Handover method and communication device

Abstract

Disclosed in some embodiments of the present disclosure are a handover method and a communication device. When a target cell for handover is selected from among a plurality of candidate cells, factors such as whether a terminal has a valid TA for a candidate cell and / or whether the candidate cell has configured, for the terminal, a CG that is allowed (or "available") for use are considered.

Description

Switching methods and communication devices

[0001] This disclosure is based on and claims priority to Chinese Patent Application No. 2025100820233.X, filed on January 17, 2025, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates to the field of communication technology, and in particular to a switching method and a communication device. Background Technology

[0003] New Radio (NR) introduces Layer 1 or Layer 2 triggered mobility (LTM). In continuous LTM handover scenarios, a terminal can execute the LTM handover procedure multiple times consecutively. For example, if a terminal executes two consecutive LTM handover procedures, after accessing cell 1, the terminal can handover from cell 1 to cell 2 based on the LTM handover procedure, and then handover from cell 2 to cell 3 based on the LTM handover procedure.

[0004] In order to successfully execute a continuous LTM handover process, network devices can configure multiple candidate cells for the terminal and the handover execution conditions corresponding to each candidate cell. Summary of the Invention

[0005] Some embodiments of this disclosure provide a handover method and communication device that can improve the success rate of handover and reduce service interruption time during the handover process.

[0006] In a first aspect, some embodiments of this disclosure provide a handover method, which can be executed by a terminal or by a device matched with the terminal, such as a processor, chip, or chip module. The method may include: in response to multiple candidate cells meeting the handover execution conditions, determining a target cell for handover from the multiple candidate cells based on whether the terminal has a valid Timing Advance (TA) for the candidate cells, and / or whether the candidate cells have configured a Configured Grant (CG) that allows (or is "available") for the terminal; and accessing the target cell.

[0007] Based on the method described in the first aspect, when selecting a target cell for handover from multiple candidate cells, factors such as whether the terminal has a valid TA in the candidate cell, and / or whether the candidate cell has configured a CG that is allowed to be used (or available) for the terminal are considered. This helps the terminal select a better target cell from multiple candidate cells. For example, a better target cell meets the following conditions: the terminal has a valid TA in the target cell, and the target cell has configured a CG that is allowed to be used (or available) for the terminal. This effectively improves the handover success rate and reduces service interruption time during the handover process.

[0008] In one possible implementation, the target cell for handover is determined from multiple candidate cells based on whether the terminal has a valid TA (Transfer Address) for the candidate cell, and / or whether the candidate cell has configured an available CG (Cell Garbage Collection) for the terminal. This includes: determining whether there exists a cell among the multiple candidate cells that meets a first condition; the cell meeting the first condition is that the terminal has a valid TA for that cell, and that cell has configured an available CG for the terminal; in response to the existence of a cell meeting the first condition, the cell meeting the first condition is selected as the target cell for handover. Therefore, in this implementation, the terminal can select a cell meeting the first condition from multiple candidate cells that meet the handover execution conditions as the target cell for handover. Having a valid TA for a cell meeting the first condition, and the cell meeting the first condition configuring an available CG for the terminal, allows the terminal to directly access the cell using the valid TA and the configured available CG, without needing to monitor the cell's downlink control information (DCI) or perform random access, thus improving the handover success rate and reducing service interruption time during the handover process.

[0009] In one possible implementation, given that the number of cells satisfying the first condition is N, the target cell for handover is the cell among the N cells satisfying the first condition that has the largest number of beams with a signal quality value greater than or equal to a first threshold, where N is an integer greater than 1. Therefore, in this implementation, the terminal considers the number of beams with a signal quality value greater than or equal to the first threshold when selecting the target cell, which is beneficial for the terminal to access the target cell with better signal quality, thereby further improving the handover success rate and reducing service interruption time during the handover process.

[0010] In one possible implementation, after determining whether a cell satisfying a first condition exists among multiple candidate cells, the method further includes: in response to the absence of a cell satisfying the first condition, selecting a cell satisfying a second condition from among the multiple candidate cells as the target cell for handover; the cell satisfying the second condition includes at least one of the following: the terminal has a valid TA in the cell; the cell is configured with an available CG for the terminal; or, the cell has the largest number of beams with signal quality values ​​greater than or equal to a first threshold. Therefore, in this implementation, when no cell satisfies the first condition, the terminal can subsequently select a cell satisfying the second condition as the target cell for handover. The selection of the target cell considers factors such as whether the terminal has a valid TA in the candidate cell, whether the candidate cell is configured with an available CG for the terminal, or the number of beams with signal quality values ​​greater than or equal to the first threshold, which helps improve the success rate of handover and reduce service interruption time during handover.

[0011] In one possible implementation, after determining whether there is a cell among multiple candidate cells that meets the first condition, the method further includes: in response to the absence of a cell meeting the first condition, selecting any cell from the multiple candidate cells that meets the handover execution conditions as the target cell for handover. This implementation is thus simpler and more convenient.

[0012] In one possible implementation, the method further includes: continuing to save the transfer dates (TAs) of multiple candidate cells before the terminal performs a handover and successfully accesses the target cell. As can be seen, in this implementation, the terminal can continue to save the TAs of multiple candidate cells. This is beneficial for the terminal to subsequently use the saved TAs for access, eliminating the need to obtain the TAs of candidate cells again, and reducing signaling interactions.

[0013] In one possible implementation, the candidate cells for continuing to save the TA include at least one of the following: candidate cells where the TA is a valid TA; candidate cells belonging to the same network device as the target cell for handover; or candidate cells indicated by the indication information that the TA needs to be saved. Therefore, in this implementation, the terminal can selectively save the TAs of some candidate cells without needing to save the TAs of all candidate cells, effectively saving storage resources.

[0014] In one possible implementation, the target cell for handover is determined from multiple candidate cells based on whether the terminal has a valid TA for the candidate cell and / or whether the candidate cell has a CG that is allowed to be used (or available) for the terminal. This includes: selecting a cell that meets a third condition from the multiple candidate cells as the target cell for handover; the cell that meets the third condition includes at least one of the following: the terminal has a valid TA for the cell; or the cell has a CG that is allowed to be used (or available) for the terminal. Therefore, in this implementation, the terminal considers factors such as whether it has a valid TA for the candidate cell or whether the candidate cell has a CG that is allowed to be used (or available) for the terminal when selecting the target cell, which helps to improve the success rate of handover and reduce service interruption time during the handover process.

[0015] Secondly, some embodiments of this disclosure provide a communication device that includes units or modules for performing the methods described in the first aspect or alternative implementations thereof.

[0016] Thirdly, some embodiments of this disclosure provide a communication device, including a processor, a memory, and a computer program or instructions stored in the memory, wherein the processor executes the computer program or instructions to cause the communication device to implement the steps of the method involved in the first aspect or its optional implementations described above.

[0017] Fourthly, some embodiments of this disclosure provide a chip including at least one processor, wherein the processor is configured to execute program instructions to perform the steps of the methods involved in the first aspect or alternative implementations thereof.

[0018] Fifthly, some embodiments of this disclosure provide a chip module, including a communication interface and a chip. The communication interface is used for internal communication within the chip module or for communication between the chip module and an external device. The chip is used to perform the steps of the methods involved in the first aspect or its optional implementations described above.

[0019] Sixthly, some embodiments of this disclosure provide a computer-readable storage medium storing a computer program or instructions that, when executed, implement the steps of the method involved in the first aspect or its optional implementations described above.

[0020] In a seventh aspect, some embodiments of this disclosure provide a computer program product, including a computer program or instructions, wherein when the computer program or instructions are executed, they implement the steps of the method involved in the first aspect or its optional implementations described above. Attached Figure Description

[0021] Figure 1 is a schematic diagram of a communication system;

[0022] Figure 2 is a schematic diagram of a beam deployment scenario;

[0023] Figure 3 is a schematic diagram of an LTM switching process;

[0024] Figure 4 is a flowchart illustrating a switching method provided by some embodiments of this disclosure;

[0025] Figure 5 is a flowchart illustrating another switching method provided by some embodiments of this disclosure;

[0026] Figure 6 is a flowchart illustrating another switching method provided by some embodiments of this disclosure;

[0027] Figure 7 is a schematic diagram of the structure of a communication device provided in some embodiments of this disclosure;

[0028] Figure 8 is a schematic diagram of the structure of another communication device provided in some embodiments of this disclosure;

[0029] Figure 9 is a schematic diagram of the structure of a chip module provided in some embodiments of this disclosure. Detailed Implementation

[0030] In this disclosure, the terms "first," "second," etc., are used to distinguish identical or similar items with essentially the same function and purpose. Those skilled in the art will understand that the terms "first," "second," etc., do not limit the quantity or execution order, nor do they imply that they must be different. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0031] It should be understood that in this disclosure, "at least one" refers to one or more; "multiple" refers to two or more. Furthermore, the word "equal to" in this disclosure can be used with either "greater than" or "less than". When "equal to" and "greater than" are used together, the technical solution using "greater than" is adopted; when "equal to" and "less than" are used together, the technical solution using "less than" is adopted.

