Communication method, device and system

Abstract

The invention provides a communication method, device and system, which can be suitable for switching scenes, such as an LTM scene. In the communication method, the terminal equipment records the related information of the switching process in the LTM scene and reports the information to the network equipment, so that the network equipment can optimize related parameters conveniently, thereby reducing the switching interruption time delay and reducing the probability of switching failure.

Description

Technical Field

[0001] This application relates to the field of communications. In particular, it relates to a communication method, apparatus, and system. Background Art

[0002] In the scenario of successful mobility, there may also be potential problems that lead to mobility failures. The potential problems do not represent real failures, but rather during the handover process, the handover is not an optimal handover or encounters a phenomenon of near handover failure. To identify non-optimal handover events in the scenario of successful mobility, a terminal device (user equipment, UE) can record and report the parameters during the successful handover process to a network device, that is, a successful handover report (SHR), to record the mobility-related information of the successful handover with potential problems. The network device can combine the SHR and the UE's context to optimize the UE's mobility. However, the current SHR mechanism does not support the layer 1 / layer 2 signaling-triggered mobility scenario (L1 / L1 triggered mobility, LTM). Summary of the Invention

[0003] This application provides a communication method, apparatus, and system that can reduce the handover interruption delay and improve the handover success rate in the LTM scenario.

[0004] In a first aspect, a communication method is provided. This method can be executed by a terminal device, or by a chip or circuit for the terminal device, or by a logic module or software that can implement all or part of the functions of the terminal device. This application does not make any limitations in this regard.

[0005] The method includes: 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, and 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 the information during the layer 1 / layer 2 mobility process of the terminal device; the terminal device sends the first report.

[0006] In this method, the information indicating the handover is sent via a media access control control element, and the terminal device can pre-receive the configuration information of the candidate cells, that is, the terminal device supports handovers in the LTM scenario. During the handover process, the terminal device can record relevant information, such as the relevant information can be some parameters during the handover process. The terminal device reports this information to the network device to facilitate the network device to adjust and optimize the LTM mobility parameters to improve the success rate of subsequent handovers.

[0007] In some implementations, the terminal device receives first information, where the first information indicates that the terminal device records the first report when it is in a mobility procedure of layer 1 or layer 2 and meets a triggering condition, and the first information includes the triggering condition.

[0008] That is, the network device configures a triggering condition for the terminal device. When the triggering condition is met, the terminal device can record relevant information. This avoids the need for the terminal device to record relevant information and report it to the network side without filtering during successful handovers, reduces the excessive recording of the first report by the terminal device, and thus reduces the storage and air interface signaling overhead of the terminal device.

[0009] In some implementations, the triggering condition is related to at least one of the target cell, the running duration of a first timer, the running duration of a second timer, the running duration of a third timer, a fourth timer, the running duration of a fifth timer, or fast recovery.

[0010] The running duration of the first timer is the duration from when the terminal device receives the first indication information to when the terminal device completes random access or sends the first uplink data.

[0011] The running duration of the second timer is the duration from when the terminal device detects a physical layer out-of-sync problem with the source network device to when the terminal device receives the first indication information.

[0012] The running duration of the third timer is the duration from when the terminal device triggers the transmission of a measurement report during the running of the second timer to when the terminal device receives the first indication information.

[0013] The running duration of the fourth timer is the duration between when the terminal device receives the first indication information and when the terminal device transmits the first uplink data or receives the first downlink data.

[0014] The running duration of the fifth timer is the duration from when the terminal receives or applies a radio resource control (RRC) reconfiguration message with a synchronization function to when the terminal device completes random access or when the terminal device receives a narrowband physical control channel transmission after the first uplink transmission in the case of random access-free.

[0015] It should be understood that the above conditions are only examples of the conditions for the terminal device to record relevant information. For example, the method of predefining that the terminal device records relevant information at a certain time point or during a certain time period can also be used in this application.

[0016] In some implementations, the triggering condition is related to the target cell, and the triggering condition is that the terminal device fails to obtain an available early timing value for the target cell, where the early timing value is used for the terminal device to obtain uplink synchronization with the target cell to avoid random access.

[0017] In some implementations, the situation that the terminal device fails to obtain the early timing value for the target cell includes: the terminal device does not perform early timing acquisition with the target cell, or the terminal device performs early timing acquisition with the target cell but fails to obtain an available early timing value.

[0018] In some implementations, the triggering condition is related to the running duration of the first timer, and the triggering condition is:

[0019] the running duration of the first timer is less than a first threshold and greater than or equal to a second threshold,

[0020] wherein, 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.

[0021] In some implementations, the triggering condition is related to the running duration of the second timer, and the triggering condition is: the running duration of the second timer is less than a third threshold and greater than or equal to a fourth threshold, where the fourth threshold is the product of the third threshold and a second coefficient, and the second coefficient is a positive number less than 1, or the fourth threshold is a value less than the third threshold.

[0022] In some implementations, the triggering condition is related to the running duration of the third timer, and the triggering condition is: the running duration of the third timer is less than a fifth threshold and greater than or equal to a sixth threshold, where the sixth threshold is the product of the fifth threshold and a third coefficient, and the third coefficient is a positive number less than 1, or the sixth threshold is a value less than the fifth threshold.

[0023] In some implementations, the triggering condition is related to the running duration of the fourth timer, and the triggering condition is: the running duration of the fourth timer is greater than or equal to a seventh threshold.

[0024] In some implementations, the triggering condition is related to the running duration of the fifth timer, and the triggering condition is that the running duration of the fifth timer is less than an eighth threshold value and greater than or equal to a ninth threshold value, where the ninth threshold value is the product of the eighth threshold value and a fourth coefficient, the fourth coefficient being a positive number less than 1, or the ninth threshold value is a value less than the eighth threshold value.

[0025] In some implementations, the triggering condition is related to the fast recovery, and the triggering condition is that the terminal device performs fast recovery based on one or more candidate cells to access one of the candidate cells.

[0026] In some implementations, the first report includes one or more of the following information: one or more of the triggering conditions satisfied for the first report; early advance timing information; cell information; target cell access information; fast process recovery information.

[0027] In this way, the first report reports both the reason for triggering the report and the relevant parameters, enabling the network side to perform root cause analysis and optimize the relevant parameters based on the first report to reduce the terminal delay of data transmission and further improve the accuracy of the network device in optimizing parameters.

[0028] In some implementations, the first report includes early advance timing information, and the early advance timing information includes at least one of whether the terminal device has performed early advance timing in the target cell, the number of times the terminal device has received a PDCCH instruction indicating the target cell, the beam identification information tried for early advance timing, the number of preambles sent through the tried beam, physical random access channel (PRACH) resource information, information corresponding to the candidate cell indicating that the terminal device performs early advance timing, or information about the target cell.

[0029] In this way, the network side optimizes the processes and parameters related to early timing based on the first report, increases the probability of avoiding random access during handover, and reduces the data transmission interruption time.

[0030] In some implementations, the first report includes fast recovery process information, and the fast recovery process information includes information about one or more candidate cells for fast recovery, and / or the duration from when the terminal device's handover fails to when it successfully accesses one of the one or more candidate cells.

[0031] In this way, the network side optimizes the LTM mobility parameters, such as the LTM target cell, based on the first report, increases the success probability of LTM handover, and reduces the data transmission interruption time.

[0032] In some implementations, the first report further includes timing information, which 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 duration from receiving the configuration information of the one or more candidate cells or receiving the first PDCCH instruction or receiving the last PDCCH instruction by the terminal device to receiving the first indication information by the terminal device.

[0033] In this manner, the network side optimizes the LTM process and related parameters based on the first report. For example, the early advance timing process and the LTM handover indication are performed at a reasonable time point / period to increase the success probability of the LTM handover without random access, so as to reduce the data transmission interruption time.

[0034] In some implementations, the first report further includes cell information, which includes information of at least one of the current serving cell of the terminal device, the target cell of the terminal device, or 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 cell is a cell other than the current serving cell measured by the terminal device, and the one or more candidate cells are cells that allow the terminal device to access when the handover fails.

[0035] In this manner, the network side optimizes the LTM mobility parameters based on the first report. For example, the LTM target cell, to increase the success probability of the LTM handover, so as to reduce the data transmission interruption time.

[0036] In some implementations, the first report further includes the target cell access information, which includes the access type used by the terminal device to access the target cell. The access type is access without random access or random access, or the access type is access without random access, or whether the access type is access without random access.

[0037] In some implementations, when the access type is random access, the target cell access information further includes information of the two-step random access process and / or the four-step random access process.

[0038] In this manner, the network side optimizes the LTM process and related parameters based on the first report, increases the success probability of the LTM handover without random access, and reduces the interruption time of the LTM handover based on random access, so as to reduce the data transmission interruption time.

[0039] In a second aspect, a communication method is provided. This method can be executed by a network device, or by a chip or circuit for the network device, or by a logic module or software that can implement all or part of the functions of the network device. This application does not make any limitations in this regard.

[0040] The method includes: the network device sends first indication information, the first indication information indicates that the terminal device switches to a target cell, 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 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 during the layer 1 / layer 2 mobility process of the terminal device.

[0041] In some implementation manners, the network device sends first information, the first information indicates that the terminal device records the first report during the layer 1 or layer 2 mobility process and when a trigger condition is met, wherein the first information includes the trigger condition.

[0042] In some implementation manners, the trigger condition is related to at least one of the target cell, the running duration of a first timer, the running duration of a second timer, the running duration of a third timer, the running duration of a fourth timer, the running duration of a fifth timer, or fast recovery.

[0043] The running duration of the first timer is the duration from when the terminal device receives the first indication information to when the terminal device completes random access or sends the first uplink data.

[0044] The running duration of the second timer is the duration from when the terminal device detects a physical layer out-of-sync problem with the source network device to when the terminal device receives the first indication information.

[0045] The running duration of the third timer is, during the running of the second timer, the duration from when the terminal device triggers the sending of a measurement report to when the terminal device receives the first indication information.

[0046] The running duration of the fourth timer is the duration between when the terminal device receives the first indication information and when the terminal device transmits the first uplink data or receives the first downlink data.

[0047] The running duration of the fifth timer is the duration from when the terminal receives or applies a radio resource control (RRC) reconfiguration message with a synchronization function to when the terminal device completes random access or when the terminal device receives a downlink physical control channel transmission after the first uplink transmission in the case of random access-free.

[0048] In some implementations, the triggering condition is related to the target cell, and the triggering condition is as follows:

[0049] The terminal device has no available advance timing value for the target cell, and the advance timing value is used for the terminal device to obtain uplink synchronization with the target cell to avoid random access.

[0050] In some implementations, the triggering condition is related to the running duration of the first timer, and the triggering condition is: the running duration of the first timer 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.

[0051] In some implementations, the triggering condition is related to the running duration of the second timer, and the triggering condition is: the running duration of the second timer is less than a third threshold and greater than or equal to a fourth threshold, where the fourth threshold is the product of the third threshold and a second coefficient, and the second coefficient is a positive number less than 1, or the fourth threshold is a value less than the third threshold.

