Cell measurement method and apparatus

Abstract

This application discloses a cell measurement method and apparatus. The method includes a step in which a first network device determines first indication information. The first indication information indicates at least one candidate cell and a first cell set corresponding to a first candidate cell among the at least one candidate cell. The first cell set includes at least one cell. The first network device transmits the first indication information. The terminal device receives the first indication information. The terminal device measures the cells within the first cell set based on the first indication information. The serving cell of the terminal device is the first candidate cell. In this way, the range of cells measured and evaluated by the terminal device is specified, and the cell handover efficiency and the cell handover success rate are improved.

Description

Technical Field

[0001] This application claims the priority of Chinese Patent Application No. 202210880569.6, titled "Cell Measurement Method and Apparatus", filed with the China National Intellectual Property Administration on July 25, 2022, and the entire content of the Chinese patent application is incorporated herein by reference in its entirety.

[0002] This application relates to the field of wireless communication technologies, and in particular, to a cell measurement method and apparatus.

Background Art

[0003] In a wireless communication network, it is necessary to perform continuous cell handovers in many scenarios. For example, Conditional Primary Secondary Cell Addition / Change (CPAC) or Conditional Layer 1 or Layer 2 Handover is executed. Layer 1 is the physical layer, and Layer 2 includes the Media Access Control (MAC) layer, Radio Link Control (RLC) layer, and Packet Data Convergence Control (PDCP) layer. During CPAC or Conditional L1 / L2 handover, after CPAC or Conditional L1 / L2 handover is completed once, the terminal device may not release the CPAC configuration or L1 / L2 pre-configuration information and may continue to maintain the CPAC configuration or L1 / L2 pre-configuration information. Therefore, in some cases, the network may need to configure more candidate cells for the terminal device to perform continuous cell handovers. As the terminal device moves, not all candidate cells are necessarily suitable for the terminal device when performing the cell handover process. In this case, if the terminal device measures or evaluates all candidate cells to determine the target cell for handover, there are problems such as an unclear range of cells to be measured, low cell handover efficiency, and an increase in unnecessary power overhead.

Summary of the Invention

Means for Solving the Problems

[0004] Embodiments of the present application provide a cell measurement method and apparatus to specify the range of cells measured and evaluated by a terminal device and to improve cell handover efficiency and cell handover success rate.

[0005] According to the first aspect, a cell measurement method is provided. This method may be executed by a terminal device or may be executed by a chip used in the terminal device. Hereinafter, an example in which this method is executed by a terminal device will be used for explanation. The terminal device receives first indication information, and the first indication information indicates at least one candidate cell and a first cell set corresponding to a first candidate cell among the at least one candidate cell, and the first cell set includes at least one cell. The terminal device measures the cells in the first cell set based on the first indication information, and the serving cell of the terminal device is the first candidate cell.

[0006] In this embodiment of the present application, it can be seen that the first indication information is obtained, and the first indication information indicates at least one candidate cell and a first cell set corresponding to a first candidate cell among the at least one candidate cell. The terminal device performs cell measurement based on the first cell set indicated by the first indication information. In this process, in order to accurately determine the range of cells measured and evaluated by the terminal device during cell handover and improve the handover efficiency, the first cell set corresponding to the serving cell is determined. In addition, the cells measured and evaluated by the UE are not limited to at least one candidate cell configured for the terminal device, and the cell handover success rate of the terminal device can be improved.

[0007] In a possible design, the at least one candidate cell is at least one candidate primary secondary cell for conditional primary secondary cell addition CPA or conditional primary secondary cell change CPC.

[0008] In this embodiment of the present application, the cell measurement method is applied to the conditional primary secondary cell addition CPA or the conditional primary secondary cell change CPC scenario. Thus, in the CPA or CPC scenario, especially when there is a continuous inter-cell handover, the range of cells measured and evaluated by the terminal device can be determined based on the serving cell of the terminal device, and the cell handover efficiency and the cell handover success rate can be improved.

[0009] In one possible design, at least one candidate cell is at least one candidate primary cell for a layer 1 / layer 2 handover.

[0010] In this embodiment of the present application, the cell measurement method is applied to the layer 1 / layer 2 handover scenario. Thus, in the layer 1 / layer 2 scenario, especially when there is a continuous inter-cell handover, the range of cells measured and evaluated by the terminal device can be determined based on the serving cell of the terminal device, and the cell handover efficiency and the cell handover success rate can be increased.

[0011] In one possible design, the first indication information indicating the first cell set corresponding to the first candidate cell among at least one candidate cell includes that the first indication information indicates the first cell set corresponding to the first candidate cell by indicating the physical cell identifier PCI of at least one cell, that the first indication information indicates the first cell set corresponding to the first candidate cell by indicating the configuration identifier of at least one cell, where the configuration identifier is associated with the configuration of the candidate cell among at least one candidate cell, or that the first indication information indicates the first cell set corresponding to the first candidate cell by using the bitmap indication information.

[0012] In one possible design, at least one cell included in the first cell set is a cell among at least one candidate cell.

[0013] In this embodiment of the present application, the cells in the first cell set are at least one of the candidate cells. In this case, the cells measured and evaluated by the terminal device during handover are usually fewer than the set including all candidate cells. Thus, the number of cells that need to be measured and evaluated by the terminal device during cell handover can be reduced, the cell handover efficiency can be improved, and the power consumption for measuring and evaluating cells can be reduced.

[0014] According to a second aspect, a cell measurement method is provided. The method may be executed by a network device or may be executed by a chip used in the network device. Hereinafter, an example in which the method is executed by a network device is used for explanation. The network device determines first indication information, where the first indication information indicates at least one candidate cell and a first cell set corresponding to a first candidate cell among the at least one candidate cell, and the first cell set includes at least one cell. The network device transmits the first indication information.

[0015] In a possible design, the at least one candidate cell is at least one candidate primary secondary cell for conditional primary secondary cell addition CPA or conditional primary secondary cell change CPC.

[0016] In a possible design, the at least one candidate cell is at least one candidate primary cell for layer 1 / layer 2 handover.

