Communication method, device and computer-readable storage medium

Abstract

The present application provides a communication method, apparatus, and computer-readable storage medium. The method includes: determining that after the terminal device switches from the second cell to the first cell, the carrier for uplink transmission of the terminal device in the first cell is the first carrier; wherein the first carrier and the second carrier belong to the same frequency band, and the second carrier is the carrier of the terminal device in the second cell. Through the technical solution provided by the present application, the terminal device can realize uplink transmission in the first cell without random access. Therefore, the solution provided by the present application can effectively avoid the delay and interruption problems that may occur during the switching process of the terminal device to the first cell that requires random access, and can improve the efficiency of communication.

Description

Technical Field

[0001] The present application relates to the field of wireless communication technologies, and in particular to a communication method, device, and computer-readable storage medium. Background Art

[0002] In a wireless communication system, when a user equipment (UE) is in a service-connected state and maintains service, it moves from one cell to another. In order to ensure the continuity of UE communication, a handover is required.

[0003] In the new radio access technology (NR) system, during a handover, the UE needs to perform random access to the target cell to obtain the timing advance (TA) value after the UE switches to the target cell, thereby completing the UE's uplink synchronization in the target cell. However, the handover process requiring random access to the target cell may cause delays and interruptions, thereby reducing communication efficiency. Summary of the Invention

[0004] The present application provides a communication method, device, and computer-readable storage medium, which can improve communication efficiency.

[0005] In a first aspect, the present application provides a communication method, which can be applied to a terminal device or to a module (e.g., a chip) in the terminal device. The following description takes application to the terminal device as an example. The communication method may include: determining that after the terminal device switches from the second cell to the first cell, the carrier for uplink transmission by the terminal device in the first cell is a first carrier; wherein the first carrier and the second carrier belong to the same frequency band, and the second carrier is the carrier of the terminal device in the second cell.

[0006] In the solution provided in this application, before a terminal device switches, it communicates with a second network device in a second cell. The second network device can send downlink transmissions to the terminal device, and the terminal device can send uplink transmissions on a second carrier to a fourth network device. The fourth network device is a network device that can receive uplink transmissions sent by the terminal device on the second carrier. The fourth network device then sends the uplink transmission data to the second network device. For example, the fourth network device can send the uplink transmission data to the second network device via a backhaul. If the second network device is the fourth network device, that is, the second carrier and the second cell are co-located, or the second carrier and the second network device are co-located, then the terminal device can directly send uplink transmissions to the second network device on the second carrier. After the terminal device switches, it communicates with the first network device in the first cell. The first network device can send downlink transmissions to the terminal device, and the terminal device can send uplink transmissions on the first carrier to a fifth network device. The fifth network device is a network device that can receive uplink transmissions sent by the terminal device on the first carrier. The fifth network device then sends the uplink transmission data to the first network device. For example, the fifth network device can send the uplink transmission data to the first network device via a backhaul. If the first network device is the fifth network device, that is, the first carrier and the first cell are co-located, or the first carrier and the first network device are co-located, then the terminal device can directly send uplink transmission to the first network device on the first carrier.

[0007] The handover mentioned in the embodiments of the present application may be a cell handover. The first cell may be a target cell, and the second cell may be a source cell. The first network device may be a target network device, and the second network device may be a source network device. In other words, the first network device is the network device corresponding to the first cell, and the second network device is the network device corresponding to the second cell.

[0008] It should be understood that a certain network device being a network device corresponding to a certain cell can be understood as a network device belonging to a certain cell, a network device serving a certain cell, or a cell of a certain network device. For example, cell information can be obtained from the network device, and this information can be scheduling information. This scheduling information can be used for uplink transmission from a terminal device to the network device, or for downlink transmission from the network device to the terminal device.

[0009] The first carrier is the carrier of the first cell, and the second carrier is the carrier of the second cell. It can be understood that the first carrier is the carrier corresponding to the first cell, and the second carrier is the carrier corresponding to the second cell; it can also be understood that the first carrier is the carrier configured by the first cell, and the second carrier is the carrier configured by the second cell.

[0010] The first carrier and the second carrier may belong to the same frequency band, and uplink transmissions sent by the terminal device on the first carrier and the second carrier are received by the same network device. In one possible embodiment, the first carrier and the second carrier are the same carrier.

[0011] The first carrier and the second carrier are the same carrier. It can be understood that the uplink transmissions sent by the terminal device on the first carrier and the second carrier are received by the same network device and meet at least one of the following conditions: the carrier frequencies of the first carrier and the second carrier are the same; the frequency reference points of the first carrier and the second carrier are the same; the frequency positions of the first carrier and the second carrier are the same; and the carrier bandwidths of the first carrier and the second carrier are the same.

[0012] After the terminal device switches from the second cell to the first cell, the carrier used for uplink transmission by the terminal device in the first cell is the first carrier. This means that after the terminal device switches, it communicates with the first network device in the first cell. The first network device can send downlink transmissions to the terminal device, and the terminal device can send uplink transmissions to the fourth network device on the first carrier. The fourth network device then sends the uplink transmission data to the first network device. For example, the fourth network device can send the uplink transmission data to the first network device via the backhaul. If the first network device is the fourth network device, then the terminal device can directly send uplink transmissions to the first network device on the first carrier. The first carrier and the second carrier belong to the same frequency band, and the uplink transmissions sent by the terminal device on the first carrier and the second carrier are received by the same network device. The second carrier is the carrier of the terminal device in the second cell.

[0013] After the terminal device switches from the second cell to the first cell, the carrier for uplink transmission by the terminal device in the first cell is the first carrier. It can also be understood that before and after the switching of the terminal device, the second cell and the first cell can send uplink transmission to the fourth network device on the first carrier in the same frequency band as the second carrier; it can also be understood that before and after the switching of the terminal device, the second cell and the first cell can send uplink transmission to the fourth network device on the first carrier in the same frequency position as the second carrier; it can also be understood that before and after the switching of the terminal device, the second cell and the first cell can continue to send uplink transmission to the fourth network device on the same carrier, that is, the second carrier. For example, the supplementary uplink (SUL) carrier of the terminal device in the first cell and the SUL carrier in the second cell belong to the same frequency band. The terminal device sends uplink transmission to the fourth network device on the SUL carrier in the two cells respectively. The fourth network device refers to a network device that can receive the uplink transmission sent by the terminal device on the SUL carrier. For another example, the SUL carrier of the terminal device in the first cell and the NUL carrier of the terminal device in the second cell belong to the same frequency band, and the terminal device sends an uplink transmission to the fourth network device on the NUL (or SUL) carrier in the two cells respectively, and the fourth network device refers to a network device that can receive the uplink transmission sent by the terminal device on the NUL (or SUL) carrier. For another example, the NUL carrier of the terminal device in the first cell and the SUL carrier of the terminal device in the second cell belong to the same frequency band, and the terminal device sends an uplink transmission to the fourth network device on the SUL (or NUL) carrier in the two cells respectively, and the fourth network device refers to a network device that can receive the uplink transmission sent by the terminal device on the SUL (or NUL) carrier. Therefore, the solution provided by the present application can effectively avoid the delay and interruption problems that may occur during the switching process of the terminal device to the first cell that requires random access, and can improve the efficiency of communication.

[0014] In one possible implementation, the communication method further includes: determining a first TA value based on the transmission timing (transmission timing) of the terminal device on the second carrier, the downlink timing (downlink timing) of the first cell and the timing advance (TA) offset value of the first cell, wherein the first TA value is the TA value of the terminal device on the first carrier.

[0015] It should be understood that if after the terminal device switches to the first cell, the uplink carrier is only the first carrier, then determining the TA value of the terminal device in the first carrier can also be understood as determining the TA value of the terminal device in the first cell; if after the terminal device switches to the first cell, the uplink carrier has the first carrier and other carriers, and when the TA values ​​of the first carrier and other carriers are the same, determining the TA value of the terminal device in the first carrier can also be understood as determining the TA value of the terminal device in the first cell.

[0016] After the terminal device determines that the carrier for uplink transmission of the terminal device in the first cell is the first carrier after the terminal device switches from the second cell to the first cell, the first TA value can be determined based on the transmission timing of the second carrier, the downlink timing of the first cell and the TA offset value of the first cell. The first carrier and the second carrier can be uplink carriers, so the transmission timing of the terminal device on the second carrier can be understood as the uplink timing of the terminal device on the second carrier. The first TA value is the TA value of the terminal device on the first carrier. In this way, the TA value on the first carrier can be determined without random access, thereby achieving uplink synchronization of the terminal device on the first carrier of the first cell. Therefore, the solution provided by the present application can effectively avoid the delay and interruption problems that may occur during the switching process of the terminal device to the first cell that requires random access, and can improve the efficiency of communication.

[0017] In a possible implementation manner, there is a carrier that is the same as the second carrier in valid carriers of the first cell.

[0018] The presence of a carrier identical to the second carrier in the valid carriers of the first cell can be understood as the presence of the second carrier in the valid carriers of the first cell. This can also be understood as one of the valid carriers of the first cell being the same as the second carrier. At least one carrier identical to the second carrier is present in the valid carriers of the first cell.

[0019] One of the effective carriers of the first cell and the second carrier are the same carrier. It can be understood that the uplink transmissions sent by the terminal device on the one of the effective carriers of the first cell and the second carrier are received by the same network device and meet at least one of the following conditions: the carrier frequencies of the first carrier and the second carrier are the same; the frequency reference points of the one of the effective carriers of the first cell and the second carrier are the same; the frequency positions of the one of the effective carriers of the first cell and the second carrier are the same; the carrier bandwidths of the one of the effective carriers of the first cell and the second carrier are the same.

[0020] An effective carrier can be understood as a carrier that covers a cell, or a carrier that covers a cell and can be configured, or a carrier that can be configured in a cell, or a carrier that belongs to a cell, or a carrier that is configured for use by a terminal device, or a carrier that is configured by a cell, or a carrier that is shared (configured) by at least one cell, or a carrier from which a terminal device can obtain configuration information from a system message of the cell, or a carrier from which a terminal device can obtain configuration information from a dedicated signaling of a cell. The effective carrier can be one or more, and this application does not limit this. The data or control information scheduled by the terminal device in the cell can be sent on an effective carrier.

[0021] In the solution provided in this application, if the first cell's valid carriers contain a carrier identical to the second carrier, it can be ensured that after a terminal device switches from the second cell to the first cell, the carrier used for uplink transmission by the terminal device in the first cell is the first carrier. This eliminates the need for random access, enabling handover and improving communication efficiency. If the first cell's valid carriers contain a carrier identical to the second carrier, random access will be required during the handover process, potentially leading to delays and interruptions.

[0022] In one possible implementation, the communication method further includes: when the carrier of the terminal device in the second cell is a third carrier and there is no carrier identical to the third carrier among the valid carriers of the first cell, the terminal device switches to the second carrier in the second cell.

[0023] In the solution provided in this application, if the carrier of the terminal device in the second cell is the third carrier, and there is no carrier identical to the third carrier among the valid carriers of the first cell, the terminal device can first switch from the third carrier to the second carrier in the second cell. This ensures that there is a carrier identical to the second carrier among the valid carriers of the first cell, and ensures that the terminal device can perform uplink transmission on the first carrier of the first cell after switching. In this way, switching can be achieved without random access, which can improve communication efficiency.

[0024] In one possible implementation, the communication method also includes: receiving first indication information sent by a second network device, the first indication information being used to indicate that the carrier for uplink transmission by the terminal device in the first cell is the first carrier, and the second network device is the network device corresponding to the second cell.

[0025] In the solution provided in this application, the second network device can send first indication information to the terminal device, instructing the terminal device to use the first carrier as the carrier for uplink transmission in the first cell. The determination that the carrier for uplink transmission in the first cell is the first carrier can be sent by the second network device to the terminal device, without the terminal device having to determine the carrier. Therefore, resource consumption of the terminal device can be reduced.

[0026] In a possible implementation, the communication method may further include: receiving first information sent by the second network device, where the first information includes a TA offset value of the first cell.

[0027] In the solution provided in the present application, the first information can be used by the terminal device to calculate the TA value of the first carrier, thereby achieving uplink synchronization of the terminal device on the first carrier of the first cell.

[0028] In one possible implementation, the first information also includes: at least one of: a time slot offset value between the first cell and the second cell, a system frame number offset value between the first cell and the second cell, and a frame boundary offset value between the first cell and the second cell; determining the first TA value based on the transmission timing of the terminal device on the second carrier, the downlink timing of the first cell and the TA offset value of the first cell includes: determining the first TA value based on the transmission timing of the terminal device on the second carrier, the downlink timing of the first cell and the first information.

[0029] In the solution provided in the present application, after the terminal device switches from the second cell to the first cell, the carrier for uplink transmission of the terminal device in the first cell is the first carrier, that is, before and after the switching, the terminal device sends uplink transmissions in the second cell and the first cell using the same frequency band of carriers, and the uplink transmissions sent by the terminal device on the first carrier and the second carrier are received by the same network device, so the sending timing of the uplink transmission sent by the terminal device should remain unchanged. When switching from the second cell to the first cell, when performing uplink transmission in the first cell, the terminal device needs to refer to the downlink timing of the first cell, and no longer needs to refer to the downlink timing of the second cell, so the TA value of the terminal device on the first carrier needs to be adjusted accordingly. Specifically, the first information can be sent to the terminal device by the second network device, the sending timing on the second carrier is determined by the terminal device, and the downlink timing of the first cell can be obtained by the terminal device by detecting the synchronization signal block (synchronization signal / PBCH block, SSB) information or other reference signals of the first cell. Therefore, the terminal device can determine the first TA value based on the first information, the sending timing on the second carrier and the downlink timing of the first cell, thereby realizing uplink synchronization of the terminal device on the first carrier of the first cell.

[0030] In a possible implementation, the first TA value may satisfy the following formula:

[0031] or

[0032] or

[0033] or

[0034] or

[0035]

[0036] Among them, N TA is the first TA value, T tt is the transmission timing of the terminal device on the second carrier, T is the downlink timing of the first cell, N TA-offset is the TA offset value of the first cell, T C =1 / (Δf max ·N f ), Δf max =480·10 3 Hz and N f =4096, T slot-offset is the time slot offset between the first cell and the second cell, T sfn-offsetis the system frame number offset between the first cell and the second cell, the T Fb-offset is the frame boundary offset value between the first cell and the second cell.

[0037] In the solution provided in the present application, the first TA value can be determined according to any one of the above formulas, thereby achieving uplink synchronization of the terminal device in the first carrier of the first cell.

[0038] In a possible implementation, the communication method may further include: receiving second indication information sent by the second network device, where the second indication information is used to indicate the first cell, and the second indication information includes an identity document (ID) of the first cell.

[0039] In the solution provided in the present application, the terminal device receives the second indication information sent by the second network device, and the terminal device can determine which first cell to switch to based on the ID of the first cell included in the second indication information.

[0040] In a possible implementation, the communication method may further include: receiving a measurement configuration sent by the second network device; reporting a measurement result of the fifth cell to the second network device according to the measurement configuration; and the third cell is at least one of the fifth cells.

[0041] In the solution provided in this application, the second network device obtains measurement results of a fifth cell from the terminal device by issuing a measurement configuration to the terminal device. The fifth cell may include the second cell and cells adjacent to the second cell. The second network device may determine whether the terminal device requires handover based on the measurement results of the fifth cell. If handover is required, the second network device may determine the first cell based on the measurement results of the third cell and information about the third cell, and then issue second indication information to the terminal device.

[0042] In one possible implementation, the communication method may further include: determining N fourth cells based on the measurement result of the third cell and the information of the third cell, where N is an integer greater than or equal to 1, and the effective carrier of the third cell and the effective carrier of the second cell have at least one identical carrier; sending indication information of the N fourth cells to the second network device; receiving second indication information sent by the second network device, the second indication information being used to indicate the first cell, the second indication information including the ID of the first cell, and the first cell being one of the N fourth cells.

[0043] In the solution provided in the present application, a terminal device can determine N fourth cells based on the measurement results of the third cell and the information of the third cell. The fourth cells can be candidate cells. The indication information of the N fourth cells is then reported to a second network device, which determines a first cell from the N fourth cells. The second network device then sends second indication information to the terminal device. Because the effective carriers of the third cell and the effective carriers of the second cell share at least one carrier, determining the N fourth cells based on the measurement results of the third cell and the information of the third cell can ensure that the effective carrier of each of the N fourth cells shares the same carrier as the effective carrier of the second cell. Furthermore, the first cell determined by the second network device from the N fourth cells can ensure that after the terminal device switches from the second cell to the first cell, the carrier used for uplink transmission by the terminal device in the first cell is the first carrier. This eliminates the need for random access during the handover process for the terminal device, achieving uplink synchronization of the terminal device on the first carrier of the first cell, thereby improving communication efficiency.

[0044] In one possible implementation, determining N fourth cells based on the measurement result of the third cell and the information of the third cell includes: determining the priority corresponding to each cell in the third cell based on the information of the third cell; and determining the N fourth cells based on the priority corresponding to each cell in the third cell and the measurement result of the third cell.

[0045] In the solution provided in this application, the third cell information may include the ID of each cell in the third cell and the valid carrier information of each cell. Different valid carrier information may correspond to different priorities, that is, different valid carrier information of each cell corresponds to different priorities. The terminal device then determines N fourth cells based on the corresponding priority of each cell in the third cell and the measurement result. The correspondence between the valid carrier information and the priority may be predefined by the protocol or determined by the second network device.

[0046] In a possible implementation manner, the communication method may further include: receiving a measurement configuration sent by the second network device; and determining a measurement result of the fifth cell according to the measurement configuration.

[0047] In the solution provided in the present application, the second network device can send a measurement configuration to the terminal device. After the terminal device obtains the measurement result of the fifth cell according to the measurement configuration, it does not need to report the measurement result of the fifth cell to the second network device for the terminal device to determine N fourth cells.

[0048] In a possible implementation manner, the communication method may further include: receiving information of the third cell sent by the second network device, where the third cell is at least one of the fifth cells.

[0049] In the solution provided in this application, a terminal device can receive information about a third cell sent by a second network device. The third cell is at least one of the fifth cells, so the terminal device can obtain the measurement result of the third cell from the measurement result of the fifth cell, and then determine N fourth cells based on the measurement result of the third cell and the information about the third cell.

[0050] In a possible implementation, the communication method may further include: sending second information on the first carrier, where the second information is used to confirm the handover to the first network device, where the first network device is a network device corresponding to the first cell.

[0051] In the solution provided in this application, a terminal device sends an uplink transmission to a fifth network device over a first carrier, and the fifth network device then sends the uplink transmission data to the first network device. If the first network device is the fifth network device, the terminal device can directly send the uplink transmission to the first network device over the first carrier. The uplink transmission can be second information, and the second information can be used to confirm the handover to the first network device. Confirming the handover can be confirming the handover of the terminal device from the second cell to the first cell. In this way, the terminal device can determine the first TA value without random access, and can also achieve uplink synchronization of the terminal device on the first carrier of the first cell based on the first TA value, which can improve communication efficiency.

[0052] In a possible implementation, the communication method may further include: receiving third indication information sent by the second network device, the third indication information being used to indicate whether the second TA value is the same as the first TA value, the second TA value being the TA value of the terminal device in the fourth carrier, and the fourth carrier being the carrier of the terminal device in the first cell that is different from the first carrier.

[0053] In the solution provided in the present application, the terminal device can determine the second TA value based on the third indication information from the second network device, and the fourth carrier can be an uplink carrier of the terminal device in the first cell that is different from the first carrier. For example, the fourth carrier can be a normal uplink (NUL) carrier. If the third indication information indicates that the second TA value is the same as the first TA value, the second TA value can be determined without random access, achieving uplink synchronization of the terminal device on the fourth carrier in the first cell, which can improve communication efficiency.

[0054] In a possible implementation manner, the communication method may further include: sending second information on the fourth carrier, where the second information is used to confirm the switching to the first network device.

[0055] In the solution provided in this application, a terminal device can send an uplink transmission to a sixth network device on a fourth carrier. The sixth network device refers to a network device that can receive the uplink transmission sent by the terminal device on the fourth carrier. The sixth network device then sends the uplink transmission data to the first network device. If the first network device is the sixth network device, the terminal device can directly send the uplink transmission to the first network device on the fourth carrier. The uplink transmission can be second information, and the second information can be used to confirm the handover to the first network device. In this way, the terminal device can determine the second TA value without random access, and can also achieve uplink synchronization of the terminal device on the fourth carrier of the first cell based on the second TA value, which can improve communication efficiency.

[0056] In the second aspect, the present application provides a communication method, which can be applied to a second network device or to a module (for example, a chip) in the second network device. The following description is given by taking the application to the second network device as an example. The method includes: sending first indication information to a terminal device, wherein the first indication information is used to indicate that the carrier for uplink transmission by the terminal device in the first cell is a first carrier, wherein the first carrier and the second carrier belong to the same frequency band, and the uplink transmissions sent by the terminal device on the first carrier and the second carrier are received by the same network device. The second carrier is the carrier of the terminal device in the second cell.

[0057] In the solution provided in the present application, the second network device may send first indication information to the terminal device to instruct the terminal device that the carrier for uplink transmission in the first cell is the first carrier.

[0058] The carrier for uplink transmission in the first cell is the first carrier. This means that after the terminal device switches, it communicates with the first network device in the first cell. The first network device can send downlink transmissions to the terminal device, and the terminal device can send uplink transmissions to the fourth network device on the first carrier. The fourth network device then sends the uplink transmission data to the first network device. For example, the fourth network device can send the uplink transmission data to the first network device via a backhaul. If the first network device is the fourth network device, then the terminal device can directly send uplink transmissions to the first network device on the first carrier. The first carrier and the second carrier belong to the same frequency band, and the uplink transmissions sent by the terminal device on the first carrier and the second carrier are received by the same network device. The second carrier is the carrier of the terminal device in the second cell.

[0059] The carrier for uplink transmission in the first cell is the first carrier, which can also be understood as, before the terminal device switches until after the switching, the terminal device can send uplink transmission to the fourth network device on the first carrier of the same frequency band as the second carrier in the second cell and the first cell; it can also be understood as, before the terminal device switches until after the switching, the terminal device can send uplink transmission to the fourth network device on the first carrier of the same frequency band as the second carrier in the second cell and the first cell; it can also be understood as, before the terminal device switches until after the switching, the terminal device can continue to send uplink transmission to the fourth network device on the same carrier, i.e., the second carrier, in the second cell and the first cell. For example, the terminal device's supplementary uplink (SUL) carrier in the first cell and the SUL carrier in the second cell belong to the same frequency band, and the terminal device sends uplink transmission to the fourth network device on the SUL carrier in the two cells respectively. The fourth network device refers to a network device that can receive the uplink transmission sent by the terminal device on the SUL carrier. For another example, the SUL carrier of the terminal device in the first cell and the NUL carrier of the terminal device in the second cell belong to the same frequency band, and the terminal device sends an uplink transmission to the fourth network device on the NUL (or SUL) carrier in the two cells respectively, and the fourth network device refers to a network device that can receive the uplink transmission sent by the terminal device on the NUL (or SUL) carrier. For another example, the NUL carrier of the terminal device in the first cell and the SUL carrier of the terminal device in the second cell belong to the same frequency band, and the terminal device sends an uplink transmission to the fourth network device on the SUL (or NUL) carrier in the two cells respectively, and the fourth network device refers to a network device that can receive the uplink transmission sent by the terminal device on the SUL (or NUL) carrier. Therefore, the solution provided by the present application can effectively avoid the delay and interruption problems that may occur during the switching process of the terminal device to the first cell that requires random access, and can improve the efficiency of communication.

[0060] After the terminal device determines that the carrier for uplink transmission of the terminal device in the first cell is the first carrier after the terminal device switches from the second cell to the first cell, the first TA value can be determined based on the transmission timing of the second carrier, the downlink timing of the first cell and the TA offset value of the first cell. The first TA value is the TA value of the terminal device on the first carrier. In this way, the TA value on the first carrier can be determined without random access, thereby achieving uplink synchronization of the terminal device on the first carrier in the first cell. Therefore, the solution provided by the present application can effectively avoid the delay and interruption problems that may occur during the switching process of the terminal device to the first cell that requires random access, and can improve the efficiency of communication.

[0061] It should be understood that the executor of the second aspect is the second network device, and the specific content of the second aspect corresponds to the content of the first aspect. The corresponding features and beneficial effects achieved by the second aspect can refer to the description of the first aspect. To avoid repetition, the detailed description is appropriately omitted here.

[0062] In a possible implementation, the communication method may further include: sending first information to the terminal device, where the first information includes a TA offset value of the first cell.

[0063] In a possible implementation, the first information also includes: at least one of a time slot offset value between the first cell and the second cell, a system frame number offset value between the first cell and the second cell, and a frame boundary offset value between the first cell and the second cell.

[0064] In one possible implementation, the communication method may further include: determining the first cell based on the measurement results of the third cell and the information of the third cell, the effective carrier of the third cell and the effective carrier of the second cell having at least one identical carrier; sending second indication information to the terminal device, the second indication information being used to indicate the first cell, and the second indication information including the ID of the first cell.

[0065] In the solution provided in the present application, the information of the third cell is known to the second terminal device. Since the third cell is at least one cell in the fifth cell, the measurement result of the third cell can be obtained from the measurement result of the fifth cell reported by the terminal device. The second network device can determine the first cell based on the measurement result of the third cell and the information of the third cell, and then send the second indication information to the terminal device. Since the effective carrier of the third cell and the effective carrier of the second cell have at least one identical carrier, the first cell is determined based on the measurement result of the third cell and the information of the third cell. This can ensure that after the terminal device switches from the second cell to the first cell, the carrier for uplink transmission of the terminal device in the first cell is the first carrier, so that the terminal device does not need random access during the switching process, and the uplink synchronization of the terminal device on the first carrier of the first cell is achieved, which can improve the efficiency of communication.

[0066] The effective carrier of the third cell is the same as the effective carrier of the second cell. This can be understood as one of the effective carriers of the second cell existing in the effective carrier of the third cell. This can also be understood as one of the effective carriers of the second cell being the same as one of the effective carriers of the third cell. The effective carrier of the third cell can have at least one of the same carriers as the effective carrier of the second cell.

