signaling may further include third indication information and / or power ramping parameters. Therefore, the terminal device retransmits random access requests by using appropriate transmit power based on the third indication information and / or power ramping parameters. This helps improve the success rate of random access for the terminal device.

[0044] Based on the second aspect, in possible implementations, the method further includes: The serving network device sends a handover command to a terminal device, which indicates that the terminal device should hand over to a target neighboring cell. In this way, the terminal device initiates random access to the target neighboring cell. Note that this implementation may be used as an alternative, independent solution and is not dependent on the above implementation.

[0045] Based on the second aspect, in possible implementations, the handover command further includes a Target Neighbor Cell TA, which is the TA used by the terminal device to send uplink signals to the Target Neighbor Cell. Thus, prior to handing over to the Target Neighbor Cell, the terminal device acquires the Target Neighbor Cell TA in advance, thereby reducing the service interruption time of the terminal device in the serving cell during the cell handover.

[0046] The 2 Based on the embodiment, in possible implementations, the handover command further includes an identifier for a PUCCH resource used by the terminal device to perform uplink communication with the target neighboring cell. Thus, after handing over to the target neighboring cell, the terminal device may perform uplink transmission with the target neighboring cell by using the PUCCH resource.

[0047] Based on the second aspect, in possible implementations, the method further includes: The serving network device sends a fourth indication to the terminal device, which indicates that the terminal device should not wait for a feedback message from a neighboring cell network device regarding a random access request. In this way, whether the terminal device waits for a feedback message from a neighboring cell network device regarding a random access request is flexibly configured by the neighboring cell network device.

[0048] Based on the second aspect, in possible implementations, the third feedback message specifically indicates that a random access initiated by a terminal device to a target neighboring cell has failed. In this implementation, if the third feedback message indicates that a neighboring cell network device did not receive a random access request, it indicates that a random access initiated by a terminal device to a target neighboring cell has failed.

[0049] Based on the second aspect, in possible implementations, a third scheduling signaling is carried in the DCI, which further indicates that the terminal device receives a feedback message from the serving network device regarding random access requests. In this way, the terminal device awaits feedback messages from the serving network device, thereby avoiding service interruptions caused by feedback messages from neighboring cell network devices.

[0050] A third aspect of this application provides a communication method including the following:

[0051] If a neighboring cell network device does not receive a random access request from a terminal device, the neighboring cell network device sends a third feedback message to the serving network device, or the neighboring cell network device does not send a feedback message to the serving network device, where the third feedback message indicates that the neighboring cell network device did not receive a random access request, which is used by the terminal device to request access to a target neighboring cell, the target neighboring cell being a neighboring cell of the terminal device's serving cell.

[0052] In the above technical solution, if a neighboring cell network device does not receive a random access request from a terminal device, the neighboring cell network device either sends a third feedback message to the serving network device, or it does not send a feedback message to the serving network device. Therefore, the serving network device monitors the feedback message regarding the random access request from the neighboring cell network device, and as a result, the serving network device sends corresponding feedback to the terminal device based on the feedback status. Thus, the terminal device can determine whether the random access was successful based on the feedback status of the serving network device. The terminal device does not need to wait for a response from the neighboring cell network device to the random access request. In this way, the terminal device can determine the access status of random access while reducing the service interruption time for the terminal device in the serving cell.

[0053] Based on the third aspect, in possible implementations, the method further includes: When the neighboring cell network device receives a random access request from a terminal device, the neighboring cell network device sends a fourth feedback message to the serving network device, the fourth feedback message indicating that the neighboring cell network device has successfully received the random access request.

[0054] In this implementation, when a neighboring cell network device receives a random access request, it sends a fourth feedback message to the serving network device, which then feeds back to the terminal device that the random access was successful. The terminal device does not need to wait for a response from the neighboring cell network device to the random access request. In this way, the terminal device can determine the access status of the random access while reducing the service interruption time for the terminal device in the serving cell.

[0055] Based on the third aspect, in possible implementations, the fourth feedback message further includes at least one of the following: the TA of the target neighboring cell, the identifier assigned to the terminal device by the target neighboring cell, or the uplink resource assigned to the terminal device by the target neighboring cell. In this implementation, if the terminal device's random access is successful, the fourth feedback message may further include at least one of the above information. Thus, when the terminal device hands over to the target neighboring cell, the terminal device can communicate with the neighboring cell network device. Furthermore, prior to handing over to the target neighboring cell, the terminal device obtains the information shown above in advance, thereby reducing the service interruption time of the terminal device in the serving cell during the terminal device's cell handover.

[0056] A fourth aspect of this application provides a communication method including the following:

[0057] If a neighboring cell network device does not receive a random access request from a terminal device, the neighboring cell network device sends a third feedback message to the serving network device, or the neighboring cell network device does not send a feedback message to the serving network device, where the third feedback message indicates that the neighboring cell network device did not receive a random access request, which is used by the terminal device to request access to a target neighboring cell, the target neighboring cell being a neighboring cell of the terminal device's serving cell. In response, the serving network device receives a third feedback message from the neighboring cell network device, and the serving network device sends to the terminal device one of the following: the first feedback message, the first scheduling signaling, and the first indication information, or the serving network device does not send a feedback message to the terminal device, where the first feedback message indicates that the terminal device's random access failed, the first scheduling signaling is used to schedule the terminal device to retransmit the random access request, and the first indication information indicates to the neighboring cell network device that the terminal device should not retransmit the random access request.

[0058] Based on the fourth aspect, in possible implementations, the method further includes: When a neighboring cell network device receives a random access request from a terminal device, the neighboring cell network device sends a fourth feedback message to the serving network device, the fourth feedback message indicating that the neighboring cell network device has successfully received the random access request. Correspondingly, the serving network device receives the fourth feedback message from the neighboring cell network device and either sends a second feedback message to the terminal device, or the serving network device does not send a feedback message to the terminal device, the second feedback message indicating that the terminal device's random access was successful.

[0059] Based on the fourth aspect, in a possible implementation, the second feedback message further includes at least one of the following: the target neighbor cell's TA, an identifier assigned to the terminal device by the target neighbor cell, or an uplink resource assigned to the terminal device by the target neighbor cell.

[0060] Based on the fourth aspect, in possible implementations, prior to the method, the method further includes: The serving network device sends a third scheduling signaling to a terminal device, which is used to schedule the terminal device to initiate random access to a target neighboring cell. In this way, the terminal device initiates random access to the neighboring cell network device.

[0061] Based on the fourth aspect, in possible implementations, the first scheduling signaling includes first resource configuration information, which is used by the terminal device to retransmit random access requests; the third scheduling signaling includes second resource configuration information, which is used by the terminal device to initially send random access requests; and the first resource configuration information is the same as the second resource configuration information.

[0062] Based on the fourth aspect, in possible implementations, the first scheduling signaling includes second indication information, which indicates that the terminal device should retransmit the random access request.

[0063] Based on the fourth aspect, in possible implementations, the first scheduling signaling further includes at least one of a third indication information or a power ramping parameter, the third indication information indicating whether a terminal device should increase power to send a random access request, and the power ramping parameter including a power ramping value or a power ramping stage.

[0064] Based on the fourth aspect, in possible implementations, the method further includes: the serving network device sends a fourth indication to the terminal device, which indicates that the terminal device should not wait for feedback messages from neighboring cell network devices regarding random access requests.

[0065] Based on the fourth aspect, in possible implementations, the third feedback message specifically indicates that a random access initiated by the terminal device to the target neighboring cell has failed.

[0066] Based on the fourth aspect, in possible implementations, the third scheduling signaling is carried in the DCI, which further indicates that the terminal device receives feedback messages from the serving network device regarding random access requests.

[0067] A fifth aspect of this application provides a communication method including the following:

[0068] The terminal device sends message A to a neighboring cell network device, where message A includes a preamble and uplink information, the preamble being used by the terminal device to initiate random access to a target neighboring cell, the target neighboring cell being a neighboring cell of the terminal device's serving cell, and the terminal device receives a first feedback message from the serving network device, where the first feedback message indicates that the random access initiated by the terminal device to the target neighboring cell was successful, the first feedback message further indicates the physical uplink control channel resource used by the terminal device to perform uplink communication with the target neighboring cell, or the terminal device receives a second feedback message from the serving network device, where the second feedback message indicates either that the random access initiated by the terminal device to the target neighboring cell was successful, or that the terminal device has successfully fed back the preamble to the target neighboring cell.

[0069] In the above technical solution, the terminal device does not need to wait for a response from a neighboring cell network device for message A, but waits for a feedback message from the serving network device for message A, thereby helping to reduce the service interruption time for the terminal device in the serving cell. Furthermore, if the terminal device receives a first or second feedback message from the serving network device, the terminal device can determine whether the random access of the terminal device was successful. In other words, the terminal device does not need to wait for a response from a serving network device. device Based on the feedback status, it is possible to determine whether the random access was successful. Therefore, in the technical solution of this application, the terminal device can determine the status of random access while reducing the service interruption time of the terminal device in the serving cell.

[0070] Based on the fifth aspect, in possible implementations, the first feedback message includes an identifier for the PUCCH resource. In this implementation, if the random access by the terminal device is successful, the first feedback message may further include an identifier for the PUCCH resource. Thus, after the terminal device has handed over to a target neighboring cell, the terminal device may perform uplink transmissions with the target neighboring cell by using the PUCCH resource.

[0071] Based on the fifth aspect, in a possible implementation, the second feedback message further includes a first scheduling signaling which indicates that the terminal device should retransmit the uplink information in message A, or indicates that the terminal device should retransmit message A.

[0072] In this implementation, if a target neighboring cell successfully receives only the terminal device's preamble, the serving network device may use a first scheduling signaling to indicate that the terminal device should retransmit message A or the uplink information contained in message A. Thus, the neighboring cell network device obtains the uplink information.

[0073] Based on the fifth aspect, in possible implementations, before the terminal device sends message A to the neighboring cell network device, the method further includes: The terminal device receives a second scheduling signaling from the serving network device, which indicates that the terminal device should initiate random access to a target neighboring cell. In this way, the terminal device initiates random access to a target neighboring cell.

[0074] Based on the fifth aspect, in possible implementations, the second scheduling signaling further includes first indication information, which indicates that a terminal device should initiate random access to a target neighbor cell using a first random access scheme, the first random access scheme comprising the terminal device sending message A to the target neighbor cell, message A including a preamble and uplink information. In this implementation, the serving network device further explicitly indicates that a terminal device should initiate random access to a target neighbor cell using a first random access scheme by using the first indication information. In this way, the terminal device initiates random access to a target neighbor cell using a first random access scheme.

[0075] Based on the fifth aspect, in possible implementations, the method further includes: a terminal device receives a handover command from a serving network device, where the handover command indicates that the terminal device should hand over to a target neighboring cell. This helps the terminal device hand over to a target neighboring cell. Note that this implementation may be used as an alternative, independent solution and is not dependent on the above implementation.

[0076] Based on the fifth aspect, in possible implementations, the method further includes: a terminal device determines at least one of an uplink resource, an uplink transmit beam, an uplink transmit power, or a TA of a target neighboring cell, where the uplink resource is used by the terminal device to communicate with a target neighboring cell, the uplink transmit beam is a beam used by the terminal device to perform uplink transmission with a target neighboring cell, the uplink transmit power is the power used by the terminal device to perform uplink transmission with a target neighboring cell, and the TA of a target neighboring cell is a TA used by the terminal device to transmit uplink signals to a target neighboring cell. In this implementation, the terminal device may determine at least one of the above information, and as a result, the terminal device can communicate with neighboring cell network devices.

[0077] Based on the fifth aspect, in possible implementations, the determination of an uplink resource by a terminal device includes: the terminal device using a pre-configured individual PUCCH resource or a pre-configured CG-PUSCH resource as the uplink resource; or the terminal device determining the uplink resource by using a handover command, where the handover command includes the uplink resource; or the terminal device monitoring a third scheduling signaling sent by a neighboring cell network device on a pre-configured time-frequency resource, where the third scheduling signaling indicates the uplink resource. In this implementation, several possible implementations of how a terminal device determines an uplink resource are shown, thereby enriching the implementation of the solution.

[0078] Based on the fifth aspect, in a possible implementation, the determination of uplink transmit power by a terminal device includes: the terminal device determines the path loss between the terminal device and a neighboring cell network device based on a first path loss reference signal, and the terminal device determines the uplink transmit power based on the path loss. This implementation shows a possible implementation in which the terminal device determines the uplink transmit power, thereby facilitating the implementation of the solution.

[0079] Based on the fifth aspect, in possible implementations, the determination of uplink transmit power by a terminal device includes: the terminal device uses the transmit power for sending random access requests by the terminal device as the uplink transmit power. Another implementation is shown in which the terminal device determines the uplink transmit power, and as a result the terminal device can communicate with neighboring cell network devices.

[0080] Based on the fifth aspect, in possible implementations, if the handover command further includes an activated TCI state of the target neighbor cell, the first path loss reference signal is the path loss reference signal associated with the activated TCI state; or if the handover command further includes a deactivated TCI state of the target neighbor cell, the first path loss reference signal is the SSB associated with the random access resource used by the terminal device to send a random access request; or if the handover command further includes a reference signal for the target neighbor cell, the first path loss reference signal is the reference signal for the target neighbor cell. In this implementation, several possible implementations are shown in which the terminal device determines the first path loss reference signal, thereby helping the terminal device determine the uplink transmit power.

[0081] Based on the fifth aspect, in possible implementations, the handover command further includes power control parameters associated with an activated TCI state or a deactivated TCI state, and the terminal device determines the uplink transmit power based on path loss, which includes: The terminal device determines the uplink transmit power based on path loss and the power control parameters. In this implementation, the handover command further carries power control parameters, and the terminal device may determine the uplink transmit power based on path loss and the power control parameters. This helps the terminal device perform uplink transmissions with serving network devices by using appropriate uplink transmit power, thereby improving communication transmit performance.

[0082] Based on the fifth aspect, in possible implementations, the terminal device determining the TA of the target neighboring cell includes the following: If the handover command includes a TA of the target neighbor cell, the terminal device uses the TA in the handover command as the TA of the target neighbor cell; or if the handover command does not include a TA of the target neighbor cell, the terminal device defaults to assuming the TA of the target neighbor cell is equal to 0; or if the handover command does not include a TA of the target neighbor cell, the terminal device uses the TA carried in the first or second feedback message as the TA of the target neighbor cell; or if the handover command includes an uplink timing advance indication and the uplink timing advance indication indicates that the terminal device should determine the TA of the target neighbor cell, the terminal device uses the TA of the target neighbor cell determined by the terminal device as the TA of the target neighbor cell; or if the handover command includes a TAG ID, the terminal device uses the TA associated with the TAG ID as the TA of the target neighbor cell; or if the handover command does not include a TA of the target neighbor cell and the target neighbor cell is the terminal device's current serving cell, the terminal device uses the serving cell's TA as the TA of the target neighbor cell. This implementation demonstrates several possible implementations in which the terminal device determines the TA of the target neighboring cell, thereby helping the terminal device perform uplink transmissions with neighboring cell network devices and improving communication transmission performance.

[0083] Based on the fifth aspect, in possible implementations, the determination of the uplink transmit beam by a terminal device includes: if the handover command includes a TCI state indicated by a neighboring cell network device for the terminal device, the terminal device determines the uplink transmit beam based on the TCI state indicated in the handover command; or, if the TCI state indicated in the handover command is a downlink TCI state, the terminal device determines the uplink transmit beam based on the received beam of the SSB associated with the random access resource used to send the preamble. In this implementation, several possible implementations are shown in which the terminal device determines the uplink transmit beam, thereby helping the terminal device perform uplink transmissions with neighboring cell network devices and improving communication transmission performance.

[0084] A sixth aspect of this application provides a communication method including the following: If the serving network device receives a random access response success message from a neighboring cell network device, it sends a first feedback message to the terminal device, where the first feedback message indicates that the random access initiated by the terminal device to a target neighboring cell was successful, the target neighboring cell being a neighboring cell of the serving cell of the terminal device, and the first feedback message further indicates the PUCCH resources used by the terminal device to perform uplink transmissions with the target neighboring cell; or, if the serving network device receives a random access response fallback message from a neighboring cell network device, it sends a second feedback message to the terminal device, where the second feedback message indicates either that the random access initiated by the terminal device to a target neighboring cell was successful, or that the preamble was successfully fed back to the target neighboring cell.

[0085] In the above technical solution, if the serving network device receives a random access response success message from a neighboring cell network device, the serving network device sends a first feedback message to the terminal device. If the serving network device receives a random access response fallback message from a neighboring cell network device, the serving network device sends a second feedback message to the terminal device. In this way, the terminal device determines that the random access was successful. The serving network device then processes the random access of the terminal device. request It is possible to monitor feedback messages from neighboring cell network devices regarding random access and, based on these feedback messages, understand that a corresponding feedback message can be sent to the terminal device. In this way, the terminal device does not need to wait for a response from neighboring cell network devices regarding random access, but waits for feedback messages from the serving network device regarding random access requests, thereby helping to reduce service interruption time for the terminal device in the serving cell. Thus, in the technical solution of this application, the terminal device can determine the access status of random access while reducing service interruption time for the terminal device in the serving cell.

[0086] Based on the sixth aspect, in possible implementations, the second feedback message further includes a first scheduling signaling, which indicates that the terminal device should retransmit the uplink information in message A, or that the terminal device should retransmit message A, where message A includes a preamble and uplink information. In this implementation, if the target neighboring cell has successfully received only the terminal device's preamble, the serving network device may use the first scheduling signaling to indicate that the terminal device should retransmit message A or the uplink information in message A. Thus, the neighboring cell network device obtains the uplink information.

[0087] Based on the sixth aspect, in possible implementations, the random access response success message includes an identifier for a PUCCH resource set up by a neighboring cell network device for the terminal device.

[0088] Based on the sixth aspect, in possible implementations, the method further includes: The serving network device sends a handover command to a terminal device, which indicates that the terminal device should hand over to a target neighboring cell. In this way, the terminal device initiates random access to the target neighboring cell. Note that this implementation may be used as an alternative, independent solution and is not dependent on the above implementation.

[0089] Based on the sixth aspect, in possible implementations, the handover command further includes a TA of the target neighboring cell, the TA of the target neighboring cell being used by the terminal device to send uplink signals to the target neighboring cell. Thus, prior to handing over to the target neighboring cell, the terminal device acquires the TA of the target neighboring cell in advance, thereby reducing the service interruption time of the terminal device in the serving cell during the cell handover.

[0090] Based on the sixth aspect, in possible implementations, the handover command further includes an identifier for a PUCCH resource used by the terminal device to perform uplink communication with the target neighboring cell. Thus, after handing over to the target neighboring cell, the terminal device may perform uplink transmission with the target neighboring cell by using the PUCCH resource.

[0091] Based on the sixth aspect, in possible implementations, the method further includes: The serving network device sends a second scheduling signaling to a terminal device, which indicates that the terminal device should initiate random access to a target neighboring cell. In this way, the terminal device initiates random access to a target neighboring cell.

[0092] Based on the sixth aspect, in possible implementations, the second scheduling signaling further includes first indication information, which indicates that a terminal device should initiate random access to a target neighboring cell using a first random access scheme, the first random access scheme comprising the terminal device sending message A to the target neighboring cell, message A comprising a preamble and uplink information. In this way, the terminal device initiates random access to the target neighboring cell using the first random access scheme.

[0093] A seventh aspect of this application provides a communication method including the following: If the neighboring cell network device successfully receives message A sent by the terminal device, it sends a random access response success message to the serving network device, where message A includes the terminal device's preamble and uplink information, where the preamble is used by the terminal device to initiate random access to a target neighboring cell, and the target neighboring cell is a neighboring cell of the terminal device's serving cell. Alternatively, if the neighboring cell network device successfully receives only the preamble in message A from the terminal device, it sends a random access response fallback message to the serving network device.

[0094] In the above technical solution, if a neighboring cell network device successfully receives message A sent by a terminal device, the neighboring cell network device sends a random access response success message to the serving network device. If the neighboring cell network device successfully receives only the preamble in message A from the terminal device, the neighboring cell network device sends a random access response fallback message to the serving network device. Therefore, the serving network device monitors feedback messages regarding message A from the neighboring cell network device, and as a result, sends corresponding feedback to the terminal device based on the feedback status. Thus, the terminal device can determine whether the random access was successful based on the feedback status of the serving network device. The terminal device does not need to wait for a response from the neighboring cell network device regarding message A. In this way, the terminal device can determine the access status of random access while reducing the service interruption time for the terminal device in the serving cell.

[0095] Based on the seventh aspect, in possible implementations, the random access response success message includes an identifier for a PUCCH resource set up by the neighbor cell network device for the terminal device. Thus, the neighbor cell network device sets up a PUCCH resource for the terminal device, and after the terminal device has handed over to a target neighbor cell, the terminal device can use the PUCCH resource to perform uplink transmissions with the target neighbor cell.

[0096] Based on the seventh aspect, in possible implementations, the method further includes: A neighboring cell network device receives message A from a terminal device.

[0097] An eighth aspect of this application provides a communication method including the following: If the neighboring cell network device successfully receives message A sent by the terminal device, it sends a random access response success message to the serving network device, where message A includes the terminal device's preamble and uplink information, where the preamble is used by the terminal device to initiate random access to a target neighboring cell, and the target neighboring cell is a neighboring cell of the terminal device's serving cell. Correspondingly, upon receiving the random access response success message from the neighboring cell network device, the serving network device sends a first feedback message to the terminal device, where the first feedback message indicates that the random access initiated by the terminal device to the target neighboring cell was successful, and further indicates the physical uplink control channel resource used by the terminal device to perform uplink transmission with the target neighboring cell, or The neighboring cell network device sends a random access response fallback message to the serving network device if it has successfully received only the preamble in message A from the terminal device. Correspondingly, the serving network device receives the random access response fallback message from the neighboring cell network device and sends a second feedback message to the terminal device, which indicates either that the random access initiated by the terminal device to the target neighboring cell was successful, or that the preamble has been successfully fed back to the target neighboring cell.

