Communication method and device and storage medium

Abstract

The embodiment of the invention provides a communication method and device and a storage medium, and belongs to the technical field of communication. In the method, UE receives a TA of at least one alternative cell and initiates condition switching to a first alternative cell in the at least one alternative cell based on the TA of the first alternative cell, and the first alternative cell is a cell meeting a triggering condition of the condition switching in the at least one alternative cell. Before the target cell is determined and cell switching is executed, the network device informs the UE of the TA of the at least one alternative cell, so that the UE obtains the TA in time in the conditional LTM process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of communication, and particularly relates to a communication method, device and storage medium. BACKGROUND

[0002] In some cases, for example, when the cell environment where the user equipment (UE) is currently located deteriorates, the UE needs to be handed over.

[0003] In the related art, the cell handover can be performed through a layer 1 / 2 triggered mobility (LTM) process. In the LTM process, a network device provides configuration information of one or more candidate cells for a UE based on a measurement report (for example, 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 (for example, a layer 1 measurement report) to the network device, and a distributed unit (DU) of the network device decides to trigger the LTM handover based on the measurement report reported by the UE; the original DU sends an LTM cell handover command to the UE through layer 1 signaling and / or layer 2 signaling, so that the UE performs a handover process based on an indication in the handover command, and the handover command can include a time advance (TA).

[0004] In a conditional handover (CHO) process, the UE determines whether to perform handover according to a handover condition pre-configured by the network device, that is, in the CHO process, the network device does not send a handover command to the UE, and if the conditional LTM process is to be supported, how to obtain the TA is a technical problem to be solved urgently. SUMMARY

[0005] The present application relates to a communication method, device and storage medium, and provides a method for obtaining a TA in a conditional LTM process.

[0006] In a first aspect, an embodiment of the present application provides a communication method, comprising:

[0007] receiving a time advance (TA) of at least one candidate cell;

[0008] initiating conditional handover to a first candidate cell in the at least one candidate cell based on the TA of the first candidate cell, the first candidate cell being a cell in the at least one candidate cell that meets a trigger condition of the conditional handover.

[0009] In a possible implementation, the receiving the TA of the at least one candidate cell comprises: receiving the TA of the at least one candidate cell through layer 1 signaling and / or layer 2 signaling.

[0010] receiving, from the serving cell, a TA of the at least one candidate cell; or

[0011] receiving, from the at least one candidate cell respectively, a timing advance TA.

[0012] In a possible implementation, the method further includes:

[0013] 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.

[0014] In a possible implementation, the TA of the first candidate cell is valid within a runtime period of a TAT of the first candidate cell, and a valid duration of the TAT of the first candidate cell is a runtime duration of the TAT of the first candidate cell.

[0015] In a possible implementation, the method further includes:

[0016] receiving a valid duration of the TAT of the first candidate cell.

[0017] 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 and a first delay, and the first delay is a communication duration between the first candidate cell and the serving cell.

[0018] In a possible implementation, the method further includes:

[0019] starting the TAT of the first candidate cell upon receiving a TA sent by the first candidate cell; or

[0020] starting the TAT of the first candidate cell upon receiving a TA validation instruction of the first candidate cell sent by the serving cell.

[0021] In a possible implementation, the first candidate cell is a cell that meets the 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.

[0022] In a possible implementation, the method further includes:

[0023] receiving indication information, the indication information indicating that the TA of the second candidate cell is invalid.

[0024] In a possible implementation, the TA of the second candidate cell is invalid, including:

[0025] TAT expiry of the second candidate cell.

[0026] In a possible implementation, the method further includes:

[0027] if the TA of the first candidate cell is invalid, and the first candidate cell satisfies the triggering condition of conditional handover, initiating random access to the first candidate cell.

[0028] In a second aspect, an embodiment of the present application provides a communication method, including:

[0029] obtaining timing advance (TA) of at least one candidate cell;

[0030] sending the TA of the at least one candidate cell.

[0031] In a possible implementation, the sending the TA of the at least one candidate cell includes:

[0032] sending the TA of the at least one candidate cell from a serving cell; or

[0033] sending the TA of the at least one candidate cell from the at least one candidate cell respectively.

[0034] In a possible implementation, the method further includes:

[0035] sending 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.

[0036] 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.

[0037] In a possible implementation, the method further includes:

[0038] sending a valid duration of the TAT of the first candidate cell.

[0039] 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 and a first delay, and the first delay is a communication duration between the first candidate cell and the serving cell.

