Communication method, apparatus and system

Abstract

The present application provides a communication method, apparatus and system, which can be applicable to handover scenarios, such as an LTM scenario. In the communication method, a terminal device records related information of a handover process in an LTM scenario, and reports the information to a network device, so that the network device can optimize related parameters conveniently, thereby reducing the handover interruption delay, and reducing the probability of handover failure.

Description

Communication method, device and system

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on November 30, 2023, with application number 202311642588.6 and invention name “Communication Methods, Devices and Systems”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of communications, and in particular to a communication method, device, and system. Background Art

[0003] In a scenario where mobility is successful, there may also be potential problems that lead to mobility failure. Potential problems do not represent actual failures, but rather that during the handover process, the handover is not an optimal handover or encounters a near-handover failure. In order to identify non-optimal handover events in a scenario where mobility is successful, the terminal equipment (UE) can record and report parameters during the successful handover process to the network device, namely a successful handover report (SHR), which is used to record mobility-related information of successful handovers with potential problems. The network device can combine the SHR and the UE context to optimize the UE's mobility. However, the current SHR mechanism cannot support mobility scenarios triggered by layer 1 / layer 2 signaling (L1 / L1 triggered mobility, LTM).

[0004] Summary of the Invention

[0005] The present application provides a communication method, device, and system that can reduce handover interruption delay and improve handover success rate in LTM scenarios.

[0006] In the first aspect, a communication method is provided, which can be executed by a terminal device, or by a chip or circuit used for the terminal device, or by a logic module or software that can realize all or part of the functions of the terminal device. This application does not limit this.

[0007] The method includes: a terminal device receives first indication information sent via a media access control control element, the first indication information instructing the terminal device to switch to a target cell, wherein the target cell is one of one or more candidate cells, and the configuration information of the one or more candidate cells is pre-received by the terminal device; the terminal device records a first report, the first report is used to indicate information in the terminal device's execution of layer 1 / layer 2 mobility process; the terminal device sends the first report.

[0008] In this method, handover information is sent via a media access control element (MAC) and the terminal device can pre-receive configuration information for candidate cells, indicating that the terminal device supports handover in LTM scenarios. During the handover process, the terminal device can record relevant information, such as handover parameters. The terminal device reports this information to the network device, which then adjusts and optimizes LTM mobility parameters to improve the success rate of subsequent handovers.

[0009] In some implementations, the terminal device receives first information, where the first information instructs the terminal device to record the first report during a layer 1 or layer 2 mobility process and when a trigger condition is met, wherein the first information includes the trigger condition.

[0010] That is, the network device configures trigger conditions for the terminal device, and the terminal device can record relevant information when the trigger conditions are met. This avoids the terminal device from recording relevant information and reporting it to the network side without filtering upon successful handover, reduces the terminal device's excessive recording of first reports, and thus reduces the terminal device's storage and air interface signaling overhead.

[0011] In some implementations, the trigger condition is related to at least one of the target cell, the running time of the first timer, the running time of the second timer, the running time of the third timer, the running time of the fourth timer, the running time of the fifth timer, or fast recovery,

[0012] The running time of the first timer is the time from when the terminal device receives the first indication information to when the terminal device completes random access or sends the first uplink data.

[0013] The running time of the second timer is the time from when the terminal device detects a physical layer desynchronization problem with the source network device to when the terminal device receives the first indication information.

[0014] The running time of the third timer is the time from when the terminal device triggers the sending of the measurement report to when the terminal device receives the first indication information during the running period of the second timer,

[0015] The running time of the fourth timer is the time from when the terminal device receives the first indication information to when the terminal device transmits the first uplink data or receives the first downlink data.

[0016] The running duration of the fifth timer is the duration from the terminal receiving or applying the radio resource control RRC reconfiguration message with synchronization function to the terminal device completing random access or the terminal device receiving the narrow physical control channel transmission after the first uplink transmission without random access.

[0017] It should be understood that the above conditions are merely examples of conditions for a terminal device to record relevant information. For example, a method of predefining a terminal device to record relevant information at a certain time point or within a certain time period can also be used in this application.

[0018] In some implementations, the trigger condition is related to the target cell, and the trigger condition is: the terminal device has not obtained the available advance timing value of the target cell, and the advance timing value is used by the terminal device to obtain uplink synchronization with the target cell to avoid random access.

[0019] In some implementations, the terminal device failing to obtain the advance timing value of the target cell includes: the terminal device failing to perform early timing acquisition with the target cell, or the terminal device performing early timing acquisition with the target cell and failing to obtain a usable advance timing value.

[0020] In some implementations, the trigger condition is related to the running time of the first timer, and the trigger condition is:

[0021] The running time of the first timer is less than the first threshold value and greater than or equal to the second threshold value,

[0022] The second threshold value is the product of the first threshold value and a first coefficient, and the first coefficient is a positive number less than 1; or the second threshold value is a value less than the first threshold value.

[0023] In some implementations, the trigger condition is related to the running time of the second timer, and the trigger condition is: the running time of the second timer is less than a third threshold value and greater than or equal to a fourth threshold value, wherein the fourth threshold value is the product of the third threshold value and a second coefficient, and the second coefficient is a positive number less than 1, or the fourth threshold value is a value less than the third threshold value.

[0024] In some implementations, the trigger condition is related to the running time of the third timer, and the trigger condition is: the running time of the third timer is less than the fifth threshold value and greater than or equal to the sixth threshold value, wherein the sixth threshold value is the product of the fifth threshold value and the third coefficient, and the third coefficient is a positive number less than 1, or the sixth threshold value is a value less than the fifth threshold value.

[0025] In some implementations, the trigger condition is related to the running time of the fourth timer, and the trigger condition is: the running time of the fourth timer is greater than or equal to a seventh threshold value.

[0026] In some implementations, the trigger condition is related to the running time of the fifth timer, and the trigger condition is: the running time of the fifth timer is less than the eighth threshold value and greater than or equal to the ninth threshold value, wherein the ninth threshold value is the product of the eighth threshold value and the fourth coefficient, and the fourth coefficient is a positive number less than 1, or the ninth threshold value is a value less than the eighth threshold value.

[0027] In some implementations, the trigger condition is related to the rapid recovery, and the trigger condition is: the terminal device performs rapid recovery based on the one or more candidate cells to access one of the candidate cells.

[0028] In some implementations, the first report includes one or more of the following information: one or more of the triggering conditions of the first report that are met; early advance timing information; cell information; target cell access information; and fast process recovery information.

[0029] In this method, the first report will report the reasons for triggering the report and related parameters, so that the network side can perform root cause analysis and optimize related parameters based on the first report to reduce the data transmission terminal delay and further improve the accuracy of network equipment optimization parameters.

[0030] In some implementations, the first report includes early advance timing information, and the early advance timing information includes whether the terminal device has performed early advance timing in the target cell, the number of times the terminal device receives a PDCCH instruction indicating the target cell, the beam identification information attempted to perform early advance timing, the number of preamble codes sent through the attempted beam, physical random access channel PRACH resource information, information corresponding to the candidate cell indicating that the terminal device performs early advance timing, or at least one of the information of the target cell.

[0031] In this manner, the network side optimizes the early timing-related processes and parameters based on the first report, thereby increasing the probability of random access-free switching and reducing data transmission interruption time.

[0032] In some implementations, the first report includes quick recovery process information, which includes information about one or more candidate cells for quick recovery, and / or the duration from the failure of the terminal device switching to the successful access to one of the one or more candidate cells.

[0033] In this manner, the network side optimizes the LTM mobility parameters, such as the LTM target cell, based on the first report, to improve the success probability of LTM handover and reduce the data transmission interruption time.

[0034] In some implementations, the first report also includes time information, and the time information includes at least one item of the running duration of the first timer, the running duration of the second timer, the running duration of the third timer, the running duration of the fourth timer, the running duration of the fifth timer, and the time from the terminal device receiving the configuration information of the one or more candidate cells or receiving the first PDCCH instruction or receiving the last PDCCH instruction to the terminal device receiving the first indication information.

[0035] In this method, the network side optimizes the LTM process and related parameters based on the first report, such as executing the early advance timing process and LTM switching indication at a reasonable time point / segment, improving the success probability of LTM switching without random access, and thus reducing data transmission interruption time.

[0036] In some implementations, the first report also includes cell information, the cell information includes information about the current service cell of the terminal device, the target cell of the terminal device, or at least one of the neighboring cells. The cell information includes cell identification information, layer 1 and / or layer 3 measurement results corresponding to the cell, and whether the neighboring cell belongs to the one or more candidate cells. The neighboring cells are cells other than the current service cell measured by the terminal device, and the one or more candidate cells are cells that the terminal device is allowed to access when the handover fails.

[0037] In this manner, the network side optimizes the LTM mobility parameters, such as the LTM target cell, based on the first report, to improve the success probability of LTM handover and reduce the data transmission interruption time.

[0038] In some implementations, the first report also includes the target cell access information, and the target cell access information includes the access type used by the terminal device to access the target cell, the access type is random access-free or random access, or the access type is random access-free, or whether the access type is random access-free.

[0039] In certain implementations, when the access type is random access, the target cell access information further includes information on a two-step random access process and / or a four-step random access process.

[0040] In this manner, the network side optimizes the LTM process and related parameters based on the first report, improves the success probability of LTM switching without random access, reduces the interruption time of LTM switching based on random access, and thus reduces the data transmission interruption time.

[0041] On the second aspect, a communication method is provided, which can be executed by a network device, or by a chip or circuit used for a network device, or by a logic module or software that can realize all or part of the functions of the network device. This application does not limit this.

[0042] The method includes: the network device sends a first indication message, the first indication message instructs the terminal device to switch to a target cell, the first indication message is sent via a media access control control element, wherein the target cell is one of one or more candidate cells, and the information of the one or more candidate cells is pre-received by the terminal device; the network device receives the first report, and the first report is used to indicate information in the process of the terminal device executing layer 1 / layer 2 mobility.

[0043] In some implementations, the network device sends first information, where the first information instructs the terminal device to record the first report during a layer 1 or layer 2 mobility process and when a trigger condition is met, wherein the first information includes the trigger condition.

[0044] In some implementations, the trigger condition is related to at least one of the target cell, the running time of the first timer, the running time of the second timer, the running time of the third timer, the running time of the fourth timer, the running time of the fifth timer, or fast recovery,

[0045] The running time of the first timer is the time from when the terminal device receives the first indication information to when the terminal device completes random access or sends the first uplink data.

[0046] The running time of the second timer is the time from when the terminal device detects a physical layer desynchronization problem with the source network device to when the terminal device receives the first indication information.

[0047] The running time of the third timer is the time from when the terminal device triggers the sending of the measurement report to when the terminal device receives the first indication information during the running period of the second timer,

[0048] The running time of the fourth timer is the time from when the terminal device receives the first indication information to when the terminal device transmits the first uplink data or receives the first downlink data.

[0049] The running duration of the fifth timer is the duration from the terminal receiving or applying the radio resource control RRC reconfiguration message with synchronization function to the terminal device completing random access or the terminal device receiving the downlink physical control channel transmission after the first uplink transmission when random access is not required.

[0050] In some implementations, the triggering condition is related to the target cell, and the triggering condition is:

[0051] The terminal device does not have an available advance timing value for the target cell, and the advance timing value is used by the terminal device to obtain uplink synchronization with the target cell to avoid random access.

[0052] In some implementations, the trigger condition is related to the running time of the first timer, and the trigger condition is: the running time of the first timer is less than a first threshold value and greater than or equal to a second threshold value, wherein the second threshold value is the product of the first threshold value and a first coefficient, and the first coefficient is a positive number less than 1; or, the second threshold value is a value less than the first threshold value.

[0053] In some implementations, the trigger condition is related to the running time of the second timer, and the trigger condition is: the running time of the second timer is less than a third threshold value and greater than or equal to a fourth threshold value, wherein the fourth threshold value is the product of the third threshold value and a second coefficient, and the second coefficient is a positive number less than 1, or the fourth threshold value is a value less than the third threshold value.

[0054] In some implementations, the trigger condition is related to the running time of the third timer, and the trigger condition is: the running time of the third timer is less than the fifth threshold value and greater than or equal to the sixth threshold value, wherein the sixth threshold value is the product of the fifth threshold value and the third coefficient, and the third coefficient is a positive number less than 1, or the sixth threshold value is a value less than the fifth threshold value.

[0055] In some implementations, the trigger condition is related to the running time of the fourth timer, and the trigger condition is: the running time of the fourth timer is greater than or equal to a seventh threshold value.

[0056] In some implementations, the trigger condition is related to the running time of the fifth timer, and the trigger condition is: the running time of the fifth timer is less than the eighth threshold value and greater than or equal to the ninth threshold value, wherein the ninth threshold value is the product of the eighth threshold value and the fourth coefficient, and the fourth coefficient is a positive number less than 1, or the ninth threshold value is a value less than the eighth threshold value.

[0057] In some implementations, the trigger condition is related to the rapid recovery, and the trigger condition is: the terminal device performs rapid recovery based on the one or more candidate cells to access one of the candidate cells.

[0058] In some implementations, the first report includes one or more of the following information:

[0059] One or more of the triggering conditions of the first report being met; early advance timing information; cell information; target cell access information; fast process recovery information.