[0098] Based on the eighth aspect, in a possible implementation, the random access response success message includes an identifier for a PUCCH resource set up by a neighboring cell network device for the terminal device.

[0099] In a possible implementation based on the eighth aspect, the second feedback message further includes a first scheduling signaling, which indicates that the terminal device should retransmit the uplink information in message A, or indicates that the terminal device should retransmit message A, where message A includes a preamble and uplink information.

[0100] Based on the eighth aspect, in possible implementations, the method further includes: The serving network device sends a handover command to a terminal device, which indicates that the terminal device should hand over to a target neighboring cell. In this way, the terminal device initiates random access to the target neighboring cell. Note that this implementation may be used as an alternative, independent solution and is not dependent on the above implementation.

[0101] Based on the eighth aspect, in a possible implementation, the handover command further includes a TA of the target neighboring cell, the TA of the target neighboring cell being a TA used by a terminal device to send uplink signals to the target neighboring cell.

[0102] Based on the eighth aspect, in possible implementations, the handover command further includes an identifier for a PUCCH resource used by the terminal device to perform uplink communication with a target neighboring cell.

[0103] Based on the eighth aspect, in possible implementations, the method further includes: The serving network device sends a second scheduling signaling to a terminal device, which indicates that the terminal device should initiate random access to a target neighboring cell.

[0104] Based on the eighth aspect, in a possible implementation, the second scheduling signaling further includes first indication information, which indicates that a terminal device should initiate random access to a target neighboring cell using a first random access scheme, the first random access scheme comprising the terminal device sending message A to the target neighboring cell, message A including a preamble and uplink information.

[0105] A ninth aspect of this application provides a communication method including the following:

[0106] The terminal device sends message 3 to the neighboring cell network device, where message 3 is used by the terminal device to initiate random access to a target neighboring cell, the target neighboring cell being a neighboring cell of the terminal device's serving cell, and message 3 includes the identifier of the terminal device; and the terminal device receives message 4 from the serving network device, where message 4 indicates that the random access initiated by the terminal device to the target neighboring cell was successful.

[0107] From the above technical solution, it can be understood that the terminal device does not need to wait for a response from a neighboring cell network device for message 3, but waits for a response from a serving network device for message 3, thereby helping to reduce the service interruption time for the terminal device in the serving cell. Furthermore, the terminal device receives message 4 from the serving network device, where message 4 indicates that the random access initiated by the terminal device to the target neighboring cell was successful. Thus, the terminal device can determine that the random access was successful based on the feedback status of the serving network device. Thus, in the technical solution of this application, the terminal device can determine the access status of a random access while reducing the service interruption time for the terminal device in the serving cell.

[0108] Based on the ninth aspect, in possible implementations, the method further includes: a terminal device sending message 1 to a neighboring cell network device, where message 1 includes a first preamble of the terminal device; and the terminal device receiving message 2 from a neighboring cell network device or a serving network device, where message 2 is a response to message 1 sent by the terminal device to the neighboring cell network device. In this implementation, two possible implementations are shown in which the terminal device receives and sends messages 1 and 2. The implementation in which the terminal device receives message 2 from the serving network device helps prevent the terminal device from waiting for a response from the neighboring cell network device for message 1, thereby reducing the service interruption time for the terminal device in the serving cell.

[0109] Based on the ninth aspect, in possible implementations, the method further includes: The terminal device sends message 1 to a neighboring cell network device, where message 1 includes the terminal device's first preamble; and if the terminal device does not receive message 2 from the serving network device within a predetermined period, the terminal device resends message 1 to the neighboring cell network device, or the terminal device determines a second preamble and sends the second preamble to the neighboring cell network device. In this implementation, if the terminal device does not receive message 2 from the serving network device within a predetermined period, it indicates that the terminal device's random access has failed. The terminal device may continue to initiate random access to the target neighboring cell by using the first preamble, or it may re-select the second preamble and initiate random access to the target neighboring cell. This helps to improve the success rate of random access.

[0110] Based on the ninth aspect, in possible implementations, a terminal device resending message 1 to a neighboring cell network device includes the following:

[0111] The terminal device determines the transmit power used to send message 1 based on pre-configured power ramping parameters, and the terminal device retransmits message 1 to neighboring cell network devices by using the transmit power. In this implementation, the terminal device can increase the transmit power for sending message 1, thereby helping to improve the success rate of random access.

[0112] Based on the ninth aspect, in possible implementations, the method further includes: a terminal device receives a handover command from a serving network device, where the handover command indicates that the terminal device should hand over to a target neighboring cell. This helps the terminal device hand over to a target neighboring cell. Note that this implementation may be used as an alternative, independent solution and is not dependent on the above implementation.

[0113] Based on the ninth aspect, in possible implementations, the method further includes: a terminal device determines at least one of an uplink resource, an uplink transmit beam, an uplink transmit power, or a TA of a target neighboring cell, where the uplink resource is used by the terminal device to communicate with a target neighboring cell, the uplink transmit beam is a beam used by the terminal device to perform uplink transmission with a target neighboring cell, the uplink transmit power is the power used by the terminal device to perform uplink transmission with a target neighboring cell, and the TA of a target neighboring cell is a TA used by the terminal device to transmit uplink signals to a target neighboring cell. In this implementation, the terminal device may determine at least one of the above information, and as a result, the terminal device can communicate with neighboring cell network devices.

[0114] Based on the ninth aspect, in possible implementations, the determination of an uplink resource by a terminal device includes: the terminal device using a pre-configured individual PUCCH resource or a pre-configured CG-PUSCH resource as the uplink resource; or the terminal device determining the uplink resource by using a handover command, where the handover command includes the uplink resource; or the terminal device monitoring a first scheduling signaling sent by a neighboring cell network device on a pre-configured time-frequency resource, where the first scheduling signaling indicates the uplink resource. In this implementation, several possible implementations of how a terminal device determines an uplink resource are shown, thereby enriching the implementation of the solution.

[0115] Based on the ninth aspect, in a possible implementation, the determination of uplink transmit power by a terminal device includes: the terminal device determines the path loss between the terminal device and a neighboring cell network device based on a first path loss reference signal, and the terminal device determines the uplink transmit power based on the path loss. This implementation shows a possible implementation in which the terminal device determines the uplink transmit power, thereby facilitating the implementation of the solution.

[0116] Based on the ninth aspect, in possible implementations, the determination of uplink transmit power by a terminal device includes: the terminal device uses the transmit power for sending random access requests by the terminal device as the uplink transmit power. Another implementation is shown in which the terminal device determines the uplink transmit power, and as a result the terminal device can communicate with neighboring cell network devices.

[0117] Based on the ninth aspect, in possible implementations, if the handover command further includes an activated TCI state of the target neighbor cell, the first path loss reference signal is the path loss reference signal associated with the activated TCI state; or if the handover command further includes a deactivated TCI state of the target neighbor cell, the first path loss reference signal is the SSB associated with the random access resource used by the terminal device to send a random access request; or if the handover command further includes a reference signal for the target neighbor cell, the first path loss reference signal is the reference signal for the target neighbor cell. In this implementation, several possible implementations are shown in which the terminal device determines the first path loss reference signal, thereby helping the terminal device determine the uplink transmit power.

[0118] Based on the ninth aspect, in possible implementations, the handover command further includes power control parameters associated with an activated TCI state or a deactivated TCI state, and the terminal device determines uplink transmit power based on path loss, which includes: The terminal device determines uplink transmit power based on path loss and power control parameters. In this implementation, the handover command further carries power control parameters, and the terminal device may determine uplink transmit power based on path loss and power control parameters. This helps the terminal device perform uplink transmission with the serving network device by using appropriate uplink transmit power, thereby improving communication transmit performance.

[0119] Based on the ninth aspect, in possible implementations, the determination of the TA of a target neighbor cell by a terminal device includes: if the handover command includes the TA of the target neighbor cell, the terminal device uses the TA in the handover command as the TA of the target neighbor cell; or if the handover command does not include the TA of the target neighbor cell, the terminal device defaults to assuming the TA of the target neighbor cell is equal to 0; or if the handover command does not include the TA of the target neighbor cell, the terminal device uses the TA carried in message 2 as the TA of the target neighbor cell; or if the handover command includes an uplink timing advance indication and the uplink timing advance indication indicates that the terminal device should determine the TA of the target neighbor cell, the terminal device uses the TA of the target neighbor cell determined by the terminal device as the TA of the target neighbor cell; or if the handover command includes a timing advance group identifier (T If the AG ID is included, the TA associated with the TAG ID is used as the TA of the target neighbor cell. Alternatively, if the handover command does not include the TA of the target neighbor cell and the target neighbor cell is the terminal device's current serving cell, the terminal device uses the serving cell's TA as the TA of the target neighbor cell. This implementation shows several possible implementations in which the terminal device determines the TA of the target neighbor cell, thereby helping the terminal device perform uplink transmissions with neighbor cell network devices and improving communication transmission performance.

[0120] Based on the ninth aspect, in possible implementations, the determination of the uplink transmit beam by a terminal device includes: if the handover command includes a TCI state indicated by a neighboring cell network device for the terminal device, the terminal device determines the uplink transmit beam based on the TCI state indicated in the handover command; or, if the TCI state indicated in the handover command is a downlink TCI state, the terminal device determines the uplink transmit beam based on the received beam of the SSB associated with the random access resource used to send the preamble. In this implementation, several possible implementations are shown in which the terminal device determines the uplink transmit beam, thereby helping the terminal device perform uplink transmissions with neighboring cell network devices and improving communication transmission performance.

[0121] A tenth aspect of this application provides a communication method including the following:

[0122] The neighboring cell network device receives message 3 from the terminal device, where message 3 is used by the terminal device to initiate random access to a target neighboring cell, the target neighboring cell being a neighboring cell of the terminal device's serving cell, and message 3 includes the identifier of the terminal device; and the neighboring cell network device sends message 4 to the serving network device, where message 4 indicates that the random access initiated by the terminal device to the target neighboring cell was successful.

[0123] From the above technical solution, the neighboring cell network device can understand that it has received message 3 from the terminal device. The neighboring cell network device then sends message 4 to the serving network device, where message 4 indicates that the random access initiated by the terminal device to the target neighboring cell was successful. Thus, the serving network device monitors the feedback message from the neighboring cell network device regarding message 3, and as a result, the serving network device sends corresponding feedback to the terminal device based on the feedback status. Thus, the terminal device can determine whether its random access was successful based on the feedback status of the serving network device. The terminal device does not need to wait for a response from the neighboring cell network device regarding message 3. In this way, the terminal device can determine the access status of the random access while reducing the service interruption time for the terminal device in the serving cell.

[0124] Based on the tenth aspect, in possible implementations, before a neighbor cell network device receives message 3 from a terminal device, the method further includes: the neighbor cell network device receives message 1 from the terminal device, where message 1 includes a first preamble, which is used by the terminal device to initiate random access to a target neighbor cell; and the neighbor cell network device sends message 2 to the terminal device or serving network device, where message 2 is a response to message 1. In this implementation, two possible implementations are shown in which the terminal device receives and sends messages 1 and 2. The neighbor cell network device may respond to message 1 by sending message 2 to the serving network device. In this case, the serving network device may feed back the response to the terminal device. This helps prevent the terminal device from waiting for a response from the neighbor cell network device about message 1, thereby reducing the service interruption time for the terminal device in the serving cell.

[0125] Based on the tenth aspect, in a possible implementation, message 2 further includes an identifier for the target neighboring cell. In this way, when the terminal device sends message 1 to multiple neighboring cells separately in a short period of time, the terminal device determines that message 2 is a response to message 1 sent by the terminal device to the target neighboring cell.

[0126] Based on the tenth aspect, in possible implementations, the method further includes: A neighboring cell network device receives first information from a serving network device, wherein the first information includes at least one of first indication information, an index of a first SSB of a target neighboring cell, an identifier of a terminal device, or a period used to receive message 1, the first indication information indicating that there is one terminal device that initiates random access to the target neighboring cell by using a random access resource associated with the first SSB. In this implementation, the neighboring cell network device receives first information from the serving network device, and as a result, the neighboring cell network device receives message 1 from the terminal device.

[0127] Based on the tenth aspect, in possible implementations, a neighboring cell network device receiving message 1 from a terminal device includes: The neighboring cell network device receives message 1 from the terminal device based on the first information.

[0128] Based on the tenth aspect, in possible implementations, the terminal device identifier is a cell radio network temporary identifier used by the terminal device in a serving cell. (C -RNTI)

[0129] An eleventh aspect of this application provides a communication method including the following:

[0130] The serving network device receives message 4 from the neighboring cell network device, where message 4 indicates that a random access initiated by the terminal device to a target neighboring cell was successful, the target neighboring cell being a neighboring cell of the terminal device's serving cell, and the serving network device sends message 4 to the terminal device.

[0131] In the technical solution described above, the serving network device receives message 4 from the neighboring cell network device and sends message 4 to the terminal device. Therefore, the terminal device does not need to wait for a response from the neighboring cell network device for message 3, but does wait for a response from the serving network device for message 3, thereby reducing the service interruption time for the terminal device in the serving cell. Furthermore, the terminal device receives message 4 from the serving network device, where message 4 indicates that the random access initiated by the terminal device to the target neighboring cell was successful. Therefore, the terminal device can determine that the random access was successful based on the feedback status of the serving network device. Thus, in the technical solution of this application, the terminal device can determine the access status of a random access while reducing the service interruption time for the terminal device in the serving cell.

[0132] Based on the eleventh aspect, in possible implementations, the method further includes: a serving network device receives message 2 from a neighboring cell network device, where message 2 is a response to message 1 sent to the neighboring cell network device by a terminal device, and the serving network device sends message 2 to the terminal device. In this way, the serving network device feeds back the response to message 1 to the terminal device, preventing the terminal device from waiting for a response from the neighboring cell network device for message 1, thereby reducing service interruption time for the terminal device in the serving cell.

[0133] Based on the eleventh aspect, in possible implementations, the method further includes: The serving network device sends first information to a neighboring cell network device, where the first information is used by the neighboring cell network device to receive message 1, and the first information includes at least one of first indication information, the index of a first SSB of the target neighboring cell, the identifier of a terminal device, or a period used to receive message 1, the first indication information indicating that there is one terminal device that initiates random access to the target neighboring cell by using a random access resource associated with the first SSB. In this implementation, the serving network device sends first information to the neighboring cell network device, and as a result, the neighboring cell network device receives message 1 from a terminal device.

[0134] Based on the eleventh aspect, in possible implementations, the method further includes: The serving network device sends a handover command to a terminal device, which indicates that the terminal device should hand over to a target neighboring cell. In this way, the terminal device initiates random access to the target neighboring cell. Note that this implementation may be used as an alternative, independent solution and is not dependent on the above implementation.

[0135] Based on the 11th aspect, in a possible implementation, the handover command further includes a TA of the target neighboring cell, the TA of the target neighboring cell being a TA used by a terminal device to send uplink signals to the target neighboring cell.

[0136] Based on the eleventh aspect, in possible implementations, the handover command further includes an identifier for a PUCCH resource used by the terminal device to perform uplink communication with a target neighboring cell.

[0137] According to a twelfth aspect of this application, a communication method is provided, which includes the following:

[0138] The neighboring cell network device receives message 3 from the terminal device, where message 3 is used by the terminal device to initiate random access to a target neighboring cell, the target neighboring cell being a neighboring cell of the terminal device's serving cell, message 3 containing the identifier of the terminal device, and the neighboring cell network device sends message 4 to the serving network device, where message 4 indicates that the random access initiated by the terminal device to the target neighboring cell was successful. Correspondingly, the serving network device receives message 4 from the neighboring cell network device, and the neighboring cell network device sends message 4 to the terminal device.

[0139] Based on the twelfth aspect, in possible implementations, the method further includes: a neighboring cell network device sends message 2 to a serving network device, where message 2 is a response to message 1; the serving network device receives message 2 from the neighboring cell network device, where message 2 is a response to message 1 sent to the neighboring cell network device by a terminal device; and the serving network device sends message 2 to the terminal device.

[0140] Based on the twelfth aspect, in possible implementations, the method further includes: The serving network device sends first information to a neighboring cell network device, where the first information is used by the neighboring cell network device to receive message 1, and the first information includes at least one of first indication information, the index of the first SSB of the target neighboring cell, the identifier of a terminal device, or a period used to receive message 1, the first indication information indicating that there is one terminal device that initiates random access to the target neighboring cell by using a random access resource associated with the first SSB. Correspondingly, the neighboring cell network device receives first information from the serving network device.

[0141] Based on the twelfth aspect, in possible implementations, the method further includes: The serving network device sends a handover command to a terminal device, which indicates that the terminal device should hand over to a target neighboring cell.

[0142] Based on the 12th aspect, in a possible implementation, the handover command further includes a TA of the target neighboring cell, the TA of the target neighboring cell being a TA used by a terminal device to send uplink signals to the target neighboring cell.

[0143] Based on the 12th aspect, in possible implementations, the handover command further includes an identifier for a PUCCH resource used by the terminal device to perform uplink communication with a target neighboring cell.

[0144] Based on the 12th aspect, in possible implementations, the identifier of the terminal device is the C-RNTI used by the terminal device in the serving cell.

[0145] A thirteenth aspect of this application is a communication device, The present invention provides a communication device including a transceiver module configured to send a random access request to a neighboring cell network device, the random access request being used to initiate random access to a target neighboring cell, the target neighboring cell being a neighboring cell of the communication device's serving cell; and to retransmit the random access request to the neighboring cell network device if the communication device does not receive a feedback message from the serving network device about the random access request, or if the communication device receives at least one of a first feedback message or a first scheduling signaling from the serving network device, the first feedback message indicating that the communication device's random access failed, and the first scheduling signaling being used to schedule the communication device to retransmit the random access request.

[0146] In a possible implementation based on the 13th aspect, the communication device further includes a processing module. The processing module is configured to determine that the communication device's random access was successful when the communication device receives a second feedback message from the serving network device, the second feedback message indicating that the neighboring cell network device successfully received the random access request.

[0147] In a possible implementation based on the 13th aspect, the communication device further includes a processing module. The processing module is configured to determine that the communication device's random access was successful when the communication device receives first indication information from a serving network device, where the first indication information indicates that the communication device should not retransmit the random access request to a neighboring cell network device.

[0148] In a possible implementation based on the 13th aspect, the second feedback message further includes at least one of the following: the TA of the target neighboring cell, an identifier assigned to the communication device by the target neighboring cell, or an uplink resource assigned to the communication device by the target neighboring cell.

[0149] Based on the 13th aspect, in possible implementations, the transceiver module is: It is specifically configured to retransmit random access requests to neighboring cell network devices based on a preset number of retransmissions and / or preset power ramping parameters.

[0150] Based on the 13th aspect, in possible implementations, the first feedback message or first scheduling signaling further includes power ramping parameters, and the transceiver module is specifically configured to retransmit random access requests to neighboring cell network devices based on the power ramping parameters.

[0151] Based on the 13th aspect, in possible implementations, the transceiver module is: It is further configured to receive a handover command from a serving network device, where the handover command indicates that the communication device should hand over to a target neighboring cell.

[0152] In a possible implementation based on the 13th aspect, the communication device further includes a processing module. The processing module is configured to determine at least one of the following: uplink resource, uplink transmit beam, uplink transmit power, or TA of a target neighboring cell, where uplink resource is used by the communication device to perform uplink transmission with a target neighboring cell; uplink transmit beam is a beam used by the communication device to perform uplink transmission with a target neighboring cell; uplink transmit power is power used by the communication device to perform uplink transmission with a target neighboring cell; and TA of a target neighboring cell is a TA used by the communication device to send an uplink signal to a target neighboring cell.

[0153] Based on the 13th aspect, in possible implementations, the processing module is: Using pre-configured individual PUCCH resources or pre-configured CG-PUSCH resources as uplink resources, Determining uplink resources by using a handover command, where the handover command includes determining uplink resources, or The monitoring involves monitoring a second scheduling signaling transmitted by a neighboring cell network device on a pre-configured time-frequency resource, the second scheduling signaling being specifically configured to indicate an uplink resource.

[0154] Based on the 13th aspect, in possible implementations, the processing module is: Determining the first path loss reference signal, Based on the first path loss reference signal, the path loss between the neighboring cell network device and the communication device is determined, It is specifically configured to determine the uplink transmit power based on path loss.

[0155] Based on the 13th aspect, in possible implementations, the processing module is: The communication device is specifically configured to use the transmit power for sending random access requests as uplink transmit power.

[0156] Based on the 13th aspect, in possible implementations, if the handover command further includes an activated TCI state of the target neighbor cell, the first path loss reference signal is a path loss reference signal associated with the activated TCI state; or if the handover command further includes a deactivated TCI state of the target neighbor cell, the first path loss reference signal is an SSB associated with a random access resource used by the communication device to send a random access request; or if the handover command further includes a reference signal for the target neighbor cell, the first path loss reference signal is a reference signal for the target neighbor cell.

[0157] Based on the 13th aspect, in possible implementations, the handover command further includes power control parameters associated with the activated TCI state of the target neighbor cell, or power control parameters associated with the deactivated TCI state of the target neighbor cell, and the processing module, It is specifically configured to determine the uplink transmit power based on path loss and power control parameters.

[0158] Based on the 13th aspect, in possible implementations, the processing module is: If the handover command includes a TA of the target neighboring cell, use the TA in the handover command as the TA of the target neighboring cell, or If the handover command does not include the target neighbor cell's TA, by default, the target neighbor cell's TA is assumed to be equal to 0, or If the handover command does not include the TA of the target neighboring cell, use the TA carried in the second feedback message as the TA of the target neighboring cell, or If the handover command includes an uplink timing advance indication, and the uplink timing advance indication indicates that the communication device should determine the TA of the target neighbor cell, then use the TA of the target neighbor cell determined by the communication device as the TA of the target neighbor cell, or If the handover command includes a TAG ID, use the TA associated with the TAG ID as the TA of the target neighboring cell, or If the handover command does not include the TA of the target neighboring cell, and the target neighboring cell is the current serving cell of the communication device, the system is specifically configured to use the serving cell's TA as the TA of the target neighboring cell.