[0040] 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.

[0041] In a possible implementation, the method further includes:

[0042] sending indication information, the indication information indicating that the TA of the second candidate cell is invalid, the second candidate cell being a cell other than the first candidate cell in the at least one candidate cell.

[0043] In a third aspect, an embodiment of the present application provides a communication apparatus, including a receiving module and a processing module, wherein,

[0044] the receiving module is configured to receive timing advance (TA) of at least one candidate cell;

[0045] the processing module is configured to initiate conditional handover to a first candidate cell in the at least one candidate cell based on TA of the first candidate cell, the first candidate cell being a cell in the at least one candidate cell that meets a trigger condition of conditional handover.

[0046] In a fourth aspect, an embodiment of the present application provides a communication apparatus, including a processing module and a sending module, wherein,

[0047] the processing module is configured to acquire timing advance (TA) of at least one candidate cell;

[0048] the sending module is configured to send the TA of the at least one candidate cell.

[0049] 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;

[0050] the memory stores computer-executed instructions;

[0051] the processor executes the computer-executed instructions stored in the memory, so that the processor executes the method in the first aspect or the second aspect.

[0052] In a sixth aspect, an embodiment of the present application provides a computer-readable storage medium, the computer-readable storage medium storing computer-executed instructions, when the computer-executed instructions are executed by a processor, the computer-executed instructions being used to implement the method in the first aspect or the second aspect.

[0053] In a seventh aspect, an embodiment of the present application provides a computer program product, including a computer program, when the computer program is executed by a processor, the computer program implementing the method in the first aspect or the second aspect.

[0054] In an eighth aspect, an embodiment of the present application provides a chip, the chip storing a computer program, when the computer program is executed by the chip, the computer program implementing the method in the first aspect or the second aspect.

[0055] In a possible implementation, the chip is a chip in a chip module.

[0056] The embodiment of the present application provides a communication method, device and storage medium. In the method, a UE receives TAs of at least one candidate cell, initiates 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 a trigger condition of the 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

[0057] 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.

[0058] Figure 1 A flowchart of a cell handover process in the related art is shown;

[0059] Figure 2 A flowchart of a conditional handover process in the related art is shown;

[0060] Figure 3 A flowchart of an LTM handover process in the related art is shown;

[0061] Figure 4 A flowchart of a communication method provided by the embodiment of the present application is shown;

[0062] Figure 5 A flowchart of another communication method provided by the embodiment of the present application is shown;

[0063] Figure 6 A structural diagram of a communication device provided by the embodiment of the present application is shown;

[0064] Figure 7 A structural diagram of another communication device provided by the embodiment of the present application is shown;

[0065] Figure 8 A structural diagram of still another communication device provided by the embodiment of the present application is shown.

[0066] The above-described drawings have shown the specific embodiments of the present application, and the following will have a more detailed description. The drawings and the text description are not intended to limit the scope of the concept of the present application by any means, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0067] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will be combined with the accompanying drawings for the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0068] In the embodiments of the present application, the term "at least one" means one or more. "Multiple" means two or more.

[0069] 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 relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. The character " / " generally represents that the associated objects before and after it are in an "or" relationship.

[0070] The first, second, and the like appearing in the embodiments of the present application are only for indicating and distinguishing the described objects, and there is no order, nor represent a special limitation on the number of objects in the embodiments of the present application, and 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.

[0071] In the embodiments of the present application, "for example", "in some embodiments", "in other embodiments", and the like are used to represent as an example, illustration or description. 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. In fact, the word "example" is intended to present the concept in a specific way.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] In order to more clearly illustrate the present application, first, the related art related to the present application will be introduced.

[0077] 1. Cell handover

[0078] 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.

[0079] The flow of cell handover is as follows Figure 1As shown, 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 for handover according to the measurement result of the UE, and then sends a handover command to the UE to initiate a handover process. In step 8, the UE accesses the target cell through a 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 a 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, ∞}.

[0080] 2. Conditional handover (CHO)

[0081] 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, Figure 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 a 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 a random access process and start the corresponding TAT.

[0082] 3. Layer 1 / 2 triggered mobility (LTM) procedure

[0083] In the LTM procedure, the network side can instruct the UE to perform cell switching based on the layer 1 measurement results reported by the UE using layer 2 signaling (medium access control (MAC) control element (CE)) to reduce the switching delay.

[0084] 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.