[0032] Some embodiments of this disclosure can be applied to fourth-generation (4G) systems; or to fifth-generation (5G) systems, also known as new radio (NR) systems; or to sixth-generation (6G) systems, or seventh-generation (7G) systems, or other future communication systems; or they can also be used in device-to-device (D2D) systems, machine-to-machine (M2M) systems, vehicle-to-everything (V2X) systems, etc. Some embodiments of this disclosure can be applied to other network architectures, including but not limited to terrestrial communication network architectures, non-terrestrial communication network architectures, relay network architectures, dual-link architectures, and vehicle-to-everything communication architectures.

[0033] For example, FIG1 is a schematic diagram of a communication system according to some embodiments of the present disclosure. As shown in FIG1, the communication system 100 includes one network device 101 and two terminal devices 102 as an example for illustration. The network device 101 and the terminal devices 102 can communicate with each other. For example, the terminal devices 102 can send signaling and / or data to the network device 101 through the uplink, and the network device 101 can send signaling and / or data to the terminal devices 102 through the downlink. The communication system 100 may include multiple network devices, and the coverage area of ​​each network device may include other numbers of terminal devices. Some embodiments of the present disclosure do not limit this.

[0034] The terminal involved in some embodiments of this disclosure is a device with wireless transceiver capabilities, and may also be referred to as terminal equipment, user equipment (UE), mobile station (MS), mobile terminal (MT), access terminal, Internet of Things terminal, vehicle-mounted terminal, industrial control terminal, UE unit, UE station, mobile station, remote station, remote terminal, mobile device, wireless communication device, UE agent, or UE device, etc. The terminal can be fixed or mobile. It should be noted that the terminal can support at least one wireless communication technology, such as Wideband Code Division Multiple Access (WCDMA), Long Time Evolution (LTE), New Radio (NR), 6th-generation (6G), or next-generation wireless communication technology, etc. For example, a terminal can be a mobile phone, tablet, desktop computer, laptop computer, all-in-one computer, in-vehicle terminal, virtual reality (VR) terminal, augmented reality (AR) terminal, mixed reality (MR) terminal, wireless terminal in industrial control, wireless terminal in self-driving, wireless terminal in remote medical surgery, wireless terminal in smart grid, wireless terminal in transportation safety, wireless terminal in smart city, wireless terminal in smart home, cellular phone, cordless phone, session initiation protocol (SIP) phone, wireless local loop (WLL) station, personal digital assistant (PDA), handheld device with wireless communication capabilities, computing device or other processing device connected to a wireless modem, wearable device, terminal in future mobile communication networks, or terminal in future evolved public land mobile network (PLMN), etc. In some embodiments of this disclosure, the terminal may also be a device with transceiver functions, such as a chip module. The chip module may include a chip, and may also include other discrete components.The embodiments disclosed herein do not limit the specific technology or device form used in the terminal.

[0035] Some embodiments of this disclosure involve network devices that are nodes in a radio access network (RAN), also known as RAN nodes. Network devices are used to help terminal devices achieve wireless access. In one possible scenario, the network device can be a base station, an evolved NodeB (eNodeB), a transmitting and receiving point (TRP), a transmitting point (TP), a next-generation NodeB (gNB), a next-generation base station in a 6G system, a base station in a future mobile communication system, a satellite, an integrated access and backhaul (IAB) node, or a network device in a mobile switching center non-terrestrial network (NTN) communication system; that is, it can be deployed on a high-altitude platform or satellite, etc. The network device can be a macro base station, a micro base station or an indoor station, a relay node or a host node, or a wireless controller in a cloud radio access network (CRAN) scenario. Network devices can also function as base stations in device-to-device (D2D) communication, vehicle-to-everything (V2X) communication, drone communication, and machine-to-machine (M2M) communication. Optionally, network devices can also be servers, wearable devices, vehicles, or in-vehicle equipment. For example, in vehicle-to-everything (V2X) technology, the network device can be a roadside unit (RSU).

[0036] All or part of the functions of the network device in this disclosure can also be implemented through software functions running on hardware, or through virtualization functions instantiated on a platform (e.g., a cloud platform). The network device in this disclosure can also be a logical node, logical module, or software capable of implementing all or part of the functions of a network device.

[0037] In another possible scenario, multiple network devices collaborate to assist terminal devices in achieving wireless access, with each network device performing a portion of the base station's functions. For example, network devices can be central units (CUs), distributed units (DUs), CU-control plane (CPs), CU-user plane (UPs), or radio units (RUs). CUs and DUs can be separate entities or included in the same network element, such as a baseband unit (BBU). RUs can be included in radio equipment or radio units, such as remote radio units (RRUs), active antenna units (AAUs), or remote radio heads (RRHs). It is understood that network devices can be CU nodes, DU nodes, or devices comprising both CU and DU nodes. Furthermore, CUs can be classified as network devices in the access network (RAN) or the core network (CN), without limitation.

[0038] It is understood that the system architecture described in some embodiments of this disclosure is for the purpose of more clearly illustrating the technical solutions of some embodiments of this disclosure, and does not constitute a limitation on the technical solutions provided by some embodiments of this disclosure. Those skilled in the art will know that as system architecture evolves and new business scenarios emerge, the technical solutions provided by some embodiments of this disclosure are also applicable to similar technical problems.

[0039] The following describes some of the relevant concepts involved in the embodiments of this disclosure.

[0040] 1. Timing Advance (TA)

[0041] TA, used for terminal uplink transmission, refers to the time advance by which the terminal sends uplink subframes compared to receiving downlink subframes. In other words, TA is the terminal's timing advance for a specific cell. Different terminals can have different or the same TA, depending on the relative position between the terminal and the network equipment. Different terminals can use their own TAs to send uplink data, ensuring that uplink data from different terminals arrives at the network side at the same time, thus facilitating correct reception of uplink data by the network side. Optionally, TA can be calculated by the network side based on the preamble sent by the terminal.

[0042] 2. Configure Grant (CG)

[0043] A CG is a pre-configured transmission resource used by a terminal when performing uplink transmissions. In other words, a terminal can use the transmission resources of a CG to transmit uplink data. Optionally, during the LTM handover process, the terminal can access the network side through a CG that is configured by the network side to be allowed to use (or "available"), and complete the Radio Resource Control Reconfiguration (RRC Reconfiguration) through the transmission resources corresponding to the CG.

[0044] 3. Residential area

[0045] In a cellular mobile communication system, a cell is an area covered by a network device or a portion thereof (such as a sector antenna). Within this area, terminals can communicate with the network device via wireless channels. A cell is the basic unit of a mobile communication network, used to cover signals and provide wireless signal services.

[0046] 4. Configuration Information

[0047] Configuration information refers to the configuration information configured for the terminal by the serving cell or candidate cell. For configuration parameters configured for the terminal by the candidate cell, the configuration information may include the configuration parameters of the candidate cell and / or the configuration parameters of subsequent candidate cells. Optionally, the configuration parameters may include, but are not limited to, at least one of the following: cell identifier, terminal configuration in the cell, or terminal resource configuration information (such as CG) in the cell.

[0048] The serving cell can also be replaced with "source cell", "currently accessed cell", or "currently serving cell". The serving cell is the cell under the jurisdiction of the source network device (such as a base station or CU).

[0049] Candidate cells can also be replaced with "neighboring cells", "neighboring cells of the terminal's current serving cell", "candidate handover target cell", or "handover target cell". Candidate cells are cells under the jurisdiction of candidate network devices (such as base stations or CUs).

[0050] Subsequent candidate cells of a candidate cell refer to candidate cells associated with the serving cell when the candidate cell is used for access. For example, if a communication system deploys cells 1, 2, and 3, and the candidate cell and its subsequent candidate cell are located among cells 1, 2, and 3, then cells 2 and 3 are subsequent candidate cells of cell 1, cells 1 and 3 are subsequent candidate cells of cell 2, and cells 1 and 2 are subsequent candidate cells of cell 3. In response to a terminal accessing cell 1, cells 2 and 3 become candidate cells; in response to a terminal accessing cell 2, cells 1 and 3 become candidate cells; and in response to a terminal accessing cell 3, cells 1 and 2 become candidate cells.

[0051] Optionally, in a continuous LTM handover process, the network side needs to pre-configure one or more neighboring cells of a certain cell as LTM candidate cells and send the configuration information of the candidate cells to the terminal in advance.

[0052] In one implementation, a candidate cell can send its configuration information to the serving cell, which then forwards this information to the terminal. In this way, the candidate cell can successfully configure the terminal. Optionally, this configuration information can be transmitted transparently; for example, it can be carried within a transparent container (Target NG-RAN node To Source NG-RAN node Transparent Container) for transmission. With transparent transmission, the serving cell does not need to parse the configuration information, effectively preventing data leakage and enhancing security.

[0053] 5. Beam

[0054] An NR cell typically consists of multiple beams, and the network achieves complete coverage within a region through beam sweeping. A cell can consist of up to 64 beams.