[0159] Based on the 13th aspect, in possible implementations, the processing module is: If the handover command includes a TCI state indicated by a neighboring cell network device for the communication device, the uplink transmit beam is determined based on the TCI state indicated in the handover command, or If the TCI state indicated in the handover command is a downlink TCI state, the system is specifically configured to determine the uplink transmit beam based on the SSB receive beam associated with the random access resource used to send the random access request.

[0160] Based on the 13th aspect, in possible implementations, the first scheduling signaling includes second indication information, which indicates that the communication device should retransmit the random access request.

[0161] Based on the 13th aspect, in possible implementations, the first scheduling signaling further includes at least one of a third indication information or a power ramping parameter, the third indication information indicating whether the communication device should increase power to send a random access request, and the power ramping parameter including a power ramping value or a power ramping stage.

[0162] Based on the 13th aspect, in possible implementations, the transceiver module is: The communication device is further configured to receive a fourth indication from a serving network device, the fourth indication indicating that the communication device should not wait for a feedback message from a neighboring cell network device regarding a random access request, and to continue communicating with the serving network device without waiting for a feedback message from a neighboring cell network device regarding a random access request.

[0163] Based on the 13th aspect, in possible implementations, the transceiver module is: The device is further configured to receive a third scheduling signaling from a serving network device, which is used to schedule the communication device to initiate random access to a target neighboring cell.

[0164] Based on the 13th aspect, in a possible implementation, the third scheduling signaling is carried in the DCI, which indicates that the communication device sends a random access request to a neighboring cell network device, and the DCI further indicates that the communication device receives a feedback message from the serving network device regarding the random access request.

[0165] A fourteenth aspect of this application provides a communication device including the following: The transceiver module is configured to send at least one of the following to a terminal device, or to skip sending a feedback message to a terminal device, if the communication device does not receive a feedback message from a neighboring cell network device, or if the communication device receives a third feedback message from a neighboring cell network device, and the third feedback message indicates that the neighboring cell network device does not receive a random access request. La A random access request is used by a terminal device to request access to a target neighboring cell, the target neighboring cell being a neighboring cell of the terminal device's serving cell; a first feedback message indicates that the terminal device's random access failed; a first scheduling signaling is used to schedule the terminal device to resend the random access request; and a first indication message indicates to neighboring cell network devices not to resend the random access request.

[0166] Based on the 14th aspect, in possible implementations, the transceiver module is: The communication device is further configured to either send a second feedback message to the terminal device or skip sending a feedback message to the terminal device if it receives a fourth feedback message from a neighboring cell network device, and the fourth feedback message indicates that the neighboring cell network device has successfully received the terminal device's random access request. The second feedback message indicates that the terminal device's random access was successful.

[0167] Based on the 14th aspect, in a possible implementation, the second feedback message further includes at least one of the following: the target neighbor cell's TA, an identifier assigned to the terminal device by the target neighbor cell, or an uplink resource assigned to the terminal device by the target neighbor cell.

[0168] Based on the 14th aspect, in a possible implementation, the transceiver module is further configured to send a third scheduling signaling to a terminal device, which is used to schedule the terminal device to initiate random access to a target neighboring cell.

[0169] Based on the 14th aspect, in possible implementations, a first scheduling signaling includes first resource configuration information, which is used by the terminal device to retransmit random access requests; a third scheduling signaling includes second resource configuration information, which is used by the terminal device to initially send random access requests; and the first resource configuration information is the same as the second resource configuration information.

[0170] Based on the 14th aspect, in possible implementations, the first scheduling signaling includes second indication information, which indicates that the terminal device should retransmit the random access request.

[0171] Based on the 14th aspect, in possible implementations, the first scheduling signaling further includes at least one of a third indication information or a power ramping parameter, the third indication information indicating whether a terminal device should increase power to send a random access request, and the power ramping parameter including a power ramping value or a power ramping stage.

[0172] Based on the 14th aspect, in possible implementations, the transceiver module is further configured to send a fourth indication to a terminal device, where the fourth indication indicates that the terminal device should not wait for feedback messages from neighboring cell network devices regarding random access requests.

[0173] Based on the 14th aspect, in a possible implementation, the third feedback message specifically indicates that a random access initiated by the terminal device to the target neighboring cell has failed.

[0174] Based on the 14th aspect, in a possible implementation, a third scheduling signaling is carried in the DCI, which indicates that a terminal device should send a random access request to a neighboring cell network device, and the DCI further indicates that the terminal device should receive a feedback message from a communication device regarding the random access request.

[0175] A 15th aspect of this application is a communication device, The communication device includes a transceiver module configured to either send a third feedback message to a serving network device or skip sending a feedback message to a serving network device if the communication device does not receive a random access request from a terminal device, wherein A third feedback message indicates that the communication device has not received a random access request, which is used by a terminal device to request access to a target neighboring cell, and the target neighboring cell is a neighboring cell of the terminal device's serving cell, provided by the communication device.

[0176] Based on the 15th aspect, in possible implementations, the transceiver module is: The communication device is further configured to send a fourth feedback message to the serving network device when it receives a random access request from a terminal device, the fourth feedback message indicating that the communication device has successfully received the random access request.

[0177] In a possible implementation based on the 15th aspect, the fourth feedback message further includes at least one of the following: the target neighbor cell's TA, an identifier assigned to the terminal device by the target neighbor cell, or an uplink resource assigned to the terminal device by the target neighbor cell.

[0178] A sixteenth aspect of this application is a communication device, The present invention provides a communication device including a transceiver module configured to send message A to a neighboring cell network device, message A comprising a preamble and uplink information, the preamble being used by the communication device to initiate random access to a target neighboring cell, the target neighboring cell being a neighboring cell of the communication device's serving cell; and receive a first feedback message from a serving network device, the first feedback message indicating that the random access initiated by the communication device to the target neighboring cell was successful, and further indicating a physical uplink control channel resource used by the communication device to perform uplink communication with the target neighboring cell; or receive a second feedback message from a serving network device, the second feedback message indicating either only that the random access initiated by the communication device to the target neighboring cell was successful, or indicating that the communication device has successfully fed back the preamble to the target neighboring cell.

[0179] Based on the 16th aspect, in possible implementations, the first feedback message includes an identifier for the PUCCH resource.

[0180] In a possible implementation based on the 16th aspect, the second feedback message further includes a first scheduling signaling which indicates that the communication device should retransmit the uplink information in message A, or that the communication device should retransmit message A.

[0181] Based on the 16th aspect, in a possible implementation, the transceiver module is further configured to receive a second scheduling signaling from a serving network device, where the second scheduling signaling indicates that the communication device should initiate random access to a target neighboring cell.

[0182] Based on the 16th aspect, in a possible implementation, the second scheduling signaling further includes first indication information, which indicates that the communication device should initiate random access to a target neighboring cell using a first random access scheme, the first random access scheme comprising the communication device sending message A to the target neighboring cell, message A including a preamble and uplink information.

[0183] Based on the 16th aspect, in possible implementations, the transceiver module is further configured to receive a handover command from a serving network device, where the handover command indicates that the communication device should hand over to a target neighboring cell.

[0184] In a possible implementation based on the 16th aspect, the communication device further includes a processing module. The processing module is configured to determine at least one of the following: uplink resource, uplink transmit beam, uplink transmit power, or target neighbor cell TA, where uplink resource is used by the communication device to communicate with the target neighbor cell; uplink transmit beam is a beam used by the communication device to perform uplink transmission with the target neighbor cell; uplink transmit power is power used by the communication device to perform uplink transmission with the target neighbor cell; and target neighbor cell TA is a TA used by the communication device to transmit uplink signals to the target neighbor cell.

[0185] Based on the 16th aspect, in possible implementations, the processing module is: The uplink resource is determined by using a pre-configured individual PUCCH resource or a pre-configured CG-PUSCH resource as the uplink resource, or by using a handover command, wherein the handover command is specifically configured to determine the uplink resource, or to monitor a third scheduling signaling sent by a neighboring cell network device on a pre-configured time-frequency resource, wherein the third scheduling signaling indicates the uplink resource.

[0186] Based on the 16th aspect, in possible implementations, the processing module is: Based on the first path loss reference signal, the path loss between the neighboring cell network device and the communication device is determined, It is specifically configured to determine the uplink transmit power based on path loss.

[0187] Based on the 16th aspect, in possible implementations, the processing module is: The communication device is specifically configured to use the transmit power for sending random access requests as uplink transmit power.

[0188] Based on the 16th aspect, in possible implementations, if the handover command further includes an activated TCI state of the target neighbor cell, the first path loss reference signal is a path loss reference signal associated with the activated TCI state; or if the handover command further includes a deactivated TCI state of the target neighbor cell, the first path loss reference signal is an SSB associated with a random access resource used by the communication device to send a random access request; or if the handover command further includes a reference signal for the target neighbor cell, the first path loss reference signal is a reference signal for the target neighbor cell.

[0189] In a possible implementation based on the 16th aspect, the handover command further includes power control parameters associated with an activated TCI state or power control parameters associated with a deactivated TCI state. The processing module is, It is specifically configured to determine the uplink transmit power based on path loss and power control parameters.

[0190] Based on the 16th aspect, in possible implementations, the processing module is: If the handover command includes a TA of the target neighboring cell, use the TA in the handover command as the TA of the target neighboring cell, or If the handover command does not include the target neighbor cell's TA, by default, the target neighbor cell's TA is assumed to be equal to 0, or If the handover command does not include the TA of the target neighboring cell, use the TA carried in the first or second feedback message as the TA of the target neighboring cell, or If the handover command includes an uplink timing advance indication, and the uplink timing advance indication indicates that the communication device should determine the TA of the target neighbor cell, then use the TA of the target neighbor cell determined by the communication device as the TA of the target neighbor cell, or If the handover command includes a TAG ID, use the TA associated with the TAG ID as the TA of the target neighboring cell, or If the handover command does not include the TA of the target neighboring cell, and the target neighboring cell is the current serving cell of the communication device, the system is specifically configured to use the serving cell's TA as the TA of the target neighboring cell.

[0191] Based on the 16th aspect, in possible implementations, the processing module is: If the handover command includes a TCI state indicated by a neighboring cell network device for the communication device, the uplink transmit beam is determined based on the TCI state indicated in the handover command, or If the TCI state indicated in the handover command is a downlink TCI state, the system is specifically configured to determine the uplink transmit beam based on the SSB receive beam associated with the random access resource used to send the preamble.

[0192] A 17th aspect of this application is a communication device, The present invention provides a communication device including a transceiver module, configured to send a first feedback message to a terminal device when the communication device receives a random access response success message from a neighboring cell network device, the first feedback message indicating that a random access initiated by the terminal device to a target neighboring cell was successful, the target neighboring cell being a neighboring cell of the terminal device's serving cell, and the first feedback message further indicating the PUCCH resources used by the terminal device to perform an uplink transmission with the target neighboring cell; or, when the communication device receives a random access response fallback message from a neighboring cell network device, the second feedback message indicating either that a random access initiated by the terminal device to a target neighboring cell was successful, or that the preamble was successfully fed back to the target neighboring cell.

[0193] In a possible implementation based on the 17th aspect, the second feedback message further includes a first scheduling signaling, which indicates that the terminal device should retransmit the uplink information in message A, or indicates that the terminal device should retransmit message A, where message A includes a preamble and uplink information.

[0194] Based on the 17th aspect, in possible implementations, the random access response success message includes an identifier for a PUCCH resource set up by a neighboring cell network device for the terminal device.

[0195] Based on the 17th aspect, in possible implementations, the transceiver module is further configured to send a handover command to a terminal device, which indicates that the terminal device should hand over to a target neighboring cell.

[0196] Based on the 17th aspect, in possible implementations, the handover command further includes a TA of the target neighboring cell, the TA of the target neighboring cell being a TA used by a terminal device to send uplink signals to the target neighboring cell.

[0197] Based on the 17th aspect, in possible implementations, the handover command further includes an identifier for a PUCCH resource used by the terminal device to perform uplink communication with a target neighboring cell.

[0198] Based on the 17th aspect, in possible implementations, the transceiver module is: It is further configured to send a second scheduling signaling to the terminal device, which indicates that the terminal device should initiate random access to a target neighboring cell.

[0199] Based on the 17th aspect, in a possible implementation, the second scheduling signaling further includes first indication information, which indicates that a terminal device should initiate random access to a target neighboring cell using a first random access scheme, the first random access scheme comprising the terminal device sending message A to the target neighboring cell, message A comprising a preamble and uplink information.

[0200] The eighteenth aspect of this application is a communication device, The present invention provides a communication device, including a transceiver module, configured to send a random access response success message to a serving network device when the communication device successfully receives message A sent by a terminal device, wherein message A includes the terminal device's preamble and uplink information, the preamble being used by the terminal device to initiate random access to a target neighbor cell, the target neighbor cell being a neighbor cell of the terminal device's serving cell, or to send a random access response fallback message to the serving network device when the communication device successfully receives only the preamble in message A from the terminal device.

[0201] In a possible implementation based on the 18th aspect, the random access response success message includes an identifier for a PUCCH resource set up by the communication device for the terminal device.

[0202] Based on the 18th aspect, in a possible implementation, the transceiver module is configured to receive message A from a terminal device.

[0203] A 19th aspect of this application is a communication device, A communication device including a transceiver module configured to send a message 3 to a neighboring cell network device, where message 3 is used by the communication device to initiate random access to a target neighboring cell, where the target neighboring cell is a neighboring cell of the communication device's serving cell, and message 3 includes an identifier of the communication device; and to receive a message 4 from a serving network device, where message 4 indicates that the random access initiated by the communication device to the target neighboring cell was successful.

[0204] Based on the 19th aspect, in possible implementations, the transceiver module is: The device is further configured to send a message 1 to a neighboring cell network device, the message 1 including a first preamble of the communication device, and to receive a message 2 from a neighboring cell network device or a serving network device, the message 2 being a response to the message 1 sent to the neighboring cell network device by the communication device.

[0205] In a possible implementation based on the 19th aspect, the transceiver module is further configured to send message 1 to a neighboring cell network device, which includes a first preamble of the communication device, and, if the communication device does not receive message 2 from the serving network device within a predetermined period, to retransmit message 1 to the neighboring cell network device, or to determine a second preamble and send the second preamble to the neighboring cell network device.

[0206] In a possible implementation based on the 19th aspect, the communication device further includes a processing module. The processing module is configured to determine the transmit power used to send message 1 based on pre-configured power ramping parameters. The transceiver module is specifically configured to retransmit message 1 to neighboring cell network devices by using its transmit power.

[0207] Based on the 19th aspect, in possible implementations, the transceiver module is further configured to receive a handover command from a serving network device, where the handover command indicates that the communication device should hand over to a target neighboring cell.

[0208] In a possible implementation based on the 19th aspect, the communication device further includes a processing module. The processing module is configured to determine at least one of the following: uplink resource, uplink transmit beam, uplink transmit power, or target neighbor cell TA, where uplink resource is used by the communication device to communicate with the target neighbor cell; uplink transmit beam is a beam used by the communication device to perform uplink transmission with the target neighbor cell; uplink transmit power is power used by the communication device to perform uplink transmission with the target neighbor cell; and target neighbor cell TA is a TA used by the communication device to transmit uplink signals to the target neighbor cell.

[0209] Based on the 19th aspect, in possible implementations, the processing module is: The uplink resource is determined by using a pre-configured individual PUCCH resource or a pre-configured CG-PUSCH resource as the uplink resource, or by using a handover command, wherein the handover command is specifically configured to determine the uplink resource, or to monitor a first scheduling signaling sent by a neighboring cell network device on a pre-configured time-frequency resource, wherein the first scheduling signaling indicates the uplink resource.

[0210] Based on the 19th aspect, in possible implementations, the processing module is: Based on the first path loss reference signal, the path loss between the neighboring cell network device and the communication device is determined, It is specifically configured to determine the uplink transmit power based on path loss.

[0211] Based on the 19th aspect, in possible implementations, the processing module is: The communication device is specifically configured to use the transmit power for sending random access requests as uplink transmit power.

[0212] Based on the 19th aspect, in possible implementations, if the handover command further includes an activated TCI state of the target neighbor cell, the first path loss reference signal is a path loss reference signal associated with the activated TCI state; or if the handover command further includes a deactivated TCI state of the target neighbor cell, the first path loss reference signal is an SSB associated with a random access resource used by the communication device to send a random access request; or if the handover command further includes a reference signal for the target neighbor cell, the first path loss reference signal is a reference signal for the target neighbor cell.

[0213] Based on the 19th aspect, in possible implementations, the handover command further includes power control parameters associated with an activated TCI state or a power control parameter associated with a deactivated TCI state, and the processing module, It is specifically configured to determine the uplink transmit power based on path loss and power control parameters.

[0214] Based on the 19th aspect, in possible implementations, the processing module is: The system is specifically configured to: use the TA in the handover command as the TA of the target neighbor cell if the handover command includes the TA of the target neighbor cell; or, if the handover command does not include the TA of the target neighbor cell, to assume by default that the TA of the target neighbor cell is equal to 0; or, if the handover command does not include the TA of the target neighbor cell, to use the TA carried in message 2 as the TA of the target neighbor cell; or, if the handover command includes an uplink timing advance indication and the uplink timing advance indication indicates that the communication device should determine the TA of the target neighbor cell, to use the TA of the target neighbor cell determined by the communication device as the TA of the target neighbor cell; or, if the handover command includes a TAG ID, to use the TA associated with the TAG ID as the TA of the target neighbor cell; or, if the handover command does not include the TA of the target neighbor cell and the target neighbor cell is the communication device's current serving cell, to use the TA of the serving cell as the TA of the target neighbor cell.

[0215] Based on the 19th aspect, in possible implementations, the processing module is: The system is specifically configured to determine the uplink transmit beam based on the TCI state indicated in the handover command if the handover command includes a TCI state indicated by a neighboring cell network device for the communication device, or, if the TCI state indicated in the handover command is a downlink TCI state, to determine the uplink transmit beam based on the SSB receive beam associated with the random access resource used to send the preamble.

[0216] A 20th aspect of this application is a communication device, The present invention provides a communication device including a transceiver module configured to receive a message 3 from a terminal device, the message 3 being used by the terminal device to initiate random access to a target neighboring cell, the target neighboring cell being a neighboring cell of the terminal device's serving cell, and the message 3 including an identifier of the terminal device; and to send a message 4 to a serving network device, the message 4 indicating that the random access initiated by the terminal device to the target neighboring cell was successful.

[0217] Based on the 20th aspect, in possible implementations, the transceiver module is: The system is further configured to receive message 1 from a terminal device, message 1 including a first preamble which is used by the terminal device to initiate random access to a target neighboring cell, and to send message 2 to the terminal device or a serving network device, message 2 being a response to message 1.

[0218] Based on the 20th aspect, in possible implementations, the transceiver module is: The device is further configured to receive first information from a serving network device, the first information comprising at least one of first indication information, the index of the first SSB of the target neighboring cell, the identifier of a terminal device, or a period used to receive message 1, wherein the first indication information indicates that there is one terminal device that initiates random access to the target neighboring cell by using a random access resource associated with the first SSB.

[0219] In a possible implementation based on the 20th aspect, the transceiver module is specifically configured to receive message 1 from a terminal device based on the first information.

[0220] Based on the 20th aspect, in possible implementations, the identifier of the terminal device is the C-RNTI used by the terminal device in the serving cell.

[0221] A 21st aspect of this application is a communication device, The present invention provides a communication device including a transceiver module configured to receive and send message 4 to a terminal device, wherein message 4 is a neighboring cell of the terminal device's serving cell, and the device receives message 4 from a neighboring cell network device, where message 4 indicates that a random access initiated by a terminal device to a target neighboring cell was successful, and the target neighboring cell is a neighboring cell of the terminal device's serving cell.

[0222] Based on the 21st aspect, in possible implementations, the transceiver module is: The system is further configured to receive message 2 from a neighboring cell network device, where message 2 is a response to message 1 sent to the neighboring cell network device by the terminal device, and to send message 2 to the terminal device.

[0223] Based on the 21st aspect, in possible implementations, the transceiver module is: The system is further configured to send first information to neighboring cell network devices, where the first information is used by the neighboring cell network devices to receive message 1, and the first information includes at least one of first indication information, the index of the first SSB of the target neighboring cell, the identifier of a terminal device, or a period used to receive message 1, wherein the first indication information indicates that there is one terminal device that initiates random access to the target neighboring cell by using a random access resource associated with the first SSB.

[0224] Based on the 21st aspect, in possible implementations, the transceiver module is: The system is further configured to send a handover command to the terminal device, which indicates that the terminal device should hand over to a target neighboring cell. In this way, the terminal device initiates random access to the target neighboring cell.

[0225] Based on the 21st aspect, in a possible implementation, the handover command further includes a TA of the target neighboring cell, the TA of the target neighboring cell being a TA used by a terminal device to send uplink signals to the target neighboring cell.

[0226] Based on the 21st aspect, in possible implementations, the handover command further includes an identifier for a PUCCH resource used by the terminal device to perform uplink communication with a target neighboring cell.

[0227] A 22nd aspect of this application provides a communication device, the communication device including a processor and memory, the memory storing computer programs or computer instructions, and the processor being configured to call and run the computer programs or computer instructions stored in memory, the processor implementing any one of the implementations of the first through 12th aspects.

[0228] Optionally, the communication device further includes transceivers, and the processor is configured to control the transceivers to receive or transmit signals.

