Communication method, apparatus, and storage medium

Abstract

The embodiments of the present application belong to the technical field of communications. Provided are a communication method, an apparatus and a storage medium. The method comprises: a UE receives a TA of at least one alternative cell and, on the basis of the TA of a first alternative cell among the at least one alternative cell, initiates a conditional handover to the first alternative cell, the first alternative cell being a cell among the at least one alternative cell satisfying a trigger condition for the conditional handover; and, before a target cell is determined and a cell handover is performed, a network device informs a UE of the TA of the at least one alternative cell, so that the UE promptly acquires the TA in a conditional LTM process.

Description

Communication method, apparatus, and storage medium

[0001] The present application claims priority to the Chinese patent application No. 202410660587.2, filed on May 24, 2024, entitled "Communication method, apparatus and storage medium", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the field of communication technology, in particular to a communication method, apparatus and storage medium. BACKGROUND

[0003] In some cases, for example, when the current cell environment of a user equipment (UE) deteriorates, the UE needs to be handed over.

[0004] In the related art, the cell handover can be performed through a layer 1 / 2 triggered mobility (LTM) procedure. In the LTM procedure, a network device provides configuration information of one or more candidate cells for a UE based on a measurement report (e.g., a radio resource management (RRM) measurement report or a layer 3 measurement report) reported by the UE; after the UE receives the configuration information, the UE sends a measurement report (e.g., a layer 1 measurement report) to the network device, and a distributed unit (DU) of the network device determines to trigger the LTM handover based on the measurement report reported by the UE; the original DU sends a LTM cell handover command to the UE through layer 1 signaling and / or layer 2 signaling, so that the UE performs a handover procedure based on an indication in the handover command, and the handover command can include a time advance (TA).

[0005] In a conditional handover (CHO) procedure, the UE determines whether to perform handover according to a handover condition pre-configured by the network device, that is, in the CHO procedure, the network device does not send a handover command to the UE, and if the conditional LTM procedure is to be supported, how to obtain the TA is a technical problem to be solved urgently. SUMMARY

[0006] The present application relates to a communication method, apparatus and storage medium, and provides a method for obtaining a TA in a conditional LTM procedure.

[0007] In a first aspect, an embodiment of the present application provides a communication method, comprising:

[0008] receiving a time advance (TA) of at least one candidate cell;

[0009] initiating a conditional handover to a first candidate cell of the at least one candidate cell based on a TA of the first candidate cell, the first candidate cell being a cell of the at least one candidate cell that satisfies a triggering condition of the conditional handover.

[0010] In a possible implementation, the receiving the TA of the at least one candidate cell comprises:

[0011] receiving the TA of the at least one candidate cell from a serving cell; or,

[0012] receiving a timing advance TA of the at least one candidate cell respectively from the at least one candidate cell.

[0013] In a possible implementation, the method further comprises:

[0014] receiving a TA validation instruction of the first candidate cell sent from the serving cell, the TA validation instruction indicating that the TA of the first candidate cell is valid.

[0015] In a possible implementation, the TA of the first candidate cell is valid within a runtime period of a TA timer of the first candidate cell, and a valid duration of the TA timer of the first candidate cell is a runtime duration of the TA timer of the first candidate cell.

[0016] In a possible implementation, the method further comprises:

[0017] receiving a valid duration of the TA timer of the first candidate cell.

[0018] In a possible implementation, the valid duration of the TA timer of the first candidate cell is a difference between a duration of a TA timer indicated by the first candidate cell to the serving cell and a first delay, the first delay being a communication duration between the first candidate cell and the serving cell.

[0019] In a possible implementation, the method further comprises:

[0020] starting the TA timer of the first candidate cell upon receiving a TA sent by the first candidate cell; or,

[0021] starting the TA timer of the first candidate cell upon receiving a TA validation instruction of the first candidate cell sent by the serving cell.

[0022] In a possible implementation, the first candidate cell is a cell of the at least one candidate cell other than a second candidate cell that satisfies the triggering condition, and a TA of the second candidate cell is invalid.

[0023] In a possible implementation, the method further includes:

[0024] receiving indication information indicating that the TA of the second candidate cell is invalid.

[0025] In a possible implementation, the TA of the second candidate cell is invalid, including:

[0026] the TAT of the second candidate cell is expired.

[0027] In a possible implementation, the method further includes:

[0028] if the TA of the first candidate cell is invalid and the first candidate cell satisfies a triggering condition of conditional handover, initiating random access to the first candidate cell.

[0029] In a second aspect, an embodiment of the present application provides a communication method, including:

[0030] obtaining a timing advance TA of at least one candidate cell;

[0031] sending the TA of the at least one candidate cell.

[0032] In a possible implementation, the sending the TA of the at least one candidate cell includes:

[0033] sending the TA of the at least one candidate cell from a serving cell; or

[0034] sending the TA of the at least one candidate cell from the at least one candidate cell respectively.

[0035] In a possible implementation, the method further includes:

[0036] sending a TA validity instruction of the first candidate cell from a serving cell, the TA validity instruction indicating that the TA of the first candidate cell is valid.

[0037] In a possible implementation, the TA of the first candidate cell is valid within a running period of a time alignment timer TAT of the first candidate cell, and a valid duration of the TAT of the first candidate cell is a running duration of the TAT of the first candidate cell.

[0038] In a possible implementation, the method further includes:

[0039] sending the valid duration of the TAT of the first candidate cell.

[0040] In a possible implementation, the valid duration of the TAT of the first candidate cell is a difference between a duration of the TAT indicated by the first candidate cell to a serving cell and a first time delay, the first time delay being a duration of communication between the first candidate cell and the serving cell.

[0041] In a possible implementation, the first candidate cell is a cell in the at least one candidate cell that meets the triggering condition, except for a second candidate cell, the TA of the second candidate cell being invalid.

[0042] In a possible implementation, the method further includes:

[0043] sending indication information, the indication information indicating that the TA of a second candidate cell is invalid, the second candidate cell being a cell in the at least one candidate cell except for the first candidate cell.

[0044] In a third aspect, an embodiment of the present application provides a communication apparatus, including a receiving module and a processing module, wherein,

[0045] The receiving module is configured to receive a timing advance (TA) of at least one candidate cell.

[0046] The processing module is configured to initiate a conditional handover to a first candidate cell in the at least one candidate cell based on a TA of the first candidate cell, the first candidate cell being a cell in the at least one candidate cell that meets a triggering condition of the conditional handover.

[0047] In a fourth aspect, an embodiment of the present application provides a communication apparatus, including a processing module and a sending module, wherein,

[0048] The processing module is configured to acquire a timing advance (TA) of at least one candidate cell.

[0049] The sending module is configured to send the TA of the at least one candidate cell.

[0050] In a fifth aspect, an embodiment of the present application provides a communication apparatus, including a processor and a memory connected with the processor in communication,

[0051] The memory stores computer-executed instructions.

[0052] The processor executes the computer-executed instructions stored in the memory, so that the processor performs the method in the first aspect or the second aspect.