[0055] The signal quality value of a beam can be determined by the signal quality value of the corresponding reference signal. Taking a Synchronization Signal Block (SSB) as an example, in response to the correspondence between SSB1 and beam 1, if the terminal detects that the signal quality value of SSB1 sent by the network side is greater than or equal to a first threshold, then the signal quality value of beam 1 is also greater than or equal to the first threshold, and the beam 1 corresponding to SSB1 is an allowed (or available) beam. As an example, the reference signal can be a Synchronization Signal Block (SSB), that is, different beams are identified through different SSBs, and there is a correspondence between SSBs and beams; in other examples, the reference signal can also be a non-zero-power Channel State Information (CSI-RS), that is, different beams are identified through different CSI-RSs, and there is a correspondence between CSI-RSs and beams.

[0056] There can be a correspondence between beams and CGs, which can be a one-to-one mapping or a many-to-one mapping. The specific mapping relationship can be configured based on requirements. For example, a cell includes beam 1 and beam 2, and the configured CGs include CG1 and CG2. Beam 1 corresponds to CG1, and beam 2 corresponds to CG2.

[0057] 6. Beam-related CG configuration scheme

[0058] The CG configuration scheme disclosed herein allows for the configuration of CGs for some beams of a candidate cell, without requiring CGs to be configured for all beams. In one implementation, the configured CG is related to the path taken by the terminal to enter the candidate cell. The CG configuration scheme for the candidate cell may differ depending on the path taken by the terminal to enter the candidate cell.

[0059] For example, Figure 2 illustrates a scenario diagram of beam deployment. Assume the terminal's current serving cell is cell 1, and candidate cells are cell 2 and cell 3. Cell 1 consists of beams 1 and 2, cell 2 consists of beams 3 and 4, and cell 3 consists of beams 5 and 6. Specifically, beam 1 is the beam accessed when the terminal switches from cell 2 to cell 1, and beam 2 is the beam accessed when the terminal switches from cell 3 to cell 1. The CG for beam 1 and the CG for beam 2 can be different. Similarly, beam 3 is the beam accessed when the terminal switches from cell 1 to cell 2, and beam 4 is the beam accessed when the terminal switches from cell 3 to cell 2. The CG for beam 3 and the CG for beam 4 can be different. Finally, beam 5 is the beam accessed when the terminal switches from cell 1 to cell 3, and beam 6 is the beam accessed when the terminal switches from cell 2 to cell 3. The CG for beam 5 and the CG for beam 6 can be different.

[0060] As shown in Figure 2(a), in response to the terminal entering cell 3 via the path of cell 1→cell 2→cell 3, CG can be configured for beam 3 of cell 2 and beam 6 of cell 3, while beam 4 of cell 2 and beam 5 of cell 3 do not need to be configured with CG; as shown in Figure 2(b), in response to the terminal entering cell 3 via the path of cell 1→cell 3, CG can be configured for beam 6 of cell 3, while beam 5 of cell 3 and beams 3 and 4 of cell 2 do not need to be configured with CG.

[0061] The CG configuration scheme disclosed herein is applicable to various switching scenarios, such as RACH-less switching, and is not limited thereto.

[0062] As can be seen, when deploying CGs corresponding to beams, CGs can be configured for some beams of candidate cells based on the terminal's path. That is, CGs can be configured selectively based on the terminal's path, which can significantly reduce the number of CGs and effectively save resources.

[0063] 7. LTM Switchover Process

[0064] LTM handover process refers to the handover process that changes the serving cell of a terminal based on Layer 1 or Layer 2 (L1 or L2) signaling.

[0065] Figure 3 is a schematic diagram of an LTM handover process. The possible steps of this LTM handover process are as follows:

[0066] 201. The source cell sends measurement configuration to the terminal.

[0067] Accordingly, the terminal receives the measurement configuration.

[0068] A Radio Resource Control (RRC) connection and a data radio bearer are established between the terminal and the source cell in order to perform communication services.

[0069] Measurement configuration is used to configure measurement events, such as measurement event A3 and / or measurement event A5. Measurement event A3 is when the signal quality of a neighboring cell is better than the signal quality of the serving cell by a certain threshold, such as an offset value. Measurement event A5 is when the signal quality of a neighboring cell is better than a threshold (such as threshold value 1), while the signal quality of the serving cell is worse than another threshold (such as threshold value 2).

[0070] After receiving the measurement configuration, the terminal can measure neighboring cells and / or serving cells and generate corresponding measurement reports.

[0071] 202. The terminal reports the measurement report to the source cell.

[0072] Measurement reports may be event-triggered or periodically reported by the terminal.

[0073] 203. The source cell decision terminal needs to perform a handover.

[0074] For example, the source cell determines that the terminal needs to perform a handover based on at least one of the following: measurement reports, radio resource management (RRM) related measurement reports, or the load status of each cell.

[0075] 204. The source cell sends a handover request message to the candidate cell. The handover request message is used to request that the terminal be handed over to the candidate cell.

[0076] The candidate cells can be selected based on at least one of the following: measurement reports, RRM-related measurement reports, or the load conditions of each cell.

[0077] 205. The candidate cell returns a handover request confirmation message, which is used to inform the source cell / candidate cell that it agrees to hand over the terminal to the candidate cell.

[0078] Optionally, the handover request confirmation message can also be used to inform the source cell / candidate cell that it does not agree to hand over the terminal to the candidate cell. The handover request confirmation message may also include the terminal's radio parameter configuration in the candidate cell, which may include resource configuration information for random access.

[0079] 206. The source cell sends a Radio Resource Control Reconfiguration (RRC Reconfiguration) message to the terminal.

[0080] Optionally, the RRC Reconfiguration message includes the identifier of the candidate cell for handover, the terminal's configuration in the candidate cell, and / or the resource configuration information for the terminal to perform random access in the candidate cell.

[0081] 207. The terminal sends a Radio Resource Control Reconfiguration Complete (RRC Reconfiguration Complete) message to the source cell.

[0082] 208. Perform advance synchronization between the terminal and the candidate cell.

[0083] Optionally, the terminal performs uplink and / or downlink synchronization in the candidate cell.

[0084] Step 208 is an optional step.

[0085] 209. The terminal reports a Layer 1 or Layer 2 measurement report to the source cell.

[0086] 210. The source cell sends an LTM Cell Switch Command to the terminal, instructing the terminal to perform a cell switch.

[0087] Optionally, the handover command may be carried by a Media Access Layer Control Element (MAC CE), which is carried by a Physical Downlink Shared Channel (PDSCH).

[0088] 211. The terminal accesses the target cell, optionally performing random access; the terminal sends an RRC Reconfiguration Complete message to the target cell (e.g., candidate cell 1).

[0089] As can be seen, in the LTM handover process described in Figure 3, after the terminal performs uplink and / or downlink synchronization in the candidate cell, it can report an L1 measurement report or an L2 measurement report. Then, the network side can instruct the terminal to perform cell handover based on the L1 measurement report or the L2 measurement report.

[0090] In one implementation, step 208 may specifically include, but is not limited to, the following steps:

[0091] 208-1. The source cell sends a TA request to the candidate cell.

[0092] Accordingly, the candidate cell receives the TA request.

[0093] 208-2. Candidate cells assign preamble codes to terminals.

[0094] After a candidate cell receives a TA request, it can respond to the TA request and allocate a preamble.

[0095] 208-3. The candidate cell sends a TA response to the source cell.

[0096] Accordingly, the source cell can receive the TA response.

[0097] The TA response may include the preamble assigned to the terminal by the candidate cell.

[0098] 208-4. The source cell sends the preamble to the terminal.

[0099] Accordingly, the terminal can receive the preamble.

[0100] Optionally, the source cell can send the preamble via Downlink Control Information (DCI), or in other words, the preamble identifier can be carried by the DCI.

[0101] Optionally, the DCI can be carried by the Physical Downlink Control Channel (PDCCH).

[0102] 208-5. The terminal sends the preamble to the candidate cell.

[0103] Accordingly, the candidate cell receives the preamble.

[0104] 208-6. In response to the accurate reception of the preamble, the candidate cell determines the TA corresponding to the terminal based on the preamble.

[0105] 208-7. The candidate cell sends the TA corresponding to the terminal to the source cell.

[0106] Accordingly, the source cell receives the TA.

[0107] 208-8. The source cell sends the TA corresponding to the candidate cell to the terminal.

[0108] Accordingly, the terminal receives the TA.

[0109] Optionally, the TA can be carried by the MAC CE. The same MAC CE can indicate the TA corresponding to one or more candidate cells, that is, the MAC CE needs to indicate the correspondence between candidate cells and TAs.

[0110] 208-9. Based on this TA, uplink synchronization is achieved between the terminal and the candidate cell.

[0111] As can be seen, in step 208, the terminal obtains the TA of the candidate cell, and the terminal does not need to continuously monitor the random access response of the candidate cell, which can effectively avoid data transmission interruption.

[0112] In one implementation, the network side can also pre-configure multiple candidate cells and corresponding handover execution conditions (or triggering conditions) for the terminal. After receiving the configuration information, the terminal can evaluate the candidate cells and actively hand over to the target cell if the candidate cells meet the handover execution conditions. In this implementation, steps 208 to 211 can be replaced by steps 212 to 213:

[0113] 212. Switching execution conditions for terminal evaluation condition switching.

[0114] Optionally, the terminal evaluates the handover execution conditions of multiple candidate cells and determines the target cell for access from the candidate cells that meet the handover execution conditions.