[0085] As shown in FIG. 1, the LTM procedure includes the following four parts: Figure 3

[0086] (1) LTM preparation: The network side provides the UE with configuration information of one or more candidate cells according to the measurement results reported by the UE.

[0087] (2) Advance synchronization: The network side can require the UE to perform advance synchronization with 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.

[0088] ​(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.

[0089] 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.

[0090] 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.

[0091] (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.

[0092] 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.

[0093] If the LTM procedure between CUs is supported in the future, i.e., the LTM procedure occurs between two base stations, when the UE acquires the TA in advance in synchronization under the DU of 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.

[0094] To solve the above technical problems, the present application provides a communication method. Before the UE determines the target cell and performs 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.

[0095] In the following, the technical solutions shown in the present application will be 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 will not be repeated in different embodiments.

[0096] Figure 4 A flowchart of a communication method provided by an embodiment of the present application is shown in FIG. 1. As shown in FIG. 1, the method comprises the following steps. Figure 4

[0097] S401, the network device acquires the TA of at least one candidate cell.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] ​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.

[0102] S402, the network device sends the TA of at least one candidate cell to the UE.

[0103] In other words, the UE receives the TA of at least one candidate cell.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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. 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.

[0109] 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, in which case, the UE can receive the TA of at least one candidate cell from the serving cell, and the network device to which the serving cell belongs can send the TA of 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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.

[0114] The number of second candidate cells can be one or more, and when the number of second candidate cells is more than one, the plurality of second candidate cells can belong to the same network device or different network devices.

[0115] In one possible implementation, the UE may receive indication information indicating that the TA of the second alternative cell has failed.

[0116] The UE can receive indication information from the network equipment to which the second alternative cell belongs, indicating that the TA of the second alternative cell has failed.

[0117] The network equipment belonging to the second alternative cell can send indication information to the UE via MAC CE.

[0118] The UE can also receive indication information from the network equipment to which the serving cell belongs. The indication information can explicitly indicate that the TA of the second alternative cell has failed, or it can implicitly indicate that the TA of the second alternative cell has failed. When the indication information indicates that the second alternative cell should resynchronize in advance or reacquire the TA of the second alternative cell, it indicates that the current TA of the second alternative cell has failed.

[0119] The network equipment belonging to the serving cell can send indication information to the UE via MAC CE.

[0120] When the TA of the second alternative cell fails, the second alternative cell will not be used as the target cell to participate in the evaluation of the trigger condition for handover. Alternatively, the second alternative cell can still participate in the evaluation of the trigger condition for handover. If the second alternative cell subsequently meets the trigger condition, the user can handover to the second alternative cell through a random access procedure and obtain a valid TA during the random access procedure.

[0121] The triggering condition for condition switching can also be called the switching condition. The switching condition can be referred to in the description in related technology 2, which will not be repeated here.

[0122] The UE needs to initiate a conditional handover to the network device to which the first alternative cell belongs when the TA of the first alternative cell is valid.

[0123] exist Figure 4 In the illustrated embodiment, before determining the target cell and performing cell handover, the network device informs the UE of the TA (Target Acquisition Message) of at least one candidate cell, so that the UE can obtain the TA in a timely manner during the Conditional LTM (Low-Terminal Mechanism) process. Furthermore, the validity of the TA can be accurately maintained through TA activation commands and indications indicating TA failure.

[0124] exist Figure 4 Based on the illustrated embodiment, the following is combined with Figure 5 The communication method described in this application is explained in detail.

[0125] Figure 5 This is a flowchart illustrating another communication method provided in an embodiment of this application. Figure 5 As shown, the method includes:

[0126] S501, the network device sends the TA of the at least one candidate cell to the UE.

[0127] It should be noted that the execution process of S501 can refer to the execution process of S402, which will not be described here. The only thing that needs to be explained is that the network device needs to obtain the TA of the at least one candidate cell before executing S501. The process of obtaining can refer to the related description in S401.

[0128] S502, the network device sends the valid duration of the TAT of the first candidate cell to the UE.

[0129] In other words, the UE receives the valid duration of the TAT of the first candidate cell sent by the network device.

[0130] The first candidate cell can be a cell in the at least one candidate cell that meets the triggering condition of the conditional handover.

[0131] The network device can not only send the valid duration of the TAT of the first candidate cell to the UE, but also send the valid duration of the TAT of other candidate cells to the UE.

[0132] The network device can obtain the valid duration of the TAT of the candidate cell before sending it to the UE.