[0053] In a sixth aspect, an embodiment of the present application provides a computer readable storage medium, wherein the computer readable storage medium stores computer execution instructions, and the computer execution instructions are used to implement the method in the first aspect or the second aspect when executed by a processor.

[0054] In a seventh aspect, an embodiment of the present application provides a computer program product, comprising a computer program, and the computer program is used to implement the method in the first aspect or the second aspect when executed by a processor.

[0055] In an eighth aspect, an embodiment of the present application provides a chip, wherein the chip stores a computer program, and the computer program is used to implement the method in the first aspect or the second aspect when executed by the chip.

[0056] In a possible implementation, the chip is a chip in a chip module.

[0057] Embodiments of the present application provide a communication method, apparatus and storage medium. In the method, a UE receives TAs of at least one candidate cell, and initiates conditional handover to a first candidate cell based on a TA of the first candidate cell among the at least one candidate cell, the first candidate cell being a cell in the at least one candidate cell that meets a trigger condition of conditional handover. Before determining a target cell and performing cell handover, a network device informs the UE of the TAs of the at least one candidate cell, so that the UE acquires the TAs in time in a conditional LTM process. BRIEF DESCRIPTION OF DRAWINGS

[0058] The accompanying drawings, which are incorporated herein and constitute part of the specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0059] FIG. 1 is a flow diagram of cell handover in the related art;

[0060] FIG. 2 is a flow diagram of conditional handover in the related art;

[0061] FIG. 3 is a flow diagram of LTM handover in the related art;

[0062] FIG. 4 is a flow diagram of a communication method according to an embodiment of the present application;

[0063] FIG. 5 is a flow diagram of another communication method according to an embodiment of the present application;

[0064] FIG. 6 is a structural diagram of a communication apparatus according to an embodiment of the present application;

[0065] FIG. 7 is a structural diagram of another communication apparatus according to an embodiment of the present application;

[0066] FIG. 8 is a structural schematic diagram of another communication apparatus according to an embodiment of the present application.

[0067] The specific embodiments of the present application have been shown through the above drawings, and will be described in more detail hereinafter. The drawings and the written description are not intended to restrict the scope of the present application in any way, but to explain the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0068] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all of them. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of the present application.

[0069] In the embodiments of the present application, the term "at least one" means one or more. "Multiple" means two or more.

[0070] In the embodiments of the present application, the term "and / or" is used to describe the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can mean that there are three cases of A alone, A and B together, and B alone. The character " / " generally represents an "or" relationship between the associated objects before and after it.

[0071] The first, second, and the like appearing in the embodiments of the present application are only used for description and distinction of the described objects, and there is no order, nor do they represent a special limitation on the number of objects in the embodiments of the present application, which cannot constitute any limitation on the embodiments of the present application. For example, the first alternative cell and the second alternative cell are only used to distinguish different alternative cells, and do not represent the difference in priority or importance of the two alternative cells.

[0072] In the embodiments of the present application, "example", "in some embodiments", "in another embodiment", and the like are used to represent an example, illustration or explanation. Any embodiment or design scheme described as "example" in the present application should not be interpreted as more preferred or more advantageous than other embodiments or design schemes. Rather, the word "example" is intended to present the concept in a specific way.

[0073] The technical solutions provided by the embodiments of the present application can be applied to various systems. The applicable systems can include, but are not limited to, a narrow band-internet of things (NB-IOT) system, a wideband code division multiple access (WCDMA) system, a code division multiple access (CDMA2000) system, a time division-synchronization code division multiple access (TDSCDMA) system, a long term evolution (LTE) system, a fifth generation mobile communication system or a possible sixth generation, a seventh mobile communication system, a vehicle wireless short-range communication system, and a future mobile communication system.

[0074] The technical solutions provided by the embodiments of the present application are also applicable to different network architectures, including but not limited to a relay network architecture, a dual-link architecture, a Vehicle-to-Everything (V2X) architecture, and the like.

[0075] The UE related to the embodiments of the present application can also be referred to as a terminal, including various forms of access terminals, user units, user stations, mobile stations, mobile stations (MS), remote stations, remote terminals, mobile devices, user terminals, wireless communication devices, user agents or user equipment. The UE can also be a cellular phone, a cordless phone, a session initiation protocol (SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), a handheld device with wireless communication function, a computing device or other processing device connected to a wireless modem, a vehicle-mounted device, a wearable device, a terminal in a 5G network or a terminal in a future evolved public land mobile network (PLMN), and the like. The embodiments of the present application are not limited thereto.

[0076] The network device related to the embodiments of the present application can be an access network device, including a base station, which can include multiple cells serving UEs. According to different application occasions, the base station can also be called an access point, or can be a device in an access network that communicates with wireless terminals over an air interface through one or more sectors, or other names. For example, the network device related to the embodiments of the present application can be an evolved network device (eNB or e-NodeB) in an LTE system, a 5G base station (gNB) in a next generation system (5G network architecture), etc., and can also be a home evolved Node B (HeNB), a relay node, a femto, a pico, a network test device, etc., and the embodiments of the present application are not limited thereto. In some network structures, the network device can include a CU and a DU, and the CU and the DU can also be arranged geographically apart.

[0077] In order to more clearly illustrate the present application, first, the related art related to the present application will be introduced.

[0078] 1. Cell handover

[0079] In new radio (NR), for a UE in a radio resource control (RRC) connected state, if the UE moves from one cell to another cell, the network side will decide whether to perform cell handover according to the measurement result of the UE.

[0080] The procedure of cell handover is shown in FIG. 1. In step 1, when the layer 3 measurement result of the UE meets certain conditions, the UE reports the measurement result through an event. The network side determines the target cell of handover according to the measurement result of the UE, and then sends a handover command to the UE to initiate the handover procedure. In step 8, the UE accesses the target cell through the random access process according to the configuration of the target cell carried in the handover command; in the random access process, the network device to which the target cell belongs determines the TA used by the UE according to the preamble sent by the UE, and sends the TA to the UE, and the UE starts the time alignment timer (TAT) after receiving the TA. The UE can obtain the running time of the TAT through the TAG-Config in the MAC-CellGroupConfig in the system information block (SIB) 1 or the RRC reconfiguration message. The value range of the running time of the TAT can be {500ms, 750ms, 1280ms, 1920ms, 2560ms, 5120ms, 10240ms, ∞}.

[0081] 2. Conditional handover (CHO)

[0082] In order to prevent the network device to which the source cell belongs from failing to timely issue a handover command to the UE due to too violent change of the UE signal, CHO is introduced in NR R16. As shown in FIG. 2, the network side can pre-configure one or more candidate cells and their related configurations for the UE based on the measurement result reported by the UE in advance, and configure a handover condition (including parameters reflecting signal quality such as reference signal received power (RSRP), reference signal received quality (RSRQ), and signal to interference plus noise ratio (SINR) for related event evaluation) at the same time; when the UE meets the handover condition of a candidate cell, the UE can directly hand over to the candidate cell, which can be referred to as a target cell, and the UE can hand over to the target cell by initiating random access to the network device to which the target cell belongs or sending an RRC reconfiguration complete message to the network device to which the target cell belongs, and then the network device to which the target cell belongs can notify the network device to which the source cell belongs to release the UE connection. When the UE autonomously judges and decides to access the target cell, the UE can obtain the TA of the target cell through the random access process and start the corresponding TAT.