[0060] In some implementations, the first report includes early advance timing information, and the early advance timing information includes whether the terminal device has performed early advance timing in the target cell, the number of times the terminal device receives a PDCCH instruction indicating the target cell, the beam identification information attempted to perform early advance timing, the number of preamble codes sent through the attempted beam, physical random access channel PRACH resource information, information corresponding to the candidate cell indicating that the terminal device performs early advance timing, or at least one of the information of the target cell.

[0061] In some implementations, the first report includes quick recovery process information, which includes information about one or more candidate cells for quick recovery, and / or the duration from the failure of the terminal device switching to the successful access to one of the one or more candidate cells.

[0062] In some implementations, the first report also includes time information, and the time information includes at least one of the running duration of the first timer, the running duration of the second timer, the running duration of the third timer, the running duration of the fourth timer, the running duration of the fifth timer, and the duration between the terminal device receiving the candidate cell preconfiguration or receiving the first PDCCH instruction or receiving the last PDCCH instruction and the terminal device receiving the first indication information.

[0063] In some implementations, the first report also includes cell information, the cell information includes information about the current service cell of the terminal device, the target cell of the terminal device, or at least one of the neighboring cells. The cell information includes cell identification information, layer 1 and / or layer 3 measurement results corresponding to the cell, and whether the neighboring cell belongs to the one or more candidate cells. The neighboring cells are cells other than the current service cell measured by the terminal device, and the one or more candidate cells are cells that the terminal device is allowed to access when the handover fails.

[0064] In some implementations, the first report also includes the target cell access information, and the target cell access information includes the access type used by the terminal device to access the target cell, and the access type is random access-free or random access, or the access type is random access-free.

[0065] In certain implementations, when the access type is random access, the target cell access information further includes information on a two-step random access process and / or a four-step random access process.

[0066] It should be understood that the second aspect is an implementation method on the network device side corresponding to the first aspect. The explanations, supplements and descriptions of the beneficial effects of the first aspect are also applicable to the second aspect and will not be repeated here.

[0067] According to a third aspect, a communication device is provided, comprising a transceiver unit and a processing unit, wherein the transceiver unit is used to receive a first indication message sent via a media access control control element, wherein the first indication message instructs the terminal device to switch to a target cell, wherein the target cell is one of one or more candidate cells, and the configuration information of the one or more candidate cells is pre-received by the terminal device; the processing unit is used to record a first report, wherein the first report is used to indicate information in the process of the terminal device executing layer 1 / layer 2 mobility; and the transceiver unit is also used to send the first report.

[0068] In some implementations, the transceiver unit is further used to receive first information, where the first information indicates that the terminal device records the first report during the mobility process of layer 1 or layer 2 and when a trigger condition is met, wherein the first information includes the trigger condition.

[0069] In some implementations, the trigger condition is related to at least one of the target cell, the running time of the first timer, the running time of the second timer, the running time of the third timer, the running time of the fourth timer, the running time of the fifth timer, or fast recovery,

[0070] The running time of the first timer is the time from when the terminal device receives the first indication information to when the terminal device completes random access or sends the first uplink data.

[0071] The running time of the second timer is the time from when the terminal device detects a physical layer desynchronization problem with the source network device to when the terminal device receives the first indication information.

[0072] The running time of the third timer is the time from when the terminal device triggers the sending of the measurement report to when the terminal device receives the first indication information during the running period of the second timer,

[0073] The running time of the fourth timer is the time from when the terminal device receives the first indication information to when the terminal device transmits the first uplink data or receives the first downlink data.

[0074] The running duration of the fifth timer is the duration from the terminal receiving or applying the radio resource control RRC reconfiguration message with synchronization function to the terminal device completing random access or the terminal device receiving the downlink physical control channel transmission after the first uplink transmission when random access is not required.

[0075] It should be understood that the above conditions are merely examples of conditions for a terminal device to record relevant information. For example, a method of predefining a terminal device to record relevant information at a certain time point or within a certain time period can also be used in this application.

[0076] In some implementations, the trigger condition is related to the target cell, and the trigger condition is: the terminal device has not obtained the available advance timing value of the target cell, and the advance timing value is used by the terminal device to obtain uplink synchronization with the target cell to avoid random access.

[0077] In some implementations, the terminal device failing to obtain the advance timing value of the target cell includes: the terminal device failing to perform early timing acquisition with the target cell, or the terminal device performing early timing acquisition with the target cell and failing to obtain a usable advance timing value.

[0078] In some implementations, the trigger condition is related to the running time of the first timer, and the trigger condition is:

[0079] The running time of the first timer is less than the first threshold value and greater than or equal to the second threshold value,

[0080] The second threshold value is the product of the first threshold value and a first coefficient, and the first coefficient is a positive number less than 1; or the second threshold value is a value less than the first threshold value.

[0081] In some implementations, the trigger condition is related to the running time of the second timer, and the trigger condition is: the running time of the second timer is less than a third threshold value and greater than or equal to a fourth threshold value, wherein the fourth threshold value is the product of the third threshold value and a second coefficient, and the second coefficient is a positive number less than 1, or the fourth threshold value is a value less than the third threshold value.

[0082] In some implementations, the trigger condition is related to the running time of the third timer, and the trigger condition is: the running time of the third timer is less than the fifth threshold value and greater than or equal to the sixth threshold value, wherein the sixth threshold value is the product of the fifth threshold value and the third coefficient, and the third coefficient is a positive number less than 1, or the sixth threshold value is a value less than the fifth threshold value.

[0083] In some implementations, the trigger condition is related to the running time of the fourth timer, and the trigger condition is: the running time of the fourth timer is greater than or equal to a seventh threshold value.

[0084] In some implementations, the trigger condition is related to the running time of the fifth timer, and the trigger condition is: the running time of the fifth timer is less than the eighth threshold value and greater than or equal to the ninth threshold value, wherein the ninth threshold value is the product of the eighth threshold value and the fourth coefficient, and the fourth coefficient is a positive number less than 1, or the ninth threshold value is a value less than the eighth threshold value.

[0085] In some implementations, the trigger condition is related to the rapid recovery, and the trigger condition is: the terminal device performs rapid recovery based on the one or more candidate cells to access one of the candidate cells.

[0086] In some implementations, the first report includes one or more of the following information: one or more of the triggering conditions of the first report being met; early advance timing information; cell information; target cell access information; and fast process recovery information.

[0087] In some implementations, the first report includes early advance timing information, and the early advance timing information includes whether the terminal device has performed early advance timing in the target cell, the number of times the terminal device receives a PDCCH instruction indicating the target cell, the beam identification information attempted to perform early advance timing, the number of preamble codes sent through the attempted beam, physical random access channel PRACH resource information, information corresponding to the candidate cell indicating that the terminal device performs early advance timing, or at least one of the information of the target cell.

[0088] In some implementations, the first report includes quick recovery process information, which includes information about one or more candidate cells for quick recovery, and / or the duration from the failure of the terminal device switching to the successful access to one of the one or more candidate cells.

[0089] In some implementations, the first report also includes time information, and the time information includes at least one of the running duration of the first timer, the running duration of the second timer, the running duration of the third timer, the running duration of the fourth timer, the running duration of the fifth timer, the running duration of the fourth timer, and the time from the terminal device receiving the configuration information of the one or more candidate cells or receiving the first PDCCH instruction or receiving the last PDCCH instruction to the terminal device receiving the first indication information.

[0090] In some implementations, the first report also includes cell information, the cell information includes information about the current service cell of the terminal device, the target cell of the terminal device, or at least one of the neighboring cells. The cell information includes cell identification information, layer 1 and / or layer 3 measurement results corresponding to the cell, and whether the neighboring cell belongs to the one or more candidate cells. The neighboring cells are cells other than the current service cell measured by the terminal device, and the one or more candidate cells are cells that the terminal device is allowed to access when the handover fails.

[0091] In some implementations, the first report also includes the target cell access information, and the target cell access information includes the access type used by the terminal device to access the target cell, and the access type is random access-free or random access, or the access type is random access-free.

[0092] In certain implementations, when the access type is random access, the target cell access information further includes information on a two-step random access process and / or a four-step random access process.

[0093] In a fourth aspect, a communication device is provided, comprising a transceiver unit, wherein the transceiver unit is used to send a first indication message, wherein the first indication message instructs the terminal device to switch to a target cell, and the first indication message is sent via a media access control control element, wherein the target cell is one of one or more candidate cells, and the information of the one or more candidate cells is pre-received by the terminal device; the transceiver unit is also used to receive the first report, which is used to indicate information in the process of the terminal device executing layer 1 / layer 2 mobility.

[0094] In some implementations, the transceiver unit is further used to send first information, where the first information instructs the terminal device to record the first report during the mobility process of layer 1 or layer 2 and when a trigger condition is met, wherein the first information includes the trigger condition.

[0095] In some implementations, the trigger condition is related to at least one of the target cell, the running time of the first timer, the running time of the second timer, the running time of the third timer, the running time of the fourth timer, the running time of the fifth timer, or fast recovery,

[0096] The running time of the first timer is the time from when the terminal device receives the first indication information to when the terminal device completes random access or sends the first uplink data.

[0097] The running time of the second timer is the time from when the terminal device detects a physical layer desynchronization problem with the source network device to when the terminal device receives the first indication information.

[0098] The running time of the third timer is the time from when the terminal device triggers the sending of the measurement report to when the terminal device receives the first indication information during the running period of the second timer,

[0099] The running time of the fourth timer is the time from when the terminal device receives the first indication information to when the terminal device transmits the first uplink data or receives the first downlink data.

[0100] The running duration of the fifth timer is the duration from the terminal receiving or applying the radio resource control RRC reconfiguration message with synchronization function to the terminal device completing random access or the terminal device receiving the downlink physical control channel transmission after the first uplink transmission when random access is not required.

[0101] In some implementations, the triggering condition is related to the target cell, and the triggering condition is:

[0102] The terminal device does not have an available advance timing value for the target cell, and the advance timing value is used by the terminal device to obtain uplink synchronization with the target cell to avoid random access.

[0103] In some implementations, the trigger condition is related to the running time of the first timer, and the trigger condition is: the running time of the first timer is less than a first threshold value and greater than or equal to a second threshold value, wherein the second threshold value is the product of the first threshold value and a first coefficient, and the first coefficient is a positive number less than 1; or, the second threshold value is a value less than the first threshold value.

[0104] In some implementations, the trigger condition is related to the running time of the second timer, and the trigger condition is: the running time of the second timer is less than a third threshold value and greater than or equal to a fourth threshold value, wherein the fourth threshold value is the product of the third threshold value and a second coefficient, and the second coefficient is a positive number less than 1, or the fourth threshold value is a value less than the third threshold value.

[0105] In some implementations, the trigger condition is related to the running time of the third timer, and the trigger condition is: the running time of the third timer is less than the fifth threshold value and greater than or equal to the sixth threshold value, wherein the sixth threshold value is the product of the fifth threshold value and the third coefficient, and the third coefficient is a positive number less than 1, or the sixth threshold value is a value less than the fifth threshold value.

[0106] In some implementations, the trigger condition is related to the running time of the fourth timer, and the trigger condition is: the running time of the fourth timer is greater than or equal to a seventh threshold value.

[0107] In some implementations, the trigger condition is related to the running time of the fifth timer, and the trigger condition is: the running time of the fifth timer is less than the eighth threshold value and greater than or equal to the ninth threshold value, wherein the ninth threshold value is the product of the eighth threshold value and the fourth coefficient, and the fourth coefficient is a positive number less than 1, or the ninth threshold value is a value less than the eighth threshold value.

[0108] In some implementations, the trigger condition is related to the rapid recovery, and the trigger condition is: the terminal device performs rapid recovery based on the one or more candidate cells to access one of the candidate cells.

[0109] In some implementations, the first report includes one or more of the following information: one or more of the triggering conditions of the first report being met; early advance timing information; cell information; target cell access information; and fast process recovery information.

[0110] In some implementations, the first report includes early advance timing information, and the early advance timing information includes whether the terminal device has performed early advance timing in the target cell, the number of times the terminal device receives a PDCCH instruction indicating the target cell, the beam identification information attempted to perform early advance timing, the number of preamble codes sent through the attempted beam, physical random access channel PRACH resource information, information corresponding to the candidate cell indicating that the terminal device performs early advance timing, or at least one of the information of the target cell.

[0111] In some implementations, the first report includes quick recovery process information, which includes information about one or more candidate cells for quick recovery, and / or the duration from the failure of the terminal device switching to the successful access to one of the one or more candidate cells.

[0112] In some implementations, the first report also includes time information, and the time information includes at least one of the running duration of the first timer, the running duration of the second timer, the running duration of the third timer, the running duration of the fourth timer, the running duration of the fifth timer, and the duration between the terminal device receiving the candidate cell preconfiguration or receiving the first PDCCH instruction or receiving the last PDCCH instruction and the terminal device receiving the first indication information.

[0113] In some implementations, the first report also includes cell information, the cell information includes information about the current service cell of the terminal device, the target cell of the terminal device, or at least one of the neighboring cells. The cell information includes cell identification information, layer 1 and / or layer 3 measurement results corresponding to the cell, and whether the neighboring cell belongs to the one or more candidate cells. The neighboring cells are cells other than the current service cell measured by the terminal device, and the one or more candidate cells are cells that the terminal device is allowed to access when the handover fails.