[0052] In some implementations, the triggering condition is related to the running duration of the third timer, and the triggering condition is: the running duration of the third timer is less than a fifth threshold and greater than or equal to a sixth threshold, where the sixth threshold is the product of the fifth threshold and a third coefficient, and the third coefficient is a positive number less than 1, or the sixth threshold is a value less than the fifth threshold.

[0053] In some implementations, the triggering condition is related to the running duration of the fourth timer, and the triggering condition is: the running duration of the fourth timer is greater than or equal to a seventh threshold.

[0054] In some implementations, the triggering condition is related to the running duration of the fifth timer, and the triggering condition is: the running duration of the fifth timer is less than an eighth threshold and greater than or equal to a ninth threshold, where the ninth threshold is the product of the eighth threshold and a fourth coefficient, and the fourth coefficient is a positive number less than 1, or the ninth threshold is a value less than the eighth threshold.

[0055] In some implementations, the triggering condition is related to fast recovery, and the triggering condition is: the terminal device performs fast recovery based on the one or more candidate cells to access one of the candidate cells.

[0056] In some implementations, the first report includes one or more of the following information:

[0057] One or more of the triggering conditions of the first report that are satisfied; early timing advance information; cell information; target cell access information; fast procedure recovery information.

[0058] In some implementations, the first report includes early timing advance information, and the early timing advance information includes at least one of whether the terminal device has performed early timing advance in the target cell, the number of times the terminal device receives PDCCH instructions indicating the target cell, the beam identification information tried for performing early timing advance, the number of preambles sent through the tried beam, physical random access channel (PRACH) resource information, information corresponding to the candidate cell indicating that the terminal device performs early timing advance, or information about the target cell.

[0059] In some implementations, the first report includes fast recovery procedure information, and the fast recovery procedure information includes information about one or more candidate cells for fast recovery, and / or the duration from the terminal device's handover failure to successfully accessing one of the one or more candidate cells.

[0060] In some implementations, the first report further 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's receiving candidate cell pre-configuration or receiving the first PDCCH instruction or receiving the last PDCCH instruction and the terminal device's receiving the first indication information.

[0061] In some implementations, the first report further includes cell information, and the cell information includes information about at least one of the terminal device's current serving cell, the terminal device's target cell, or neighboring cells. The cell information includes cell identification information, layer 1 and / or layer 3 measurement results corresponding to the cell, whether the neighboring cell belongs to the one or more candidate cells, the neighboring cell being a cell other than the terminal device's currently measured serving cell, and the one or more candidate cells being cells that allow the terminal device to access when handover fails.

[0062] In some implementations, the first report further 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 being non-random access or random access, or the access type being non-random access.

[0063] In some implementations, when the access type is random access, the target cell access information further includes information on the two-step random access process and / or the four-step random access process.

[0064] It should be understood that the second aspect is the implementation on the network device side corresponding to the first aspect. The explanations, supplements, and descriptions of the beneficial effects of the first aspect are equally applicable to the second aspect and will not be elaborated here.

[0065] In a third aspect, a communication device is provided, including a transceiver unit and a processing unit. The transceiver unit is configured to receive 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, and 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 configured to record a first report, where the first report is used to indicate information during the layer 1 / layer 2 mobility process of the terminal device; the transceiver unit is further configured to send the first report.

[0066] In some implementations, the transceiver unit is further configured to receive first information, where the first information indicates that the terminal device records the first report during the layer 1 or layer 2 mobility process and when a triggering condition is met, and the first information includes the triggering condition.

[0067] In some implementations, the triggering condition is related to at least one of the target cell, the running duration of a first timer, the running duration of a second timer, the running duration of a third timer, the running duration of a fourth timer, the running duration of a fifth timer, or fast recovery.

[0068] The running duration of the first timer is the duration from when the terminal device receives the first indication information to when the terminal device completes random access or sends the first uplink data.

[0069] The running duration of the second timer is the duration from when the terminal device detects a physical layer out-of-sync problem with the source network device to when the terminal device receives the first indication information.

[0070] The running duration of the third timer is the duration from when the terminal device triggers the sending of a measurement report to when the terminal device receives the first indication information during the running of the second timer.

[0071] The running duration of the fourth timer is the duration between when the terminal device receives the first indication information and when the terminal device transmits the first uplink data or receives the first downlink data.

[0072] The running duration of the fifth timer is the duration from when the terminal receives or applies a Radio Resource Control (RRC) reconfiguration message with a synchronization function to when the terminal device completes random access or when the terminal device receives a downlink physical control channel transmission after the first uplink transmission without random access.

[0073] It should be understood that the above conditions are only examples of the conditions for the terminal device to record relevant information. For example, the predefined way for the terminal device to record relevant information at a certain time point or during a certain time period can also use this application.

[0074] In some implementation manners, the triggering condition is related to the target cell, and the triggering condition is that the terminal device has not obtained an available advance timing value for the target cell, and the advance timing value is used for the terminal device to obtain uplink synchronization with the target cell to avoid random access.

[0075] In some implementation manners, the terminal device not obtaining the advance timing value of the target cell includes that the terminal device has not performed early timing acquisition with the target cell, or the terminal device has performed early timing acquisition with the target cell but has not obtained an available advance timing value.

[0076] In some implementation manners, the triggering condition is related to the running duration of the first timer, and the triggering condition is:

[0077] The running duration of the first timer is less than a first threshold value and greater than or equal to a second threshold value,

[0078] 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.

[0079] In some implementation manners, the triggering condition is related to the running duration of the second timer, and the triggering condition is that the running duration 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.

[0080] In some implementation manners, the triggering condition is related to the running duration of the third timer, and the triggering condition is that the running duration of the third timer is less than a fifth threshold value and greater than or equal to a sixth threshold value, wherein the sixth threshold value is the product of the fifth threshold value and a 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.

[0081] In some implementations, the triggering condition is related to the running duration of the fourth timer, and the triggering condition is that the running duration of the fourth timer is greater than or equal to a seventh threshold value.

[0082] In some implementations, the triggering condition is related to the running duration of the fifth timer, and the triggering condition is that the running duration of the fifth timer is less than an eighth threshold value and greater than or equal to a ninth threshold value, where the ninth threshold value is the product of the eighth threshold value and a fourth coefficient, the fourth coefficient being a positive number less than 1, or the ninth threshold value is a value less than the eighth threshold value.

[0083] In some implementations, the triggering condition is related to the fast recovery, and the triggering condition is that the terminal device performs fast recovery based on the one or more candidate cells to access one of the candidate cells.

[0084] In some implementations, the first report includes one or more of the following information: one or more of the triggering conditions satisfied for the first report; early advance timing information; cell information; target cell access information; fast procedure recovery information.

[0085] In some implementations, the first report includes early advance timing information, and the early advance timing information includes at least one of whether the terminal device has performed early advance timing in the target cell, the number of times the terminal device has received a PDCCH instruction indicating the target cell, the beam identification information tried for performing early advance timing, the number of preambles sent through the tried beam, physical random access channel (PRACH) resource information, information corresponding to the candidate cell indicating that the terminal device performs early advance timing, or information about the target cell.

[0086] In some implementations, the first report includes fast recovery procedure information, and the fast recovery procedure information includes information about one or more candidate cells for fast recovery, and / or the duration from when the terminal device fails in handover to when it successfully accesses one of the one or more candidate cells.

[0087] In some implementations, the first report further 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 duration from when the terminal device receives the configuration information of the one or more candidate cells or receives the first PDCCH instruction or receives the last PDCCH instruction to when the terminal device receives the first indication information.

[0088] In some implementations, the first report further includes cell information, where the cell information includes information of at least one of the current serving cell of the terminal device, the target cell of the terminal device, or a neighboring cell. 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 cell is a cell other than the current serving cell measured by the terminal device, and the one or more candidate cells are cells that allow the terminal device to access when a handover fails.

[0089] In some implementations, the first report further includes the target cell access information, where the target cell access information includes the access type used by the terminal device to access the target cell. The access type is non-random access or random access, or the access type is non-random access.

[0090] In some implementations, 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.

[0091] In a fourth aspect, a communication device is provided, including a transceiver unit. The transceiver unit is configured to send first indication information, where the first indication information instructs the terminal device to switch to a target cell. The first indication information is sent via a media access control control element, where the target cell is one of the 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 further configured to receive the first report, where the first report is used to indicate information in the layer 1 / layer 2 mobility process of the terminal device.

[0092] In some implementations, the transceiver unit is further configured to send first information, where the first information instructs the terminal device to record the first report when the terminal device is in the layer 1 or layer 2 mobility process and meets a triggering condition. The first information includes the triggering condition.

[0093] In some implementations, the triggering condition is related to at least one of the target cell, the running duration of a first timer, the running duration of a second timer, the running duration of a third timer, the running duration of a fourth timer, the running duration of a fifth timer, or fast recovery.

[0094] The running duration of the first timer is the duration from when the terminal device receives the first indication information to when the terminal device completes random access or sends the first uplink data.

[0095] The running duration of the second timer is the duration from when the terminal device detects a physical layer out-of-sync problem with the source network device to when the terminal device receives the first indication information.

[0096] The running duration of the third timer is, during the running of the second timer, the duration from when the terminal device triggers the sending of a measurement report to when the terminal device receives the first indication information.

[0097] The running duration of the fourth timer is the duration between when the terminal device receives the first indication information and when the terminal device transmits the first uplink data or receives the first downlink data.

[0098] The running duration of the fifth timer is the duration from when the terminal receives or applies a radio resource control (RRC) reconfiguration message with a synchronization function to when the terminal device completes random access or when the terminal device receives a downlink physical control channel transmission after the first uplink transmission in the case of random access-free.

[0099] In some implementation manners, the triggering condition is related to the target cell, and the triggering condition is:

[0100] The terminal device has no available advance timing value for the target cell, and the advance timing value is used for the terminal device to obtain uplink synchronization with the target cell to avoid random access.

[0101] In some implementation manners, the triggering condition is related to the running duration of the first timer, and the triggering condition is: the running duration of the first timer is less than a first threshold value and greater than or equal to a second threshold value, where 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.

[0102] In some implementation manners, the triggering condition is related to the running duration of the second timer, and the triggering condition is: the running duration of the second timer is less than a third threshold value and greater than or equal to a fourth threshold value, where 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.

[0103] In some implementation manners, the triggering condition is related to the running duration of the third timer, and the triggering condition is: the running duration of the third timer is less than a fifth threshold value and greater than or equal to a sixth threshold value, where the sixth threshold value is the product of the fifth threshold value and a 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.

[0104] In some implementations, the triggering condition is related to the running duration of the fourth timer, and the triggering condition is that the running duration of the fourth timer is greater than or equal to a seventh threshold value.

[0105] In some implementations, the triggering condition is related to the running duration of the fifth timer, and the triggering condition is that the running duration of the fifth timer is less than an eighth threshold value and greater than or equal to a ninth threshold value, where the ninth threshold value is the product of the eighth threshold value and a fourth coefficient, the fourth coefficient being a positive number less than 1, or the ninth threshold value is a value less than the eighth threshold value.