[0229] A 23rd aspect of this application provides a communication device, the communication device including a processor, the processor configured to call computer programs or computer instructions in memory, and as a result the processor implements any one of the implementations of the first through 12th aspects.

[0230] Optionally, the communication device further includes transceivers, and the processor is configured to control the transceivers to receive or transmit signals.

[0231] A 24th aspect of this application provides a communication device, the communication device including a processor, the processor being configured to implement any one of the implementations of the first to 12th aspects.

[0232] A 25th aspect of this application provides a computer program product including instructions. When the computer program product is run on a computer, the computer is enabled to implement any one of the implementations of the first through 12th aspects.

[0233] A 26th aspect of this application provides a computer-readable storage medium containing computer instructions. When the instructions are executed on a computer, the computer is enabled to implement any one of the implementations of the first through 12th aspects.

[0234] A 27th aspect of this application provides a chip device including a processor, the processor configured to call a computer program or computer instruction in memory, and as a result the processor implements any one of the implementations of the first through 12th aspects.

[0235] Optionally, the processor is coupled to memory via an interface.

[0236] A 28th aspect of this application provides a communication system. The communication system includes a communication device shown in the 13th aspect, a communication device shown in the 14th aspect, and a communication device shown in the 15th aspect, or the communication system includes a communication device shown in the 16th aspect, a communication device shown in the 17th aspect, and a communication device shown in the 18th aspect, or the communication system includes a communication device shown in the 19th aspect, a communication device shown in the 20th aspect, and a communication device shown in the 21st aspect.

[0237] From the technical solutions described above, it can be understood that the embodiments of this application have the following advantages.

[0238] From the above technical solutions, it can be understood that a terminal device sends a random access request to a neighboring cell network device. The random access request is used to initiate random access to a target neighboring cell, which is a neighboring cell of the terminal device's serving cell. The terminal device resends the random access request to the neighboring cell network device if it does not receive a feedback message from the serving network device about the random access request, or if it receives at least one of a first feedback message or a first scheduling signal from the serving network device, where the first feedback message indicates that the terminal device's random access failed, and the first scheduling signal indicates that the terminal device should resend the random access request. After the terminal device has sent a random access request to the neighboring cell network device, it can be understood that it may wait for a feedback message from the serving network device about the random access request. The terminal device does not need to wait for a response from the neighboring cell network device about the random access request, but it does wait for a feedback message from the serving network device about the random access request, and it can be understood that this helps reduce the service interruption time for the terminal device in the serving cell. Furthermore, if the terminal device does not receive a feedback message from the serving network device regarding the random access request, or if the terminal device receives at least one of the first feedback message or the first scheduling signaling from the serving network device, the terminal device may retransmit the random access request to the neighboring cell network device. In this way, the terminal device may determine whether the random access was successful based on the feedback status of the serving network device.Therefore, the technical solution of this application enables a terminal device to determine the access status of random access while reducing the service interruption time of the terminal device in the serving cell. [Brief explanation of the drawing]

[0239] [Figure 1] This is a diagram of a communication system according to one embodiment of the present application. [Figure 2] Another diagram of a communication system according to one embodiment of this application. [Figure 3] This is a diagram illustrating a scenario to which a communication method according to one embodiment of this application can be applied. [Figure 4] This is a diagram of a contention-based random access procedure according to one embodiment of this application. [Figure 5] This is a diagram of a contention-free random access procedure according to one embodiment of this application. [Figure 6] This is a diagram of one embodiment of a communication method according to one embodiment of the present application. [Figure 7] This is a diagram illustrating a scenario of a communication method according to one embodiment of this application. [Figure 8] This is a diagram of another embodiment of the communication method according to the embodiments of this application. [Figure 9] This is a diagram of yet another embodiment of a communication method according to one embodiment of the present application. [Figure 10] This is a diagram showing the structure of a communication device according to one embodiment of this application. [Figure 11] This is a diagram showing another structure of a communication device according to one embodiment of this application. [Figure 12] This is a diagram showing yet another structure of a communication device according to one embodiment of this application. [Figure 13] This is a diagram showing yet another structure of a communication device according to one embodiment of this application. [Figure 14] This is a diagram showing yet another structure of a communication device according to one embodiment of this application. [Figure 15] This is a diagram showing yet another structure of a communication device according to one embodiment of this application. [Modes for carrying out the invention]

[0240] Embodiments of this application provide a communication method and associated apparatus, which, as a result, enable a terminal device to determine whether a random access initiated by the terminal device to a target neighboring cell was successful, based on the feedback status of a serving network device. In this way, the terminal device can determine the access status of a random access while reducing the service interruption time of the terminal device in the serving cell.

[0241] The technical solution of this application will be described below with reference to the attached drawings.

[0242] The technical solutions in this application apply to various communication systems, such as 5G systems and new wireless systems. (N R) System, Long-Term Evolution (L TE) System, LTE frequency division duplexing (F DD) System, LTE Time Division Duplex (T DD) System, Universal Mobile Telecommunications System (U MTS), mobile communication systems after 5G networks (e.g., 6G mobile communication systems), and vehicles versus everything (V 2X) Can be applied to communication systems.

[0243] The communication system to which this application is applicable includes a terminal device, a serving network device, and a candidate network device.

[0244] A terminal device is located in a serving cell. A signal transmitted by a serving network device covers the serving cell of the terminal device, and the serving network device is configured to provide services to the terminal device in the serving cell. A candidate network device is a network device to be handed over, and a signal transmitted by the candidate network device covers the candidate cell, and the candidate network device is configured to provide services to the terminal device in the candidate cell. In this application, the candidate network device is described by using a neighbor cell network device as an example. A signal transmitted by the neighbor cell network device covers the target neighbor cell, which is a neighbor cell of the serving cell of the terminal device. The neighbor cell network device is configured to provide services to the terminal device in the target neighbor cell.

[0245] The terminal device and network device described in this application will be explained below.

[0246] A terminal device may be a wireless terminal device capable of receiving scheduling and indication information from a network device. A terminal device may be a device that provides voice and / or data connectivity to a user, a handheld device with wireless connectivity, or another processing device connected to a wireless modem.

[0247] Terminal devices are user devices. (U E), mobile station (M S), mobile terminal (M T), customer premises equipment (CAlso known as PE (Personal Equipment), a terminal device is a device that includes wireless communication capabilities (to provide voice / data connectivity to the user), such as a handheld device or in-vehicle device with wireless connectivity. Currently, some examples of terminal devices include mobile phones, tablet computers, notebook computers, palmtop computers, and mobile internet devices. (M ID, wearable devices, virtual reality (V R) Devices, Augmented Reality (A R) These include wireless devices, wireless terminals in industrial control, wireless terminals in the Internet of Vehicles, wireless terminals in self-driving, wireless terminals in remote medical surgery, wireless terminals in smart grids, wireless terminals in transportation safety, wireless terminals in smart cities, and wireless terminals in smart homes. For example, a wireless terminal in self-driving could be an unmanned aerial vehicle, helicopter, or airplane. For example, a wireless terminal in the Internet of Vehicles could be an in-vehicle device, vehicle equipment, in-vehicle module, vehicle, or ship; a wireless terminal in industrial control could be a camera, robot, or robotic arm; and a wireless terminal in a smart home could be a television, air conditioner, vacuum cleaner, speaker, or set-top box.

[0248] It should be noted that the terminal device may, alternatively, be a chip, module, or control unit in the possible devices or apparatus described above. This is not particularly limited in this application.

[0249] A network device can be a device in a wireless network. For example, a network device can be a device deployed in a wireless access network and providing a wireless communication function to terminal devices. For example, a network device is a wireless access network that enables a terminal device to access a wireless network (R It can be an AN) node and may also be called an access network device, a RAN entity, an access node, a network node, or a communication device.

[0250] Specifically, a network device can be an access network device in a cellular system related to the Third Generation Partnership Project (3 GPP), such as an access network device in a 4G communication system or a 5G communication system. Alternatively, a network device can be an access network device in an Open Radio Access Network (open RAN, O-RAN, or ORAN), or a Cloud Radio Access Network (C RAN). Alternatively, a network device can be an access network device in a communication system obtained by integrating two or more of the above communication systems.

[0251] A network device includes, but is not limited to, an evolved Node B (e NB), a Radio Network Controller (R NC), a Node B (N B), a Base Station Controller (B SC), a Base Transceiver Station (B TS), a Home Base Station (e.g., a Home evolved NodeB, or a Home NodeB, HNB), a Baseband Unit (B BU), an access point in a Wireless Fidelity (W i-Fi) system (A P), a macro base station, a micro base station, a wireless relay node, a donor node, a radio controller in a CRAN scenario, a wireless backhaul node, a transmission point (TP), transmission and reception points (T This includes RP, etc. Alternatively, network devices include network devices in 5G mobile communication systems, for example, next-generation node B in NR systems. (g This could be a NB), TRP, or TP, or one or a group of antenna panels (including multiple antenna panels) of a base station in a 5G mobile communication system. Alternatively, the network device could be a network node forming a gNB or transmit point, for example, a central unit. (C U), distributed unit (D U), CU-control plane (C P), CU-User Plane (U P) or wireless unit (R U) may be a CU and DU may be located separately or may be included in the same network element, e.g., BBU. RU may be a radio frequency device or radio frequency unit, e.g., a remote radio unit. (R RU), Active Antenna Processing Unit (A AU), or remote wireless head (R It may be included in RH). Alternatively, network devices may be servers, wearable devices, vehicles, in-vehicle devices, etc. For example, in V2X technology, the access network device is a roadside unit. (R It could be SU.

[0252] It should be noted that in different systems, CU (or CU-CP and CU-UP), DU, or RU may have different names, but those skilled in the art will understand the meaning of the names. For example, in an ORAN system, CU may be called O-CU or open CU, DU may be called O-DU, CU-CP may be called O-CU-CP, CU-UP may be called O-CU-UP, and RU may be called O-RU. This is not particularly limited in this application. Any one of CU, CU-CP, CU-UP, DU, and RU in this application may be implemented using a software module, a hardware module, or a combination of a software module and a hardware module.

[0253] Optionally, each network element in the ORAN system may implement the protocol layer functions shown in Table 1.

[0254] [Table 1]

[0255] The architecture of the CU and DU of an access network device is described below. An access network device includes at least one CU and at least one DU. Optionally, the access network device further includes at least one RU.

[0256] In the following, for illustrative purposes, we will use an example in which an access network device includes one CU and one DU. The CU has several core network functions, and the CU may include CU-CP and CU-UP. The CU and DU may be configured based on the protocol layer functions of the wireless network implemented by the CU and DU. For example, the CU may implement the Packet Data Convergence Protocol (PThe DU is configured to implement the functionality of the DCP layer and protocol layers above the PDCP layer (e.g., the RRC layer and / or SDAP layer). The DU implements the functionality of protocol layers below the PDCP layer (e.g., the RLC layer, MAC layer, and / or physical (P In another example, the CU is configured to implement the functionality of protocol layers above the PDCP layer (e.g., the RRC layer and / or SDAP layer), and the DU is configured to implement the functionality of the PDCP layer and protocol layers below the PDCP layer (e.g., the RLC layer, MAC layer, and / or PHY layer).

[0257] When a CU includes a CU-CP and a CU-UP, the CU-CP is configured to implement the control plane functions of the CU, and the CU-UP is configured to implement the user plane functions of the CU. For example, when a CU is configured to implement the functions of the PDCP layer, RRC layer, and SDAP layer, the CU-CP is configured to implement the functions of the RRC layer and the control plane functions of the PDCP layer, and the CU-UP is configured to implement the functions of the SDAP layer and the user plane functions of the PDCP layer.

[0258] CU-CP can interact with network elements configured to implement control plane functions in the core network. Network elements configured to implement control plane functions in the core network include access and mobility function network elements, for example, access and mobility functions in a 5G system. (AIt may be MF). Access and mobility function network elements are configured to handle mobility management in the mobile network, such as updating the location of terminal devices, registering terminal devices with the network, and handing over terminal devices. CU-UP can interact with network elements configured to implement user plane functions in the core network. User plane functions in the core network, for example, user plane functions in a 5G system. (U Network elements configured to implement PF are configured to transfer and receive data on terminal devices.

[0259] The above configurations for CUs and DUs are merely examples. Alternatively, the functionality of CUs and DUs can be configured according to requirements. For example, a CU or DU may be configured to have functionality for more protocol layers, or a CU or DU may be configured to have some processing functionality for a protocol layer. For example, some functionality for the RLC layer and functionality for protocol layers above the RLC layer may be set on the CU, while the remaining functionality for the RLC layer and functionality for protocol layers below the RLC layer may be set on the DU. In another example, the functionality of a CU or DU can be obtained, alternatively, through partitioning based on service type or other system requirements. For example, partitioning may be performed based on latency. In this case, functionality where processing time must meet latency requirements is placed on the DU, and functionality where processing time does not need to meet latency requirements is placed on the CU.

[0260] DUs and RUs can work together to jointly implement the functions of the PHY layer. One DU may be connected to one or more RUs. The functions of DUs and RUs can be configured in multiple ways depending on the design. For example, a DU may be configured to implement baseband functions, and an RU may be configured to implement intermediate radio frequency functions. In another example, a DU may be configured to implement upper-layer functions of the PHY layer, and an RU may be configured to implement lower-layer functions of the PHY layer, or both lower-layer functions and radio frequency functions. Upper-layer functions of the physical layer may include some functions of the physical layer, and these functions are closer to the MAC layer. Lower-layer functions of the physical layer may include other functions of the physical layer, and these functions are closer to the intermediate radio frequency side.

[0261] It should be noted that a network device may be the device or apparatus described above, or a component (e.g., a chip), module, or unit within the device or apparatus described above. This is not particularly limited in this application.

[0262] In this application, the target neighbor cell and the serving cell may be cells on two DUs connected to one CU, or two cells on one DU connected to one CU, or cells on DUs connected to two CUs, respectively. This is not particularly limited in this application.

[0263] If the target neighbor cell and the serving cell are cells on a DU connected to two separate CUs, the CUs communicate with each other via the Xn interface, and the CUs communicate with the DU via the F1-AP interface. If the target neighbor cell and the serving cell are cells on two DUs connected to one CU, the DUs communicate with each other via the F1-AP interface.

[0264] To facilitate an understanding of the technical solutions in the embodiments of the present application, the following shows two possible communication systems to which the methods provided in the embodiments of the present application are applicable, with reference to FIGS. 1 and 2.

[0265] FIG. 1 is a diagram of a communication system according to an embodiment of the present application. As shown in FIG. 1, the communication system includes at least one network device, such as network device 111 shown in FIG. 1. The communication system further includes at least one terminal device, such as terminal devices 121 and 122 shown in FIG. 1. Network device 111 may perform transmissions with terminal devices 121 and 122 by using beams.

[0266] FIG. 2 is another diagram of a communication system according to an embodiment of the present application. As shown in FIG. 2, the communication system may include at least two network devices, such as network devices 211, 212, and 213 shown in FIG. 2. The communication system further includes at least one terminal device, such as terminal device 221 shown in FIG. 2. Terminal device 221 may be provided with communication services by a plurality of network devices. For example, as shown in FIG. 2, network device 211 may perform a transmission with terminal device 221 by using beam 1, network device 212 may perform a transmission with terminal device 221 by using beam 2, and network device 213 may perform a transmission with terminal device 221 by using beam 3. In other words, one terminal device may be provided with communication services simultaneously by a plurality of network devices.

[0267] The following describes possible scenarios to which the present application is applicable. The present application is also applicable to other scenarios, and the scenarios in the following examples do not limit the present application.

[0268] Figure 3 is a diagram illustrating a scenario to which a communication method according to one embodiment of this application may be applied. Please refer to Figure 3. The communication system includes TRP 301, TRP 302, and terminal device 303. Cell 0 is the serving cell of terminal device 303, and cell 1 is a neighboring cell of the serving cell of terminal device 303. TRP 301 provides communication services to terminal device 303. Terminal device 303 may initiate random access to TRP 302 by using the communication method provided in this application. This helps cell 1 calculate the TA of cell 1 and send that TA to cell 0. Cell 0 may add the TA to a handover command and send a handover command to terminal device 303 in order to obtain the TA of cell 1 before terminal device 303 hands over to cell 1, thereby reducing the service interruption time for terminal device 303 in cell 0.

[0269] To facilitate understanding of the technical solutions presented in this application, some technical terms used in this application are explained below.

[0270] 1. Beam: A beam is a communication resource. A beam can be a broad beam, a narrow beam, or another type of beam, and the technique for forming the beam can be beamforming technique or another technical means. Specifically, beamforming techniques can be digital beamforming technique, analog beamforming technique, and hybrid digital / analog beamforming technique. Different beams can be considered different resources.

[0271] In the NR protocol, the beam is filtered by a spatial domain filter, spatial filter, spatial domain parameter, spatial parameter, spatial domain setting, and spatial setting. (QThe beam may be referred to as CL information, QCL assumption, or QCL representation. The beam may be represented by TCI-state parameters or spatial relation parameters. Thus, in this application, the beam may be replaced with spatial domain filter, spatial filter, spatial domain parameter, spatial parameter, spatial domain setting, spatial setting, QCL information, QCL assumption, QCL representation, TCI-state (including uplink TCI-state or downlink TCI-state), spatial relation, etc. The above terms are also equivalent to each other. Alternatively, the beam may be replaced with another term to represent the beam, which is not limited in this application.

[0272] The transmitting end may transmit the same or different information by using different beams. Optionally, multiple beams having the same or similar communication characteristics may be considered as a single beam. One beam may include one or more antenna ports configured to transmit data channels, control channels, sounding signals, etc. The uplink transmit beam may transmit spatial relationships, TCI-states, and sounding reference signals. (S It can be indicated by using one of the following resources (using SRS to indicate the transmit beam). Therefore, the uplink transmit beam can be replaced with an SRS resource as an alternative.

[0273] The beam used to transmit a signal is sometimes called a transmit beam (Tx beam), spatial domain transmission filter, spatial transmission filter, spatial domain transmission parameter, spatial transmission parameter, spatial domain transmission setting, or spatial transmission setting.

[0274] The beam used to receive the signal is the receiving beam. (R It is sometimes called an x-beam, spatial domain reception filter, spatial reception filter, spatial domain reception parameter, spatial reception parameter, spatial domain reception setting, or spatial reception setting.

[0275] For example, the transmit beam may be the signal intensity distribution formed in different directions in space after a signal has been transmitted through an antenna, and the receive beam may be the signal intensity distribution in different directions in space of a radio signal received from an antenna. It can be understood that one or more antenna ports forming a single beam may, alternatively, be considered as a set of antenna ports.

[0276] When low-frequency or intermediate-frequency bands are used, the transmitting end can transmit signals in an omnidirectional manner or wide-angle. When high-frequency bands are used, due to the small carrier wavelength in high-frequency communication systems, antenna arrays containing many antenna elements may be placed at both the transmitting and receiving ends. The transmitting end transmits signals by using specific beamforming weights, resulting in the transmitted signal forming a spatially directional beam, and the receiving end receives the signal by using antenna arrays with specific beamforming weights. This helps increase the received power of the signal at the receiving end and resist path loss.

[0277] 2. Common Beam: Currently, each channel is represented by an independent beam. Each channel has a corresponding beam. In this application, a common beam is defined and used for multiple uplink and / or downlink channels.

[0278] A common beam is the same beam used for multiple channels, multiple types of channels, multiple reference signals, and / or multiple types of reference signals. A channel is, but is not limited to, a physical downlink control channel. (P DCCH, PDSCH, PUCCH, Physical Uplink Shared Channel (P USCH), or physical random access channel (P Includes at least one of the following (RACH). The reference signal is not limited to SSB, CSI-RS, DMRS, or a phase-tracing reference signal. (P TRS), time-frequency tracking reference signal (T It includes at least one of the following: RS, SRS, etc.

[0279] Joint Common Beam: A joint common beam is for transmitting at least one uplink-downlink channel or at least one uplink-downlink reference signal, such as PDCCH, PDSCH, PUCCH, and PUSCH. A joint common beam is sometimes also called an uplink-downlink common beam.

[0280] Uplink Common Beam: The uplink common beam is for transmitting multiple uplink channels and / or multiple types of uplink channels and / or one or more uplink reference signals, such as PUCCH, PUSCH, and SRS.

[0281] Downlink Common Beam: A downlink common beam transmits multiple downlink channels and / or multiple types of downlink channels and / or one or more downlink reference signals, such as PDCCH, PDSCH, and channel state information reference signals. (C This is for transmitting SI-RS signals.

[0282] Common beam format: A common beam may have a newly defined structure (different from existing TCI-states). For example, a common beam may include beam representation-related information, and this beam representation-related information may include, but is not limited to, a common beam identifier. (I D) including one or more of the following: logical cell identifier (cell ID), physical cell identifier, bandwidth sub-identifier, reference signal resource for beam determination, QCL type, uplink power control related parameters (such as path loss measurement reference signal resource, p0, or closed loop index), and path loss reference signal identifier.

[0283] Common beam application scope: A common beam can be cell-specific; that is, one common beam is for the transmission of multiple channels in one cell. The common beam is a bandwidth portion. (BA WP (wavepoint) can be specific and is for transmitting multiple beams in a single BWP. A common beam can also be cross-cell, i.e., for transmitting multiple channels in multiple cells. Multiple cells can be multiple cells in a single band. Alternatively, multiple cells can be multiple interband cells.