[0067] One of the carriers in the effective carriers of the second cell and one of the carriers in the effective carriers of the third cell are the same carrier. It can be understood that the uplink transmissions sent by the terminal device on one of the carriers in the effective carriers of the second cell and one of the carriers in the effective carriers of the third cell are received by the same network device and meet at least one of the following conditions: the carrier frequency of one of the carriers in the effective carriers of the second cell and one of the carriers in the effective carriers of the third cell are the same; the frequency reference points of one of the carriers in the effective carriers of the second cell and one of the carriers in the effective carriers of the third cell are the same; the frequency positions of one of the carriers in the effective carriers of the second cell and one of the carriers in the effective carriers of the third cell are the same; the carrier bandwidths of the first carrier and the second carrier are the same.

[0068] In one possible implementation, determining the first cell based on the measurement result of the third cell and the information of the third cell includes: determining the priority corresponding to each cell in the third cell based on the information of the third cell; and determining the first cell based on the priority corresponding to each cell in the third cell and the measurement result of the third cell.

[0069] In the solution provided in this application, the third cell information may include the ID of each cell in the third cell and the valid carrier information of each cell. Different valid carrier information may correspond to different priorities, that is, different valid carrier information of each cell corresponds to different priorities. The second network device may determine the first cell based on the corresponding priority of each cell in the third cell and the measurement result. The correspondence between the valid carrier information and the priority may be predefined by the protocol or determined by the second network device.

[0070] In a possible implementation manner, the communication method may further include: sending a measurement configuration to the terminal device.

[0071] In a possible implementation, the communication method may further include: receiving a measurement result of a fifth cell sent by the terminal device; the third cell is at least one cell among the fifth cells.

[0072] In one possible implementation, the communication method may further include: receiving indication information of N fourth cells sent by the terminal device, where N is an integer greater than or equal to 1, and the N fourth cells are determined by the terminal device based on the measurement results of the third cell and the information of the third cell, and the effective carrier of the third cell and the effective carrier of the second cell have at least one identical carrier; determining the first cell based on the N fourth cells, and the first cell is one of the N fourth cells; sending second indication information to the terminal device, the second indication information is used to indicate the first cell, and the second indication information includes the ID of the first cell.

[0073] In the solution provided in this application, after the terminal device determines N fourth cells based on the measurement results of the third cell and information about the third cell, it reports indication information of the N fourth cells to the second network device. The effective carriers of the third cell and the effective carriers of the second cell have at least one common carrier. The second network device can determine a first cell from the N fourth cells and then send second indication information to the terminal device. The terminal device can determine the first cell to be switched to based on the ID of the first cell included in the second indication information.

[0074] In a possible implementation manner, the communication method may further include: sending a measurement configuration to the terminal device.

[0075] In a possible implementation, the communication method may further include: sending information of the third cell to the terminal device, where the third cell is at least one of the fifth cells.

[0076] In one possible implementation, the communication method may further include: sending third indication information to the terminal device, the third indication information being used to indicate whether the second TA value is the same as the first TA value, the second TA value being the TA value of the terminal device in a fourth carrier, and the fourth carrier being a carrier of the terminal device in the first cell that is different from the first carrier.

[0077] In a possible implementation, the communication method may further include: sending request information to a first network device, where the request information is used to request the terminal device to access the first network device, and the first network device is a network device corresponding to the first cell.

[0078] In the solution provided in this application, after determining the first cell, the second network device can send a request message to the first network device, requesting the terminal device to access the first network device, where the first network device is the network device corresponding to the first cell. If the first network device allows access, the second network device then sends a second indication message to the terminal device.

[0079] In a third aspect, the present application provides a communication method, which can be applied to a first network device or a module (e.g., a chip) in the first network device. The method is described below using the first network device as an example. The method includes: receiving a request message sent by a second network device, the request message being used to request the terminal device to access the first network device, where the second network device is a network device corresponding to a second cell.

[0080] In the solution provided in this application, after the second network device determines the first cell, it can send a request message to the first network device, requesting the terminal device to access the first network device. If the first network device allows access, the second network device sends a second instruction message to the terminal device; if the first network device does not allow access, the second network device can re-determine the first cell.

[0081] In a fourth aspect, the present application provides a communication method, which can be applied to a terminal device or a module (e.g., a chip) in the terminal device. The method is described below using the application to the terminal device as an example. The method includes: receiving third information sent by a second network device, the third information including first indication information and an ID of a first cell, the first indication information being used to instruct the terminal device to continue sending uplink transmissions to a fourth network device.

[0082] In the solution provided in the present application, the terminal device can determine which first cell to switch to based on the ID of the first cell included in the third information. It can also determine to continue sending uplink transmissions to the fourth network device in the first cell based on the first indication information included in the third information, specifically:

[0083] Before the terminal device switches, it communicates with the second network device in the second cell. The second network device can send downlink transmissions to the terminal device, and the terminal device can send uplink transmissions to the fourth network device. The fourth network device refers to a network device that can receive uplink transmissions sent by the terminal device in the second cell. The fourth network device then sends the uplink transmission data to the second network device. For example, the fourth network device can send the uplink transmission data to the second network device via a backhaul. If the second network device is the fourth network device, that is, the fourth network device and the second network device are co-located, then the terminal device can send uplink transmissions directly to the second network device. After the terminal device switches, it communicates with the first network device in the first cell. The first network device can send downlink transmissions to the terminal device, and the terminal device can send uplink transmissions to the fifth network device. The fifth network device refers to a network device that can receive uplink transmissions sent by the terminal device in the first cell. The fifth network device then sends the uplink transmission data to the first network device. For example, the fifth network device can send the uplink transmission data to the first network device via a backhaul. If the first network device is the fifth network device, that is, the fifth network device and the first network device are co-located, then the terminal device can directly send uplink transmission to the first network device.

[0084] Continuing to send uplink transmissions to the fourth network device can be understood as, before and after the terminal device switches, in the second cell and the first cell, it can send uplink transmissions to the same network device, that is, the fourth network device. Specifically: after the terminal device switches, it communicates with the first network device in the first cell, the first network device can send downlink transmissions to the terminal device, the terminal device can continue to send uplink transmissions to the fourth network device, and the fourth network device then sends the uplink transmission data to the first network device. For example, the fourth network device can send the uplink transmission data to the first network device via the backhaul. If the first network device is the fourth network device, then the terminal device can send uplink transmissions directly to the first network device. In this way, the terminal device can send uplink transmissions in the first cell without random access. Therefore, the solution provided by the present application can effectively avoid the delay and interruption problems that may occur during the switching process of the terminal device to the first cell that requires random access, and can improve the efficiency of communication.

[0085] In a possible implementation, the communication method may further include: determining a first TA value based on the first sending timing, the downlink timing of the first cell and the TA offset value of the first cell, wherein the first TA value is used to continue sending uplink transmission to the fourth network device.

[0086] In the solution provided in this application, the first transmission timing may be the transmission timing at which the terminal device transmits an uplink transmission in the second cell. Therefore, the first transmission timing may also be referred to as the first uplink timing. Thus, by using the first transmission timing to determine the first TA value, the first TA value can be determined without random access, thereby achieving uplink synchronization of the terminal device in the first cell and improving communication efficiency.

[0087] In a possible implementation, the communication method may further include: receiving first information sent by the second network device, where the first information includes a TA offset value of the first cell.

[0088] It should be understood that the specific content of the fourth aspect corresponds to the content of the first aspect, and the corresponding features and beneficial effects achieved in the fourth aspect can refer to the description of the first aspect. To avoid repetition, the detailed description is appropriately omitted here.

[0089] In a possible implementation, the first information also includes: at least one of a time slot offset value between the first cell and the second cell, a system frame number offset value between the first cell and the second cell, and a frame boundary offset value between the first cell and the second cell.

[0090] In one possible implementation, determining the first TA value based on the first sending timing, the downlink timing of the first cell and the TA offset value of the first cell includes: determining the first TA value based on the first sending timing, the downlink timing of the first cell and the first information.

[0091] In a possible implementation, the first TA value may satisfy the following formula:

[0092] or

[0093] or

[0094] or

[0095] or

[0096]

[0097] Among them, N TA is the first TA value, T tt is the first transmission timing, T is the downlink timing of the first cell, N TA-offset is the TA offset value of the first cell, T C =1 / (Δf max ·N f ), Δf max =480·10 3 Hz and N f =4096, T slot-offset is the time slot offset between the first cell and the second cell, T sfn-offset is the system frame number offset between the first cell and the second cell, the T Fb-offset is the frame boundary offset value between the first cell and the second cell.

[0098] In a possible implementation, the communication method may further include: receiving second indication information sent by the second network device, where the second indication information is used to indicate the first cell, and the second indication information includes an ID of the first cell.

[0099] In a possible implementation, the communication method may further include: receiving a measurement configuration sent by the second network device; reporting a measurement result of the fifth cell to the second network device according to the measurement configuration; and the third cell is at least one of the fifth cells.

[0100] In one possible implementation, the communication method may further include: determining N fourth cells based on the measurement result of the third cell and the information of the third cell, where N is an integer greater than or equal to 1, and the effective carrier of the third cell and the effective carrier of the second cell have at least one identical carrier; sending indication information of the N fourth cells to the second network device; receiving second indication information sent by the second network device, where the second indication information is used to indicate the first cell, and the second indication information includes the ID of the first cell.

[0101] In one possible implementation, determining N fourth cells based on the measurement result of the third cell and the information of the third cell includes: determining the priority corresponding to each cell in the third cell based on the information of the third cell; and determining the N fourth cells based on the priority corresponding to each cell in the third cell and the measurement result of the third cell.

[0102] In a possible implementation manner, the communication method may further include: receiving a measurement configuration sent by the second network device; and determining a measurement result of the fifth cell according to the measurement configuration.

[0103] In a possible implementation manner, the communication method may further include: receiving information of the third cell sent by the second network device, where the third cell is at least one of the fifth cells.

[0104] In one possible implementation, the communication method may further include: when the fourth network device is the first network device, sending uplink transmission information to the first network device, the uplink transmission information includes second information, and the second information is used to confirm the switching to the first network device; or when the fourth network device is the second network device, sending uplink transmission information to the second network device, the uplink transmission information includes second information, and the second information is used to confirm the switching to the first network device.

[0105] In the solution provided by the present application, the terminal device can send uplink transmissions to the same network device, i.e., the fourth network device, in the second cell and the first cell before and after the switching. If the fourth network device is the second network device, the terminal device can directly send uplink transmissions to the second network device; if the fourth network device is the first network device, the terminal device can directly send uplink transmissions to the first network device. The uplink transmission may include second information, and the second information is used to confirm the switching to the first network device. Confirming the switching may refer to the terminal device switching from the second cell to the first cell. In this way, uplink synchronization of the terminal device in the first cell can be achieved without random access. Therefore, the solution provided by the present application can effectively avoid the delay and interruption problems that may occur during the switching process of the terminal device to the first cell that requires random access, and can improve the efficiency of communication.

[0106] In a fifth aspect, the present application provides a communication method, which can be applied to a second network device or to a module (e.g., a chip) in the second network device. The method is described below using the second network device as an example. The method includes: sending third information to a terminal device, the third information including first indication information and an ID of a first cell, the first indication information being used to instruct the terminal device to continue sending uplink transmissions to a fourth network device.

[0107] In the solution provided in this application, the terminal device can determine which first cell to switch to based on the ID of the first cell included in the third information. It can also determine to continue sending uplink transmissions to the fourth network device in the first cell based on the first indication information included in the third information. In this way, the terminal device can achieve uplink synchronization on the first carrier of the first cell without the need for random access. Therefore, the solution provided in this application can effectively avoid the delays and interruptions that may occur during a handover of the terminal device to the first cell that requires random access, thereby improving communication efficiency.

[0108] It should be understood that the executor of the fifth aspect is the second network device, and the specific content of the fifth aspect corresponds to the content of the fourth aspect. The corresponding features and beneficial effects achieved in the fifth aspect can refer to the description of the fourth aspect. To avoid repetition, the detailed description is appropriately omitted here.

[0109] In a possible implementation, the communication method may further include: sending first information to the terminal device, where the first information includes a TA offset value of the first cell.

[0110] In a possible implementation, the first information also includes: at least one of a time slot offset value between the first cell and the second cell, a system frame number offset value between the first cell and the second cell, and a frame boundary offset value between the first cell and the second cell.

[0111] In one possible implementation, the communication method may further include: determining the first cell based on the measurement results of the third cell and the information of the third cell, the effective carrier of the third cell and the effective carrier of the second cell having at least one identical carrier; sending second indication information to the terminal device, the second indication information being used to indicate the first cell, and the second indication information including the ID of the first cell.

[0112] In one possible implementation, determining the first cell based on the measurement result of the third cell and the information of the third cell includes: determining the priority corresponding to each cell in the third cell based on the information of the third cell; and determining the first cell based on the priority corresponding to each cell in the third cell and the measurement result of the third cell.

[0113] In a possible implementation manner, the communication method may further include: sending a measurement configuration to the terminal device.

[0114] In a possible implementation, the communication method may further include: receiving a measurement result of a fifth cell sent by the terminal device; the third cell is at least one cell among the fifth cells.

[0115] In one possible implementation, the communication method may further include: receiving indication information of N fourth cells sent by the terminal device, where N is an integer greater than or equal to 1, and the N fourth cells are determined by the terminal device based on the measurement results of the third cell and the information of the third cell, and the effective carrier of the third cell and the effective carrier of the second cell have at least one identical carrier; determining the first cell based on the N fourth cells, and the first cell is one of the N fourth cells; sending second indication information to the terminal device, the second indication information is used to indicate the first cell, and the second indication information includes the ID of the first cell.

[0116] In a possible implementation manner, the communication method may further include: sending a measurement configuration to the terminal device.

[0117] In a possible implementation, the communication method may further include: sending information of the third cell to the terminal device, where the third cell is at least one of the fifth cells.

[0118] In a possible implementation, the communication method may further include: sending request information to the first network device, where the request information is used to request the terminal device to access the first network device.

[0119] In the solution provided in this application, after determining the first cell, the second network device can send a request message to the first network device, requesting the terminal device to access the first network device, where the first network device is the network device corresponding to the first cell. If the first network device allows access, the second network device then sends a second indication message to the terminal device.

[0120] In a possible implementation, the communication method may further include: when the fourth network device is the second network device, receiving uplink transmission information sent by the terminal device, the uplink transmission information includes second information, and the second information is used to confirm the switching to the first network device.

[0121] In the solution provided in this application, the terminal device can send uplink transmissions to the same network device, namely, the fourth network device, in both the second cell and the first cell, before and after the handover. If the fourth network device is the second network device, the terminal device can directly send uplink transmissions to the second network device. In this way, uplink synchronization of the terminal device in the first cell can be achieved without random access. Therefore, the solution provided in this application can effectively avoid the delays and interruptions that may occur during the handover process of the terminal device to the first cell that requires random access, thereby improving communication efficiency.

[0122] In a sixth aspect, the present application provides a communication method, which can be applied to a first network device or to a module (e.g., a chip) in the first network device. The method is described below using the first network device as an example. The method includes: when the fourth network device is the first network device, receiving uplink transmission information sent by a terminal device, the uplink transmission information including second information, and the second information is used to confirm the handover to the first network device.

[0123] In the solution provided by the present application, the terminal device can send uplink transmissions to the same network device, i.e., the fourth network device, in the second cell and the first cell before and after the switching. If the fourth network device is the first network device, then the terminal device can directly send uplink transmissions to the first network device. In this way, uplink synchronization of the terminal device in the first cell can be achieved without random access. Therefore, the solution provided by the present application can effectively avoid the delay and interruption problems that may occur during the switching process of the terminal device to the first cell that requires random access, and can improve the efficiency of communication.

[0124] In a possible implementation, the communication method may further include: receiving request information sent by the second network device, where the request information is used to request the terminal device to access the first network device.

[0125] In the solution provided in this application, after determining the first cell, the second network device can send a request message to the first network device, requesting the terminal device to access the first network device. If the first network device allows access, the second network device sends a second indication message to the terminal device.

[0126] In the seventh aspect, a communication method is provided, which can be applied to a terminal device or to a module (e.g., a chip) in the terminal device. The following description is given by taking the application to the terminal device as an example. The method includes: determining N fourth cells based on the information of the third cell and the measurement result of the fifth cell, where N is an integer greater than or equal to 1, and the effective carrier of the third cell and the effective carrier of the second cell have at least one identical carrier; sending indication information of the N fourth cells to a second network device, where the second network device is the network device corresponding to the second cell; and receiving second indication information sent by the second network device, where the second indication information is used to indicate the first cell, and the second indication information includes the ID of the first cell, and the first cell is one of the N fourth cells.

[0127] In the solution provided in this application, a terminal device can obtain measurement results for the fifth cell based on the measurement configuration, and then determine N fourth cells based on the measurement results of the fifth cell and information about the third cell from a second network terminal device. These N fourth cells are sent to a second network device, which then determines a first cell from the N fourth cells. Compared to determining the N fourth cells based solely on the measurement results and information about the third cell, although each of the third cells may be preferentially selected as the first cell if the effective carrier of the cell shares the same carrier as the effective carrier of the second cell, if the measurement results of each cell are poor, the first cell determined from the third cell does not meet the conditions for terminal device handover. Therefore, it is possible to re-determine the N fourth cells based on the measurement results of the sixth cell and report them to the second network device. The sixth cell can be a cell other than the third cell in the fifth cell. The sixth cell may include a cell whose effective carrier does not overlap with the effective carrier of the second cell but overlaps with the effective carriers of other cells other than the second cell. It may also include a cell whose effective carrier does not overlap with the effective carriers of both the second cell and other cells other than the second cell. Even if the effective carrier of the sixth cell does not exist and is the same as the effective carrier of the second cell, the measurement results of the N fourth cells determined by the sixth cell are good and meet the conditions of the first cell. Even if random access is required, the normal switching of the terminal device is guaranteed.

[0128] In one possible implementation, the determining of N fourth cells based on the information of the third cell and the measurement result of the fifth cell includes: when the third cell exists in the fifth cell, determining the priority corresponding to each cell in the third cell based on the information of the third cell; and determining the N fourth cells based on the priority corresponding to each cell in the third cell and the measurement result of the third cell.

[0129] In the solution provided in the present application, the terminal device can determine the measurement results of the fifth cell based on the measurement configuration sent by the second network device, and can also receive the information of the third cell sent by the second network device. It first determines whether the third cell exists in the fifth cell. If the third cell exists in the fifth cell, N fourth cells can be determined based on the information of the third cell and the measurement results of the third cell. Specifically: the information of the third cell may include the ID of each cell in the third cell and the effective carrier information of each cell. Different effective carrier information may correspond to different priorities, that is, different effective carrier information of each cell corresponds to different priorities. The terminal device then determines N fourth cells based on the priority corresponding to each cell in the third cell and the measurement results. The correspondence between the effective carrier information and the priority can be predefined by the protocol or determined by the second network device.

[0130] If the measurement results of the N fourth cells determined based on the information of the third cell and the measurement result of the third cell are not good, the N fourth cells may be re-determined based on the measurement result of the sixth cell.

[0131] In a possible implementation, determining the N fourth cells according to the information of the third cell and the measurement result of the fifth cell includes: when there is no third cell in the fifth cell, determining the N fourth cells according to the measurement result of the fifth cell.

[0132] In the solution provided in this application, the terminal device first determines whether there is a third cell in the fifth cell. If there is no third cell in the fifth cell, N fourth cells can be determined based on the measurement results of the fifth cell to ensure normal switching of the terminal device.

[0133] In a possible implementation, the communication method may further include: receiving a measurement configuration sent by a second network device, where the second network device is a network device corresponding to the second cell; and determining a measurement result of the fifth cell according to the measurement configuration.

[0134] In the solution provided in the present application, the second network device can send a measurement configuration to the terminal device. After the terminal device obtains the measurement result of the fifth cell according to the measurement configuration, it does not need to report the measurement result of the fifth cell to the second network device for the terminal device to determine N fourth cells.

[0135] In a possible implementation manner, the communication method may further include: receiving the information of the third cell sent by the second network device.

[0136] In the solution provided in this application, the terminal device can receive information about the third cell sent by the second network device.

[0137] In a possible implementation, the communication method may further include: receiving a measurement configuration sent by a second network device, where the second network device is a network device corresponding to the second cell; and reporting the measurement result of the fifth cell to the second network device according to the measurement configuration.

[0138] In the solution provided in this application, the second network device obtains the measurement result of the fifth cell from the terminal device by sending a measurement configuration to the terminal device. After the second network device obtains the measurement result of the fifth cell, it can determine the first cell.

[0139] In an eighth aspect, the present application provides a communication method, which can be applied to a second network device or to a module (e.g., a chip) in the second network device. The method is described below using the second network device as an example. The method includes: determining a first cell based on information about a third cell and a measurement result of a fifth cell, wherein the effective carrier of the third cell and the effective carrier of the second cell have at least one identical carrier.

[0140] In the solution provided in this application, the second network device can issue a measurement configuration to the terminal device, receive the measurement results of the fifth cell determined according to the measurement configuration reported by the terminal device, and then determine the first cell based on the measurement results of the fifth cell and the information of the third cell. Compared with determining the first cell based solely on the measurement results and information of the third cell, although each cell in the third cell may be preferentially selected as the first cell if the effective carrier of the cell is the same as the effective carrier of the second cell, if the measurement results of each cell are poor, the first cell determined from the third cell does not meet the conditions for terminal device handover. Therefore, it is possible to consider re-determining the first cell based on the measurement results of the sixth cell. The sixth cell can be a cell other than the third cell in the fifth cell. The sixth cell can include a cell whose effective carrier does not overlap with the effective carrier of the second cell, but overlaps with the effective carriers of other cells other than the second cell. It can also include a cell whose effective carrier does not overlap with the effective carriers of the second cell and other cells other than the second cell. Even if the effective carrier of the sixth cell does not overlap with the effective carrier of the second cell, if the measurement results of the first cell determined based on the sixth cell are good, normal handover of the terminal device is guaranteed even if random access is required.

[0141] It should be understood that the executor of the eighth aspect is the second network device, and the specific content of the eighth aspect corresponds to the content of the seventh aspect. The corresponding features of the eighth aspect and the beneficial effects achieved can refer to the description of the seventh aspect. In order to avoid repetition, the detailed description is appropriately omitted here.

[0142] In a possible implementation, determining the first cell based on the information of the third cell and the measurement result of the fifth cell includes: when the third cell exists in the fifth cell, determining the priority corresponding to each cell in the third cell based on the information of the third cell; and determining the first cell based on the priority corresponding to each cell in the third cell and the measurement result of the third cell.

[0143] In the solution provided in the present application, the second network device can receive the measurement results of the fifth cell sent by the terminal device, first determine whether there is a third cell in the fifth cell, and if there is a third cell in the fifth cell, then determine the first cell based on the information of the third cell and the measurement results of the third cell. Specifically: the information of the third cell may include the ID of each cell in the third cell and the effective carrier information of each cell. Different effective carrier information may correspond to different priorities, that is, different effective carrier information of each cell corresponds to different priorities. The second network device then determines the first cell based on the priority corresponding to each cell in the third cell and the measurement results. The correspondence between the effective carrier information and the priority may be predefined by the protocol or determined by the second network device.

[0144] If the measurement result of the first cell determined based on the information of the third cell and the measurement result of the third cell are both not good, the first cell may be re-determined based on the measurement result of the sixth cell.

[0145] In a possible implementation, determining the first cell according to the information of the third cell and the measurement result of the fifth cell includes: determining the first cell according to the measurement result of the fifth cell when the third cell does not exist in the fifth cell.

[0146] In the solution provided in this application, the second network device first determines whether there is a third cell in the fifth cell. If there is no third cell in the fifth cell, the first cell can be determined based on the measurement result of the fifth cell to ensure normal switching of the terminal device.

[0147] In a possible implementation manner, the communication method may further include: sending a measurement configuration to the terminal device; and receiving a measurement result of the fifth cell sent by the terminal device.

[0148] In one possible implementation, the communication method may further include: receiving indication information of N fourth cells sent by a terminal device, where N is an integer greater than or equal to 1, and the N fourth cells are determined by the terminal device based on the information of the third cell and the measurement result of the fifth cell, and the effective carrier of the third cell and the effective carrier of the second cell have at least one identical carrier; determining a first cell based on the N fourth cells, and the first cell is one of the N fourth cells.

[0149] In a possible implementation manner, the communication method may further include: sending a measurement configuration to the terminal device.

[0150] In a possible implementation, the communication method may further include: sending the information of the third cell to the terminal device.

[0151] In a ninth aspect, a communication device is provided, which may be a terminal device or a module (e.g., a chip) in the terminal device. The communication device may include:

[0152] A processing unit, used to determine that after the terminal device switches from the second cell to the first cell, the carrier for uplink transmission of the terminal device in the first cell is the first carrier; wherein the first carrier and the second carrier belong to the same frequency band, and the second carrier is the carrier of the terminal device in the second cell.

[0153] In one possible implementation, the processing unit is also used to determine a first TA value based on the transmission timing of the terminal device on the second carrier, the downlink timing of the first cell and the TA offset value of the first cell, where the first TA value is the TA value of the terminal device on the first carrier.

[0154] In a possible implementation manner, there is a carrier that is the same as the second carrier in valid carriers of the first cell.

[0155] In a possible implementation, when the carrier of the terminal device in the second cell is the third carrier and there is no carrier identical to the third carrier among the valid carriers of the first cell, the terminal device switches to the second carrier in the second cell.

[0156] In a possible implementation, the communication device may further include:

[0157] The transceiver unit is used to receive first indication information sent by the second network device, where the first indication information is used to indicate that the carrier used by the terminal device for uplink transmission in the first cell is the first carrier, and the second network device is the network device corresponding to the second cell.

[0158] In a possible implementation, the transceiver unit is further configured to receive first information sent by the second network device, where the first information includes a TA offset value of the first cell.

[0159] In a possible implementation, the first information further includes: at least one of a timeslot offset value between the first cell and the second cell, a system frame number offset value between the first cell and the second cell, and a frame boundary offset value between the first cell and the second cell;

[0160] The processing unit determines the first TA value according to the transmission timing of the terminal device on the second carrier, the downlink timing of the first cell and the TA offset value of the first cell, including: determining the first TA value according to the transmission timing of the terminal device on the second carrier, the downlink timing of the first cell and the first information.

[0161] In a possible implementation, the first TA value may satisfy the following formula:

[0162] or

[0163] or

[0164] or

[0165] or

[0166]

[0167] Among them, N TA is the first TA value, T tt is the transmission timing of the terminal device on the second carrier, T is the downlink timing of the first cell, N TA-offset is the TA offset value of the first cell, T C =1 / (Δf max ·N f ), Δf max =480·10 3 Hz and N f =4096, T slot-offset is the time slot offset between the first cell and the second cell, T sfn-offset is the system frame number offset between the first cell and the second cell, the T Fb-offset is the frame boundary offset value between the first cell and the second cell.