[0017] In one possible design, the first indication information indicating a first cell set corresponding to a first candidate cell among at least one candidate cell includes: the first indication information indicating the first cell set corresponding to the first candidate cell by indicating the physical cell identifier (PCI) of at least one cell; the first indication information indicating the first cell set corresponding to the first candidate cell by indicating the configuration identifier of at least one cell, where the configuration identifier is associated with the configuration of the candidate cell among at least one candidate cell; or the first indication information indicating the first cell set corresponding to the first candidate cell by using bitmap indication information.

[0018] In one possible design, at least one cell included in the first cell set is a cell among at least one candidate cell.

[0019] In one possible design, the method further includes determining a first cell set corresponding to the first candidate cell based on at least one of the following information: a measurement report reported by a terminal device, network topology information, network deployment information, and statistical information.

[0020] In one possible design, before the step of determining a first cell set corresponding to the first candidate cell, the method further includes: sending a request message to a second network device to request using a cell of the second network device as one of at least one candidate cell; receiving feedback information of the second network device; and determining whether to use a cell of the second network device as one of at least one candidate cell based on the feedback information.

[0021] In one possible design, the feedback information further indicates a second cell set corresponding to the cells of the second network device, and the method further includes determining a corresponding first cell set based on the second cell set when the cells of the second network device are used as the first candidate cells.

[0022] According to a third aspect, a communication method is provided. The method may be executed by a terminal device or may be executed by a chip used in the terminal device. Hereinafter, an example in which the method is executed by a terminal device is used for description. The method includes a step in which the terminal device receives a first message, and the first message includes configuration information of candidate cells. When a first condition is satisfied, the terminal device sends a second message to a first network device, and the second message is used to request to update the configuration information of the candidate cells. The first condition includes at least one of the following, that is, the signal quality of the serving cell is less than or equal to a first threshold, the number of detectable candidate cells is less than or equal to a first number, or the signal quality of the candidate cells is less than or equal to a second threshold.

[0023] In this embodiment of the present application, when the first condition is satisfied to request to update the configuration information of the candidate cells, the terminal device may be triggered to send a second message to the first network device. In this way, since the terminal device actively requests the network device to update the configuration information of the candidate cells, the terminal device can timely obtain the most accurate configuration information of the candidate cells in order to perform a cell handover. Thereby, the probability of successful cell handover is increased, and the delay of cell handover caused by the inability to timely obtain the effective configuration information of the candidate cells is reduced.

[0024] According to a fourth aspect, a communication method is provided. The method may be executed by a terminal device or may be executed by a chip used in the terminal device. In the following, an example in which the method is executed by a terminal device is used for explanation. The method includes a step in which the terminal device receives a first message, and the first message includes configuration information of a candidate cell. When a second condition is satisfied, the terminal device is triggered to send a measurement report to a first network device, the measurement report includes the signal quality of the candidate cell, and the second condition includes at least one of the following, that is, the signal quality of the serving cell is less than or equal to a second threshold, the number of candidate cells that can be detected by the terminal device is less than or equal to a second number, the signal quality of the candidate cell is less than or equal to a third threshold, the serving cell is switched to a first cell, where the first cell is a cell within a first cell set, the switching, or the signal quality of one or more cells other than the candidate cell is greater than or equal to a fourth threshold.

[0025] In this embodiment of the present application, when the second condition is satisfied, the terminal device may be triggered to send a measurement report to the first network device. The measurement report is used by the first network device as a criterion for how to update the configuration information of the candidate cell. In this way, the terminal device actively sends a measurement report to the network device. Compared with the prior art in which the measurement report is fed back based on a measurement configuration or the measurement report is sent periodically, the measurement report can be fed back more flexibly and timely, so that the network device can more quickly and accurately determine a solution for updating the configuration information of the candidate cell. Furthermore, the success rate of the cell handover process is increased.

[0026] In one possible design, the configuration information of the candidate cell is conditional primary-secondary cell addition (CPA) or conditional primary-secondary cell change (CPC) configuration information, and the second message is used to update the CPA or CPC configuration information, or the configuration information of the candidate cell is the configuration information of the candidate cell for layer 1 / layer 2 handover, and the second message is used to request to update the layer 1 / layer 2 handover configuration information.

[0027] According to the method used in this embodiment of the present application, in the CPA or CPC scenario, especially when there is a continuous inter-cell handover, compared with the general situation where CPAC configuration information (that is, CPA or CPC configuration information) can be obtained only when the MN determines to add or change the SN, the network device can update the CPAC configuration information more timely based on the received measurement report, and can improve the SN handover efficiency and the SN handover success rate. Similarly, compared with the general situation where a measurement report can be obtained only when the CU distributes the measurement configuration and the layer 1 / layer 2 handover configuration information is updated, in the method of this embodiment of the present application, the layer 1 / layer 2 handover configuration information can be updated more quickly and timely, and the DU handover efficiency and the DU handover success rate can be further improved.

[0028] In one possible design, the method further includes a step in which the terminal device receives a third message, the third message instructs the terminal device to switch to a target cell, and the target cell does not belong to the candidate cell. The terminal device switches to the target cell and then executes any one of the following: that is, considering that the configuration information of the candidate cell is valid or stored, or determining whether the configuration information of the candidate cell is valid or invalid based on the instruction information from the first network device.

[0029] In this embodiment of the present application, in order to reduce the resource overhead caused by re - distributing the configuration information of the candidate cell when the terminal device is switched back to the target cell within the candidate cell, when the terminal device receives the indication information instructing it to switch to a target cell that does not belong to the candidate cell, the terminal device can determine, based on the default information, that the configuration information of the candidate cell is valid or is considered to be stored. Alternatively, since the terminal device determines the configuration information of the candidate cell based on the indication information of the first network device, the flexibility of the terminal device to process the configuration information of the candidate cell can be enhanced.

[0030] In one possible design, the method further includes a step in which the terminal device triggers a Radio Resource Control (RRC) re - establishment process, and the cell selected in the RRC re - establishment process belongs to the first network device. The terminal device considers the configuration information of the candidate cell to be valid or to be stored.