[0114] In some implementations, the first report also includes the target cell access information, and the target cell access information includes the access type used by the terminal device to access the target cell, and the access type is random access-free or random access, or the access type is random access-free.

[0115] In certain implementations, when the access type is random access, the target cell access information further includes information on a two-step random access process and / or a four-step random access process.

[0116] In a fifth aspect, the present application provides a communication device, comprising an interface circuit and a processor, wherein the interface circuit is used to implement the function of the transceiver module in the third aspect, and the processor is used to implement the function of the processing module in the third aspect.

[0117] In a sixth aspect, the present application provides a communication device, comprising an interface circuit and a processor, wherein the interface circuit is used to implement the function of the transceiver module in the fourth aspect, and the processor is used to implement the function of the processing module in the sixth aspect.

[0118] In the seventh aspect, the present application provides a computer-readable medium storing a program code for execution on a terminal device, the program code comprising instructions for executing the method of the first aspect, or any possible manner in the first aspect, or all possible manners in the first aspect.

[0119] In an eighth aspect, an embodiment of the present application provides a computer-readable medium storing a program code for execution by a network device, the program code including instructions for executing the method of the second aspect, or the third aspect, or any possible manner in the second aspect, or any possible manner in the third aspect, or all possible manners in the second aspect, or all possible manners in the third aspect.

[0120] In the ninth aspect, a computer program product storing computer-readable instructions is provided, which, when the computer-readable instructions are executed on a computer, enables the computer to execute the method of the first aspect, or any possible method of the first aspect, or all possible methods of the first aspect.

[0121] In the tenth aspect, a computer program product storing computer-readable instructions is provided, which, when the computer-readable instructions are run on a computer, enables the computer to execute the method of the above-mentioned second aspect, or any possible method of the second aspect, or all possible methods of the second aspect.

[0122] In the eleventh aspect, a communication system is provided, which includes a device having functions of implementing the above-mentioned first aspect, or any possible manner in the first aspect, or all possible manners in the first aspect, the second aspect, or any possible manner in the second aspect, or all possible manners in the second aspect, and various possible designed functions.

[0123] In the twelfth aspect, a processor is provided, which is coupled to a memory and is used to execute the method of the above-mentioned first aspect, or any possible method of the first aspect, or all possible methods of the first aspect.

[0124] In a thirteenth aspect, a processor is provided, coupled to a memory, for executing the method of the second aspect, or any possible manner of the second aspect, or all possible manners of the second aspect.

[0125] In a fourteenth aspect, a chip system is provided, comprising a processor and a memory configured to execute computer programs or instructions stored in the memory, so that the chip system implements the method of any of the aforementioned first or second aspects, as well as any possible implementation of either aspect. The chip system may be composed of a chip alone, or may include a chip and other discrete components. BRIEF DESCRIPTION OF THE DRAWINGS

[0126] FIG1 is a schematic diagram of a wireless communication system applicable to an embodiment of the present application.

[0127] FIG2 is a schematic diagram of a protocol stack applicable to an embodiment of the present application.

[0128] FIG3 is a schematic diagram of an ORAN system applicable to an embodiment of the present application.

[0129] FIG4 is a schematic flowchart of a contention-based four-step random access provided in an embodiment of the present application.

[0130] FIG5 is a schematic flowchart of a contention-based two-step random access provided in an embodiment of the present application.

[0131] FIG6 is a schematic diagram of a communication method provided in an embodiment of the present application.

[0132] FIG7 is a schematic diagram of another communication method provided in an embodiment of the present application.

[0133] FIG8 is a flow chart of a communication method provided in an embodiment of the present application.

[0134] FIG9 is a schematic diagram of two switching processes provided in an embodiment of the present application.

[0135] FIG10 shows a schematic block diagram of a communication device provided in an embodiment of the present application.

[0136] FIG11 shows a schematic structural diagram of a communication device provided in an embodiment of the present application.

[0137] FIG12 shows a schematic diagram of a chip system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0138] The technical solution in this application will be described below with reference to the accompanying drawings.

[0139] The technical solutions provided in this application can be applied to various communication systems, such as: fifth generation (5G) or new radio (NR) systems, long term evolution (LTE) systems, LTE frequency division duplex (FDD) systems, LTE time division duplex (TDD) systems, etc. The technical solutions provided in this application can also be applied to future communication systems, such as the sixth generation mobile communication system. The technical solutions provided in this application can also be applied to device to device (D2D) communication, vehicle-to-everything (V2X) communication, machine to machine (M2M) communication, machine type communication (MTC), and Internet of Things (IoT) communication systems or other communication systems.

[0140] The terminal devices in the embodiments of the present application include various devices with wireless communication functions, which can be used to connect people, objects, machines, etc. The terminal devices can be widely used in various scenarios, such as: cellular communication, D2D, V2X, peer to peer (P2P), M2M, MTC, IoT, virtual reality (VR), augmented reality (AR), industrial control, autonomous driving, telemedicine, smart grid, smart furniture, smart office, smart wearable, smart transportation, smart city drones, robots, remote sensing, passive sensing, positioning, navigation and tracking, autonomous delivery, etc. The terminal device can be a terminal in any of the above scenarios, such as an MTC terminal, an IoT terminal, etc. The terminal device may be a user equipment (UE) of the third generation partnership project (3GPP) standard, a terminal, a fixed device, a mobile station device or a mobile device, a subscriber unit, a handheld device, a vehicle-mounted device, a wearable device, a cellular phone, a smart phone, a SIP phone, a wireless data card, a personal digital assistant (PDA), a computer, a tablet computer, a notebook computer, a wireless modem, a handheld device, a laptop computer, a computer with wireless transceiver function, a smart book, a vehicle, a satellite, a global positioning system (GPS) device, a target tracking device, an aircraft (such as a drone, a helicopter, a multi-copter, a quadcopter, or an airplane), a ship, a remote control device, a smart home device, an industrial device, or a device built into the above-mentioned device (such as a communication module, a modem or a chip in the above-mentioned device), or other processing devices connected to a wireless modem. For ease of description, the terminal device will be described below by taking the terminal or UE as an example.

[0141] It should be understood that in some scenarios, a UE can also be used to act as a base station. For example, a UE can act as a scheduling entity that provides sidelink signals between UEs in scenarios such as V2X, D2D, or P2P.

[0142] In the embodiments of the present application, the device for implementing the function of the terminal device can be the terminal device, or it can be a device that can support the terminal device to implement the function, such as a chip system or chip, which can be installed in the terminal device. In the embodiments of the present application, the chip system can be composed of a chip, or it can include a chip and other discrete devices.

[0143] The network device in the embodiments of the present application may be a device for communicating with a terminal device, and may also be referred to as an access network device or a radio access network device. For example, the network device may be a base station. The network device in the embodiments of the present application may refer to a radio access network (RAN) node (or device) that connects a terminal device to a wireless network. Base station can broadly cover various names as follows, or replace the following names, such as: NodeB, evolved NodeB (eNB), next generation NodeB (gNB), relay station, access point, transmission point (TRP), transmission point (TP), master station, auxiliary station, multi-standard wireless (motor slide retainer, MSR) node, home base station, network controller, access node, wireless node, access point (AP), transmission node, transceiver node, baseband unit (BBU), remote radio unit (RRU), active antenna unit (AAU), remote radio head (RRH), central unit (CU), distributed unit (DU), positioning node, etc. The base station can be a macro base station, a micro base station, a relay node, a donor node or the like, or a combination thereof. The base station can also refer to a communication module, modem or chip used to be set in the aforementioned device or apparatus. The base station can also be a mobile switching center and a device that performs base station functions in D2D, V2X, and M2M communications, a network-side device in a 6G network, or a device that performs base station functions in future communication systems. The base station can support networks with the same or different access technologies. The embodiments of this application do not limit the specific technology and specific device form used by the network equipment.

[0144] Base stations can be fixed or mobile. For example, a helicopter or drone can be configured to act as a mobile base station, and one or more cells can move based on the location of the mobile base station. In other examples, a helicopter or drone can be configured to act as a device that communicates with another base station.

[0145] In the embodiments of the present application, the device for implementing the function of the network device can be a terminal device, or a device that can support the network device to implement the function, such as a chip system or chip, which can be installed in the network device. In the embodiments of the present application, the chip system can be composed of a chip, or it can include a chip and other discrete devices.

[0146] The network equipment and terminal devices can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; they can also be deployed on water; they can also be deployed in the air on aircraft, balloons, and satellites. The embodiments of this application do not limit the scenarios in which the network equipment and terminal devices are located.

[0147] First, a brief introduction to the network architecture applicable to the embodiments of the present application is given as follows.

[0148] FIG1 is a schematic diagram of a wireless communication system 100 applicable to an embodiment of the present application. As shown in FIG1 , the wireless communication system 100 may include at least one network device, such as the network device 110a shown in FIG1 . The wireless communication system 100 may also include at least one terminal device, such as the terminal device 120a and the terminal device 120b shown in FIG1 . Both the network device and the terminal device may be configured with multiple antennas, and the network device and the terminal device may communicate using multi-antenna technology. Terminal devices may also communicate with each other. For example, terminal devices may communicate directly with each other. For another example, terminal devices may communicate with each other through other communication devices, such as network devices or other terminal devices.

[0149] When a network device communicates with a terminal device, the network device can manage one or more cells, and a cell can have an integer number of terminal devices. Optionally, network device 110a and terminal device 120a form a single-cell communication system. Without loss of generality, the cell is referred to as cell #1. Network device 110a can be a network device in cell #1, or network device 110a can serve a terminal device (e.g., terminal device 120a) in cell #1.

[0150] It should be noted that a cell can be understood as an area within the coverage range of wireless signals of network equipment.

[0151] It should be understood that Figure 1 is a simplified schematic diagram for ease of understanding, and the wireless communication system 100 may also include other network devices or other terminal devices, which are not shown in Figure 1. The embodiments of the present application can be applied to any communication scenario in which a transmitting device and a receiving device communicate.

[0152] 1) The terminal 120 may also be referred to as a terminal device, user equipment (UE), mobile station, mobile terminal, etc. The terminal can be widely used in various scenarios, for example, device-to-device (D2D), vehicle-to-everything (V2X) communication, machine-type communication (MTC), Internet of Things (IOT), virtual reality, augmented reality, industrial control, autonomous driving, telemedicine, smart grid, smart furniture, smart office, smart wearable, smart transportation, smart city, etc. The terminal may be a mobile phone, a tablet computer, a computer with wireless transceiver function, a wearable device, a vehicle, a drone, a helicopter, an airplane, a ship, a robot, a robotic arm, a smart home device, etc. The embodiments of the present application do not limit the device form of the terminal.

[0153] 2) RAN node 110, sometimes also referred to as access network equipment, RAN entity or access node, etc., constitutes a part of the communication system to help terminals achieve wireless access. The multiple RAN nodes 110 in the communication system 1000 can be nodes of the same type or different types. In some scenarios, the roles of the RAN node 110 and the terminal 120 are relative. For example, the network element 120i in Figure 1 can be a helicopter or a drone, which can be configured as a mobile base station. For those terminals 120j that access the RAN 100 through the network element 120i, the network element 120i is a base station; but for the base station 110a, the network element 120i is a terminal. The RAN node 110 and the terminal 120 are sometimes referred to as communication devices. For example, the network elements 110a and 110b in Figure 1 can be understood as communication devices with base station functions, and the network elements 120a-120j can be understood as communication devices with terminal functions.

[0154] In one possible scenario, a RAN node may be a base station, an evolved NodeB (eNodeB), an access point (AP), a transmission reception point (TRP), a next-generation NodeB (gNB), a next-generation base station in a sixth-generation (6G) mobile communication system, a base station in a future mobile communication system, or an access node in a WiFi system. A RAN node may be a macro base station (such as 110a in Figure 1 ), a micro base station or an indoor station (such as 110b in Figure 1 ), a relay node or a donor node, or a wireless controller in a CRAN scenario. Alternatively, a RAN node may be a server, a wearable device, a vehicle, or an onboard device. For example, the access network device in vehicle-to-everything (V2X) technology may be a roadside unit (RSU).

[0155] In another possible scenario, multiple RAN nodes collaborate to assist terminals in achieving wireless access, with different RAN nodes implementing portions of the base station's functionality. For example, a RAN node can be a centralized unit (CU), a distributed unit (DU), a CU-control plane (CP), a CU-user plane (UP), or a radio unit (RU). The CU and DU can be separate or included in the same network element, such as the baseband unit (BBU). The CU and DU nodes split the gNB's protocol layers, centrally controlling some protocol layer functions within the CU and distributing some or all of the remaining protocol layer functions within the DU, which is then centrally controlled by the CU. As an implementation method, as shown in Figure 2, the CU is deployed with the radio resource control (RRC) layer, the PDCP layer, and the service data adaptation protocol (SDAP) layer in the protocol stack; the DU is deployed with the radio link control (RLC) layer, the media access control (MAC) layer, and the physical layer (PHY) in the protocol stack. Thus, the CU has the processing capabilities of RRC, PDCP, and SDAP. The DU has the processing capabilities of RLC, MAC, and PHY. It will be understood that the above functional division is only an example and does not constitute a limitation on the CU and DU. The RU may be included in a radio frequency device or a radio frequency unit, for example, in a remote radio unit (RRU), an active antenna unit (AAU), or a remote radio head (RRH).