[0106] In some implementations, the triggering condition is related to fast recovery, and the triggering condition is that the terminal device performs fast recovery based on the one or more candidate cells to access one of the candidate cells.

[0107] In some implementations, the first report includes one or more of the following information: one or more of the triggering conditions satisfied in the first report; early advance timing information; cell information; target cell access information; fast procedure recovery information.

[0108] In some implementations, the first report includes early advance timing information, and the early advance timing information includes at least one of whether the terminal device has performed early advance timing in the target cell, the number of times the terminal device has received a PDCCH instruction indicating the target cell, the beam identification information tried for early advance timing, the number of preambles sent through the tried beam, physical random access channel (PRACH) resource information, information corresponding to the candidate cell indicating that the terminal device performs early advance timing, or information about the target cell.

[0109] In some implementations, the first report includes fast recovery procedure information, and the fast recovery procedure information includes information about one or more candidate cells for fast recovery, and / or the duration from when the terminal device fails to switch to successfully accessing one of the one or more candidate cells.

[0110] In some implementations, the first report further 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 when the terminal device receives candidate cell pre-configuration or receives the first PDCCH instruction or receives the last PDCCH instruction and when the terminal device receives the first indication information.

[0111] In some implementations, the first report further includes cell information, where the cell information includes information of at least one of the current serving cell of the terminal device, the target cell of the terminal device, or a neighboring cell. 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 cell is a cell other than the current serving cell measured by the terminal device, and the one or more candidate cells are cells that allow the terminal device to access when a handover fails.

[0112] In some implementations, the first report further includes the target cell access information, where the target cell access information includes the access type used by the terminal device to access the target cell. The access type is non-random access or random access, or the access type is non-random access.

[0113] In some implementations, 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.

[0114] In a fifth aspect, the present application provides a communication device, including an interface circuit and a processor. The interface circuit is configured to implement the functions of the transceiver module in the third aspect, and the processor is configured to implement the functions of the processing module in the third aspect.

[0115] In a sixth aspect, the present application provides a communication device, including an interface circuit and a processor. The interface circuit is configured to implement the functions of the transceiver module in the fourth aspect, and the processor is configured to implement the functions of the processing module in the sixth aspect.

[0116] In a seventh aspect, the present application provides a computer-readable medium, which stores program code for a terminal device to execute. The program code includes instructions for executing the method in the first aspect, or any possible manner in the first aspect, or all possible manners in the first aspect.

[0117] In an eighth aspect, an embodiment of the present application provides a computer-readable medium, which stores program code for a network device to execute. The program code includes instructions for executing the method in 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.

[0118] In a ninth aspect, there is provided a computer program product storing computer-readable instructions, which, when run on a computer, cause the computer to execute the method of the first aspect, or any possible manner in the first aspect, or all possible manners in the first aspect.

[0119] In a tenth aspect, there is provided a computer program product storing computer-readable instructions, which, when run on a computer, cause the computer to execute the method of the second aspect, or any possible manner in the second aspect, or all possible manners in the second aspect.

[0120] In an eleventh aspect, there is provided a communication system, which includes a device having the function of implementing the method of the 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 designs.

[0121] In a twelfth aspect, there is provided a processor for coupling with a memory and executing the method of the first aspect, or any possible manner in the first aspect, or all possible manners in the first aspect.

[0122] In a thirteenth aspect, there is provided a processor for coupling with a memory and executing the method of the second aspect, or any possible manner in the second aspect, or all possible manners in the second aspect.

[0123] In a fourteenth aspect, there is provided a chip system, which includes a processor and may further include a memory, for executing a computer program or instructions stored in the memory, so that the chip system implements the method in any one of the foregoing first aspect or second aspect, and any possible implementation manner of any aspect. The chip system may be composed of chips or may include chips and other discrete devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0124] Figure 1 is a schematic diagram of a wireless communication system applicable to an embodiment of the present application.

[0125] Figure 2 is a schematic diagram of a protocol stack applicable to an embodiment of the present application.

[0126] Figure 3 is a schematic diagram of an ORAN system applicable to an embodiment of the present application.

[0127] Figure 4 is a schematic flowchart of a contention-based four-step random access provided by an embodiment of the present application.

[0128] Figure 5 It is a schematic flowchart of a contention-based two-step random access provided by an embodiment of the present application.

[0129] Figure 6 It is a schematic diagram of a communication method provided by an embodiment of the present application.

[0130] Figure 7 It is a schematic diagram of another communication method provided by an embodiment of the present application.

[0131] Figure 8 It is a schematic flowchart of a communication method provided by an embodiment of the present application.

[0132] Figure 9 It is a schematic diagram of two handover processes provided by an embodiment of the present application.

[0133] Figure 10 It shows a schematic block diagram of a communication device provided by an embodiment of the present application.

[0134] Figure 11 It shows a schematic structural diagram of a communication device provided by an embodiment of the present application.

[0135] Figure 12 It shows a schematic diagram of a chip system provided by an embodiment of the present application. Detailed implementation manners

[0136] Next, the technical solutions in the embodiments of the present application will be described with reference to the accompanying drawings.

[0137] The technical solutions provided by the present application can be applied to various communication systems, such as: the fifth generation (5G) or new radio (NR) system, long term evolution (LTE) system, LTE frequency division duplex (FDD) system, LTE time division duplex (TDD) system, etc. The technical solutions provided by the present application can also be applied to future communication systems, such as the sixth generation mobile communication system. The technical solutions provided by the present 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.

[0138] The terminal devices in the embodiments of this application include various devices with wireless communication functions, which can be used to connect people, objects, machines, etc. The terminal devices can be widely applied to 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 wearables, smart transportation, smart city drones, robots, remote sensing, passive sensing, positioning, navigation and tracking, autonomous delivery and other scenarios. 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 can be a user equipment (UE), terminal, fixed device, mobile station device or mobile device, subscriber unit, handheld device, in-vehicle device, wearable device, cellular phone, smart phone, SIP phone, wireless data card, personal digital assistant (PDA), computer, tablet computer, laptop computer, wireless modem, handset, laptop computer, computer with wireless transceiver function, smart book, vehicle, satellite, global positioning system (GPS) device, target tracking device, aircraft (such as drones, helicopters, multi-rotor helicopters, quadcopters, or airplanes, etc.), ship, remote control device, smart home device, industrial device, or a device built into the above devices (such as a communication module, modem or chip in the above devices), or other processing devices connected to a wireless modem. For the convenience of description, the terminal device will be described below by taking the terminal or UE as an example.

[0139] It should be understood that in some scenarios, the UE can also be used as a base station. For example, the UE can act as a scheduling entity that provides sidelink signals between UEs in scenarios such as V2X, D2D, or P2P.

[0140] In the embodiments of the present application, the device for implementing the functions of the terminal device may be the terminal device itself, or a device capable of supporting the terminal device to implement such functions, such as a chip system or a chip. This device may be installed in the terminal device. In the embodiments of the present application, the chip system may be composed of chips, or may include chips and other discrete devices.

[0141] The network device in the embodiments of the present application may be a device for communicating with the terminal device. This network device 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 the terminal device to a wireless network. The base station may generally cover various names as follows, or be replaced with the following names, such as: Node B, evolved Node B (eNB), next generation Node B (gNB), relay station, access point, transmitting and receiving point (TRP), transmitting point (TP), master station, slave station, multi-mode radio (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 may 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 may also refer to a communication module, a modem or a chip disposed in the foregoing device or apparatus. The base station may also be a mobile switching center and a device that undertakes the base station function in D2D, V2X, M2M communications, a network-side device in a 6G network, a device that undertakes the base station function in a future communication system, etc. The base station may support networks with the same or different access technologies. The embodiments of the present application do not limit the specific technologies and specific device forms adopted by the network device.

[0142] The base station may be fixed or mobile. For example, a helicopter or a drone may be configured to act as a mobile base station, and one or more cells may move according to the position of the mobile base station. In other examples, a helicopter or a drone may be configured to be a device for communicating with another base station.

[0143] In the embodiments of the present application, the device for implementing the functions of a network device may be a terminal device, or a device capable of supporting the network device to implement such functions, such as a chip system or a chip, and this device may be installed in the network device. In the embodiments of the present application, the chip system may be composed of chips, or may include chips and other discrete devices.

[0144] The network device and the terminal device may be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; they may also be deployed on water; they may also be deployed on airplanes, balloons, and satellites in the air. In the embodiments of the present application, the scenarios where the network device and the terminal device are located are not limited.

[0145] First, a network architecture applicable to the embodiments of the present application is briefly introduced as follows.

[0146] Figure 1 is a schematic diagram of a wireless communication system 100 applicable to the embodiments of the present application. As Figure 1 shown, the wireless communication system 100 may include at least one network device, such as Figure 1 the network device 110a shown, and the wireless communication system 100 may also include at least one terminal device, such as Figure 1 the terminal devices 120a and 120b shown. 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. The terminal devices may also communicate with each other. For example, the terminal devices may directly communicate with each other. For another example, the terminal devices may communicate with each other through other communication devices, such as a network device or other terminal devices.

[0147] Among them, when the network device and the terminal device communicate, the network device may manage one or more cells, and there may be an integer number of terminal devices in one cell. Optionally, the network device 110a and the terminal device 120a form a single-cell communication system. Without loss of generality, the cell is referred to as cell #1. The network device 110a may be the network device in cell #1, or the network device 110a may serve the terminal device (such as the terminal device 120a) in cell #1.

[0148] It should be noted that a cell can be understood as the area within the wireless signal coverage of the network device.

[0149] It should be understood that Figure 1 for the sake of easy understanding, this is a simplified schematic diagram. The wireless communication system 100 may also include other network devices or other terminal devices, Figure 1 which are not shown in the figure. The embodiments of the present application may be applicable to any communication scenario where a sending-end device and a receiving-end device communicate.

[0150] 1) The terminal 120 can also be referred to as a terminal device, user equipment (UE), mobile station, mobile terminal, etc. The terminal can be widely applied in various scenarios, such as 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, remote medical treatment, smart grid, smart furniture, smart office, smart wearables, smart transportation, smart city, etc. The terminal can 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.

[0151] 2) The RAN node 110, sometimes also referred to as an access network device, RAN entity or access node, etc., constitutes a part of the communication system to help the terminal achieve wireless access. The multiple RAN nodes 110 in the communication system 1000 can be of the same type of nodes or different types of nodes. In some scenarios, the roles of the RAN node 110 and the terminal 120 are relative. For example, Figure 1 The network element 120i can be a helicopter or a drone, which can be configured as a mobile base station. For the terminal 120j accessing 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 both referred to as communication devices. For example, Figure 1 the network elements 110a and 110b in the figure 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.

[0152] In a possible scenario, the RAN node can 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 6th generation (6G) mobile communication system, a base station in a future mobile communication system, or an access node in a WiFi system, etc. The RAN node can be a macro base station (such as Figure 1 110a in the figure), a micro base station or an indoor station (such asFigure 1 Among them, 110b), a relay node or a donor node, or a radio controller in a CRAN scenario. Optionally, the RAN node can also be a server, a wearable device, a vehicle or an in-vehicle device, etc. For example, the access network device in vehicle to everything (V2X) technology can be a road side unit (RSU).