[0083] 3. Layer 1 / 2 triggered mobility (LTM) procedure

[0084] In the LTM procedure, the network side can use layer 2 signaling (medium access control (MAC) control element (CE)) to instruct the UE to perform cell switching based on the layer 1 measurement results reported by the UE, so as to reduce the switching delay.

[0085] Currently, the LTM only supports centralized unit (CU) intra-scenario, that is, the cell switching in the LTM is performed under the same base station, and the information interaction is only between the CU and the DU, so the delay is small.

[0086] As shown in FIG. 3, the LTM procedure includes the following four parts:

[0087] (1) LTM preparation: the network side provides the UE with the configuration information of one or more candidate cells according to the measurement results reported by the UE.

[0088] (2) Advance synchronization: the network side can require the UE to perform advance synchronization to one or more candidate cells before switching. The network side can trigger the UE to perform advance synchronization through a physical downlink control channel (PDCCH) command, which can contain non-contention-based preamble information of the candidate cell in the PDCCH command; the UE can send a preamble to the candidate cell based on the non-contention-based preamble information but does not need to wait to receive a random access response (RAR); the network side determines the TA value used by the UE by receiving the preamble of the UE; if the candidate cell is the target cell of the switching, the network device to which the target cell belongs sends the determined TA value to the network device to which the source cell belongs, and subsequently in the LTM execution process, the network device to which the source cell belongs sends the TA value of the target cell to the UE. If the candidate cell is not the target cell of the UE switching, the network device to which the candidate cell belongs can also send the determined TA value to the network device to which the source cell belongs.

[0089] (3) LTM execution: the network side can instruct the UE to periodically report layer 1 measurement results, or instruct the UE to report measurement results at a certain time; the network side determines the target cell of handover according to the measurement results reported by the UE, and sends a cell switch command to the UE, which carries the target configuration identifier, and optionally carries the TA of the target cell, the transmission configuration indicator (TCI) state identifier (ID), the uplink (UL) TCI state ID.

[0090] If the cell switch command carries the TA of the target cell, the UE can not need to access the target cell through a random access process, can directly wait for the target cell to be scheduled through PDCCH, or use a pre-configured configured grant resource to send uplink information to the network device to which the target cell belongs. If the cell switch command does not carry the TA of the target cell, and the UE does not obtain the TA of the target cell through UE-based TA measurement, a random access needs to be initiated to the target cell to complete synchronization and obtain the TA, beam information, etc. of the target cell.

[0091] If the timing advance command is carried in the cell switch command MAC CE, the TAT of the corresponding primary timing advance group (PTAG) is started or restarted.

[0092] (4) LTM completion: the UE can notify the network side of the completion of handover by sending an RRC reconfiguration complete message. If random access is required during the cell switching process, the completion of random access can be considered as the completion of handover. If random access is not required during the cell switching process, the UE considers that the network side successfully receives the first uplink data and considers that the handover is completed.

[0093] In the existing LTM process, the TA can start the TAT when it is carried in the cell switch command, but in CHO, the UE determines whether to perform handover according to the network pre-configured handover condition, that is, the network does not issue a cell switch command in CHO. If the conditional LTM process is to be supported, how to obtain the TA is a technical problem that needs to be solved urgently.

[0094] If the LTM procedure between CUs is supported, i.e., the LTM procedure occurs between two base stations, when the UE acquires the TA in advance in synchronization at the DU under the target CU, the target DU needs to send the TA to the target CU, the target CU sends the TA to the source CU, and the source CU sends the TA to the source DU. Due to the large transmission delay, the effective time of the TA is shortened. In this scenario, how to maintain the validity of the TA is a technical problem to be solved.

[0095] To solve the above technical problem, the present application provides a communication method. Before the UE determines the target cell and performs the cell switching, the network device informs the UE of the TA of at least one candidate cell, so that the UE acquires the TA in time in the conditional LTM procedure.

[0096] In the following, the technical solutions shown in the present application are described in detail through specific embodiments. It should be noted that the following embodiments can exist independently, or can be combined with each other. For the same or similar content, it is not repeated in different embodiments.

[0097] FIG. 4 is a flowchart of a communication method provided by an embodiment of the present application. As shown in FIG. 4, the method comprises:

[0098] S401, the network device acquires the TA of at least one candidate cell.

[0099] When the network device to which the serving cell belongs and the network device to which the at least one candidate cell belongs are the same network device, the network device determines the TA of the at least one candidate cell, and then performs S402; for any candidate cell, the network device can determine the TA of the candidate cell based on the preamble received from the candidate cell.

[0100] The candidate cell can be a neighboring cell of the serving cell, or a cell preconfigured by the network background. The candidate cell can also be a candidate cell or a candidate neighboring cell.

[0101] When the network device to which the serving cell belongs and the network device to which part of the candidate cells belong are different, part of the candidate cells are part or all of the at least one candidate cell. For any candidate cell in the part of the candidate cells, the network device to which the candidate cell belongs can determine the TA of the candidate cell. The network device to which the candidate cell belongs can perform S402 after determining the TA of the candidate cell, or send the TA of the candidate cell to the network device to which the serving cell belongs, and the network device to which the serving cell belongs performs S402.

[0102] For example, if cell 1 is a cell currently serving the UE, and cell 2, cell 3 and cell 4 are candidate cells, wherein cell 1 and cell 2 belong to network device 1, and cell 3 and cell 4 belong to network device 2, network device 1 can determine the TA of cell 2 and send the TA of cell 2 to the UE; network device 2 can determine the TA of cell 3 and the TA of cell 4 and send the TA of cell 3 and the TA of cell 4 to the UE; or network device 2 can send the TA of cell 3 and the TA of cell 4 to network device 1, and network device 1 can send the TA of cell 3 and the TA of cell 4 to the UE.

[0103] S402, the network device sends the TA of at least one candidate cell to the UE.

[0104] In other words, the UE receives the TA of at least one candidate cell.

[0105] The network device can send the TA of at least one candidate cell from a serving cell, and the UE can receive the TA of at least one candidate cell from the serving cell, i.e., the network device to which the serving cell belongs can send the TA of at least one candidate cell to the UE, and the UE can receive the TA of at least one candidate cell from the network device to which the serving cell belongs.

[0106] The network device sends the TA from at least one candidate cell respectively, and the UE can receive the TA from at least one candidate cell respectively. When the candidate cell is one, the network device to which the candidate cell belongs can send the TA of the candidate cell to the UE, and the UE can receive the TA of the candidate cell from the network device to which the candidate cell belongs; when the candidate cells are multiple and belong to different network devices, the network device to which each candidate cell belongs can send the TA of the corresponding candidate cell to the UE, and the UE can receive the TA of the corresponding candidate cell from the network device to which each candidate cell belongs; when the candidate cells are multiple and belong to the same network device, the network device can send the TA of multiple candidate cells to the UE, and the UE can receive the TA of multiple candidate cells from the network device.