[0168] In a possible implementation, the transceiver unit is further configured to receive second indication information sent by the second network device, where the second indication information is used to indicate the first cell, and the second indication information includes an ID of the first cell.

[0169] In a possible implementation, the transceiver unit is further configured to receive a measurement configuration sent by the second network device; report a measurement result of the fifth cell to the second network device according to the measurement configuration; and the third cell is at least one of the fifth cells.

[0170] In a possible implementation, the processing unit is further configured to determine N fourth cells based on the measurement result of the third cell and the information of the third cell, where N is an integer greater than or equal to 1, and the valid carrier of the third cell and the valid carrier of the second cell have at least one identical carrier;

[0171] The transceiver unit is further used to send indication information of the N fourth cells to the second network device; receive second indication information sent by the second network device, where the second indication information is used to indicate the first cell, and the second indication information includes the ID of the first cell, and the first cell is one of the N fourth cells.

[0172] In one possible implementation, the processing unit determines N fourth cells based on the measurement result of the third cell and the information of the third cell, including: determining the priority corresponding to each cell in the third cell based on the information of the third cell; and determining the N fourth cells based on the priority corresponding to each cell in the third cell and the measurement result of the third cell.

[0173] In a possible implementation manner, the transceiver unit is further configured to receive a measurement configuration sent by the second network device;

[0174] The processing unit is further configured to determine a measurement result of the fifth cell according to the measurement configuration.

[0175] In a possible implementation, the transceiver unit is further configured to receive information about the third cell sent by the second network device, where the third cell is at least one of the fifth cells.

[0176] In a possible implementation, the transceiver unit is further configured to send second information on the first carrier, where the second information is used to confirm the handover to the first network device, where the first network device is a network device corresponding to the first cell.

[0177] In one possible implementation, the transceiver unit is further used to receive third indication information sent by the second network device, where the third indication information is used to indicate whether the second TA value is the same as the first TA value, and the second TA value is the TA value of the terminal device in the fourth carrier, and the fourth carrier is a carrier of the terminal device in the first cell that is different from the first carrier.

[0178] In a possible implementation, the transceiver unit is further configured to send second information on the fourth carrier, where the second information is used to confirm the switching to the first network device.

[0179] In a tenth aspect, a communication device is provided, which may be a second network device or a module (e.g., a chip) in the second network device. The communication device may include:

[0180] A transceiver unit is used to send first indication information to a terminal device, where the first indication information is used to indicate that the carrier used by the terminal device for uplink transmission in the first cell is a first carrier, wherein the first carrier and the second carrier belong to the same frequency band, and the second carrier is a carrier of the second cell.

[0181] In a possible implementation, the transceiver unit is further used to send first information to the terminal device, where the first information includes a TA offset value of the first cell.

[0182] In a possible implementation, the first information also includes: at least one of a time slot offset value between the first cell and the second cell, a system frame number offset value between the first cell and the second cell, and a frame boundary offset value between the first cell and the second cell.

[0183] In a possible implementation, the communication device may further include:

[0184] a processing unit, configured to determine, based on a measurement result of a third cell and information about the third cell, the first cell, where an effective carrier of the third cell and an effective carrier of the second cell have at least one identical carrier;

[0185] The transceiver unit is further used to send second indication information to the terminal device, where the second indication information is used to indicate the first cell, and the second indication information includes the ID of the first cell.

[0186] In one possible implementation, the processing unit determines the first cell based on the measurement result of the third cell and the information of the third cell, including: determining the priority corresponding to each cell in the third cell based on the information of the third cell; and determining the first cell based on the priority corresponding to each cell in the third cell and the measurement result of the third cell.

[0187] In a possible implementation, the transceiver unit is further configured to send a measurement configuration to the terminal device;

[0188] In a possible implementation, the transceiver unit is further configured to receive a measurement result of a fifth cell sent by the terminal device; and the third cell is at least one of the fifth cells.

[0189] In a possible implementation, the transceiver unit is further configured to receive indication information of N fourth cells sent by the terminal device, where N is an integer greater than or equal to 1, the N fourth cells are determined by the terminal device based on the measurement result of the third cell and the information of the third cell, and the effective carrier of the third cell and the effective carrier of the second cell have at least one identical carrier;

[0190] The processing unit is further configured to determine the first cell according to the N fourth cells, where the first cell is one of the N fourth cells;

[0191] The transceiver unit is further used to send second indication information to the terminal device, where the second indication information is used to indicate the first cell, and the second indication information includes the ID of the first cell.

[0192] In a possible implementation manner, the transceiver unit is further configured to send a measurement configuration to the terminal device.

[0193] In a possible implementation, the transceiver unit is further configured to send information of the third cell to the terminal device, where the third cell is at least one of the fifth cells.

[0194] In one possible implementation, the transceiver unit is further used to send third indication information to the terminal device, where the third indication information is used to indicate whether the second TA value is the same as the first TA value, and the second TA value is the TA value of the terminal device in the fourth carrier, and the fourth carrier is a carrier of the terminal device in the first cell that is different from the first carrier.

[0195] In a possible implementation, the transceiver unit is further used to send request information to a first network device, where the request information is used to request the terminal device to access the first network device, and the first network device is a network device corresponding to the first cell.

[0196] In an eleventh aspect, a communication device is provided, which may be a first network device or a module (e.g., a chip) in the first network device. The communication device may include:

[0197] The transceiver unit is used to receive request information sent by the second network device, where the request information is used to request the terminal device to access the first network device, and the second network device is the network device corresponding to the second cell.

[0198] In a twelfth aspect, a communication device is provided, which may be a terminal device or a module (e.g., a chip) in the terminal device. The communication device may include: a transceiver unit configured to receive third information sent by a second network device, the third information including first indication information and an ID of a first cell, the first indication information being configured to instruct the terminal device to continue sending uplink transmissions to a fourth network device.

[0199] In one possible implementation, the communication device may also include: a processing unit, configured to determine a first TA value based on the first sending timing, the downlink timing of the first cell, and the TA offset value of the first cell, wherein the first TA value is used to continue sending uplink transmission to the fourth network device.

[0200] In a possible implementation, the transceiver unit is further configured to receive first information sent by the second network device, where the first information includes a TA offset value of the first cell.

[0201] In a possible implementation, the first information also includes: at least one of a time slot offset value between the first cell and the second cell, a system frame number offset value between the first cell and the second cell, and a frame boundary offset value between the first cell and the second cell.

[0202] In one possible implementation, the processing unit determines the first TA value based on the first transmission timing, the downlink timing of the first cell and the TA offset value of the first cell, including: determining the first TA value based on the first transmission timing, the downlink timing of the first cell and the first information.

[0203] In a possible implementation, the first TA value may satisfy the following formula:

[0204] or

[0205] or

[0206] or

[0207] or

[0208]

[0209] Among them, N TA is the first TA value, T tt is the first transmission timing, T is the downlink timing of the first cell, N TA-offset is the TA offset value of the first cell, T C =1 / (Δf max ·N f ), Δf max =480·10 3 Hz and N f =4096, T slot-offset is the time slot offset between the first cell and the second cell, T sfn-offset is the system frame number offset between the first cell and the second cell, the T Fb-offset is the frame boundary offset value between the first cell and the second cell.

[0210] In a possible implementation, the transceiver unit is further configured to receive second indication information sent by the second network device, where the second indication information is used to indicate the first cell, and the second indication information includes an ID of the first cell.

[0211] In a possible implementation, the transceiver unit is further configured to receive a measurement configuration sent by the second network device; report a measurement result of the fifth cell to the second network device according to the measurement configuration; and the third cell is at least one of the fifth cells.

[0212] In a possible implementation, the processing unit is further configured to determine N fourth cells based on the measurement result of the third cell and the information of the third cell, where N is an integer greater than or equal to 1, and the valid carrier of the third cell and the valid carrier of the second cell have at least one identical carrier;

[0213] The transceiver unit is also used to send indication information of the N fourth cells to the second network device; receive second indication information sent by the second network device, where the second indication information is used to indicate the first cell, and the second indication information includes the ID of the first cell, and the first cell is one of the N fourth cells.

[0214] In one possible implementation, the processing unit determines N fourth cells based on the measurement result of the third cell and the information of the third cell, including: determining the priority corresponding to each cell in the third cell based on the information of the third cell; and determining the N fourth cells based on the priority corresponding to each cell in the third cell and the measurement result of the third cell.

[0215] In a possible implementation manner, the transceiver unit is further configured to receive a measurement configuration sent by the second network device; and determine a measurement result of the fifth cell according to the measurement configuration.

[0216] In a possible implementation, the transceiver unit is further configured to receive information about the third cell sent by the second network device, where the third cell is at least one of the fifth cells.

[0217] In one possible implementation, the transceiver unit is further configured to, when the fourth network device is the first network device, send uplink transmission information to the first network device, the uplink transmission information including second information, and the second information being used to confirm the switching to the first network device; or, when the fourth network device is the second network device, send uplink transmission information to the second network device, the uplink transmission information including second information, and the second information being used to confirm the switching to the first network device.

[0218] In a thirteenth aspect, a communication device is provided, which may be a second network device or a module (e.g., a chip) in the second network device. The communication device may include: a transceiver unit configured to send third information to a terminal device, the third information including first indication information and an ID of a first cell, the first indication information being configured to instruct the terminal device to continue sending uplink transmissions to a fourth network device.

[0219] In a possible implementation, the transceiver unit is further used to send first information to the terminal device, where the first information includes a TA offset value of the first cell.

[0220] In a possible implementation, the first information also includes: at least one of a time slot offset value between the first cell and the second cell, a system frame number offset value between the first cell and the second cell, and a frame boundary offset value between the first cell and the second cell.

[0221] In a possible implementation, the communication device may further include: a processing unit, configured to determine the first cell based on a measurement result of a third cell and information about the third cell, wherein an effective carrier of the third cell and an effective carrier of the second cell have at least one identical carrier;

[0222] The transceiver unit is further used to send second indication information to the terminal device, where the second indication information is used to indicate the first cell, and the second indication information includes the ID of the first cell.

[0223] In one possible implementation, the processing unit determines the first cell based on the measurement result of the third cell and the information of the third cell, including: determining the priority corresponding to each cell in the third cell based on the information of the third cell; and determining the first cell based on the priority corresponding to each cell in the third cell and the measurement result of the third cell.

[0224] In a possible implementation manner, the transceiver unit is further configured to send a measurement configuration to the terminal device.

[0225] In a possible implementation, the transceiver unit is further configured to receive a measurement result of a fifth cell sent by the terminal device; and the third cell is at least one of the fifth cells.

[0226] In a possible implementation, the transceiver unit is further configured to receive indication information of N fourth cells sent by the terminal device, where N is an integer greater than or equal to 1, the N fourth cells are determined by the terminal device based on the measurement result of the third cell and the information of the third cell, and the effective carrier of the third cell and the effective carrier of the second cell have at least one identical carrier;

[0227] The processing unit is further configured to determine the first cell according to the N fourth cells, where the first cell is one of the N fourth cells;

[0228] The transceiver unit is further used to send second indication information to the terminal device, where the second indication information is used to indicate the first cell, and the second indication information includes the ID of the first cell.

[0229] In a possible implementation manner, the transceiver unit is further configured to send a measurement configuration to the terminal device.

[0230] In a possible implementation, the transceiver unit is further configured to send information of the third cell to the terminal device, where the third cell is at least one of the fifth cells.

[0231] In a possible implementation, the transceiver unit is further configured to send a request message to the first network device, where the request message is used to request the terminal device to access the first network device.

[0232] In a possible implementation, the transceiver unit is further used to receive uplink transmission information sent by the terminal device when the fourth network device is the second network device, and the uplink transmission information includes second information, and the second information is used to confirm the switching to the first network device.

[0233] In a fourteenth aspect, a communication device is provided, which may be a first network device or a module (e.g., a chip) in the first network device. The communication device may include: a transceiver unit configured to, when the fourth network device is the first network device, receive uplink transmission information sent by a terminal device, the uplink transmission information including second information, the second information being used to confirm the handover to the first network device.

[0234] In a possible implementation, the transceiver unit is further configured to receive request information sent by the second network device, where the request information is used to request the terminal device to access the first network device.

[0235] In a fifteenth aspect, a communication device is provided, which may be a terminal device or a module (e.g., a chip) in the terminal device. The communication device may include: a processing unit configured to determine N fourth cells based on information about the third cell and a measurement result of the fifth cell, where N is an integer greater than or equal to 1, and the valid carriers of the third cell and the valid carriers of the second cell have at least one identical carrier;

[0236] a transceiver unit, configured to send indication information of the N fourth cells to a second network device, where the second network device is a network device corresponding to the second cell;

[0237] The transceiver unit is further used to receive second indication information sent by the second network device, where the second indication information is used to indicate the first cell, and the second indication information includes the ID of the first cell, where the first cell is one of the N fourth cells.

[0238] In a possible implementation, the processing unit determines N fourth cells based on the information of the third cell and the measurement result of the fifth cell, including: when the third cell exists in the fifth cell, determining the priority corresponding to each cell in the third cell based on the information of the third cell; and determining the N fourth cells based on the priority corresponding to each cell in the third cell and the measurement result of the third cell.

[0239] In a possible implementation, the processing unit determines N fourth cells according to the information of the third cell and the measurement result of the fifth cell, including: when there is no third cell in the fifth cell, determining the N fourth cells according to the measurement result of the fifth cell.

[0240] In a possible implementation, the transceiver unit is further configured to receive a measurement configuration sent by a second network device, where the second network device is a network device corresponding to the second cell;

[0241] The processing unit is further configured to determine a measurement result of the fifth cell according to the measurement configuration.

[0242] In a possible implementation manner, the transceiver unit is further configured to receive the information of the third cell sent by the second network device.

[0243] In a possible implementation, the transceiver unit is further configured to receive a measurement configuration sent by a second network device, where the second network device is a network device corresponding to the second cell; and report the measurement result of the fifth cell to the second network device according to the measurement configuration.

[0244] In a sixteenth aspect, a communication device is provided. The communication device may be a second network device or a module (e.g., a chip) in the second network device. The communication device may include:

[0245] The processing unit is configured to determine the first cell according to the information of the third cell and the measurement result of the fifth cell, wherein the valid carrier of the third cell and the valid carrier of the second cell have at least one identical carrier.

[0246] In a possible implementation, the processing unit determines the first cell based on the information of the third cell and the measurement result of the fifth cell, including: when the third cell exists in the fifth cell, determining the priority corresponding to each cell in the third cell based on the information of the third cell; and determining the first cell based on the priority corresponding to each cell in the third cell and the measurement result of the third cell.

[0247] In a possible implementation, the processing unit determining the first cell according to the information of the third cell and the measurement result of the fifth cell includes: determining the first cell according to the measurement result of the fifth cell when the third cell does not exist in the fifth cell.

[0248] In a possible implementation, the communication device further includes:

[0249] A transceiver unit is used to send a measurement configuration to the terminal device; and receive the measurement result of the fifth cell sent by the terminal device.

[0250] In a possible implementation, the transceiver unit is further configured to receive indication information of N fourth cells sent by the terminal device, where N is an integer greater than or equal to 1, the N fourth cells are determined by the terminal device based on the information of the third cell and the measurement result of the fifth cell, and the effective carrier of the third cell and the effective carrier of the second cell have at least one identical carrier;

[0251] The processing unit is further configured to determine a first cell according to the N fourth cells, where the first cell is one of the N fourth cells.

[0252] In a possible implementation manner, the transceiver unit is further configured to send a measurement configuration to the terminal device.

[0253] In a possible implementation, the transceiver unit is further configured to send the information of the third cell to the terminal device.

[0254] In a seventeenth aspect, a communication device is provided, which may be a terminal device or a module (e.g., a chip) in the terminal device. The communication device may include a processor for executing a computer program, and when the computer program is executed, the communication device performs

[0255] The communication method provided by the first aspect or any embodiment of the first aspect; or

[0256] The communication method provided by the fourth aspect or any embodiment of the fourth aspect; or

[0257] The communication method provided by the seventh aspect or any embodiment of the seventh aspect.

[0258] In a possible implementation manner, the communication device may further include a memory for storing the computer program.

[0259] In aspect 18, a communication device is provided, which may be a second network device or a module (e.g., a chip) in the second network device. The communication device may include a processor for executing a computer program, and when the computer program is executed, the communication device performs

[0260] The communication method provided by the second aspect or any embodiment of the second aspect; or

[0261] The communication method provided by the fifth aspect or any implementation manner of the fifth aspect; or

[0262] The communication method provided by the eighth aspect or any embodiment of the eighth aspect.

[0263] In a possible implementation manner, the communication device may further include a memory for storing the computer program.

[0264] In a nineteenth aspect, a communication device is provided, which may be a first network device or a module (e.g., a chip) in the first network device. The communication device may include a processor for executing a computer program, and when the computer program is executed, the communication device performs

[0265] The communication method provided by the third aspect or any embodiment of the third aspect; or

[0266] The communication method provided by the sixth aspect or any embodiment of the sixth aspect.

[0267] In a possible implementation manner, the communication device may further include a memory for storing the computer program.

[0268] In the twentieth aspect, a communication system is provided, which includes the communication device of the ninth aspect, the communication device of the tenth aspect, the communication device of the eleventh aspect, the communication device of the twelfth aspect, the communication device of the thirteenth aspect, the communication device of the fourteenth aspect, the communication device of the fifteenth aspect and the communication device of the sixteenth aspect.

[0269] In the twenty-first aspect, a computer-readable storage medium is provided, on which a computer program or computer instructions are stored. When the computer program or computer instructions are executed, some or all of the steps of the communication method described in the above-mentioned first aspect and any possible implementation thereof, the second aspect and any possible implementation thereof, the third aspect and any possible implementation thereof, the fourth aspect and any possible implementation thereof, the fifth aspect and any possible implementation thereof, the sixth aspect and any possible implementation thereof, the seventh aspect and any possible implementation thereof, and the eighth aspect and any possible implementation thereof are executed.

[0270] In the twenty-second aspect, a computer program product comprising executable instructions is also provided. When the computer program product is run on a user device, some or all of the steps of the communication method described in the above-mentioned first aspect and any possible implementation thereof, the second aspect and any possible implementation thereof, the third aspect and any possible implementation thereof, the fourth aspect and any possible implementation thereof, the fifth aspect and any possible implementation thereof, the sixth aspect and any possible implementation thereof, the seventh aspect and any possible implementation thereof, and the eighth aspect and any possible implementation thereof are executed.

[0271] In a twenty-third aspect, a chip system is provided, comprising a processor and further comprising a memory, for implementing the communication methods described in the first aspect and any possible implementation thereof, the second aspect and any possible implementation thereof, the third aspect and any possible implementation thereof, the fourth aspect and any possible implementation thereof, the fifth aspect and any possible implementation thereof, the sixth aspect and any possible implementation thereof, the seventh aspect and any possible implementation thereof, and the eighth aspect and any possible implementation thereof. The chip system may be composed of a chip alone, or may include a chip and other discrete components. BRIEF DESCRIPTION OF THE DRAWINGS

[0272] Figure 1 This is a schematic diagram of uplink carrier coverage provided by an embodiment of the present application;

[0273] Figure 2 This is a schematic diagram of the relationship between the uplink and downlink timing of data provided in an embodiment of the present application;

[0274] Figure 3 This is a schematic diagram of a network architecture provided by an embodiment of the present application;

[0275] Figure 4 This is a flow chart of a communication method provided in an embodiment of the present application;

[0276] Figure 5 This is a schematic diagram of the relationship between uplink and downlink timing of another data provided in an embodiment of the present application;

[0277] Figure 6 This is a flow chart of another communication method provided in an embodiment of the present application;

[0278] Figure 7 This is a flow chart of another communication method provided in an embodiment of the present application;

[0279] Figure 8 This is a flow chart of another communication method provided in an embodiment of the present application;

[0280] Figure 9 This is a flow chart of another communication method provided in an embodiment of the present application;

[0281] Figure 10 This is a flow chart of another communication method provided in an embodiment of the present application;

[0282] Figure 11 This is a schematic diagram of a switching scenario provided by an embodiment of the present application;

[0283] Figure 12 This is a schematic diagram of another switching scenario provided by an embodiment of the present application;

[0284] Figure 13 This is another switching scenario diagram provided by an embodiment of the present application;

[0285] Figure 14 This is another switching scenario diagram provided by an embodiment of the present application;

[0286] Figure 15 This is another switching scenario diagram provided by an embodiment of the present application;

[0287] Figure 16 This is a schematic structural diagram of a communication device provided in an embodiment of the present application;

[0288] Figure 17 is a structural diagram of another communication device provided in an embodiment of the present application;

[0289] Figure 18 This is a structural diagram of another communication device provided in an embodiment of the present application;

[0290] Figure 19 This is a structural diagram of another communication device provided in an embodiment of the present application;

[0291] Figure 20 This is a structural diagram of another communication device provided in an embodiment of the present application;

[0292] Figure 21 This is a structural diagram of another communication device provided in an embodiment of the present application;

[0293] Figure 22 This is a structural diagram of another communication device provided in an embodiment of the present application;

[0294] Figure 23 This is a structural diagram of another communication device provided in an embodiment of the present application;

[0295] Figure 24 This is a structural diagram of another communication device provided in an embodiment of the present application;

[0296] Figure 25 This is a structural diagram of another communication device provided in an embodiment of the present application;

[0297] Figure 26 This is a structural diagram of another communication device provided in an embodiment of the present application;

[0298] Figure 27 This is a structural diagram of another communication device provided in an embodiment of the present application;

[0299] Figure 28 This is a structural diagram of another communication device provided in an embodiment of the present application;

[0300] Figure 29 This is a structural diagram of another communication device provided in an embodiment of the present application;

[0301] Figure 30 This is a structural diagram of another communication device provided in an embodiment of the present application;

[0302] Figure 31 This is a structural diagram of another communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0303] In order to facilitate understanding of this application, the relevant technical knowledge involved in the embodiments of this application is first introduced here.

[0304] 1. Assisted uplink

[0305] A cell generally includes an uplink carrier (the uplink carrier can be called a NUL carrier) and a downlink (DL) carrier. The uplink carrier and the DL carrier are in the same frequency band. However, in the 5G era, the frequency bands and frequencies used are relatively high, such as millimeter waves. The higher the frequency band, the greater the signal transmission loss. Since the transmission power of the terminal device is limited, this will lead to limited uplink coverage of the terminal device. Therefore, the 3rd Generation Partnership Project (3GPP) NR protocol introduced the SUL carrier in the uplink carrier. In addition to configuring a NUL carrier in a cell, NR supports configuring a SUL carrier. The terminal device can perform uplink transmission through the NUL carrier and / or SUL carrier of the cell. The system information block (SIB) of the serving cell may include whether the cell is configured with a SUL carrier.

[0306] The SUL carrier is generally in a low-frequency band, such as the long-term evolution (LTE) band, and can be used to ensure uplink coverage of terminal devices. If the SUL carrier frequency is lower than the NUL carrier frequency, the coverage of the SUL carrier will be greater than that of the NUL carrier due to factors such as propagation loss. In this way, the use of the SUL carrier can improve the uplink coverage of the cell. If the coverage of the NUL carrier is smaller than that of the DL carrier corresponding to the NUL due to factors such as frequency, device, and time slot ratio, the use of the SUL carrier can also align the coverage of the cell's uplink carrier with the coverage of the DL carrier corresponding to the NUL. When the difference between the SUL carrier frequency and the NUL carrier frequency is larger, the SUL coverage will be greater than the coverage of the DL carrier corresponding to the NUL.

[0307] See also Figure 1 , Figure 1 FIG. 1 is a schematic diagram of an uplink carrier coverage provided by an embodiment of the present application. Figure 1 As shown, the cell at site 1 has a NUL carrier and the DL carrier corresponding to the NUL carrier; the cell at site 2 has a NUL carrier, the DL carrier corresponding to the NUL carrier, and a SUL carrier. If the SUL carrier frequency at site 2 is lower than the NUL carrier frequency, the uplink coverage of the SUL carrier may be greater than the coverage of the DL carrier corresponding to the co-located NUL carrier. This allows multiple cells to be covered by the same SUL carrier. For example, the cell at site 1 can also be covered by the SUL carrier at site 2.

[0308] 2. TA

[0309] The existence of TA is to ensure that the time for uplink data sent by terminal devices at different distances in the same cell to reach the network device falls within the cyclic prefix. TA-offset The offset of the uplink transmission time relative to the downlink reception time is used to ensure that the terminal equipment in the time division duplex (TDD) mode has enough time to complete the switching from uplink transmission to downlink reception at the same frequency point. TA-offset The value can be configured by RRC. If there is no higher-layer signaling notification, the value predefined by the protocol can be used.

[0310] The NUL carrier and the SUL carrier can belong to the same timing advance group (TAG). The two uplink carriers in a TAG use the same timing reference cell and the same TA value. The TA offset value N of the NUL carrier and the SUL carrier is TA-offset The same is true.

[0311] See also Figure 2 , Figure 2 This is a schematic diagram of the structure of uplink data transmission provided by the embodiment of the present application. Figure 2 As shown, the terminal device sends the i-th uplink frame, which should be T before the starting position of the downlink frame corresponding to the terminal device. TA =(N TA +N TA-offset )T C Start. C =1 / (Δf max ·N f ), Δf max =480·10 3 Hz and N f =4096. In other words, T TA =(N TA +N TA-offset )T CIt can also be understood as the difference between the terminal device transmission timing and the downlink timing, where the downlink timing is defined as the time of the first detection path (in time) of receiving the corresponding downlink frame from the reference cell. For the service cell in the primary timing advance group (PTAG), the terminal device should use the special cell (SpCell) as the reference cell to obtain the terminal device transmission timing of the cell in the PTAG. For the service cell in the secondary timing advance group (STAG), the terminal device can use any activated SpCell as the reference cell to obtain the terminal device transmission timing of the cell in the STAG. The terminal device transmission timing can also be understood as Figure 2 The starting time of uplink frame transmission of the terminal device in.

[0312] In NR, when a terminal device switches, it needs to perform random access on the NUL carrier or SUL carrier of the first cell to obtain the TA value of the uplink carrier of the first cell, and then complete the uplink synchronization of the terminal device in the first cell based on the TA value. However, the handover process of the terminal device to the target cell that requires random access may cause delays and interruptions, thereby reducing communication efficiency.

[0313] In view of the above problems, an embodiment of the present application provides a communication method that can improve the efficiency of communication.