[0153] In another possible scenario, multiple RAN nodes cooperate to assist the terminal in achieving wireless access, and different RAN nodes respectively implement some functions of the base station. For example, the RAN node can be a central unit (CU), a distributed unit (DU), a CU-control plane (CP), a CU-user plane (UP), or a radio unit (RU), etc. The CU and the DU can be set separately, or can also be included in the same network element, such as a baseband unit (BBU). The CU node and the DU node split the protocol layer of the gNB, and the functions of some protocol layers are centrally controlled by the CU, and the functions of the remaining part or all protocol layers are distributed in the DU, and the DU is centrally controlled by the CU. As an implementation method, as Figure 2 shown, the CU deploys the radio resource control (RRC) layer, the packet data convergence protocol (PDCP) layer, and the service data adaptation protocol (SDAP) layer in the protocol stack; the DU deploys 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 can be understood that the above function splitting is only an example and does not constitute a limitation on the CU and the DU. The RU can be included in a radio frequency device or a radio frequency unit, such as included in a remote radio unit (RRU), an active antenna unit (AAU), or a remote radio head (RRH).

[0154] In different systems, the 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, the CU may also be referred to as O-CU (Open CU), the DU may also be referred to as O-DU, the CU-CP may also be referred to as O-CU-CP, the CU-UP may also be referred to as O-CU-UP, and the RU may also be referred to as O-RU. For the convenience of description, in this application, the CU, CU-CP, CU-UP, DU, and RU are used as examples for description. Any unit among the CU (or CU-CP, CU-UP), DU, and RU in this application may be implemented by a software module, a hardware module, or a combination of a software module and a hardware module. For the specific protocol layer functions, please refer to Table 1:

[0155] Table 1 Correspondence between Access Network Devices (Network Element Modules) of ORAN and the Protocol Layer Functions They Can Implement

[0156]

[0157]

[0158] Exemplarily, Figure 3 FIG. is a schematic diagram of an ORAN system, and the ORAN system may include one or more CUs, DUs, and RUs.

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

[0160] To facilitate the understanding of the embodiments of this application, the terms involved in the embodiments of this application will be briefly described below.

[0161] 1. Traditional (basic) handover

[0162] In a mobile communication system, in the traditional handover process, the mobility management of a connected UE is controlled by network devices. For example, the source base station instructs the UE to which target cell to hand over and how to perform the handover by sending an RRC reconfiguration message containing a handover command. Specifically, after receiving the RRC reconfiguration message containing the handover command, the UE immediately releases the source cell, stops the uplink / downlink data transmission with the source cell, and accesses the target cell according to the content contained in the handover command. Therefore, the successful transmission of the handover message is a necessary condition for ensuring a successful handover under the traditional handover mechanism.

[0163] 2. Conditional Handover (CHO)

[0164] The CHO mechanism can improve the handover success rate. For example, when the source link quality 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 of the candidate cells, or measurement configurations, etc. After receiving the CHO configuration information, the UE does not immediately initiate a handover execution action to any candidate cell, but continues 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 a handover execution. Different from CHO, in basic handover, after receiving the handover command, the UE will immediately perform a handover to the target cell indicated by the handover command.

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

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

[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 requirements on UE capabilities. From the UE's perspective, during a DAPS handover, there are two active protocol stacks internally. One active protocol stack is used for the transmission and reception of user-plane data in the target cell; the other active protocol stack is used for the transmission and reception of user-plane data in the source cell. The PDCP entity is shared between the user-plane protocol stack on the source side and the user-plane protocol stack on the target side, enabling the source side and the target side to have a common reordering and deduplication function.

[0170] 4. Random Access (RA)

[0171] Random access is a necessary step for a UE to connect to the network. The terminal device and the network device establish a wireless link through the RA process to achieve uplink synchronization. After the RA is successfully completed, normal data transmission occurs between the UE and the base station. Through random access, the UE can achieve the following purposes: obtain uplink synchronization, acquire uplink resources (UL grant), and obtain a unique Cell Radio Network Temporary Identifier (C-RNTI).

[0172] Among them, RA is divided into 4-step contention based random access (4-step CBRA), 4-step contention free random access (4-step CFRA), 2-step contention based random access (2-step CBRA), and 2-step contention free random access (2-step CFRA). The processes of 4-step CBRA and 2-step CBRA are described in detail below.

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

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

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

[0176] Exemplarily, the gNB informs the UE of the set of time-frequency resources of the PRACH available for transmitting the preamble in the current cell through system information. When the UE initiates random access, it also needs to select (CBRA) or be specified by the base station (CFRA) the PRACH resource to send the preamble.

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

[0178] Specifically, after the gNB receives the preamble from the UE, the gNB sends random access response (RAR) information to the UE. Among them, the RAR can indicate the resource location of the physical uplink shared channel (PUSCH).

[0179] The following can be abbreviated as message 2 (msg2), which can include a preamble identifier, timing advance (TA) information, initial uplink grant (UL grant) information, and can 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 message 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 message includes an RRC setup request (RRC Setup Resuest) message or an RRC resume request (RRC Resume Resuest) message.

[0183] The first request message is hereinafter abbreviated as message 3 (msg3). That is, the UE sends msg3 according to the UL grant information indicated in the RAR. Msg3 can include L2 or L3 information, such as a BFR MAC CE or an RRC message. Msg3 can include UE identification information, such as the C-RNTI information of the UE, the resume identifier (Resume ID) of the UE, or the inactive identifier (Inactive RNTI, I-RNTI).

[0184] S440, the gNB sends the first response message to the UE.

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

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

[0187] That is, since the UE will carry UE identification information in step 430, if the UE's contention resolution is successful, the gNB sends a contention resolution message to the UE, which contains the UE identification information.

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

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

[0190] S510, the UE sends a second request message to the gNB.

[0191] Specifically, the UE sends the 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 message includes a preamble, an RRC Setup Request message, or an RRC Resume Request 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 the second response information to the UE.

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

[0197] That is, the UE receives msgB. If the conflict resolution is successful, the UE ends the RACH procedure.

[0198] Specifically, msgB usually includes one or more RARs for users. The RAR is divided into SuccessRAR and FallbackRAR. The MAC layer indicates which type of RAR it is. It can be understood that this indication can be called the fallback indication. SuccessRAR carries the Contention Resolution ID, indicating that the gNB has detected the preamble and decoded the data correctly. If the CR ID is the same as the content sent by the UE in msgA, it is considered that the conflict resolution is successful. And FallbackRAR is similar in format to msg2, indicating that the gNB has detected the preamble but has not decoded the data correctly.

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

[0200] 5. L1 / L2 Signaling Triggered Mobility (LTM)

[0201] The LTM technology can reduce the handover interruption time. Specifically, the network device pre-sends an RRC reconfiguration message containing the configuration information of multiple candidate cells to the UE. The candidate cells can be cells of the same CU as the network device or cells of 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. The network device instructs the UE to switch (cell switch) to the target cell through an L2 handover command (MAC CE). The UE switches (cell switch) to the target cell based on the stored configuration information of the target cell and saves the configuration information of one or more candidate cells to support continuous handover. LTM supports early TA acquisition, RACH-less access, and the LTM supervision timer (also referred to as the first timer in the embodiments of this application).

[0202] 6. Successful Handover Report (SHR)

[0203] In the scenario of successful mobility, there may also be potential problems that could lead to mobility failures. It should be noted that potential problems do not represent real failures, but rather during the UE handover process, the handover is not an optimal handover or there is a phenomenon close to handover failure. Therefore, SHR records are made. To identify non-optimal (or sub-optimal) handover times in the successful mobility scenario, 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 by combining SHR information and UE context.

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

[0205] When the running time of the timers T310 / T312 reaches a specific threshold A, the UE considers a radio link failure. When the running time of the timer T304 reaches a specific threshold B, the UE considers the handover a failure. Therefore, the running time thresholds of T304 / T310 / T312 that trigger the UE to record SHR are less than or equal to a specific threshold C, i.e., the failure threshold, and greater than or equal to a specific threshold D, the UE will consider there to be potential problems. Here, the value of the specific threshold A is greater than the value of the specific threshold B, and the value of the specific threshold C is greater than the value of the specific threshold D.

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

[0207] Timer T304: The running duration of timer T304 indicates the duration from when the terminal device receives the RRC reconfiguration message to successfully completing 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 this application. The running duration of timer T310 indicates the duration during which the terminal device detects physical layer problems with the source network device. This problem is usually that the number of consecutive received downlink out-of-sync indications exceeds a certain threshold. After starting timer T310, during the running period of this timer T310, if the radio link is restored, then this timer T310 stops.

[0209] Timer T312: Also referred to as the third timer in the embodiments of this application. Timer T312 is started during the running period of timer T310. The running duration of timer T312 indicates the duration between when the terminal device triggers a measurement report (usually) and when the terminal device and the source network device resume synchronization during the running period of timer T312.

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

[0211] Table 2 Timer Functions

[0212]

[0213]

[0214] Overall, the SHR triggered by timer T304 usually points to potential failures during the UE's access process to the target cell, such as those caused by premature handover; the SHR triggered by timer T310 / T312 or RLF that occurs in the source cell during DAPS handover usually points to potential failures between the UE and the source cell, such as those caused by late handover.

[0215] The SHR report includes at least one of the following information:

[0216] 1) sourceCellInfo: Records the source PCell cell identifier and measurement results. The measurement results include measurements based on the synchronization signal and PBCH block (SSB) and channel state information reference signal (CSI-RS) available at the handover completion moment, records the cell-level reference signal receiving power (RSRP), reference signal receiving quality (RSRQ), and signal to interference plus noise ratio (SINR) of the source PCell cell, as well as the beam-level RSRP and RSRQ.

[0217] 2) targetCellInfo: Records the target PCell cell identifier and measurement results. The measurement results include measurements based on the SSB and CSI-RS available at the handover completion moment, records the cell-level RSRP, RSRQ, and SINR of the target PCell cell, as well as the beam-level RSRP and RSRQ;

[0218] 3) shr-Cause: Records the SHR trigger conditions, such as indicating by setting one or more of the following four trigger condition cause values T310, T312, T304, DAPS failure (DAPSFailure) to True.

[0219] 4) measResultNeighCells: In addition to the neighbor cell identifiers and measurement results of the source cell and the target PCell cell, the measurement results include measurements based on the SSB and CSI-RS available at the handover completion moment, records the cell-level RSRP, RSRQ, and SINR of the neighboring cells, as well as the beam-level RSRP and RSRQ.

[0220] Among them, the measurement result in the SHR report is the L3 measurement result. The cell identification information can be one or more of the cell global identifier (CGI), physical cell identifier (PCI) and frequency point, physical cell identifier (PCI), cell identifier (cellID), non-public network identifier (NPN ID), non-terrestrial network identifier (NTN ID), cell configuration identifier, or other cell identification. The CGI can include the public land mobile network (PLMN ID) and cellID, and can also include the tracking area code.