[0115] Optionally, the handover execution conditions for multiple candidate cells and their corresponding conditional handovers can be carried by the RRC Reconfiguration message in step 206, without limitation.

[0116] 213. The terminal accesses the target cell, optionally performing random access; the terminal sends an RRC Reconfiguration Complete message to the target cell (e.g., candidate cell 1).

[0117] To improve communication quality, a continuous LTM handover process can be introduced, which includes multiple consecutive LTM handover procedures. Taking two consecutive LTM handover procedures as an example, after the terminal accesses cell 1, in response to the candidate cell 2 meeting the handover execution conditions, the terminal can handover from cell 1 to cell 2; after the terminal accesses cell 2, in response to the terminal receiving a handover command from cell 2 instructing the terminal to handover to cell 3, the terminal can handover from cell 2 to cell 3.

[0118] In order to successfully execute a continuous LTM handover process, network devices can configure multiple candidate cells for the terminal and the handover execution conditions corresponding to each candidate cell.

[0119] Some embodiments of this disclosure provide a handover method and communication apparatus. In this method, in response to multiple candidate cells meeting the handover execution conditions, the terminal, after determining the target cell, considers factors such as whether the terminal has a valid TA in the candidate cell, and / or whether the candidate cell has configured a CG that is allowed to be used (or available) for the terminal, to determine the target cell for handover from multiple candidate cells, and accesses the target cell. This can effectively improve the success rate of handover and reduce the service interruption time during the handover process.

[0120] Figure 4 is a flowchart illustrating a switching method provided by some embodiments of this disclosure. This switching method can be executed by a terminal. As shown in Figure 4, the switching method may include, but is not limited to, the following steps:

[0121] 301. In response to multiple candidate cells meeting the handover execution conditions, the terminal determines the target cell for handover from among the multiple candidate cells based on whether the terminal has a valid TA in the candidate cell, and / or whether the candidate cell has a usable CG configured for the terminal. This helps the terminal select a better target cell from multiple candidate cells. For example, a better target cell meets the following conditions: the terminal has a valid TA in the target cell, and the target cell has a usable (or "available") CG configured for the terminal. This effectively improves the handover success rate and reduces service interruption time during the handover process.

[0122] Multiple candidate cells satisfying the handover execution conditions includes multiple candidate cells each satisfying their respective handover execution conditions. For example, taking multiple candidate cells including candidate cell 1, candidate cell 2, and candidate cell 3 as an example, multiple candidate cells satisfying the handover execution conditions means that candidate cell 1 satisfies its corresponding handover execution condition, candidate cell 2 satisfies its corresponding handover execution condition, and candidate cell 3 satisfies its corresponding handover execution condition.

[0123] In one implementation, the terminal determines the target cell for handover from multiple candidate cells based on whether the terminal has a valid TA of the candidate cell, and / or whether the candidate cell has a CG that is allowed to be used (or available) for the terminal. This includes any one of the following: the terminal determines the target cell for handover from multiple candidate cells based on whether the terminal has a valid TA of the candidate cell; the terminal determines the target cell for handover from multiple candidate cells based on whether the candidate cell has a CG that is allowed to be used (or available) for the terminal; the terminal determines the target cell for handover from multiple candidate cells based on whether the terminal has a valid TA of the candidate cell and whether the candidate cell has a CG that is allowed to be used (or available) for the terminal.

[0124] Optionally, after executing step 301, the terminal may further execute the step of: selecting a cell that meets a first condition from multiple candidate cells as the target cell for handover; the cell that meets the first condition is that the terminal has a valid TA for that cell, and that cell is configured with a CG that is allowed to be used (or available) for the terminal. For example, for a scenario where step 301 includes: the terminal determines the target cell for handover from multiple candidate cells based on whether the terminal has a valid TA for a candidate cell and whether the candidate cell is configured with a CG that is allowed to be used (or available) for the terminal, in response to the existence of a cell that meets the first condition among multiple candidate cells (the terminal has a valid TA for that cell, and that cell is configured with a CG that is allowed to be used (or available) for the terminal), the terminal selects the cell that meets the first condition as the target cell for handover.

[0125] Optionally, after the terminal performs step 301, it may also perform the following steps: select a cell that meets the third condition from multiple candidate cells as the target cell for handover; the cell that meets the third condition includes at least one of the following cells: the terminal has a valid timing advance for the cell; or, the cell has been configured with a configuration authorization that allows the terminal to use (or is "available"). For example, step 301 includes: in a scenario where the terminal has a valid TA for a candidate cell, and in response to the existence of a cell among multiple candidate cells that meets a third condition (the terminal has a valid TA for that cell), the terminal selects the cell that meets the third condition as the target cell for handover; in another scenario where step 301 includes: in a scenario where the terminal has configured a CG that is allowed to be used (or available) for the terminal in a candidate cell, and in response to the existence of a cell among multiple candidate cells that meets the third condition (that cell has configured a CG that is allowed to be used (or available) for the terminal), the terminal selects the cell that meets the third condition as the target cell for handover; in yet another scenario where step 301 includes: in a scenario where the terminal determines the target cell for handover from multiple candidate cells based on whether the terminal has a valid TA for a candidate cell and whether the candidate cell has configured a CG that is allowed to be used (or available) for the terminal, and in response to the existence of a cell among multiple candidate cells that meets the third condition (the terminal has a valid TA for that cell, or that cell has configured a CG that is allowed to be used (or available) for the terminal), the terminal selects the cell that meets the third condition as the target cell for handover. This implementation method helps improve the success rate of handover and reduce the service interruption time during the handover process.

[0126] In other implementations, if no cell meets the first condition or the third condition among multiple candidate cells, the terminal can select any cell that meets the handover execution conditions from among the multiple candidate cells as the target cell for handover.

[0127] In one optional implementation, a terminal having a valid TA (Target Acquisition) for a candidate cell means that the candidate cell has indicated the terminal's TA in the candidate cell to the terminal through the serving cell, and that TA is a valid TA. In one example, in response to the candidate cell not indicating a TA to the terminal through the serving cell, the terminal does not have a valid TA for the candidate cell; in another example, in response to the candidate cell indicating a TA to the terminal through the serving cell, and the validity period of that TA does not include the current time (i.e., the TA is invalid at this time), the terminal does not have a valid TA for the candidate cell; in yet another example, in response to the candidate cell indicating a TA to the terminal through the serving cell, and the validity period of that TA includes the current time (i.e., the TA is valid at this time, such as before a timer expires), the terminal has a valid TA for the candidate cell.

[0128] In another optional implementation, a terminal having a valid TA in a candidate cell means that the terminal's TA in the candidate cell is calculated based on the terminal's TA in the serving cell, and that TA is a valid TA. In one example, if the terminal's TA in the candidate cell is not calculated from the terminal's TA in the serving cell, the terminal does not have a valid TA in the candidate cell. In another example, if the terminal's TA in the candidate cell is calculated from the terminal's TA in the serving cell, and the valid time range of that TA does not include the current time (i.e., the TA is invalid at this time), the terminal does not have a valid TA in the candidate cell. In yet another example, if the terminal's TA in the candidate cell is calculated from the terminal's TA in the serving cell, and the valid time range of that TA includes the current time (i.e., the TA is valid at this time, such as before a timer expires), the terminal has a valid TA in the candidate cell. Optionally, calculating the terminal's TA in the candidate cell from the terminal's TA in the serving cell includes: the terminal measuring and obtaining the synchronization signal of the candidate cell; and calculating the terminal's TA in the candidate cell based on the terminal's TA in the serving cell and the deviation between the synchronization signal and the synchronization signal of the serving cell.

[0129] If a candidate cell configures a CG that is allowed (or available) for the terminal, it can be understood that the candidate cell has configured a CG for the terminal and that the CG is allowed (or available). In one example, in response to a candidate cell not configuring a CG for the terminal, the candidate cell does not configure a CG that is allowed (or available); in another example, in response to a candidate cell configuring a CG for the terminal, and that CG is disabled (or unavailable), the candidate cell does not configure a CG that is allowed (or available); in yet another example, in response to a candidate cell configuring a CG for the terminal, and that CG is allowed (or available), the candidate cell configures a CG that is allowed (or available).

[0130] In one alternative implementation, the terminal may default to a candidate cell whose CG is a allowed (or available) CG.

[0131] In another optional implementation, the terminal may default to the candidate cell configuring the CG as a prohibited (or unavailable) CG. When the terminal receives an instruction to enable the CG, the terminal may determine the allowed (or available) CG based on the instruction.

[0132] In another alternative implementation, in response to the signal quality value of the beam associated with the CG configured for the terminal by the candidate cell being less than or equal to a second threshold, the terminal may determine that the CG is a prohibited (or unavailable) CG; in response to the signal quality value of the beam associated with the CG configured for the terminal by the candidate cell being greater than the second threshold, the terminal may determine that the CG is a permitted (or available) CG.

[0133] In some embodiments of this disclosure, the permitted CG can be replaced with at least one of the following expressions: "CG agreed to be used", "available CG", "valid CG", or "supported CG". Correspondingly, the above expression "prohibited CG" can also be replaced with at least one of the following expressions: "refused to be used", "unavailable CG", or "unsupported CG".