[0314] In an embodiment of the present application, when the signal quality of the current cell deteriorates, the terminal device can perform a handover. Compared to the prior art, in which the terminal device requires random access during the handover process to determine the TA value of the first carrier after the terminal device switches to the first cell, in an embodiment of the present application, after the terminal device switches from the second cell to the first cell, the carrier for uplink transmission of the terminal device in the first cell is the first carrier. The first carrier can be the carrier of the terminal device in the first cell, and the second carrier can be the carrier of the terminal device in the second cell. The TA value of the terminal device on the first carrier is then determined. For example, if the carrier of the terminal device in the second cell is a SUL carrier, then after switching to the first cell, the terminal device can continue to send uplink transmissions on the SUL carrier in the first cell. That is, before and after the handover, the terminal device can send uplink transmissions on the same carrier, namely, the SUL carrier, in the second cell and the first cell, and then determine the TA value of the SUL carrier of the terminal device in the first cell. In this way, uplink synchronization of the terminal device on the SUL carrier of the first cell can be achieved without random access. Therefore, the solution provided by the present application can effectively avoid the delay and interruption problems that may occur during the handover process of the terminal device to the first cell that requires random access, and can improve communication efficiency.

[0315] In order to better understand the communication method, device and computer-readable storage medium provided by the embodiments of the present application, the network architecture used in the embodiments of the present application is described below. Figure 3 , Figure 3 This is a network architecture diagram provided by an embodiment of the present application. Figure 3 As shown, the network architecture may include at least two cells, for example, a first cell belonging to a first network device and a second cell belonging to a second network device. The network architecture may also include at least one terminal device. When the terminal device moves from the second cell to the first cell, switching may occur, that is, switching from the second cell to the first cell.

[0316] The handover mentioned in the embodiments of the present application may be a cell handover. The first cell may be a target cell, and the second cell may be a source cell. The first network device may be a target network device, and the second network device may be a source network device. In other words, the first network device is the network device corresponding to the first cell, and the second network device is the network device corresponding to the second cell.

[0317] It should be understood that the first cell can be a neighboring cell of the second cell. In other words, in the present application, the first cell is one of at least one neighboring cell of the second cell, and the neighboring cell of the second cell can also be a candidate cell. The above-mentioned first cell can be one of the candidate cells, and the embodiments of the present application are not limited to this.

[0318] It should be understood that "first", "second", "third", "fourth", etc. in the embodiments of the present application are only for distinction, and the first, second, third, and fourth are not intended to limit the embodiments of the present application.

[0319] It should be understood that in the embodiments of the present application, a network device may correspond to one or more cells. The second cell and the first cell may belong to the same network device, that is, the first network device and the second network device may be the same network device. In this case, the terminal device performs handover within the network device. Alternatively, the second cell and the first cell may belong to different network devices, that is, the first network device and the second network device may be different network devices. In this case, the terminal device performs handover between network devices.

[0320] The technical solutions of the embodiments of the present application can be applied to various communication systems, such as: global system for mobile communication (GSM) system, code division multiple access (CDMA) system, wideband code division multiple access (WCDMA) system, general packet radio service (GPRS), LTE system, LTE frequency division duplex (FDD) system, LTE time division duplex (TDD) system, universal mobile telecommunications system (UMTS) system, enhanced data rate for GSM evolution (EDGE) system, world-wide interoperability for microwave access (WiMAX) system. The technical solutions of the embodiments of the present application can also be applied to other communication systems, such as public land mobile network (PLMN) system, fifth generation (5G) system or communication system after 5G or new radio (NR), etc., and the embodiments of the present application are not limited to this.

[0321] The terminal device in the embodiments of the present application may also be referred to as a user terminal. A user terminal may be a device that includes wireless transceiver functions and can cooperate with network equipment to provide communication services to users. Specifically, a user terminal may refer to a UE, user, satellite phone, satellite terminal, subscriber unit, cellular phone, smart phone, smart watch, wireless data card, personal digital assistant (PDA), computer, tablet computer, wireless modem, handheld device, laptop computer, machine type communication (MTC) terminal, etc. For example, the terminal device can be a vehicle-mounted device or a wearable device, a virtual reality (VR) terminal device, an augmented reality (AR) terminal device, a wireless terminal in industrial control, a wireless terminal in self-driving, a wireless terminal in remote medical, a wireless terminal in a smart grid, a wireless terminal in transportation safety, a wireless terminal in a smart city, a wireless terminal in a smart home, a terminal device in a 5G network or a future communication network, etc. The embodiments of the present application do not specifically limit this.

[0322] The network device in the embodiment of the present application can be a device for communicating with a terminal device, for example, it can be a base transceiver station (BTS) in a global system for mobile communications (GSM) system or code division multiple access (Code Division Multiple Access), or a base station (NodeB, NB) in a wideband code division multiple access (WCDMA) system, or an evolved base station (eNB or eNodeB) in an LTE system, or a wireless controller in a cloud radio access network (CRAN) scenario, or the network device can be a relay station, an access point, a vehicle-mounted device, a wearable device, and a network device in a future 5G network or a network after 5G, or a network device in a future evolved PLMN network, etc., for example, a transmission point (TRP or TP) in an NR system, a base station (gNB) in an NR system, one or a group of antenna panels (including multiple antenna panels) of a base station in a 5G system, etc., and the embodiment of the present application is not limited to this.

[0323] Optionally, the base station in the embodiment of the present application may include various forms of base stations, such as: macro base stations, micro base stations (also called small stations), relay stations, access points, next-generation base stations (gNodeB, gNB), transmission points (transmitting and receiving point, TRP), transmitting points (transmitting point, TP), mobile switching centers, and devices that perform base station functions in device-to-device (D2D), vehicle-to-everything (V2X), and machine-to-machine (M2M) communications, etc. The embodiment of the present application does not specifically limit this.

[0324] The embodiments of the present application do not particularly limit the specific structure of the execution subject of the method provided by the embodiments of the present application. As long as it is possible to communicate according to the method provided by the embodiments of the present application by running a program that records the code of the method provided by the embodiments of the present application, for example, the execution subject of the method provided by the embodiments of the present application can be a terminal device or a network device, or a functional module in the terminal device or the network device that can call and execute the program.

[0325] In addition, various aspects or features of the present application can be implemented as methods, devices or products using standard programming and / or engineering techniques. The term "product" as used in this application covers computer programs that can be accessed from any computer-readable device, carrier or medium. For example, computer-readable media can include, but are not limited to: magnetic storage devices (e.g., hard disks, floppy disks or tapes, etc.), optical disks (e.g., compact discs (CDs), digital versatile discs (DVDs), etc.), smart cards and flash memory devices (e.g., erasable programmable read-only memories (EPROMs), cards, sticks or key drives, etc.). In addition, the various storage media described in this application can represent one or more devices and / or other machine-readable media for storing information. The term "machine-readable medium" can include, but is not limited to, wireless channels and various other media capable of storing, containing and / or carrying instructions and / or data.

[0326] Based on the above network architecture, please refer to Figure 4 , Figure 4 This is a flow chart of a communication method provided by an embodiment of the present application. Among them, the functions performed by the terminal device in the present application can also be performed by a module (for example, a chip) in the terminal device, the functions performed by the first network device in the present application can also be performed by a module (for example, a chip) in the first network device, and the functions performed by the second network device in the present application can also be performed by a module (for example, a chip) in the second network device. Figure 4 As shown, the communication method may include the following steps.

[0327] 401. The second network device sends a measurement configuration to the terminal device.

[0328] Accordingly, the terminal device may receive the measurement configuration sent by the second network device.

[0329] The second network device can configure the measurement process and report of the terminal device according to the measurement configuration, and can send the measurement configuration message to the terminal device through an RRC message. The measurement configuration message may include the object to be measured by the terminal device, the cell list, the reporting method, the measurement identifier and event parameters, and may also include a measurement signal, etc. For example, the measurement signal can be an SSB signal or a reference signal. When the measurement conditions change, the second network device can send the new measurement conditions to the terminal device. The second network device may be the network device corresponding to the second cell.

[0330] It should be understood that a certain network device being a network device corresponding to a certain cell can be understood as a network device belonging to a certain cell, a network device serving a certain cell, or a cell of a certain network device. For example, cell information can be obtained from the network device, and this information can be scheduling information. This scheduling information can be used for uplink transmission from a terminal device to the network device, or for downlink transmission from the network device to the terminal device.

[0331] 402. The terminal device sends the measurement result of the fifth cell to the second network device.

[0332] Correspondingly, the second network device can receive the measurement result of the fifth cell sent by the terminal device.

[0333] After receiving the measurement configuration sent by the second network device, the terminal device may measure the second cell, and may also determine, based on the RRC message, whether it is necessary to perform measurement of a neighboring cell of the second cell, thereby obtaining a measurement result of the fifth cell. The fifth cell includes the cell corresponding to the measurement configuration, and may include the second cell, or a neighboring cell of the second cell. The measurement result of the fifth cell may include the measurement result of the second cell, and may also include the measurement result of the neighboring cell.

[0334] After the terminal device determines the measurement result of the fifth cell according to the measurement configuration, it can send the measurement result of the fifth cell to the second network device. The terminal device may send the measurement result of the fifth cell to the second network device periodically or event-triggered. For example, when the measurement report condition is met, the terminal device reports the measurement result of the fifth cell to the second network device. The measurement result may include reference signal received power (RSRP), reference signal received quality (RSRQ), and signal-to-noise and interference ratio (SINR).

[0335] 403. The second network device determines the first cell according to the information of the third cell and the measurement result of the third cell.

[0336] After the second network device receives the measurement result of the fifth cell sent by the terminal device, it can decide to hand over the terminal device based on the measurement result of the fifth cell, that is, whether the terminal device needs to be switched. If the terminal device needs to be switched, the first cell can be determined based on the information of the third cell and the measurement result of the third cell. The third cell can be at least one cell in the fifth cell, and the effective carrier of the third cell has at least one identical carrier with the effective carrier of the second cell.

[0337] The information of the third cell is known to the second terminal device. Since the third cell is at least one cell in the fifth cell, the measurement result of the third cell can be obtained from the measurement result of the fifth cell reported by the terminal device. Therefore, the second network device can determine the first cell based on the measurement result of the third cell and the information of the third cell.

[0338] The effective carrier of the third cell is the same as the effective carrier of the second cell. This can be understood as one of the effective carriers of the second cell existing in the effective carrier of the third cell. This can also be understood as one of the effective carriers of the second cell being the same as one of the effective carriers of the third cell. The effective carrier of the third cell can have at least one of the same carriers as the effective carrier of the second cell.

[0339] One of the carriers in the effective carriers of the second cell and one of the carriers in the effective carriers of the third cell are the same carrier. It can be understood that the uplink transmissions sent by the terminal device on one of the carriers in the effective carriers of the second cell and one of the carriers in the effective carriers of the third cell are received by the same network device and meet at least one of the following conditions: the carrier frequency of one of the carriers in the effective carriers of the second cell and one of the carriers in the effective carriers of the third cell are the same; the frequency reference points of one of the carriers in the effective carriers of the second cell and one of the carriers in the effective carriers of the third cell are the same; the frequency positions of one of the carriers in the effective carriers of the second cell and one of the carriers in the effective carriers of the third cell are the same; the carrier bandwidths of the first carrier and the second carrier are the same.

[0340] The information of the third cell may include the ID of each cell in the third cell and the valid carrier information of each cell. Specifically, in one embodiment, the information of the third cell may be as shown in Table 1.

[0341] Table 1

[0342] Carrier community Carrier 1 (frequency) Community 1, Community 2…Community 5 Carrier 2 (frequency) Community 1, Community 6…Community 10 … … Carrier n (frequency) Cell 11, ...Cell m, Cell n

[0343] As shown in Table 1, the information of the third cell may include the ID of each cell, for example, cell 1, cell 2, ..., cell m, cell n, where n and m are integers greater than or equal to 1. The information of the third cell may also include information on which cells each carrier is configured in, for example, carrier 1 is configured in cell 1, cell 2, ..., cell 5; carrier 2 is configured in cell 1, cell 6, ..., cell 10; ...; carrier n is configured in cell 11, ..., cell m, cell n; and may also include frequency information of each carrier, for example, the frequency of carrier 1, the frequency of carrier 2, ..., the frequency of carrier n. The cell IDs and numbers, and carrier IDs and numbers in Table 1 are for illustrative purposes only and are not intended to be limiting in this application.

[0344] Carriers and the cells they are located in can be co-located or at different locations. For example, carrier 1 and cells 1, 2, ..., and 5 can be co-located or at different locations; carrier 2 and cells 1, 6, ..., and 10 can be co-located or at different locations; and carrier n and cells 11, ..., m, and n can be co-located or at different locations.

[0345] Carrier 1, carrier 2, ..., carrier n include the second carrier, and also include other carriers in the valid carriers of the second cell except the second carrier.

[0346] In one embodiment, the information of the third cell may be as shown in Table 2.

[0347] Table 2

[0348]

[0349]

[0350] As shown in Table 2, the information of the third cell may include the ID of each cell, for example, cell 1, cell 2, ..., cell n, where n is an integer greater than or equal to 1; it may also include the carrier of each cell, for example, cell 1 has carrier 1, carrier 2, ..., carrier 5; cell 2 has carrier 1, carrier 6, ..., carrier 10; ...; cell n has carrier 11, ..., carrier m, carrier n, where m is an integer greater than or equal to 1; it may also include frequency information of each carrier, for example, the frequency of carrier 1, the frequency of carrier 2, ..., the frequency of carrier n. The cell IDs and numbers, and carrier IDs and numbers in Table 2 are for illustrative purposes only and are not intended to be limiting in this application.

[0351] The carriers of different cells can be co-located or not. For example, cell 1 and carriers 1, 2, ..., 5 can be co-located or not; cell 2 and carriers 1, 6, ..., 10 can be co-located or not; cell n and carriers 11, ..., m, n can be co-located or not.

[0352] Carrier 1, carrier 2, ..., carrier n include the second carrier, and also include other carriers in the valid carriers of the second cell except the second carrier.

[0353] An effective carrier can be understood as a carrier that covers a cell, or a carrier that covers a cell and can be configured, or a carrier that can be configured in a cell, or a carrier that belongs to a cell, or a carrier that is configured for use by a terminal device, or a carrier that is configured by a cell, or a carrier that is shared (configured) by at least one cell, or a carrier from which a terminal device can obtain configuration information from a system message of the cell, or a carrier from which a terminal device can obtain configuration information from a dedicated signaling of a cell. The effective carrier can be one or more, and this application does not limit this. The data or control information scheduled by the terminal device in the cell can be sent on an effective carrier.

[0354] The second network device determines the first cell according to the information of the third cell and the measurement result of the third cell, specifically:

[0355] The second network device may first determine the priority corresponding to each cell in the third cell according to the information of the third cell, and then determine the first cell according to the priority corresponding to each cell in the third cell and the measurement result of the third cell:

[0356] The priority may be reflected by a priority value corresponding to each cell, and the priority value may be determined based on at least one value.

[0357] In one embodiment, the priority value may have a first value, a second value, a third value, and a fourth value, where:

[0358] If there is a carrier that is co-located with the second carrier among the valid carriers of the cell, the first value may be assigned to the cell, and the second carrier may be a carrier of the second cell;

[0359] If there is a carrier with a different station location from the second carrier among the valid carriers of the cell, the second value may be assigned to the cell;

[0360] If there is a carrier in the valid carriers of the cell that is co-located with other carriers in the valid carriers of the second cell except the second carrier, a third value may be assigned to the cell;

[0361] If there is a carrier in the valid carriers of the cell that has a different site from other carriers in the valid carriers of the second cell except the second carrier, a fourth value may be assigned to the cell.

[0362] It should be understood that co-location can represent the co-location between carriers, the co-location between cells, the co-location between network devices, the co-location between cells and carriers, the co-location between carriers and network devices, and the co-location between cells and network devices. For example, if the network device corresponding to a certain uplink carrier and the network device corresponding to the downlink carrier of the cell are at the same site, it can be said that the uplink carrier and the cell are co-located. If the network device corresponding to a certain uplink carrier and the network device corresponding to the downlink carrier of the cell are at different sites, it can be said that the uplink carrier and the cell are at different sites. The network device corresponding to the uplink carrier can be understood as a network device that can receive the uplink transmission sent by the terminal device on this carrier. The network device corresponding to the downlink carrier can be understood as a terminal device that can receive the downlink transmission of the network device on this carrier.

[0363] For example, two uplink carriers being co-located may indicate that the cells or network devices receiving data on these two carriers are at the same site, or are the same cell or the same network device. For another example, two carriers being co-located may indicate that the cells or network devices communicating with terminal devices on these two carriers are at the same site, or are the same cell or the same network device.

[0364] It should be understood that different station addresses can represent different station addresses between carriers, different station addresses between cells, different station addresses between network devices, different station addresses between cells and carriers, different station addresses between carriers and network devices, and different station addresses between cells and network devices. For example, different station addresses of two uplink carriers can represent that the cells or network devices receiving data on these two carriers are at different stations. For another example, different station addresses of two carriers can represent that the cells or network devices communicating with terminal devices on these two carriers are at different stations.

[0365] The first, second, third, and fourth values ​​can be different values, with priority given to cells with valid carriers that are co-located with the second carrier. For example, the first value can be greater than the second value, the second value can be greater than the third value, and the third value can be greater than the fourth value; or the first value can be greater than the third value, the third value can be greater than the second value, and the second value can be greater than the fourth value. Correspondingly, the larger the priority value, the higher the priority of the cell.

[0366] In one embodiment, the cell with the highest value can be selected as the priority of the cell, and each cell can be assigned once. For example, if the cell satisfies both the first and third values, the first value can be assigned to the cell based on the first value being greater than the third value.

[0367] In one embodiment, the sum of at least one of the first value, the second value, the third value, and the fourth value may be used as the priority value of the cell; or the weighted sum of at least one of the first value, the second value, the third value, and the fourth value may be used as the priority value of the cell. For example, if a cell satisfies both the first value and the third value, the sum of the first value and the third value may be used as the priority value of the cell, or the weighted sum of the first value and the third value may be used as the priority value of the cell.

[0368] After the second network device determines the priority corresponding to each cell in the third cell according to the information of the third cell, the first cell may be determined according to the priority corresponding to each cell in the third cell and the measurement result of the third cell. Specifically:

[0369] The measurement result of the third cell is digitized, and the total value of each cell is determined according to the priority value and the measurement result value corresponding to each cell in the third cell. The second network device can determine the first cell according to the total value of each cell. For example, the first cell can be the cell with the highest total value.

[0370] In one embodiment, when the priorities of the cells are the same, the cell with the better measurement result can be preferentially selected as the first cell according to the measurement results of the cells; when the measurement results of the cells are the same, the cell with the higher priority can be preferentially selected as the first cell according to the priorities of the cells.

[0371] It should be understood that the first value, the second value, the third value and the fourth value can be set in advance by the second network device, or can be predefined in the protocol, or can be set in real time when the information of the third cell is obtained. This application does not limit this.

[0372] 404. The second network device sends a request message to the first network device for requesting the terminal device to access the first network device.

[0373] Correspondingly, the first network device may receive the request information sent by the second network device for requesting the terminal device to access the first network device.

[0374] After determining the first cell, the second network device may send a request message to the first network device through a transparent RRC container, wherein the request message may be used to request the terminal device to access the first network device. The first network device may be a network device corresponding to the first cell.

[0375] The RRC container may carry information required to prepare for switching on the target side, which may include the first cell ID, the cell-radio network temporary identifier (C-RNTI) of the terminal device in the second network device, the RRM configuration including the inactive time of the terminal device, the system information block 1 (SIB1) from the second network device, and the terminal device capabilities for different radio access technologies (RAT). This information may also include measurement information reported by the terminal device (including beam-related information, if available).

[0376] Accordingly, after receiving the request information sent by the second network device for requesting the terminal device to access the first network device, the first network device can determine whether to allow the terminal device to access.

[0377] When the terminal device is allowed to access, the first network device may send permission information to the second network device for allowing the terminal device to access the first network device, and may also send a transparent container to be sent to the terminal device as an RRC message to enable the terminal device to perform switching.

[0378] If the terminal device is not allowed to access, the second network device can redetermine the first cell according to step 403, and then send a request message to the third network device to request the terminal device to access the third network device. The third network device can be the network device corresponding to the first cell redetermined by the second network device.

[0379] Correspondingly, the third network device may receive the request information sent by the second network device for requesting the terminal device to access the third network device, and determine whether to allow the terminal device to access.

[0380] In the case where the terminal device is allowed to access, the third network device sends permission information for allowing the terminal device to access the third network device to the second network device.

[0381] 405. The second network device sends second indication information for indicating information of the first cell to the terminal device.

[0382] Correspondingly, the terminal device can receive second indication information sent by the second network device to indicate information of the first cell.

[0383] After the second network device receives the permission information sent by the network device corresponding to the first cell to allow the terminal device to access, it can send second indication information to the terminal device, and the second indication information is used to indicate the information of the first cell. It can also trigger the terminal device to switch by sending a message to the terminal device. The message may include the information required to access the first cell: the first cell ID and the first network device security algorithm identifier of the selected security algorithm, etc. The message can be carried in an RRC message or a physical downlink shared channel (PDCCH) message. The terminal device receives the second indication information sent by the second network device, and the terminal device can determine which first cell to switch to by using the ID of the first cell included in the second indication information, so that the terminal device can access the first cell without reading system information, thereby improving communication efficiency.

[0384] 406. Determine that after the terminal device switches from the second cell to the first cell, the carrier for uplink transmission by the terminal device in the first cell is the first carrier.

[0385] After the terminal device receives the second indication information sent by the second network device, it can be determined that after the terminal device switches from the second cell to the first cell, the carrier on which the terminal device performs uplink transmission in the first cell is the first carrier. Before the terminal device switches until after the switching, the second cell and the first cell can perform uplink transmission on the first carrier in the same frequency band as the second carrier; it can also be understood that before the terminal device switches until after the switching, the second cell and the first cell can perform uplink transmission on the first carrier in the same frequency position as the second carrier; it can also be understood that before the terminal device switches until after the switching, the second cell and the first cell can continue to perform uplink transmission on the same carrier, that is, the second carrier.

[0386] The first carrier is the carrier of the first cell, and the second carrier is the carrier of the second cell. It can be understood that the first carrier is the carrier corresponding to the first cell, and the second carrier is the carrier corresponding to the second cell; it can also be understood that the first carrier is the carrier configured by the first cell, and the second carrier is the carrier configured by the second cell.

[0387] The first carrier and the second carrier may belong to the same frequency band, and uplink transmissions sent by the terminal device on the first carrier and the second carrier are received by the same network device. In one possible embodiment, the first carrier and the second carrier are the same carrier.

[0388] The first carrier and the second carrier are the same carrier. It can be understood that the uplink transmissions sent by the terminal device on the first carrier and the second carrier are received by the same network device and meet at least one of the following conditions: the carrier frequencies of the first carrier and the second carrier are the same; the frequency reference points of the first carrier and the second carrier are the same; the frequency positions of the first carrier and the second carrier are the same; and the carrier bandwidths of the first carrier and the second carrier are the same.

[0389] After the terminal device switches from the second cell to the first cell, the carrier used for uplink transmission by the terminal device in the first cell is the first carrier. This means that after the terminal device switches, it communicates with the first network device in the first cell. The first network device can send downlink transmissions to the terminal device, and the terminal device can send uplink transmissions to the fourth network device on the first carrier. The fourth network device then sends the uplink transmission data to the first network device. For example, the fourth network device can send the uplink transmission data to the first network device via the backhaul. If the first network device is the fourth network device, then the terminal device can directly send uplink transmissions to the first network device on the first carrier. The first carrier and the second carrier belong to the same frequency band, and the uplink transmissions sent by the terminal device on the first carrier and the second carrier are received by the same network device. The second carrier is the carrier of the terminal device in the second cell.

[0390] After the terminal device switches from the second cell to the first cell, the carrier for uplink transmission by the terminal device in the first cell is the first carrier. It can also be understood that before and after the switching of the terminal device, the second cell and the first cell can send uplink transmission to the fourth network device on the first carrier in the same frequency band as the second carrier; it can also be understood that before and after the switching of the terminal device, the second cell and the first cell can send uplink transmission to the fourth network device on the first carrier in the same frequency position as the second carrier; it can also be understood that before and after the switching of the terminal device, the second cell and the first cell can continue to send uplink transmission to the fourth network device on the same carrier, that is, the second carrier. For example, the supplementary uplink (SUL) carrier of the terminal device in the first cell and the SUL carrier in the second cell belong to the same frequency band. The terminal device sends uplink transmission to the fourth network device on the SUL carrier in the two cells respectively. The fourth network device refers to a network device that can receive the uplink transmission sent by the terminal device on the SUL carrier. For another example, the SUL carrier of the terminal device in the first cell and the NUL carrier of the terminal device in the second cell belong to the same frequency band, and the terminal device sends an uplink transmission to the fourth network device on the NUL (or SUL) carrier in the two cells respectively, and the fourth network device refers to a network device that can receive the uplink transmission sent by the terminal device on the NUL (or SUL) carrier. For another example, the NUL carrier of the terminal device in the first cell and the SUL carrier of the terminal device in the second cell belong to the same frequency band, and the terminal device sends an uplink transmission to the fourth network device on the SUL (or NUL) carrier in the two cells respectively, and the fourth network device refers to a network device that can receive the uplink transmission sent by the terminal device on the SUL (or NUL) carrier. Therefore, the solution provided by the present application can effectively avoid the delay and interruption problems that may occur during the switching process of the terminal device to the first cell that requires random access, and can improve the efficiency of communication.

[0391] In a first feasible implementation, there is a carrier identical to the second carrier in the effective carriers of the first cell. If there is a carrier identical to the second carrier in the effective carriers of the first cell, it can be ensured that after the terminal device switches from the second cell to the first cell, it performs uplink transmission on the first carrier; in one embodiment, if there is a carrier in the same frequency band as the second carrier in the effective carriers of the first cell, and the uplink transmissions sent by the terminal device on the effective carrier of the first cell and the second carrier are received by the same network device, it can also be ensured that after the terminal device switches from the second cell to the first cell, it performs uplink transmission on the first carrier. In this way, switching can be achieved without random access, which can improve the efficiency of communication. If there is no carrier identical to the second carrier in the effective carriers of the first cell, random access must be performed during the switching process of the terminal device, which may cause delays and interruptions.

[0392] The presence of a carrier identical to the second carrier in the valid carriers of the first cell can be understood as the presence of the second carrier in the valid carriers of the first cell. This can also be understood as one of the valid carriers of the first cell being the same as the second carrier. At least one carrier identical to the second carrier is present in the valid carriers of the first cell.