[0156] In different systems, CU (or CU-CP and CU-UP), DU or RU may also have different names, but those skilled in the art can understand their meanings. For example, in the ORAN system, CU may also be called O-CU (open CU), DU may also be called O-DU, CU-CP may also be called O-CU-CP, CU-UP may also be called O-CU-UP, and RU may also be called O-RU. For the convenience of description, this application takes CU, CU-CP, CU-UP, DU and RU as examples for description. Any unit of CU (or CU-CP, CU-UP), DU and RU in this application can be implemented by a software module, a hardware module, or a combination of a software module and a hardware module. For specific protocol layer functions, please refer to Table 1:

[0157] Table 1. Correspondence between ORAN access network equipment (network element modules) and their achievable protocol layer functions

[0158] For example, FIG3 is a schematic diagram of an ORAN system, which may include one or more CUs, DUs, and RUs.

[0159] 3) Core network equipment refers to the equipment in the core network (CN) that provides service support for the terminal. At present, some examples of core network equipment are: access and mobility management function (AMF) entity, session management function (SMF) entity, user plane function (UPF) entity, etc., which are not listed here one by one. Among them, the AMF entity can be responsible for terminal access management and mobility management; the SMF entity can be responsible for session management, such as user session establishment, etc.; the UPF entity can be a functional entity of the user plane, mainly responsible for connecting to the external network. It should be noted that the entity in this application can also be referred to as a network element or a functional entity. For example, the AMF entity can also be referred to as an AMF network element or an AMF functional entity. For another example, the SMF entity can also be referred to as an SMF network element or an SMF functional entity, etc.

[0160] To facilitate understanding of the embodiments of the present application, the following is a brief explanation of the terms involved in the embodiments of the present application.

[0161] 1. Traditional (basic) switching

[0162] In traditional mobile communication systems, mobility management for connected UEs is controlled by network equipment during the traditional handover process. For example, the source base station sends an RRC reconfiguration message containing a handover command, instructing the UE on which target cell to handover to and how to perform the handover. Specifically, upon receiving the RRC reconfiguration message containing the handover command, the UE immediately releases the source cell, halts uplink and downlink data transmission with the source cell, and then connects to the target cell based on the handover command. Therefore, the successful transmission of the handover message is essential for successful handovers under traditional handover mechanisms.

[0163] 2. Conditional Handover (CHO)

[0164] The CHO mechanism can improve the success rate of handover. For example, when the quality of the source link is good, the source base station sends an RRC reconfiguration message containing CHO configuration information to the UE. The CHO configuration information may include the configuration information of one or more candidate cells, the execution trigger conditions or measurement configuration of the candidate cells, etc. After receiving the CHO configuration information, the UE will not immediately initiate a handover action to any candidate cell, but will continue to maintain the connection and data transmission with the source base station. After the UE finds a candidate cell that meets the execution trigger conditions among the candidate cells, it can independently determine the target cell and further initiate handover execution. Unlike CHO, under basic handover, after receiving the handover command, the UE will immediately perform handover to the target cell indicated by the handover command.

[0165] 3. Dual Active Protocol Stack (DAPS) switching

[0166] The DAPS switching mechanism can reduce the switching interruption time. Among them, the switching interruption time is the period of time during which the UE cannot transmit data with any base station during the switching. For example, the source base station indicates the target cell to the UE through an RRC reconfiguration message containing a switching command. The UE accesses the target cell according to the content contained in the switching command. During the switching execution (or access to the target cell), the UE will continue to transmit data with the source cell until the UE establishes a connection with the target cell for data transmission. Specifically, the UE can receive and send data with the source cell and the target cell at the same time in a short period of time:

[0167] The UE continues to receive downlink data from the source cell until the target cell instructs the UE to release the source cell;

[0168] The UE continues to send uplink user data to the source cell until it successfully randomly accesses the target cell.

[0169] DAPS handover places high demands on UE capabilities. From the UE's perspective, two protocol stacks are internally active during the DAPS handover process. One active protocol stack is used for transmitting and receiving user-plane data in the target cell; the other is used for transmitting and receiving user-plane data in the source cell. The source and target user-plane protocol stacks share a common PDCP entity, enabling both sides to share common reordering and deduplication functions.

[0170] 4. Random access (RA)

[0171] Random access is a necessary step for a UE to connect to a network. The RA process establishes a radio link between the terminal device and the network equipment, achieving uplink synchronization. After successful RA completion, the UE and the base station continue normal data transmission. Through random access, the UE can achieve uplink synchronization, obtain uplink resources (UL grant), and obtain a unique Cell Radio Network Temporary Identifier (C-RNTI).

[0172] RA is divided into contention-based four-step random access (4-step CBRA), non-contention-based four-step random access (4-step CFRA), contention-based two-step random access (2-step CBRA), and non-contention-based two-step random access (2-step CFRA). The following describes the 4-step CBRA and 2-step CBRA processes in detail.

[0173] Figure 4 shows a schematic flowchart of a 4-step CBRA provided in an embodiment of the present application. For ease of understanding, the terminal device is UE and the network device is gNB. As shown in Figure 4:

[0174] S410: The UE sends a random access preamble to the gNB.

[0175] Specifically, the UE sends a preamble to the gNB on a physical random access channel (PRACH) resource, such as a RACH Occasion.

[0176] For example, the gNB informs the UE of the time-frequency resource set of the PRACH in the current cell that can be used to transmit the preamble through a system message. When the UE initiates random access, it also needs to select (CBRA) or a PRACH resource specified by the base station (CFRA) to send the preamble.

[0177] S420: The gNB sends random access response information to the UE.

[0178] Specifically, after receiving the preamble from the UE, the gNB sends a random access response (RAR) to the UE. The RAR may indicate the resource location of the physical uplink shared channel (PUSCH).

[0179] The message 2 (msg2) may be referred to as message 2 below, and may include a preamble identifier, timing advance (TA) information, initial uplink grant (UL grant) information, and may also carry a temporary identifier of the UE.

[0180] S430: The UE sends a first request message to the gNB.

[0181] Specifically, the UE sends a first request information to the gNB through the PUSCH according to the resource location of the PUSCH indicated in the random access response information received from the gNB.

[0182] Optionally, the first request information includes an RRC setup request (RRC Setup Resuest) message or an RRC resume request (RRC Resume Resuest) message.

[0183] This first request message is hereinafter referred to as message 3 (msg3). The UE sends msg3 based on the UL grant information indicated in the RAR. msg3 may include Layer 2 or Layer 3 information, such as a BFR MAC CE or an RRC message. msg3 may also include UE identification information, such as the UE's C-RNTI, the UE's resume ID, or the UE's inactive RNTI (I-RNTI).

[0184] S440: The gNB sends a first response message to the UE.

[0185] Specifically, after the gNB receives the first request information from the UE, the gNB sends a first response information to the UE.

[0186] Optionally, the first response information includes one or more of the following: an RRC Setup message, an RRC Resume message, an acknowledgement (ACK) / negative acknowledgement (NACK) of the physical uplink shared channel (PUSCH) in the first request information, and a power control command, etc.

[0187] That is, since the UE carries the UE identification information in step 430, if the UE contention resolution is successful, the gNB sends a contention resolution message to the UE, which includes the UE identification information.

[0188] Figure 4 above mainly introduces the specific process of information exchange between the UE and the gNB in ​​contention-based four-step random access (4-step CBRA).

[0189] Figure 5 shows a schematic flowchart of a 2-step CBRA provided in an embodiment of the present application. For ease of understanding, the terminal device is UE and the network device is gNB. As shown in Figure 5:

[0190] S510: The UE sends a second request to the gNB.

[0191] Specifically, the UE sends a second request message to the gNB on the PRACH resource and sends uplink data to the gNB through the PUSCH.

[0192] Optionally, the second request information includes a preamble, an RRC setup request (RRC Setup Resuest) message, or an RRC resume request (RRC Resume Resuest) message.

[0193] That is, the UE sends msgA, including the 2-step RACH preamble and the data sent on the PUSCH corresponding to the preamble.

[0194] S520: The gNB sends a second response message to the UE.

[0195] Specifically, after the gNB receives the second request information from the UE, the gNB sends a second response information to the UE.

[0196] Optionally, the second response information includes one or more of the following: an RRC Setup message, an RRC Resume message, a PUSCH response ACK / NACK and a power control command in the second request information, etc.

[0197] That is, the UE receives msgB. If the conflict is resolved successfully, the UE ends the RACH process.

[0198] Specifically, msgB typically includes one or more user RARs, which are categorized as SuccessRARs and FallbackRARs. The MAC layer indicates which RAR type is being used, which can be understood as a fallback indication. A SuccessRAR with a Contention Resolution ID indicates that the gNB detected the preamble and correctly decoded the data. If the Contention Resolution ID matches the content sent by the UE in msgA, contention resolution is considered successful. A FallbackRAR, similar in format to msg2, indicates that the gNB detected the preamble but failed to decode the data.

[0199] Figure 5 above mainly introduces the specific process of information exchange between the UE and the gNB in ​​contention-based two-step random access (2-step CBRA).

[0200] 5. L1 / L2 signaling triggered mobility (L1 / L1 triggered mobility, LTM)

[0201] LTM technology can reduce the switching interruption time. Specifically, the network device sends an RRC reconfiguration message containing multiple candidate cell configuration information to the UE in advance. The candidate cell can be a cell with the same CU under the network device, or a cell with a different CU from the network device. The UE saves the configuration information of multiple candidate cells. The UE reports a layer 1 measurement report to the network device, and the network device instructs the UE to switch (cell switch) to the target cell through an L2 switching command (MAC CE). The UE switches (cell switch) to the target cell based on the stored target cell configuration information, and saves the configuration information of one or more candidate cells to support continuous switching. LTM supports early TA acquisition, RACH-less access and LTM supervision timer (also referred to as the first timer in the embodiment of the present application).

[0202] 6. Successful Handover Report (SHR)

[0203] In a scenario where mobility is successful, there may also be potential problems that lead to mobility failure. It should be noted that potential problems do not represent actual failures, but rather that during the UE handover process, the handover was not an optimal handover or encountered a near-handover failure phenomenon, so SHR recording is performed. In order to identify non-optimal (or suboptimal) handover time in a scenario where mobility is successful, the UE is introduced to record and report parameters during the handover success process to the network device, namely SHR, which is used to record mobility-related information of successful handovers with potential problems. The handover type can be traditional handover, CHO or DAPS. The source base station can optimize the UE's mobility based on the SHR information and UE context.

[0204] The network device first configures the SHR reporting conditions (also known as SHR triggering conditions) for the UE. The SHR reporting conditions are sent to the UE via an RRCReconfiguration message sent by the source base station. The UE records the SHR only if the triggering conditions are met. SHR recording is triggered when the T304 / T310 / T312 timers reach specific thresholds or when a radio link failure (RLF) occurs in the source cell during DAPS handover.

[0205] If the running time of timer T310 / T312 reaches specific threshold A, the UE considers the radio link to have failed. If the running time of timer T304 reaches specific threshold B, the UE considers the handover to have failed. Therefore, if the running time threshold of T304 / T310 / T312, which triggers the UE to record the SHR, is less than or equal to specific threshold C (failure threshold), and greater than or equal to specific threshold D, the UE considers a potential problem. Here, the value of specific threshold A is greater than the value of specific threshold B, and the value of specific threshold C is greater than the value of specific threshold D.

[0206] The definitions of the three timers T304 / T310 / T312 are as follows:

[0207] Timer T304: The duration of timer T304 indicates the duration from the time the terminal device receives the RRC reconfiguration message to the time it successfully completes random access to the target network device. The terminal device starts timer T304 when it receives the RRC reconfiguration message and stops the timer when random access is completed.

[0208] Timer T310: Also referred to as the second timer in the embodiments of the present application. The duration of timer T310 indicates the duration that the terminal device detects physical layer problems with the source network device. This problem is typically caused by the number of consecutive downlink out-of-sync indications exceeding a certain threshold. After timer T310 is started, if the radio link recovers while timer T310 is running, timer T310 is stopped.

[0209] Timer T312: Also referred to as the third timer in the present embodiment. Timer T312 is started during the execution of timer T310. The execution duration of timer T312 indicates the duration between the time when the terminal device triggers a measurement report (typically) and the time when the terminal device and the source network device regain synchronization during the execution of timer T312.

[0210] Specifically, examples of the start time, stop time, and processing after expiration of the above three timers are shown in Table 2.

[0211] Table 2 Timer functions

[0212] In general, an SHR triggered by the T304 timer usually indicates a potential failure in the UE's access to the target cell, such as a premature handover. An SHR triggered by the T310 / T312 timer or RLF occurring in the source cell during DAPS handover usually indicates a potential failure between the UE and the source cell, such as a late handover.

[0213] The SHR report includes at least one of the following information:

[0214] 1) sourceCellInfo: records the source PCell cell identifier and measurement results. The measurement results include synchronization signal and PBCH block (SSB) and channel state information reference signal (CSI-RS) measurements available at the time of handover completion. The source PCell cell's cell-level reference signal receiving power (RSRP), reference signal receiving quality (RSRQ), and signal to interference plus noise ratio (SINR), as well as beam-level RSRP and RSRQ, are recorded.