[0221] The specific thresholds of T310, T312, and T304 in the SHR are used as the triggering conditions for the SHR. Among them, the T310 / T312 thresholds of the SHR are configured by the source PCell, reflecting the physical layer out-of-synchronization problem between the UE and the source PCell to optimize the RLM (radio link monitoring) / BFD (beam failure detection) configuration. The T304 threshold of the 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 problem of the source PCell, such as the mobility parameter problem of the target cell, etc.

[0222] Different from the immediate reporting mechanism of the MCG failure information (after the MCG RLF occurs, the UE immediately sends the MCG failure information to the SN), the reporting mechanism of the SHR report 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, and the UE sends the report to the network device through the UEInformationResponse message, which is used for the network device to identify the mobility process problem and optimize the mobility parameters.

[0223] The current SHR report covers traditional handover, CHO, and DAPS mobility scenarios, records potential problems in successful handovers in the above scenarios to identify non-optimal handover events, but does not support the LTM scenario. That is to say, in the LTM scenario, non-optimal handover events cannot be identified.

[0224] In view of this, an embodiment of the present application provides a communication method, which enables a network device to identify a non-optimal handover event in an LTM scenario to adjust mobility parameters. The following describes this communication method with the terminal device and the network device as the interaction entities.

[0225] As Figure 6 shown, the method includes the following steps:

[0226] S610, the network device sends first indication information to the terminal device, and correspondingly, the terminal device receives the first indication information.

[0227] The first indication information instructs the terminal device to hand over to the target cell. Exemplarily, 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, if predefined cell A corresponds to number 1, predefined cell B corresponds to number 2, and predefined cell C corresponds to number 3, then the first indication information indicating number 1 indicates cell A.

[0228] It should be understood that the above index of the cell and the predefined number of the cell are only examples for identifying the cell rather than limitations, and other ways that can identify or distinguish different cells should also be within the protection scope of the present application.

[0229] The first indication information may be sent via a media access control control element.

[0230] The target cell is one of one or more candidate cells, and 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 these one or more candidate cells to the terminal device, and the terminal device receives these configuration information. Optionally, the terminal device may also store these configuration information.

[0231] Optionally, the network device sends first information to the terminal device, and correspondingly, the terminal device receives the first information.

[0232] Wherein, the first information indicates the condition for triggering a successful handover report (SHR). The condition for triggering the SHR is related to at least one of the target cell, 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, or fast recovery.

[0233] The following elaborates on each item in detail.

[0234] 1. Target cell

[0235] The target cell is the handover target cell of the terminal device. By way of example, the terminal device hands over from cell A to cell B. Cell A is the source cell of the terminal device, and cell B is the target cell of the terminal device.

[0236] The condition for triggering the SHR is related to the target cell and includes: The condition for triggering the SHR is that the terminal device has no timing advance (TA) value of the target cell. For example, the terminal device has not performed early TA with the target cell, so there is no TA value of the target cell. Or, the terminal device has performed early TA with the target cell, but has not obtained the TA value.

[0237] That is to say, when the terminal device has no TA value of the target cell, the terminal device can record the SHR.

[0238] 2. First timer

[0239] 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. That is, the running duration of the first timer is the duration from when the terminal device receives the first indication information to when the terminal device completes random access or sends the first uplink data.

[0240] The LTM command is used to instruct the terminal device to perform a handover. By way of example, the LTM command includes the identifier or configuration identifier of the target cell. After receiving the LTM command, the terminal device performs a handover from the source cell to the target cell. The handover method can be RACH-less access to the target cell or random access-based access to the target cell.

[0241] When the cell handover fails, if it is RACH-less access, the terminal device considers that the network device has not received the initial uplink data during the running of the first timer; if it is random access (RACH-based), the terminal device considers that the random access fails (for example, reaching the maximum preamble transmission times, the first timer expires, etc.); otherwise, the terminal device's cell handover is successful.

[0242] When the first timer expires, the terminal device can initiate a reconstruction process or a fast LTM recovery process.

[0243] The condition for triggering the SHR is related to the first timer and includes: The condition for triggering the SHR is that the running duration 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.

[0244] The second threshold or the first coefficient may be configured. In one possible way, the second threshold or the first coefficient is carried in the first information. In other words, the network device indicates the first threshold or the first coefficient to the terminal device through the first information. The above-mentioned threshold or coefficient may also be predefined. Among them, the first threshold of the first timer is the configured duration of the first timer. When the running duration of the timer reaches the configured duration, that is, the timer expires.

[0245] Optionally, the condition for triggering the SHR may be that the ratio of the running duration of the first timer to the configured duration of the first timer is greater than or equal to threshold A, or the running duration of the first timer is greater than or equal to threshold B.

[0246] For example, the second threshold of the first timer is configured to be 3 or the first coefficient is configured to be 60%, and the first threshold of the first timer is configured to be 5. When the running duration of the first timer is 4, the running duration of the first timer meets the SHR trigger condition.

[0247] The configured duration of the first timer may also be indicated through the first information.

[0248] The first timer may also be referred to as the LTM supervision timer. It should be understood that the name of the timer should not cause any limitation. There may be other names in future technological developments. Timers with the same or similar functions and roles as the timer in this application should be within the protection scope of this application.

[0249] 3. The second timer, the third timer, and the fifth timer

[0250] The second timer is started when the terminal device detects a physical layer problem (such as a physical layer out-of-sync problem) in the source cell and stops when the terminal device receives the LTM command. That is, the running duration of the second timer indicates the duration during which the terminal device detects a physical layer problem with the source network device. Or rather, the running duration of the second timer is the duration from when the terminal device detects a physical layer problem with the source network device to when the terminal device receives the first indication information.

[0251] When the second timer is running and triggers the reporting of layer 1 and / or layer 3 measurement reports, the third timer is started and stops when the terminal device receives the LTM command. That is, the running duration of the third timer is the duration 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 of the second timer.

[0252] The fifth timer starts when the terminal device receives or applies a Radio Resource Control (RRC) reconfiguration message with a 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 in the case of random access exemption. That is, the duration of the fifth timer is the time from when the terminal device receives or applies an RRC reconfiguration message with a synchronization function to when the terminal device completes random access or when the terminal device receives a downlink physical control channel transmission after the first uplink transmission in the case of random access exemption.

[0253] The second timer can refer to the description of the T310 timer in the previous text. The third timer can refer to the description of the T312 timer in the previous text. The fifth timer can refer to the description of the T304 timer in the previous text. Details are not repeated here. It should be noted that the second timer can be an enhancement based on the T310 timer or a newly designed timer different from the T310 timer. When the second timer is a newly designed timer different from the T310 timer and 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 same applies to the third timer and the T320 timer. The same applies to the fifth timer and the T304 timer.

[0254] The conditions for triggering SHR are related to the second timer, the third timer, or the fifth timer, including:

[0255] The condition for triggering SHR is that the running duration of the second timer is less than the third threshold and greater than or equal to the fourth threshold, where the fourth threshold is the product of the third threshold and the second coefficient, and the second coefficient is a positive number less than 1, or the fourth threshold is a value less than the third threshold.

[0256] For example, if the third threshold is 4, the fourth threshold is 2, and the running duration of the second timer is 3, which is greater than the fourth threshold and less than the third threshold, then SHR is triggered, that is, the terminal device records SHR.

[0257] The fourth threshold or the second coefficient can be configured. In one possible way, the fourth threshold or the second coefficient is carried in the first information. In other words, the network device indicates the fourth threshold or the second coefficient to the terminal device through the first information. The above thresholds or coefficients can also be predefined. Among them, the third threshold of the second timer is the configured duration of the second timer. When the running duration of the timer reaches the configured duration, that is, the timer expires.

[0258] Optionally, the condition for triggering the SHR can be that the ratio of the running duration of the second timer to the configured duration of the second timer is greater than or equal to threshold A, or the running duration of the second timer is greater than or equal to threshold B

[0259] For example, the fourth threshold of the second timer is configured as 3 or the second coefficient is configured as 60%, and the first threshold of the second timer is configured as 5. When the running duration of the second timer is 4, the running duration of the first timer meets the SHR trigger condition.

[0260] Alternatively, the condition for triggering the SHR is that the running duration of the third timer is less than the fifth threshold and greater than or equal to the sixth threshold, where the sixth threshold is the product of the fifth threshold and the third coefficient, and the third coefficient is a positive number less than 1, or the sixth threshold is a value less than the fifth threshold.

[0261] The sixth threshold or the third coefficient can be configured. In one possible way, the sixth threshold or the third coefficient is carried in the first information. In other words, the network device indicates the sixth threshold or the third coefficient to the terminal device through the first information. The above thresholds or coefficients can also be predefined. Among them, the fifth threshold of the third timer is the configured duration of the first timer. When the running duration of the timer reaches the configured duration, that is, the timer expires.

[0262] Optionally, the condition for triggering the SHR can be that the ratio of the running duration of the third timer to the configured duration of the third timer is greater than or equal to threshold A, or the running duration of the second timer is greater than or equal to threshold B

[0263] For example, the fifth threshold of the third timer is configured as 3 or the third coefficient is configured as 60%, and the fifth threshold of the third timer is configured as 5. When the running duration of the second timer is 4, the running duration of the first timer meets the SHR trigger condition.

[0264] Alternatively, the condition for triggering the SHR is that the running duration of the fifth timer is less than the eighth threshold and greater than or equal to the ninth threshold, where the ninth threshold is the product of the eighth threshold and the fourth coefficient, and the fourth coefficient is a positive number less than 1, or the ninth threshold is a value less than the eighth threshold. The ninth threshold or the fourth coefficient can be configured. In one possible way, the ninth threshold or the fourth coefficient is carried in the first information. Among them, the eighth threshold of the third timer is the configured duration of the fifth timer. When the running duration of the timer reaches the configured duration, that is, the timer expires.

[0265] It should be understood that other methods capable of determining whether the running duration of the timer has expired should all be within the protection scope of this application. For example, other operations or processes such as multiplication, subtraction, addition, or taking logarithms that can compare magnitude relationships.

[0266] The source cell is the cell where the terminal device was located before handover.

[0267] 4. Fourth timer

[0268] 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 transmission or receives the first downlink data. That is, the running duration of the fourth timer is 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.

[0269] The condition for triggering the SHR is related to the fourth timer, including: the condition for triggering the SHR is that the running duration of the fourth timer is greater than or equal to the seventh threshold.

[0270] The seventh threshold can be predefined or configured. In one possible way, the seventh threshold is carried in the first information.

[0271] 5. LTM fast recovery

[0272] LTM fast recovery is used for the terminal device to switch to a candidate cell. The candidate cell can 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.

[0273] 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. Specifically, it can refer to the foregoing description. The terminal device applies the saved candidate cell configuration information and accesses the candidate cell in a random access or non-random access manner (the same as the above cell handover process, cell switch). Conversely, if the selected cell 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 where the LTM cell switch is successful.

[0274] The condition for triggering the SHR is related to LTM fast recovery, including: the condition for triggering the SHR is that the terminal device executes LTM fast recovery or the terminal device executes LTM fast recovery successfully.