[0107] For example, if cell 1 is a cell currently serving the UE, and cell 2, cell 3 and cell 4 are candidate cells, wherein cell 1 and cell 2 belong to network device 1, and cell 3 and cell 4 belong to network device 2, the UE can receive the TA of cell 2 from network device 1 and the TA of cell 3 and the TA of cell 4 from network device 2; network device 2 can also send the TA of cell 3 and the TA of cell 4 to network device 1, and the UE can receive the TA of cell 2, the TA of cell 3 and the TA of cell 4 from network device 1.

[0108] For any candidate cell, when the UE judges by itself whether it needs to perform early synchronization with the candidate cell, the UE can acquire the TA of the candidate cell in the process of early synchronization with the candidate cell, that is, in the process of early synchronization, the network device to which the candidate cell belongs can send the TA of the candidate cell to the UE through the RAR, or the network device to which the candidate cell belongs can send the TA of the candidate cell to the UE through other layer 1 or layer 2 signaling.

[0109] The UE can autonomously judge whether it needs to perform early synchronization with a candidate cell based on a preconfigured trigger condition of early synchronization of the candidate cell by the network device. For example, when the measurement result of the candidate cell 1 meets a preset condition, the UE autonomously performs early synchronization on the candidate cell 1 to acquire the TA of the candidate cell 1.

[0110] The PDCCH command or other command sent by the network device to which the serving cell belongs can also indicate at least one candidate cell to perform early synchronization according to the existing LTM process, and in this case, the UE can receive the TA of the at least one candidate cell from the serving cell, and the network device to which the serving cell belongs can send the TA of the at least one candidate cell to the UE through a MAC layer message or a physical layer message. For example, the MAC layer message can be a MAC CE; or the UE can perform early synchronization with each candidate cell to acquire the TA of the corresponding candidate cell after receiving the PDCCH command or other command.

[0111] For any candidate cell, if the UE receives the TA of the candidate cell from the network device to which the candidate cell belongs, the UE can directly determine that the TA is valid.

[0112] For any candidate cell, if the UE receives the TA of the candidate cell from the network device to which the serving cell belongs, the UE can directly determine that the TA is valid, or the UE receives a TA validity instruction of the candidate cell sent by the network device to which the serving cell belongs, and determines that the TA of the candidate cell is valid based on the TA validity instruction.

[0113] S403, the UE initiates conditional handover to a first candidate cell in the at least one candidate cell based on the TA of the first candidate cell, and the first candidate cell is a cell in the at least one candidate cell that meets a trigger condition of conditional handover.

[0114] The first candidate cell is a cell in the at least one candidate cell other than the second candidate cell that meets the trigger condition, and the TA of the second candidate cell is invalid.

[0115] The number of the second candidate cells can be one or more, and when the number of the second candidate cells is more than one, the plurality of second candidate cells can belong to the same network device or different network devices.

[0116] In a possible implementation, the UE can receive indication information indicating that the TA of the second candidate cell is invalid.

[0117] The UE can receive indication information from a network device to which the second candidate cell belongs, the indication information indicating that the TA of the second candidate cell is invalid.

[0118] The network device to which the second candidate cell belongs can send the indication information to the UE through a MAC CE.

[0119] The UE can also receive indication information from a network device to which the serving cell belongs, the indication information explicitly indicating that the TA of the second candidate cell is invalid, or implicitly indicating that the TA of the second candidate cell is invalid, when the indication information indicates that the UE re-performs early synchronization with the second candidate cell or re-acquires the TA of the second candidate cell, it means that the TA of the second candidate cell is currently invalid.

[0120] The network device to which the serving cell belongs can send the indication information to the UE through a MAC CE.

[0121] When the TA of the second candidate cell is invalid, the second candidate cell does not participate in the evaluation of the triggering condition of the conditional handover as a target cell, or the second candidate cell can still participate in the evaluation of the triggering condition of the conditional handover, and if the second candidate cell subsequently meets the triggering condition, the UE can perform a random access process to switch to the second candidate cell, and can acquire a valid TA in the random access process.

[0122] The triggering condition of the conditional handover can also be referred to as a handover condition, and the handover condition can be described with reference to the description in Related Art 2, which will not be described here.

[0123] The UE needs to initiate the conditional handover to the network device to which the first candidate cell belongs when the TA of the first candidate cell is valid.

[0124] In the embodiment shown in FIG. 4, before determining the target cell and performing cell handover, the network device informs the UE of the TA of at least one candidate cell, so that the UE can timely acquire the TA in the conditional LTM process. Further, the validity of the TA can be accurately maintained through the TA validity instruction and the indication information indicating the TA invalidity.

[0125] On the basis of the embodiment shown in FIG. 4, the communication method of the present application will be described in detail in combination with FIG. 5.

[0126] FIG. 5 is a flowchart of another communication method provided by an embodiment of the present application. As shown in FIG. 5, the method comprises:

[0127] S501, the network device sends the TA of at least one candidate cell to the UE.

[0128] It should be noted that the execution process of S501 is the same as that of S402, and will not be repeated here. The only thing to note is that before executing S501, the network device needs to obtain the TA of at least one candidate cell. The process of obtaining the TA can be found in the relevant description in S401.

[0129] S502. The effective duration for the network device to send the TAT of the first alternative cell to the UE.

[0130] In other words, the effective duration of the TAT (Time Acquisition Time) of the first alternative cell sent by the network device to the UE.

[0131] The first alternative cell can be a cell that meets the triggering conditions for conditional handover from at least one alternative cell.

[0132] The network device can not only send the validity duration of the TAT of the first alternative cell to the UE, but also send the validity duration of the TAT of other alternative cells to the UE.

[0133] Before sending the valid duration of the TAT of the alternative cell to the UE, the network device can also obtain the valid duration of the TAT of the alternative cell.

[0134] If the network device of the serving cell sends the validity duration of the TAT of a candidate cell to the UE, the network device of the serving cell can either determine the validity duration of the TAT of the candidate cell first, or directly receive the validity duration of the TAT of the candidate cell from the network device of the candidate cell. Alternatively, if the network device of the candidate cell sends the validity duration of the TAT of that candidate cell to the UE, the network device of the candidate cell can determine the validity duration of the TAT of that candidate cell first, and then send it to the UE.

[0135] When sending the TA of at least one alternative cell to the UE, the network device may carry the validity duration of the TAT of the alternative cell.

[0136] For example, for any candidate cell, when the UE determines whether it needs to perform advance synchronization with the candidate cell, the UE can obtain the validity duration of the TA and TAT of the candidate cell during the advance synchronization process. That is, during the advance synchronization process, the network device to which the candidate cell belongs can send the validity duration of the TA and TAT of the candidate cell to the UE through RAR, or the network device to which the candidate cell belongs can send the validity duration of the TA and TAT of the candidate cell to the UE through other Layer 1 or Layer 2 signaling.