[0215] 2) targetCellInfo: records the target PCell cell identifier and measurement results. The measurement results include SSB and CSI-RS measurements based on the available SSB and CSI-RS measurements at the time of handover completion, and records the cell-level RSRP, RSRQ, and SINR of the target PCell cell, as well as the beam-level RSRP and RSRQ.

[0216] 3) shr-Cause: records the SHR triggering conditions, such as setting one or more of the following four triggering condition cause values ​​T310, T312, T304, and DAPS Failure to True to indicate.

[0217] 4) measResultNeighCells: In addition to the neighbor cell identifiers and measurement results of the source and target PCell cells, the measurement results include the SSB and CSI-RS measurements available at the time of handover completion, and record the cell-level RSRP, RSRQ, and SINR of the neighboring cells, as well as the beam-level RSRP and RSRQ.

[0218] The measurement result in the SHR report is an L3 measurement result, and the cell identification information can be one or more of the cell global identifier (CGI), physical cell identifier (PCI) and frequency, physical cell identifier (PCI), cell identifier (cell ID), non-public network identifier (NPN ID), non-terrestrial network identifier (NTN ID), cell configuration identifier, or other cell identifiers. The CGI may include a public land mobile network (PLMN ID) and a cell ID, and may also include a tracking area code.

[0219] The specific thresholds T310, T312, and T304 in SHR serve as triggering conditions for SHR. The T310 / T312 thresholds of SHR are configured by the source PCell, reflecting the physical layer desynchronization problem between the UE and the source PCell cell, and are used to optimize the RLM (radio link monitoring) / BFD (beam failure detection) configuration. The T304 threshold of SHR is configured by the target PCell, reflecting the random access problem between the UE and the target PCell, and may also reflect the mobility parameter problems of the source PCell, such as the mobility parameter problems of the target cell.

[0220] Unlike the immediate reporting mechanism of MCG failure information (after MCG RLF occurs, the UE immediately sends the MCG failure information to the SN), the SHR report reporting mechanism is delayed reporting. The UE records the SHR report. When the UE accesses the network device, the network device requests the UE to report the SHR report through the UEInformationRequest message. The UE sends the report to the network device through the UEInformationResponse message, which is used by the network device to identify mobility process problems and optimize mobility parameters.

[0221] The current SHR report covers traditional handover, CHO, and DAPS mobility scenarios, recording potential issues in successful handovers in these scenarios to identify suboptimal handover events. However, it does not support LTM scenarios. In other words, suboptimal handover events cannot be identified in LTM scenarios.

[0222] In view of this, an embodiment of the present application proposes a communication method that enables a network device to identify non-optimal handover events in an LTM scenario to adjust mobility parameters. The following describes the communication method using a terminal device and a network device as the interacting entities.

[0223] As shown in FIG6 , the method includes the following steps:

[0224] S610, the network device sends first indication information to the terminal device, and correspondingly, the terminal device receives the first indication information.

[0225] The first indication information instructs the terminal device to switch to the target cell. For example, the first indication information indicates the index of the target cell. Alternatively, the first indication information indicates a predefined number of the target cell. For example, the corresponding number of predefined cell A is 1, the corresponding number of predefined cell B is 2, and the corresponding number of predefined cell C is 3, then the first indication information indicates number 1, that is, cell A.

[0226] It should be understood that the above-mentioned cell index and predefined cell number are merely examples for identifying cells and are not limiting. Other methods for identifying or distinguishing different cells should also fall within the scope of protection of this application.

[0227] The first indication information may be sent via a media access control control element.

[0228] The target cell is one of one or more candidate cells. The configuration information of these one or more candidate cells may be pre-received by the terminal device. For example, the network device sends the configuration information of the one or more candidate cells to the terminal device, and the terminal device receives this configuration information. Optionally, the terminal device may also store this configuration information.

[0229] Optionally, the network device sends the first information to the terminal device, and correspondingly, the terminal device receives the first information.

[0230] The first information indicates a condition for triggering a successful handover report SHR, and the condition for triggering the SHR is related to at least one of a target cell, a running time of a first timer, a running time of a second timer, a running time of a third timer, a running time of a fourth timer, a running time of a fifth timer, or a fast recovery.

[0231] Each item is described in detail below.

[0232] 1. Target cell

[0233] The target cell is the handover target cell of the terminal device. For example, the terminal device hands over from cell A to cell B, where cell A is the source cell of the terminal device and cell B is the target cell of the terminal device.

[0234] The conditions for triggering SHR are related to the target cell and include: The condition for triggering SHR is that the terminal device does not have an advance TA value for the target cell. For example, the terminal device has not yet performed early TA with the target cell and therefore does not have a scheduled TA value for the target cell. Alternatively, the terminal device has performed early TA with the target cell but has not obtained a TA value.

[0235] That is to say, when the terminal device does not have the TA value of the target cell, the terminal device can record the SHR.

[0236] 2. First Timer

[0237] The first timer starts when the terminal device receives the LTM command (i.e., an example of the first indication information) and stops when the terminal device completes random access or sends the first uplink data. In other words, the running duration of the first timer is the duration from the terminal device receiving the first indication information to the terminal device completing random access or sending the first uplink data.

[0238] The LTM command is used to instruct a terminal device to perform a handover. For example, the LTM command includes the identifier or configuration identifier of the target cell. Upon receiving the LTM command, the terminal device performs a handover from the source cell to the target cell. The handover can be performed by accessing the target cell using either RACH-less or random access.

[0239] When cell switching fails, if it is RACH-less access, the terminal device believes that the network device has not received the initial uplink data during the operation of the first timer; if it is random access (RACH-based), the terminal device believes that the random access has failed (for example, the maximum number of preamble transmissions has been reached, the first timer has timed out, etc.); otherwise, the terminal device cell switching is successful.

[0240] When the first timer expires, the terminal device may initiate a reconstruction process or an LTM fast recovery process.

[0241] The conditions for triggering SHR are related to the first timer, including: the conditions for triggering SHR are: the running time of the first timer is less than the first threshold value and greater than or equal to the second threshold value, where the second threshold value is the product of the first threshold value and the first coefficient, and the first coefficient is a positive number less than 1; or, the second threshold value is a value less than the first threshold value.

[0242] The second threshold value or the first coefficient can be configurable. In one possible embodiment, the second threshold value or the first coefficient is carried in the first information. In other words, the network device indicates the first threshold value or the first coefficient to the terminal device via the first information. The above threshold value or coefficient can also be predefined. The first threshold value of the first timer is the configured duration of the first timer. When the timer running time reaches the configured duration, the timer expires.

[0243] Optionally, the condition for triggering SHR may be that the ratio of the running time of the first timer to the configured time of the first timer is greater than or equal to the threshold value A, or that the running time of the first timer is greater than or equal to the threshold value B.

[0244] For example, the second threshold value of the first timer is configured as 3 or the first coefficient is configured as 60%, the first threshold value of the first timer is configured as 5, and when the running time of the first timer is 4, the running time of the first timer meets the SHR triggering condition.

[0245] The configured duration of the first timer may also be indicated by the first information.

[0246] The first timer may also be referred to as the LTM supervisory timer. It should be understood that the name of the timer should not be limiting and may be referred to differently in future technological developments. Any timer with the same or similar functions and effects as the timer in this application should be within the scope of protection of this application.

[0247] 3. Second timer, third timer and fifth timer

[0248] The second timer starts when the terminal device detects a physical layer problem with the source cell (such as a physical layer desynchronization problem) and stops when the terminal device receives the LTM command. That is, the running duration of the second timer indicates the duration of time the terminal device detects a physical layer problem with the source network device. In other words, the running duration of the second timer is the duration from the terminal device detecting the physical layer problem with the source network device to the terminal device receiving the first indication information.

[0249] When the second timer runs and triggers the reporting of the layer 1 and / or layer 3 measurement report, the third timer starts and stops when the terminal device receives the LTM command. That is, the running duration of the third timer is the duration from the time when the measurement report is triggered by the terminal device to the time when the terminal device receives the first indication information during the running of the second timer.

[0250] The fifth timer is started when the terminal device receives or applies the radio resource control RRC reconfiguration message with synchronization function, and stops when the terminal device completes random access or when the terminal device receives a downlink physical control channel transmission after the first uplink transmission when random access is not required. That is, the duration of the fifth timer is the duration from the terminal device receiving or applying the radio resource control RRC reconfiguration message with synchronization function to the terminal device completing random access or when the terminal device receives a downlink physical control channel transmission after the first uplink transmission when random access is not required.

[0251] The second timer can refer to the above description of the T310 timer. The third timer can refer to the above description of the T312 timer. The fifth timer can refer to the above description of the T304 timer. I will not go into details here. It should be noted that the second timer can be an enhancement based on the T310 timer, or it can be a newly designed timer that is different from the T310 timer. When the second timer is a newly designed timer that is different from the T310 timer, and the second timer is configured, the terminal device can release or delete or deactivate (save the T310 / T312 timer configuration, but do not run the timer) the configured T310 timer. The third timer is the same as the T320 timer. The fifth timer is the same as the T304 timer.

[0252] The conditions for triggering SHR are related to the second timer, the third timer, or the fifth timer, and include:

[0253] The conditions for triggering SHR are: the running time of the second timer is less than the third threshold value and greater than or equal to the fourth threshold value, where the fourth threshold value is the product of the third threshold value and the second coefficient, and the second coefficient is a positive number less than 1, or the fourth threshold value is a value less than the third threshold value.

[0254] For example, the third threshold value is 4, the fourth threshold value is 2, and the running time of the second timer is 3, which is greater than the fourth threshold value and less than the third threshold value, then SHR is triggered, that is, the terminal device records SHR.

[0255] The fourth threshold value or the second coefficient may be configurable. In one possible embodiment, the fourth threshold value or the second coefficient is carried in the first information. In other words, the network device indicates the fourth threshold value or the second coefficient to the terminal device via the first information. The above threshold value or coefficient may also be predefined. The third threshold value of the second timer is the configured duration of the second timer. When the timer runs for the configured duration, the timer expires.

[0256] Optionally, the condition for triggering SHR may be that the ratio of the running time of the second timer to the configured time of the second timer is greater than or equal to the threshold value A, or that the running time of the second timer is greater than or equal to the threshold value B.

[0257] For example, the fourth threshold value of the second timer is configured as 3 or the second coefficient is configured as 60%, and the first threshold value of the second timer is configured as 5. When the running time of the second timer is 4, the running time of the first timer meets the SHR trigger condition.

[0258] Alternatively, the condition for triggering SHR is: the running time of the third timer is less than the fifth threshold value and greater than or equal to the sixth threshold value, where the sixth threshold value is the product of the fifth threshold value and the third coefficient, and the third coefficient is a positive number less than 1, or the sixth threshold value is a value less than the fifth threshold value.

[0259] The sixth threshold value or third coefficient may be configurable. In one possible embodiment, the sixth threshold value or third coefficient is carried in the first information. In other words, the network device indicates the sixth threshold value or third coefficient to the terminal device via the first information. The aforementioned threshold values ​​or coefficients may also be predefined. The fifth threshold value of the third timer is the configured duration of the first timer. When the timer reaches the configured duration, the timer expires.

[0260] Optionally, the condition for triggering SHR may be that the ratio of the running time of the third timer to the configured time of the third timer is greater than or equal to the threshold value A, or that the running time of the second timer is greater than or equal to the threshold value B.

[0261] For example, the fifth threshold value of the third timer is configured as 3 or the third coefficient is configured as 60%, the fifth threshold value of the third timer is configured as 5, and when the running time of the second timer is 4, the running time of the first timer meets the SHR trigger condition.

[0262] Alternatively, the condition for triggering SHR is: the running time of the fifth timer is less than the eighth threshold value and greater than or equal to the ninth threshold value, wherein the ninth threshold value is the product of the eighth threshold value and the fourth coefficient, and the fourth coefficient is a positive number less than 1, or the ninth threshold value is a value less than the eighth threshold value. The ninth threshold value or the fourth coefficient can be configured. In one possible embodiment, the ninth threshold value or the fourth coefficient is carried in the first information. The eighth threshold value of the third timer is the configured duration of the fifth timer. When the running time of the timer reaches the configured duration, the timer expires.

[0263] It should be understood that other methods that can determine whether the timer running time has expired should be within the scope of protection of this application, such as other multiplication, subtraction, addition or logarithm calculations or processing that can compare size relationships.

[0264] The source cell is the cell where the terminal device was located before switching.

[0265] 4. Fourth timer

[0266] The fourth timer is also called the user plane interruption time. The user plane interruption time is the duration from when the terminal device receives the LTM command to when the terminal device transmits the first uplink data or receives the first downlink data. In other words, the fourth timer runs for the duration from when the terminal device receives the first indication information to when the terminal device transmits the first uplink data or receives the first downlink data.

[0267] The condition for triggering SHR is related to the fourth timer, including: the condition for triggering SHR is: the running time of the fourth timer is greater than or equal to the seventh threshold value.

[0268] The seventh threshold value may be predefined or configured. In one possible manner, the seventh threshold value is carried in the first information.

[0269] 5. LTM Fast Recovery

[0270] LTM fast recovery is used for a terminal device to switch to a candidate cell. The candidate cell may be one or more cells. The candidate cell is different from the target cell. For example, the identifier of the candidate cell is different from the identifier of the target cell.