[0134] 302. Terminal access to target cell.

[0135] In one implementation, in response to the terminal having a valid TA of the target cell and the target cell configuring a CG that is allowed to be used (or "available") for the terminal, the terminal can access the target cell using the valid TA of the target cell and the CG that is allowed to be used (or "available") for the terminal configured by the target cell.

[0136] In another implementation, in response to the terminal having a valid TA of the target cell and the target cell not being configured with a CG that is allowed (or "available") for the terminal, the terminal can respond to the LTM cell handover command on the network side, monitor the downlink control information (DCI) of the target cell, and perform random access.

[0137] In another implementation, in response to the target cell not having a valid TA (Target Translation Transaction) and the target cell configuring an available CG (Cellular Transaction Class) for the terminal, the terminal can calculate the valid TA of the target cell based on the serving cell's valid TA and the TA offset value. The terminal then uses the valid TA of the target cell and the available CG configured for the terminal to access the target cell. The TA offset value is the TA difference between the serving cell's valid TA and the target cell's valid TA, and this TA offset value can be obtained by measurement by the terminal.

[0138] In another implementation, in response to the target cell not having a valid TA and the target cell not having configured a CG that is allowed to be used (or "available") for the terminal, the terminal can respond to the LTM cell handover command on the network side, monitor the DCI of the target cell, and perform random access.

[0139] Optionally, before the terminal performs a handover and successfully accesses the target cell (T304 has been initiated but has not timed out), the terminal can continue to save the TAs of multiple candidate cells. In one implementation, in response to the terminal's failure to access the target cell, the terminal can perform cell selection and choose a suitable cell. If the selected cell is one of the aforementioned candidate cells, the terminal can use the saved TAs and corresponding CGs (if available) of the candidate cells to access the cell and complete the handover. Optionally, in response to the terminal's failure to access the cell again, RRC can be performed to rebuild or release the current connection. Therefore, in this implementation, the terminal can use the saved TAs of the candidate cells to access the cell without needing to obtain the TAs of the candidate cells again, thus reducing signaling interaction.

[0140] The candidate cells for continued retention of time advance include at least one of the following (1) to (3): (1) the time advance is a valid time advance candidate cell; (2) the candidate cell belongs to the same network device as the target cell for handover; (3) the candidate cell for which time advance needs to be retained as indicated by the indication information.

[0141] (1) If the TA of the candidate cell is a valid TA, the terminal continues to save the TA of the candidate cell; if the TA of the candidate cell is an invalid TA, the terminal deletes the invalid TA.

[0142] (2) If the candidate cell and the target cell belong to the same network device (or base station), the terminal continues to save the TA of the candidate cell; if the candidate cell and the target cell belong to different network devices (or base stations), the terminal deletes the TA of the candidate cell. In other implementations, the candidate cell and the target cell belong to the same network device, which can also be understood as the antennas of the candidate cell and the target cell sharing the same site.

[0143] (3) In response to receiving an instruction to continue saving the TA of the candidate cell, the terminal continues to save the TA of the candidate cell; in response to not receiving an instruction to continue saving the TA of the candidate cell, the terminal deletes the TA of the candidate cell. For example, in a scenario where the terminal is considering whether to continue saving the TA of candidate cell 2 and the TA of candidate cell 3, in response to receiving an instruction to continue retaining the TA of candidate cell 2, the terminal may continue to retain the TA of candidate cell 2 and delete the TA of candidate cell 3.

[0144] In other implementations, this approach can also be replaced by: in response to the terminal receiving an instruction to delete the TA of a candidate cell, the terminal deletes the TA of the candidate cell; in response to the terminal not receiving an instruction to delete the TA of a candidate cell, the terminal continues to store the TA of the candidate cell. For example, in a scenario where the terminal is considering whether to continue storing the TA of candidate cell 2 and the TA of candidate cell 3, in response to the terminal receiving an instruction to delete the TA of candidate cell 3, the terminal can delete the TA of candidate cell 3 and continue to store the TA of candidate cell 2.

[0145] As can be seen, the terminal can selectively save the TA of some candidate cells, without having to save the TA of all candidate cells, which can effectively save storage resources.

[0146] In one implementation, for a scenario where a terminal obtains the TA (Target Access Control) of a candidate cell via an instruction, the terminal can obtain the TAs of multiple candidate cells sequentially based on a time order. Taking the case where the terminal accesses candidate cell 1 and obtains the TAs of candidate cell 2 and candidate cell 3 respectively as an example, for instance, at time T1, the terminal receives a DCI (Distributed Control Information Code) indicating the transmission of a preamble to candidate cell 2. Following the DCI's instructions, the terminal sends its assigned preamble at the timing of the random access preamble transmission in candidate cell 2, and then receives the TA of candidate cell 2 from candidate cell 1. After a period of time, at time T2, candidate cell 1 sends a DCI indicating the transmission of a preamble to candidate cell 3. The terminal sends its assigned preamble at the timing of the random access preamble transmission in candidate cell 3, and then receives the TA of candidate cell 3 from candidate cell 1. Optionally, the TA of candidate cell 3 and the TA of candidate cell 2 are indicated using different MAC layer control cells. In other implementations, the TAs of multiple candidate cells can also be obtained simultaneously; in this case, T1 and T2 can be the same.

[0147] As can be seen, in this embodiment, when selecting a target cell for handover from multiple candidate cells, factors such as whether the terminal has a valid TA in the candidate cell, and / or whether the candidate cell has a CG that is allowed to be used (or available) for the terminal are considered. This helps the terminal select a better target cell from multiple candidate cells. For example, a better target cell meets the following conditions: the terminal has a valid TA in the target cell, and the target cell has a CG that is allowed to be used (or available) for the terminal. This effectively improves the handover success rate and reduces service interruption time during the handover process.

[0148] The following section, in conjunction with the handover method shown in Figure 5, elaborates on how the terminal determines the target cell for handover from multiple candidate cells based on whether the terminal has a valid TA for the candidate cell, and / or whether the candidate cell has a CG that is allowed to be used (or available) for the terminal.

[0149] Please refer to Figure 5, which illustrates a flowchart of another switching method. This switching method can be executed by a terminal. As shown in Figure 5, this switching method may include, but is not limited to, the following steps:

[0150] 401. In response to multiple candidate cells meeting the handover execution conditions, the terminal determines whether there is a cell among the multiple candidate cells that meets the first condition.

[0151] In this context, a cell meeting the first condition is one where the terminal has a valid TA for that cell, and that cell is configured with an available CG for the terminal. Having a valid TA for a cell meeting the first condition, and having an available CG for the terminal, allows the terminal to directly access the cell using the valid TA and the configured available CG. This eliminates the need to monitor the cell's downlink control information (DCI) or perform random access, thus improving the handover success rate and reducing service interruption time during handover.

[0152] In one optional implementation, step 402 is executed in response to the existence of a cell that meets the first condition among the multiple candidate cells; and step 403 or step 404 is executed in response to the absence of a cell that meets the first condition among the multiple candidate cells.

[0153] For example, taking multiple candidate cells including candidate cell 1, candidate cell 2, candidate cell 3, and candidate cell 4, in response to candidate cell 1 satisfying its corresponding handover execution condition, candidate cell 2 satisfying its corresponding handover execution condition, candidate cell 3 satisfying its corresponding handover execution condition, and candidate cell 4 not satisfying its corresponding handover execution condition, the multiple candidate cells that satisfy the handover execution condition include candidate cell 1, candidate cell 2, and candidate cell 3. The terminal can determine from candidate cell 1, candidate cell 2, and candidate cell 3 whether there is a cell that satisfies the first condition.

[0154] 402. The terminal will select the cell that meets the first condition as the target cell for handover.

[0155] In one scenario, given that the number of cells satisfying the first condition is N (N is an integer greater than 1), any cell is selected from these N cells, and this selected cell is used as the target cell for handover. It is evident that determining the target cell in this way is simpler and more convenient.

[0156] Alternatively, from N cells that meet the first condition, the cell with the most beams whose signal quality value is greater than or equal to the first threshold can be selected, and this selected cell can be used as the target cell for handover. For example, the terminal can count the number of beams with signal quality values ​​greater than or equal to the first threshold in each cell that meets the first condition, and use the cell with the most counted beams as the target cell for handover. It is evident that in this implementation, the terminal considers the number of beams with signal quality values ​​greater than or equal to the first threshold when selecting the target cell, which is beneficial for the terminal to access a target cell with better signal quality. For example, a target cell with better signal quality is the cell with the most beams whose signal quality value is greater than or equal to the first threshold, thereby further improving the handover success rate and reducing service interruption time during the handover process.

[0157] For example, following the example of step 401, in response to the fact that candidate cell 1 is a cell that meets the first condition, and candidate cell 2 and candidate cell 3 are not cells that meet the first condition, the terminal can use candidate cell 1 as the target cell.

[0158] For example, following the example of step 401, in response to candidate cell 1 and candidate cell 2 being cells that meet the first condition, and candidate cell 3 not meeting the first condition, the terminal may use candidate cell 1 or candidate cell 2 as the target cell. Alternatively, the cell with the most beams whose signal quality value is greater than or equal to the first threshold among candidate cell 1 and candidate cell 2 may be used as the target cell.