[0133] If the network device to which the serving cell belongs sends the valid duration of the TAT of the candidate cell to the UE, the network device to which the serving cell belongs can first determine the valid duration of the TAT of the candidate cell, or directly receive the valid duration of the TAT of the candidate cell from the network device to which the candidate cell belongs. If the network device to which the candidate cell belongs sends the valid duration of the TAT of the candidate cell to the UE, the network device to which the candidate cell belongs can first determine the valid duration of the TAT of the candidate cell, and then send it to the UE.

[0134] The network device can carry the valid duration of the TAT of the candidate cell when sending the TA of the at least one candidate cell to the UE.

[0135] For example, for any candidate cell, when the UE itself judges whether it needs to perform early synchronization with the candidate cell, the UE can obtain the TA and the valid duration of the TAT of the candidate cell in the process of performing 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 and the valid duration of the TAT of the candidate cell to the UE through RAR, or the network device to which the candidate cell belongs can send the TA and the valid duration of the TAT of the candidate cell to the UE through other layer 1 or layer 2 signaling.

[0136] 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 validity 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 validity 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 validity duration of the TAT of the corresponding candidate cell after receiving the PDCCH command or another command.

[0137] The network device can also send the validity 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 validity 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 existing validity duration of the TAT of the candidate cell is included in the candidate cell configuration information. Before determining the target cell for cell switching, the UE does not parse the candidate cell configuration information to obtain the validity duration of the TAT. Now the validity duration of the TAT is placed outside the candidate cell configuration information in the RRC reconfiguration message, so that the UE can obtain the validity duration of the TAT without parsing the candidate cell configuration information in the RRC reconfiguration message after receiving the RRC reconfiguration message.

[0138] Next, the meaning of the validity duration of the TAT is described in detail.

[0139] For any candidate cell, when the duration of the TAT of the candidate cell is indicated to the UE by the serving cell, the validity 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.

[0140] 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.

[0141] 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.

[0142] 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.

[0143] If the network configures the TAT for the candidate cell, the following describes the starting time of the TAT in detail.

[0144] 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.

[0145] For any candidate cell, if the network 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.

[0146] S503, the UE initiates the conditional handover to the first candidate cell based on the TA of the first candidate cell.

[0147] 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. After the random access process is completed, it indicates that the UE successfully switches to the first candidate cell.

[0148] In the above examples, the network device to which the serving cell belongs can obtain the duration of the TAT of the candidate cell 1 in advance in the LTM preparation process, or obtain the duration of the TAT of the candidate cell 1 after the network device to which the candidate cell 1 belongs indicates the TA to the network device to which the serving cell belongs. Figure 5In the illustrated embodiment, before determining the target cell and performing 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.

[0149] For ease of understanding, the following examples are given to illustrate the process of the present application in detail.

[0150] Example 1

[0151] S1, the network device to which the serving cell belongs sends a PDCCH command to the UE to trigger the early synchronization process.

[0152] 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.

[0153] 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.

[0154] S4, the network device to which the serving cell belongs can send the TAs of the three candidate cells to the UE through MAC CE.

[0155] 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.

[0156] 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.

[0157] Example 2,

[0158] S1, the UE receives a preconfigured early synchronization trigger condition of candidate cell 1, candidate cell 2 and candidate cell 3 of the network device to which the serving cell belongs.

[0159] S2, for candidate cell 1, if the UE meets the early synchronization trigger condition of candidate cell 1, the UE can obtain the TA of candidate cell 1 through early synchronization, that is, the UE can receive the RAR sent by the network device to which candidate cell 1 belongs, and the RAR carries the TA of candidate cell 1.

[0160] The UE can obtain the TA of candidate cell 2 and the TA of candidate cell 3 in the same way.

[0161] For S2, the UE can determine that the TA of candidate cell 1 is valid when the TA of candidate cell 1 is received.

[0162] If the network side does not configure the TAT for candidate cell 1, the network device to which candidate cell 1 belongs can send indication information to the UE when it is determined that the TA of candidate cell 1 is invalid, the indication information indicates that the TA of candidate cell 1 is invalid; the UE can re-perform early synchronization based on the indication information to obtain the valid TA of candidate cell 1, or the UE can further determine whether candidate cell 1 meets the early synchronization trigger condition, if it meets the early synchronization trigger condition, the UE can re-perform early synchronization with candidate cell 1 to obtain the valid TA of candidate cell 1.