[0271] In one possible way, the terminal device performs cell selection, and the selected cell is an LTM candidate cell, that is, the cell selected by the terminal device is the candidate cell configured by the network device for the terminal device. For details, please refer to the above description. The terminal device applies the saved configuration information of the candidate cell to access the candidate cell in a random access or random access-free manner (the same as the above-mentioned cell switching process, cell switch). Conversely, if the cell selected is not an LTM candidate cell, the terminal device initiates an RRC reconstruction process to access the selected cell. The terminal device successfully executes the LTM fast recovery process, that is, the terminal device successfully accesses the LTM candidate cell through the LTM fast recovery process, which can also be regarded as a scenario of successful LTM cell switching (cell switch).

[0272] The conditions for triggering SHR are related to LTM fast recovery, including: the conditions for triggering SHR are: the terminal device performs LTM fast recovery or the terminal device performs LTM fast recovery successfully.

[0273] That is, when the terminal device performs LTM fast recovery, or when the terminal device performs LTM fast recovery successfully, the SHR may be recorded.

[0274] S620, the terminal device records the first report.

[0275] For example, the terminal device records the first report when it determines that the trigger condition is met. The specific judgment method can refer to the description in S610 and will not be repeated here.

[0276] S630: The terminal device sends a first report to the network device, and correspondingly, the network device receives the first report.

[0277] Optionally, the method may further include:

[0278] S640: The network device adjusts the mobility parameters according to the first report.

[0279] For example, the network side analyzes the first report and optimizes the LTM process and related parameters accordingly, such as indicating a more reasonable target cell for the terminal device to prevent the terminal device from switching to an unreasonable cell. Or, the network side instructs the terminal device to perform a cell switch at a more appropriate time to prevent the terminal device from performing the switch too early or too late, thereby reducing the probability of handover failure or radio link failure and reducing the impact of data transmission interruption time on user experience.

[0280] In this method, the network controls the recording and collection of first reports in LTM scenarios by setting trigger conditions for the first report (such as SHR). The terminal device records the first report and provides feedback to the network device. The network device can optimize mobility parameters based on the first report to reduce data transmission interruption delay during handover and reduce the probability of handover failure.

[0281] The present application also proposes a communication method, in which SHR is used as an example of the first report. As shown in FIG7 , the method may include the following steps:

[0282] S710, the terminal device records the SHR.

[0283] SHR is used to indicate information in the terminal device's execution of layer 1 / layer 2 mobility process.

[0284] For example, the SHR includes one or more of the satisfied SHR triggering conditions (or the reason for triggering the SHR record, the reason for triggering the SHR reporting), and the SHR reporting reason is related to at least one of the early TA, first timer, second timer, third timer, fourth timer or LTM fast recovery of the target cell.

[0285] The reporting reason for SHR is related to the early TA of the target cell, including: SHR reasons include no available TA value in the target cell. Furthermore, SHR reasons can be divided into two types: one is that the terminal device and the target cell did not perform early TA acquisition, and the other is that the terminal device and the target cell performed early TA acquisition but did not obtain a usable TA value. The terminal device can indicate that the SHR reason indicates no available TA value in the target cell, or it can indicate that the target cell has no available TA value, and both situations are applicable.

[0286] The SHR may include early TA information. The early TA information includes at least one of whether the terminal device has performed early TA in the target cell, the number of times the terminal device has received a PDCCH instruction indicating the target cell, the identification information of the beam attempted to perform early TA, the number of preambles sent by the attempted beam, physical random access channel PRACH resource information, and information corresponding to the candidate cell indicating that the terminal device performed early TA or information of the target cell.

[0287] Reasons for reporting an SHR related to the first timer include: the SHR reason includes: the first timer running time is less than a first threshold and greater than or equal to a second threshold, where the second threshold is the product of the first threshold and a first coefficient, and the first coefficient is a positive number less than 1; or the second threshold is a value less than the first threshold. The first threshold and / or the second threshold can be configurable.

[0288] The SHR reporting reason is related to the second timer and includes: the SHR reason includes that the running time of the second timer is less than the third threshold value and greater than or equal to the fourth threshold value,

[0289] The fourth threshold value is the product of the third threshold value and the second coefficient, the second coefficient is a positive number less than 1, or the fourth threshold value is a value less than the third threshold value.

[0290] The reason for reporting SHR is related to the third timer and includes: the running time of the third timer is less than the fifth threshold value and greater than or equal to the sixth threshold value;

[0291] The sixth threshold value is the product of the fifth threshold value and the third coefficient, the third coefficient is a positive number less than 1, or the sixth threshold value is a value less than the fifth threshold value.

[0292] The reporting reason of the SHR related to the third timer includes: the running time of the fourth timer is greater than or equal to the seventh threshold value.

[0293] The reporting reason of SHR is related to the fifth timer and includes: the running time of the fifth timer is less than the eighth threshold value and greater than or equal to the ninth threshold value, wherein the ninth threshold value is the product of the eighth threshold value and the fourth coefficient, and the fourth coefficient is a positive number less than 1, or the ninth threshold value is a value less than the eighth threshold value.

[0294] The reasons for SHR reporting include: the terminal device performs LTM fast recovery.

[0295] Among them, the target cell has no available early TA, the first timer, the second timer, the third timer, the fourth timer, the fifth timer, the user plane interruption or the LTM fast recovery. Please refer to the description in S610 and will not be repeated here.

[0296] Optionally, the SHR may also include fast recovery process information. The fast recovery process information includes information about one or more candidate cells for fast recovery, and / or the duration from the terminal device's handover failure to the successful access to one of the one or more candidate cells. The cell information may include at least one of the cell identification information, the layer 1 and / or layer 3 measurement results corresponding to the cell, and the indication information that the cell is an LTM candidate cell. The SHR may also include time information. The time information includes at least one of the user plane interruption time, the time between the terminal device receiving the candidate cell pre-configuration or receiving the first PDCCH instruction or receiving the last PDCCH instruction and the terminal device receiving the LTM command, or the running time of the first timer.

[0297] The SHR may also include cell information. This cell information includes information about at least one of the terminal device's current serving cell (i.e., source cell), the terminal device's target cell, or a neighboring cell. The cell information may include at least one of cell identification information, Layer 1 and / or Layer 3 measurement results corresponding to the cell, and an indication of whether the neighboring cell is an LTM candidate cell. An LTM candidate cell is a cell that the terminal device is allowed to access in the event of a handover failure.

[0298] The SHR may also include the access type of the terminal device, where the access type includes random access-free or random access, or the access type is random access-free, or whether the access type is random access-free.

[0299] The SHR may also include random access-based cell handover process information, where the random access-based cell handover process information indicates information about a two-step random access procedure and / or a four-step random access procedure. For the specific information type, name, or function of the information, refer to the above description of the two-step random access procedure and / or the four-step random access procedure.

[0300] It should be understood that there are three ways to indicate "yes or not" involved in this application, one way is to indicate yes (true), another way is to indicate no (false), and another way is to indicate yes or no (true or false). For example, whether the terminal device has performed early advance timing in the target cell, one way is to indicate that the terminal device has performed early advance timing in the target cell only when the terminal device has performed early advance timing in the target cell. Another way is to indicate that the terminal device has not performed early advance timing in the target cell only when the terminal device has not performed early advance timing in the target cell. Yet another way is to indicate that the terminal device has performed early advance timing in the target cell, and to indicate that the terminal device has not performed early advance timing in the target cell. Other contents indicating "yes or not" in this article can refer to the explanation here, such as "whether the neighboring area belongs to one or more candidate cells".

[0301] In addition, it should be noted that the indication of "A or B" in this application may mean indicating A or B, or indicating A, or indicating whether it is A, or indicating B, or indicating whether it is B. For example, indicating the access type of a terminal device may mean indicating random access-free or random access. It may also mean indicating random access-free. It may also mean indicating whether it is random access-free. It may also mean indicating random access. It may also mean indicating whether it is random access. "Not random access" can be understood as "is random access-free".

[0302] S720: The terminal device sends an SHR to the network device, and correspondingly, the network device receives the SHR.

[0303] Optionally, the method may further include:

[0304] S730: The network device adjusts mobility parameters according to the SHR.

[0305] Specifically, the network device adjusts the mobility parameters, which may be described in S640 and will not be described in detail.

[0306] In this method, the SHR contains relevant information about the LTM scenario, so that the UE can record potential problem information in the LTM switching success scenario. The network side can detect the occurrence of LTM non-optimal switching events, optimize relevant mobility parameters, reduce switching interruption delay, and reduce the probability of switching failure.

[0307] It should be understood that the methods proposed in the above two embodiments can be used as independent solutions or in combination with each other. For example, the network device configures the conditions for triggering the SHR for the terminal device. When the conditions for triggering the SHR are met, the terminal device records the SHR, which includes at least one item of the information in S710.

[0308] To facilitate a clear understanding of the solution of the present application, a process example applicable to the above technical solution is given below, taking the gNB-CU as an example of a network device and the UE as an example of a terminal device.

[0309] As shown in Figure 8, the process includes the following steps:

[0310] S810: The CU obtains RRC configuration information of the candidate cell.

[0311] Optionally, the gNB-CU decides to initiate an LTM (L1 / L2 triggered mobility) procedure based on a measurement report containing L3 measurement results received from the UE.

[0312] It should be noted that the candidate cell can be a cell managed by the source CU or a cell managed by another CU. In these two cases, the information sent and received by the CU is different. Specifically,

[0313] In the inter-CU case, that is, the candidate cell is a cell managed by another CU, as shown in (a) of Figure 9, the source CU (CU1) sends a handover request message to the candidate CU (CU2), indicating the candidate cell in the message. For example, the message carries the cell identifier of the candidate cell. The candidate CU (CU2) indicates the candidate cell to the candidate DUs it manages (such as DU2 and DU3). If the candidate DU accepts the request, it sends the low-layer RRC configuration of the candidate cell to the candidate CU to which the DU belongs, such as sending a handover request response, which carries the RRC configuration of the candidate cell.

[0314] If the candidate cell is not an intra-CU cell, that is, the candidate cell is a cell managed by the CU, as shown in Figure 9 (b), the CU indicates the candidate cell to the candidate DUs it manages (such as DU1, DU2, and DU3). For example, a handover request message is sent, which carries the identifier of the candidate cell. If the candidate DU accepts the request, it sends the low-layer RRC configuration information of the candidate target cell to the CU, such as a handover request response, which carries the RRC configuration of the candidate cell.

[0315] The candidate cell may be one or more of the aforementioned candidate cells.

[0316] S820. The CU sends an RRC reconfiguration message to the UE via the DU. Correspondingly, the UE receives the RRC reconfiguration message.

[0317] The RRC reconfiguration message includes L1 / L2 mobility configuration information. The L1 / L2 mobility configuration information may include configuration information of one or more candidate cells. The L1 / L2 mobility configuration information may also include whether the candidate cell is configured with RAR. The L1 / L2 mobility configuration information also includes L1 measurement control information.

[0318] In order to reduce the data interruption time between the UE and the source cell due to the CFRA between the UE and the target (candidate) cell, LTM supports the UE to perform early uplink synchronization with the candidate cell. After the UE sends a preamble to the candidate cell, the UE receives or does not receive the RAR from the source cell. Whether the UE receives the RAR is configured by the network side. For example, the network device indicates to the UE whether each candidate cell in one or more candidate cells is configured with RAR. If the candidate cell is not configured with RAR, when the LTM command (i.e., an example of the first indication information) indicates that the candidate cell is the target cell, the LTM command also indicates the TA value of the target cell.

[0319] Optionally, in S830, the UE performs early uplink synchronization and / or downlink synchronization with the candidate cell.

[0320] For example, before the UE receives the LTM command, the UE's service DU may trigger the UE to perform early TA acquisition of candidate cells. Specifically, the service DU indicates to the UE contention-free random access CFRA resources, such as SSB beam, PRACH resources and / or preamble identifier, in a PDCCH order. The service DU also indicates the ID of the candidate cell to the UE.

[0321] The UE sends a random access preamble to the candidate cell and performs a cell search to achieve early downlink synchronization with the candidate cell.

[0322] For example, the UE performs early uplink synchronization and / or downlink synchronization with the candidate cells DU2 and DU3.

[0323] S840, the DU sends an LTM command to the UE, and correspondingly, the UE receives the LTM command.

[0324] The LTM command includes the identification information of the target cell. In one possible manner, the LTM command may be sent to the UE via a MAC CE. In another possible manner, the LTM command may be other information from L1 / L2.

[0325] Optionally, before the DU sends the LTM command, the UE sends an L1 measurement result to the DU. The DU determines a target cell based on the L1 measurement result, sends an LTM command to the UE, and indicates the target cell through the LTM command.

[0326] It should be understood that the order of performing early uplink synchronization and early downlink synchronization on the UE and reporting the L1 measurement result by the UE in the embodiment of the present application is not limited.

[0327] The LTM command may further include the TA value of the target cell, and the LTM command may further include information about the beam used by the target cell for uplink / downlink data transmission.

[0328] The UE performs a cell switch according to the LTM command. Specifically, the UE applies the configuration information of the target cell. If the UE obtains the TA value of the target cell (an available TA value), it performs a random access-free (RAHC-less) to access the target cell. Otherwise, it initiates a random access to the target cell.