[0159] 403. The terminal selects a cell that meets the second condition from multiple candidate cells as the target cell for handover.

[0160] Among them, the cells that meet the second condition include at least one of the following cells:

[0161] ①: The terminal has a valid TA for this cell.

[0162] ②: The cell has configured CGs that are allowed to be used (or are "available") for the terminal; or,

[0163] ③: Among the beams in this cell, the number of beams with signal quality values ​​greater than or equal to the first threshold is the largest.

[0164] In other words, the cells that meet the second condition include cells ①, ②, ③, ① and ②, ① and ③, ② and ③, and ①, ② and ③ as shown above.

[0165] As can be seen, in this implementation, if no cell meets the first condition, the terminal can select a cell that meets the second condition as the target cell for handover. The selection of the target cell considers factors such as whether the terminal has a valid TA in the candidate cell, whether the candidate cell has a CG that is allowed (or available) for the terminal, or the number of beams with a signal quality value greater than or equal to the first threshold. This helps improve the success rate of handover and reduce service interruption time during the handover process.

[0166] 404. The terminal selects any one of the candidate cells that meets the handover execution conditions as the target cell for handover. This implementation method is simpler and more convenient.

[0167] 405. Terminal access to target cell.

[0168] Other related descriptions in steps 401 to 405 can be found in the relevant embodiments in Figure 4, and will not be detailed here.

[0169] As can be seen, in this embodiment, the terminal can prioritize a cell among multiple candidate cells that meets the first condition (a cell meeting the first condition means that the terminal has a valid TA in that cell, and that cell is configured with an available CG for the terminal) as the target cell for handover. This allows the terminal to directly access the target cell using the valid TA and the available CG configured for the terminal in the target cell. The terminal does not need to monitor the downlink control information (DCI) of the target cell, nor does it need to perform random access, which can improve the success rate of handover and reduce the service interruption time during handover. Furthermore, if no cell among the multiple candidate cells meets the first condition, the terminal can secondarily select a cell that meets the second condition as the target cell for handover.

[0170] The foregoing embodiments describe how, after multiple candidate cells meet their respective handover execution conditions, the selection of a target cell considers whether the terminal has a valid TA for the candidate cell and / or whether the candidate cell has a CG that the terminal is allowed to use (or that is available). In other embodiments, this can be extended to a wider range of scenarios. For example, the terminal can first consider whether it has a valid TA for the candidate cell and / or whether the candidate cell has a CG that the terminal is allowed to use (or that is available) to select a cell that meets a first condition from multiple candidate cells, and then further select a cell that meets the handover execution conditions from the cells that meet the first condition as the target cell for handover. Please refer to Figure 6, which shows a flowchart of another handover method. This handover method can be executed by the terminal. As shown in Figure 6, this handover method may include, but is not limited to, the following steps:

[0171] 501. The terminal selects a cell that meets the first condition from multiple candidate cells.

[0172] Among them, a cell that meets the first condition is that the terminal has a valid TA for that cell, and that cell has configured a CG that is allowed to be used (or "available") for the terminal.

[0173] 502. The terminal determines whether there is a cell among the cells that meet the first condition that meets the handover execution conditions.

[0174] For example, taking multiple candidate cells including candidate cell 1, candidate cell 2, candidate cell 3, and candidate cell 4, in response to candidate cell 1 and candidate cell 4 being cells that meet the first condition, and candidate cell 2 and candidate cell 3 not being cells that meet the first condition, the terminal can determine from candidate cell 1 and candidate cell 4 whether there is a cell that meets the handover execution condition.

[0175] In one optional implementation, step 503 is executed in response to the existence of a cell that meets the handover execution conditions among the cells that meet the first condition; step 504 is executed in response to the absence of a cell that meets the handover execution conditions among the cells that meet the first condition.

[0176] 503. The terminal will select the cell that meets the handover execution conditions as the target cell for handover and access the target cell.

[0177] 504. The terminal determines whether there is a cell that meets the delayed handover condition among the cells that meet the first condition.

[0178] Optionally, the delayed switching conditions and the switching execution conditions contain essentially the same content, differing only in the duration of the measurement event indication.

[0179] In one optional implementation, the duration of the measurement event indication in the delayed handover condition is the difference between the duration of the measurement event indication in the handover execution condition and the third threshold. For example, if the duration of the measurement event indication in the handover execution condition is 80 milliseconds (ms) and the third threshold is 15 ms, then the duration of the measurement event indication in the delayed handover condition = 80 - 15 = 65 ms. Continuing with the example of step 502, in response to the handover execution condition corresponding to candidate cell 4 being measurement event A3: the signal quality of the candidate cell is higher than the signal quality of the serving cell by a preset offset, and this needs to last for 80 ms, the terminal finds that the signal quality of candidate cell 4 is already higher than the signal quality of the serving cell by the preset offset, and this has lasted for 70 ms. This does not meet the duration in the handover execution condition (i.e., 80 ms), but it does meet the duration in the delayed handover condition (i.e., 65 ms). The terminal can then determine that candidate cell 4 is a cell that meets the delayed handover condition. Optionally, the third threshold can be configured by the network device or set by the protocol, without limitation.

[0180] In another optional implementation, the duration of the measurement event indication in the delayed handover condition is the product of the duration of the measurement event indication in the handover execution condition and a preset ratio. For example, if the duration of the measurement event indication in the handover execution condition is 80 milliseconds (ms) and the preset ratio is 75%, then the duration of the measurement event indication in the delayed handover condition = 80 * 75% = 60 ms. Continuing with the example of step 502, in response to the handover execution condition corresponding to candidate cell 4 being measurement event A3: the signal quality of the candidate cell is higher than the signal quality of the serving cell by a preset offset, and this needs to last for 80 ms, the terminal finds that the signal quality of candidate cell 4 is already higher than the signal quality of the serving cell by the preset offset, and this has lasted for 70 ms. This does not meet the duration in the handover execution condition (i.e., 80 ms), but it does meet the duration in the delayed handover condition (i.e., 60 ms). The terminal can then determine that candidate cell 4 is a cell that meets the delayed handover condition. Optionally, this preset ratio can be configured by the network device or set by the protocol, and is not limited. If there is a cell that meets the handover delay condition, even if there are other candidate cells that meet the handover execution condition but do not meet the first condition, the terminal postpones the handover execution.

[0181] In one optional implementation, step 505 is executed in response to the existence of a cell that meets the delayed handover condition among the cells that meet the first condition; and step 506 is executed in response to the absence of a cell that meets the delayed handover condition among the cells that meet the first condition.

[0182] 505. The terminal will select the cell that meets the delayed execution conditions as the target cell for handover, and will access the target cell if the target cell meets the handover execution conditions.

[0183] Following the example of step 504, the terminal postpones the handover, waiting for candidate cell 4 to fully meet the handover execution conditions before performing the handover. The terminal then uses the valid TA (Transfer Address) and the CG (Cellular Address) configured for the terminal in candidate cell 4 to access candidate cell 4. If, after the delayed handover, the latest measurement results of candidate cell 4 cause the cell to no longer meet the handover execution conditions, and in response to the availability of other candidate cells that meet the handover execution conditions, the terminal selects the cell that meets the handover execution conditions and performs the handover.

[0184] 506. The terminal selects any one of the multiple candidate cells as the target cell for handover, and accesses the target cell if the handover execution conditions are met.

[0185] As can be seen, in this embodiment, the terminal can first consider whether it has a valid TA (Transfer Attendance) for a candidate cell and / or whether the candidate cell has a CG (Cellular Characteristic) configured for the terminal to be used (or available) to select a cell that meets the first condition from multiple candidate cells. Then, it can further select a cell that meets the handover execution conditions from the cells that meet the first condition as the target cell for handover. Meanwhile, if there is no cell that meets the handover execution conditions among the cells that meet the first condition, but there is a cell that meets the delayed handover conditions, the terminal can postpone the handover execution, wait for the cell to fully meet the handover execution conditions before performing the handover, and can quickly access the network using the cell's valid TA and the CG configured for the terminal in that cell.

[0186] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this disclosure is not limited to the described order of actions, because according to this disclosure, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this disclosure.

[0187] In the above embodiments, the descriptions of each embodiment have their own emphasis, and any multiple embodiments can be used in combination. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0188] Please refer to Figure 7, which is a schematic diagram of the structure of a communication device provided in some embodiments of this disclosure. As shown in Figure 7, the communication device includes a processing unit 601. Optionally, it may also include a communication unit 602.

[0189] In one implementation, the communication device can be a terminal or a device matched with a terminal.

[0190] In response to multiple candidate cells meeting the handover execution conditions, the processing unit 601 is used to determine the target cell for handover from multiple candidate cells based on whether the communication device has a valid TA of the candidate cell, and / or whether the candidate cell has a CG that is allowed to be used (or available) for the communication device; the communication unit 602 is used to access the target cell.