[0137] In another example, the UE can also perform early synchronization with the at least one candidate cell according to the existing LTM procedure, and the network device to which the serving cell belongs can indicate the TA and the valid duration of the TAT of the at least one candidate cell to the UE through a PDCCH command or another command. In this case, the UE can receive the TA of the at least one candidate cell from the serving cell, and the network device to which the serving cell belongs can send the TA and the valid duration of the TAT of the at least one candidate cell to the UE through a MAC layer message or a physical layer message. For example, the MAC layer message can be a MAC CE, or the UE can perform early synchronization with each candidate cell to obtain the TA and the valid duration of the TAT of the corresponding candidate cell after receiving the PDCCH command or another command.

[0138] The network device can also send the valid duration of the TAT of the candidate cell to the UE through an RRC reconfiguration message before the UE sends the TA of the candidate cell. In this case, the structure of the RRC reconfiguration message needs to be modified, and the valid duration of the TAT is placed outside the candidate cell configuration information in the RRC reconfiguration message. In the existing LTM procedure, the UE does not parse the candidate cell configuration information (i.e., the RRC reconfiguration message wrapped in a container), and the valid duration of the TAT of the existing candidate cell is included in the candidate cell configuration information. Before determining to perform cell switching on the target cell, the UE does not parse the candidate cell configuration information to obtain the valid duration of the TAT. Now the valid duration of the TAT is placed outside the candidate cell configuration information in the RRC reconfiguration message, so that the UE can obtain the valid duration of the TAT without parsing the candidate cell configuration information in the RRC reconfiguration message after receiving the RRC reconfiguration message.

[0139] Next, the meaning of the valid duration of the TAT is described in detail.

[0140] For any candidate cell, when the duration of the TAT of the candidate cell is indicated to the UE by the serving cell, the valid duration of the TAT of the candidate cell can be the difference between the duration of the TAT indicated by the network device to which the candidate cell belongs to the network device to which the serving cell belongs and a first time delay. The first time delay is the communication duration between the network device to which the first candidate cell belongs and the network device to which the serving cell belongs.

[0141] When the network device includes a DU and a CU, the first time delay can be the communication duration between the CU to which the first candidate cell belongs and the CU to which the serving cell belongs. The first time delay can also be the sum of the communication duration between the CU to which the first candidate cell belongs and the DU to which the first candidate cell belongs, the communication duration between the CU to which the first candidate cell belongs and the CU to which the serving cell belongs, and the communication duration between the CU to which the serving cell belongs and the DU to which the serving cell belongs.

[0142] For example, the DU of the base station 1 sends the duration of the TAT of the candidate cell 1 to the CU of the base station 1, the CU of the base station 1 forwards the duration of the TAT of the candidate cell 1 to the CU of the base station 2, and the CU of the base station 2 forwards the duration of the TAT of the candidate cell 1 to the DU of the base station 2. The base station 2 can subtract the difference between the duration of the TAT of the candidate cell 1 and the duration of the communication between the CU of the base station 1 and the CU of the base station 2 from the duration of the TAT of the candidate cell 1 to obtain the valid duration of the TAT of the candidate cell 1, and then sends the valid duration of the TAT of the candidate cell 1 to the UE.

[0143] In another example, in the LTM preparation process, the network device to which the serving cell belongs obtains the duration of the TAT of the candidate cell 1 in advance when interacting with the network device to which the candidate cell 1 belongs to obtain the candidate cell configuration information of the UE. Subsequently, after the network device to which the candidate cell 1 belongs indicates the TA to the network device to which the serving cell belongs, the serving cell indicates the TA of the candidate cell 1 and the valid duration of the TAT of the candidate cell 1 to the UE. The valid duration of the TAT of the candidate cell 1 is the difference between the duration of the TAT of the candidate cell 1 obtained in the LTM preparation process and the first time delay.

[0144] If the network configures the TAT for the candidate cell, the following describes the starting time of the TAT in detail.

[0145] For any candidate cell, when the network configures the TAT for the candidate cell, the UE starts the TAT of the candidate cell after receiving the TA of the candidate cell sent by the network device to which the candidate cell belongs or receiving the TA validity instruction of the candidate cell sent by the network device to which the serving cell belongs.

[0146] For any candidate cell, if the network side configures the TA and the TAT for the candidate cell, the TA of the candidate cell is valid within the running period of the TAT of the candidate cell, and the valid duration of the TAT of the candidate cell can be the running duration of the TAT of the candidate cell. If the TAT of the candidate cell expires, the TA of the candidate cell is invalid.

[0147] S503, the UE initiates the conditional handover to the first candidate cell based on the TA of the first candidate cell.

[0148] If the TAT of the first candidate cell expires, the TA of the first candidate cell is invalid, and if the first candidate cell meets the trigger condition of the conditional handover, the UE can initiate the random access to the first candidate cell to obtain a valid TA. The completion of the random access process indicates that the UE successfully switches to the first candidate cell.

[0149] In the embodiment shown in FIG. 5, before determining the target cell and performing the cell switching, the network device informs the UE of the TA of at least one candidate cell and the validity duration of the TAT of part of the candidate cells, so that the UE can accurately maintain the validity of the TA.

[0150] For the convenience of understanding, the following examples are given to illustrate the process of the present application in detail.

[0151] Example 1

[0152] S1, the network device to which the serving cell belongs sends a PDCCH command to the UE to trigger the early synchronization process.

[0153] S2, the UE initiates early synchronization with the network device to which candidate cell 1 belongs, the network device to which candidate cell 2 belongs and the network device to which candidate cell 3 belongs, respectively, so that the network device to which candidate cell 1 belongs determines the TA of candidate cell 1, the network device to which candidate cell 2 belongs determines the TA of candidate cell 2, and the network device to which candidate cell 3 belongs determines the TA of candidate cell 3.

[0154] S3, the network device to which candidate cell 1 belongs sends the TA of candidate cell 1 to the network device to which the serving cell belongs, the network device to which candidate cell 2 belongs sends the TA of candidate cell 2 to the network device to which the serving cell belongs, and the network device to which candidate cell 3 belongs sends the TA of candidate cell 3 to the network device to which the serving cell belongs.

[0155] S4, the network device to which the serving cell belongs can send the TAs of the three candidate cells to the UE through a MAC CE.

[0156] In S4, the UE can determine that the TAs of the three candidate cells are valid when receiving the TAs of the three candidate cells, or the UE can determine that the TAs of the three candidate cells are valid when receiving the TA validity instruction sent by the network device to which the serving cell belongs, the TA validity instruction indicating that the TAs of the three candidate cells are valid.

[0157] For any candidate cell, if the network side does not configure a TAT for the candidate cell, the network device to which the serving cell belongs can send indication information to the UE when determining that the TA of the candidate cell is invalid, the indication information indicating that the TA of the candidate cell is invalid; the UE can re-perform early synchronization to obtain the valid TA of the candidate cell based on the indication information, or the UE can further determine whether the candidate cell meets the trigger condition of early synchronization, and if the trigger condition of early synchronization is met, the UE can re-perform early synchronization with the candidate cell to obtain the valid TA of the candidate cell.