[0163] Example 3,

[0164] S1, the network device to which the serving cell belongs sends a PDCCH command to the UE to trigger the early synchronization process.

[0165] S2, the UE initiates early synchronization with the network device to which candidate cell 1 belongs to obtain the TA of candidate cell 1; the UE initiates early synchronization with the network device to which candidate cell 2 belongs to obtain the TA of candidate cell 21; the UE initiates early synchronization with the network device to which candidate cell 3 belongs to obtain the TA of candidate cell 3.

[0166] 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.

[0167] 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.

[0168] Example 4,

[0169] S1, the network device to which the serving cell belongs sends a PDCCH command to the UE to trigger the early synchronization process.

[0170] S2, the UE initiates early synchronization to 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.

[0171] 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.

[0172] 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.

[0173] 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.

[0174] 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.

[0175] The TA of the alternative cell is valid within a running period of the TAT of the alternative cell.

[0176] 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 the UE receives indication information sent by the network device to which the serving cell belongs within the running period of the TAT of the alternative cell, the indication information indicating that the TA of the alternative cell is invalid; the UE can re-synchronize in advance to obtain the valid TA of the alternative cell based on the indication information, and optionally, the valid time length of the TAT; or the UE can further determine whether the alternative cell meets the trigger condition of early synchronization, and if the trigger condition of early synchronization is met, the UE can re-synchronize in advance with the alternative cell to obtain the valid TA of the alternative cell, and optionally, the valid time length of the TAT.

[0177] One or more beam information can also be carried in the MAC CE, and the beam information can be identified by the target configuration ID to which the alternative cell belongs.

[0178] Example 5,

[0179] S1, the UE receives the preconfigured early synchronization trigger condition of the alternative cell 1, the alternative cell 2 and the alternative cell 3 of the network device to which the serving cell belongs.

[0180] S2, for the alternative cell 1, if the UE meets the early synchronization trigger condition of the alternative cell 1, the UE can obtain the TA and the valid time length of the TAT of the alternative cell 1 through early synchronization, that is, the UE can receive the RAR sent by the network device to which the alternative cell 1 belongs, and the RAR carries the TA and the valid time length of the TAT of the alternative cell 1.

[0181] The UE can obtain the TA and the valid time length of the TAT of the alternative cell 2 and the TA and the valid time length of the TAT of the alternative cell 3 in the same way.

[0182] For S2, the UE can start the TAT of the alternative cell 1 when receiving the TA of the alternative cell 1.

[0183] Within the running period of the TAT of the alternative cell 1, the TA of the alternative cell 1 is valid.

[0184] When the TAT of the alternative cell 1 expires, the TA of the alternative cell 1 is invalid, or the TA of the alternative cell 1 is invalid when the UE receives the indication information sent by the network device to which the alternative cell belongs within the running period of the TAT of the alternative cell 1, the indication information indicating that the TA of the alternative cell 1 is invalid; the alternative cell 1 can re-obtain the valid TA of the alternative cell 1 through early synchronization when the trigger condition of early synchronization is met, and optionally, the valid time length of the TAT.

[0185] Example 6,

[0186] 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 the 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.

[0187] 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.

[0188] 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.

[0189] 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.

[0190] Figure 6 A structural schematic diagram of a communication apparatus provided by an embodiment of the present application is shown in FIG. 1. As shown in the figure, the apparatus 10 includes: Figure 6

[0191] A receiving module 11, configured to receive the TA of at least one candidate cell;

[0192] A processing module 12, configured to initiate conditional handover to a first candidate cell based on the TA of the first candidate cell in the at least one candidate cell, the first candidate cell being a cell in the at least one candidate cell that meets the trigger condition of the conditional handover.

[0193] ​In a possible implementation, the receiving module 11 is specifically configured to:

[0194] receive the TA of the at least one candidate cell from the serving cell; or

[0195] receive the TA of the at least one candidate cell from the at least one candidate cell respectively.

[0196] In a possible implementation, the receiving module 11 is further configured to:

[0197] receive a TA validity instruction of the first candidate cell sent from the serving cell, the TA validity instruction indicating that the TA of the first candidate cell is valid.

[0198] 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.

[0199] In a possible implementation, the receiving module 11 is further configured to:

[0200] receive the valid duration of the TAT of the first candidate cell.

[0201] 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, and the first delay is a communication duration between the first candidate cell and the serving cell.