[0191] In one possible implementation, the processing unit 601 is configured to determine the target cell for handover from a plurality of candidate cells based on whether the communication device has a valid TA for the candidate cell and / or whether the candidate cell has configured a CG that is allowed to be used (or available) for the communication device, including: the processing unit 601 is configured to determine whether there is a cell among the plurality of candidate cells that meets a first condition; the cell that meets the first condition is that the communication device has a valid TA for the cell and the cell has configured a CG that is allowed to be used (or available) for the communication device; in response to the existence of a cell that meets the first condition, the processing unit 601 is configured to use the cell that meets the first condition as the target cell for handover.

[0192] In one possible implementation, in response to the number of cells satisfying the first condition being N, the target cell for handover is the cell among the N cells satisfying the first condition that has the largest number of beams with a signal quality value greater than or equal to a first threshold, where N is an integer greater than 1.

[0193] In one possible implementation, after determining whether there is a cell among a plurality of candidate cells that meets the first condition, in response to the absence of a cell that meets the first condition, the processing unit 601 is further configured to select a cell from the plurality of candidate cells that meets the second condition as the target cell for handover; the cell that meets the second condition includes at least one of the following: the communication device has a valid TA for the cell; the cell is configured with a CG that is allowed to be used (or available); or, the number of beams in the cell with a signal quality value greater than or equal to the first threshold is the largest.

[0194] In one possible implementation, after determining whether there is a cell among the multiple candidate cells that meets the first condition, in response to the absence of a cell that meets the first condition, the processing unit 601 is further configured to select any cell from the multiple candidate cells that meets the handover execution condition as the target cell for handover.

[0195] In one possible implementation, before the communication device performs a handover and successfully accesses the target cell, the processing unit 601 is also used to continue to save the TAs of multiple candidate cells.

[0196] In one possible implementation, the candidate cells for continuing to save the TA include at least one of the following: candidate cells where the TA is a valid TA; candidate cells belonging to the same network device as the target cell for handover; or candidate cells indicated by the indication information that the TA needs to be saved. In this implementation, the terminal can selectively save the TAs of some candidate cells, without needing to save the TAs of all candidate cells, which can effectively save storage resources.

[0197] In one possible implementation, the processing unit 601 is configured to determine the target cell for handover from a plurality of candidate cells based on whether the communication device has a valid TA of the candidate cell and / or whether the candidate cell has configured a CG that is allowed to be used (or available) for the communication device, including: the processing unit 601 is configured to select a cell that meets a third condition from the plurality of candidate cells as the target cell for handover; the cell that meets the third condition includes at least one of the following: the communication device has a valid TA of the cell; or the cell has configured a CG that is allowed to be used (or available) for the communication device.

[0198] Please refer to Figure 8, which is a schematic diagram of another communication device provided in some embodiments of this disclosure. This communication device can be a terminal or a device compatible with a terminal.

[0199] Optionally, the communication device may also include a memory 703. The transceiver 701, processor 702, and memory 703 can be connected via a bus 704 or other means. The bus is represented by a thick line in Figure 8. The connection methods between other components are for illustrative purposes only and are not intended to be limiting. Buses can be categorized as address buses, data buses, control buses, etc. For ease of illustration, only one thick line is used in Figure 8, but this does not indicate that there is only one bus or one type of bus.

[0200] In some embodiments of this disclosure, the coupling is an indirect coupling or communication connection between devices, units, or modules, which can be electrical, mechanical, or other forms, used for information exchange between devices, units, or modules. In some embodiments of this disclosure, the specific connection medium between the transceiver 701, processor 702, and memory 703 described above is not limited.

[0201] Memory 703 may include read-only memory and random access memory, and provides instructions and data to processor 702. A portion of memory 703 may also include non-volatile random access memory.

[0202] The processor 702 can be a Central Processing Unit (CPU), but it can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor; optionally, the processor 702 can also be any conventional processor.

[0203] In one alternative implementation, memory 703 is used to store program instructions; processor 702 is used to call the program instructions stored in memory 703 to execute the steps performed by the terminal in the corresponding embodiments of FIG4 to FIG6.

[0204] In some embodiments of this disclosure, the methods provided in some embodiments of this disclosure can be implemented by running a computer program (including program code) capable of performing the steps involved in the methods described above on a general-purpose computing device, such as a computer, which includes processing elements and storage elements such as a CPU, random access memory (RAM), and read-only memory (ROM). The computer program may be recorded on, for example, a computer-readable recording medium, loaded onto the aforementioned computing device via the computer-readable recording medium, and executed therein.

[0205] The communication device provided in some embodiments of this disclosure has similar problem-solving principles and beneficial effects to the embodiment shown in FIG4 of this disclosure. For reference, please refer to the implementation principles and beneficial effects of the method. For the sake of brevity, these will not be repeated here.

[0206] The aforementioned communication device may be, for example, a chip or a chip module.

[0207] Some embodiments of this disclosure also provide a chip including a processor that can execute the relevant steps of the terminal in the method embodiments described in Figures 4 to 6 above.

[0208] In response to multiple candidate cells meeting the handover execution conditions, the chip is used to determine the target cell for handover from multiple candidate cells based on whether the communication device has a valid TA of the candidate cell, and / or whether the candidate cell has a CG that is allowed to be used (or available) for the communication device; the chip is used to access the target cell.

[0209] In one possible implementation, the chip is used to determine whether the communication device has a valid TA for the candidate cell, and / or

[0210] Alternatively, determining whether a candidate cell has a CG that is allowed to be used (or "available") for the communication device, and determining the target cell for handover from multiple candidate cells, includes: the chip determining whether there is a cell that meets a first condition among multiple candidate cells; the cell that meets the first condition is that the communication device has a valid TA for the cell, and the cell has a CG that is allowed to be used (or "available") for the communication device; in response to the existence of a cell that meets the first condition, the chip selecting the cell that meets the first condition as the target cell for handover.

[0211] In one possible implementation, in response to the number of cells satisfying the first condition being N, the target cell for handover is the cell among the N cells satisfying the first condition that has the largest number of beams with a signal quality value greater than or equal to a first threshold, where N is an integer greater than 1.

[0212] In one possible implementation, after determining whether there is a cell satisfying a first condition among a plurality of candidate cells, in response to the absence of a cell satisfying the first condition, the chip is further configured to select a cell satisfying a second condition from the plurality of candidate cells as the target cell for handover; the cell satisfying the second condition includes at least one of the following: the communication device has a valid TA for the cell; the cell is configured with a CG that is allowed to be used (or available) for the communication device; or, the cell has the largest number of beams with signal quality values ​​greater than or equal to a first threshold.

[0213] In one possible implementation, after determining whether there is a cell among multiple candidate cells that meets the first condition, in response to the absence of a cell that meets the first condition, the chip is further configured to select any cell from the multiple candidate cells that meets the handover execution conditions as the target cell for handover.

[0214] In one possible implementation, the chip is also used to continue storing the TAs of multiple candidate cells before the communication device performs a handover and fails to successfully access the target cell.

[0215] In one possible implementation, the candidate cells for continuing to retain the TA include at least one of the following candidate cells: the TA is a candidate cell of a valid TA; the candidate cell belongs to the same network device as the target cell of the handover; or the candidate cell indicated by the indication information that the TA needs to be retained.

[0216] In one possible implementation, the chip is used to determine whether the communication device has a valid TA for the candidate cell, and / or

[0217] Alternatively, determining the target cell for handover from multiple candidate cells includes: the chip selecting a cell that meets a third condition from multiple candidate cells as the target cell for handover; the cell that meets the third condition includes at least one of the following: the communication device has a valid TA for the cell; or the cell has a CG that meets the third condition for the communication device.

[0218] Please refer to Figure 9, which is a schematic diagram of the structure of a chip module provided in some embodiments of this disclosure. This chip module can execute the relevant steps of the cooperative sensing node or sensing control node in the foregoing method embodiments. The chip module includes a communication interface 801 and a chip 802.

[0219] The communication interface is used for internal communication within the chip module, or for communication between the chip module and external devices. The communication interface can also be described as a communication module.

[0220] In one implementation, chip 802 can be used to perform the relevant steps of the terminal in the method embodiments described in Figures 4 to 6 above.

[0221] In response to multiple candidate cells meeting the handover execution conditions, chip 802 is used to determine the target cell for handover from multiple candidate cells based on whether the chip module has a valid TA of the candidate cell, and / or whether the candidate cell has a CG that is allowed to be used (or available) for the chip module; chip 802 is used to access the target cell.

[0222] In one possible implementation, chip 802 is used to determine the target cell for handover from a plurality of candidate cells based on whether the chip module has a valid TA for the candidate cell, and / or whether the candidate cell has a CG that is allowed to be used (or available) for the chip module, including: chip 802 is used to determine whether there is a cell among the plurality of candidate cells that meets a first condition; the cell that meets the first condition is that the chip module has a valid TA for the cell, and the cell has a CG that is allowed to be used (or available) for the chip module; in response to the existence of a cell that meets the first condition, chip 802 is used to select the cell that meets the first condition as the target cell for handover.

[0223] In one possible implementation, in response to the number of cells satisfying the first condition being N, the target cell for handover is the cell among the N cells satisfying the first condition that has the largest number of beams with a signal quality value greater than or equal to a first threshold, where N is an integer greater than 1.