[0031] In this embodiment of the present application, when the terminal device triggers an RRC re - establishment process and the selected cell belongs to the first network device, this means that the serving cell of the terminal device does not change, or the terminal device is close to the original serving cell, and the previously received configuration information of the candidate cell may continue to be held or used. Thereby, the resource overhead for re - transmitting the configuration information of the candidate cell is reduced.

[0032] According to a fifth aspect, a communication method is provided. This method may be executed by a first network device or may be executed by a chip used in the first network device. Hereinafter, an example in which this method is executed by a first network device will be used for explanation. This method includes a step in which the first network device determines configuration information of a candidate cell. The first network device transmits a first message, and the first message includes configuration information of the candidate cell. The first network device receives the first message or a measurement report. The first message is used to request updating the configuration information of the candidate cell, and the measurement report includes the signal quality of the candidate cell.

[0033] In a possible design, the configuration information of the candidate cell is conditional primary secondary cell addition CPA or conditional primary secondary cell change CPC configuration information, and the first message is used to request updating the CPA or CPC configuration information, or the configuration information of the candidate cell is the configuration information of the candidate cell for layer 1 / layer 2 handover, and the first message is used to request updating the layer 1 / layer 2 handover configuration information.

[0034] According to a sixth aspect, a communication device is provided. This device includes a receiving module configured to receive first indication information, where the first indication information indicates at least one candidate cell and a first cell set corresponding to a first candidate cell among the at least one candidate cell, and the first cell set includes at least one cell, and a processing module used by a terminal device to measure cells within the first cell set based on the first indication information, where the serving cell of the terminal device is the first candidate cell.

[0035] In a possible design, the at least one candidate cell is at least one candidate primary secondary cell for conditional primary secondary cell addition CPA or conditional primary secondary cell change CPC.

[0036] In one possible design, at least one candidate cell is at least one candidate primary cell for layer 1 / layer 2 handover.

[0037] In one possible design, the first indication information indicates at least one cell in the first cell set in any one of the following ways, that is, the physical cell identifier (PCI) of at least one cell, the configuration identifier of at least one cell, where the configuration identifier is associated with the configuration of the candidate cell among at least one candidate cell, or the bitmap indication information.

[0038] In one possible design, at least one cell included in the first cell set is a cell among at least one candidate cell.

[0039] According to a seventh aspect, a communication device is provided. The device includes a processing module configured to determine first indication information, where the first indication information indicates at least one candidate cell and a first cell set corresponding to a first candidate cell among the at least one candidate cell, and the first cell set includes at least one cell, and a transmission module configured to transmit the first indication information.

[0040] In one possible design, at least one candidate cell is at least one candidate primary-secondary cell for conditional primary-secondary cell addition (CPA) or conditional primary-secondary cell change (CPC).

[0041] In one possible design, at least one candidate cell is at least one candidate primary cell for layer 1 / layer 2 handover.

[0042] In one possible design, the first indication information indicates at least one cell in the first cell set in at least one of the following ways, namely, the physical cell identifier (PCI) of at least one cell, a configuration identifier of at least one cell, where the configuration identifier is associated with the configuration of a candidate cell among at least one candidate cell, or bitmap indication information.

[0043] In one possible design, at least one cell included in the first cell set is a cell among at least one candidate cell.

[0044] According to an eighth aspect, a communication device is provided. The device includes a receiving module configured to receive a first message, where the first message includes configuration information of candidate cells, and a transmitting module configured to transmit a second message to a first network device when a first condition is satisfied, where the second message is used to request updating the configuration information of candidate cells, and the first condition includes at least one of the following, namely, the signal quality of a serving cell is less than or equal to a first threshold, the number of detected candidate cells is less than or equal to a first number, or the signal quality of a candidate cell is less than or equal to a second threshold.

[0045] According to a ninth aspect, a communication device is provided. The device includes a receiving module configured to receive a first message, where the first message includes configuration information of a candidate cell, and a transmitting module configured to trigger transmission of a measurement report to a first network device when a second condition is satisfied. The measurement report includes the signal quality of the candidate cell, and the second condition includes at least one of the following: the signal quality of the serving cell is below a second threshold; the number of detectable candidate cells is below a second number; the signal quality of the candidate cell is below a third threshold; the serving cell is switched to a first cell, where the first cell is a cell within a first cell set; or the signal quality of one or more cells other than the candidate cell is above a fourth threshold.

[0046] In a possible design, the configuration information of the candidate cell is conditional primary secondary cell addition (CPA) or conditional primary secondary cell change (CPC) configuration information, the second message is used to update the CPA or CPC configuration information, or the configuration information of the candidate cell is the configuration information of the candidate cell for layer 1 / layer 2 handover, and the second message is used to request updating the layer 1 / layer 2 handover configuration information.

[0047] In a possible design, the receiving module is further configured to receive a third message, where the third message instructs the device to switch to a target cell, and the target cell does not belong to the candidate cells. The device further includes a processing module configured to perform a handover to the target cell and perform either one of the following: consider the configuration information of the candidate cell to be valid or stored; or determine whether the configuration information of the candidate cell is valid or invalid based on the instruction information from the first network device.

[0048] In one possible design, the apparatus is configured to trigger a radio resource control (RRC) re - establishment process and to assume that the cell selected in the RRC re - establishment process belongs to a first network device, and to assume that the configuration information of the candidate cell is valid or stored, and includes a processing module.

[0049] According to a tenth aspect, a communication apparatus is provided. The apparatus includes a processing module configured to determine configuration information of a candidate cell, a transmission module configured to transmit a first message, where the first message includes the configuration information of the candidate cell, and a reception module configured to receive the first message or a measurement report, where the first message is used to request updating the configuration information of the candidate cell and the measurement report includes the signal quality of the candidate cell.

[0050] In one possible design, the configuration information of the candidate cell is conditional primary secondary cell addition (CPA) or conditional primary secondary cell change (CPC) configuration information, and the first message is used to request updating the CPA or CPC configuration information, or the configuration information of the candidate cell is the configuration information of a candidate cell for a layer 1 / layer 2 handover, and the first message is used to request updating the layer 1 / layer 2 handover configuration information.