[0284] 3. Pseudo-collocation (Q CL): A pseudo-collocation relationship indicates that multiple resources share one or more identical or similar communication characteristics. The same or similar communication configuration may be used for multiple resources with a pseudo-collocation relationship. For example, if two antenna ports have a pseudo-collocation relationship, the large channel characteristics of one port transmitting one symbol can be inferred from the large channel characteristics of the other port transmitting one symbol. Large channel characteristics include delay spread, mean delay, Doppler spread, Doppler frequency shift, mean gain, receive parameters, number of received beams at the terminal device, transmit / receive channel correlation, receive angle of arrival, receiver antenna spatial correlation, and dominant angle of arrival. (A This may include oA, mean angle of arrival, AoA spread, etc. Specifically, the collocation indicator indicates whether at least two groups of antenna ports have a collocation relationship and includes: the collocation indicator indicates whether channel state information reference signals transmitted by at least two groups of antenna ports are from the same transmission point, or the collocation indicator indicates whether channel state information reference signals transmitted by at least two groups of antenna ports are from the same beam group.

[0285] 4. TCI Mode: TCI mode includes joint mode and separate mode. Joint mode means that the same beam is used for both uplink and downlink transmissions between the TRP and the terminal device. Separate mode means that different beams are used for uplink transmissions between the TRP and the terminal device and for downlink transmissions between the TRP and the terminal device.

[0286] 5. TCI: TCI is sometimes called the TCI state (TCI-state). As specified in the communication protocol, the QCL is set by using the TCI state. The parameters of the TCI state are one or two downlink reference signals and the physical downlink shared channel. (P Demodulation reference signal of DSCH (D Used to establish a pseudo-collocation relationship with MRS. Downlink control information (D CI) may include the TCI field, which is a field that is in DCI and indicates pseudo-collocation of PDSCH antenna ports.

[0287] A TCI is set by a network device for a terminal device using an RRC message and is called a TCI state in setting signaling. After the network device has set a TCI state for a terminal device using an RRC message, the network device may send a MAC CE to the terminal device. The MAC is used to activate one or more TCI states in the TCI state set by the network device for the terminal device. Optionally, the network device may further send a DCI to the terminal device. A DCI indicates one of the TCI states activated by the MAC CE.

[0288] A TCI state contains one or two QCL relationships. A QCL relationship represents a specific agreement relationship between the signal / channel to be received now and a previously known reference signal. If a QCL relationship exists, the terminal device can receive or transmit the next signal / channel by inheriting the receive or transmit parameters used to previously receive or transmit the reference signal. Each TCI state corresponds to one beam. The terminal device can perform communication transmissions by using the beam.

[0289] The TCI status type is the Uplink Transmit Setting Indicator. (U L TCI) status, downlink transmit setting indicator (D This includes the L TCI state and the uplink-downlink joint TCI state. The UL TCI state corresponds to the uplink common beam, the DL TCI state corresponds to the downlink common beam, and the uplink-downlink joint TCI state corresponds to the uplink-downlink joint common beam. For more information on the uplink common beam, downlink common beam, and uplink-downlink joint common beam, please refer to the relevant descriptions above.

[0290] The following sections describe TCI status settings, TCI status activation, and TCI status display.

[0291] TCI State Setting: Network devices set multiple TCI states for terminal devices by using RRC signaling. Each of these TCI states contains pseudo-collocation information (QCL-Info) of type D. The type D reference signal is determined by using the type D pseudo-collocation information. For ease of explanation, the type D reference signal will be referred to below as the type D reference signal in the TCI state. Furthermore, a TCI state may further contain another type of pseudo-collocation information, which may be type A, type B, or type C. For example, type A pseudo-collocation information may further contain a reference signal identifier, and the terminal device determines the parameters for receiving another signal or channel based on the Doppler shift, Doppler spread, mean delay, and delay spread of receiving the reference signal. For each reference signal set in the pseudo-collocation information, the network device may further set the serving cell identifier and bandwidth part (BWP) identifier of the reference signal. The TCI state may further include power control parameters and path loss reference signal identifiers used by terminal devices to perform uplink transmission by using the TCI state.

[0292] The TCI state setting is the TCI state setting that a network device indicates to a terminal device in a scenario where the terminal device uses joint mode. When a terminal device uses joint mode, the network device indicates the uplink-downlink joint TCI state to the terminal device.

[0293] When a terminal device uses separate mode, the network device indicates the UL TCI status to the terminal device. Setting the UL TCI status includes setting a reference signal. For example, the reference signal is the SSB, the channel status information reference signal. (CThis is either SSB or CSI-RS. In the following description, the reference signal is referred to as the resource reference signal in the UL TCI state. If the reference signal is SSB or CSI-RS, the terminal device may determine which beam to use for uplink transmission by using the beam to receive the SSB or CSI-RS. The terminal device then performs uplink transmission with the network device by using the beam to use for uplink transmission. If the reference signal is SRS, the terminal device may perform uplink transmission with the network device by using the beam to transmit the SRS. SRS is further associated with the TCI state, which includes setting up a downlink periodic reference signal. The terminal device determines which beam to use to transmit the SRS based on the beam used by the terminal device to receive the downlink periodic reference signal, and then transmits the SRS by using that beam.

[0294] TCI State Activation: After setting multiple TCI states, the network device must further activate eight TCI states within the TCI state by using MAC CE. The eight TCI states have a one-to-one correspondence with the eight values ​​of the TCI field in DCI. In other words, the specific eight TCI states corresponding to the eight values ​​of the TCI field in DCI are determined by using MAC CE.

[0295] TCI Status Indication: Network devices indicate specific TCI states via the TCI field in the DCI. For example, if the value of the TCI field in the DCI sent by a network device to a terminal device is 000, this indicates that the TCI state corresponding to 000 is used for the data transmission beam. Pseudo-collocation information where type is typeD in the TCI state. (Q The reference signal included in CL-Info is the channel state information reference signal with index #1. (CThis is SI-RS, which indicates that the beam used for data transmission is the same as the receiving beam corresponding to the CSI-RS with index #1. The receiving beam corresponding to the CSI-RS with index #1 can be determined through a beam measurement procedure and is known to the terminal device. Thus, the terminal device can transmit or receive data by determining the beam corresponding to the data transmission beam based on a specific value in the TCI field and using the corresponding receiving beam.

[0296] Please note that the two descriptions in this specification, namely TCI-state and TCI-state, are interchangeable.

[0297] 6. Random Access Resources: Random access resources are used by terminal devices to initiate random access to network devices. Random access resources provide several random access opportunities. (R It is formed by O). When initiating random access, the terminal device first detects the SSB with the highest received signal strength. The terminal device determines a random access opportunity based on the number of SSBs sent out by the network device (the terminal device knows the number of SSBs by using system messages broadcast by the network device) and the SSB association settings in the random access resource configuration. The terminal device then initiates random access to the network device by using the random access opportunity. Hereafter, an SSB will be briefly referred to as an SSB associated with a random access resource. The resource for sending out SSBs is called an SSB resource, and an SSB resource may be briefly referred to as an SSB resource associated with a random access resource.

[0298] 7. Serving Cell: A serving cell is a cell to which terminal devices camp on. Terminal devices can communicate and transmit data to the serving cell.

[0299] 8. Target neighboring cell: The target neighboring cell is its physical cell identifier. (P The CI (Continuous Intermediate) is a different cell from the PCI (Continuing Intermediate) of the serving cell of the terminal device. For example, the target neighbor cell is a cell adjacent to the serving cell, or the target neighbor cell and the serving cell are two cells covered by the same site.

[0300] 9. Target Neighbor Cell TA: The Target Neighbor Cell TA is the timing advance used by terminal devices to send uplink signals to target neighbor cells.

[0301] 10. Control Resource Set: The control resource set represents a frequency domain resource set for physical downlink control channel transmission, is a parameter setting unit for physical downlink control channel transmission, and includes the relevant setting parameters for the physical downlink control channel.

[0302] 11. Search Space: The search space represents a time-domain location set for physical downlink control channel transmissions and time-frequency locations corresponding to multiple physical downlink control channel resources in the search space. For example, the search space defines physical downlink control channel transmission periodicity, i.e., the periodicity of physical downlink control channel opportunities in the search space. A physical downlink control channel can actually be understood as a detection point or detection time period of a physical downlink control channel in the time domain. For example, a time unit is a slot, and one physical downlink control channel transmission periodicity contains P slots. Furthermore, the search space represents the offset value of the starting slot of the physical downlink control channel transmission periodicity, e.g., S. In this case, one physical downlink control channel transmission periodicity corresponds to one time window, where the starting slot number is S + P * n and the ending slot number is S + P * (n + 1) - 1, where n is a positive integer and P is a positive integer. Furthermore, the search space represents consecutive slots in which physical downlink control channel opportunities reside and during physical downlink control channel transmission periodics, and symbols on which physical downlink control channel opportunities lie and within these slots.

[0303] Random access is a necessary process for establishing a wireless link between a terminal device and a network device. Communication transmission can only be successfully performed between the terminal device and the network device after random access has been successful. The terminal device may implement uplink synchronization with the network device during the random access procedure. That is, the terminal device may obtain a TA (Terminal Adapter) of the cell it requests to access and use that TA to perform uplink transmission with the cell. Furthermore, during the random access procedure, the network device may assign a unique identifier, such as C-RNTI, to the terminal device.

[0304] Currently, types of random access procedures include contention-based random access procedures and contention-free random access procedures.

[0305] The following describes a contention-based random access procedure with reference to Figure 4. Figure 4 is a diagram of a contention-based random access procedure according to one embodiment of this application. Please refer to Figure 4. This method includes the following steps.

[0306] 401: Terminal device sends message 1 to network device (M Send SG1). Message 1 contains a random access request.

[0307] Specifically, a random access request involves the preamble and the random access of the terminal device. wireless Network Temporary Identifier (R The preamble, which includes A-RNTI, is used by the terminal device to request access to the target neighboring cell. The terminal device's RA-RNTI is generated by the terminal device according to a predefined expression or rule in the communication protocol.

[0308] 402: The network device sends message 2 to the terminal device. Message 2 is a random access response. (R It is sometimes called AR.

[0309] After sending message 1, the terminal device monitors the PDCCH during the RAR time window to receive the corresponding RA-RNTI RAR. If the network device does not receive a response RAR using it during the RAR time window, the current random access is considered to have failed.

[0310] After a terminal device has successfully received a RAR (decrypted it using its RA-RNTI), if the index of the preamble in the RAR is the same as the index of the preamble sent by the terminal device in the random access request, the terminal device is considered to have successfully received the RAR. In this case, the terminal device may stop monitoring the RAR.

[0311] 403: The terminal device sends message 3 to the network device.

[0312] Message 3 contains a unique identifier for the terminal device. This unique identifier is used for conflict resolution in step 404.

[0313] In the case of a terminal device in RRC connection mode, the unique identifier for the terminal device is C-RNTI.

[0314] For terminal devices in RRC non-connected mode, the unique identifier of the terminal device is an identifier that uniquely identifies the terminal device from the core network, for example, System Architecture Evolution Temporary Mobile Subscriber Identifier. (S -TMSI), or a random number. In this case, the network device must first communicate with the core network, and as a result, the network device can respond to message 3 sent by the terminal device in step 404.

[0315] 404: The network device sends message 4 to the terminal device.

[0316] Message 4 carries the terminal device's unique identifier, indicating that the terminal device won the conflict resolution process, i.e., that the terminal device successfully performed random access.

[0317] Specifically, in a contention-based random access procedure, multiple terminal devices may send random access requests on the same resource. Therefore, these random access requests will conflict. When a network device decides to respond to one of the terminal devices, it indicates that a conflict resolution occurs for that terminal device.

[0318] Note that if message 4 carries a unique identifier for another terminal device, it indicates that random access for that terminal device has failed, and the terminal device needs to restart random access.

[0319] In a handover scenario, network devices may configure separate random access resources for terminal devices. For terminal devices, contention resolution is not required. The type of random access procedure is contention-free random access. (C It is sometimes called the FRA procedure.

[0320] The following describes a contention-free random access procedure with reference to Figure 5. Figure 5 is a diagram of a contention-free random access procedure according to one embodiment of this application. Please refer to Figure 5. This method includes the following steps.

[0321] 501: The network device allocates the preamble and individual random access resources to the terminal device.

[0322] Network devices pre-allocate preambles and individual random access resources to terminal devices, so that terminal devices can later understand which terminal device will send a random access request.

[0323] 502: The terminal device sends message 1 to the network device.

[0324] Message 1 includes a random access request. Specifically, the random access request includes a preamble allocated to the terminal device by the network device in step 501. The terminal device may send Message 1 to itself by using the individual random access resources allocated to it by the network device in step 501.

[0325] 503: The network device sends message 2 to the terminal device.

[0326] Specifically, the network device may calculate the TA of the cell that the terminal device requests access to, based on the preamble in message 1 in step 502. The network device then adds the TA to message 2 and sends message 2 to the terminal device.

[0327] Optionally, the network device allocates uplink resources to the terminal device to perform uplink transmission between the terminal device and the network device.

[0328] Optionally, Message 2 includes information about uplink resources.

[0329] As illustrated in the embodiment shown in Figure 5, random access by a terminal device is completed by using a two-step random access procedure. In the embodiment shown in Figure 5, the terminal device performs random access by using a preamble and individual random access resources allocated by the network device. This can be understood as a contention-free random access procedure. In practical application, step 501 may be replaced by the terminal device selecting a preamble and random access resources. In this case, the embodiment shown in Figure 5 is a contention-based random access procedure. (C This can be understood as a BRA procedure.

[0330] When a terminal device performs a cell handover, it cannot receive data or information from the serving cell. As a result, the terminal device's service in the serving cell is interrupted. To reduce the service interruption time for the terminal device in the serving cell, the standard agrees that, before performing a cell handover, the terminal device should obtain the terminal device's Terminal Address (TA) in the cell to which it will hand over. Specifically, the terminal device is located in the serving cell and may initiate random access to the cell to which it will hand over. The specific random access procedure includes the following: The terminal device sends a preamble to the cell to which it will hand over. The terminal device then waits to receive a response message from the cell to which it will hand over regarding the preamble, and the response message includes the terminal device's TA in the cell to which it will hand over.

[0331] However, in random access procedures, terminal devices cannot continue communication with the serving cell. Therefore, the service of the serving cell is interrupted. To further reduce the service interruption time for terminal devices in the serving cell, the following solution is proposed: After sending the preamble, the terminal device does not need to wait to receive a response message from the cell to which the terminal device will hand over. The serving cell can obtain the terminal device's TA in the cell from the cell to which the terminal device will hand over, and send the TA to the terminal device by using a handover command.

[0332] However, if a terminal device does not wait for a response message regarding the preamble from the cell to which it will hand over, it cannot determine whether its random access was successful. In this way, the terminal device can determine the access status of its random access while reducing the service interruption time for the terminal device in the serving cell.

[0333] Furthermore, even if the serving cell detects a random access from the terminal device, the serving cell will re-trigger the terminal device to initiate a random access. The terminal device is unaware that the random access request will be retransmitted. Therefore, the terminal device will not increase the power to send the random access request. As a result, the random access from the terminal device fails because it does not have sufficient transmit power to send the random access request.

[0334] This application provides a corresponding technical solution, which allows a terminal device to determine whether a random access initiated by the terminal device to a target neighboring cell was successful, based on the feedback status of the serving network device. In this way, the terminal device can determine the access status of a random access while reducing the service interruption time for the terminal device in the serving cell.

[0335] The technical solution of this application is described below with reference to specific embodiments.

[0336] Figure 6 is a diagram illustrating an embodiment of the communication method according to the present invention. Please refer to Figure 6. This method includes the following steps.

[0337] 601: A terminal device sends a random access request to a neighboring cell network device.

[0338] Random access requests are used by terminal devices to request access to a target neighboring cell. The target neighboring cell is a neighboring cell of the terminal device's serving cell. Neighboring cell network devices correspond to the target neighboring cell, signals transmitted by neighboring cell network devices cover the target neighboring cell, and neighboring cell network devices provide services to terminal devices within the target neighboring cell.

[0339] For example, as shown in Figure 3, terminal device 303 is located within a serving cell (cell 0). The target neighboring cell is cell 1, and the neighboring cell network device is TRP 302. Signals transmitted by TRP 302 cover cell 1 and provide services to cell 1.

[0340] The following describes the technical solution of this application, referring to the reception status upon receiving a random access request by a neighboring cell network device.

[0341] In particular, the cases in which a neighboring cell network device receives a random access request include Case 1 and Case 2. In Case 1, the neighboring cell network device does not receive a random access request from the terminal device. In Case 2, the neighboring cell network device receives a random access request from the terminal device.

[0342] In the following section, Case 1 will be explained by referring to steps 602 through 604.

[0343] 602: If a neighboring cell network device does not receive a random access request from a terminal device, the neighboring cell network device either sends a third feedback message to the serving network device, or the neighboring cell network device does not send a feedback message to the serving network device.

[0344] The third feedback message indicates that the neighboring cell network device did not receive a random access request from the terminal device. Alternatively, the third feedback message indicates that the random access to the target neighboring cell initiated by the terminal device failed.

[0345] Optionally, a neighboring cell network device not receiving random access requests from a terminal device includes one of the following:

[0346] Neighboring cell network devices do not receive random access requests from terminal devices within a first time window specified by the protocol, or within a preset first time window.

[0347] Alternatively, neighboring cell network devices will not receive random access requests from terminal devices before a preset first timer expires.

[0348] Optionally, the length of the first time window specified in the protocol, or a preset length of the first time window, may be one or more random access channel resource periods.

[0349] 603: If a serving network device does not receive a feedback message from a neighboring cell network device regarding a random access request from a terminal device, or if the serving network device receives a third feedback message from a neighboring cell network device, the serving network device sends at least one of the first feedback message or the first scheduling signaling to the terminal device, or the serving network device does not send a feedback message to the terminal device.

[0350] The first feedback message indicates that the random access attempt by the terminal device failed. The first scheduling signaling is used to schedule the terminal device to resend the random access request.

[0351] Optionally, a serving network device not receiving feedback messages from neighboring cell network devices regarding random access requests from terminal devices includes one of the following:

[0352] A serving network device does not receive feedback messages from neighboring cell network devices regarding random access requests within a second time window specified by the protocol, or within a preset second time window.

[0353] Alternatively, neighboring cell network devices will not receive feedback messages from other neighboring cell network devices regarding random access requests before a preset second timer expires.

[0354] If a serving network device does not receive a feedback message from a neighboring cell network device regarding a random access request from a terminal device, or if the serving network device receives a third feedback message from a neighboring cell network device, the serving network device implements one of the following:

[0355] Implementation 1: The serving network device sends a first feedback message to the terminal device. That is, the serving network device provides feedback to the terminal device that the terminal device's random access failed.

[0356] Optionally, the first feedback message includes power ramping parameters. For example, the power ramping parameters include a power ramping value or power ramping stages. If a terminal device retransmits a random access request multiple times, the terminal device must accumulate power ramping stages each time. That is, the transmit power for each random access request is increased by power ramping stages compared to the transmit power for the last random access request.

[0357] Implementation 2: The serving network device sends a first scheduling signaling to the terminal device.

[0358] Optionally, the first scheduling signaling includes second indication information, which indicates that the terminal device should retransmit the random access request. Thus, the terminal device can use the second indication information to distinguish whether the random access request is being retransmitted or sent initially.

[0359] Optionally, the first scheduling signaling further includes at least one of the third indication information or power ramping parameters.

[0360] The third indication information shows whether the terminal device should increase power to send random access requests.

[0361] For example, power ramping parameters include power ramping values ​​or power ramping stages.

[0362] In a possible implementation, if third indication information indicates that the terminal device should increase the power to send a random access request, the terminal device may increase the power to send the random access request according to a preset rule. Alternatively, the third indication information may further include power ramping parameters. The terminal device retransmits the random access request based on the power ramping parameters.

[0363] In this implementation, a serving network device can indirectly indicate to a terminal device that it should retransmit random access requests by using power ramping parameters.

[0364] Optionally, the first scheduling signaling includes first resource configuration information, which is used by the terminal device to retransmit random access requests. For example, the first resource configuration information includes random access channels of target neighboring cells used by the terminal device to retransmit random access requests. (R Includes ACH resources.

[0365] Implementation 3: The serving network device does not send feedback messages to the terminal device.

[0366] In this implementation, a terminal device may monitor feedback messages from a serving network device. If no feedback messages are detected from the serving network device within a certain time, the terminal device may determine that its random access has failed.

[0367] Terminal devices do not need to wait for responses from neighboring cell network devices for random access requests; instead, they wait for feedback messages from the serving network device for random access requests, which helps reduce service interruption time for terminal devices within the serving cell. In particular, terminal devices do not need to monitor responses from neighboring cell network devices for random access requests within a corresponding time window by using pre-configured resources.

[0368] 604: If the terminal device does not receive a feedback message from the serving network device regarding the random access request, or if the terminal device receives at least one of the first feedback message or the first scheduling signaling from the serving network device, the terminal device retransmits the random access request.

[0369] Optionally, a terminal device failing to receive feedback messages from a serving network device regarding a random access request includes the following: The terminal device fails to receive feedback messages from a serving network device regarding a random access request within a preset time.

[0370] In possible implementations, terminal devices retransmit random access requests to neighboring cell network devices based on a pre-configured number of retransmissions and / or pre-configured power ramping parameters.

[0371] In this implementation, the serving network device may pre-configure the number of retransmissions and / or power ramping parameters for the terminal device. For example, the terminal device may increase its transmit power based on the power ramping parameters and retransmit random access requests by using that transmit power.

[0372] In another possible implementation, the first feedback message or first scheduling signaling further includes power ramping parameters. The terminal device retransmits random access requests to neighboring cell network devices based on the power ramping parameters.

[0373] After step 604, the serving network device may retry receiving feedback messages from neighboring cell network devices about random access requests retransmitted by terminal devices. The serving network device may then send corresponding feedback to terminal devices based on the feedback status of neighboring cell network devices.

[0374] Case Study 2 will be explained below, referring to steps 605 through 607.

[0375] 605: When a neighboring cell network device receives a random access request from a terminal device, the neighboring cell network device sends a fourth feedback message to the serving network device.

[0376] The fourth feedback message indicates that a neighboring cell network device has successfully received the random access request.