[0275] That is, when the terminal device performs LTM fast recovery, or when the terminal device successfully performs LTM fast recovery, the SHR can be recorded.

[0276] S620, the terminal device records the first report.

[0277] Exemplarily, when the terminal device determines that the trigger condition is met, it records the first report. The specific determination method can refer to the description in S610 and will not be elaborated here.

[0278] S630, the terminal device sends the first report to the network device. Correspondingly, the network device receives the first report.

[0279] Optionally, the method may further include:

[0280] S640, the network device adjusts the mobility parameters according to the first report.

[0281] Exemplarily, the network side analyzes according to the first report, and correspondingly optimizes the LTM process and related parameters, such as indicating a more reasonable target cell for the terminal device to prevent the terminal device from switching to an unreasonable cell. Or indicating to 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, reducing the probability of handover failure or radio link failure, and reducing the impact of data transmission interruption time on the user experience.

[0282] In this method, by setting the trigger condition of the first report (such as the SHR), the network side controls the recording and collection of the first report in the LTM scenario. When the terminal device records the first report, it can feedback to the network device. The network device can optimize the mobility parameters according to the first report, thereby reducing the data transmission interruption delay during handover and reducing the probability of handover failure.

[0283] An embodiment of this application also proposes a communication method. The following uses the SHR as an example of the first report. As Figure 7 shown, the method may include the following steps:

[0284] S710, the terminal device records the SHR.

[0285] The SHR is used to indicate information during the mobility process of the terminal device at layer 1 / layer 2.

[0286] Exemplarily, the SHR includes one or more of the trigger conditions for the satisfied SHR (or the reasons for triggering the recording of the SHR, the reasons for triggering the reporting of the SHR). The reporting reason of the SHR is related to at least one of the early TA of the target cell, the first timer, the second timer, the third timer, the fourth timer, or the LTM fast recovery.

[0287] The reporting reasons of SHR are related to the early TA of the target cell, including: The SHR reasons include that there is no available TA value in the target cell. Further, the reasons for SHR can be divided into two types. One is that the terminal device and the target cell have not performed early TA acquisition, and the other is that the terminal device and the target cell have performed early TA acquisition, but no available TA value has been obtained. When the terminal device indicates the SHR reason, it can indicate that there is no available TA value in the target cell, or it can indicate that there is no available TA value in the target cell. Both of these situations apply.

[0288] SHR may include early TA information. The early timing advance information includes at least one of whether the terminal device has performed early timing advance in the target cell, the number of times the terminal device receives the PDCCH instruction indicating the target cell, the beam identification information tried for performing early timing advance, the number of preambles sent through the tried beam, the physical random access channel PRACH resource information, the information corresponding to the candidate cell indicating that the terminal device performs early timing advance, or the information of the target cell.

[0289] The reporting reasons of SHR are related to the first timer, including: The SHR reasons include that the running duration of the first timer is less than the first threshold and greater than or equal to the second threshold, where the second threshold is the product of the first threshold and the 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 configured.

[0290] The reporting reasons of SHR are related to the second timer, including: The SHR reasons include that the running duration of the second timer is less than the third threshold and greater than or equal to the fourth threshold.

[0291] Wherein, the fourth threshold is the product of the third threshold and the second coefficient, and the second coefficient is a positive number less than 1, or the fourth threshold is a value less than the third threshold.

[0292] The reporting reasons of SHR are related to the third timer, including: The running duration of the third timer is less than the fifth threshold and greater than or equal to the sixth threshold.

[0293] Wherein, the sixth threshold is the product of the fifth threshold and the third coefficient, and the third coefficient is a positive number less than 1, or the sixth threshold is a value less than the fifth threshold.

[0294] The reporting reasons of SHR are related to the third timer, including: including that the running duration of the fourth timer is greater than or equal to the seventh threshold.

[0295] The reporting reasons of the SHR are related to the fifth timer, including: the running duration of the fifth timer is less than the eighth threshold value and greater than or equal to the ninth threshold value, where 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.

[0296] The reporting reasons of the SHR include: the terminal device performs LTM fast recovery.

[0297] Among them, the unavailable 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 of the target cell can refer to the description in S610 and will not be elaborated here.

[0298] Optionally, the SHR may further include fast recovery process information. The fast recovery process information includes information of one or more candidate cells for fast recovery, and / or the duration from the terminal device's handover failure to successfully accessing one of the one or more candidate cells. The information of the cell may include at least one of cell identification information, layer 1 and / or layer 3 measurement results corresponding to the cell, and 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 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 duration of the first timer.

[0299] The SHR may also include cell information. The cell information includes information of at least one of the terminal device's current serving cell (i.e., the source cell), the terminal device's target cell, or neighboring cells. 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 indication information whether the neighboring cell is an LTM candidate cell. Among them, the LTM candidate cell is the cell that allows the terminal device to access when the handover fails.

[0300] The SHR may also include the access type of the terminal device. The access type includes access without random access or random access, or the access type is access without random access, or whether the access type is access without random access.

[0301] The SHR may also include cell handover process information based on random access. The cell handover process information based on random access indicates information of two-step random access steps and / or four-step random access steps. For the specific information type, name, or function of the information, reference can be made to the previous description of the two-step random access steps and / or four-step random access steps.

[0302] It should be understood that there are three ways to indicate "whether" in this application. One way is to indicate true, another way is to indicate false, and another way is to indicate true or false. For example, for whether the terminal device has performed early timing advance in the target cell, one way is to indicate that the terminal device has performed early timing advance in the target cell only when the terminal device has performed early timing advance in the target cell. Another way is to indicate that the terminal device has not performed early timing advance in the target cell only when the terminal device has not performed early timing advance in the target cell. Another way is to be able to indicate that the terminal device has performed early timing advance in the target cell and also be able to indicate that the terminal device has not performed early timing advance in the target cell. For other content indicating "whether" in this article, the explanations here can be referred to, such as "whether the neighboring cell belongs to one or more candidate cells".

[0303] In addition, it should also be noted that in the case of indicating "A or B" in this application, it can be to indicate A or B, or to indicate A, or to indicate whether it is A, or to indicate B, or to indicate whether it is B. For example, to indicate the access type of the terminal device, it can be to indicate access without random access or random access. It can also be to indicate access without random access. It can also be to indicate whether it is access without random access. It can also be to indicate random access. It can also be to indicate whether it is random access. "Not random access" can be understood as "access without random access".

[0304] S720, the terminal device sends an SHR to the network device. Correspondingly, the network device receives the SHR.

[0305] Optionally, the method may further include:

[0306] S730, the network device adjusts the mobility parameters according to the SHR.

[0307] Specifically, the network device adjusting the mobility parameters can refer to the description in S640 and will not be elaborated here.

[0308] In this method, the SHR contains relevant information content under the LTM scenario, enabling the UE to record potential problem information in the case of successful LTM handover. The network side can detect the occurrence of non-optimal LTM handover events, perform relevant mobility parameter optimization, reduce handover interruption delay, and reduce the probability of handover failure.

[0309] It should be understood that the methods proposed in the above two embodiments can be used as independent solutions respectively or can be combined 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, and the SHR includes at least one of the information in S710.

[0310] For the convenience of clearly understanding the solution of this application, the following uses gNB-CU as an example of a network device and UE as an example of a terminal device to give a process example applicable to the above technical solution.

[0311] As Figure 8 shown, this process includes the following steps:

[0312] S810, the CU obtains the RRC configuration information of the candidate cell.

[0313] Optionally, the gNB-CU decides to initiate an LTM (L1 / L2-triggered mobility) process based on a measurement report received from the UE that contains L3 measurement results.

[0314] It should be noted that the candidate cell may be a cell managed by the source CU or may be a cell managed by other CUs. In these two cases, the information transmission and reception of the CU are different. Specifically,

[0315] If it is an inter-CU case, that is, the candidate cell is a cell managed by other CUs, as Figure 9 shown in (a) of, the source CU (CU1) sends a handover request message to the candidate CU (CU2), and indicates the candidate cell in this message. For example, carry the cell identifier of the candidate cell. The candidate CU (CU2) indicates the candidate cell to the managed candidate DUs (such as DU2 and DU3). If the candidate DU accepts the request, it sends the lower-layer RRC configuration of the candidate cell to the candidate CU to which the DU belongs, such as sending a handover request response, and carrying the RRC configuration of the candidate cell in this handover request response.

[0316] If it is not an inter-CU case (Intra-CU), that is, the candidate cell is a cell managed by this CU, as Figure 9 shown in (b) of, the CU indicates the candidate cell to the managed candidate DUs (such as DU1, DU2, and DU3). For example, send a handover request message, and this handover request message carries the identifier of the candidate cell. If the candidate DU accepts the request, it sends the lower-layer RRC configuration information of the candidate target cell to the CU, such as sending a handover request response, and carrying the RRC configuration of the candidate cell in this handover request response.

[0317] The candidate cell may be one or more of the foregoing candidate cells.

[0318] S820, the CU sends an RRC reconfiguration message to the UE through the DU. Correspondingly, the UE receives this RRC reconfiguration message.

[0319] The RRC reconfiguration message contains L1 / L2 mobility configuration information. The L1 / L2 mobility configuration information may include configuration information of one or more candidate cells, may further include whether RAR is configured for the candidate cells, and further includes L1 measurement control information.

[0320] To reduce the data interruption time between the UE and the source cell due to the CFRA of 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 an RAR from the source cell or does not receive an RAR. Whether the UE receives an RAR is configured by the network side. For example, the network device indicates to the UE whether RAR is configured for each candidate cell among one or more candidate cells. 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.

[0321] Optionally, S830, the UE performs early uplink synchronization and / or downlink synchronization with the candidate cell.

[0322] For example, before the UE receives the LTM command, the serving DU of the UE may trigger the UE to perform early TA acquisition of the candidate cell. Specifically, the serving DU indicates a contention-free random access CFRA resource, such as an SSB beam, a PRACH resource, and / or a preamble identifier, to the UE by means of a PDCCH order, and the serving DU also indicates the ID of the candidate cell to the UE.

[0323] The UE sends a random access preamble to the candidate cell. The UE performs cell search to achieve early downlink synchronization with the candidate cell.

[0324] Exemplarily, the UE performs early uplink synchronization and / or downlink synchronization with candidate cells DU2 and DU3.

[0325] S840, the DU sends an LTM command to the UE. Correspondingly, the UE receives the LTM command.

[0326] The LTM command includes identification information of the target cell. In one possible way, the LTM command may be sent to the UE by means of MAC CE. In another possible way, the LTM command may be other information from L1 / L2.

[0327] Optionally, before the DU sends the LTM command, the UE sends L1 measurement results to the DU. The DU determines the target cell according to the L1 measurement results, sends an LTM command to the UE, and indicates the target cell through the LTM command.

[0328] It should be understood that the order of early uplink synchronization, early downlink synchronization of the UE, and the UE reporting L1 measurement results is not limited in the embodiments of this application.

[0329] Among them, 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 for uplink / downlink data transmission in the target cell.