[0051] According to an eleventh aspect, an embodiment of the present application includes a memory configured to store instructions, and at least one processor connected to the memory, and provides a terminal device, where when the at least one processor executes the instructions, the instructions enable the processor to execute the method according to any one of the first aspect, the third aspect, or the fourth aspect.

[0052] According to a twelfth aspect, an embodiment of the present application includes a memory configured to store instructions, Provided is a network device including at least one processor connected to a memory. When the at least one processor executes an instruction, the instruction enables the processor to execute either the second mode or the fifth mode.

[0053] According to a thirteenth aspect, an embodiment of the present application provides a chip system including a processor. The processor is connected to a memory, and the memory is configured to store a program or instructions. When the program or instructions are executed by the processor, the chip system can implement any one of the first mode to the fifth mode.

[0054] Optionally, the chip system further includes an interface circuit configured to exchange code instructions with the processor.

[0055] Optionally, there may be one or more processors in the chip system, and the processor may be implemented by hardware or software. When the processor is implemented by hardware, the processor may be a logic circuit, an integrated circuit, etc. When the processor is implemented by software, the processor may be a general-purpose processor and is implemented by reading software code stored in a memory.

[0056] Optionally, there may be one or more memories in the chip system. The memory may be integrated with the processor or may be arranged separately from the processor. This is not limited in the present application. For example, the memory may be a non-volatile processor, such as a read-only memory ROM. The memory and the processor may be integrated on the same chip or may be separately arranged on different chips. The type of memory and the way of arranging the memory and the processor are not specifically limited in the present application.

[0057] According to the 14th aspect, an embodiment of the present application provides a computer-readable storage medium. This computer-readable storage medium stores a computer program or instructions. When the computer program or instructions are executed, the computer can execute any one of the methods according to the 1st to 5th aspects.

[0058] According to the 15th aspect, an embodiment of the present application provides a computer program product. When a computer reads and executes this computer program product, the computer can execute any one of the possible implementations according to the 1st to 5th aspects.

[0059] According to the 16th aspect, an embodiment of the present application provides a communication system. This communication system includes the device according to the 6th aspect and / or the device according to the 7th aspect, or this communication system includes the device according to the 8th aspect or the 9th aspect and / or the device according to the 10th aspect.

[0060] To more clearly explain the embodiments of the present application or the technical solutions of the prior art, the accompanying drawings for explaining the embodiments will be briefly described below.

Brief Description of the Drawings

[0061]

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Embodiments for Carrying Out the Invention

[0062] In the specification, claims, and appended drawings of this application, terms such as "first", "second", "third", and "fourth" are intended to distinguish different objects and do not indicate a specific order. In addition, terms such as "comprising", "having", and any other variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device comprising a series of steps or units is not limited to the listed steps or units, and may optionally include steps or units not listed, or may optionally include other specific steps or units of the process, method, product, or device.

[0063] As used herein, "embodiment" means that a particular feature, structure, or characteristic described in combination with an embodiment may be included in at least one embodiment of this application. The phrase shown in various places in this specification may not necessarily refer to the same embodiment, nor is it an independent embodiment exclusive of other embodiments or an arbitrarily selected embodiment. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments. It is also possible to use combinations of separate embodiments in this document.

[0064] "A plurality of" means two or more. The term "and / or" describes the relationship for describing related objects and indicates that three relationships can exist. For example, A and / or B can indicate the following three cases: namely, when only A exists, when both A and B exist, and when only B exists. The character " / " usually indicates the "or" relationship between related objects.

[0065] Hereinafter, the terms of the embodiments of this application will be first described with reference to the drawings.

[0066] Mobility: Mobility management is to change the serving cell of the terminal device (user equipment, UE) so that the UE can enjoy network services no matter how it moves within the network coverage area. Mobility in the connected mode is realized by handover.

[0067] Dual Connectivity: Dual Connectivity (DC) or Multi-Radio Dual Connectivity (MR-DC) means that the UE can communicate with two base stations simultaneously. One of the two base stations may be a New Radio (NR) base station, and the other may be a Long Term Evolution (LTE) base station. Alternatively, both of the two base stations are NR base stations. Among the two base stations, the base station that provides the control plane connection to the core network is called the Master Node (MN), and the base station that does not provide the control plane connection to the core network is called the Secondary Node (SN) (this may also be called the secondary base station).

[0068] Dual connectivity and carrier aggregation: For details, refer to FIG. 1. FIG. 1 is a diagram of the structure of dual connectivity according to an embodiment of the present application. When dual connectivity is combined with carrier aggregation (CA), each base station may include one cell group (CG). The cell group served by the master station is the master cell group (MCG). The cell group served by the secondary station is the secondary cell group (SCG). The master cell group may include a primary cell (PCell) and a secondary cell (SCell), and the secondary cell group may include a primary secondary cell (PSCell) and a secondary cell (SCell).

[0069] Base Station Architecture: Figure 2 is a diagram of the NG-RAN architecture according to an embodiment of the present application. As shown in Figure 2(a), the 5G Radio Access Network (NG-RAN) can be a distributed unit (DU)-central unit (CU) split architecture. As shown in Figure 2(b), the DU includes a physical layer (mainly the high-layer physical layer, i.e., high-PHY), a media access control (MAC) layer, and a radio link control (RLC) layer, and the CU includes a packet data convergence control (PDCP) layer and a radio resource control (RRC) layer. The NG-RAN may further include an active antenna processing unit (AAU), and the AAU includes a low-layer physical layer (i.e., low-PHY), a radio frequency (RF) unit, and an antenna. Based on protocol stack layering, layer 1 (L1) is the physical layer, layer 2 (L2) includes the MAC layer, the RLC layer, and the PDCP layer, and layer 3 (L3) is the RRC layer.

[0070] Handover: The handover is completed on the RRC layer. Figure 3 is a diagram of the handover process according to an embodiment of the present application. The specific procedures are shown below.

[0071] 1. The source base station (gNB) performs a measurement configuration on the UE.

[0072] 2. The UE reports measurement results based on the measurement configuration, and the measurement results of the UE are used to assist the source base station when making a handover decision.

[0073] 3. The source base station makes a handover decision based on the handover algorithm of the source base station with reference to the measurement results reported by the UE.