[0377] Optionally, the fourth feedback message includes at least one of the following: the Target Audience (TA) of the target neighboring cell, the identifier assigned to the terminal device by the target neighboring cell, or the uplink resource assigned to the terminal device by the target neighboring cell.

[0378] After a neighboring cell network device receives a random access request from a terminal device, the neighboring cell network device may calculate the Target Address (TA) of the target neighboring cell based on the preamble carried in the random access request. The neighboring cell network device may further allocate the C-RNTI and uplink resources to the terminal device. The C-RNTI is the identifier of the terminal device within the target neighboring cell. The uplink resources are used by the neighboring cell network device to perform uplink transmissions with the terminal device.

[0379] 606: If a serving network device receives a fourth feedback message from a neighboring cell network device, the serving network device sends at least one of the second feedback message or the first indication information to the terminal device, or the serving network device does not send a feedback message to the terminal device.

[0380] The second feedback message indicates that the random access by the terminal device was successful. The first indication information indicates that the terminal device will not retransmit the random access request to neighboring cell network devices.

[0381] In this implementation, the serving network device sends a first indication to the terminal device to indirectly indicate that the terminal device's random access was successful.

[0382] 607: The terminal device determines, based on the second feedback message, that the random access of the terminal device was successful.

[0383] According to the technical solution of this application, it can be understood that a terminal device can determine the access status of random access of the terminal device based on the feedback status of the serving network device.

[0384] It should be noted that in this embodiment, the random access procedure used between the terminal device and the neighboring cell network device may be the random access procedure shown in Figure 5, i.e., a contention-free random access procedure.

[0385] Optionally, the embodiment shown in Figure 6 further includes step 601a. ​​Step 601a may be performed before step 601.

[0386] 601a: The serving network device sends a third scheduling signaling to the terminal device. Correspondingly, the terminal device receives the third scheduling signaling from the serving network device.

[0387] The third scheduling signaling method is used to schedule terminal devices to initiate random access to target neighboring cells.

[0388] Optionally, a third scheduling signaling includes the second resource configuration information. This second resource configuration information is used by the terminal device to initially send random access requests.

[0389] For example, the second resource configuration information includes the RACH resource of the target neighboring cell used by the terminal device to initially send a random access request. Correspondingly, step 601 specifically includes the following: The terminal device sends a random access request to the neighboring cell network device by using the RACH resource.

[0390] Optionally, the first resource configuration information and the second resource configuration information in the first scheduling signaling may be the same, and the network device may indirectly indicate that it is scheduling the terminal device to retransmit random access requests by using the first scheduling signaling.

[0391] Optionally, a third scheduling signaling is carried in the DCI. The DCI further indicates whether a feedback message exists for the terminal device's random access request. For example, the DCI includes a first field, and when the value of the first field is 1, it indicates that a feedback message exists for the terminal device's random access request and the terminal device should wait for that feedback message. When the value of the first field is 0, it indicates that there is no feedback message for the terminal device's random access request and the terminal device does not need to wait for that feedback message. Thus, the terminal device can continue to communicate with the serving network device. In this embodiment, we mainly describe a solution in which the first field indicates that there is no feedback message for the terminal device's random access request.

[0392] When the DCI further indicates that a feedback message exists regarding the random access request of the terminal device, the DCI further indicates to the terminal device to wait for the feedback message regarding the random access request to be received from a neighboring cell network device or a serving network device. For example, the DCI includes a second field, and when the value of the second field is 1, the terminal device is indicated to wait for the feedback message regarding the random access request to be received from a neighboring cell network device. When the value of the second field is 0, the terminal device is indicated to wait for the feedback message regarding the random access request to be received from a serving network device. In this embodiment, the solution mainly describes waiting for the terminal device to receive a feedback message regarding the random access request from a serving network device.

[0393] Optionally, the embodiment shown in Figure 6 further includes step 601b. Step 601b may be performed before step 601.

[0394] 601b: The serving network device sends a fourth indication to the terminal device. Correspondingly, the terminal device receives the fourth indication from the serving network device.

[0395] The fourth indication indicates that the terminal device should not wait for feedback messages from neighboring cell network devices regarding random access requests.

[0396] In this implementation, the terminal device performs random access. request Whether to wait for feedback messages from neighboring cell network devices can be configured by the serving network device. Thus, whether a terminal device waits for feedback messages from neighboring cell network devices regarding random access requests is flexibly configured. If the serving network device configures the terminal device to wait for feedback from neighboring cell network devices, the solution described in the background technology is implemented.

[0397] Optionally, the embodiment shown in Figure 6 further includes steps 608 and 609. Steps 608 and 609 may be performed after step 604 or step 607.

[0398] 608: The serving network device sends a handover command to the terminal device. In response, the terminal device receives a handover command from the serving network device.

[0399] The handover command indicates that the terminal device should hand over to a target neighboring cell.

[0400] 609: The terminal device determines at least one of the following: uplink resources, uplink transmit beam, uplink transmit power, or TA of the target neighboring cell.

[0401] Uplink resources are used by terminal devices to perform uplink transmissions with target neighboring cells. Uplink resources include PUSCH resources and / or PUCCH resources. The uplink transmit beam is the beam used by terminal devices to perform uplink transmissions using target neighboring cells. The uplink transmit power is the power used by terminal devices to perform uplink transmissions using target neighboring cells. The TA of the target neighboring cell is the TA used by terminal devices to send uplink signals to the target neighboring cell.

[0402] The following describes several possible implementations in which the terminal device determines the uplink resource.

[0403] Implementation 1: The terminal device uses a pre-configured individual PUCCH resource or a pre-configured CG-PUSCH resource as an uplink resource.

[0404] Implementation 2: The terminal device determines the uplink resource by using a handover command, and the handover command includes the uplink resource.

[0405] Implementation 3: The terminal device monitors a second scheduling signaling sent by a neighboring cell network device for a pre-configured time-frequency resource, and this second scheduling signaling indicates an uplink resource.

[0406] In implementation 3, when no uplink resources are pre-configured for a terminal device, the terminal device monitors a second scheduling signal sent by a neighboring cell network device using pre-configured time-frequency resources.

[0407] Optionally, a pre-configured time-frequency resource is determined by the terminal device based on a specific search space and a specific set of control resources. Optionally, the specific search space and the specific set of control resources may be configured by the serving network device for the terminal device during cell handover, or may be all search spaces and control resource sets configured by the serving network device for the terminal device. This is not particularly limited in this application.

[0408] Optionally, the terminal device sends at least one of the following to a neighboring cell network device using an uplink resource: indication information 1, measurement result 1, measurement result 2, or the beam index of a target neighboring cell tracked or activated by the terminal device.

[0409] Indication information 1 indicates that the terminal device has handed over to a neighboring cell network device. Measurement result 1 includes measurement results obtained by the terminal device by measuring a reference signal sent by the serving cell. For example, measurement result 1 includes the identifier of the reference signal sent by the serving cell and the signal strength of the reference signal. Measurement result 2 includes measurement results obtained by the terminal device by measuring a reference signal sent by the target neighboring cell. For example, measurement result 2 includes the identifier of the reference signal sent by the target neighboring cell and the signal strength of the reference signal.

[0410] Optionally, the terminal device may determine the uplink transmit power, which includes steps a through c.

[0411] Step a: The terminal device determines the first path loss reference signal.

[0412] The following describes several possible implementations of step a.

[0413] Implementation 1: If the handover command further includes the activated TCI state of the target neighboring cell, the first path loss reference signal is the path loss reference signal associated with the activated TCI state.

[0414] It can be understood from the above explanation that a TCI state may include a path loss reference signal identifier, that is, a TCI state may include an associated path loss reference signal. The first path loss reference signal may be a path loss reference signal associated with an activated TCI state.

[0415] Optionally, a QCL relationship exists between the reference signal resource for type D of an activated TCI state and the random access resource used by the terminal device to send random access requests. Alternatively, the path loss reference signal associated with an activated TCI state is the SSB associated with the random access resource used by the terminal device to send random access requests. Alternatively, a QCL relationship exists between the resource used to send the path loss reference signal associated with an activated TCI state and the SSB resource associated with the random access resource.

[0416] For example, as shown in Figure 7, the receiving beam used by a terminal device to receive SSB associated with a random access resource from a neighboring cell network device is beam 1 shown in Figure 7. Beam 1 is a broad beam. The beam corresponding to the activated TCI state is beam 2, which is a narrow beam and belongs to beam 1.

[0417] Implementation 2: If the handover command further includes a deactivation TCI state for the target neighboring cell, the first path loss reference signal is an SSB associated with a random access resource used by the terminal device to send a random access request.

[0418] Implementation 3: If the handover command further includes a reference signal for the target neighbor cell, the first path loss reference signal is the reference signal for the target neighbor cell.

[0419] Step b: The terminal device determines the path loss between the neighboring cell network device and the terminal device based on the first path loss reference signal.

[0420] Specifically, the terminal device measures the first path loss reference signal and obtains the received power for the terminal device to receive the first path loss reference signal. The neighboring cell network device can notify the terminal device in advance of the transmit power for the neighboring cell network device to send out the first path loss reference signal. The terminal device and Serving The path loss between network devices is determined using transmit power and receive power. That is, the path loss between a neighboring cell network device and a terminal device is equal to the transmit power minus the receive power.

[0421] Step c: The terminal device determines the uplink transmit power based on the path loss reference signal.

[0422] Optionally, the handover command further includes power control parameters associated with an activated TCI state or a deactivated TCI state. Step c specifically includes the terminal device determining uplink transmit power based on path loss and power control parameters.

[0423] Optionally, a terminal device performs uplink transmission to a neighboring cell network device based on path loss. In particular, after the terminal device determines the path loss between the terminal device and the neighboring cell network device based on a first path loss reference signal, the terminal device compensates for the uplink signal based on the path loss (i.e., increases the transmission power of the uplink signal by referencing the path loss) and sends the uplink signal to the neighboring cell network device. In this way, power is secured on the neighboring cell network device side for receiving the uplink signal, so the neighboring cell network device parses the uplink signal, thereby improving communication performance.

[0424] The following describes several possible implementations in which the terminal device determines the uplink transmit beam.

[0425] Implementation 1: If the handover command includes a TCI state indicated by a neighboring cell network device for the terminal device, the terminal device determines the uplink transmit beam based on the TCI state indicated in the handover command.

[0426] Optionally, a QCL relationship exists between a reference signal resource of type D TCI state indicated in a handover command and an SSB resource associated with a random access resource used by a terminal device to send a random access request.

[0427] Implementation 2: If the TCI state indicated in the handover command is a downlink TCI state, the terminal device determines the uplink transmit beam based on the SSB receive beam associated with the random access resource used to send the random access request.

[0428] Specifically, the terminal device uses spatial filter parameters for receiving SSB by the terminal device as spatial filter parameters used to transmit the uplink signal.

[0429] The following describes several possible implementations in which a terminal device determines the target neighboring cell (TA).

[0430] Implementation 1: If the handover command includes a Target Audience (TA) of a target neighboring cell, the terminal device uses the TA of the handover command as the TA of the target neighboring cell.

[0431] Implementation 2: If the handover command does not include the target neighboring cell's TA, the terminal device defaults to assuming the target neighboring cell's TA is equal to 0.

[0432] Implementation 3: If the handover command does not include the TA of the target neighboring cell, the terminal device uses the TA carried in the second feedback message as the TA of the target neighboring cell.

[0433] Optionally, if the first condition is met, the terminal device uses the TA carried in the second feedback message as the TA of the target neighboring cell. The first condition includes any one of the following:

[0434] A QCL relationship exists between the reference signal resource of type D in the TCI state indicated in the handover command and the SSB resource associated with the random access resource used by the terminal device to send random access requests.

[0435] Alternatively, the path loss reference signal associated with the TCI state indicated in the handover command is the SSB associated with the random access resource used by the terminal device to send random access requests.

[0436] Alternatively, there is a QCL relationship between the resource used to send the path loss reference signal associated with the TCI state indicated in the handover command and the SSB associated with the random access resource used by the terminal device to send random access requests.

[0437] Implementation 4: If the handover command includes an uplink timing advance indication, and this uplink timing advance indication indicates that the terminal device should determine the target neighbor cell's TA, the terminal device uses the target neighbor cell's TA determined by the terminal device as the target neighbor cell's TA.

[0438] Implementation 5: If the handover command includes a TAG ID, the terminal device uses the TA associated with the TAG ID as the TA of the target neighboring cell.

[0439] Optionally, the TAG ID is associated with at least one serving cell before the terminal device handovers over, and therefore the TA associated with the TAG ID is the TA of at least one serving cell. The TA of at least one serving cell is used as a timing advance by the terminal device to send uplink signals to at least one serving cell.

[0440] Optionally, the TAG ID is associated with one TRP to which the terminal device was connected before the handover; therefore, the TA associated with the TAG ID is the TA associated with the TRP. In other words, the terminal device sends an uplink signal to the TRP by using the TA associated with the TRP.

[0441] Optionally, the TAG ID is associated with at least one reference signal that is set up in the serving cell and measured by the terminal device before the terminal device handover. This reference signal may be SSB, CSI-RS, or a path loss reference signal. (P It could be L-RS.

[0442] Implementation 6: If the handover command does not include the TA of the target neighbor cell, and the target neighbor cell is the terminal device's current serving cell, the terminal device remembers the TA of the target neighbor cell. The terminal device may determine the TA of the target neighbor cell.

[0443] Implementation 6 mainly involves carrier aggregation. (C A) Applies to the scenario. The serving cell of the terminal device is a multiple component carrier. (C C) may be included, and this CC may in particular be a primary CC and a secondary CC. The target neighbor cell may be one of the serving cells, i.e., the terminal device switches the secondary CC to the primary CC.

[0444] From the aforementioned technical solution, it can be understood that the terminal device does not need to wait for a response from a neighboring cell network device for a random access request, but rather waits for a feedback message from the serving network device for the random access request, thereby helping to reduce service interruption time for terminal devices in the serving cell. Furthermore, if the terminal device does not receive a feedback message from the serving network device for the random access request, or if the terminal device receives at least one of the first feedback message or the first scheduling signaling from the serving network device, the terminal device may retransmit the random access request to the neighboring cell network device. In this way, the terminal device can determine whether the random access of the terminal device was successful based on the feedback status of the serving network device. Thus, in the technical solution of this application, the terminal device can determine the access status of a random access while reducing service interruption time for terminal devices in the serving cell.

[0445] Figure 8 illustrates another embodiment of the communication method according to the embodiments of this application. Please refer to Figure 8. This method includes the following steps.

[0446] 801: A terminal device sends message A to a neighboring cell network device. Message A includes a preamble and uplink information.

[0447] The preamble is used by the terminal device to initiate random access to target neighboring cells.

[0448] A target neighboring cell is a neighboring cell of the serving cell of a terminal device, and neighboring cell network devices correspond to the target neighboring cell. Signals transmitted by neighboring cell network devices are used to cover and serve the target neighboring cell.

[0449] Optionally, uplink information is transmitted via PUSCH.

[0450] Optionally, uplink information may include an identifier for the terminal device, such as the C-RNTI used by terminal devices within the serving cell.

[0451] Furthermore, optionally, the uplink information may include the identifier of a reference signal with the best or best signal quality of the target neighboring cell, which is acquired by the terminal device through measurement, or the uplink information may include the beam index of the target neighboring cell tracked or activated by the terminal device.

[0452] Optionally, the embodiment shown in Figure 8 further includes step 801a. Step 801a may be performed before step 801.

[0453] 801a: The terminal device sends a second scheduling signaling to a neighboring cell network device.

[0454] The second scheduling signaling indicates that the terminal device should initiate random access to target neighboring cells.

[0455] In possible implementations, the second scheduling signaling further includes the first indication information. The first indication information tells the terminal device to initiate random access to a target neighboring cell using a first random access scheme. The first random access scheme involves the terminal device sending message A to the target neighboring cell, which includes a preamble and uplink information. That is, the terminal device further sends uplink information when it processes the random access request.

[0456] In another possible implementation, the terminal device pre-configures a random access resource used to send the preamble and a resource used to send uplink information. Thus, after the terminal device receives the second scheduling signaling, it defaults to initiating random access to target neighboring cells using the first random access method.

[0457] The following describes the technical solution of this application, referring to the reception status upon receiving message A by a neighboring cell network device.

[0458] Case 1: A neighboring cell network device successfully receives message A sent by a terminal device. Case 2: A neighboring cell network device successfully receives only the preamble in message A from the terminal device. In other words, the neighboring cell network device fails to receive the uplink information.

[0459] Case 1 will be explained below with reference to steps 802 and 803.

[0460] 802: If a neighboring cell network device successfully receives message A, it sends a successful Random Access Response (RAR) message to the serving network device.

[0461] In this implementation, neighboring cell network devices successfully receive the preamble and uplink information in message A.

[0462] Optionally, a successful random access response message may include an identifier for a PUCCH resource configured by a neighboring cell network device for the terminal device. The PUCCH resource is used by the terminal device to send a reference signal to the target neighboring cell after the terminal device has handed over to the target neighboring cell.

[0463] Optionally, a successful random access response message may further include the target neighbor cell's TA. In particular, after a neighbor cell network device receives message A, the neighbor cell network device may calculate the target neighbor cell's TA based on the preamble in message A and feed that TA back to the serving network device using the successful random access response message.

[0464] 803: The serving network device sends a first feedback message to the terminal device. The first feedback message indicates that the random access to the target neighbor cell initiated by the terminal device was successful, and further indicates the PUCCH resources used by the terminal device to perform uplink transmissions with the target neighbor cell.

[0465] The PUCCH resource is used by the terminal device to send a reference signal to the target neighboring cell after the terminal device has handed over to the target neighboring cell.

[0466] Optionally, the first feedback message may further include the Target Aspect (TA) of the target neighboring cell.

[0467] Case 2 will be explained below with reference to steps 804 and 805.

[0468] 804: If a neighboring cell network device successfully receives only the preamble in message A, the neighboring cell network device sends a fallback random access response (fallback RAR) message to the serving network device.

[0469] In this implementation, neighboring cell network devices successfully receive only the preamble in message A, but fail to receive the uplink information.

[0470] 805: The serving network device sends a second feedback message to the terminal device. The second feedback message either indicates that the random access to the target neighbor cell initiated by the terminal device was successful, or that the terminal device successfully fed back the preamble to the target neighbor cell.

[0471] Optionally, the second feedback message further includes the first scheduling signaling, which indicates that the terminal device should retransmit the uplink information in message A, or indicates that the terminal device should retransmit message A.

[0472] In this implementation, if a neighboring cell network device fails to receive the preamble in message A, the serving network device may trigger the terminal device to retransmit message A or the uplink information within message A.

[0473] Optionally, the second feedback message further includes at least one of the identifiers of a PUCCH resource set up for the terminal device by a neighboring cell network device, or the TA of the target neighboring cell.

[0474] Optionally, the embodiment shown in Figure 8 further includes steps 806 and 807. Steps 806 and 807 may be performed after step 803 or step 805.

[0475] 806: The serving network device sends a handover command to the terminal device.

[0476] 807: The terminal device determines at least one of the following: uplink resources, uplink transmit beam, uplink transmit power, or TA of the target neighboring cell.

[0477] Steps 806 and 807 are similar to steps 608 and 609 in the embodiment shown in Figure 6. For further details, please refer to the relevant descriptions of steps 608 and 609 in the embodiment shown in Figure 6.

[0478] In this embodiment, it should be noted that the random access procedure shown in Figure 5 may be used between a terminal device and a neighboring cell network device, i.e., it may be a contention-free random access procedure. Alternatively, a contention-based random access procedure may be used between a terminal device and a neighboring cell network device, i.e., it may be a random access procedure similar to that of the embodiment shown in Figure 5. The difference is that the preamble and random access resources in step 501 of the embodiment shown in Figure 5 are selected by the terminal device.

[0479] In this embodiment of the present application, a terminal device sends message A to a neighboring cell network device, which includes a preamble and uplink information, the preamble of which is used by the terminal device to initiate random access to a target neighboring cell. The terminal device receives a first feedback message from the serving network device, which indicates that the random access to the target neighboring cell initiated by the terminal device was successful, and further indicates the physical uplink control channel resource used by the terminal device to perform uplink communication with the target neighboring cell; or the terminal device receives a second feedback message from the serving network device, which indicates that the random access to the target neighboring cell initiated by the terminal device was successful, or that the terminal device has successfully fed back the preamble to the target neighboring cell. It can be understood that the terminal device does not need to wait for a response from the neighboring cell network device to message A, but rather waits for the serving network device's feedback message to message A, thereby helping to reduce service interruption time for the terminal device in the serving cell. Furthermore, if the terminal device receives a first or second feedback message from the serving network device, the terminal device may determine whether its random access was successful. In other words, the terminal device can determine whether its random access was successful. device Based on the feedback status, it is possible to determine whether the random access was successful. Therefore, in the technical solution of this application, a terminal device can determine the status of random access while reducing the service interruption time of terminal devices within the serving cell.

[0480] Figure 9 illustrates another embodiment of the communication method according to the embodiments of this application. Please refer to Figure 9. This method includes the following steps.

[0481] 901: The terminal device sends message 3 to a neighboring cell network device. Message 3 includes the identifier of the terminal device.

[0482] Message 3 is a message used by a terminal device to initiate random access to a target neighboring cell. The target neighboring cell is a neighboring cell of the terminal device's serving cell, the neighboring cell network device corresponds to the target neighboring cell, the signals transmitted by the neighboring cell network device cover the target neighboring cell, and the neighboring cell network device is configured to provide services to terminal devices within the target neighboring cell.

[0483] Optionally, the terminal device identifier is the identifier used by the terminal device within the serving cell, for example, the C-RNTI used by the terminal device within the serving cell.