[0330] 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 (available TA value) of the target cell, it performs RAHC-less to access the target cell, otherwise it initiates a random access to the target cell.

[0331] The UE obtains the TA value of the target cell in the following ways:

[0332] Method 1: If the target cell is configured with a RAR, the UE receives the TA value of the target cell through the RAR before the LTM command. Exemplarily, the RAR may be sent by the current DU to the UE, or sent from the target cell to the UE, without limitation.

[0333] Method 2: If the target cell is not configured with a RAR, the TA value of the target cell is indicated in the LTM command.

[0334] When the UE does not obtain the TA value of the target cell, or rather, the UE does not obtain the available TA value of the target cell, the UE records a first report (such as SHR). The first report may include at least one of whether the UE has performed early timing advance in the target cell, the number of times the UE receives the PDCCH instruction indicating the target cell, the attempted beam identification information, the number of preambles sent through the attempted beam, the physical random access channel PRACH resource information, the information corresponding to the candidate cell indicating that the UE performs early timing advance, or the information of the target cell.

[0335] S850, the DU sends an LTM notification to the CU. Correspondingly, the CU receives the LTM notification.

[0336] The LTM notification is used to notify the CU of the initiation of the LTM command. Optionally, the LTM notification further includes the identification information of the target cell.

[0337] S860, the UE performs an LTM cell switch.

[0338] The UE switches the cell to the target cell. Exemplarily, the UE performs the cell switch without random access or in a random-access-based manner. In other words, the types of cell switch include without random access or random-access-based. For example, the UE switches the cell DU1 to DU2.

[0339] In a possible implementation, the UE can detect the cell switch status based on the first timer (also referred to as the LTM supervision timer) described above. The cell switch status includes successful cell switch or failed cell switch.

[0340] When the first timer expires, the UE can record the first report (such as SHR). This first report can include the running duration of the first timer.

[0341] Optionally, S870, the UE performs the LTM fast recovery process.

[0342] If the cell switch of S860 fails or soon after the radio link failure (RLF) of the target cell, the UE can access a candidate cell through the LTM fast recovery process.

[0343] In a possible way, the UE performs cell selection, and the selected cell is an LTM candidate cell. The UE applies the saved configuration information of this candidate cell and accesses this candidate cell in a random-access or non-random-access manner (the same as the above cell switch process).

[0344] In another possible way, if the cell selected by the UE is not a candidate cell, or in other words, the cell selected by the UE is not in the candidate cells configured by the network side, the UE initiates the RRC reconstruction process.

[0345] It should be understood that when the UE successfully performs the LTM fast recovery process, that is, the UE successfully accesses the candidate cell through the LTM fast recovery process, it can also be regarded as a scenario of successful LTM cell switch.

[0346] When the UE performs the LTM fast recovery process, it can record the first report (such as SHR). This first report can include information about one or more candidate cells for fast recovery, and / or the time between the UE's switch failure and successful access to a candidate cell.

[0347] Specifically, regarding the trigger of the first report and / or the content included in the first report, reference can be made to the above description and will not be elaborated here.

[0348] In this implementation process, when the triggering condition is met, the network side controls the first report in the LTM scenario, such as the recording and collection of SHR. The SHR covers relevant information in the LTM process. The terminal device records the SHR and feeds it back to the network device, and the network device can optimize the mobility parameters based on the SHR, thereby reducing the handover interruption delay and the probability of handover failure.

[0349] It can be understood that some optional features in the embodiments of the present application can, in some scenarios, be independent of other features, and in some scenarios, can be combined with other features, without limitation.

[0350] It can also be understood that the solutions in the 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.

[0351] It can also be understood that in the above method embodiments, the methods and operations implemented by the communication device can also be implemented by components (such as chips or circuits) that make up the communication device.

[0352] Corresponding to the methods given in the above method embodiments, the embodiments of the present application also provide corresponding devices, and the devices include modules for executing the corresponding ones of the above method embodiments. The module can be software, hardware, or a combination of software and hardware. It can be understood that the technical features described in the above method embodiments also apply to the following device embodiments.

[0353] Figure 10 It is a schematic block diagram of a communication device 1000 provided by 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.

[0354] Optionally, the device 1000 further includes a processing unit 1020. The processing unit 1020 can be used for information processing.

[0355] Optionally, the device 1000 further 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 foregoing method embodiments.

[0356] In one design, the device 1000 may be the terminal device in the foregoing embodiments, or a component of the terminal device (such as a chip). The device 1000 can implement the steps or processes performed by the terminal device in the method embodiments above. Among them, the transceiver unit 1010 can be used to perform the operations related to the transceiver of the terminal device in the method embodiments above, and the processing unit 1020 can be used to perform the operations related to the processing of the terminal device in the method embodiments above.

[0357] In a possible implementation, the transceiver unit 1010 is configured to receive first indication information; it can also be used to send a first report.

[0358] In another possible implementation, the processing unit 1020 is configured to switch cells and can also be used to record the first report.

[0359] The device 1000 can implement the steps or processes performed by the terminal device in the method embodiments according to the embodiments of the present application. The device 1000 may include units for performing Figures 6 to 9 the method performed by the terminal device in the illustrated embodiments.

[0360] In another design, the device 1000 may be the network device in the foregoing embodiments, or a component of the network device (such as a chip). The device 1000 can implement the steps or processes performed by the network device in the method embodiments above. Among them, the transceiver unit 1010 can be used to perform the operations related to the transceiver of the network device in the method embodiments above, and the processing unit 1020 can be used to perform the operations related to the processing of the network device in the method embodiments above.

[0361] In a possible implementation, the processing unit 1020 is configured to process and send the first indication information.

[0362] In another possible implementation, the transceiver unit 1010 is configured to receive the first report.

[0363] The device 1000 can implement the steps or processes performed by the network device in the method embodiments according to the embodiments of the present application. The device 1000 may include units for performing Figures 6 to 9 the method performed by the network device in the illustrated embodiments.

[0364] A more detailed description of the device 1000 can be directly obtained from the relevant descriptions in the foregoing method embodiments and will not be elaborated here.

[0365] It should be understood that the specific processes for each unit to perform the corresponding steps above have been described in detail in the foregoing method embodiments. For the sake of brevity, they will not be elaborated here.

[0366] It should also be understood that the apparatus 1000 herein is embodied in the form of functional units. The term "unit" herein 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 of processors, etc.) for executing one or more software or firmware programs, and a memory, a combined logic circuit, and / or other suitable components that support the described functions. In an alternative example, those skilled in the art can understand that the apparatus 1000 may specifically be a communication apparatus (such as a terminal device or a network device) in the above embodiments, and can be used to execute each process and / or step corresponding to the communication apparatus in the above method embodiments. To avoid repetition, it will not be elaborated herein.

[0367] The apparatus 1000 of each of the above solutions has the function of implementing the corresponding steps executed by the communication apparatus (such as a terminal device or a network device) in the above method. The function can be implemented by hardware or by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above 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 execute the transceiver operations and related processing operations in each method embodiment.

[0368] In addition, the above transceiver unit 1010 may also be a transceiver circuit (for example, it may include a receiving circuit and a sending circuit), and the processing unit may be a processing circuit.

[0369] It should be noted that Figure 10 the apparatus in may be the device in the foregoing embodiments, or a chip or a chip system, for example: a system on chip (SoC). Among them, the transceiver unit may be an input / output circuit, a communication interface; the processing unit is a processor, a microprocessor, or an integrated circuit integrated on the chip. It is not limited herein.

[0370] Figure 11 FIG. 15 is a schematic block diagram of a communication apparatus 1100 provided by an embodiment of the present application. The apparatus 1100 includes a processor 1110, and the processor 1110 is coupled to a memory 1120. Optionally, it further includes a memory 1120 for storing computer programs or instructions and / or data, and the processor 1110 is used to execute the computer programs or instructions stored in the memory 1120, or read the data stored in the memory 1120 to execute the methods in the above method embodiments.

[0371] Optionally, the processor 1110 is one or more.

[0372] Optionally, there is one or more memories 1120.

[0373] Optionally, the memory 1120 is integrated with the processor 1110 or is separately provided.

[0374] Optionally, as Figure 11 shown, the device 1100 further includes a transceiver 1130, and the transceiver 1130 is used for receiving and / or sending signals. For example, the processor 1110 is used to control the transceiver 1130 to receive and / or send signals.

[0375] As a solution, the device 1100 is used to implement the operations performed by the communication device in the above method embodiments.

[0376] For example, the processor 1110 is used to execute the computer programs or instructions stored in the memory 1120 to implement the related operations of the terminal device or the network device in the above method embodiments.

[0377] In the implementation process, each step of the above method can be completed by the integrated logic circuit in the hardware of the processor 1110 or the instructions in software form. The method disclosed in combination with the embodiments of the present application can be directly embodied as being executed and completed by the hardware processor, or executed and completed by the combination of the 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. This storage medium is located in the memory 1120, and the processor 1110 reads the information in the memory 1120 and combines its hardware to complete the steps of the above method. To avoid repetition, it will not be described in detail here.

[0378] It should be understood that in the embodiments of the present application, the processor can be one or more integrated circuits for executing related programs to execute the method embodiments of the present application.

[0379] A processor (e.g., processor 1110) may include one or more processors and be implemented as a combination of computing devices. The processor may respectively 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), gated logic, transistor logic, discrete hardware circuitry, processing circuitry, or other suitable hardware, firmware, and / or a combination of hardware and software for performing the various functions described in the present 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. The baseband processor may be used to process communication protocols and communication data. The central processing unit may be used to cause the device to execute software programs and process data in the software programs. In addition, a part of the processor may further include non-volatile random access memory. For example, the processor may also store information about the device type.

[0380] The program in the present application is generally used to represent software. Non-limiting examples of software include: program code, programs, subroutines, instructions, instruction sets, code, code segments, software modules, application programs, or software applications, etc. The program may run on a processor and / or a computer so that the device performs the various functions and / or processes described in the present application.

[0381] A memory (e.g., memory 1120) may store data required for a processor (e.g., processor 1110) to execute software. The memory may be implemented using any suitable storage technology. For example, the memory may be any available storage medium accessible 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 random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchlink dynamic random access memory (SLDRAM), and direct rambus random access memory (DR RAM), removable media, optical disc memory, disk storage media, magnetic storage devices, flash memory, registers, status memory, remotely mounted memory, local or remote memory components, or any other medium capable of carrying or storing software, data, or information and accessible by the 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.

[0382] The memory (e.g., memory 1120) and the processor (e.g., processor 1110) may be separately provided or integrated together. The memory may be used to connect to the processor such that the processor can read information from the memory, store and / or write information in the memory. The memory may be integrated in 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).

[0383] Figure 12 It is a schematic block diagram of a chip system 1200 provided by an embodiment of the present application. The chip system 1200 (or may also be referred to as a processing system) includes a logic circuit 1210 and an input / output interface 1220.