[0158] Example 2,

[0159] S1, the UE receives the preconfigured trigger condition of the early synchronization of the candidate cell 1, the candidate cell 2 and the candidate cell 3 of the network device to which the serving cell belongs.

[0160] S2, for the candidate cell 1, if the UE meets the trigger condition of the early synchronization of the candidate cell 1, the UE can obtain the TA of the candidate cell 1 through the early synchronization, that is, the UE can receive the RAR sent by the network device to which the candidate cell 1 belongs, and the RAR carries the TA of the candidate cell 1.

[0161] The UE can obtain the TA of the candidate cell 2 and the TA of the candidate cell 3 through the same way.

[0162] For S2, the UE can determine that the TA of the candidate cell 1 is valid when the TA of the candidate cell 1 is received.

[0163] If the network side does not configure the TAT for the candidate cell 1, the network device to which the candidate cell 1 belongs can send indication information to the UE when it is determined that the TA of the candidate cell 1 is invalid, the indication information indicates that the TA of the candidate cell 1 is invalid; the UE can re-perform early synchronization based on the indication information to obtain the valid TA of the candidate cell 1, or the UE can further determine whether the candidate cell 1 meets the trigger condition of the early synchronization, if the trigger condition of the early synchronization is met, the UE can re-perform early synchronization with the candidate cell 1 to obtain the valid TA of the candidate cell 1.

[0164] Example 3,

[0165] S1, the network device to which the serving cell belongs sends the PDCCH command to the UE to trigger the early synchronization process.

[0166] S2, the UE initiates early synchronization to the network device to which the candidate cell 1 belongs to obtain the TA of the candidate cell 1; the UE initiates early synchronization to the network device to which the candidate cell 2 belongs to obtain the TA of the candidate cell 21; the UE initiates early synchronization to the network device to which the candidate cell 3 belongs to obtain the TA of the candidate cell 3.

[0167] For S2, the UE can determine that the TAs of the three candidate cells are valid when the TAs of the three candidate cells are received.

[0168] For any candidate cell, if the network side does not configure TAT for the candidate cell, the network device to which the candidate cell belongs can send indication information to the UE when determining that the TA of the candidate cell is invalid, and the indication information indicates that the TA of the candidate cell is invalid; the UE can re-perform early synchronization based on the indication information to obtain the valid TA of the candidate cell, or the UE can further determine whether the candidate cell meets the trigger condition of early synchronization, and if the trigger condition of early synchronization is met, the UE can re-perform early synchronization with the candidate cell to obtain the valid TA of the candidate cell.

[0169] Example 4,

[0170] S1, the network device to which the serving cell belongs sends a PDCCH command to the UE to trigger the early synchronization process.

[0171] S2, the UE initiates early synchronization with the network device to which the candidate cell 1 belongs, the network device to which the candidate cell 2 belongs, and the network device to which the candidate cell 3 belongs, respectively, so that the network device to which the candidate cell 1 belongs determines the TA and the time length of TAT of the candidate cell 1, the network device to which the candidate cell 2 belongs determines the TA and the time length of TAT of the candidate cell 2, and the network device to which the candidate cell 3 belongs determines the TA and the time length of TAT of the candidate cell 3.

[0172] S3, the network device to which the candidate cell 1 belongs sends the TA and the time length of TAT of the candidate cell 1 to the network device to which the serving cell belongs, the network device to which the candidate cell 2 belongs sends the TA and the time length of TAT of the candidate cell 2 to the network device to which the serving cell belongs, and the network device to which the candidate cell 3 belongs sends the TA and the time length of TAT of the candidate cell 3 to the network device to which the serving cell belongs.

[0173] In S3, for any candidate cell, if the network device to which the candidate cell belongs is different from the network device to which the serving cell belongs, after receiving the time length of TAT of the candidate cell, the network device to which the serving cell belongs needs to subtract the communication time length between the network device to which the candidate cell belongs and the network device to which the serving cell belongs from the time length of TAT of the candidate cell to obtain the valid time length of TAT of the candidate cell.

[0174] S4, the network device to which the serving cell belongs can send the TA and the valid time length of TAT of the three candidate cells to the UE through MAC CE.

[0175] In S4, the UE can start the TAT corresponding to the three candidate cells when receiving the TA of the three candidate cells. The UE can also start the TAT of the candidate cell 1 when receiving the TA validity instruction of the candidate cell 1 sent by the network device to which the serving cell belongs.

[0176] The TA of the alternative cell is valid within a running period of the TAT of the alternative cell.

[0177] When the TAT of the alternative cell expires, the TA of the alternative cell is invalid, or the TA of the alternative cell is invalid when indication information indicating that the TA of the alternative cell is invalid is received within the running period of the TAT of the alternative cell, the indication information being sent by a network device to which the serving cell belongs; the UE can re-perform early synchronization to obtain a valid TA of the alternative cell based on the indication information, and optionally, a valid time length of the TAT; or the UE can further determine whether the alternative cell satisfies a trigger condition of early synchronization, and if the trigger condition of early synchronization is satisfied, the UE can re-perform early synchronization with the alternative cell to obtain a valid TA of the alternative cell, and optionally, a valid time length of the TAT.

[0178] One or more beam information can also be carried in the MAC CE, and the beam information can be identified by a target configuration ID to which the alternative cell belongs.

[0179] Example 5,

[0180] S1, the UE receives preconfigured early synchronization trigger conditions of alternative cell 1, alternative cell 2, and alternative cell 3 of a network device to which the serving cell belongs.

[0181] S2, for alternative cell 1, if the UE satisfies the early synchronization trigger condition of alternative cell 1, the UE can obtain a TA of alternative cell 1 and a valid time length of the TAT of alternative cell 1 through early synchronization, that is, the UE can receive a RAR sent by a network device to which alternative cell 1 belongs, the RAR carrying the TA of alternative cell 1 and the valid time length of the TAT of alternative cell 1.

[0182] The UE can obtain the TA of alternative cell 2 and the valid time length of the TAT of alternative cell 2, and the TA of alternative cell 3 and the valid time length of the TAT of alternative cell 3 in the same way.

[0183] For S2, the UE can start the TAT of alternative cell 1 when the TA of alternative cell 1 is received.

[0184] Within the running period of the TAT of alternative cell 1, the TA of alternative cell 1 is valid.

[0185] When the TAT of alternative cell 1 expires, the TA of alternative cell 1 is invalid, or the TA of alternative cell 1 is invalid when indication information indicating that the TA of alternative cell 1 is invalid is received within the running period of the TAT of alternative cell 1, the indication information being sent by a network device to which the alternative cell belongs; the alternative cell 1 can re-obtain a valid TA of alternative cell 1 through early synchronization when the trigger condition of early synchronization is satisfied, and optionally, a valid time length of the TAT.