[0202] In a possible implementation, the receiving module 11 is further configured to:

[0203] start the TAT of the first candidate cell upon receiving the TA sent by the first candidate cell; or

[0204] start the TAT of the first candidate cell upon receiving the TA validity instruction of the first candidate cell sent by the serving cell.

[0205] In a possible implementation, the first candidate cell is a cell that meets the 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.

[0206] In a possible implementation, the receiving module 11 is further configured to:

[0207] receive indication information, the indication information indicating that the TA of the second candidate cell is invalid.

[0208] In a possible implementation, the TA of the second candidate cell is invalid, including that a TAT of the second candidate cell is overdue.

[0209] In a possible implementation, the apparatus 10 further includes a sending module 13 configured to:

[0210] If the TA of the first candidate cell is invalid and the first candidate cell meets the triggering condition of the handover, initiating random access to the first candidate cell.

[0211] The communication apparatus 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 repeated here.

[0212] Figure 7 Another structural schematic diagram of a communication apparatus is provided for the embodiments of the present application. As shown in the figure, the apparatus 20 includes: Figure 7

[0213] A processing module 21 configured to acquire the TA of at least one candidate cell.

[0214] A sending module 22 configured to send the TA of the at least one candidate cell.

[0215] In a possible implementation, the sending module 22 is specifically configured to:

[0216] send the TA of the at least one candidate cell from the serving cell; or

[0217] send the timing advance TA from the at least one candidate cell respectively.

[0218] In a possible implementation, the sending module 22 is further configured to:

[0219] 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.

[0220] 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 the running time length of the TAT of the first candidate cell.

[0221] In a possible implementation, the sending module 22 is further configured to:

[0222] send the valid time length of the TAT of the first candidate cell.

[0223] 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.

[0224] ​In a possible implementation, the first candidate cell is a cell in the at least one candidate cell other than the second candidate cell, and the second candidate cell fails to meet the triggering condition.

[0225] In a possible implementation, the sending module 22 is further configured to:

[0226] The indication information indicates that the second candidate cell fails to meet the triggering condition, and the second candidate cell is a cell in the at least one candidate cell other than the first candidate cell.

[0227] 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 will not be repeated here.

[0228] Figure 8 Another structure diagram of a communication apparatus provided by the embodiments of the present application is provided. Please refer to Figure 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 transmission port, a transmission interface, or similar descriptions. The receiver can also be referred to as a receiver, a receiver, a receiving port, a receiving interface, or similar descriptions. Exemplarily, the transceiver 31, the memory 32, and the processor 33 are connected to each other through a bus 34.

[0229] The memory 32 is configured to store program instructions.

[0230] The processor 33 is configured to execute the program instructions stored in the memory, so that the communication apparatus 30 performs the steps performed by the UE or the steps performed by the network device in the method embodiments described above.

[0231] The transceiver 31 is configured to perform the transceiving functions of the communication apparatus 30 in the communication method described above.

[0232] The communication apparatus 30 can be a chip, a module, an integrated development environment (IDE), or the like.

[0233] 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 will not be repeated here.

[0234] The embodiments of the present application provide a computer readable storage medium, and the computer readable storage medium stores computer execution instructions. When the computer execution instructions are executed on a computer, any one of the communication methods described above is executed.

[0235] The embodiment of the present application can also provide a computer program product, which can be executed by a processor, and when the computer program product is executed by a computer, the communication method of any of the above is executed.

[0236] All or part of the steps of the above method embodiments can be completed by program instruction related hardware. The foregoing program can be stored in a readable memory. When the program is executed, the steps of the above method embodiments are executed; and the foregoing 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.

[0237] The embodiments of the present application are described with reference to 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 the combination of the 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 generate a device that realizes the functions specified in the flowcharts and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1 an apparatus that performs the functions specified in the flowchart and / or block diagram.

[0238] These computer program instructions can also be stored in a computer readable memory that can guide the computer or other programmable data processing devices to work in a specific way, so that the instructions stored in the computer readable memory produce a product including instruction devices, which realize the functions specified in the flowcharts and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1 an apparatus that performs the functions specified in the flowchart and / or block diagram.

[0239] 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 executed 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 a product for realizing the functions specified in the flowcharts and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1 an apparatus that performs the functions specified in the flowchart and / or block diagram.

[0240] It will be apparent to those skilled in the art that various modifications and variations can be made to the present application without departing from the spirit or scope of the application. Thus, it is intended that the present application cover modifications and variations of this application provided they come within the scope of the appended claims and their equivalents.

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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