[0484] Prior to step 901, the serving network device may indicate the identifier of a terminal device to the neighboring cell network device in advance to notify the neighboring cell network device that the terminal device is about to initiate random access to a target neighboring cell. Thus, after the neighboring cell network device receives message 3, it decides whether to request access to the terminal device indicated by the serving network device, based on the identifier of the terminal device carried in message 3 and the identifier indicated by the serving network device. The serving network device corresponds to a serving cell, and the signals transmitted by the serving network device cover that serving cell. The serving network device is configured to provide services to terminal devices within a serving cell.

[0485] 902: The neighboring cell network device sends message 4 to the serving network device. Message 4 indicates that the random access to the target neighboring cell initiated by the terminal device was successful.

[0486] In this embodiment, the random access procedure used between the terminal device and the neighboring cell network device may be the random access procedure shown in Figure 4, i.e., a contention-based random access procedure. Therefore, the neighboring cell network device selects a terminal device that has successfully performed random access and indicates that terminal device using message 4.

[0487] Optionally, message 4 includes an identifier for the terminal device, for example, an identifier used by the terminal device within the serving cell of the terminal device, for example, a C-RNTI used by the terminal device within the serving cell. This indicates that the terminal device won the conflict resolution process, i.e., that the terminal device successfully performed random access in the contention-based random access procedure.

[0488] Optionally, message 4 includes the target neighboring cell's TA.

[0489] 903: The serving network device sends message 4 to the terminal device. In response, the terminal device sends message 4 to the serving network device Message 4 is received from. Alternatively, the serving network device does not send a feedback message to the terminal device.

[0490] Optionally, after receiving message 4, the terminal device may determine that its random access was successful.

[0491] Optionally, the embodiment shown in Figure 9 further includes step 901a before step 901. Step 901a may be performed before step 901.

[0492] 901a: The terminal device sends message 1 to a neighboring cell network device. In response, the neighboring cell network device receives message 1 from the terminal device.

[0493] Message 1 contains a first preamble, which is used by the terminal device to initiate random access to target neighboring cells.

[0494] Specifically, the terminal device sends message 1 on a designated random access resource. Correspondingly, the neighboring cell network device monitors message 1 from the terminal device on the random access resource. Optionally, the neighboring cell network device monitors message 1 from the terminal device on the random access resource within a preset time window or duration used to receive message 1, as indicated by the serving network device.

[0495] Optionally, the embodiment shown in Figure 9 further includes step 901e. Step 901e may be performed before step 901a.

[0496] 901e: The serving network device sends a second scheduling signaling to the terminal device. In response, the terminal device receives the second scheduling signaling from the serving network device.

[0497] The second scheduling signaling indicates that the terminal device should initiate random access to target neighboring cells.

[0498] Optionally, a second scheduling signaling includes a random access resource, which is used by a terminal device to send message 1.

[0499] Optionally, the embodiment shown in Figure 9 further includes step 901f, which may be performed before step 901a.

[0500] 901f: The serving network device sends first information to a neighboring cell network device. In response, the neighboring cell network device receives first information from the serving network device.

[0501] The first piece of information is used by neighboring cell network devices to receive message 1.

[0502] Optionally, the first information includes at least one of the following: first indication information, the index of the first SSB of the target neighboring cell, the identifier of the terminal device, or the duration used to receive message 1. The first indication information indicates that there is a terminal device that initiates random access to the target neighboring cell by using the random access resource associated with the first SSB.

[0503] From the above explanation of the related terminology for random access resources, it can be understood that each random access resource is associated with one SSB, that is, an SSB is associated with a corresponding random access resource. Therefore, a serving network device may indicate to neighboring cell network devices the index of the first SSB to indicate the random access resource used to send message 1.

[0504] For terminal device identifiers, please refer to the relevant description in step 901.

[0505] It should be noted that steps 901e and 901f do not follow a fixed execution order. Step 901e may be performed before step 901f, or step 901f may be performed before step 901e, or steps 901e and 901f may be performed simultaneously depending on the circumstances. This is not particularly limited in this application.

[0506] Regarding Message 1, two possible feedback methods are described below.

[0507] Method 1 will be described below with reference to steps 901b and 901c. Optionally, the embodiment shown in Figure 9 further includes steps 901b and 901c. Steps 901b and 901c may be performed after step 901a.

[0508] 901b: A neighboring cell network device sends message 2 to a serving network device. In response, the serving network device receives message 2 from the neighboring cell network device.

[0509] Message 2 is a response to Message 1. Message 2 indicates whether the neighboring cell network device has received the first preamble.

[0510] For message 2, please refer to the relevant explanation for step 402 of the embodiment shown in Figure 4.

[0511] 901c: The serving network device sends message 2 to the terminal device. In response, the terminal device sends message 2 to the serving network device.

[0512] If message 2 indicates that a neighboring cell network device has successfully received the first preamble, the terminal device performs step 901. If message 2 indicates that a neighboring cell network device has failed to receive the first preamble, the serving network device may trigger the terminal device to retransmit message 1. For a relevant explanation regarding the retransmission of message 1 by the terminal device, see the previous explanation.

[0513] Note that if a terminal device does not receive message 2 from a serving network device within a preset duration or a pre-configured time window, the terminal device retransmits message 1 to the neighboring cell network device, i.e., the terminal device continues to initiate random access to the target neighboring cell by using the first preamble. Alternatively, the terminal device determines a second preamble and sends the second preamble to the neighboring cell network device.

[0514] Optionally, message 2 includes the identifier of the target neighboring cell.

[0515] In this implementation, when a terminal device sends message 1 separately to multiple neighboring cells in a relatively short time, and a neighboring cell network device responds to message 1 from a target neighboring cell, message 2 needs to carry the identifier of the target neighboring cell. This helps the terminal device determine that message 2 is the response from the target neighboring cell to message 1.

[0516] Optionally, the preset duration may be the sum of the duration of the time-domain receive window (ra-ResponseWindow) for receiving random access responses when configuring a random access resource, and a supplementary duration, which is used to compensate for the transition duration caused by the process by which a neighboring cell network device sends message 2 to a terminal device using a serving network device.

[0517] Optionally, the terminal device retransmits message 1 to neighboring cell network devices based on a pre-configured number of retransmissions and / or pre-configured power ramping parameters.

[0518] For example, a terminal device determines the transmit power to be used to retransmit message 1 based on pre-configured power ramping parameters, and then uses that transmit power to retransmit message 1 to a neighboring cell network device.

[0519] Method 2 will be described below with reference to step 901d. Optionally, the embodiment shown in Figure 9 further includes step 901d, which may be performed after step 901a.

[0520] 901d: A neighboring cell network device sends message 2 to a terminal device. In response, the terminal device receives message 2 from the neighboring cell network device.

[0521] In this implementation, the terminal device may wait for a response from a neighboring cell network device to message 1. Optionally, if the terminal device does not receive message 2 from a neighboring cell network device within a specified time period or a pre-configured time window, the terminal device may implement one of the following:

[0522] In possible implementations, the terminal device continues to use the first preamble of message 1, i.e., the terminal device retransmits message 1. For example, the terminal device retransmits message 1 based on a pre-configured power ramping parameter and / or a pre-configured number of retransmissions.

[0523] In another possible implementation, the terminal device re-selects a second preamble and then sends the second preamble to neighboring cell network devices.

[0524] Optionally, the embodiment shown in Figure 9 further includes steps 904 and 905. Steps 904 and 905 may be performed after step 903.

[0525] 904: The serving network device sends a handover command to the terminal device. In response, the terminal device receives a handover command from the serving network device.

[0526] 905: The terminal device determines at least one of the following: uplink resources, uplink transmit beam, uplink transmit power, or TA of the target neighboring cell.

[0527] Note that steps 904 and 905 are similar to steps 608 and 609 in the embodiment shown in Figure 6. For further details, see the relevant descriptions of steps 608 and 609 in the embodiment shown in Figure 6.

[0528] In this embodiment of the present application, the terminal device sends message 3 to a neighboring cell network device, which is used by the terminal device to initiate random access to a target neighboring cell, and which includes the identifier of the terminal device. The terminal device receives message 4 from the serving network device, which indicates that the random access to the target neighboring cell initiated by the terminal device was successful. Thus, the terminal device does not need to wait for a response from the neighboring cell network device to message 3, but waits for a response from the serving network device to message 3, thereby reducing the service interruption time for the terminal device in the serving cell. Furthermore, the terminal device receives message 4 from the serving network device, which indicates that the random access to the target neighboring cell initiated by the terminal device was successful. Thus, the terminal device can determine that the random access was successful based on the feedback status of the serving network device. Thus, in the technical solution of the present application, the terminal device can determine the access status of the random access while reducing the service interruption time for the terminal device in the serving cell.

[0529] It can be understood that the terminology and related technologies of the embodiments may be referenced to one another. However, it should be noted that the definitions of technical terms that have the same name in the different embodiments described above may differ, and in particular, technical terms should be understood in reference to the embodiment in which they are used.

[0530] The following describes the communication device provided in the embodiment of this application.

[0531] Figure 10 is a diagram showing the structure of a communication device according to an embodiment of the present application. Please refer to Figure 10. The communication device may be configured to perform the processing carried out by the terminal device in the embodiments shown in Figures 6, 8, and 9. For further details, please refer to the relevant descriptions of the method embodiments described above.

[0532] The communication device 1000 includes a transceiver module 1001. Optionally, the communication device 1000 further includes a processing module 1002.

[0533] The processing module 1002 is configured to process data. The transceiver module 1001 may implement the corresponding communication function. The transceiver module 1001 is sometimes called a communication interface or communication module.

[0534] Optionally, the communication device 1000 may further include a storage module. The storage module may be configured to store instructions and / or data. The communication device implements the method embodiment described above, since the processing module 1002 can read instructions and / or data from the storage module.

[0535] Communication equipment Place 1 000 may be configured to perform operations performed by the terminal device of the method embodiment described above. The communication device 1000 may be a terminal device or a component that can be configured within the terminal device. The processing module 1002 is configured to perform processing-related operations on the terminal device side of the method embodiment described above. The transceiver module 1001 is configured to perform receiving-related operations on the terminal device side of the method embodiment described above.

[0536] Optionally, the transceiver module 1001 may include a transmit module and a receive module. The transmit module is configured to perform the transmit operation of the method embodiment described above. The receive module is configured to perform the receive operation of the method embodiment described above.

[0537] It should be noted that the communication device 1000 may include a transmitting module but not a receiving module. Alternatively, the communication device 1000 may include a receiving module but not a transmitting module. This may be determined in particular depending on whether the aforementioned solution implemented by the communication device 1000 includes transmitting and receiving actions.

[0538] Optionally, the communication device 1000 is configured to perform an action carried out by the terminal device in any one of the method embodiments shown in Figures 6, 8, and 9.

[0539] For example, the communication device 1000 is configured to perform actions carried out by the terminal device in the embodiment shown in Figure 6.

[0540] The transceiver module 1001 is configured to send a random access request to a neighboring cell network device, which is used to initiate random access to a target neighboring cell, which is a neighboring cell of the serving cell of the communication device 1000. The communication device 1000 retransmits the random access request to the neighboring cell network device if it does not receive a feedback message about the random access request from the serving network device, or if it receives at least one of a first feedback message or a first scheduling signaling from the serving network device, the first feedback message indicating that the random access of the communication device has failed, and the first scheduling signaling is used to schedule the communication device to retransmit the random access request.

[0541] For example, the communication device 1000 is configured to perform actions carried out by the terminal device in the embodiment shown in Figure 8.

[0542] Transceiver module 1001 The system is configured to send message A to a neighboring cell network device, which includes a preamble and uplink information, the preamble being used by the communication device 1000 to initiate random access to a target neighboring cell, the target neighboring cell being a neighboring cell of the serving cell of the communication device 1000; to receive a first feedback message from the serving network device, which indicates that the random access to the target neighboring cell initiated by the communication device 1000 was successful, and further indicates the physical uplink control channel resource used by the communication device 1000 to perform uplink communication with the target neighboring cell; or to receive a second feedback message from the serving network device, which indicates either that the random access to the target neighboring cell initiated by the communication device 1000 was successful, or that the communication device 1000 successfully fed back the preamble to the target neighboring cell.

[0543] For example, the communication device 1000 is shown in Figure 9 It is configured to perform actions performed by the terminal device of the embodiment shown.

[0544] The transceiver module 1001 is configured to send message 3 to a neighboring cell network device, which is used by the communication device 1000 to initiate random access to a target neighboring cell, the target neighboring cell being a neighboring cell of the serving cell of the communication device 1000, and message 3 containing the identifier of the communication device 1000; and to receive message 4 from the serving network device, which indicates that the random access to the target neighboring cell initiated by the communication device 1000 was successful.

[0545] It should be understood that the specific processes by which the module performs the corresponding processes described above are described in detail in the method embodiments described above. For the sake of brevity, the details will not be described again herein.

[0546] The processing module 1002 of the above-described embodiment may be implemented by at least one processor or processor-related circuitry. The transceiver module 1001 may be implemented by a transceiver or transceiver-related circuitry. The transceiver module 1001 may also be called a communication module or communication interface. The storage module may be implemented by at least one memory.

[0547] Figure 11 shows another structure of the communication device according to an embodiment of the present application. Please refer to Figure 11. The communication device may be configured to perform the processing carried out by the serving network device of the embodiment shown in Figures 6, 8, and 9. For further details, please refer to the relevant description of the method embodiment described above.

[0548] The communication device 1100 includes a transceiver module 1101. Optionally, the communication device 1100 further includes a processing module 1102. The transceiver module 1101 can perform corresponding communication functions. The processing module 1102 is configured to process data. The transceiver module 1101 is sometimes referred to as a communication interface or communication module.

[0549] Optionally, the communication device 1100 may further include a storage module. The storage module may be configured to store instructions and / or data. The communication device implements the method embodiment described above, as the processing module 1102 can read instructions and / or data from the storage module.

[0550] Communication equipment Place 1100 may be configured to perform operations performed by the serving network device of the method embodiment described above. The communication device 1100 may be a serving network device or a component that can be configured within the serving network device. The transceiver module 1101 is configured to perform receive-related operations on the serving network device side of the method embodiment described above, and the processing module 1102 is configured to perform processing-related operations on the serving network device side of the method embodiment described above.

[0551] Optionally, the transceiver module 1101 may include a transmit module and a receive module. The transmit module is configured to perform the transmit operation of the method embodiment described above. The receive module is configured to perform the receive operation of the method embodiment described above.

[0552] It should be noted that the communication device 1100 may include a transmitting module but not a receiving module. Alternatively, the communication device 1100 may include a receiving module but not a transmitting module. This may be determined in particular depending on whether the aforementioned solution implemented by the communication device 1100 includes transmitting and receiving actions.

[0553] Optionally, the communication device 1100 is configured to perform actions carried out by the serving network device in the method embodiments shown in Figures 6, 8, and 9.

[0554] For example, the communication device 1100 is configured to perform actions carried out by the serving network device in the embodiment shown in Figure 6.

[0555] The transceiver module 1101 is configured to send at least one of the first feedback message or the first scheduling signaling to the terminal device if the communication device 1100 does not receive a feedback message from a neighboring cell network device regarding a random access request from the terminal device, or if the communication device 1100 receives a third feedback message from a neighboring cell network device and the third feedback message indicates that the neighboring cell network device did not receive a random access request; or to skip sending a feedback message to the terminal device. La A random access request is used by a terminal device to request access to a target neighboring cell, which is a neighboring cell of the terminal device's serving cell; a first feedback message indicates that the terminal device's random access has failed, and a first scheduling signaling is used to schedule the terminal device to resend the random access request.

[0556] For example, the communication device 1100 is configured to perform actions carried out by the serving network device in the embodiment shown in Figure 8.

[0557] The transceiver module 1101 is configured such that, when the communication device 1100 receives a successful random access response message from a neighboring cell network device, it sends a first feedback message to the terminal device, which indicates that a random access to a target neighboring cell initiated by the terminal device was successful, the target neighboring cell being a neighboring cell of the terminal device's serving cell, and the first feedback message further indicates the PUCCH resource used by the terminal device to perform uplink transmission with the target neighboring cell; or, when the communication device 1100 receives a fallback random access response message from a neighboring cell network device, it sends a second feedback message to the terminal device, which is configured such that the second feedback message 1101 indicates either that a random access to a target neighboring cell initiated by the terminal device was successful, or that the terminal device has successfully fed back a preamble to the target neighboring cell.

[0558] For example, the communication device 1100 is configured to perform actions carried out by the serving network device in the embodiment shown in Figure 9.

[0559] The transceiver module 1101 is configured to receive message 4 from a neighboring cell network device, which indicates that a random access to a target neighboring cell initiated by the terminal device was successful and that the target neighboring cell is a neighboring cell of the terminal device's serving cell; and to send message 4 back to the terminal device.

[0560] It should be understood that the specific processes by which the module performs the corresponding processes described above are described in detail in the method embodiments described above. For the sake of brevity, the details will not be described again herein.

[0561] The processing module 1102 of the above-described embodiment may be implemented by at least one processor or processor-related circuitry. The transceiver module 1101 may be implemented by a transceiver or transceiver-related circuitry. The transceiver module 1101 may also be called a communication module or communication interface. The storage module may be implemented by at least one memory.

[0562] Figure 12 shows yet another structure of the communication device according to an embodiment of the present application. Please refer to Figure 12. The communication device may be configured to perform the processing carried out by the neighbor cell network device of the embodiment shown in Figures 6, 8, and 9. For further details, please refer to the relevant description of the method embodiment described above.

[0563] The communication device 1200 includes a transceiver module 1201. Optionally, the communication device 1200 further includes a processing module 1202. The transceiver module 1201 can perform corresponding communication functions. The processing module 1202 is configured to process data. The transceiver module 1201 is sometimes referred to as a communication interface or communication module.

[0564] Optionally, the communication device 1200 may further include a storage module. The storage module may be configured to store instructions and / or data. The communication device implements the method embodiment described above, as the processing module 1202 can read instructions and / or data from the storage module.

[0565] Communication equipment Place 1200 may be configured to perform operations performed by the neighbor cell network device in the method embodiment described above. The communication device 1200 may be a neighbor cell network device or a component that can be configured within a neighbor cell network device. The transceiver module 1201 is configured to perform reception-related operations on the neighbor cell network device side in the method embodiment described above, and the processing module 1202 is configured to perform processing-related operations on the neighbor cell network device side in the method embodiment described above.

[0566] Optionally, the transceiver module 1201 may include a transmit module and a receive module. The transmit module is configured to perform the transmit operation of the method embodiment described above. The receive module is configured to perform the receive operation of the method embodiment described above.

[0567] It should be noted that the communication device 1200 may include a transmitting module but not a receiving module. Alternatively, the communication device 1200 may include a receiving module but not a transmitting module. This may be determined in particular depending on whether the aforementioned solution implemented by the communication device 1200 includes transmitting and receiving actions.

[0568] Optionally, the communication device 1200 is configured to perform actions carried out by the neighbor cell network device in the method embodiments shown in Figures 6, 8, and 9.

[0569] For example, the communication device 1200 is configured to perform actions carried out by the neighbor cell network device in the embodiment shown in Figure 6.

[0570] The transceiver module 1201 either sends a third feedback message to the serving network device or skips sending a feedback message to the serving network device if the communication device 1200 does not receive a random access request from the terminal device. A third feedback message indicates that the communication device 1200 has not received a random access request, which is used by a terminal device to request access to a target neighboring cell, and the target neighboring cell is a neighboring cell of the terminal device's serving cell.

[0571] For example, the communication device 1200 is configured to perform actions carried out by the neighbor cell network device in the embodiment shown in Figure 8.

[0572] The transceiver module 1201 is configured such that, if the communication device 1200 successfully receives message A sent by the terminal device, it sends a successful random access response message to the serving network device, which includes the terminal device's preamble and uplink information, the preamble of which is used by the terminal device to initiate random access to a target neighbor cell, the target neighbor cell being a neighbor cell of the terminal device's serving cell; or, if the communication device 1200 successfully receives only the preamble in message A of the terminal device, it sends a fallback random access response message to the serving network device.

[0573] For example, the communication device 1200 is configured to perform actions carried out by the neighbor cell network device in the embodiment shown in Figure 9.

[0574] The transceiver module 1201 is configured to receive message 3 from a terminal device, which is message 3 used by the terminal device to initiate random access to a target neighbor cell, which is a neighbor cell of the terminal device's serving cell, and which includes the identifier of the terminal device; and to send message 4 to the serving network device, which message 4 indicates that the random access to the target neighbor cell initiated by the terminal device was successful.

[0575] It should be understood that the specific processes by which the module performs the corresponding processes described above are described in detail in the method embodiments described above. For the sake of brevity, the details will not be described again herein.

[0576] The processing module 1202 of the above-described embodiment may be implemented by at least one processor or processor-related circuitry. The transceiver module 1201 may be implemented by a transceiver or transceiver-related circuitry. The transceiver module 1201 may also be called a communication module or communication interface. The storage module may be implemented by at least one memory.

[0577] Embodiments of this application further provide a communication device 1300. Please refer to Figure 13. The communication device 1300 includes a processor 1310. The processor 1310 is coupled to a memory 1320. The memory 1320 is configured to store computer programs or instructions and / or data. The processor 1310 is configured to execute computer programs or instructions and / or data stored in the memory 1320, so that the method of the above-described embodiment is carried out.

[0578] Optionally, the communication device 1300 includes one or more processors 1310.

[0579] Optionally, the communication device 1300 may further include a memory 1320, as shown in Figure 13.

[0580] The communication device 1300 may optionally include one or more memories 1320.

[0581] Optionally, the memory 1320 and processor 1310 may be integrated or located separately.

[0582] Optionally, the communication device 1300 may further include a transceiver 1330, as shown in Figure 13. The transceiver 1330 is configured to receive and / or transmit signals. For example, the processor 1310 is configured to control the transceiver 1330 to receive and / or transmit signals.

[0583] In the solution, the communication device 1300 is configured to implement the operations performed by the terminal device in the method embodiment described above.