[0186] Example 6,

[0187] S1, the network device to which the serving cell belongs sends an RRC reconfiguration message to the UE, and the RRC reconfiguration message carries the time length of the TAT of the candidate cell 1, the time length of the TAT of the candidate cell 2, and the time length of the TAT of the candidate cell 3. The time lengths of the TATs of the three candidate cells are carried in an outer layer of the RRC reconfiguration message, so that the UE can obtain the time lengths of the TATs of the three candidate cells without parsing the RRC reconfiguration message after receiving the RRC reconfiguration message.

[0188] If the network device to which the serving cell belongs is the same as the network device to which the candidate cell belongs, the time lengths of the TATs of the three candidate cells are valid time lengths, and if the network device to which the serving cell belongs is different from the network device to which the candidate cell belongs, the time lengths of the TATs of the three candidate cells are invalid time lengths.

[0189] The subsequent steps can be the same as S1 to S4 in Example 1, or the same as S1 to S2 in Example 2, or the same as S1 to S2 in Example 3. When the TAT is started and the validity of the TA is determined, refer to the related description in Example 3 and Example 4, which will not be repeated here.

[0190] On the basis of any of the above examples, if the TA of the candidate cell 1 is valid, the TA of the candidate cell 2 is valid, and the TA of the candidate cell 3 is invalid. The candidate cell 3 can not participate in the trigger condition of the conditional handover as a target cell. In this case, if the candidate cell 1 meets the trigger condition of the conditional handover, the UE can initiate the conditional handover to the network device to which the candidate cell 1 belongs, and the UE considers that the handover is completed when the network device receives the first uplink data. The three candidate cells can all participate in the trigger condition of the conditional handover as target cells. In this case, if the candidate cell 3 meets the trigger condition of the conditional handover, the UE can initiate random access to the network device to which the candidate cell 3 belongs to obtain a valid TA, and the UE considers that the handover is completed when the random access is completed.

[0191] FIG. 6 is a structural schematic diagram of a communication apparatus provided by an embodiment of the present application. As shown in FIG. 6, the apparatus 10 includes:

[0192] The receiving module 11 is configured to receive the TA of at least one candidate cell.

[0193] The processing module 12 is configured to initiate the conditional handover to a first candidate cell based on the TA of the first candidate cell in the at least one candidate cell, and the first candidate cell is a cell in the at least one candidate cell that meets the trigger condition of the conditional handover.

[0194] In a possible implementation, the receiving module 11 is specifically configured to:

[0195] receiving the TA of the at least one candidate cell from the serving cell; or

[0196] receiving the TA of the at least one candidate cell from the at least one candidate cell respectively.

[0197] In a possible implementation, the receiving module 11 is further configured to:

[0198] receive a TA validation instruction of the first candidate cell sent from the serving cell, the TA validation instruction indicating that the TA of the first candidate cell is valid.

[0199] In a possible implementation, the TA of the first candidate cell is valid within a running period of a time alignment timer TAT of the first candidate cell, and a valid duration of the TAT of the first candidate cell is a running duration of the TAT of the first candidate cell.

[0200] In a possible implementation, the receiving module 11 is further configured to:

[0201] receive the valid duration of the TAT of the first candidate cell.

[0202] In a possible implementation, the valid duration of the TAT of the first candidate cell is a difference between a duration of the TAT of the first candidate cell indicated to the serving cell by the first candidate cell and a first delay, the first delay being a communication duration between the first candidate cell and the serving cell.

[0203] In a possible implementation, the receiving module 11 is further configured to:

[0204] start the TAT of the first candidate cell upon receiving the TA sent by the first candidate cell; or

[0205] start the TAT of the first candidate cell upon receiving the TA validation instruction of the first candidate cell sent by the serving cell.

[0206] In a possible implementation, the first candidate cell is a cell that meets a trigger condition among the at least one candidate cell except for a second candidate cell, and the TA of the second candidate cell is invalid.

[0207] In a possible implementation, the receiving module 11 is further configured to:

[0208] receive indication information, the indication information indicating that the TA of the second candidate cell is invalid.

[0209] In a possible implementation, the TA of the second candidate cell is invalid, including that a TAT of the second candidate cell is overdue.

[0210] In a possible implementation, the apparatus 10 further includes a sending module 13 configured to:

[0211] If the TA of the first candidate cell is invalid, and the first candidate cell satisfies the triggering condition of the handover, the random access is initiated to the first candidate cell.

[0212] The communication device 10 can perform the steps executed by the UE in the method embodiments described above, and the implementation principles and beneficial effects are similar, which will not be described here again.

[0213] FIG. 7 is a structural schematic diagram of another communication device provided by an embodiment of the present application. As shown in FIG. 7, the device 20 includes:

[0214] The processing module 21 is configured to acquire the TA of at least one candidate cell.

[0215] The sending module 22 is configured to send the TA of the at least one candidate cell.

[0216] In a possible implementation, the sending module 22 is specifically configured to:

[0217] send the TA of the at least one candidate cell from the serving cell; or

[0218] send the timing advance TA from the at least one candidate cell respectively.

[0219] In a possible implementation, the sending module 22 is further configured to:

[0220] send a TA validity instruction of the first candidate cell from the serving cell, the TA validity instruction indicating that the TA of the first candidate cell is valid.

[0221] In a possible implementation, the TA of the first candidate cell is valid within a running period of a time alignment timer TAT of the first candidate cell, and the valid time length of the TAT of the first candidate cell is a running time length of the TAT of the first candidate cell.

[0222] In a possible implementation, the sending module 22 is further configured to:

[0223] send the valid time length of the TAT of the first candidate cell.

[0224] In a possible implementation, the valid time length of the TAT of the first candidate cell is a difference between a time length of the TAT of the first candidate cell indicated to the serving cell and a first time delay, and the first time delay is a communication time length between the first candidate cell and the serving cell.

[0225] In a possible implementation, the first candidate cell is a cell satisfying the triggering condition in the at least one candidate cell except for a second candidate cell, and the TA of the second candidate cell is invalid.

[0226] In a possible implementation, the sending module 22 is further configured to:

[0227] The sending indication information indicates that the TA of the second candidate cell is invalid, and the second candidate cell is a cell other than the first candidate cell in the at least one candidate cell.

[0228] The communication apparatus 20 can perform the steps performed by the network device in the method embodiments described above, and the implementation principle and beneficial effects are similar, and thus will not be described here in detail.

[0229] FIG. 8 is a structural schematic diagram of another communication apparatus provided by an embodiment of the present application. Referring to FIG. 8, the communication apparatus 30 can include a transceiver 31, a memory 32, and a processor 33. The transceiver 31 can include a transmitter and / or a receiver. The transmitter can also be referred to as a sender, a transmitter, a sending port, a sending interface, or the like. The receiver can also be referred to as a receiver, a receiver, a receiving port, a receiving interface, or the like. Exemplarily, the transceiver 31, the memory 32, and the processor 33 are connected to each other through a bus 34.

[0230] The memory 32 is configured to store program instructions.

[0231] The processor 33 is configured to execute the program instructions stored in the memory, so as to enable the communication apparatus 30 to perform the steps performed by the UE or the steps performed by the network device in the method embodiments described above.