[0074] 4. The source base station sends a handover request to the target base station and transfers the relevant information necessary for handover preparation, which includes at least the identifier of the target cell, the key, the ID of the terminal in the source cell, the basic access stratum configuration, etc.

[0075] 5. The target base station performs access control.

[0076] 6. The target base station prepares for the L1 / L2 handover, sends a handover request acknowledgement (Acknowledge, ACK) message to the source base station, and the handover command sent to the UE is included in the ACK message in the form of an RRC container.

[0077] 7. The source base station triggers the handover (HandOver, HO) and sends a handover command (HO Command) to the UE. The handover command is generated by the target base station, and the transparent transmission of the handover command is executed via the source base station (specifically, the handover command may be sent using an RRC reconfiguration message containing synchronization information). The source base station can perform the necessary encryption and integrity protection for the message. The handover command includes the information necessary to access the target cell, including at least the identifier of the target cell, the new ID of the UE, and the security algorithm identifier of the target base station, and can further carry dedicated random access channel (Random Access Channel, RACH) resources for accessing the target cell.

[0078] 8. The source base station sends a sequence number status transfer to the target base station.

[0079] 9. After receiving the handover command, the UE performs synchronization with the target base station to communicate with the target base station after the handover is successful.

[0080] 10. The target base station returns a Random Access Response (RAR) and performs uplink resource allocation (Uplink grant) and Timing Advance (TA).

[0081] 11. The UE sends an RRC reconfiguration complete message to the target base station to confirm the completion of the handover process to the target base station. This message may further be sent together with an uplink buffer status report (Buffer Status Report, BSR). The target base station confirms that the handover process has been successful by receiving the RRC reconfiguration complete message. In this case, the target base station can start sending data to the terminal.

[0082] 12. The target base station notifies the Authentication Management Function (AMF) that the cell has been changed, triggers the core network (5GC) to switch the downlink (DL) data path to the target base station, and sends a path switch request message to the AMF to establish an NG-C interface to the target base station. In this case, the air interface switch has been completed successfully.

[0083] 13. The AMF sends a user plane (User Plane, UP) update request message to the User Plane Function (UPF).

[0084] 14. The UPF switches the DL data path to the target base station. The UPF can send one or more end markers to the source cell and then release the UP resources or transport network layer resources among the remaining source base stations.

[0085] 15. The UPF sends a UP update response message to the AMF.

[0086] 16. The AMF sends a path switch ACK message to the target base station.

[0087] 17. After receiving the path switch ACK message, the target base station notifies the source base station that the handover has succeeded and sends a UE context release message to the source base station to trigger the source base station to release the UE context.

[0088] 18. After receiving the UE context release message, the source base station can release the radio bearers and control plane (CP) resources related to the UE context. If the data transfer has not been completed yet, the source base station does not release the related resources and continues to perform the data transfer. After the data transfer is completed, the source base station releases the related resources.

[0089] Conditional PSCell Addition / Change (CPAC) is a process of conditional PSCell addition (CPA) and conditional PSCell change (CPC). Both CPA and CPC are the addition or change of the primary secondary cell (PSCell) in the DC scenario. The main idea is as follows. Multiple candidate PSCell cells are configured on the network, and each candidate PSCell cell configuration includes the cell configuration and execution conditions. When the execution conditions are met, the UE can autonomously perform the addition or change of the PSCell.

[0090] CPA: The CPA process is a process in which PSCell addition is executed when the conditions for PSCell addition are met. FIG. 4A is a flowchart of CPA according to an embodiment of the present application. Hereinafter, as an example, the procedure of CPA triggered by the MN in the MR-DC scenario will be used.

[0091] 1. The MN sends a secondary cell addition request to the SN where the candidate cell is located.

[0092] 2. The SN where the candidate cell is located sends a secondary cell addition request positive acknowledgment (ACK) to the MN, and the secondary cell addition request positive acknowledgment may include an RRC reconfiguration message a.

[0093] 3. The MN uses the RRC reconfiguration message (i.e., RRC reconfiguration message A) to send the CPA configuration to the UE. The RRC reconfiguration message includes the CPA configuration (i.e., one or more RRC reconfiguration messages b) and the execution conditions associated therewith. Each RRC reconfiguration message b includes one RRC reconfiguration message a from the candidate SN and optionally includes the MCG configuration.

[0094] 4. After receiving the RRC reconfiguration message of the MN, the UE returns an RRC reconfiguration complete message to the MN. The UE uses another RRC configuration other than the CPA configuration in the RRC reconfiguration message. In addition, after the UE receives the RRC reconfiguration message of the MN, the UE further executes step 4a.

[0095] 4a. The UE starts evaluating the execution conditions. When the execution conditions of the candidate cell are met, the UE uses the configuration of the selected candidate cell in the RRC reconfiguration message and sends an RRC reconfiguration complete message to the MN. The RRC reconfiguration complete message includes the RRC reconfiguration complete message of the selected candidate cell and information about the selected candidate cell.

[0096] 5. The MN transfers the RRC Reconfiguration Complete message of the selected candidate cell to the serving network (SN) where the selected candidate cell is located, in order to notify the SN that the reconfiguration process has been completed successfully. The MN can further send an SN Release Request message to another candidate SN to cancel the CPA.

[0097] 6. The UE performs a RACH process towards the selected PSCell (selected candidate cell / candidate cell that meets the execution conditions).

[0098] 7. The MN sends a sequence number state transfer to the target SN.

[0099] 8. The MN and the target SN perform data transfer.

[0100] 9 - 12. Perform a path switching process.

[0101] CPC: The CPC process is a process in which PSCell change is executed when the conditions for PSCell change are met. FIGS. 4B - 1 and 4B - 2 are flowcharts of CPC according to an embodiment of the present application. Hereinafter, the procedure of CPC triggered by the MN in the MR - DC scenario is used as an example.

[0102] 1. The MN sends a secondary cell addition request to the serving network (SN) where the candidate cell is located (including the T - SN and candidate T - SN in the figure).

[0103] 2. The SN where the candidate cell is located sends a secondary cell addition positive acknowledgment (ACK) to the MN, and the secondary cell addition positive acknowledgment may include an RRC Reconfiguration message a.