[0393] One of the effective carriers of the first cell and the second carrier are the same carrier. It can be understood that the uplink transmissions sent by the terminal device on the one of the effective carriers of the first cell and the second carrier are received by the same network device and meet at least one of the following conditions: the carrier frequency of one of the effective carriers of the first cell is the same as that of the second carrier; the frequency reference point of one of the effective carriers of the first cell and the second carrier is the same; the frequency position of one of the effective carriers of the first cell and the second carrier is the same; the carrier bandwidth of the first carrier and the second carrier is the same.

[0394] In another feasible implementation, if the carrier of the terminal device in the second cell is the third carrier and there is no carrier identical to the third carrier among the valid carriers of the first cell, the terminal device can first switch to the second carrier in the second cell, where the second carrier is the same carrier as the valid carriers of the first cell. In this way, it can be ensured that there is a carrier identical to the second carrier among the valid carriers of the first cell, and it can be ensured that the terminal device performs uplink transmission on the first carrier after switching. In this way, switching can be achieved without random access, which can improve communication efficiency.

[0395] In one embodiment, when the carrier of the terminal device in the second cell is the third carrier, and there is no carrier in the same frequency band as the third carrier in the effective carrier of the first cell, and the uplink transmission sent by the terminal device on the effective carrier of the first cell and the third carrier is not received by a network device, the terminal device can first switch to the second carrier in the second cell, and the second carrier is a carrier in the same frequency band as the effective carrier of the first cell, and the uplink transmission sent by the terminal device on the second carrier and the effective carrier of the first cell is received by the same network device.

[0396] In another feasible implementation, the second network device may send first indication information to the terminal device, indicating that the carrier used by the terminal device for uplink transmission in the first cell is the first carrier. After receiving the first indication information sent by the second network device, the terminal device may determine, based on the first indication information, that the carrier used by the terminal device for uplink transmission in the first cell is the first carrier. The information determining that the carrier used by the terminal device for uplink transmission in the first cell is the first carrier may be sent by the second network device to the terminal device, and the terminal device does not need to determine the information. Therefore, resource consumption of the terminal device can be reduced.

[0397] In one embodiment, the second network device may send fourth indication information to the terminal device, and the fourth indication information may be used to indicate whether the terminal device skips random access during the handover process. When the fourth indication information indicates that the terminal device skips random access during the handover process, the terminal device may determine the first carrier based on the first indication information or the carrier information of the terminal device in the second cell. For example, if the terminal device has only one SUL carrier in the second cell, and the SUL carrier and at least one SUL carrier in the valid carriers of the first cell are carriers of the same frequency band, and the terminal device sends uplink transmissions on the SUL carrier and at least one SUL carrier in the valid carriers of the first cell and are received by the same network device, then after receiving the fourth indication information, the terminal device skips the random access process and determines that the first carrier is the SUL carrier. For another example, if the terminal device has only one SUL carrier in the second cell, the terminal device receives the first indication information, and the first indication information indicates that the SUL carrier and at least one SUL carrier in the valid carriers of the first cell are carriers of the same frequency band, and the terminal device sends uplink transmissions on the SUL carrier and at least one SUL carrier in the valid carriers of the first cell and are received by the same network device, then after receiving the fourth indication information, the terminal device skips the random access process and determines that the first carrier is the SUL carrier. In this way, switching can be achieved without random access, which can improve communication efficiency.

[0398] In one embodiment, the second network device may also send fifth indication information to the terminal device. The fifth indication information may include indication information instructing the terminal device to continue using the second carrier resources, for example, to continue using a certain bandwidth part (BWP) in the second carrier resources. The certain BWP may be an initial BWP or a first activated BWP. The fifth indication information may also include an indication to the terminal device to no longer use the resources of the second carrier and to use new uplink resources. The new uplink resources may be an uplink authorization. The uplink authorization may be obtained by the terminal device in the first carrier or in the fourth carrier. The uplink authorization may also be obtained by the terminal device in the PDCCH message of the first cell. Through the fifth indication information, the terminal device can directly use all or part of the resources of the second carrier for communication without having to re-acquire the configuration information of the first carrier from the first cell.

[0399] In a possible implementation, the carrier of the terminal device in the second cell or the first cell may be one or more.

[0400] For example, assuming that the terminal device has a carrier in the second cell, and after switching to the first cell, the first cell also has a carrier, then the carrier of the terminal device in the first cell and the carrier in the second cell can be carriers of the same frequency band, and the uplink transmissions sent by the terminal device on these two carriers are received by the same network device.

[0401] For another example, assuming that the terminal device has a carrier in the second cell and after switching to the first cell, the first cell has multiple carriers, then one of the multiple carriers of the terminal device in the first cell and the carrier in the second cell can be carriers of the same frequency band, and the uplink transmissions sent by the terminal device on these two carriers are received by the same network device.

[0402] For another example, assuming that the terminal device has multiple carriers in the second cell, and after switching to the first cell, the first cell has one carrier, then the carrier of the terminal device in the first cell and one of the multiple carriers in the second cell can be carriers of the same frequency band, and the uplink transmissions sent by the terminal device on these two carriers are received by the same network device.

[0403] For another example, assuming that the terminal device has multiple carriers in the second cell, and after switching to the first cell, the first cell has multiple carriers, then the multiple carriers of the terminal device in the first cell and part or all of the multiple carriers in the second cell are carriers of the same frequency band, and the uplink transmissions sent by the terminal device on these part or all of the carriers are received by the same network device. For example, one of the multiple carriers of the terminal device in the first cell and one of the multiple carriers in the second cell are carriers of the same frequency band, and the uplink transmissions sent by the terminal device on these two carriers are received by the same network device; for another example, two of the multiple carriers of the terminal device in the first cell and two of the multiple carriers in the second cell are the same carrier.

[0404] In one possible implementation, the first carrier or the second carrier may be a NUL carrier, a SUL carrier, or at least one of the following carriers: a TDD carrier, an uplink time unit of a TDD carrier, an FDD carrier, and an uplink time unit of an FDD carrier, where the time unit is a time slot or a subframe. This can expand the range of carriers that can be used as SUL carriers.

[0405] In one possible implementation, the carrier of the terminal device in the second cell is a SUL carrier. After switching to the first cell, the carrier of the terminal device in the first cell can be a SUL carrier, or a NUL carrier (the carrier can be a SUL carrier relative to the second cell, and can be a NUL carrier relative to the first cell), or other carriers.

[0406] In one possible implementation, the carrier of the terminal device in the second cell is a NUL carrier. After switching to the first cell, the carrier of the terminal device in the first cell can be a SUL carrier (the carrier can be a NUL carrier relative to the second cell, and can be a SUL carrier relative to the first cell), or it can be a NUL carrier, or it can be other carriers.

[0407] In one possible implementation, when the second network device sends the first indication information, it may also include information indicating that the first carrier can be used as an uplink time resource. The information about the uplink time resource may include the uplink time slot, subframe position, and uplink and downlink time slot ratio. This facilitates the terminal device to obtain the configuration information of the first carrier in advance.

[0408] 407. The second network device sends the first information to the terminal device.

[0409] Correspondingly, the terminal device can receive the first information sent by the second network device.

[0410] After the terminal device determines that the carrier for uplink transmission in the first cell is the first carrier, it can receive first information sent by the second network device. The first information may include the TA offset value of the first cell, and may also include at least one of the time slot offset value between the first cell and the second cell, the system frame number offset value between the first cell and the second cell, and the frame boundary offset value between the first cell and the second cell.

[0411] 408. The terminal device determines a first TA value.

[0412] After the terminal device receives the first information sent by the second network device, it can determine the first TA value according to the first information, the transmission timing of the terminal device on the second carrier, the downlink timing of the first cell and the TA offset value of the first cell. Since the carrier for uplink transmission in the first cell is the first carrier, that is, before and after the switching, the terminal device sends uplink transmissions in the second cell and the first cell using the carrier of the same frequency band, and the uplink transmissions sent by the terminal device on the first carrier and the second carrier are received by the same network device, so the transmission timing of the uplink transmission sent by the terminal device should remain unchanged. When switching from the second cell to the first cell, when performing uplink transmission in the first cell, the terminal device needs to refer to the downlink timing of the first cell, and no longer needs to refer to the downlink timing of the second cell, so the TA value of the terminal device on the first carrier needs to be adjusted accordingly. Specifically, the first information can be sent from the second network device to the terminal device, the transmission timing on the second carrier is determined by the terminal device, and the downlink timing of the first cell can be obtained by the terminal device by detecting the synchronization signal block (synchronization signal / PBCH block, SSB) information or other reference signals of the first cell. Therefore, the terminal device can determine the first TA value based on the first information, the transmission timing of the second carrier, the downlink timing of the first cell and the TA offset value of the first cell, thereby achieving uplink synchronization of the terminal device on the first carrier of the first cell.

[0413] If after the terminal device switches to the first cell, the uplink carrier is only the first carrier, then determining the TA value of the terminal device on the first carrier can also be understood as determining the TA value of the terminal device in the first cell; if after the terminal device switches to the first cell, the uplink carrier has the first carrier and other carriers, and when the TA values ​​of the first carrier and other carriers are the same, determining the TA value of the terminal device on the first carrier can also be understood as determining the TA value of the terminal device in the first cell.

[0414] The first carrier and the second carrier can be uplink carriers. In one possible implementation, if the carrier is an uplink carrier, then the transmission timing of the terminal device on the carrier can be understood as the uplink timing of the terminal device on the carrier. For example, the transmission timing of the terminal device on the second carrier can be understood as the uplink timing of the terminal device on the second carrier. The first TA value is the TA value of the terminal device on the first carrier. In this way, the TA value on the first carrier can be determined without random access, thereby achieving uplink synchronization of the terminal device on the first carrier of the first cell.

[0415] Specifically, the first TA value may satisfy the following formula:

[0416]

[0417] Among them, N TA is the first TA value, T is the downlink timing of the first cell, T tt is the sending timing of the terminal device on the second carrier, T C =1 / (Δf max ·N f ), Δf max =480·10 3 Hz and N f =4096, N TA-offset is the TA offset value of the first cell.

[0418] In one possible implementation, N TA-offset is the TA offset value of the first carrier and the downlink carrier of the first cell.

[0419] The first TA value can also satisfy the following formula:

[0420] or

[0421] Among them, T slot-offset is the time slot offset value between the first cell and the second cell.

[0422] The first TA value can also satisfy the following formula:

[0423] or

[0424] Among them, T sfn-offset is the system frame number offset value between the first cell and the second cell.

[0425] The first TA value can also satisfy the following formula:

[0426] or

[0427] The first TA value can also satisfy the following formula:

[0428] or Among them, T Fb-offset is the frame boundary offset value between the first cell and the second cell.

[0429] In one possible implementation, see Figure 5 , Figure 5 This is another diagram of the relationship between the uplink and downlink timing of data provided in the embodiment of the present application. Figure 5 As shown, the terminal device sends an uplink frame on the first carrier, and can be T before the start position of the downlink frame corresponding to the uplink frame TA =(N TA +N TA-offset )×T C Start (the downlink frame is the downlink frame corresponding to the uplink frame in the first cell), which can also be understood as the difference between the transmission timing of the terminal device on the first carrier and the downlink timing of the first cell is (N TA +N TA-offset )×T C . That is, the transmission timing of the terminal device on the first carrier is consistent with the starting position of the uplink frame sent by the terminal device on the first carrier; the downlink timing of the terminal device in the first cell is consistent with the starting position of the downlink frame corresponding to the uplink frame sent by the terminal device on the first carrier. Therefore, after switching, the TA value of the terminal device on the first carrier can be calculated by the starting time of the uplink frame sent by the terminal device on the second carrier and the starting time of the downlink frame corresponding to the uplink frame in the first cell.

[0430] Specifically, the formula for the first TA value may also be:

[0431]

[0432] Among them, S is the starting time of the uplink frame sent by the terminal device on the second carrier, and T1 can be the starting time of the downlink frame corresponding to the uplink frame in the first cell. For example, if the frame number of the uplink frame is i, the frame number of the downlink frame corresponding to the uplink frame in the first cell can be i, or it can be i+j, and j can be notified to the terminal device by the second network device or the first network device. For another example, the downlink frame corresponding to the uplink frame in the first cell can be the downlink frame with the smallest difference between the starting time and the sending starting time of the uplink frame i of the first carrier, or it can be the downlink frame with the smallest difference between the starting time and the sending starting time of the uplink frame i+j of the first carrier, and j can be notified to the terminal device by the second network device or the first network device, or it can be determined by the terminal device.

[0433] The first TA value can also satisfy the following formula:

[0434] or

[0435] The first TA value can also satisfy the following formula:

[0436] or

[0437] The first TA value can also satisfy the following formula:

[0438] or

[0439] The first TA value can also satisfy the following formula:

[0440] or

[0441] In one possible implementation, the second network device sends sixth indication information to the terminal device, where the sixth indication information is used to indicate a first TA value. After receiving the sixth indication information, the terminal device may skip random access during the handover process, and the terminal device may determine, based on the TA value in the sixth indication information, that after handover to the first cell, the first TA value is the TA value in the sixth indication information, or the terminal device may determine, based on the TA value in the sixth indication information, that after handover to the first cell, the first TA value is the TA value of the second carrier, or the terminal device may determine, based on the TA value in the sixth indication information, that after handover to the first cell, the first TA value is determined based on the first information, the terminal device's transmit timing on the second carrier, and the downlink timing of the first cell.

[0442] 409. The second network device sends third indication information to the terminal device, which is used to indicate whether the second TA value is the same as the first TA value.

[0443] Correspondingly, the terminal device can receive third indication information sent by the second network device to indicate whether the second TA value is the same as the first TA value.

[0444] The second network device can send third indication information to the terminal device, and the third indication information can be used to indicate whether the second TA value is the same as the first TA value. The second TA value is the TA value of the terminal device in the fourth carrier, and the fourth carrier is a carrier of the terminal device in the first cell that is different from the first carrier.

[0445] In a possible implementation, the third indication information may also be used to indicate whether the fourth carrier and the first carrier are co-located.

[0446] In a possible implementation, the third indication information may also be used to indicate a second TA value.

[0447] 410. The terminal device determines a second TA value.

[0448] The terminal device may determine the second TA value according to the third indication information, specifically:

[0449] When the third indication information indicates that the second TA value is the same as the first TA value, it can be determined that the second TA value is the first TA value.

[0450] When the third indication information indicates that the fourth carrier is co-located with the first carrier, the second TA value may be determined to be the first TA value.

[0451] The second network device may determine the second TA value based on information about whether the second TA value is the same as the first TA value or whether the fourth carrier and the first carrier are co-located, and then send the second TA value to the terminal device through third indication information.

[0452] In one embodiment, the fourth carrier may be a SUL carrier or a NUL carrier. The first and fourth carriers may also be adapted for 5G and 6G. It should be understood that the names of all carriers in this application are merely examples. In future communications, such as 6G, other names may be used, and this application does not limit this. This is explained here for a unified explanation and will not be repeated later.

[0453] It should be understood that in the embodiment of the present application, part or all of the first information, first indication information, second indication information, third indication information, fourth indication information, fifth indication information and sixth indication information can be carried in the RRC message or PDCCH message, and part or all of this information can be sent simultaneously by the second network device to the terminal device, or can be sent in a chronological order. This application does not limit this.

[0454] 411. The terminal device sends second information to the first network device.

[0455] Correspondingly, the first network device can receive the second information sent by the terminal device.

[0456] In one embodiment, after the terminal device determines the TA value of at least one carrier of the first cell, the terminal device may send the second information on the at least one carrier according to the corresponding TA value. Specifically:

[0457] A terminal device communicates with a first network device in a first cell. The first network device can send downlink transmissions to the terminal device. After determining a first TA value, the terminal device can send second information on a first carrier based on the first TA value. The terminal device can send uplink transmissions to a fourth network device on the first carrier of the first cell based on the first TA value. The fourth network device is a network device that can receive uplink transmissions sent by the terminal device on the second carrier. The fourth network device then sends the uplink transmission data to the first network device. For example, the fourth network device can send the uplink transmission data to the first network device via a backhaul. If the first network device is the fourth network device, that is, the second carrier is co-located with the first cell, or the second carrier is co-located with the first network device, then the terminal device can directly continue to send uplink transmissions to the first network device on the second carrier. The uplink transmission information can be the second information, which is used to confirm a handover to the first network device. The handover confirmation can be confirming the handover of the terminal device from the second cell to the first cell. In this way, the terminal device can achieve uplink synchronization on the first carrier of the first cell without random access, thereby improving communication efficiency.

[0458] The terminal device may maintain the first TA value and continue to send uplink transmissions to the fourth network device or the first cell on the second carrier until the first network device or the first cell sends a message to the terminal device for modifying the first TA value.

[0459] A terminal device communicates with a first network device in a first cell, and the first network device can send a downlink transmission to the terminal device. After the terminal device determines a second TA value, it can send second information on a fourth carrier based on the second TA value. The terminal device can send an uplink transmission on a fourth carrier to a sixth network device based on the second TA value. The sixth network device refers to a network device that can receive uplink transmissions sent by the terminal device on the fourth carrier. The sixth network device then sends the uplink transmission data to the first network device. If the first network device is the sixth network device, that is, if the fourth carrier and the first cell are co-located, or if the fourth carrier and the first network device are co-located, then the terminal device can send an uplink transmission on the fourth carrier to the first network device. The uplink transmission information can be the second information, which is used to confirm the handover to the first network device. In this way, the terminal device can achieve uplink synchronization of the terminal device on the fourth carrier of the first cell without random access, which can improve communication efficiency.

[0460] The terminal device can maintain the second TA value and send uplink transmission information to the sixth network device or the first cell on the fourth carrier until the first network device or the first cell sends a message for modifying the second TA value to the terminal device.

[0461] For another example, the terminal device may simultaneously send uplink transmission information to the fifth network device or the first cell on the first carrier and to the sixth network device or the first cell on the fourth carrier based on the first TA value and the second TA value.

[0462] In one embodiment, after the terminal device is switched, if the first carrier and the fourth carrier are not at the same site, the transmission paths of the first carrier and the fourth carrier are different, the distances between the terminal device and the fourth network device and the sixth network device are different, and the first TA value and the second TA value are independent. Therefore, the first TA value and the second TA value need to be independently indicated and / or adjusted. The terminal device can adjust the first TA value and the second TA value respectively through two signalings sent by the first network device or the first cell, or can adjust the first TA value and the second TA value respectively through different fields of a signaling sent by the first network device or the first cell.

[0463] In one possible implementation, the terminal device may assist the fourth network device in adjusting the first TA value by sending a periodic signal to the fourth network device; the terminal device may assist the sixth network device in adjusting the second TA value by sending a periodic signal to the sixth network device.

[0464] In one embodiment, the second information may be an RRC reconfiguration complete message. The terminal device synchronizes to the first cell and completes the handover process by sending the RRC reconfiguration complete message to the fourth network device or the sixth network device.

[0465] Correspondingly, after receiving the second information, the first network device can send a reconfiguration completion response to the terminal device. The response message can also be used to instruct the terminal device to no longer use the semi-static uplink resources.

[0466] Based on the above network architecture, please refer to Figure 6 , Figure 6 This is a flow chart of another communication method provided by an embodiment of the present application. Among them, the functions performed by the terminal device in the present application can also be performed by a module (for example, a chip) in the terminal device, the functions performed by the first network device in the present application can also be performed by a module (for example, a chip) in the first network device, and the functions performed by the second network device in the present application can also be performed by a module (for example, a chip) in the second network device. Figure 6 As shown, the communication method may include the following steps.

[0467] 601. A second network device sends a measurement configuration to a terminal device.

[0468] It should be understood that step 601 corresponds to step 401. For the relevant description of step 601, reference can be made to the description of step 401 above. To avoid repetition, details will not be given here.

[0469] 602. The terminal device determines a measurement result of the fifth cell according to the measurement configuration.

[0470] After receiving the measurement configuration sent by the second network device, the terminal device can measure the second cell and can also determine whether it is necessary to perform measurement on adjacent cells based on the RRC message.

[0471] The terminal device may determine the measurement result of the fifth cell based on the measurement configuration. The fifth cell includes the cell corresponding to the measurement configuration, and may include the second cell, or may include a cell adjacent to the second cell. The measurement result of the fifth cell may include the measurement result of the second cell, or may include the measurement result of the adjacent cell. The measurement result may include RSRP, RSRQ, and SINR.

[0472] 603. The second network device sends information about the third cell to the terminal device.

[0473] Correspondingly, the terminal device can receive the information of the third cell sent by the second network device.

[0474] In one possible implementation, after the terminal device determines the measurement result of the fifth cell based on the measurement configuration, it may not report the measurement result of the fifth cell to the second network device. Instead, the terminal device determines whether handover is required based on the measurement result of the fifth cell. If handover is required, the terminal device may obtain information about the third cell from the second network device. The third cell may be at least one cell in the fifth cell, and the effective carrier of the third cell may be the same as the effective carrier of the second cell. In one embodiment, an acquisition request message for obtaining information about the third cell may be sent to the second network device to obtain information about the third cell. For information about the third cell, reference may be made to the description in step 403 and will not be repeated here.

[0475] The third cell information can be sent from the second network device to the terminal device via a system message or proprietary signaling. The system message can be an on-demand system message. If the third cell information is sent to the terminal device via an on-demand system message, the system message is not always broadcast. Instead, the terminal device sends a request message to the second network device only when it needs the third cell information, thus reducing interference.

[0476] It should be understood that in an embodiment of the present application, the second network device may send the information of the third cell to the terminal device before sending the measurement configuration, at the same time as the measurement configuration, or after sending the measurement configuration. This application does not limit this.

[0477] If the third cell information is sent by the second network device before the measurement configuration is sent to the terminal device, it can be understood that the terminal device can obtain the third cell information not only during handover but also before receiving the measurement configuration for other services or needs. In this way, the terminal device does not need to obtain the third cell information during handover and can directly use the third cell information, which can reduce the terminal device's received signaling and improve handover efficiency.

[0478] If the information of the third cell and the measurement configuration are sent by the second network device to the terminal device at the same time, the reception signaling of the terminal device can be reduced and the switching efficiency can be improved.

[0479] If the third cell information is sent after the second network device sends the measurement configuration to the terminal device, it can be understood that when the terminal device needs to use the third cell information during switching, it obtains it from the second network device on demand, which can avoid wasting resource storage space of the terminal device.

[0480] In one embodiment, the acquisition request message can also be used to obtain a time slot ratio. The terminal device can obtain the time slot ratio of the third cell in advance through the acquisition request message. The terminal device can obtain the time slot ratio when obtaining information about the third cell, or can obtain the time slot ratio from the second network device before the terminal device determines that the carrier for uplink transmission in the first cell is the first carrier. This application is not limited to this.

[0481] In one possible implementation, the terminal device determines a measurement result of the fifth cell based on the measurement configuration and reports it to the second network device. The second network device may then decide to hand over the terminal device based on the measurement result of the fifth cell. If handover is required, the second network device sends a handover instruction and information about the third cell to the terminal device. For specific steps, refer to the description of step 403 and are not repeated here.

[0482] In one embodiment, the information of the third cell may further include a value L1 or L2 specified by the second network device, where L1 and L2 are positive integers greater than or equal to 1. The information of the third cell may have at least one value L1 or at least one L2.

[0483] The value L1 can represent that there is a carrier that is co-located with the second carrier among the effective carriers of the first L1 cells in the third cell. For example, as shown in Table 1, if carrier 1 is co-located with the second carrier or carrier 1 refers to the second carrier, and there is carrier 1 in cells 1, cell 2, ..., cell 5, the value L1 can represent that there is a carrier that is co-located with the second carrier among the effective carriers of the first L1 cells in cells 1, cell 2, ..., cell 5. If the value L1=1, it can indicate that there is a carrier that is co-located with the second carrier among the effective carriers of the first cell in cells 1, cell 2, ..., cell 5, that is, there is a carrier that is co-located with the second carrier among the effective carriers of cell 1; if the value L=2, it can indicate that there is a carrier that is co-located with the second carrier among the effective carriers of the first two cells in cells 1, cell 2, ..., cell 5, that is, there is a carrier that is co-located with the second carrier among the effective carriers of cells 1 and cell 2. Because there are n carriers in Table 1, there can be at least one value L1.

[0484] The value L2 can also represent that the first L2 carriers of a cell in the third cell are co-located with the cell. If the second carrier is in the first L2 carriers, it can be said that the cell is co-located with the second carrier. For example, as shown in Table 2, the value L2 can represent that the first L2 carriers of each cell in the third cell are co-located with the cell. It can be understood that the first L2 carriers of carrier 1, carrier 2, ..., carrier 5 are co-located with cell 1. If the second carrier exists in the first L2 carriers, it can be determined that cell 1 is co-located with the second carrier. It can also be understood that the first L2 carriers of carrier 1, carrier 6, ..., carrier 10 are co-located with cell 2. If the second carrier exists in the first L2 carriers, it can be determined that cell 2 is co-located with the second carrier. ...; and so on. Because there are n cells in Table 2, there can be at least one value L2.

[0485] The value L may not be specified in the information of the first cell sent by the first network device. It may be predefined in the protocol to default to the presence of a carrier that is co-located with the second carrier among the valid carriers of the first or first few cells, or to default to which one or several cells are co-located with the second carrier.

[0486] In one embodiment, when the second network device transmits information about the third cell to the terminal device, it may also transmit a time slot ratio. The terminal device can obtain the time slot ratio of the first cell in advance, and the second network device can accordingly reduce the number of bits in the instruction notifying the terminal device to perform a handover. The third cell information can be carried in an RRC message or a PDCCH message and sent to the terminal device via the second network device.

[0487] 604. The terminal device determines N fourth cells according to the information of the third cell and the measurement result of the third cell.

[0488] After receiving the information about the third cell sent by the second network device, the terminal device may determine N fourth cells based on the information about the third cell and the measurement result of the third cell. The fourth cell may be a candidate cell, where N is an integer greater than or equal to 1. The terminal device determines the N fourth cells based on the information about the third cell and the measurement result of the third cell. Reference may be made to the description of the second network device determining the first cell based on the information about the third cell and the measurement result of the third cell in step 403, and no further description is given here.

[0489] 605. The terminal device sends indication information of N fourth cells to the second network device.

[0490] Correspondingly, the second network device can receive indication information of N fourth cells sent by the terminal device.