[0584] For example, the processor 1310 is configured to implement processing-related operations performed by the terminal device of the method embodiment described above, and the transceiver 1330 is configured to implement receiving / transmitting-related operations performed by the terminal device of the method embodiment described above.

[0585] In an alternative solution, the communication device 1300 is configured to implement the operations performed by the neighbor cell network device in the method embodiment described above.

[0586] For example, the processor 1310 is configured to implement processing-related operations performed by the neighbor cell network device of the method embodiment described above, and the transceiver 1330 is configured to implement receiving / transmitting-related operations performed by the neighbor cell network device of the method embodiment described above.

[0587] In yet another solution, the communication device 1300 is configured to implement the operations performed by the serving network device in the method embodiment described above.

[0588] For example, the processor 1310 is configured to implement processing-related operations performed by the serving network device of the method embodiment described above, and the transceiver 1330 is configured to implement receiving / transmitting-related operations performed by the serving network device of the method embodiment described above.

[0589] This application further provides a communication device 1400, which may be a terminal device, a processor of a terminal device, or a chip. The communication device 1400 may be configured to perform the operations performed by the terminal device of the method embodiment described above.

[0590] When the communication device 1400 is a terminal device, Figure 14 shows a simplified structure of the terminal device. As shown in Figure 14, the terminal device includes a processor, memory, and a transceiver. The memory may store computer program code. The transceiver includes a transmitter 1431, a receiver 1432, a high-frequency circuit (not shown), an antenna 1433, and an input / output device (not shown).

[0591] The processor is primarily configured to process communication protocols and data, control terminal devices to execute software programs, process data within software programs, and do the same. Memory is primarily configured to store software programs and data. High-frequency circuits are primarily configured to perform conversions between baseband signals and high-frequency signals and to process high-frequency signals. Antennas are primarily configured to receive and transmit high-frequency signals in the form of electromagnetic waves. Input / output devices, such as touchscreens, display screens, or keyboards, are primarily configured to receive data entered by the user and output that data to the user. Note that some types of terminal devices may not have input / output devices.

[0592] When data needs to be transmitted, the processor performs baseband processing on the data to be transmitted, then outputs the baseband signal to a high-frequency circuit, which performs high-frequency processing on the baseband signal and then transmits the high-frequency signal to the outside via an antenna in the form of an electromagnetic wave. When data is transmitted to a terminal device, the high-frequency circuit receives the high-frequency signal via the antenna, converts the high-frequency signal into a baseband signal, and outputs the baseband signal to the processor. The processor converts the baseband signal into data and processes the data. For simplicity of explanation, Figure 14 shows only one memory, one processor, and one transceiver. Actual terminal device products may have one or more processors and one or more memories. Memory is sometimes called a storage medium or storage device. Memory may be located independently of the processor or integrated with the processor. This is not limited to the embodiments of this application.

[0593] In the embodiments of this application, the antenna and high-frequency circuit having transmitting and receiving functions may be considered as a transceiver module of a terminal device, and the processor having processing functions may be considered as a processing module of a terminal device.

[0594] As shown in Figure 14, the terminal device includes a processor 1410, memory 1420, and transceiver 1430. The processor 1410 may also be called a processing unit, processing board, processing module, or processing unit. The transceiver 1430 may also be called a transceiver unit, transceiver machine, or transceiver device.

[0595] Optionally, any component within the transceiver 1430 configured to implement a receiving function may be considered a receiving module, and any component within the transceiver 1430 configured to implement a transmitting function may be considered a transmitting module. In other words, the transceiver 1430 includes a receiver and a transmitter. The transceiver may also be referred to as a transceiver unit, transceiver module, transceiver circuit, etc. The receiver may also be referred to as a receiver, receiving module, receiver circuit, etc. The transmitter may also be referred to as a transmitter, transmitting module, transmitter circuit, etc.

[0596] The processor 1401 is configured to perform processing actions on the terminal device side of the embodiments shown in Figures 6, 8, and 9, and the transceiver 1430 is configured to perform receiving and transmitting actions on the terminal device side of the embodiments shown in Figures 6, 8, and 9.

[0597] Please understand that Figure 14 is merely an example, not an exhaustive one. The terminal device, including the transceiver module and processing module, does not necessarily have to depend on the structure shown in Figure 10 or Figure 14.

[0598] When the communication device 1400 is a chip, the chip includes a processor, memory, and a transceiver. The transceiver may be an input / output circuit or a communication interface. The processor may be a processing module, a microprocessor, or an integrated circuit on the chip. The transmission operation performed by the terminal device of the method embodiment described above may be understood as an output of the chip, and the reception operation performed by the terminal device of the method embodiment described above may be understood as an input of the chip.

[0599] This application further provides a communication device 1500, which may be a network device or a chip. The communication device 1500 may be configured to perform operations performed by a neighbor cell network device or a serving network device in the method embodiments of Figures 6, 8, and 9.

[0600] When the communication device 1500 is a network device, such as a base station, Figure 15 shows a simplified structure of the base station. The base station includes components 1510, 1520, and 1530. Component 1510 is mainly configured to perform baseband processing, control the base station, and do the same. Component 1510 is typically the control center of the base station, sometimes referred to as a processor, and is configured to control the base station to perform processing operations on the network device side of the method embodiment described above. Component 1520 is mainly configured to store computer program code and data. Component 1530 is mainly configured to receive and transmit high-frequency signals and to implement conversion between high-frequency signals and baseband signals. Component 1530 is sometimes referred to as a transceiver module, transceiver machine, transceiver circuit, or transceiver. The transceiver module as component 1530 may also be referred to as a transceiver machine, transceiver, etc., and may include an antenna 1533 and a high-frequency circuit (not shown). The high-frequency circuit is mainly configured to perform high-frequency processing. Optionally, components configured to implement the receiving function of component 1530 may be considered receivers, and components configured to implement the transmitting function may be considered transmitters. In other words, component 1530 includes receiver 1532 and transmitter 1531. Receivers may also be called receiving modules, receivers, receiver circuits, etc., and transmitters may be called transmitting modules, transmitters, transmitter circuits, etc.

[0601] Components 1510 and 1520 may include one or more circuit boards, each of which may include one or more processors and one or more memories. The processors are configured to read and execute programs from memory, implement baseband processing functions, and control base stations. If there are multiple circuit boards, they may be connected to each other to increase processing power. In an optional implementation, multiple circuit boards may share one or more processors, or multiple circuit boards may share one or more memories, or multiple circuit boards may simultaneously share one or more processors.

[0602] For example, in the implementation shown in Figures 6, 8, and 9, the transceiver module of component 1530 is configured to implement receive / transmit related processing performed by the neighbor cell network device or serving network device. The processor of component 1510 is configured to perform processing related processing performed by the neighbor cell network device or serving network device in the embodiment shown in Figures 6, 8, and 9.

[0603] Figure 15 is merely an example, not an exhaustive one, and it should be understood that network devices, including processors, memory, and transceivers, do not necessarily have to depend on the configuration shown in Figures 11, 12, or 15.

[0604] When the communication device 1500 is a chip, this chip includes a transceiver, memory, and a processor. The transceiver may be an input / output circuit or a communication interface. The processor is a processor, a microprocessor, or an integrated circuit integrated on the chip. Neighboring cell network device or serving The transmission operation performed by the network device may be understood as the output of the chip, and the reception operation performed by the neighbor cell network device or serving network device in the method embodiment described above may be understood as the input of the chip.

[0605] Embodiments of this application further provide a computer-readable storage medium for storing computer instructions used to implement the method implemented by a terminal device, a neighbor cell network device, or a serving network device of the method embodiments described above.

[0606] For example, when a computer program is executed by a computer, the computer is enabled to implement the methods carried out by the terminal device, neighbor cell network device, or serving network device of the aforementioned method embodiments.

[0607] Embodiments of this application further provide a computer program product including instructions. When the instructions are executed by a computer, the computer is enabled to implement the method as performed by a terminal device, a neighbor cell network device, or a serving network device of the aforementioned method embodiment.

[0608] Embodiments of this application further provide a communication system, which includes a terminal device of the above-described embodiment, a neighbor cell network device of the above-described embodiment, and a serving network device of the above-described embodiment.

[0609] Embodiments of this application further provide a chip device including a processor configured to call computer programs or computer instructions stored in memory, so that the processor implements the methods of the embodiments shown in Figures 6, 8, and 9.

[0610] In possible implementations, the input of the chip device corresponds to one of the receiving operations shown in the embodiments of Figures 6, 8, and 9, and the output of the chip device corresponds to one of the transmitting operations shown in the embodiments of Figures 6, 8, and 9.

[0611] Optionally, the processor is coupled to memory via an interface.

[0612] Optionally, the chip device may further include memory, which stores computer programs or computer instructions.

[0613] The processors mentioned above are general-purpose central processing units, microprocessors, and application-specific integrated circuits configured to control program execution in the manner provided in any one of the embodiments shown in Figures 6, 8, and 9. (A SIC) or one or more integrated circuits. Any memory mentioned above is read-only memory. (R OM), another type of static memory device capable of storing static information and instructions, random access memory. (R It can be something like AM.

[0614] Those skilled in the art will readily understand that, for the sake of a simple and concise explanation, they should refer to the corresponding method embodiments provided above for a description of the relevant content and beneficial effects of any one of the communication devices provided above. Further details are not described again herein.

[0615] In this application, a communication device or network device may include a hardware layer, an operating system layer running on top of the hardware layer, and an application layer running on top of the operating system layer. The hardware layer is a central processing unit. (C PU), memory management device (M The operating system layer may include hardware such as MU and memory (also called main memory). The operating system layer may be any one or more computer operating systems that implement service processing by using processes, such as the Linux operating system, Unix operating system, Android operating system, iOS operating system, or Windows operating system. The application layer may include applications such as browsers, address books, word processing software, and instant messaging software.

[0616] Those skilled in the art will clearly understand that, for the sake of a simple and concise explanation, detailed working procedures of the aforementioned systems, apparatus, and modules should be referred to the corresponding procedures in the aforementioned method embodiments, and such details are not described again herein.

[0617] In some embodiments provided in this application, it should be understood that the disclosed systems, apparatus, and methods may be implemented in other ways. For example, the apparatus embodiments described above are merely examples. For example, the division of modules is merely a logical functional division. In actual implementations, other division methods are possible. For example, multiple modules or components may be combined or integrated to form a separate system, or some features may be ignored or not implemented. In addition, the mutual coupling, direct coupling, or communication connection presented or discussed may be implemented through some interfaces. Indirect coupling or communication connection between apparatus or modules may be implemented in electronic, mechanical, or other forms.

[0618] Modules described as separate components may or may not be physically separated, and components shown as modules may or may not be physical modules, may be located in one place, or may be distributed across multiple network modules. Some or all of the modules may be selected as required in practice to achieve the objectives of the solution of the embodiment.

[0619] In addition, the functional modules in the embodiments of this application may be integrated into a single processing module, or each module may exist physically independently, or two or more modules may be integrated into a single module. The integrated module may be implemented in hardware form or in the form of a software functional module.

[0620] When an integrated module is implemented in the form of a software function module and sold or used as an independent product, the integrated unit may be stored on a computer-readable storage medium. Based on such understanding, a portion that essentially contributes to the technical solution of this application, or all or part of that technical solution, may be implemented in the form of a software product. The computer software product is stored on a storage medium and includes several instructions that enable a computer device (which may be a personal computer, server, or network device, etc.) to perform all or part of the processing of the methods of the embodiments of this application. The aforementioned storage medium includes any medium capable of storing program code, such as a USB flash disk, removable hard disk, read-only memory, random access memory, magnetic disk, or optical disk.

[0621] In conclusion, the embodiments described above are merely for illustrative purposes and do not limit the present application. Although the present application has been described in detail with respect to the embodiments described above, those skilled in the art will understand that it is possible to further modify the technical solutions described in the embodiments described above, or to make equivalent substitutions to some of these technical features, without departing from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method of communication, The steps include: sending a random access request to a candidate network device via a terminal device, wherein the random access request is used to initiate random access to a candidate cell; If the terminal device does not receive a feedback message from the serving network device regarding the random access request, or if the terminal device receives at least one of a first feedback message or a first scheduling signaling from the serving network device, the terminal device retransmits the random access request to the candidate network device, wherein the first feedback message indicates that the random access by the terminal device failed, and the first scheduling signaling is used to schedule the terminal device to retransmit the random access request. A communication method that includes this.

2. Steps in which the terminal device determines that the random access of the terminal device has been successful, provided that the terminal device receives at least one of a second feedback message or first indication information from the serving network device, wherein the second feedback message indicates that the candidate network device has successfully received the random access request, and the first indication information indicates that the terminal device should not retransmit the random access request to the candidate network device. The method according to claim 1, further comprising:

3. The method according to claim 2, wherein the second feedback message further includes at least one of the uplink timing advance of the candidate cell, an identifier assigned to the terminal device by the candidate cell, or an uplink resource assigned to the terminal device by the candidate cell.

4. The step of the terminal device resending the random access request to the candidate network device is: The terminal device retransmits the random access request to the candidate network device based on a preset number of retransmissions and / or preset power ramping parameters. The method according to claim 1, including the method described in claim 1.

5. The first feedback message or the first scheduling signaling further includes power ramping parameters, The step of the terminal device resending the random access request to the candidate network device is: The terminal device retransmits the random access request to the candidate network device based on the power ramping parameters. The method according to claim 1, including the method described in claim 1.

6. The step of the terminal device receiving a handover command from the serving network device, wherein the handover command indicates that the terminal device should hand over to the candidate cell. The method according to any one of claims 1 to 5, further comprising:

7. After the terminal device receives the handover command from the serving network device, the method: The terminal device determines at least one of the following: uplink resources, uplink transmit beam, uplink transmit power, or uplink timing advance of the candidate cell. It further includes, The method according to claim 6, wherein the uplink resource is used by the terminal device to communicate with the candidate cell, the uplink transmit beam is a beam used by the terminal device to perform uplink transmission with the candidate cell, the uplink transmit power is power used by the terminal device to perform uplink transmission with the candidate cell, and the uplink timing advance of the candidate cell is a timing advance used by the terminal device to transmit an uplink signal to the candidate cell.

8. The step of determining the uplink resource using the terminal device is: The terminal device uses a pre-configured individual physical uplink control channel PUCCH resource or a pre-configured set grant physical uplink shared channel PUSCH resource as the uplink resource, or A step in which the terminal device determines the uplink resource by using a handover command, wherein the handover command includes the uplink resource, or A step of monitoring a second scheduling signaling transmitted by a candidate network device on a pre-configured time-frequency resource by the terminal device, wherein the second scheduling signaling indicates the uplink resource. The method according to claim 7, including the method described in claim 7.

9. Prior to the step of monitoring the second scheduling signaling transmitted by the candidate network device by the terminal device on the aforementioned pre-configured time-frequency resource, the method: A step in which the terminal device determines the pre-configured time-frequency resources based on the search space and the control resource set, wherein the search space and the control resource set are configured for the terminal device by the candidate network device for the terminal device for cell handover, or the search space and the control resource set are configured for the terminal device by the serving network device. The method according to claim 8, further comprising:

10. A step in which the terminal device sends indication information to the candidate network device by using the uplink resource, wherein the indication information indicates that the terminal device has handed over to the candidate network device. The method according to claim 8, further comprising:

11. The step of determining the uplink transmission power using the aforementioned terminal device is: The terminal device determines the path loss between the candidate network device and the terminal device based on a first path loss reference signal, and the terminal device determines the uplink transmit power based on the path loss, or The terminal device uses the transmission power for sending the random access request as the first transmission power. The method according to claim 7 or 8, including the method described in claim 7 or 8.

12. If the handover command further includes the activated transmit setting indicator TCI state of the candidate cell, the first path loss reference signal is the path loss reference signal associated with the activated TCI state, or If the handover command further includes the deactivated TCI state of the candidate cell, the first path loss reference signal is a synchronization signal and a physical broadcast channel block SSB associated with the random access resource used by the terminal device to send the random access request, or If the handover command further includes a reference signal for the candidate cell, the first path loss reference signal is the reference signal for the candidate cell. The method according to claim 8.

13. The handover command further includes a power control parameter associated with the activated TCI state of the candidate cell, or a power control parameter associated with the deactivated TCI state of the candidate cell, and the terminal device determines the uplink transmit power based on the path loss, The terminal device determines the uplink transmit power based on the path loss and the power control parameters. The method according to any one of claims 8 to 12, including the method described in any one of claims 8 to 12.

14. The step of determining the uplink timing advance of the candidate cell using the terminal device is: If the handover command includes the uplink timing advance of the candidate cell, the terminal device may take the following steps: use the uplink timing advance in the handover command as the uplink timing advance of the candidate cell, or If the handover command does not include the uplink timing advance of the candidate cell, the terminal device defaults to assuming that the uplink timing advance of the candidate cell is equal to 0, or If the handover command does not include the uplink timing advance of the candidate cell, the terminal device may use the uplink timing advance carried in the second feedback message as the uplink timing advance of the candidate cell, or If the handover command includes an uplink timing advance indication, and the uplink timing advance indication indicates that the terminal device should determine the uplink timing advance of the candidate cell, the terminal device uses the uplink timing advance of the candidate cell determined by the terminal device as the uplink timing advance of the candidate cell. The method according to claim 7, including the method described in claim 7.

15. The step of determining the uplink transmit beam using the aforementioned terminal device is: If the handover command includes a TCI state indicated by the candidate network device for the terminal device, the terminal device may determine the uplink transmit beam based on the TCI state indicated in the handover command, or If the TCI state indicated in the handover command is a downlink TCI state, the terminal device determines the uplink transmit beam based on the received beam of the SSB associated with the random access resource used to send the random access request. The method according to claim 7, including the method described in claim 7.

16. The method according to any one of claims 1 to 15, wherein the first scheduling signaling includes second indication information, the second indication information indicates that the terminal device should retransmit the random access request.

17. The first scheduling signaling further includes at least one of the third indication information or power ramping parameters, The third indication information indicates whether the terminal device should increase power to send the random access request, and the power ramping parameter includes a power ramping value or power ramping stage. The method according to any one of claims 1 to 16.

18. The steps include: receiving a fourth indication information from the serving network device via the terminal device, wherein the fourth indication information indicates that the terminal device should not wait for a feedback message from the candidate network device regarding the random access request; The terminal device continues to communicate with the serving network device without waiting for the feedback message from the candidate network device regarding the random access request. The method according to any one of claims 1 to 17, further comprising:

19. Before the step of the terminal device sending the random access request to the candidate network device, the method: The step of the terminal device receiving downlink control information DCI from the serving network device, wherein the DCI indicates that the terminal device should send the random access request to the candidate network device, and the DCI further indicates that the terminal device should receive the feedback message from the serving network device regarding the random access request. The method according to any one of claims 1 to 18, further comprising:

20. Before the step of the terminal device sending the random access request to the candidate network device, the method: The terminal device receives a third scheduling signaling from the serving network device, the third scheduling signaling being used to schedule the terminal device to initiate the random access request to the candidate cell. The method according to any one of claims 1 to 18, further comprising:

21. The method according to claim 20, wherein the first scheduling signaling includes first resource configuration information, the third scheduling signaling includes second resource configuration information, the first resource configuration information differs from the second resource configuration information, the third scheduling signaling is carried in a DCI, the DCI indicates a PRACH resource, and the DCI is used by the terminal device to initially transmit the random access request.

22. The third scheduling signaling is carried in the DCI, which includes a first field. If the value of the first field is the first value, the DCI indicates that there is a feedback message for the random access request of the terminal device, and the terminal device waits for the feedback message, or If the value of the first field is the second value, the DCI indicates that there is no feedback message for the random access request from the terminal device, and the terminal device does not need to wait for the feedback message. The method according to claim 20.

23. A method of communication, If a candidate network device does not receive a random access request from a terminal device, the candidate network device sends a third feedback message to the serving network device, or the candidate network device skips sending a feedback message to the serving network device, wherein the third feedback message indicates that the candidate network device did not receive the random access request, and the random access request is used by the terminal device to request access to the candidate cell. Correspondingly, the serving network device sends at least one of a first feedback message or a first scheduling signaling to the terminal device, or the serving network device skips sending a feedback message to the terminal device, wherein the first feedback message indicates that the random access of the terminal device has failed, and the first scheduling signaling is used to schedule the terminal device to retransmit the random access request. A communication method that includes this.

24. If the candidate network device receives a random access request from the terminal device, the candidate network device sends a fourth feedback message to the serving network device, wherein the fourth feedback message indicates that the candidate network device has successfully received the random access request. Correspondingly, the serving network device sends at least one of a second feedback message or first indication information to the terminal device, or the serving network device skips sending a feedback message to the terminal device, wherein the second feedback message indicates that the random access by the terminal device was successful, and the first indication information indicates that the terminal device does not retransmit the random access request to the candidate network device. The method according to claim 23, further comprising:

25. A communication device comprising a transceiver module, The transceiver module is configured to perform the receiving and transmitting operations according to any one of claims 1 to 22, or The transceiver module is configured to perform the receiving and transmitting operations according to the method described in claim 23 or 24. Communication device.

26. The communication device according to claim 25, wherein the communication device further comprises a processing module, and the transceiver module is configured to perform the receiving and transmitting operations in the method according to any one of claims 1 to 22, the processing module is configured to perform the processing operations described in any one of claims 1 to 22.

27. A communication device, wherein the communication device is Memory configured to store computer instructions, A processor and a computer configured to execute a computer program stored in the memory or a computer instruction, thereby enabling the communication device to carry out the method according to any one of claims 1 to 22, or the method according to claim 23 or 24. A communication device equipped with the following features.

28. A communication device comprising a processor, wherein the processor is configured to carry out the method according to any one of claims 1 to 22, or the method according to claim 23 or 24.

29. A computer-readable storage medium that stores a computer program, and when the computer program is executed by a communication device, enables the communication device to carry out the method according to any one of claims 1 to 22.

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