[0104] 3. The MN sends the CPC configuration to the UE using an RRC reconfiguration message (i.e., RRC reconfiguration message A). The RRC reconfiguration message includes the CPC configuration (i.e., one or more RRC reconfiguration messages b) and the execution conditions associated therewith. Each RRC reconfiguration message b includes one RRC reconfiguration message a from the candidate SNs and, optionally, includes the MCG configuration.

[0105] 4. After receiving the MN's RRC reconfiguration message, the UE returns an RRC reconfiguration complete message to the MN. The UE uses another RRC configuration other than CPC within the RRC reconfiguration message.

[0106] 4a. The MN uses the Xn-U Address Indication to notify the source SN (S-SN) that the CPC has been triggered.

[0107] 5. The UE starts evaluating the execution conditions. When the execution conditions of the candidate cell are met, the UE uses the configuration of the selected candidate cell in the RRC reconfiguration message, sends an RRC reconfiguration complete message to the MN, and the RRC reconfiguration complete message includes the RRC reconfiguration complete message of the selected candidate cell and the information regarding the selected candidate cell.

[0108] 6. The MN notifies the source SN (S-SN) to stop data transmission with the UE.

[0109] 7. The MN notifies the target SN (T-SN) (the SN where the selected candidate cell / candidate cell that meets the execution conditions is located) that the RRC reconfiguration process of the target SN has been completed, and the MN can further send an SN release request message to another candidate SN to cancel the CPC.

[0110] 8. The UE executes the RACH process towards the target SN.

[0111] 9. The source SN sends the sequence number state transfer to the target SN via the MN.

[0112] 10. The MN and the target SN execute data transfer.

[0113] 11 - 17. Execute the path switching process.

[0114] The processes of FIGS. 4A and 4B - 1 and 4B - 2 are both CPA or CPC processes triggered by the MN. In fact, the CPC may alternatively be triggered by the SN, that is, the source SN sends a secondary cell addition request to the MN. When it is determined that the secondary cell change can be executed, the MN executes step 1 and subsequent steps. Details are not described here.

[0115] Continuous CPAC: In the aforementioned CPA process and CPC process, after the RACH process between the UE and the target cell is completed, the UE releases the CPA / CPC configuration. Therefore, the UE cannot use the CPAC configuration until the network is reconfigured or the network is restarted. To reduce the SCG change delay and signaling overhead, after the SCG changes and before the network is reconfigured, the execution of CPAC (subsequent CPAC) can be continued, that is, continuous CPAC is executed. FIG. 4C is a diagram of continuous CPAC according to an embodiment of the present application. As shown in FIG. 4C, the scenario of continuous CPAC is described as follows.

[0116] 1. The UE communicates with cell 3 (C3) served by the master node MN and the SN (another SCell may exist), and cell 3 is the current PSCell of the UE.

[0117] 2. The network configures a CPC configuration for the UE, the candidate cells include cells {1, 2,..., 9}, and the CPC configuration may further include the configuration and execution conditions of each candidate cell.

[0118] 3. When the UE detects that the execution condition of cell 5 (C5) is satisfied, the UE changes the PSCell to cell 5. After completing the connection with cell 5, the UE does not release the CPC configuration, continues to maintain the CPC configuration, and executes the CPC process.

[0119] 4. The UE can continue to evaluate other candidate cells. When another candidate cell satisfies the execution condition, the UE triggers the PSCell change process. For example, in Figure 4C, the UE later detects that cell 3 satisfies the execution condition. Therefore, the UE then switches the PSCell to cell 3.

[0120] L1 / L2 Handover: The L1 / L2 (Layer 1 / Layer 2) handover is related to the RRC handover in Figure 3 and means that the handover process is completed using a MAC control element (CE) or downlink control information (DCI). The gain is to reduce the access delay. Therefore, the service interruption and signaling overhead are reduced. Figure 5A is a diagram of the L1 / L2 handover process for the DU - to - DU handover according to an embodiment of the present application. As shown in Figure 5A, the process includes, but is not limited to, the following steps.

[0121] 1. The CU distributes a measurement configuration to the UE.

[0122] 2. The UE reports a measurement report to the CU based on the measurement configuration, and the measurement report is used to assist the CU in making a handover decision and determining candidate cells.

[0123] 3. The CU sends a handover request or candidate cell addition request to a candidate DU (including the target DU).

[0124] 4. The candidate DU (including the target DU) executes handover approval control based on the handover request and sends a handover request positive response (ACK) to the CU.

[0125] 5. The CU distributes L1 / L2 pre-configuration information to the UE. The L1 / L2 handover pre-configuration information may include a plurality of candidate cells and configuration information of the plurality of candidate cells. The L1 / L2 pre-configuration information may be included in the RRC reconfiguration message. After receiving the L1 / L2 pre-configuration information, the UE continues to maintain data transmission with the source cell. The UE can perform measurements based on the network configuration, and the network makes a handover decision.

[0126] 6. The source DU distributes an L1 / L2 handover command to the UE. The L1 / L2 handover command instructs the UE to switch to the target cell served by the target DU.

[0127] 7. The UE executes the RACH process to establish a connection with the target cell. After receiving the L1 / L2 handover command, the UE stops data transmission with the source cell.

[0128] 8. After establishing a connection with the target DU, the UE performs data transmission with the target DU. The subsequent path switching process between the DU and the CU will not be described again.

[0129] Conditional L1 / L2 handover: Conditional L1 / L2 handover means that the network distributes execution conditions to candidate cells for L1 / L2 handover, and when the execution conditions are met, the UE triggers an L1 / L2 handover. Figure 5B is a diagram of the conditional L1 / L2 handover process for DU-to-DU handover according to an embodiment of the present application. As shown in Figure 5B, the process includes, but is not limited to, the following steps.

[0130] Steps 1 to 4 are exactly the same as Steps 1 to 4 in Figure 5A. Here, the details will not be described again.

[0131] 5. The CU distributes L1 / L2 handover pre-configuration information to the UE, and the L1 / L2 handover pre-configuration information may include a plurality of candidate cells, configuration information of the plurality of candidate cells, and related execution conditions. The UE triggers an L1 / L2 handover only when it evaluates that a candidate cell meets the execution conditions. The L1 / L2 pre-configuration information may be included in an RRC reconfiguration message.