[0491] After the terminal device determines N fourth cells based on the information of the third cell and the measurement result of the third cell, it can report indication information of the N fourth cells to the second network device based on its own capabilities and / or business needs.

[0492] In a possible implementation, when the terminal device reports indication information of N fourth cells to the second network device, it may also report measurement results of the N fourth cells.

[0493] In a possible implementation, when the terminal device reports indication information of N fourth cells to the second network device, it may also report the measurement result of the fifth cell.

[0494] 606. The second network device determines the first cell according to the indication information of the N fourth cells.

[0495] After the second network device receives the indication information of the N fourth cells sent by the terminal device, it can determine a first cell from the N fourth cells.

[0496] In a possible implementation, N may be 1, and the second network device receives information about a cell sent by the terminal device, and can then determine that the first cell is this cell.

[0497] In a possible implementation, N may be an integer greater than 1, and the second network device receives information of multiple cells sent by the terminal device, and further determines the first cell from the multiple cells. Specifically:

[0498] The second network device may determine the first cell according to the total value of each cell in the N fourth cells, and may use the cell with the highest total value among the N fourth cells as the first cell.

[0499] Since the effective carrier of the third cell has at least one identical carrier with the effective carrier of the second cell, N fourth cells are determined based on the measurement results of the third cell and the information of the third cell, which can ensure that the effective carrier of each of the N fourth cells has the same carrier as the effective carrier of the second cell. Then, the second network device determines a first cell from the N fourth cells, which can ensure that the terminal device determines that the carrier for uplink transmission in the first cell is the first carrier, so that the terminal device does not need random access during the switching process, and the uplink synchronization of the terminal device on the first carrier of the first cell is achieved, which can improve the efficiency of communication.

[0500] 607. The second network device sends a request message to the first network device for requesting the terminal device to access the first network device.

[0501] Correspondingly, the first network device may receive the request information sent by the second network device for requesting the terminal device to access the first network device.

[0502] After the second network device determines the first cell based on the indication information of the N fourth cells, it can send a request message to the first network device requesting the terminal device to access the first network device. For a detailed description, please refer to the description of step 404, which will not be repeated here.

[0503] 608. The second network device sends second indication information for indicating information of the first cell to the terminal device.

[0504] It should be understood that step 608 corresponds to step 405. For the relevant description of step 608, reference can be made to the description of step 405 above. To avoid repetition, details will not be given here.

[0505] 609. Determine that after the terminal device switches from the second cell to the first cell, the carrier for uplink transmission by the terminal device in the first cell is the first carrier.

[0506] It should be understood that step 609 corresponds to step 406. For the relevant description of step 609, reference can be made to the description of step 406 above. To avoid repetition, details will not be given here.

[0507] 610. The second network device sends first information to the terminal device.

[0508] It should be understood that step 610 corresponds to step 407. For the relevant description of step 610, reference can be made to the description of step 407 above. To avoid repetition, details will not be given here.

[0509] 611. The terminal device determines a first TA value.

[0510] It should be understood that step 611 corresponds to step 408 , and the relevant description in step 611 can refer to the description of the above step 408 , which will not be repeated here to avoid repetition.

[0511] 612. The second network device sends third indication information to the terminal device, which is used to indicate whether the second TA value is the same as the first TA value.

[0512] It should be understood that step 612 corresponds to step 409. For the relevant description of step 612, reference can be made to the description of step 409 above. To avoid repetition, details will not be given here.

[0513] 613. The terminal device determines a second TA value.

[0514] It should be understood that step 613 corresponds to step 410. For the relevant description of step 613, reference can be made to the description of step 410 above. To avoid repetition, details will not be given here.

[0515] 614. The terminal device sends second information to the first network device.

[0516] It should be understood that step 614 corresponds to step 411 , and the relevant description in step 614 can refer to the description of the above step 411 , which will not be repeated here to avoid repetition.

[0517] Based on the above network architecture, please refer to Figure 7 , Figure 7 This is a flow chart of another communication method provided by an embodiment of the present application. Among them, the functions performed by the terminal device in the present application can also be performed by a module (for example, a chip) in the terminal device, the functions performed by the first network device in the present application can also be performed by a module (for example, a chip) in the first network device, and the functions performed by the second network device in the present application can also be performed by a module (for example, a chip) in the second network device. Figure 7 As shown, the communication method may include the following steps.

[0518] 701. A second network device sends a measurement configuration to a terminal device.

[0519] It should be understood that step 701 corresponds to step 401. For the relevant description of step 701, reference can be made to the description of step 401 above. To avoid repetition, details will not be given here.

[0520] 702. The terminal device sends the measurement result of the fifth cell to the second network device.

[0521] It should be understood that step 702 corresponds to step 402. For the relevant description of step 702, reference can be made to the description of step 402 above. To avoid repetition, details will not be given here.

[0522] 703. The second network device determines the first cell according to the information of the third cell and the measurement result of the third cell.

[0523] It should be understood that step 703 corresponds to step 403. For the relevant description of step 703, reference can be made to the description of step 403 above. To avoid repetition, details will not be given here.

[0524] 704. The second network device sends a request message to the first network device for requesting the terminal device to access the first network device.

[0525] It should be understood that step 704 corresponds to step 404. For the relevant description of step 704, reference can be made to the description of step 404 above. To avoid repetition, details will not be given here.

[0526] 705. The second network device sends second indication information for indicating information of the first cell to the terminal device.

[0527] It should be understood that step 705 corresponds to step 405. For the relevant description of step 705, reference can be made to the description of step 405 above. To avoid repetition, details will not be given here.

[0528] 706. The second network device sends third information to the terminal device.

[0529] Correspondingly, the terminal device receives the third information sent by the second network device.

[0530] The third information may include first indication information and the ID of the first cell. The first indication information may be used to instruct the terminal device to continue sending uplink transmissions to the fourth network device. The terminal device may determine which first cell to switch to based on the ID of the first cell. The terminal device may also determine, based on the first indication information, to continue sending uplink transmissions in the first cell to the fourth network device. The fourth network device is a network device that can receive uplink transmissions sent by the terminal device in the second cell.

[0531] Before the terminal device switches, it communicates with the second network device in the second cell. The second network device can send downlink transmissions to the terminal device, and the terminal device can send uplink transmissions to the fourth network device. The fourth network device refers to a network device that can receive uplink transmissions sent by the terminal device in the second cell. The fourth network device then sends the uplink transmission data to the second network device. For example, the fourth network device can send the uplink transmission data to the second network device via a backhaul. If the second network device is the fourth network device, that is, the fourth network device and the second network device are co-located, then the terminal device can send uplink transmissions directly to the second network device. After the terminal device switches, it communicates with the first network device in the first cell. The first network device can send downlink transmissions to the terminal device, and the terminal device can send uplink transmissions to the fifth network device. The fifth network device refers to a network device that can receive uplink transmissions sent by the terminal device in the first cell. The fifth network device then sends the uplink transmission data to the first network device. For example, the fifth network device can send the uplink transmission data to the first network device via a backhaul. If the first network device is the fifth network device, that is, the fifth network device and the first network device are co-located, then the terminal device can directly send uplink transmission to the first network device.

[0532] Continuing to send uplink transmissions to the fourth network device can be understood as, before and after the terminal device switches, in the second cell and the first cell, it can send uplink transmissions to the same network device, that is, the fourth network device. Specifically: after the terminal device switches, it communicates with the first network device in the first cell, the first network device can send downlink transmissions to the terminal device, the terminal device can continue to send uplink transmissions to the fourth network device, and the fourth network device then sends the uplink transmission data to the first network device. For example, the fourth network device can send the uplink transmission data to the first network device via the backhaul. If the first network device is the fourth network device, then the terminal device can send uplink transmissions directly to the first network device. In this way, the terminal device can send uplink transmissions in the first cell without random access. Therefore, the solution provided by the present application can effectively avoid the delay and interruption problems that may occur during the switching process of the terminal device to the first cell that requires random access, and can improve the efficiency of communication.

[0533] In one embodiment, the second network device may send fourth indication information to the terminal device, and the fourth indication information may be used to indicate whether the terminal device skips random access during the switching process. When the fourth indication information indicates that the terminal device skips random access during the switching process, the terminal device may determine to continue to send uplink transmission to the fourth network device in the first cell based on the first indication information.

[0534] In one possible implementation, when the second network device transmits the third information, it may also include information about time resources for continuing to transmit uplink transmission to the fourth network device. The time resource information may include the uplinked time slot, subframe position, and uplink and downlink time slot ratio. This facilitates the terminal device to obtain configuration information in advance.

[0535] 707. The second network device sends the first information to the terminal device.

[0536] It should be understood that step 707 corresponds to step 407. For the relevant description of step 707, reference can be made to the description of step 407 above. To avoid repetition, details will not be given here.

[0537] 708. The terminal device determines a first TA value.

[0538] After the terminal device receives the first information sent by the second network device, it can determine the first TA value based on the first information, the first sending timing, the downlink timing of the first cell and the TA offset value of the first cell, and the first TA value is used to continue sending uplink transmission to the fourth network device.

[0539] It should be understood that step 708 corresponds to step 408. The description of determining the first TA value in step 708 can be found in the description of step 408 above, and will not be repeated here to avoid repetition.

[0540] It should be understood that the T in step 408 tt The terminal device transmits the second carrier at the timing. In step 708, T tt The first sending timing may be the sending timing at which the terminal device sends uplink transmission in the second cell. The first sending timing may also be referred to as the first uplink timing.

[0541] Since the terminal device can continue to send uplink transmissions to the fourth network device in the first cell, that is, before and after the handover, the terminal device can send uplink transmissions to the same network device, namely, the fourth network device, in the second cell and the first cell, the transmission timing of the uplink transmissions by the terminal device should remain unchanged. When switching from the second cell to the first cell, when performing uplink transmissions in the first cell, the terminal device needs to refer to the downlink timing of the first cell and no longer needs to refer to the downlink timing of the second cell. Therefore, the TA value based on which the terminal device continues to send uplink transmissions to the fourth network device, namely, the first TA value, needs to be adjusted accordingly.

[0542] Specifically, the first information may be sent from the second network device to the terminal device, the first transmission timing is determined by the terminal device, and the downlink timing of the first cell can be obtained by the terminal device by detecting the SSB information or other reference signal of the first cell. Therefore, the terminal device can determine the first TA value based on the first information, the first transmission timing, the downlink timing of the first cell, and the TA offset value of the first cell. In this way, the first TA value can be determined without random access, thereby achieving uplink synchronization of the terminal device in the first cell, which can improve communication efficiency.

[0543] It should be understood that in the embodiments of the present application, part or all of the first information, third information, second indication information, fourth indication information, and sixth indication information may be carried in an RRC message or a PDCCH message, and part or all of this information may be sent simultaneously by the second network device to the terminal device, or may be sent in a chronological order. This application does not limit this.

[0544] 709. The terminal device sends uplink transmission information.

[0545] When the fourth network device is the first network device, the terminal device may send uplink transmission information to the first network device; or when the fourth network device is the second network device, the terminal device may send uplink transmission information to the second network device. The uplink transmission information may include second information, and the second information is used to confirm the handover to the first network device. Confirming the handover may refer to the terminal device switching from the second cell to the first cell.

[0546] Specifically, before and after the handover, the terminal device can send uplink transmissions to the same network device, i.e., the fourth network device, in both the second cell and the first cell. If the fourth network device is the second network device, the terminal device can directly send uplink transmissions to the second network device; if the fourth network device is the first network device, the terminal device can directly send uplink transmissions to the first network device.

[0547] In one embodiment, the terminal device may also send uplink transmissions based on the first TA value. In this way, uplink synchronization of the terminal device in the first cell can be achieved without random access. Therefore, the solution provided by this application can effectively avoid delays and interruptions that may occur during a handover of the terminal device to the first cell that requires random access, thereby improving communication efficiency.

[0548] The terminal device may maintain the first TA value and continue to send uplink transmission information to the fourth network device until the first network device or the first cell sends a message for modifying the first TA value to the terminal device.

[0549] In a possible implementation, the terminal device may assist the fourth network device in adjusting the first TA value by sending a periodic signal to the fourth network device.

[0550] In one embodiment, the second information may be an RRC reconfiguration complete message. The terminal device synchronizes to the first cell and completes the handover process by sending the RRC reconfiguration complete message to the fourth network device.

[0551] Correspondingly, after receiving the second information, the first network device can send a reconfiguration completion response to the terminal device. The response message can also be used to instruct the terminal device to no longer use the semi-static uplink resources.

[0552] Based on the above network architecture, please refer to Figure 8 , Figure 8 This is a flow chart of another communication method provided by an embodiment of the present application. The functions performed by the terminal device in the present application may also be performed by a module (e.g., a chip) in the terminal device, and the functions performed by the first network device in the present application may also be performed by a module (e.g., a chip) in the first network device. Figure 8 As shown, the communication method may include the following steps.

[0553] 801. A second network device sends a measurement configuration to a terminal device.

[0554] It should be understood that step 801 corresponds to step 701. For the relevant description of step 801, reference can be made to the description of step 701 above. To avoid repetition, details will not be given here.

[0555] 802. The terminal device determines a measurement result of the fifth cell according to the measurement configuration.

[0556] It should be understood that step 802 corresponds to step 602. For the relevant description of step 802, reference can be made to the description of step 602 above. To avoid repetition, details will not be given here.

[0557] 803. The second network device sends information about the third cell to the terminal device.

[0558] It should be understood that step 703 corresponds to step 603, and the relevant description in step 803 can refer to the description of the above step 603. In order to avoid repetition, it will not be repeated here.

[0559] 804. The terminal device determines N fourth cells based on the information of the third cell and the measurement result of the third cell.

[0560] It should be understood that step 804 corresponds to step 604. For the relevant description of step 804, reference can be made to the description of step 604 above. To avoid repetition, details will not be given here.

[0561] 805. The terminal device sends indication information of N fourth cells to the second network device.

[0562] It should be understood that step 805 corresponds to step 605. For the relevant description of step 805, reference can be made to the description of step 605 above. To avoid repetition, details will not be given here.

[0563] 806. The second network device determines the first cell according to the indication information of the N fourth cells.

[0564] It should be understood that step 806 corresponds to step 606. For the relevant description of step 806, reference can be made to the description of step 606 above. To avoid repetition, details will not be given here.

[0565] 807. The second network device sends a request message to the first network device for requesting the terminal device to access the first network device.

[0566] It should be understood that step 807 corresponds to step 607. For the relevant description of step 807, reference can be made to the description of step 607 above. To avoid repetition, details will not be given here.

[0567] 808. The second network device sends second indication information for indicating information of the first cell to the terminal device.

[0568] It should be understood that step 808 corresponds to step 705. For the relevant description of step 808, reference can be made to the description of step 705 above. To avoid repetition, details will not be given here.

[0569] 809. The second network device sends third information to the terminal device.

[0570] It should be understood that step 809 corresponds to step 706. For the relevant description of step 809, reference can be made to the description of step 706 above. To avoid repetition, details will not be given here.

[0571] 810. The second network device sends first information to the terminal device.

[0572] It should be understood that step 810 corresponds to step 707. For the relevant description of step 810, reference can be made to the description of step 707 above. To avoid repetition, details will not be given here.

[0573] 811. The terminal device determines a first TA value.

[0574] It should be understood that step 811 corresponds to step 708. For the relevant description of step 811, reference can be made to the description of step 708 above. To avoid repetition, details will not be given here.

[0575] 812. The terminal device sends uplink transmission information.

[0576] It should be understood that step 812 corresponds to step 709. For the relevant description of step 811, reference can be made to the description of step 709 above. To avoid repetition, details will not be given here.

[0577] Based on the above network architecture, please refer to Figure 9 , Figure 9 This is a flow chart of another communication method provided by an embodiment of the present application. Among them, the functions performed by the terminal device in the present application can also be performed by a module (for example, a chip) in the terminal device, the functions performed by the first network device in the present application can also be performed by a module (for example, a chip) in the first network device, and the functions performed by the second network device in the present application can also be performed by a module (for example, a chip) in the second network device. Figure 9 As shown, the communication method may include the following steps.

[0578] 901. A second network device sends a measurement configuration to a terminal device.

[0579] It should be understood that step 901 corresponds to step 401. For the relevant description of step 901, reference can be made to the description of step 401 above. To avoid repetition, details will not be given here.

[0580] 902. The terminal device sends the measurement result of the fifth cell to the second network device.

[0581] It should be understood that step 902 corresponds to step 402. For the relevant description of step 902, reference can be made to the description of step 402 above. To avoid repetition, details will not be given here.

[0582] 903. The second network device determines the first cell according to the information of the third cell and the measurement result of the fifth cell.

[0583] After the second network device receives the measurement result of the fifth cell sent by the terminal device, it can first determine whether there is a third cell in the fifth cell. The third cell can be a cell that has at least one carrier in the valid carrier that is the same as the valid carrier of the second cell. When the third cell exists in the fifth cell, the first cell can be determined based on the information of the third cell and the measurement result of the third cell. The information of the third cell is known to the second network device. Since the third cell is at least one cell in the fifth cell, the measurement result of the third cell can be obtained from the measurement result of the fifth cell reported by the terminal device. Therefore, the second network device can determine the first cell based on the measurement result of the third cell and the information of the third cell; when the third cell does not exist in the fifth cell, the first cell can be determined based on the measurement result of the fifth cell. Specifically:

[0584] In one possible implementation, when there is a third cell in the fifth cell, the second network device may preferentially select a cell in the third cell as the first cell. For specific determination of the first cell based on the information of the third cell and the measurement result of the third cell, please refer to the description of step 403 and will not be repeated here.

[0585] Compared with determining the first cell based only on the measurement results of the third cell and the information of the third cell, although the effective carrier of each cell in the third cell and the effective carrier of the second cell are the same carrier can be preferentially selected as the first cell, if the measurement results of each cell are not good, the first cell determined from the third cell does not meet the conditions for terminal device switching.

[0586] Therefore, if the measurement results of each cell in the third cell are relatively poor, the sixth cell can be selected and the first cell can be re-determined based on the measurement results of the sixth cell. The sixth cell can be a cell other than the third cell in the fifth cell. The sixth cell can include a cell whose effective carrier has no intersection with the effective carrier of the second cell, but has intersection with the effective carrier of other cells except the second cell. It can also include a cell whose effective carrier has no intersection with the effective carrier of the second cell and other cells except the second cell.

[0587] In one embodiment, the second network device preferentially selects a cell in the sixth cell whose effective carrier has no intersection with the effective carrier of the second cell, but has an intersection with the effective carriers of other cells except the second cell as the first cell. For example, some cells in the sixth cell have a SUL carrier in their effective carriers, and the SUL carrier is shared by other cells except the second cell, and some cells in the sixth cell do not have a SUL carrier in their effective carriers, then the second network device may preferentially select a cell with a SUL carrier in its effective carrier. Because if a cell without a SUL carrier in its effective carrier is selected as the first cell, the terminal device will not be able to use the SUL carrier for uplink continuity at the next switch. If a cell with a SUL carrier in its effective carrier is selected as the first cell, the terminal device can continue to use the SUL carrier for uplink continuity at the next switch, thereby avoiding delays and interruptions caused by random access during switching.

[0588] In a possible implementation, when the third cell does not exist in the fifth cell, the second network device may determine the first cell according to the measurement result of the fifth cell.

[0589] In one embodiment, the measurement result of the fifth cell may be quantified, and the first cell may be determined based on the measurement result value of each cell in the fifth cell. For example, the first cell may be the cell with the highest measurement result value.

[0590] In one embodiment, if the first cell is one of the third cells, the above-mentioned method of steps 404 to 411 or the method of steps 704 to 709 can also be executed, so that during the switching process, there is no need for random access, and the uplink synchronization of the terminal device in the first cell can be achieved, which can improve the efficiency of communication.

[0591] Based on the above network architecture, please refer to Figure 10 , Figure 10 This is another flow chart of a communication method provided by an embodiment of the present application. The functions performed by the terminal device in the present application may also be performed by a module (e.g., a chip) in the terminal device, and the functions performed by the first network device in the present application may also be performed by a module (e.g., a chip) in the first network device. Figure 10 As shown, the communication method may include the following steps.

[0592] 1001. A second network device sends a measurement configuration to a terminal device.

[0593] It should be understood that step 1001 corresponds to step 601. For the relevant description of step 1001, reference can be made to the description of step 601 above. In order to avoid repetition, it will not be repeated here.

[0594] 1002. The terminal device determines a measurement result of the fifth cell according to the measurement configuration.

[0595] It should be understood that step 1002 corresponds to step 602, and the relevant description in step 902 can refer to the description of the above step 602, which will not be repeated here to avoid repetition.

[0596] 1003. The second network device sends information about the third cell to the terminal device.

[0597] It should be understood that step 1003 corresponds to step 603. For the relevant description of step 1003, reference can be made to the description of step 603 above. In order to avoid repetition, it will not be repeated here.

[0598] 1004. The terminal device determines N fourth cells based on the information of the third cell and the measurement result of the fifth cell.

[0599] After the terminal device receives the information about the third cell sent by the second network device, it can first determine whether the third cell exists in the fifth cell. If the third cell exists in the fifth cell, N fourth cells can be determined based on the information about the third cell and the measurement result of the third cell. The information about the third cell is sent to the terminal device by the second network device. Since the third cell is at least one cell in the fifth cell, the measurement result of the third cell can be obtained from the measurement result of the fifth cell. Therefore, the terminal device can determine N fourth cells based on the measurement result of the third cell and the information about the third cell. If the third cell does not exist in the fifth cell, N fourth cells can be determined based on the measurement result of the fifth cell. Specifically:

[0600] In one possible implementation, when there is a third cell in the fifth cell, the terminal device can preferentially select cells in the third cell as N fourth cells. The specific determination of N fourth cells based on the information of the third cell and the measurement results of the third cell can refer to the description of step 604 and will not be repeated here.

[0601] Compared with determining N fourth cells based only on the measurement results of the third cell and the information of the third cell, although the effective carrier of each cell in the third cell has the same carrier as the effective carrier of the second cell, it can be preferentially selected as the N fourth cells, but if the measurement results of each cell are not good, the first cell determined from the N fourth cells does not meet the conditions for terminal device switching.

[0602] Therefore, if the measurement results of each cell in the third cell are relatively poor, the sixth cell can be selected, and N fourth cells can be re-determined based on the measurement results of the sixth cell. The sixth cell can be a cell other than the third cell in the fifth cell. The sixth cell can include a cell whose effective carrier has no intersection with the effective carrier of the second cell, but has intersection with the effective carrier of other cells except the second cell. It can also include a cell whose effective carrier has no intersection with the effective carrier of the second cell and other cells except the second cell.

[0603] In one embodiment, the terminal device preferentially selects cells in the sixth cell whose effective carrier has no intersection with the effective carrier of the second cell, but has intersection with the effective carriers of other cells except the second cell as N fourth cells. For example, some cells in the sixth cell have SUL carriers in their effective carriers, and the SUL carrier is shared by other cells except the second cell, and some cells in the sixth cell do not have SUL carriers in their effective carriers, then the terminal device may preferentially select cells with SUL carriers in their effective carriers as N fourth cells. Because the first cell is one of the N fourth cells, if a cell without SUL carriers in its effective carriers is selected as the N fourth cells, the terminal device will not be able to use the SUL carrier for uplink continuity during the next switching. If a cell with SUL carriers in its effective carriers is selected as the N fourth cells, the terminal device can continue to use the SUL carrier for uplink continuity during the next switching, thereby avoiding delays and interruptions caused by random access during switching.

[0604] In a possible implementation, when there is no third cell in the fifth cell, the terminal device may determine N fourth cells according to the measurement result of the fifth cell.

[0605] In one embodiment, the measurement result of the fifth cell may be quantified, and N fourth cells may be determined based on the measurement result value of each cell in the fifth cell. For example, the N fourth cells may be cells whose measurement result values ​​are greater than a certain threshold.

[0606] 1005. The terminal device sends indication information of N fourth cells to the second network device.

[0607] It should be understood that step 1005 corresponds to step 605. For the relevant description of step 1005, reference can be made to the description of step 605 above. To avoid repetition, details will not be given here.

[0608] 1006. The second network device determines the first cell according to the indication information of the N fourth cells.

[0609] It should be understood that step 1006 corresponds to step 606. For the relevant description of step 1006, reference can be made to the description of step 606 above. To avoid repetition, details will not be given here.

[0610] In one embodiment, if the first cell is one of the third cells, the above-mentioned method of steps 607 to 614 or the method of steps 704 to 709 can also be executed, so that during the switching process, there is no need for random access, and the uplink synchronization of the terminal device in the first cell can be achieved, which can improve the efficiency of communication.

[0611] Combine Figure 4 and Figure 6In one embodiment, see the communication method Figure 11 , Figure 11 This is a schematic diagram of a switching scenario provided by an embodiment of the present application. Figure 11 As shown, this scenario includes cells at Site 1 and Site 2, where a site can be understood as a station address. The cell at Site 1 has a NUL carrier and a corresponding DL carrier; the cell at Site 2 has a NUL carrier, a corresponding DL carrier, and a SUL carrier. The SUL carrier covers some or all of the cells at Site 1, meaning that some or all of the cells at Site 1 and the cells at Site 2 have the SUL carrier.

[0612] The terminal device switches from the cell of site 2 to the cell of site 1.

[0613] The cell at site 1 having the SUL carrier may be the first cell, and the cell at site 2 may be the second cell. The first cell may be obtained by executing steps 401 to 403 or steps 601 to 606. The network device at site 2 may be the second network device mentioned in the above method embodiment, and the network device at site 1 may be the first network device mentioned in the above method embodiment.

[0614] When the terminal device switches from the second cell to the first cell, it can be determined that the SUL carrier of the terminal device in the first cell is the SUL carrier of the terminal device in the second cell. That is, before and after the switch, the SUL carriers of the terminal device in the first cell and the second cell can be carriers of the same frequency band, and the uplink transmissions sent by the terminal device in the SUL carriers of the first cell and the second cell are received by the same network device. The terminal device can send uplink transmissions to the network device of site 2 on the SUL carrier. Specifically:

[0615] Before the terminal device switches, the SUL carrier of the second cell is co-located with the second cell. When the terminal device sends information to the network device of site 2 or the second cell via the SUL carrier of the second cell, the terminal device may send an uplink transmission including the information to the network device of site 2 or the second cell, and the network device of site 2 may send a downlink transmission to the terminal device.