[0329] The UE obtains the TA value of the target cell as follows:

[0330] Method 1: If the target cell is configured with RAR, the UE receives the TA value of the target cell through RAR before the LTM command. For example, the RAR can be sent to the UE by the current DU or from the target cell, without limitation.

[0331] Method 2: If the target cell is not configured with RAR, indicate the TA value of the target cell in the LTM command.

[0332] When the UE fails to obtain the TA value of the target cell, or fails to obtain the available TA value of the target cell, the UE records a first report (e.g., an SHR). The first report may include at least one of whether the UE performs early advance timing in the target cell, the number of times the UE receives a PDCCH instruction indicating the target cell, attempted beam identification information, the number of preambles sent through the attempted beam, physical random access channel (PRACH) resource information, information corresponding to the candidate cell indicating that the UE performs early advance timing, or information about the target cell.

[0333] S850, the DU sends an LTM notification to the CU, and correspondingly, the CU receives the LTM notification.

[0334] The LTM notification is used to notify the CU of the initiation of the LTM command. Optionally, the LTM notification also includes identification information of the target cell.

[0335] S860: The UE performs LTM cell switch.

[0336] The UE switches the cell to the target cell. For example, the UE performs cell switching using either a random access-free or random access-based approach. In other words, the cell switching type includes either a random access-free or random access-based approach. For example, the UE switches from cell DU1 to cell DU2.

[0337] In a possible implementation, the UE may detect the cell handover status based on the first timer (also called LTM supervision timer) mentioned above. The cell handover status includes cell handover success or cell handover failure.

[0338] When the first timer expires, the UE may record a first report (such as an SHR), which may include the running time of the first timer.

[0339] Optionally, in S870, the UE executes the LTM fast recovery process.

[0340] If the cell handover at S860 fails or soon after the radio link failure (RLF) in the target cell, the UE can use the LTM fast recovery procedure to access a candidate cell.

[0341] In one possible manner, the UE performs cell selection, and the selected cell is the LTM candidate cell. The UE applies the saved configuration information of the candidate cell to access the candidate cell in a random access or random access-free manner (same as the above cell handover process).

[0342] In another possible manner, if the cell selected by the UE is not a candidate cell, or the cell selected by the UE is not among the candidate cells configured on the network side, the UE initiates an RRC re-establishment procedure.

[0343] It should be understood that the UE successfully executing the LTM fast recovery process, that is, the UE successfully accessing the candidate cell through the LTM fast recovery process, can also be regarded as a scenario of successful LTM cell handover.

[0344] The UE performs the LTM fast recovery process and may record a first report (such as an SHR). The first report may include information about one or more candidate cells for fast recovery and / or the time from when the UE fails to switch to when it successfully accesses a candidate cell.

[0345] Specifically, regarding the triggering of the first report and / or the content included in the first report, please refer to the above description and will not be repeated here.

[0346] In this implementation, when trigger conditions are met, the network controls the first report in the LTM scenario, such as the recording and collection of the SHR. This SHR contains relevant information from the LTM process. The terminal device records the SHR and reports it back to the network device, which then optimizes mobility parameters based on the SHR to reduce handover interruption delay and the probability of handover failure.

[0347] It can be understood that some optional features in the various embodiments of the present application may not depend on other features in certain scenarios, and may also be combined with other features in certain scenarios, without limitation.

[0348] It can also be understood that the solutions in the various embodiments of the present application can be reasonably combined and used, and the explanations or descriptions of the various terms appearing in the embodiments can be referenced or explained with each other in the various embodiments, without limitation to this.

[0349] It can also be understood that in the above-mentioned various method embodiments, the methods and operations implemented by the communication device can also be implemented by components (such as chips or circuits) that can be implemented by the communication device.

[0350] Corresponding to the methods provided in the above method embodiments, embodiments of the present application also provide corresponding apparatuses, which include modules for executing the corresponding methods in the above method embodiments. The modules may be software, hardware, or a combination of software and hardware. It is understood that the technical features described in the above method embodiments are also applicable to the following apparatus embodiments.

[0351] FIG10 is a schematic block diagram of a communication device 1000 provided in an embodiment of the present application. The device 1000 includes a transceiver unit 1010. The transceiver unit 1010 can be used to implement corresponding communication functions. The transceiver unit 1010 can also be referred to as a communication interface or a communication unit.

[0352] Optionally, the apparatus 1000 further includes a processing unit 1020. The processing unit 1020 may be configured to perform information processing.

[0353] Optionally, the device 1000 also includes a storage unit, which can be used to store instructions and / or data. The processing unit 1020 can read the instructions and / or data in the storage unit so that the device implements the actions of the communication device in the aforementioned method embodiments.

[0354] In one design, the apparatus 1000 may be the terminal device in the aforementioned embodiment, or may be a component (such as a chip) of the terminal device. The apparatus 1000 may implement steps or processes corresponding to those performed by the terminal device in the above method embodiment, wherein the transceiver unit 1010 may be used to perform the transceiver-related operations of the terminal device in the above method embodiment, and the processing unit 1020 may be used to perform the processing-related operations of the terminal device in the above method embodiment.

[0355] In a possible implementation, the transceiver unit 1010 is configured to receive first indication information and may also be configured to send a first report.

[0356] In another possible implementation, the processing unit 1020 is configured to switch cells and may also be configured to record the first report.

[0357] The device 1000 can implement the steps or processes executed by the terminal device in the method embodiment according to the embodiment of the present application. The device 1000 may include a unit for executing the method executed by the terminal device in the embodiments shown in Figures 6 to 9.

[0358] In another design, the apparatus 1000 may be the network device of the aforementioned embodiment, or a component (e.g., a chip) of the network device. The apparatus 1000 may implement steps or processes corresponding to those performed by the network device in the above method embodiment, wherein the transceiver unit 1010 may be used to perform the transceiver-related operations of the network device in the above method embodiment, and the processing unit 1020 may be used to perform the processing-related operations of the network device in the above method embodiment.

[0359] In a possible implementation, the processing unit 1020 is configured to process and send the first indication information.

[0360] In another possible implementation, the transceiver unit 1010 is configured to receive a first report.

[0361] The device 1000 can implement the steps or processes executed by the network device in the method embodiment according to the embodiment of the present application. The device 1000 may include a unit for executing the method executed by the network device in the embodiments shown in Figures 6 to 9.

[0362] A more detailed description of the device 1000 can be directly obtained by referring to the relevant description in the above method embodiment, which will not be repeated here.

[0363] It should be understood that the specific process of each unit executing the above corresponding steps has been described in detail in the above method embodiments, and for the sake of brevity, it will not be repeated here.

[0364] It should also be understood that the device 1000 here is embodied in the form of a functional unit. The term "unit" here may refer to an application specific integrated circuit (ASIC), an electronic circuit, a processor (such as a shared processor, a dedicated processor or a group processor, etc.) and a memory for executing one or more software or firmware programs, a combined logic circuit and / or other suitable components that support the described functions. In an optional example, those skilled in the art will understand that the device 1000 can be specifically a communication device (such as a terminal device, or a network device) in the above-mentioned embodiment, and can be used to execute the various processes and / or steps corresponding to the communication device in the above-mentioned method embodiments. To avoid repetition, they will not be described here.

[0365] The apparatus 1000 of each of the above-mentioned solutions has the function of implementing the corresponding steps performed by the communication device (such as a terminal device, or a network device) in the above-mentioned method. The functions can be implemented by hardware, or by hardware executing corresponding software implementations. The hardware or software includes one or more modules corresponding to the above-mentioned functions; for example, the transceiver unit can be replaced by a transceiver (for example, the sending unit in the transceiver unit can be replaced by a transmitter, and the receiving unit in the transceiver unit can be replaced by a receiver), and other units, such as the processing unit, can be replaced by a processor to respectively perform the sending and receiving operations and related processing operations in each method embodiment.

[0366] In addition, the transceiver unit 1010 may also be a transceiver circuit (for example, may include a receiving circuit and a sending circuit), and the processing unit may be a processing circuit.

[0367] It should be noted that the apparatus in FIG10 may be the device in the aforementioned embodiment, or may be a chip or chip system, such as a system on chip (SoC). The transceiver unit may be an input / output circuit or a communication interface; the processing unit may be a processor, microprocessor, or integrated circuit integrated on the chip. This is not limited here.

[0368] Figure 11 is a schematic block diagram of a communication device 1100 provided in an embodiment of the present application. The device 1100 includes a processor 1110, which is coupled to a memory 1120. Optionally, the memory 1120 is further included to store computer programs or instructions and / or data. The processor 1110 is configured to execute the computer programs or instructions stored in the memory 1120, or read data stored in the memory 1120, to perform the methods described in the above method embodiments.

[0369] Optionally, there are one or more processors 1110 .

[0370] Optionally, there are one or more memories 1120 .

[0371] Optionally, the memory 1120 is integrated with the processor 1110 or provided separately.

[0372] Optionally, as shown in Figure 11 , the apparatus 1100 further includes a transceiver 1130, which is configured to receive and / or transmit signals. For example, the processor 1110 is configured to control the transceiver 1130 to receive and / or transmit signals.

[0373] As a solution, the device 1100 is used to implement the operations performed by the communication device in the above various method embodiments.

[0374] For example, the processor 1110 is configured to execute computer programs or instructions stored in the memory 1120 to implement relevant operations of the terminal device or network device in the above various method embodiments.

[0375] During implementation, each step of the above method can be completed by an integrated logic circuit of the hardware in the processor 1110 or by instructions in the form of software. The method disclosed in conjunction with the embodiments of the present application can be directly embodied as being executed by a hardware processor, or can be executed by a combination of hardware and software modules in the processor. The software module can be located in a mature storage medium in the art, such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically erasable programmable memory, a register, etc. The storage medium is located in the memory 1120, and the processor 1110 reads the information in the memory 1120 and completes the steps of the above method in combination with its hardware. To avoid repetition, it will not be described in detail here.

[0376] It should be understood that in the embodiments of the present application, the processor may be one or more integrated circuits for executing relevant programs to perform the method embodiments of the present application.

[0377] A processor (e.g., processor 1110) may include one or more processors and be implemented as a combination of computing devices. The processor may include one or more of the following: a microprocessor, a microcontroller, a digital signal processor (DSP), a digital signal processing device (DSPD), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), a programmable logic device (PLD), gating logic, transistor logic, discrete hardware circuits, processing circuits, or other suitable hardware, firmware, and / or a combination of hardware and software to perform the various functions described in this disclosure. The processor may be a general-purpose processor or a special-purpose processor. For example, processor 1110 may be a baseband processor or a central processing unit. A baseband processor may be used to process communication protocols and communication data. A central processing unit may be used to enable the device to execute software programs and process data in the software programs. In addition, a portion of the processor may also include non-volatile random access memory. For example, the processor may also store information about the device type.

[0378] In this application, the term "program" is used broadly to refer to software. Non-limiting examples of software include program code, program, subroutine, instruction, instruction set, code, code segment, software module, application, or software application. The program can be executed in a processor and / or computer to cause the device to perform the various functions and / or processes described in this application.

[0379] The memory (e.g., memory 1120) can store data required by the processor (e.g., processor 1110) when executing software. The memory can be implemented using any suitable storage technology. For example, the memory can be any available storage medium that can be accessed by the processor and / or computer. Non-limiting examples of storage media include random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM), static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct rambus RAM (DR RAM), removable media, optical disk storage, magnetic disk storage media, magnetic storage devices, flash memory, registers, state memory, remotely mounted storage, local or remote memory components, or any other medium capable of carrying or storing software, data, or information and accessible by a processor / computer. It should be noted that the memory described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0380] The memory (e.g., memory 1120) and the processor (e.g., processor 1110) may be provided separately or integrated together. The memory may be used to connect to the processor so that the processor can read information from the memory and store and / or write information to the memory. The memory may be integrated into the processor. The memory and the processor may be provided in an integrated circuit (e.g., the integrated circuit may be provided in a UE or other network node).

[0381] 12 is a schematic block diagram of a chip system 1200 provided in an embodiment of the present application. The chip system 1200 (or also referred to as a processing system) includes a logic circuit 1210 and an input / output interface 1220 .

[0382] Logic circuit 1210 may be a processing circuit within chip system 1200. Logic circuit 1210 may be coupled to a storage unit and invoke instructions within the storage unit, enabling chip system 1200 to implement the methods and functions of various embodiments of the present application. Input / output interface 1220 may be an input / output circuit within chip system 1200, outputting information processed by chip system 1200 or inputting data or signaling information to be processed into chip system 1200 for processing.

[0383] As a solution, the chip system 1200 is used to implement the operations performed by the communication device in the above various method embodiments.

[0384] For example, the logic circuit 1210 is used to implement the processing-related operations performed by the terminal device in the above method embodiments, such as the processing-related operations performed by the terminal device in the embodiment shown in Figure 3; the input / output interface 1220 is used to implement the sending and / or receiving-related operations performed by the terminal device in the above method embodiments, such as the sending and / or receiving-related operations performed by the terminal device in the embodiment shown in Figure 3.