[0384] Among them, the logic circuit 1210 can be the processing circuit in the chip system 1200. The logic circuit 1210 can be coupled to a storage unit to call instructions in the storage unit, enabling the chip system 1200 to implement the methods and functions of the embodiments of the present application. The input / output interface 1220 can be the input / output circuit in the chip system 1200, outputting the information processed by the chip system 1200, or inputting the data or signaling information to be processed into the chip system 1200 for processing.

[0385] As a solution, the chip system 1200 is used to implement the operations performed by the communication device in the above method embodiments.

[0386] 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 Figure 3 the processing-related operations performed by the terminal device in the illustrated embodiment; 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 Figure 3 the sending and / or receiving-related operations performed by the terminal device in the illustrated embodiment.

[0387] 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 Figure 3 the processing-related operations performed by the network device in the illustrated embodiment; 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 Figure 3 the sending and / or receiving-related operations performed by the network device in the illustrated embodiment.

[0388] The embodiments of the present application further provide a computer-readable storage medium, on which computer instructions for implementing the methods performed by the communication device (such as a terminal device or a network device) in the above method embodiments are stored.

[0389] The embodiments of the present application further provide a computer program product, including instructions, which when executed by a computer, implement the methods performed by the communication device (such as a terminal device or a network device) in the above method embodiments.

[0390] The embodiments of the present application further provide a communication system, which includes the terminal device and the network device in the above embodiments.

[0391] The explanations and beneficial effects of the relevant content in any of the above provided devices can refer to the corresponding method embodiments provided above, and will not be elaborated here.

[0392] In several embodiments provided by the present 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 merely illustrative. For example, the division of the above-mentioned units is only a logical function division. In actual implementation, there may be other division methods. 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 displayed or discussed coupling or direct coupling or communication connection between each other can be through some interfaces. The indirect coupling or communication connection of devices or units can be in electrical, mechanical or other forms.

[0393] The units described above as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they can be located in one place, or distributed to multiple network units. Some or all of the units can be selected according to actual needs to implement the solution provided by the present application.

[0394] In addition, each functional unit in various embodiments of the present application can be integrated into one unit, or each unit can exist physically alone, or two or more units can be integrated into one unit.

[0395] Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present application.

[0396] When implemented using software, 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 processes or functions described in the embodiments of the present application are 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, a computer, a server, or a data center to another website, a computer, a server, or a data center by wire (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (such as infrared, wireless, microwave, etc.). Regarding the computer-readable storage medium, reference can be made to the above description.

[0397] As described above, it is only the specific implementation manner of the present application. However, the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should all be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims described above.

Claims

1. A communication method, characterized in that, it includes: The terminal device receives first indication information sent via a media access control control element, and the first indication information instructs the terminal device to switch 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, and the first report is used to indicate information during the layer 1 / layer 2 mobility process of the terminal device; The terminal device sends the first report.

2. The method according to claim 1, characterized in that, the method further includes: The terminal device receives first information, and the first information instructs the terminal device to record the first report when it is in the layer 1 or layer 2 mobility process and meets the triggering condition, where the first information includes the triggering condition.

3. The method according to claim 2, characterized in that, the triggering condition is related to at least one of the target cell, the running duration of a first timer, the running duration of a second timer, the running duration of a third timer, the running duration of a fourth timer, the running duration of a fifth timer, or fast recovery, The running duration of the first timer is the duration 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 duration of the second timer is the duration from when the terminal device detects a physical layer out-of-sync problem with the source network device to when the terminal device receives the first indication information, The running duration of the third timer is, during the running of the second timer, the duration from when the terminal device triggers the sending of a measurement report to when the terminal device receives the first indication information, The running duration of the fourth timer is the duration between when the terminal device receives the first indication information and 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 when the terminal receives or applies a radio resource control (RRC) reconfiguration message with a synchronization function to when the terminal device completes random access or when the terminal device receives a downlink physical control channel transmission after the first uplink transmission without random access.

4. The method according to claim 3, characterized in that, the triggering condition is related to the target cell, and the triggering condition is: The terminal device does not obtain an available early timing value for the target cell, and the early timing value is used for 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 not obtaining the early timing value for the target cell includes: The terminal device does not perform early timing acquisition with the target cell, or, The terminal device performs early timing acquisition with the target cell and does not obtain an available early timing value.

6. The method according to claim 3, characterized in that, The triggering condition is related to the running duration of the first timer, and the triggering condition is as follows: The running duration 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.

7. The method according to claim 3, wherein, The triggering condition is related to the running duration of the second timer, and the triggering condition is as follows: The running duration 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.

8. The method according to claim 3, wherein, The triggering condition is related to the running duration of the third timer, and the triggering condition is as follows: The running duration of the third timer is less than a fifth threshold value and greater than or equal to a sixth threshold value, wherein, the sixth threshold value is the product of the fifth threshold value and a 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.

9. The method according to claim 3, wherein, The triggering condition is related to the running duration of the fourth timer, and the triggering condition is as follows: The running duration of the fourth timer is greater than or equal to a seventh threshold value.

10. The method according to claim 3, wherein, The triggering condition is related to the running duration of the fifth timer, and the triggering condition is as follows: The running duration of the fifth timer is less than an eighth threshold value and greater than or equal to a ninth threshold value, wherein, the ninth threshold value is the product of the eighth threshold value and a 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.

11. The method according to claim 3, wherein, The triggering condition is related to the fast recovery, and the triggering condition is as follows: 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, wherein, The first report includes one or more of the following information: One or more of the triggering conditions of the first report that are satisfied; Early timing information; Cell information; Target cell access information; Fast process recovery information.

13. The method according to claim 12, wherein, The first report includes early timing advance information, and the early timing advance information includes at least one of whether the terminal device has performed early timing advance in the target cell, the number of times the terminal device receives a physical downlink control channel (PDCCH) instruction indicating the target cell, the beam identification information tried for performing early timing advance, the number of preambles transmitted through the tried beam, physical random access channel (PRACH) resource information, information corresponding to a candidate cell indicating that the terminal device performs early timing advance, or information of the target cell.

14. The method according to claim 12, wherein, the first report includes fast recovery process information, and the fast recovery process information includes information of one or more candidate cells for fast recovery, and / or the duration from the terminal device's handover failure to successfully accessing one of the one or more candidate cells.

15. The method according to claim 12, wherein, the first report further includes time information, and the time information includes at least one of the running duration of the fourth timer, the duration 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 the running duration of the first timer.

16. The method according to claim 12, wherein, the first report further includes cell information, and the cell information includes information of at least one of the terminal device's current serving cell, the target cell of the terminal device, or a neighboring cell. The cell information includes cell identification information, layer 1 and / or layer 3 measurement results corresponding to the cell, whether the neighboring cell belongs to the one or more candidate cells, the neighboring cell being a cell other than the current serving cell measured by the terminal device, and the one or more candidate cells being cells that allow the terminal device to access when a handover fails.

17. The method according to claim 12, wherein, the first report further 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, wherein, 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, wherein, it includes: The network device sends first indication information, and the first indication information instructs the terminal device to switch to a target cell. 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 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 layer 1 / layer 2 mobility process performed by the terminal device.

20. The method according to claim 19, wherein, the method further comprises: the network device sends first information, and the first information instructs the terminal device to record the first report when the terminal device is in a mobility process at layer 1 or layer 2 and meets a triggering condition, wherein the first information includes the triggering condition.

21. The method according to claim 19 or 20, wherein, the triggering condition is related to at least one of the target cell, the running duration of a first timer, the running duration of a second timer, the running duration of a third timer, the running duration of a fourth timer, the running duration of a fifth timer, or fast recovery, the running duration of the first timer is the duration 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 duration of the second timer is the duration from when the terminal device detects a physical layer out-of-sync problem with the source network device to when the terminal device receives the first indication information, the running duration of the third timer is, during the running of the second timer, the duration from when the terminal device triggers the sending of a measurement report to when the terminal device receives the first indication information, the running duration of the fourth timer is the duration between when the terminal device receives the first indication information and 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 when the terminal receives or applies a radio resource control (RRC) reconfiguration message with a synchronization function to when the terminal device completes random access or when the terminal device receives a downlink physical control channel transmission after the first uplink transmission in the case of random access exemption.

22. The method according to claim 21, wherein, the triggering condition is related to the target cell, and the triggering condition is: the terminal device has no available pre-timing value for the target cell, and the pre-timing value is used for the terminal device to obtain uplink synchronization with the target cell to avoid random access.

23. The method according to claim 21, wherein, the triggering condition is related to the running duration of the first timer, and the triggering condition is: the running duration 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.

24. The method according to claim 21, wherein, the triggering condition is related to the running duration of the second timer, and the triggering condition is: the running duration 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.

25. The method according to claim 21, wherein, The triggering condition is related to the running duration of the third timer, and the triggering condition is as follows: The running duration of the third timer is less than a fifth threshold value and greater than or equal to a sixth threshold value, wherein, the sixth threshold value is the product of the fifth threshold value and a 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, wherein, The triggering condition is related to the running duration of the fourth timer, and the triggering condition is as follows: The running duration of the fourth timer is greater than or equal to a seventh threshold value.

27. The method according to claim 21, wherein, The triggering condition is related to the running duration of the fifth timer, and the triggering condition is as follows: The running duration of the fifth timer is less than an eighth threshold value and greater than or equal to a ninth threshold value, wherein, 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, wherein, The triggering condition is related to the fast recovery, and the triggering condition is as follows: 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, wherein, The first report includes one or more of the following information: One or more of the triggering conditions of the first report that are satisfied; Early timing advance information; Cell information; Target cell access information; Fast process recovery information.

30. The method according to claim 29, wherein, The first report includes early timing advance information, and the early timing advance information includes at least one of whether the terminal device performs early timing advance in the target cell, the number of times the terminal device receives a PDCCH instruction indicating the target cell, the beam identification information tried for performing early timing advance, the number of preambles sent through the tried beam, PRACH resource information, information corresponding to the candidate cell indicating that the terminal device performs early timing advance, or information of the target cell.

31. The method according to claim 29, wherein, The first report includes fast recovery process information, and the fast recovery process information includes information of one or more candidate cells for fast recovery, and / or, the duration from the handover failure of the terminal device to the successful access to one of the one or more candidate cells.

32. The method according to claim 29, wherein, The first report further includes time information, and the time information includes at least one of the running duration of the fourth timer, the time between the terminal device receiving 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 the running duration of the first timer.

33. The method according to claim 29, wherein, the first report further includes cell information, and the cell information includes information of at least one of the current serving cell of the terminal device, the target cell of the terminal device, or 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 cell is a cell other than the current serving cell measured by the terminal device, and the one or more candidate cells are cells that allow the terminal device to access when handover fails.

34. The method according to claim 29, wherein, the first report further 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, wherein, 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.

36. A communication device, wherein, it includes a module for executing the method according to any one of claims 1 to 18.

37. A communication device, wherein, it includes a module for executing the method according to any one of claims 19 to 35.

38. A communication system, wherein, it includes the communication devices according to claims 34 and 35.

39. A computer-readable storage medium, wherein, a computer program or instruction is stored on the computer-readable storage medium, and when the computer program or instruction runs 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, wherein, the computer program product includes an instruction for executing the method according to any one of claims 1 to 35.

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