[0616] After the terminal device is switched, the SUL carrier in the first cell and the first cell are at different sites. The information that the SUL carrier in the first cell and the first cell are at different sites can be notified to the terminal device by the network device of site 2 through an RRC message or a PDCCH message or a system message. For example, the system message can be an on-demand system message. Since the terminal device determines that the SUL carrier in the first cell is the SUL carrier of the terminal device in the second cell, when the terminal device sends information to the network device of site 1 or the first cell on the SUL carrier of the first cell, it can first send an uplink transmission including the information to the network device of site 2 on the SUL carrier of the first cell, and then the network device of site 2 sends the information to the network device of site 1 or the first cell. For example, the network device of site 2 can send the information to the network device of site 1 or the first cell through the backhaul, and the network device of site 1 can send a downlink transmission to the terminal device.

[0617] In one embodiment, when the network device at site 2 determines that the first TA value needs to be adjusted, the first TA value may be the TA value of the SUL carrier of the terminal device in the first cell. The adjustment amount of the first TA value may be sent to the network device at site 1 via the backhaul, and the network device at site 1 may send signaling to the terminal device to notify the terminal device to adjust the first TA value. The terminal device may assist the network device at site 2 in adjusting the first TA value by sending a periodic signal to the network device at site 2.

[0618] In one embodiment, when the network device at site 1 determines that the second TA value needs to be adjusted, the second TA value may be the TA value of the NUL carrier of the terminal device in the first cell. The network device at site 1 may send signaling to the terminal device to notify the terminal device to adjust the second TA value. The terminal device may assist the network device at site 1 in adjusting the second TA value by sending periodic signals to the network device at site 1.

[0619] Since the SUL carrier in the first cell and the first cell are at different sites, the NUL carrier in the first cell and the SUL carrier in the first cell of the terminal device are not at the same site, the transmission paths of the two carriers are different, and the distances between the terminal device and the network equipment of site 1 and the network equipment of site 2 are different, the first TA value and the second TA value are independent. Therefore, it is necessary to independently indicate and / or adjust the first TA value and the second TA value. The terminal device can adjust the first TA value and the second TA value respectively through two signalings sent by the network equipment of site 1 or the first cell, or adjust the first TA value and the second TA value respectively through different fields of a signaling sent by the network equipment of site 1 or the first cell.

[0620] Combine Figure 7 and Figure 8 The communication method, in one embodiment, as Figure 11 As shown, the first cell can be obtained by executing the method of steps 701 to 703 or the method of steps 801 to 806. When the terminal device switches from the second cell to the first cell, it can be determined that the terminal device continues to send uplink transmissions to the network device of site 2, that is, before and after the switching, the terminal device can send uplink transmissions to the same network device, that is, the network device of site 2, in the first cell and the second cell. Specifically:

[0621] Before the terminal device switches, the second cell is co-located with the network device of Site 2. When the terminal device sends information to the network device of Site 2 or the second cell in the second cell, it can send an uplink transmission including the information to the network device of Site 2 or the second cell, and the network device of Site 2 can send a downlink transmission to the terminal device.

[0622] After the terminal device is switched, the network equipment of the first cell and the network equipment of site 2 are at different sites. The information that the first cell and the network equipment of site 2 are at different sites can be notified to the terminal device by the network equipment of site 2 through an RRC message, a PDCCH message, or a system message. For example, the system message can be an on-demand system message. Since the terminal device continues to send uplink transmissions to the network equipment of site 2 in the first cell, when the terminal device sends information to the network equipment of site 1 or the first cell in the first cell, it can first send an uplink transmission including the information to the network equipment of site 2 in the first cell, and then the network equipment of site 2 sends the information to the network equipment of site 1 or the first cell through the backhaul, and the network equipment of site 1 can send a downlink transmission to the terminal device.

[0623] In one implementation, when the network device at site 2 determines that the first TA value needs to be adjusted, the first TA value is used to continue sending uplink transmissions to the network device at site 2. The adjustment amount for the first TA value may be sent to the network device at site 1 via the backhaul, and the network device at site 1 may send signaling to the terminal device to notify the terminal device to adjust the first TA value. The terminal device may assist the network device at site 2 in adjusting the first TA value by sending periodic signals to the network device at site 2.

[0624] Combine Figure 4 and Figure 6 In one embodiment, see the communication method Figure 12 , Figure 12 This is another switching scenario diagram provided by the embodiment of the present application. Figure 12As shown, this scenario includes cells at site 1 and site 2. The cell at site 1 has a NUL carrier and a DL carrier corresponding to the NUL carrier; the cell at site 2 has a NUL carrier, a DL carrier corresponding to the NUL carrier, and a SUL carrier. The SUL carrier covers part or all of the cells at site 1, meaning that part or all of the cells at site 1 and the cells at site 2 have the SUL carrier.

[0625] The terminal device switches from the cell of site 1 to the cell of site 2.

[0626] The cell at site 2 may be the first cell, and the cell at site 1 having the SUL carrier may be the second cell. The first cell may be obtained by executing steps 401 to 403 or steps 601 to 606. The network device at site 1 may be the second network device mentioned in the above method embodiment, and the network device at site 2 may be the first network device mentioned in the above method embodiment.

[0627] When the terminal device switches from the second cell to the first cell, it can be determined that the SUL carrier of the terminal device in the first cell is the SUL carrier of the terminal device in the second cell. That is, before and after the switch, the SUL carriers of the terminal device in the first cell and the second cell can be carriers of the same frequency band, and the uplink transmissions sent by the terminal device in the SUL carriers of the first cell and the second cell are received by the same network device. The terminal device can send uplink transmissions to the network device of site 2 on the SUL carrier. Specifically:

[0628] Before the terminal device switches, the SUL carrier of the second cell and the second cell are at different sites. When the terminal device sends information to the network device of site 1 or the second cell on the SUL carrier of the second cell, the terminal device may first send an uplink transmission including the information to the network device of site 2 on the SUL carrier of the second cell. Then, the network device of site 2 may send the information to the network device of site 1 or the second cell. For example, the network device of site 2 may send the information to the network device of site 1 or the second cell via a backhaul, and the network device of site 1 may send a downlink transmission to the terminal device.

[0629] After the terminal device is switched, the SUL carrier in the first cell and the first cell are co-located. The information that the SUL carrier in the first cell and the first cell are co-located can be notified to the terminal device by the network device of site 1 through an RRC message or a PDCCH message or a system message. For example, the system message can be an on-demand system message. Since the terminal device determines that the SUL carrier in the first cell is the SUL carrier of the terminal device in the second cell, when the terminal device sends information to the network device of site 2 or the first cell on the SUL carrier of the first cell, it can send an uplink transmission including the information to the network device of site 2 or the first cell, and the network device of site 2 can send a downlink transmission to the terminal device.

[0630] In one embodiment, when the network device at site 2 determines that the first TA value needs to be adjusted, the first TA value may be the TA value of the SUL carrier of the terminal device in the first cell. The network device at site 2 may send signaling to the terminal device to notify the terminal device to adjust the first TA value. The terminal device may assist the network device at site 2 in adjusting the first TA value by sending periodic signals to the network device at site 2.

[0631] In one embodiment, when the network device at site 2 determines that the second TA value needs to be adjusted, the second TA value may be the TA value of the NUL carrier of the terminal device in the first cell. The network device at site 2 may send signaling to the terminal device to notify the terminal device to adjust the second TA value. The terminal device may assist the network device at site 2 in adjusting the second TA value by sending periodic signals to the network device at site 2.

[0632] Because the SUL carrier of the first cell and the first cell are co-located, the NUL carrier of the first cell and the SUL carrier of the first cell of the terminal device are at the same site, and the transmission paths of these two carriers are the same, the first TA value and the second TA value can be the same. Therefore, there is no need to independently indicate and / or adjust the first TA value and the second TA value. The terminal device can adjust the first TA value and the second TA value through a signaling sent by the network equipment of Site 2 or the first cell.

[0633] Combine Figure 7 and Figure 8 The communication method, in one embodiment, as Figure 12 As shown, the first cell can be obtained by executing the method of steps 701 to 703 or the method of steps 801 to 806. When the terminal device switches from the second cell to the first cell, it can be determined that the terminal device continues to send uplink transmissions to the network device of site 2, that is, before and after the switching, the terminal device can send uplink transmissions to the same network device, that is, the network device of site 2, in the first cell and the second cell. Specifically:

[0634] Before the terminal device is switched, the second cell and the network equipment of site 2 are at different sites. When the terminal device sends information to the network equipment of site 1 or the second cell in the second cell, the second cell may first send an uplink transmission including the information to the network equipment of site 2. Then, the network equipment of site 2 may send the information to the network equipment of site 1 or the second cell. For example, the network equipment of site 2 may send the information to the network equipment of site 1 or the second cell via a backhaul, and the network equipment of site 1 may send a downlink transmission to the terminal device.

[0635] After the terminal device is switched, the first cell and the network device of site 2 are co-located. The information that the first cell and the network device of site 2 are co-located can be notified to the terminal device by the network device of site 1 through an RRC message, a PDCCH message, or a system message. For example, the system message can be an on-demand system message. Since the terminal device continues to send uplink transmissions to the network device of site 2 in the first cell, when the terminal device sends information to the network device of site 2 or the first cell in the first cell, it can send an uplink transmission including the information to the network device of site 2 or the first cell, and the network device of site 2 can send a downlink transmission to the terminal device.

[0636] In one embodiment, when the network device at site 2 determines that the first TA value needs to be adjusted, the first TA value is used to continue sending uplink transmissions to the network device at site 2. The network device at site 2 may send signaling to the terminal device to notify the terminal device to adjust the first TA value. The terminal device may assist the network device at site 2 in adjusting the first TA value by sending periodic signals to the network device at site 2.

[0637] In one embodiment, see Figure 13 , Figure 13 This is another switching scenario diagram provided by the embodiment of the present application. Figure 13 As shown, this scenario includes cells at site 1, site 2, and site 3. The cell at site 1 has a NUL carrier and a DL carrier corresponding to the NUL carrier; the cell at site 2 has a NUL carrier, a DL carrier corresponding to the NUL carrier, and a SUL carrier; and the cell at site 3 has a NUL carrier and a DL carrier corresponding to the NUL carrier. The SUL carrier covers some or all of the cells at site 1 and some or all of the cells at site 3. That is, some or all of the cells at site 1 and some or all of the cells at site 3 have the SUL carrier.

[0638] When the terminal device communicates in the cell of site 1, if switching is required, when the downlink quality of the cells of site 2 and site 3 is equal or not much different, the cell of site 2 can be preferentially selected as the first cell, so that after switching, the SUL carrier and the first cell share the same site.

[0639] The terminal device can switch from the cell of site 1 to the cell of site 2, combined with Figure 4 、 Figure 6 、 Figure 7 and Figure 8 For communication methods and specific embodiments, please refer to the above Figure 12 The detailed description is omitted here.

[0640] Combine Figure 4 and Figure 6 In one embodiment, see the communication method Figure 14 , Figure 14 This is another switching scenario diagram provided by the embodiment of the present application. Figure 14 As shown, this scenario includes cells at site 1, site 2, and site 3. The cell at site 1 has a NUL carrier and a DL carrier corresponding to the NUL carrier; the cell at site 2 has a NUL carrier, a DL carrier corresponding to the NUL carrier, and a SUL carrier; and the cell at site 3 has a NUL carrier and a DL carrier corresponding to the NUL carrier. The SUL carrier covers some or all of the cells at site 1 and some or all of the cells at site 3. That is, some or all of the cells at site 1 and some or all of the cells at site 3 have the SUL carrier.

[0641] The terminal device switches from the cell of site 1 to the cell of site 3.

[0642] The cell having the SUL carrier at site 3 may be a first cell, and the cell having the SUL carrier at site 1 may be a second cell. The first cell may be obtained by executing steps 401 to 403 or steps 601 to 606. The network device at site 1 may be the second network device mentioned in the above method embodiment, and the network device at site 3 may be the first network device mentioned in the above method embodiment.

[0643] When the terminal device switches from the second cell to the first cell, it can be determined that the SUL carrier of the terminal device in the first cell is the SUL carrier of the terminal device in the second cell. That is, before and after the switch, the SUL carriers of the terminal device in the first cell and the second cell can be carriers of the same frequency band, and the uplink transmissions sent by the terminal device in the SUL carriers of the first cell and the second cell are received by the same network device. The terminal device can send uplink transmissions to the network device of site 2 on the SUL carrier. Specifically:

[0644] Before the terminal device switches, the SUL carrier of the second cell and the second cell are at different sites. When the terminal device sends information to the network device of site 1 or the second cell on the SUL carrier of the second cell, the terminal device may first send an uplink transmission including the information to the network device of site 2 on the SUL carrier of the second cell. Then, the network device of site 2 may send the information to the network device of site 1 or the second cell. For example, the network device of site 2 may send the information to the network device of site 1 or the second cell via a backhaul, and the network device of site 1 may send a downlink transmission to the terminal device.

[0645] After the terminal device switches, the SUL carrier in the first cell and the first cell are at different sites. The information that the SUL carrier in the first cell and the first cell are at different sites can be notified to the terminal device by the network device of site 1 through an RRC message or a PDCCH message or a system message. For example, the system message can be an on-demand system message. Since the terminal device determines that the SUL carrier in the first cell is the SUL carrier of the terminal device in the second cell, when the terminal device sends information to the network device of site 3 or the first cell on the SUL carrier of the first cell, it can first send an uplink transmission including the information to the network device of site 2 on the SUL carrier of the first cell, and then the network device of site 2 sends the information to the network device of site 3 or the first cell. For example, the network device of site 2 can send the information to the network device of site 3 or the first cell through the backhaul, and the network device of site 3 can send a downlink transmission to the terminal device.

[0646] In one embodiment, when the network device at site 2 determines that the first TA value needs to be adjusted, the first TA value may be the TA value of the SUL carrier of the terminal device in the first cell. The adjustment amount of the first TA value may be sent to the network device at site 3 via the backhaul, and the network device at site 3 may send signaling to the terminal device to notify the terminal device to adjust the first TA value. The terminal device may assist the network device at site 2 in adjusting the first TA value by sending periodic signals to the network device at site 2.

[0647] In one embodiment, when the network device at site 3 determines that the second TA value needs to be adjusted, the second TA value may be the TA value of the NUL carrier of the terminal device in the first cell. The network device at site 3 may send signaling to the terminal device to notify the terminal device to adjust the second TA value. The terminal device may assist the network device at site 3 in adjusting the second TA value by sending periodic signals to the network device at site 3.

[0648] Since the SUL carrier in the first cell and the first cell are at different sites, the NUL carrier in the first cell and the SUL carrier in the first cell of the terminal device are not at the same site, the transmission paths of the two carriers are different, and the distance between the terminal device and the network equipment of site 3 and the network equipment of site 2 is different, the first TA value and the second TA value are independent. Therefore, it is necessary to independently indicate and / or adjust the first TA value and the second TA value. The terminal device can adjust the first TA value and the second TA value respectively through two signalings sent by the network equipment of site 3 or the first cell, or adjust the first TA value and the second TA value respectively through different fields of a signaling sent by the network equipment of site 3 or the first cell.

[0649] Combine Figure 7 and Figure 8 The communication method, in one embodiment, as Figure 14 As shown, the first cell can be obtained by executing the method of steps 701 to 703 or the method of steps 801 to 806. When the terminal device switches from the second cell to the first cell, it can be determined that the terminal device continues to send uplink transmissions to the network device of site 2, that is, before and after the switching, the terminal device can send uplink transmissions to the same network device, that is, the network device of site 2, in the first cell and the second cell. Specifically:

[0650] Before the terminal device is switched, the second cell and the network equipment of site 2 are at different sites. When the terminal device sends information to the network equipment of site 1 or the second cell in the second cell, the second cell may first send an uplink transmission including the information to the network equipment of site 2. Then, the network equipment of site 2 may send the information to the network equipment of site 1 or the second cell. For example, the network equipment of site 2 may send the information to the network equipment of site 1 or the second cell via a backhaul, and the network equipment of site 1 may send a downlink transmission to the terminal device.

[0651] After the terminal device is switched, the network equipment of the first cell and the network equipment of site 2 are at different sites. The information that the network equipment of site 2 and the first cell are at different sites can be notified to the terminal device by the network equipment of site 1 through an RRC message, a PDCCH message, or a system message. For example, the system message can be an on-demand system message. Since the terminal device continues to send uplink transmissions to the network equipment of site 2 in the first cell, when the terminal device sends information to the network equipment of site 3 or the first cell in the first cell, it can first send an uplink transmission including the information to the network equipment of site 2 in the first cell, and then the network equipment of site 2 sends the information to the network equipment of site 3 or the first cell through the backhaul, and the network equipment of site 3 can send a downlink transmission to the terminal device.

[0652] In one implementation, when the network device at site 2 determines that the first TA value needs to be adjusted, the first TA value is used to continue sending uplink transmissions to the network device at site 2. The adjustment amount for the first TA value may be sent to the network device at site 3 via the backhaul, and the network device at site 3 may send signaling to the terminal device to notify the terminal device to adjust the first TA value. The terminal device may assist the network device at site 2 in adjusting the first TA value by sending periodic signals to the network device at site 2.

[0653] Combine Figure 4 and Figure 6 In one embodiment, the communication method is Figure 15 , Figure 15 This is another switching scenario diagram provided by the embodiment of the present application. Figure 15 As shown, the scenario includes a site, a cell 1 in the site, and a cell 2 in the site, wherein the site has a NUL carrier, a DL carrier corresponding to the NUL carrier, and a SUL carrier.

[0654] It should be understood that in the embodiments of the present application, a network device may correspond to one or more cells. The second cell and the first cell may belong to the same network device, that is, the first network device and the second network device may be the same network device. In this case, the terminal device performs a handover within the network device.

[0655] The terminal device switches from cell 1 to cell 2, and cells 1 and 2 belong to the same site.

[0656] Cell 1 may be the second cell, cell 2 may be the first cell, and cells 1 and 2 correspond to the same network device. The first cell may be obtained by executing the method of steps 401 to 403 or the method of steps 601 to 606.

[0657] When the terminal device switches from the second cell to the first cell, it can be determined that the SUL carrier of the terminal device in the first cell is the SUL carrier of the terminal device in the second cell, that is, before and after the switch, the SUL carriers of the terminal device in the first cell and the second cell can be carriers of the same frequency band, and the uplink transmissions sent by the terminal device in the SUL carriers of the first cell and the second cell are received by the same network device. The terminal device can send uplink transmissions to the network device of the site on the SUL carrier. Specifically:

[0658] Before the terminal device switches, the SUL carrier of the second cell is co-located with the second cell. When the terminal device sends information to the network equipment of the site or the second cell via the SUL carrier of the second cell, the terminal device may send an uplink transmission including the information to the network equipment of the site or the second cell, and the network equipment of the site may send a downlink transmission to the terminal device.

[0659] After the terminal device is switched, the SUL carrier in the first cell and the first cell are co-located. The information that the SUL carrier in the first cell and the first cell are co-located can be notified to the terminal device by the network device of the site through an RRC message or a PDCCH message or a system message. For example, the system message can be an on-demand system message. Since the terminal device determines that the SUL carrier in the first cell is the SUL carrier of the terminal device in the second cell, when the terminal device sends information to the network device of the site or the first cell on the SUL carrier of the first cell, it can send an uplink transmission including the information to the network device of the site or the first cell, and the network device of the site can send a downlink transmission to the terminal device.

[0660] In one embodiment, when the network device at the site determines that the first TA value needs to be adjusted, the first TA value may be the TA value of the SUL carrier of the terminal device in the first cell. The network device at the site may send signaling to the terminal device to notify the terminal device to adjust the first TA value. The terminal device may assist the network device at the site in adjusting the first TA value by sending periodic signals to the network device at the site.

[0661] In one embodiment, when the network device of the site determines that the second TA value needs to be adjusted, the second TA value may be the TA value of the NUL carrier of the terminal device in the first cell. The network device of the site may send signaling to the terminal device to notify the terminal device to adjust the second TA value. The terminal device may assist the network device of the site in adjusting the second TA value by sending periodic signals to the network device of the site.

[0662] Because the SUL carrier of the first cell and the first cell are co-located, the NUL carrier of the first cell and the SUL carrier of the first cell of the terminal device are at the same site, and the transmission paths of these two carriers are the same, the first TA value and the second TA value can be the same. Therefore, there is no need to independently indicate and / or adjust the first TA value and the second TA value. The terminal device can adjust the first TA value and the second TA value through a signaling sent by the network equipment of the site or the first cell.

[0663] Combine Figure 7 and Figure 8 The communication method, in one embodiment, as Figure 15 As shown, the first cell can be obtained by executing the method of steps 701 to 703 or the method of steps 801 to 806. When the terminal device switches from the second cell to the first cell, it can be determined that the terminal device continues to send uplink transmissions to the network device of the site, that is, before and after the switching, the terminal device can send uplink transmissions to the same network device, that is, the network device of the site, in the first cell and the second cell. Specifically:

[0664] Before the terminal device switches, the second cell and the network equipment of the site are co-located. When the terminal device sends information to the network equipment of the site or the second cell in the second cell, it can send an uplink transmission including the information to the network equipment of the site or the second cell, and the network equipment of the site can send a downlink transmission to the terminal device.

[0665] After the terminal device is switched, the first cell and the network equipment of the site are co-located. The information that the first cell and the network equipment of the site are co-located can be notified to the terminal device by the network equipment of the site through an RRC message, a PDCCH message, or a system message. For example, the system message can be an on-demand system message. Since the terminal device continues to send uplink transmissions to the network equipment of the site in the first cell, when the terminal device sends information to the network equipment of the site or the first cell, it can send an uplink transmission including the information to the network equipment of the site or the first cell, and the network equipment of the site can send a downlink transmission to the terminal device.

[0666] In one embodiment, when the network device at the site determines that the first TA value needs to be adjusted, the first TA value is used to continue sending uplink transmissions to the network device at the site. The network device at the site may send signaling to the terminal device to notify the terminal device to adjust the first TA value. The terminal device may assist the network device at the site in adjusting the first TA value by sending periodic signals to the network device at the site.

[0667] Based on the above network architecture, please refer to Figure 16 , Figure 16 1 is a schematic diagram of the structure of a communication device provided in an embodiment of the present application. The communication device may be a terminal device or a module (eg, a chip) in the terminal device. Figure 16 As shown, the communication device 1600 includes at least: a processing unit 1601 and a transceiver unit 1602; wherein:

[0668] Processing unit 1601 is used to determine that after the terminal device switches from the second cell to the first cell, the carrier for uplink transmission of the terminal device in the first cell is the first carrier; wherein the first carrier and the second carrier belong to the same frequency band, and the second carrier is the carrier of the terminal device in the second cell.

[0669] In one embodiment, the processing unit 1601 is also used to determine a first TA value based on the transmission timing of the terminal device on the second carrier, the downlink timing of the first cell and the TA offset value of the first cell, where the first TA value is the TA value of the terminal device on the first carrier.

[0670] In one embodiment, the same carrier as the second carrier exists in valid carriers of the first cell.

[0671] In one embodiment, when the carrier of the terminal device in the second cell is the third carrier and there is no carrier identical to the third carrier among the valid carriers of the first cell, the terminal device switches to the second carrier in the second cell.

[0672] In one embodiment, the communication device further comprises:

[0673] The transceiver unit 1602 is used to receive first indication information sent by the second network device, where the first indication information is used to indicate that the carrier for uplink transmission by the terminal device in the first cell is the first carrier, and the second network device is the network device corresponding to the second cell.

[0674] In one embodiment, the transceiver unit 1602 is further configured to receive first information sent by a second network device, where the first information includes a TA offset value of the first cell.

[0675] In one embodiment, the first information further includes: at least one of a time slot offset value between the first cell and the second cell, a system frame number offset value between the first cell and the second cell, and a frame boundary offset value between the first cell and the second cell;

[0676] The processing unit 1601 determines the first TA value according to the transmission timing of the terminal device on the second carrier, the downlink timing of the first cell and the TA offset value of the first cell, including: determining the first TA value according to the transmission timing of the terminal device on the second carrier, the downlink timing of the first cell and the first information.

[0677] In one embodiment, the first TA value may satisfy the following formula:

[0678] or

[0679] or

[0680] or

[0681] or

[0682]

[0683] Among them, N TA is the first TA value, T tt is the transmission timing of the terminal device on the second carrier, T is the downlink timing of the first cell, N TA-offset is the TA offset value of the first cell, TC =1 / (Δf max ·N f ), Δf max =480·10 3 Hz and N f =4096, T slot-offset is the time slot offset between the first cell and the second cell, T sfn-offset is the system frame number offset between the first cell and the second cell, the T Fb-offset is the frame boundary offset value between the first cell and the second cell.

[0684] In one embodiment, the transceiver unit 1602 is further configured to receive second indication information sent by the second network device, where the second indication information is used to indicate the first cell, and the second indication information includes an ID of the first cell.

[0685] In one embodiment, the transceiver unit 1602 is further configured to receive a measurement configuration sent by the second network device; report a measurement result of the fifth cell to the second network device according to the measurement configuration; and the third cell is at least one of the fifth cells.

[0686] In one embodiment, the processing unit 1601 is further configured to determine N fourth cells based on the measurement result of the third cell and the information of the third cell, where N is an integer greater than or equal to 1, and the valid carrier of the third cell and the valid carrier of the second cell have at least one identical carrier;

[0687] The transceiver unit 1602 is also used to send indication information of the N fourth cells to the second network device; receive second indication information sent by the second network device, the second indication information is used to indicate the first cell, the second indication information includes the ID of the first cell, and the first cell is one of the N fourth cells.

[0688] In one embodiment, the processing unit 1601 determines N fourth cells based on the measurement results of the third cell and the information of the third cell, including: determining the priority corresponding to each cell in the third cell based on the information of the third cell; and determining the N fourth cells based on the priority corresponding to each cell in the third cell and the measurement results of the third cell.

[0689] In one embodiment, the transceiver unit 1602 is further configured to receive a measurement configuration sent by the second network device;

[0690] The processing unit 1601 is further configured to determine a measurement result of the fifth cell according to the measurement configuration.

[0691] In one embodiment, the transceiver unit 1602 is further configured to receive information about the third cell sent by the second network device, where the third cell is at least one of the fifth cells.

[0692] In one embodiment, the transceiver unit 1602 is further configured to send second information on the first carrier, where the second information is used to confirm the handover to the first network device, where the first network device is a network device corresponding to the first cell.

[0693] In one embodiment, the transceiver unit 1602 is also used to receive third indication information sent by the second network device, where the third indication information is used to indicate whether the second TA value is the same as the first TA value, and the second TA value is the TA value of the terminal device in the fourth carrier, and the fourth carrier is a carrier of the terminal device in the first cell that is different from the first carrier.