[0385] For another example, the logic circuit 1210 is used to implement the processing-related operations performed by the network device in the above method embodiments, such as the processing-related operations performed by the network device in the embodiment shown in Figure 3; the input / output interface 1220 is used to implement the sending and / or receiving-related operations performed by the network device in the above method embodiments, such as the sending and / or receiving-related operations performed by the network device in the embodiment shown in Figure 3.

[0386] An embodiment of the present application further provides a computer-readable storage medium storing computer instructions for implementing the methods executed by a communication device (such as a terminal device or a network device) in the above-mentioned method embodiments.

[0387] An embodiment of the present application further provides a computer program product comprising instructions, which, when executed by a computer, implement the methods performed by a communication device (such as a terminal device or a network device) in the above-mentioned method embodiments.

[0388] An embodiment of the present application also provides a communication system, which includes the terminal device and network device in the above embodiments.

[0389] The explanation of the relevant contents and beneficial effects of any of the above-mentioned devices can be referred to the corresponding method embodiments provided above, which will not be repeated here.

[0390] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the above-mentioned units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0391] The units described above as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected according to actual needs to implement the solutions provided in this application.

[0392] In addition, each functional unit in each embodiment of the present application may be integrated into one unit, each unit may exist physically separately, or two or more units may be integrated into one unit.

[0393] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0394] When software is used for implementation, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network or other programmable devices. For example, the computer can be a personal computer, a server, or a network device, etc. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from a website, computer, server or data center to another website, computer, server or data center by wired (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (such as infrared, wireless, microwave, etc.). About computer-readable storage media, reference can be made to the above description.

[0395] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A communication method, characterized in that: include: The terminal device receives first indication information sent via a media access control control element, where the first indication information indicates that the terminal device switches to a target cell, where the target cell is one of one or more candidate cells, and the configuration information of the one or more candidate cells is pre-received by the terminal device; The terminal device records a first report, where the first report is used to indicate information in a process of the terminal device performing layer 1 / layer 2 mobility; The terminal device sends the first report.

2. The method according to claim 1, characterized in that The method further comprises: The terminal device receives first information, where the first information indicates that the terminal device records the first report during a mobility process of layer 1 or layer 2 and when a trigger condition is met, wherein the first information includes the trigger condition.

3. The method according to claim 2, characterized in that The trigger condition is related to at least one of the target cell, the running time of the first timer, the running time of the second timer, the running time of the third timer, the running time of the fourth timer, the running time of the fifth timer, or fast recovery, The running time of the first timer is the time from when the terminal device receives the first indication information to when the terminal device completes random access or sends the first uplink data. The running time of the second timer is the time from when the terminal device detects a physical layer desynchronization problem with the source network device to when the terminal device receives the first indication information. The running time of the third timer is the time from when the terminal device triggers the measurement report to when the terminal device receives the first indication information during the running of the second timer, The running time of the fourth timer is the time from when the terminal device receives the first indication information to when the terminal device transmits the first uplink data or receives the first downlink data, The running duration of the fifth timer is the duration from the terminal receiving or applying a radio resource control RRC reconfiguration message with a synchronization function to the terminal device completing random access or the terminal device receiving a downlink physical control channel transmission after the first uplink transmission when random access is not required.

4. The method according to claim 3, characterized in that The trigger condition is related to the target cell, and the trigger condition is: The terminal device does not obtain an available advance timing value of the target cell, and the advance timing value is used by the terminal device to obtain uplink synchronization with the target cell to avoid random access.

5. The method according to claim 4, characterized in that The terminal device fails to obtain the advance timing value of the target cell, including: The terminal device does not perform early timing acquisition with the target cell, or, The terminal device and the target cell perform early timing acquisition and fail to obtain a usable advance timing value.

6. The method according to claim 3, characterized in that The trigger condition is related to the running time of the first timer, and the trigger condition is: The running time of the first timer is less than the first threshold value and greater than or equal to the second threshold value, The second threshold value is the product of the first threshold value and a first coefficient, and the first coefficient is a positive number less than 1; or the second threshold value is a value less than the first threshold value.

7. The method according to claim 3, characterized in that The trigger condition is related to the running time of the second timer, and the trigger condition is: The running time of the second timer is less than the third threshold value and greater than or equal to the fourth threshold value, The fourth threshold value is the product of the third threshold value and the second coefficient, the second coefficient is a positive number less than 1, or the fourth threshold value is a value less than the third threshold value.

8. The method according to claim 3, characterized in that The trigger condition is related to the running time of the third timer, and the trigger condition is: The running time of the third timer is less than the fifth threshold value and greater than or equal to the sixth threshold value, The sixth threshold value is the product of the fifth threshold value and the third coefficient, and the third coefficient is a positive number less than 1, or, The sixth threshold value is a value smaller than the fifth threshold value.

9. The method according to claim 3, characterized in that: The trigger condition is related to the running time of the fourth timer, and the trigger condition is: The running time of the fourth timer is greater than or equal to the seventh threshold value.

10. The method according to claim 3, characterized in that: The trigger condition is related to the running time of the fifth timer, and the trigger condition is: The running time of the fifth timer is less than the eighth threshold value and greater than or equal to the ninth threshold value, The ninth threshold value is the product of the eighth threshold value and a fourth coefficient, the fourth coefficient is a positive number less than 1, or the ninth threshold value is a value less than the eighth threshold value.

11. The method according to claim 3, characterized in that The trigger condition is related to the fast recovery, and the trigger condition is: The terminal device performs fast recovery based on the one or more candidate cells to access one of the candidate cells.

12. The method according to any one of claims 1 to 11, characterized in that The first report includes one or more of the following information: one or more of the triggering conditions for the first report being satisfied; Early advance timing information; Community information; Target cell access information; Quick process recovery information.

13. The method according to claim 12, characterized in that The first report includes early advance timing information, and the early advance timing information includes whether the terminal device has executed early advance timing in the target cell, the number of times the terminal device receives a downlink control channel PDCCH instruction indicating the target cell, the beam identification information attempted to execute early advance timing, the number of preamble codes sent through the attempted beam, physical random access channel PRACH resource information, information corresponding to the candidate cell indicating that the terminal device executes early advance timing, or at least one of the information of the target cell.

14. The method according to claim 12, characterized in that The first report includes quick recovery process information, which includes information of one or more candidate cells for quick recovery and / or the duration from the failure of the terminal device switching to the successful access to one of the one or more candidate cells.

15. The method according to claim 12, characterized in that The first report also includes time information, which includes the running time of the fourth timer, the time from the terminal device receiving the configuration information of the one or more candidate cells or receiving the first PDCCH instruction or receiving the last PDCCH instruction to the terminal device receiving the first indication information, or at least one of the running time of the first timer.

16. The method according to claim 12, characterized in that The first report also includes cell information, the cell information includes information of the current service cell of the terminal device, the target cell of the terminal device or at least one of the neighboring cells, the cell information includes cell identification information, layer 1 and / or layer 3 measurement results corresponding to the cell, and whether the neighboring cell belongs to the one or more candidate cells, the neighboring cells are other cells measured by the terminal device except the current service cell, and the one or more candidate cells are cells that the terminal device is allowed to access when the switching fails.

17. The method according to claim 12, characterized in that The first report also includes the target cell access information, and the target cell access information includes the access type used by the terminal device to access the target cell, and the access type is random access-free.

18. The method according to claim 17, characterized in that When the access type is random access, the target cell access information further includes information of a two-step random access process and / or a four-step random access process.

19. A communication method, characterized in that: include: The network device sends first indication information, where the first indication information indicates that the terminal device switches to a target cell, and the first indication information is sent via a media access control control element, wherein the target cell is one of one or more candidate cells, and information of the one or more candidate cells is pre-received by the terminal device; The network device receives the first report, where the first report is used to indicate information in a process in which the terminal device performs layer 1 / layer 2 mobility.

20. The method according to claim 19, characterized in that The method further comprises: The network device sends first information, where the first information instructs the terminal device to record the first report during the mobility process of layer 1 or layer 2 and when a trigger condition is met, wherein the first information includes the trigger condition.

21. The method according to claim 19 or 20, characterized in that The trigger condition is related to at least one of the target cell, the running time of the first timer, the running time of the second timer, the running time of the third timer, the running time of the fourth timer, the running time of the fifth timer, or fast recovery, The running time of the first timer is the time from when the terminal device receives the first indication information to when the terminal device completes random access or sends the first uplink data. The running time of the second timer is the time from when the terminal device detects a physical layer desynchronization problem with the source network device to when the terminal device receives the first indication information. The running time of the third timer is the time from when the terminal device triggers the measurement report to when the terminal device receives the first indication information during the running of the second timer, The running time of the fourth timer is the time from when the terminal device receives the first indication information to when the terminal device transmits the first uplink data or receives the first downlink data, The running duration of the fifth timer is the duration from the terminal receiving or applying a radio resource control RRC reconfiguration message with a synchronization function to the terminal device completing random access or the terminal device receiving a downlink physical control channel transmission after the first uplink transmission when random access is not required.

22. The method according to claim 21, characterized in that The trigger condition is related to the target cell, and the trigger condition is: The terminal device has no available advance timing value for the target cell, and the advance timing value is used by the terminal device to obtain uplink synchronization with the target cell to avoid random access.

23. The method according to claim 21, characterized in that The trigger condition is related to the running time of the first timer, and the trigger condition is: The running time of the first timer is less than the first threshold value and greater than or equal to the second threshold value, The second threshold value is the product of the first threshold value and a first coefficient, and the first coefficient is a positive number less than 1; or the second threshold value is a value less than the first threshold value.

24. The method according to claim 21, characterized in that The trigger condition is related to the running time of the second timer, and the trigger condition is: The running time of the second timer is less than the third threshold value and greater than or equal to the fourth threshold value, The fourth threshold value is the product of the third threshold value and the second coefficient, the second coefficient is a positive number less than 1, or the fourth threshold value is a value less than the third threshold value.

25. The method according to claim 21, characterized in that The trigger condition is related to the running time of the third timer, and the trigger condition is: The running time of the third timer is less than the fifth threshold value and greater than or equal to the sixth threshold value, The sixth threshold value is the product of the fifth threshold value and the third coefficient, the third coefficient is a positive number less than 1, or the sixth threshold value is a value less than the fifth threshold value.

26. The method according to claim 21, characterized in that The trigger condition is related to the running time of the fourth timer, and the trigger condition is: The running time of the fourth timer is greater than or equal to the seventh threshold value.

27. The method according to claim 21, characterized in that The trigger condition is related to the running time of the fifth timer, and the trigger condition is: The running time of the fifth timer is less than the eighth threshold value and greater than or equal to the ninth threshold value, The ninth threshold value is the product of the eighth threshold value and a fourth coefficient, the fourth coefficient is a positive number less than 1, or the ninth threshold value is a value less than the eighth threshold value.

28. The method according to claim 21, characterized in that The trigger condition is related to the fast recovery, and the trigger condition is: The terminal device performs fast recovery based on the one or more candidate cells to access one of the candidate cells.

29. The method according to any one of claims 19 to 28, characterized in that The first report includes one or more of the following information: one or more of the triggering conditions for the first report being satisfied; Early advance timing information; Community information; Target cell access information; Quick process recovery information.

30. The method according to claim 29, characterized in that The first report includes early advance timing information, and the early advance timing information includes whether the terminal device has performed early advance timing in the target cell, the number of times the terminal device receives a PDCCH instruction indicating the target cell, the beam identification information attempted to perform early advance timing, the number of preamble codes sent through the attempted beam, PRACH resource information, and information corresponding to the candidate cell indicating that the terminal device performs early advance timing or at least one of the information of the target cell.

31. The method according to claim 29, characterized in that The first report includes quick recovery process information, which includes information of one or more candidate cells for quick recovery and / or the duration from the failure of the terminal device switching to the successful access to one of the one or more candidate cells.

32. The method according to claim 29, characterized in that The first report also includes time information, which includes the running time of the fourth timer, the time between the terminal device receiving the candidate cell pre-configuration or receiving the first PDCCH instruction or receiving the last PDCCH instruction and the terminal device receiving the first indication information, or at least one of the running time of the first timer.

33. The method according to claim 29, characterized in that The first report also includes cell information, the cell information includes information of the current service cell of the terminal device, the target cell of the terminal device or at least one of the neighboring cells, the cell information includes cell identification information, layer 1 and / or layer 3 measurement results corresponding to the cell, and whether the neighboring cell belongs to the one or more candidate cells, the neighboring cells are other cells measured by the terminal device except the current service cell, and the one or more candidate cells are cells that the terminal device is allowed to access when the switching fails.

34. The method according to claim 29, characterized in that The first report also includes the target cell access information, and the target cell access information includes the access type used by the terminal device to access the target cell, and the access type is random access-free.

35. The method according to claim 34, characterized in that When the access type is random access, the target cell access information further includes information of a two-step random access process and / or a four-step random access process.

36. A communication device, characterized in that: Comprising means for executing the method as claimed in any one of claims 1 to 18.

37. A communication device, characterized in that: Comprising means for performing the method as claimed in any one of claims 19 to 35.

38. A communication system, characterized in that: Comprising a communication device as claimed in claim 34 and claim 35.

39. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program or instruction, and when the computer program or instruction is executed on a computer, the computer is caused to execute the method according to any one of claims 1 to 35.

40. A computer program product, characterized in that The computer program product comprises instructions for performing the method of any one of claims 1 to 35.

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