[0132] 6. The UE stores the L1 / L2 pre-configuration information and starts evaluating candidate cells. In this case, the UE continues to perform data transmission with the source DU.

[0133] 7. When it detects that a candidate cell meets the execution conditions, the UE uses that candidate cell as the target cell and uses the candidate DU where the target cell is located as the target DU.

[0134] 8. The UE starts a RACH process for the target DU and establishes a connection with the target DU.

[0135] 9. After establishing a connection with the target DU, the UE performs data transmission with the target DU. The subsequent path switching process between the DU and the CU will not be described again.

[0136] In addition to the aforementioned L1 / L2 handover between DUs (including conditional L1 / L2 handover between DUs), there is further an L1 / L2 handover between DUs (including conditional L1 / L2 handover between DUs). In other words, the target cell and the source cell of the handover belong to the same DU, and the source DU and the target DU in Figures 5A and 5B are replaced by the source cell and the target cell, respectively.

[0137] Note that conditional L1 / L2 handover is a handover method of L1 / L2 handover. Therefore, in the following embodiments, implementations applicable to L1 / L2 handover are also applicable to conditional L1 / L2 handover, and vice versa. Details will not be described in the following embodiments.

[0138] Continuous L1 / L2 handover: After the L1 / L2 handover is completed once, the pre-configuration of candidate cells can be continuously remembered to support continuous L1 / L2 handover. For details, please refer to FIG. 5C. FIG. 5C is a diagram of a continuous L1 / L2 handover scenario according to an embodiment of the present application. As shown in FIG. 5C, the functions of the base station are completed by a combination of an independent CU and an independent DU. One CU can be connected to one or more DUs, and each DU establishes a connection with the UE via a cell corresponding to the DU.

[0139] 1. The UE communicates with cell 3 (C3) served by the DU, and cell 3 is the current PCell of the UE.

[0140] 2. The network distributes L1 / L2 handover pre-configuration information to the UE. The candidate cells in the pre-configuration information include cells {1, 2,..., 9}. The L1 / L2 handover pre-configuration information includes the configuration of each candidate cell, and optionally, may further include the execution conditions associated with each candidate cell.

[0141] 3. When the UE detects that the execution condition of cell 4 (C4) is satisfied, or when the UE receives a handover command from the base station instructing the UE to switch to cell 4, the UE changes the PCell to cell 4.

[0142] After accessing the target cell once, the UE does not release the L1 / L2 handover pre-configuration information and continues to maintain the L1 / L2 handover pre-configuration information.

[0143] 4a. Optionally, the UE can continue to evaluate another candidate cell. If another candidate cell meets the execution conditions, the UE triggers the PCell change process. For example, in FIG. 5C, the UE later detects that cell 3 meets the execution conditions. Therefore, the UE then switches the PCell to cell 3.

[0144] 4b. Optionally, the UE then receives a handover command from the base station instructing the UE to switch to cell 5 (C5). Therefore, the UE then switches the PCell to cell 5.

[0145] In scenarios where continuous cell handovers need to be performed, including continuous CPAC, continuous L1 / L2 handovers, and continuous conditional L1 / L2 handovers, it can be seen from the above description that the following two features are included. (1) The network may need to configure more candidate cells for the terminal device for subsequent handovers. (2) After completing a cell handover once, the UE does not release the configuration information of the relevant candidate cells and continues to maintain the configuration information for performing the next cell handover. These situations can lead to the following results. That is, the UE may be assigned or need to maintain a large number of candidate cells. In addition, as the UE moves, not all candidate cells may be appropriate for the UE when performing the cell handover process. In this case, if the UE measures or evaluates all candidate cells to determine the target cell of the handover, there are problems such as an unclear range of cells to be measured or low cell handover efficiency. In addition, additional measurement power consumption may be caused.

[0146] Based on this, FIG. 6A is a flowchart of a cell measurement method according to an embodiment of the present application. As shown in FIG. 6A, the method includes the following steps.

[0147] 101. The first network device determines first indication information, where the first indication information indicates at least one candidate cell and a first cell set corresponding to (or associated with) a first candidate cell among the at least one candidate cell, and the first cell set includes at least one cell.

[0148] The first network device in this embodiment of the present application is an interface device that provides a control plane connection to the terminal device in the cell handover process. For example, in CPAC, the first network device may be a master base station (MN). In L1 / L2 handover or conditional L1 / L2 handover, the first network device may be the central unit (CU) of the master base station. Assuming that in some possible situations, the secondary base station (SN) also has a structure with an independent CU and an independent DU, the first network device may also be the CU of the SN.

[0149] The terminal device in the embodiment of the present application may also be referred to as a terminal, user equipment (UE), mobile station (MS), mobile terminal (MT), etc. The terminal device may be a mobile phone, tablet computer (Pad), computer with a wireless transceiver function, virtual reality (VR) terminal device, augmented reality (AR) terminal device, wireless terminal for industrial control, wireless terminal for self-driving, wireless terminal for remote medical surgery, wireless terminal for smart grid, wireless terminal for transportation safety, wireless terminal for smart city, wireless terminal for smart home, etc.

[0150] First, the first network device can obtain at least one candidate cell of the terminal device. Specifically, for example, the first network device may determine the candidate cell based on one or more of a network topology, network deployment, an estimated moving direction of the terminal, or statistical information, or may determine the candidate cell of the terminal device by referring to a measurement report (including a layer 1 measurement report or a layer 3 measurement report) reported by the terminal device.

[0151] For example, at least one candidate cell is at least one candidate primary-secondary cell of a conditional primary-secondary cell addition CPA or a conditional primary-secondary cell change CPC. In other words, this embodiment of the present application can be applied to the CPA or CPC process, that is, to the scenarios corresponding to FIGS. 4A to 4C.