[0694] In one embodiment, the transceiver unit 1602 is further configured to send second information on the fourth carrier, where the second information is used to confirm the handover to the first network device.

[0695] It can be understood that the processing unit 1601 in the embodiment of the present application can be implemented by a processor or a processor-related circuit component, and the transceiver unit 1602 can be implemented by a transceiver or a transceiver-related circuit component.

[0696] Based on the above network architecture, please refer to Figure 17 , Figure 17 This is a schematic diagram of the structure of another communication device provided in an embodiment of the present application. Figure 17 As shown, the communication device 1700 may include a processor 1701, a memory 1702, a transceiver 1703 and a bus 1704. The memory 1702 may exist independently and may be connected to the processor 1701 via the bus 1704. The memory 1702 may also be integrated with the processor 1701. The memory 1702 stores instructions or program codes and may also store data. The processor 1701 is used to execute the instructions or program codes stored in the memory 1702. The bus 1704 is used to realize the connection between these components. Figure 17 The bus is represented by a thick line, and the connection between other components is only for schematic illustration and is not intended to be limiting. The bus 1704 can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 17 Only one thick line is used in the diagram, but this does not mean that there is only one bus or one type of bus.

[0697] When the instructions or program codes stored in the memory 1702 are executed, the processor 1701 is used to execute the operations executed by the processing unit 1601 in the above embodiment, and the transceiver 1703 is used to execute the operations executed by the transceiver unit 1602 in the above embodiment.

[0698] It should be noted that the communication device 1600 or the communication device 1700 of the embodiment of the present application may correspond to the terminal device in the method embodiment provided in the present application, and the operations and / or functions of each module in the communication device 1600 or the communication device 1700 may be respectively implemented. Figure 4 and Figure 6 For the sake of brevity, the corresponding processes of each method in are not repeated here.

[0699] Based on the above network architecture, please refer to Figure 18 , Figure 18 1 is a structural diagram of another communication device provided in an embodiment of the present application. The communication device may be a second network device, or a module (eg, a chip) in the second network device. Figure 18 As shown, the communication device 1800 includes at least: a transceiver unit 1801 and a processing unit 1802; wherein:

[0700] The transceiver unit 1801 is used to send first indication information to the terminal device, where the first indication information is used to indicate that the carrier used by the terminal device for uplink transmission in the first cell is the first carrier, wherein the first carrier and the second carrier belong to the same frequency band, and the second carrier is the carrier of the second cell.

[0701] In one embodiment, the transceiver unit 1801 is further used to send first information to the terminal device, where the first information includes a TA offset value of the first cell.

[0702] In one embodiment, the first information further includes: at least one of a time slot offset value between the first cell and the second cell, a system frame number offset value between the first cell and the second cell, and a frame boundary offset value between the first cell and the second cell.

[0703] In one embodiment, the communication device further comprises:

[0704] The processing unit 1802 is configured to determine, based on the measurement result of the third cell and the information of the third cell, the first cell, where an effective carrier of the third cell and an effective carrier of the second cell have at least one identical carrier;

[0705] The transceiver unit 1801 is further used to send second indication information to the terminal device, where the second indication information is used to indicate the first cell, and the second indication information includes the ID of the first cell.

[0706] In one embodiment, the processing unit 1802 determines the first cell based on the measurement results of the third cell and the information of the third cell, including: determining the priority corresponding to each cell in the third cell based on the information of the third cell; determining the first cell based on the priority corresponding to each cell in the third cell and the measurement results of the third cell.

[0707] In one embodiment, the transceiver unit 1801 is further configured to send a measurement configuration to the terminal device;

[0708] In one embodiment, the transceiver unit 1801 is further configured to receive a measurement result of a fifth cell sent by the terminal device; the third cell is at least one cell in the fifth cell.

[0709] In one embodiment, the transceiver unit 1801 is further configured to receive indication information of N fourth cells sent by the terminal device, where N is an integer greater than or equal to 1, and the N fourth cells are determined by the terminal device based on the measurement result of the third cell and the information of the third cell, and the effective carrier of the third cell and the effective carrier of the second cell have at least one identical carrier;

[0710] The processing unit 1802 is further configured to determine the first cell according to the N fourth cells, where the first cell is one of the N fourth cells;

[0711] The transceiver unit 1801 is further used to send second indication information to the terminal device, where the second indication information is used to indicate the first cell, and the second indication information includes the ID of the first cell.

[0712] In one embodiment, the transceiver unit 1801 is further configured to send a measurement configuration to a terminal device.

[0713] In one embodiment, the transceiver unit 1801 is further configured to send information of the third cell to the terminal device, where the third cell is at least one of the fifth cells.

[0714] In one embodiment, the transceiver unit 1801 is also used to send third indication information to the terminal device, where the third indication information is used to indicate whether the second TA value is the same as the first TA value, and the second TA value is the TA value of the terminal device in the fourth carrier, and the fourth carrier is a carrier of the terminal device in the first cell that is different from the first carrier.

[0715] In one embodiment, the transceiver unit 1801 is further used to send a request message to a first network device, where the request message is used to request the terminal device to access the first network device, and the first network device is a network device corresponding to the first cell.

[0716] It can be understood that the transceiver unit 1801 in the embodiment of the present application can be implemented by a transceiver or a transceiver-related circuit component, and the processing unit 1802 can be implemented by a processor or a processor-related circuit component.

[0717] Based on the above network architecture, please refer to Figure 19 , Figure 19 This is a schematic diagram of the structure of another communication device provided in an embodiment of the present application. Figure 19 As shown, the communication device 1900 may include a processor 1901, a memory 1902, a transceiver 1903 and a bus 1904. The memory 1902 may exist independently and may be connected to the processor 1901 via the bus 1904. The memory 1902 may also be integrated with the processor 1901. The memory 1902 stores instructions or program codes and may also store data. The processor 1901 is used to execute the instructions or program codes stored in the memory 1902. The bus 1904 is used to realize the connection between these components. Figure 19 The bus is represented by a thick line, and the connection between other components is only for schematic illustration and is not intended to be limiting. The bus 1904 can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 19 Only one thick line is used in the diagram, but this does not mean that there is only one bus or one type of bus.

[0718] When the instructions or program codes stored in the memory 1902 are executed, the processor 1901 is used to execute the operations executed by the processing unit 1802 in the above embodiment, and the transceiver 1903 is used to execute the operations executed by the transceiver unit 1801 in the above embodiment.

[0719] It should be noted that the communication device 1800 or the communication device 1900 of the embodiment of the present application may correspond to the terminal device in the method embodiment provided in the present application, and the operations and / or functions of each module in the communication device 1800 or the communication device 1900 may be respectively implemented. Figure 4 and Figure 6 For the sake of brevity, the corresponding processes of each method in are not repeated here.

[0720] Based on the above network architecture, please refer to Figure 20 , Figure 201 is a structural diagram of another communication device provided in an embodiment of the present application. The communication device may be a first network device, or a module (eg, a chip) in the first network device. Figure 20 As shown, the communication device 2000 at least includes: a transceiver unit 2001; wherein:

[0721] The transceiver unit 2001 is used to receive request information sent by the second network device, where the request information is used to request the terminal device to access the first network device, and the second network device is the network device corresponding to the second cell.

[0722] It can be understood that the transceiver unit 2001 in the embodiment of the present application can be implemented by a transceiver or transceiver-related circuit components.

[0723] Based on the above network architecture, please refer to Figure 21 , Figure 21 This is a schematic diagram of the structure of another communication device provided in an embodiment of the present application. Figure 21 As shown, the communication device 2100 may include a processor 2101, a memory 2102, a transceiver 2103 and a bus 2104. The memory 2102 may exist independently and may be connected to the processor 2101 via the bus 2104. The memory 2102 may also be integrated with the processor 2101. The memory 2102 stores instructions or program codes and may also store data. The processor 2101 is used to execute the instructions or program codes stored in the memory 2102. The bus 2104 is used to realize the connection between these components. Figure 21 The bus is represented by a thick line, and the connection between other components is only for schematic illustration and is not intended to be limiting. The bus 2104 can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 21 Only one thick line is used in the diagram, but this does not mean that there is only one bus or one type of bus.

[0724] When the instructions or program codes stored in the memory 2102 are executed, the transceiver 2103 is used to perform the operations performed by the transceiver unit 2001 in the above embodiment.

[0725] It should be noted that the communication device 2000 or the communication device 2100 of the embodiment of the present application may correspond to the terminal device in the method embodiment provided in the present application, and the operations and / or functions of each module in the communication device 2000 or the communication device 2100 may be respectively implemented. Figure 6 For the sake of brevity, the corresponding processes of each method in are not repeated here.

[0726] Based on the above network architecture, please refer to Figure 22 , Figure 221 is a structural diagram of another communication device provided in an embodiment of the present application. The communication device may be a terminal device or a module (eg, a chip) in the terminal device. Figure 22 As shown, the communication device 2200 includes at least: a transceiver unit 2201 and a processing unit 2202; wherein:

[0727] The transceiver unit 2201 is used to receive third information sent by the second network device, where the third information includes first indication information and the ID of the first cell, and the first indication information is used to instruct the terminal device to continue sending uplink transmission to the fourth network device.

[0728] In one embodiment, the communication device may also include: a processing unit 2202, used to determine a first TA value based on the first sending timing, the downlink timing of the first cell and the TA offset value of the first cell, and the first TA value is used to continue sending uplink transmission to the fourth network device.

[0729] In one embodiment, the transceiver unit 2201 is further configured to receive first information sent by a second network device, where the first information includes a TA offset value of the first cell.

[0730] In one embodiment, the first information further includes: at least one of a time slot offset value between the first cell and the second cell, a system frame number offset value between the first cell and the second cell, and a frame boundary offset value between the first cell and the second cell.

[0731] In one embodiment, the processing unit 2202 determines the first TA value based on the first transmission timing, the downlink timing of the first cell and the TA offset value of the first cell, including: determining the first TA value based on the first transmission timing, the downlink timing of the first cell and the first information.

[0732] In one embodiment, the first TA value may satisfy the following formula:

[0733] or

[0734] or

[0735] or

[0736] or

[0737]

[0738] Among them, N TA is the first TA value, T ttis the first transmission timing, T is the downlink timing of the first cell, N TA-offset is the TA offset value of the first cell, T C =1 / (Δf max ·N f ), Δf max =480·10 3 Hz and N f =4096, T slot-offset is the time slot offset between the first cell and the second cell, T sfn-offset is the system frame number offset between the first cell and the second cell, the T Fb-offset is the frame boundary offset value between the first cell and the second cell.

[0739] In one embodiment, the transceiver unit 2201 is further used to receive second indication information sent by the second network device, where the second indication information is used to indicate the first cell, and the second indication information includes an ID of the first cell.

[0740] In one embodiment, the transceiver unit 2201 is further configured to receive a measurement configuration sent by the second network device; report a measurement result of the fifth cell to the second network device according to the measurement configuration; and the third cell is at least one of the fifth cells.

[0741] In one embodiment, the processing unit 2202 is further configured to determine N fourth cells based on the measurement result of the third cell and the information of the third cell, where N is an integer greater than or equal to 1, and the valid carrier of the third cell and the valid carrier of the second cell have at least one identical carrier;

[0742] The transceiver unit 2201 is also used to send indication information of the N fourth cells to the second network device; receive second indication information sent by the second network device, the second indication information is used to indicate the first cell, the second indication information includes the ID of the first cell, and the first cell is one of the N fourth cells.

[0743] In one embodiment, the processing unit 2202 determines N fourth cells based on the measurement results of the third cell and the information of the third cell, including: determining the priority corresponding to each cell in the third cell based on the information of the third cell; and determining the N fourth cells based on the priority corresponding to each cell in the third cell and the measurement results of the third cell.

[0744] In one embodiment, the transceiver unit 2201 is further configured to receive a measurement configuration sent by the second network device; and determine a measurement result of the fifth cell according to the measurement configuration.

[0745] In one embodiment, the transceiver unit 2201 is further configured to receive information about the third cell sent by the second network device, where the third cell is at least one of the fifth cells.

[0746] In one embodiment, the transceiver unit 2201 is further used to send uplink transmission information to the first network device when the fourth network device is the first network device, the uplink transmission information includes second information, and the second information is used to confirm the switching to the first network device; or to send uplink transmission information to the second network device when the fourth network device is the second network device, the uplink transmission information includes second information, and the second information is used to confirm the switching to the first network device.

[0747] It can be understood that the transceiver unit 2201 in the embodiment of the present application can be implemented by a transceiver or a transceiver-related circuit component, and the processing unit 2202 can be implemented by a processor or a processor-related circuit component.

[0748] Based on the above network architecture, please refer to Figure 23 , Figure 23 This is a structural diagram of another communication device provided in an embodiment of the present application. Figure 23 As shown, the communication device 2300 may include a processor 2301, a memory 2302, a transceiver 2303 and a bus 2304. The memory 2302 may exist independently and may be connected to the processor 2301 via the bus 2304. The memory 2302 may also be integrated with the processor 2301. The memory 2302 stores instructions or program codes and may also store data. The processor 2301 is used to execute the instructions or program codes stored in the memory 2302. The bus 2304 is used to realize the connection between these components. Figure 23 The bus is represented by a thick line, and the connection between other components is only for schematic illustration and is not intended to be limiting. The bus 2304 can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 23 Only one thick line is used in the diagram, but this does not mean that there is only one bus or one type of bus.

[0749] When the instructions or program codes stored in the memory 2302 are executed, the processor 2301 is used to execute the operations executed by the processing unit 2202 in the above embodiment, and the transceiver 2303 is used to execute the operations executed by the transceiver unit 2201 in the above embodiment.

[0750] It should be noted that the communication device 2200 or the communication device 2300 of the embodiment of the present application may correspond to the terminal device in the method embodiment provided in the present application, and the operations and / or functions of each module in the communication device 2200 or the communication device 2300 may be respectively implemented. Figure 7 and Figure 8 For the sake of brevity, the corresponding processes of each method in are not repeated here.

[0751] Based on the above network architecture, please refer to Figure 24 , Figure 24 1 is a structural diagram of another communication device provided in an embodiment of the present application. The communication device may be a second network device, or a module (eg, a chip) in the second network device. Figure 24 As shown, the communication device 2400 includes at least: a transceiver unit 2401 and a processing unit 2402; wherein:

[0752] The transceiver unit 2401 is used to send third information to the terminal device, where the third information includes first indication information and the ID of the first cell, and the first indication information is used to instruct the terminal device to continue sending uplink transmission to the fourth network device.

[0753] In one embodiment, the transceiver unit 2401 is further used to send first information to the terminal device, where the first information includes a TA offset value of the first cell.

[0754] In one embodiment, the first information further includes: at least one of a time slot offset value between the first cell and the second cell, a system frame number offset value between the first cell and the second cell, and a frame boundary offset value between the first cell and the second cell.

[0755] In one embodiment, the communication device may further include: a processing unit 2402, configured to determine the first cell based on the...

Claims

1. A communication method, characterized in that: include: Determining that after the terminal device switches from the second cell to the first cell, a carrier for uplink transmission by the terminal device in the first cell is the first carrier; The first carrier and the second carrier belong to the same frequency band, and the second carrier is a carrier of the terminal device in the second cell; The method further comprises: A first TA value is determined based on the transmission timing of the terminal device on the second carrier, the downlink timing of the first cell and the timing advance TA offset value of the first cell, where the first TA value is the TA value of the terminal device on the first carrier.

2. The method according to claim 1, characterized in that The same carrier as the second carrier exists in valid carriers of the first cell.

3. The method according to claim 2, characterized in that The method further comprises: When the carrier of the terminal device in the second cell is the third carrier and there is no carrier identical to the third carrier among the valid carriers of the first cell, the terminal device switches to the second carrier in the second cell.

4. The method according to any one of claims 1 to 3, characterized in that: The method further comprises: Receive first indication information sent by the second network device, where the first indication information is used to indicate that the carrier for uplink transmission by the terminal device in the first cell is the first carrier, and the second network device is the network device corresponding to the second cell.

5. The method according to claim 4, characterized in that The method further comprises: First information sent by a second network device is received, where the first information includes a TA offset value of the first cell.

6. The method according to claim 5, characterized in that The first information further includes: at least one of a time slot offset value between the first cell and the second cell, a system frame number offset value between the first cell and the second cell, and a frame boundary offset value between the first cell and the second cell; The determining the first TA value according to the transmit timing of the terminal device on the second carrier, the downlink timing of the first cell, and the TA offset value of the first cell includes: A first TA value is determined based on the transmission timing of the terminal device on the second carrier, the downlink timing of the first cell and the first information.

7. The method according to claim 6, characterized in that The first TA value satisfies the following formula: or or or or Among them, N TA is the first TA value, T tt is the transmission timing of the terminal device on the second carrier, T is the downlink timing of the first cell, N TA-offset is the TA offset value of the first cell, T C =1 / (Δf max ·N f ), Δf max =480·10 3 Hz and N f =4096, T slot-offset is the time slot offset between the first cell and the second cell, T sfn-offset is the system frame number offset between the first cell and the second cell, the T Fb-offset is the frame boundary offset value between the first cell and the second cell.

8. The method according to claim 4, characterized in that The method further comprises: Receive second indication information sent by the second network device, where the second indication information is used to indicate the first cell, and the second indication information includes an identification ID of the first cell.

9. The method according to claim 4, characterized in that The method further comprises: Determine N fourth cells based on the measurement result of the third cell and the information of the third cell, where N is an integer greater than or equal to 1, and the valid carriers of the third cell and the valid carriers of the second cell have at least one identical carrier; Sending indication information of the N fourth cells to the second network device; Receive second indication information sent by the second network device, where the second indication information is used to indicate the first cell, and the second indication information includes an ID of the first cell, where the first cell is one of the N fourth cells.

10. The method according to claim 9, characterized in that The determining the N fourth cells according to the measurement result of the third cell and the information of the third cell includes: Determine the priority corresponding to each cell in the third cell according to the information of the third cell; The N fourth cells are determined according to the priority corresponding to each cell in the third cells and the measurement result of the third cell.

11. The method according to any one of claims 5 to 10, characterized in that: The method further comprises: Second information is sent on the first carrier, where the second information is used to confirm the handover to a first network device, where the first network device is a network device corresponding to the first cell.

12. A communication method, characterized in that: include: Sending first indication information to a terminal device, where the first indication information is used to indicate that a carrier for uplink transmission by the terminal device in the first cell is a first carrier, where the first carrier and the second carrier belong to the same frequency band, and the second carrier is a carrier of the terminal device in the second cell; The timing advance TA value of the terminal device on the first carrier is a first TA value, and the first TA value is determined based on the sending timing of the terminal device on the second carrier, the downlink timing of the first cell and the timing advance TA offset value of the first cell.

13. The method according to claim 12, characterized in that The method further comprises: Send first information to the terminal device, where the first information includes a TA offset value of the first cell.

14. The method according to claim 13, characterized in that The first information also includes: at least one of a time slot offset value between the first cell and the second cell, a system frame number offset value between the first cell and the second cell, and a frame boundary offset value between the first cell and the second cell.

15. The method according to claim 12, characterized in that The method further comprises: Determine the first cell according to a measurement result of a third cell and information about the third cell, where an effective carrier of the third cell and an effective carrier of the second cell have at least one identical carrier; Send second indication information to the terminal device, where the second indication information is used to indicate the first cell, and the second indication information includes an identification ID of the first cell.

16. The method according to claim 15, characterized in that The determining the first cell according to the measurement result of the third cell and the information of the third cell includes: Determine the priority corresponding to each cell in the third cell according to the information of the third cell; The first cell is determined according to the priority corresponding to each cell in the third cells and the measurement result of the third cells.

17. The method according to claim 15, characterized in that The method further comprises: receiving indication information of N fourth cells sent by the terminal device, where N is an integer greater than or equal to 1, the N fourth cells being determined by the terminal device based on the measurement result of the third cell and information of the third cell, and the effective carrier of the third cell and the effective carrier of the second cell having at least one identical carrier; Determine the first cell according to the N fourth cells, where the first cell is one of the N fourth cells; Send second indication information to the terminal device, where the second indication information is used to indicate the first cell, and the second indication information includes the ID of the first cell.

18. A communication device, characterized in that: include: a processing unit, configured to determine that, after the terminal device switches from the second cell to the first cell, a carrier for uplink transmission by the terminal device in the first cell is the first carrier; The first carrier and the second carrier belong to the same frequency band, and the second carrier is a carrier of the terminal device in the second cell; The processing unit is also used to determine a first TA value based on the transmission timing of the terminal device on the second carrier, the downlink timing of the first cell and the timing advance TA offset value of the first cell, where the first TA value is the TA value of the terminal device on the first carrier.

19. The device according to claim 18, characterized in that The same carrier as the second carrier exists in valid carriers of the first cell.

20. The device according to claim 19, characterized in that Also includes: When the carrier of the terminal device in the second cell is the third carrier and there is no carrier identical to the third carrier among the valid carriers of the first cell, the terminal device switches to the second carrier in the second cell.

21. The device according to any one of claims 18 to 20, characterized in that: The device further comprises: The transceiver unit is used to receive first indication information sent by the second network device, where the first indication information is used to indicate that the carrier used by the terminal device for uplink transmission in the first cell is the first carrier, and the second network device is the network device corresponding to the second cell.

22. The device according to claim 21, characterized in that The transceiver unit is further configured to receive first information sent by a second network device, where the first information includes a TA offset value of the first cell.

23. The device according to claim 22, characterized in that The first information further includes: at least one of a time slot offset value between the first cell and the second cell, a system frame number offset value between the first cell and the second cell, and a frame boundary offset value between the first cell and the second cell; The processing unit determining the first TA value according to the transmission timing of the terminal device on the second carrier, the downlink timing of the first cell, and the TA offset value of the first cell includes: A first TA value is determined based on the transmission timing of the terminal device on the second carrier, the downlink timing of the first cell and the first information.

24. The device according to claim 23, characterized in that The first TA value satisfies the following formula: or or or or Among them, N TA is the first TA value, T tt is the transmission timing of the terminal device on the second carrier, T is the downlink timing of the first cell, N TA-offset is the TA offset value of the first cell, T C =1 / (Δf max ·N f ), Δf max =480·103Hz and N f =4096, T slot-offset is the time slot offset between the first cell and the second cell, T sfn-offset is the system frame number offset between the first cell and the second cell, the T Fb-offset is the frame boundary offset value between the first cell and the second cell.

25. The device according to claim 21, characterized in that The transceiver unit is further configured to receive second indication information sent by a second network device, where the second indication information is used to indicate the first cell, and the second indication information includes an identification ID of the first cell.

26. The device according to claim 21, characterized in that The processing unit is further configured to determine N fourth cells based on the measurement result of the third cell and the information of the third cell, where N is an integer greater than or equal to 1, and the valid carrier of the third cell and the valid carrier of the second cell have at least one identical carrier; The transceiver unit is further configured to send indication information of the N fourth cells to the second network device; The transceiver unit is further used to receive second indication information sent by the second network device, where the second indication information is used to indicate the first cell, and the second indication information includes the ID of the first cell, where the first cell is one of the N fourth cells.

27. The device according to claim 26, characterized in that The processing unit determining, according to the measurement result of the third cell and the information of the third cell, the N fourth cells includes: Determine the priority corresponding to each cell in the third cell according to the information of the third cell; The N fourth cells are determined according to the priority corresponding to each cell in the third cells and the measurement result of the third cell.

28. The device according to any one of claims 19 to 27, characterized in that: The device further comprises: The transceiver unit is configured to send second information on the first carrier, where the second information is used to confirm the handover to a first network device, where the first network device is a network device corresponding to the first cell.

29. A communication device, characterized in that: include: a transceiver unit, configured to send first indication information to a terminal device, where the first indication information is used to indicate that a carrier for uplink transmission by the terminal device in the first cell is a first carrier, wherein the first carrier and the second carrier belong to the same frequency band, and the second carrier is a carrier of the terminal device in the second cell; The timing advance TA value of the terminal device on the first carrier is a first TA value, and the first TA value is determined based on the sending timing of the terminal device on the second carrier, the downlink timing of the first cell and the timing advance TA offset value of the first cell.

30. The device according to claim 29, characterized in that The transceiver unit is further used to send first information to the terminal device, where the first information includes a timing advance TA offset value of the first cell.

31. The device according to claim 30, characterized in that The first information also includes: at least one of a time slot offset value between the first cell and the second cell, a system frame number offset value between the first cell and the second cell, and a frame boundary offset value between the first cell and the second cell.

32. The device according to claim 29, characterized in that The device further comprises: a processing unit, configured to determine, based on a measurement result of a third cell and information about the third cell, the first cell, where an effective carrier of the third cell and an effective carrier of the second cell have at least one identical carrier; The transceiver unit is further used to send second indication information to the terminal device, where the second indication information is used to indicate the first cell, and the second indication information includes an identification ID of the first cell.

33. The device according to claim 32, characterized in that The processing unit determining the first cell according to the measurement result of the third cell and the information of the third cell includes: Determine the priority corresponding to each cell in the third cell according to the information of the third cell; The first cell is determined according to the priority corresponding to each cell in the third cells and the measurement result of the third cells.

34. The device according to claim 32, characterized in that The transceiver unit is further configured to receive indication information of N fourth cells sent by the terminal device, where N is an integer greater than or equal to 1, the N fourth cells are determined by the terminal device based on the measurement result of the third cell and the information of the third cell, and the effective carrier of the third cell and the effective carrier of the second cell have at least one identical carrier; The processing unit is further configured to determine the first cell according to the N fourth cells, where the first cell is one of the N fourth cells; The transceiver unit is further used to send second indication information to the terminal device, where the second indication information is used to indicate the first cell, and the second indication information includes the ID of the first cell.

35. A communication device, characterized in that: comprising a processor for executing a computer program, which, when executed, causes the apparatus to Execute the method according to any one of claims 1 to 11; or Execute the method according to any one of claims 12 to 17.

36. The communication device according to claim 35, characterized in that Also included is a memory for storing the computer program.

37. A computer-readable storage medium, characterized in that The computer readable storage medium stores a computer program or computer instructions. When the computer program or computer instructions are executed, The method according to any one of claims 1 to 11 is performed; or The method according to any one of claims 12 to 17 is performed.

38. A chip system, characterized in that: The chip system includes at least one processor, a memory, and an interface circuit, wherein the memory, the interface circuit, and the at least one processor are interconnected via lines, and instructions are stored in at least one memory; when the instructions are executed by the processor, the chip system executes the method according to any one of claims 1 to 11; or Execute the method according to any one of claims 12 to 17.

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