[0224] In one possible implementation, after determining whether there is a cell satisfying a first condition among a plurality of candidate cells, in response to the absence of a cell satisfying the first condition, chip 802 is further configured to select a cell satisfying a second condition from the plurality of candidate cells as the target cell for handover; the cell satisfying the second condition includes at least one of the following: the chip module has a valid TA for the cell; the cell is configured with a CG that is allowed to be used (or available) for the chip module; or, the cell has the largest number of beams with signal quality values ​​greater than or equal to a first threshold.

[0225] In one possible implementation, after determining whether there is a cell among multiple candidate cells that meets the first condition, in response to the absence of a cell that meets the first condition, chip 802 is further configured to select any cell from the multiple candidate cells that meets the handover execution conditions as the target cell for handover.

[0226] In one possible implementation, before the chip module performs a handover and successfully accesses the target cell, the chip 802 is also used to continue to save the TAs of multiple candidate cells.

[0227] In one possible implementation, the candidate cells for continuing to retain the TA include at least one of the following candidate cells: the TA is a candidate cell of a valid TA; the candidate cell belongs to the same network device as the target cell of the handover; or the candidate cell indicated by the indication information that the TA needs to be retained.

[0228] In one possible implementation, chip 802 is used to determine the target cell for handover from a plurality of candidate cells based on whether the chip module has a valid TA of the candidate cell, and / or whether the candidate cell has a CG that is allowed to be used (or available) for the chip module, including: chip 802 is used to select a cell that meets a third condition from a plurality of candidate cells as the target cell for handover; the cell that meets the third condition includes at least one of the following: the chip module has a valid TA of the cell; or the cell has a CG that is allowed to be used (or available) for the chip module.

[0229] Optionally, the chip module may also include a storage module 803 and a power module 804. The storage module 803 is used to store data and instructions. The power module 804 is used to provide power to the chip module.

[0230] All embodiments of this disclosure can be executed individually or in combination with other embodiments, and are all considered to be within the scope of protection claimed by this disclosure.

[0231] For various devices and products applied to or integrated into chip modules, each of its modules can be implemented using hardware methods such as circuits. Different modules can be located in the same component (e.g., chip, circuit module, etc.) or different components of the chip module. Alternatively, at least some modules can be implemented using software programs that run on the processor integrated inside the chip module, while the remaining (if any) modules can be implemented using hardware methods such as circuits.

[0232] This disclosure also provides a computer-readable storage medium storing one or more instructions adapted for loading by a processor and executing the methods provided in the above-described method embodiments.

[0233] This disclosure also provides a computer program product containing a computer program or instructions, which, when run on a computer, causes the computer to perform the methods provided in the above-described method embodiments.

[0234] It should be noted that, for the sake of simplicity, the above embodiments are all described as a series of actions. Those skilled in the art should understand that this disclosure is not limited to the described order of actions, as some steps in the embodiments of this disclosure can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions, steps, modules, or units involved are not necessarily essential to the embodiments of this disclosure.

[0235] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0236] The steps of the methods or algorithms described in this disclosure can be implemented in hardware or by a processor executing software instructions. The software instructions can consist of corresponding software modules, which can be stored in RAM, flash memory, ROM, erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disks, portable hard disks, read-only optical discs (CD-ROMs), or any other form of storage medium well known in the art. An exemplary storage medium is coupled to a processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and storage medium can reside in an ASIC. Additionally, the ASIC can reside in a terminal device or management device. Alternatively, the processor and storage medium can exist as discrete components in the terminal device or management device.

[0237] Those skilled in the art will recognize that, in one or more of the examples above, the functions described in the embodiments of this disclosure can be implemented, in whole or in part, by software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. This computer program product includes one or more computer instructions. When these computer program instructions are loaded and executed on a computer, all or part of the flow or function according to the embodiments of this disclosure is generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available media can be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., digital video discs (DVDs)), or semiconductor media (e.g., solid-state disks (SSDs)).

[0238] Regarding the modules / units included in the various devices and products described in the above embodiments, they can be software modules / units, hardware modules / units, or a combination of both. For example, for various devices and products applied to or integrated into a chip, all of their modules / units can be implemented using hardware methods such as circuits, or at least some modules / units can be implemented using software programs that run on a processor integrated within the chip, while the remaining (if any) modules / units can be implemented using hardware methods such as circuits; for various devices and products applied to or integrated into a chip module, all of their modules / units can be implemented using hardware methods such as circuits, and different modules / units can be located in the same component (e.g., chip, circuit module, etc.) or different components of the chip module, or at least some modules / units can be implemented using hardware methods such as circuits. The components can be implemented using software programs that run on the processor integrated within the chip module. The remaining (if any) modules / units can be implemented using hardware methods such as circuits. For various devices and products applied to or integrated into the terminal, each of its components / units can be implemented using hardware methods such as circuits. Different modules / units can be located in the same component (e.g., chip, circuit module, etc.) or in different components within the terminal. Alternatively, at least some modules / units can be implemented using software programs that run on the processor integrated within the terminal, while the remaining (if any) modules / units can be implemented using hardware methods such as circuits.

[0239] The above detailed embodiments further illustrate the purpose, technical solutions, and beneficial effects of the embodiments of this disclosure. It should be understood that the above are merely specific embodiments of the embodiments of this disclosure and are not intended to limit the protection scope of the embodiments of this disclosure. Any modifications, equivalent substitutions, improvements, etc., made on the basis of the technical solutions of the embodiments of this disclosure should be included within the protection scope of the embodiments of this disclosure.

Claims

1. A switching method, characterized in that, The method includes: In response to multiple candidate cells meeting the handover execution conditions, the target cell for handover is determined from the multiple candidate cells based on whether the terminal has a valid time advance for the candidate cells, and / or whether the candidate cells have been configured with an authorized configuration for the terminal. Access the target cell.

2. The method according to claim 1, characterized in that, The step of determining the target cell for handover from the plurality of candidate cells based on whether the terminal has a valid timing advance for the candidate cell, and / or whether the candidate cell has been configured with a configuration authorization that the terminal is allowed to use, includes: Determine whether there is a cell among the plurality of candidate cells that meets the first condition; the cell that meets the first condition is that the terminal has a valid timing advance for the cell, and the cell has been configured with a configuration authorization that the terminal is allowed to use; In response to the existence of a cell that meets the first condition, the cell that meets the first condition is selected as the target cell for handover.

3. The method according to claim 2, characterized in that, In response to the number of cells satisfying the first condition being N, the target cell for handover is the cell among the N cells satisfying the first condition that has the most beams with a signal quality value greater than or equal to a first threshold, where N is an integer greater than 1.

4. The method according to claim 2, characterized in that, After determining whether there is a cell satisfying the first condition among the plurality of candidate cells, the method further includes: In response to the absence of a cell satisfying the first condition, a cell satisfying the second condition is selected from the plurality of candidate cells as the target cell for handover; the cell satisfying the second condition includes at least one of the following cells: The terminal has the effective timing advance capability for this cell; The cell has configured the terminal with the allowed configuration licenses; or, Among the beams in this cell, the number of beams with signal quality values ​​greater than or equal to the first threshold is the largest.

5. The method according to claim 2, characterized in that, After determining whether there is a cell satisfying the first condition among the plurality of candidate cells, the method further includes: In response to the absence of a cell satisfying the first condition, any cell that satisfies the handover execution conditions is selected from the plurality of candidate cells as the target cell for handover.

6. The method according to any one of claims 1 to 5, characterized in that, The method further includes: Before the terminal performs a handover and successfully accesses the target cell, the time advance of the multiple candidate cells is maintained.

7. The method according to claim 6, characterized in that, The candidate cells for which the timing is advanced are continued to be saved include at least one of the following candidate cells: Pre-time advance is a candidate cell for effective pre-time advance; The candidate cell belonging to the same network device as the target cell for the handover; or... The instruction information indicates that candidate cells need to be saved in advance at regular intervals.

8. The method according to claim 1, characterized in that, The step of determining the target cell for handover from the plurality of candidate cells based on whether the terminal has a valid timing advance for the candidate cell, and / or whether the candidate cell has been configured with a configuration authorization that the terminal is allowed to use, includes: From the plurality of candidate cells, a cell that meets the third condition is selected as the target cell for handover; the cell that meets the third condition includes at least one of the following cells: The terminal has a valid timing advance for that cell; or, The cell has configured the terminals with the allowed configuration licenses.

9. A communication device, characterized in that, Includes units or modules for implementing the method of any one of claims 1 to 8.

10. A communication device, characterized in that, It includes a processor, a memory, and a computer program or instructions stored in the memory, wherein the processor executes the computer program or instructions to cause the communication device to perform the method of any one of claims 1 to 8.

11. A chip, characterized in that, The chip includes at least one processor for executing program instructions to perform the steps of the method as claimed in any one of claims 1 to 8.

12. A chip module, comprising a communication interface and a chip, characterized in that, The communication interface is used for internal communication within the chip module, or for communication between the chip module and external devices; the chip is used to perform the steps of the method as described in any one of claims 1 to 8.

13. A non-volatile computer-readable storage medium, characterized in that, It stores a computer program or instructions that, when executed, implement the steps of the method as described in any one of claims 1 to 8.

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