[0232] The transceiver 31 is configured to perform the transceiving functions of the communication apparatus 30 in the communication method described above.

[0233] The communication apparatus 30 can be a chip, a module, an integrated development environment (IDE), or the like.

[0234] The communication apparatus 30 can perform the steps performed by the UE or the steps performed by the network device in the method embodiments described above, and the implementation principle and beneficial effects are similar, and thus will not be described here in detail.

[0235] An embodiment of the present application provides a computer-readable storage medium, which stores computer-executable instructions. When the computer-executable instructions are executed by a computer, any one of the communication methods described above is performed.

[0236] An embodiment of the present application further provides a computer program product, which can be executed by a processor. When the computer program product is executed by the computer, any one of the communication methods described above is performed.

[0237] All or a part of the steps of each method embodiment described above can be completed by program instruction related hardware. The aforementioned program can be stored in a readable memory. The program, when executed, performs steps including the aforementioned method embodiments; and the aforementioned memory (storage medium) includes: Read Only Memory (ROM), Random Access Memory (RAM), flash memory, hard disk, solid state disk, magnetic tape, floppy disk, optical disc, and any combination thereof.

[0238] The embodiments of the present application are described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and a combination of flows and / or blocks in the flowcharts and / or block diagrams can be implemented by computer program instructions. These computer program instructions can be provided to a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to produce a machine, so that the instructions executed by the computer or other programmable data processing devices produce a device that implements the functions specified in one or more flows in the flowcharts and / or one or more blocks in the block diagrams.

[0239] These computer program instructions can also be stored in a computer readable memory that can direct the computer or other programmable data processing devices to work in a specific manner, so that the instructions stored in the computer readable memory produce a manufactured product including instruction devices that implement the functions specified in one or more flows in the flowcharts and / or one or more blocks in the block diagrams.

[0240] These computer program instructions can also be loaded into a computer or other programmable data processing device, so that a series of operation steps are performed on the computer or other programmable device to produce a computer implemented process, so that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more flows in the flowcharts and / or one or more blocks in the block diagrams.

[0241] Obviously, those skilled in the art can make various modifications and variations to the embodiments of the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the embodiments of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and variations.

Claims

1. A communication method characterized by comprising: The method comprises: receiving timing advance (TA) of at least one candidate cell; initiating conditional handover to a first candidate cell among the at least one candidate cell based on TA of the first candidate cell satisfying a triggering condition of conditional handover.

2. The method of claim 1, wherein, The receiving TA of the at least one candidate cell comprises: receiving TA of the at least one candidate cell from a serving cell; or receiving timing advance (TA) of the at least one candidate cell respectively from the at least one candidate cell.

3. The method according to claim 1 or 2, characterized in that, The method further comprises: receiving TA validity instruction of the first candidate cell sent by the serving cell, the TA validity instruction indicating that TA of the first candidate cell is valid.

4. The method according to claim 1 or 2, characterized in that, The TA of the first candidate cell is valid within a running period of time alignment timer (TAT) of the first candidate cell, and a valid duration of the TAT of the first candidate cell is a difference between a duration of TAT of the first candidate cell indicated to the serving cell and a first delay, the first delay being a communication duration between the first candidate cell and the serving cell.

5. The method of claim 4, wherein, The method further comprises: receiving the valid duration of the TAT of the first candidate cell.

6. The method according to claim 4 or 5, characterized in that, The valid duration of the TAT of the first candidate cell is the difference between the duration of TAT of the first candidate cell indicated to the serving cell and the first delay, the first delay being the communication duration between the first candidate cell and the serving cell.

7. The method according to any one of claims 4-6, characterized in that, The method further comprises: starting the TAT of the first candidate cell upon receiving TA sent by the first candidate cell; or starting the TAT of the first candidate cell upon receiving TA validity instruction of the first candidate cell sent by the serving cell.

8. The method of claim 1, wherein, The first candidate cell is a cell among the at least one candidate cell other than a second candidate cell, and the second candidate cell has TA invalidation.

9. The method of claim 8, wherein, The method further comprises: receiving indication information indicating TA invalidation of the second candidate cell.

10. The method of claim 8, wherein, The TA invalidation of the second candidate cell comprises: the TAT of the second candidate cell expires.

11. The method of claim 4, wherein, The method further comprises: initiating random access to the first candidate cell if TA of the first candidate cell is invalid and the first candidate cell satisfies the triggering condition of conditional handover.

12. A communication method characterized by comprising: The method comprises: obtaining timing advance (TA) of at least one candidate cell; sending TA of the at least one candidate cell.

13. The method of claim 12, wherein, The sending TA of the at least one candidate cell comprises: sending TA of the at least one candidate cell from a serving cell; or sending timing advance (TA) of the at least one candidate cell respectively from the at least one candidate cell.

14. The method of claim 13, wherein, The method further comprises: sending TA validity instruction of the first candidate cell from the serving cell, the TA validity instruction indicating that TA of the first candidate cell is valid.

15. The method according to claim 12 or 13, characterized in that, The TA of the first candidate cell is valid within a running period of time alignment timer (TAT) of the first candidate cell, and a valid duration of the TAT of the first candidate cell is a duration of TAT of the first candidate cell.

16. The method of claim 15, wherein, The method further comprises: sending the valid duration of the TAT of the first candidate cell.

17. The method according to claim 15 or 16, characterized in that, The valid duration of the TAT of the first candidate cell is a difference between a duration of the TAT indicated by the first candidate cell to a serving cell and a first delay, the first delay being a duration of communication between the first candidate cell and the serving cell.

18. The method of claim 12, wherein, The first candidate cell is a cell in the at least one candidate cell other than a second candidate cell, the TA of the second candidate cell being invalid.

19. The method of claim 18, wherein, The method further comprises: sending indication information, the indication information indicating that the TA of a second candidate cell is invalid, the second candidate cell being a cell in the at least one candidate cell other than the first candidate cell.

20. A communications device, characterized by comprising a receiving module and a processing module, wherein, the receiving module is configured to receive a timing advance (TA) of at least one candidate cell; the processing module is configured to initiate a conditional handover to a first candidate cell in the at least one candidate cell based on a TA of the first candidate cell, the first candidate cell being a cell in the at least one candidate cell satisfying a triggering condition of conditional handover.

21. A communications device, characterized by comprising a processing module and a sending module, wherein, the processing module is configured to obtain a timing advance (TA) of at least one candidate cell; the sending module is configured to send the TA of the at least one candidate cell.

22. A communications device, characterized by comprising: a processor, and a memory connected to the processor in communication; the memory stores computer-executable instructions; the processor executes the computer-executable instructions stored in the memory to implement the method of any one of claims 1-11, or the method of any one of claims 12-19.

23. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, and the computer-executable instructions are executed by the processor to implement the method of any one of claims 1-11, or the method of any one of claims 12-19.

24. A computer program product, characterised in that, The computer program is executed by the processor to implement the method of any one of claims 1-11, or the method of any one of claims 12-19.

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