[0152] Furthermore, the MN can send an SN addition request to the candidate SN to determine whether the SN permits the use of the cell served by the SN as a candidate cell for addition or change. After receiving the SN addition request ACK sent by the candidate SN, the MN determines to use the determined cell served by the SN as a candidate cell for addition or change. This is shown in steps 1 and 2 of FIGS. 4A to 4C. The MN includes the determined cell served by the SN in at least one candidate cell of the first instruction information. For example, before the MN sends an SN addition request to the candidate SN, the SN can send an SN change request to the MN.

[0153] After determining a plurality of candidate cells for the addition or change of the primary-secondary cell, the MN can further determine a first cell set corresponding to a first candidate cell among the plurality of candidate cells.

[0154] For example, MN may determine a first cell set corresponding to a first candidate cell based on one or more of network topology, network deployment, an estimated moving direction of a terminal, or statistical information, or may determine a first cell set corresponding to the first candidate cell by referring to a measurement report reported by a terminal device.

[0155] In some cases, the SN addition request sent by the MN to a candidate SN (e.g., the first candidate SN) may include a candidate SN list. After receiving the SN addition request, the first candidate SN may further send a request message to another candidate SN to request to determine whether the other candidate SN agrees to include the cell of the other candidate SN in a first cell set corresponding to the cell served by the first candidate SN. If the other candidate SN agrees to include the cell of the other candidate SN in the first cell set corresponding to the cell served by the first candidate SN, the SN addition request ACK (or another message) sent by the first candidate SN to the MN may further include the first candidate SN or the first cell set associated with the candidate cell served by the first candidate SN. The MN can determine a first cell set corresponding to any first candidate cell among a plurality of candidate cells based on the first cell sets sent by a plurality of candidate SNs.

[0156] For example, at least one candidate cell is at least one candidate primary cell for an L1 / L2 handover or a conditional L1 / L2 handover. In other words, this embodiment of the present application may alternatively be applied to an L1 / L2 handover process or a conditional L1 / L2 handover process, that is, to the scenarios corresponding to FIGS. 5A to 5C.

[0157] Furthermore, the CU can send a request message to the candidate DU to determine whether the candidate DU permits the use of the cell served by the candidate DU as a candidate cell for handover. After receiving the request ACK sent by the candidate DU, the CU determines to use the determined cell served by the DU as a candidate cell for handover. This is shown in steps 3 and 4 from FIG. 5A to FIG. 5C. The CU includes the determined cell served by the DU in at least one candidate cell of the first indication information.

[0158] After determining a plurality of candidate cells for L1 / L2 handover, the CU can further determine a first cell set corresponding to a first candidate cell among the plurality of candidate cells.

[0159] For example, the CU may determine the first cell set corresponding to the first candidate cell based on one or more of network topology, network deployment, estimated moving direction of the terminal, information from the DU, or statistical information, or may determine the first cell set corresponding to the first candidate cell by referring to the measurement report reported by the terminal device.

[0160] At least one cell in the first cell set is a cell that is measured or evaluated by the terminal device when the first candidate cell is used as the serving cell (serving PSCell or serving PCell) of the terminal device. When the serving cell of the terminal device is the first candidate cell, the terminal device only needs to measure the cells in the first cell set, or the terminal device only needs to evaluate whether the cells in the first cell set meet the execution conditions. For details, please refer to Table 1 below.

[0161]

Table 1

[0162] Note that Table 1 shows only the first cell set corresponding to some of the plurality of candidate cells when several candidate cells are used as the first candidate cell. However, when several candidate cells or all candidate cells are used as the first candidate cell, it can be inferred that the first instruction information can indicate the first cell set corresponding to the several candidate cells or the all candidate cells. Table 1 is not limited to this.

[0163] For example, the first cell set includes one or more cells other than the first candidate cell among at least one candidate cell, or the cells in the first cell set belong to at least one candidate cell. As shown in Table 1, when the first candidate cell is cell 3, the first cell set corresponding to cell 3 includes cells 1, 2, 4, 5, and 8. These cells are all the cells of the candidate cells configured by the first network device for the terminal device. The cells in the first cell set associated with the first candidate cell can be candidate cells that can be detected or have good signal quality when the terminal device is located within the coverage range of the first candidate cell. When the serving cell of the terminal device is the first candidate cell, in order to reduce power overhead, the terminal device may measure or evaluate only some of the candidate cells based on the first cell set.

[0164] For example, the cells in the first cell set may include cells other than at least one candidate cell. As shown in Table 1, when the first candidate cell is Cell 4, the first cell set corresponding to Cell 4 includes Cell 3, Cell 5, and Cell 11. Cell 11 does not belong to one of the at least one candidate cells configured for the terminal device, but Cell 11 is adjacent to Cell 4. When Cell 4 is used as the serving cell of the terminal device, Cell 11 can meet the handover requirements of the terminal device. Therefore, the first network device can indicate Cell 11 as a cell in the first cell set of Cell 4. The cells in the first cell set associated with the first candidate cell can be cells that can be detected or have good signal quality when the terminal device is located within the coverage area of the first candidate cell. When the serving cell of the terminal device is the first candidate cell, in order to prevent the terminal device from losing high-quality neighboring cells and ensure the quality of the target cell to which the terminal device switches, the terminal device can measure another neighboring cell with good signal quality close to the first candidate cell based on the first cell set.

[0165] For example, the first indication information indicating the first cell set corresponding to the first candidate cell among the at least one candidate cells includes that the first indication information can indicate the first cell set by indicating the physical cell identifier (PCI) of at least one cell. For example, the network indicates the first cell set in the form of a PCI list.

[0166] Alternatively, the first indication information may indicate the first cell set by indicating the cell configuration identifier. For example, the first network device includes a configuration identifier (Config ID) in the pre-configuration information, and this configuration identifier is associated with the configuration of the candidate cell. For example, the configuration identifier may be further associated with the execution condition of the candidate cell. When the candidate cell meets the execution condition, the terminal device can perform the addition or handover of the candidate cell. The pre-configuration information may be the CPA configuration of FIG. 4A, the CPC configuration of FIGS. 4B-1 and 4B-2, or the L1 / L2 pre-configuration information of FIGS. 5A and 5B. The network can indicate the first cell set in the form of a configuration identifier list.

[0167] Alternatively, the first indication information may indicate a first cell set corresponding to the first candidate cell by using bitmapping indication information. For example, the bits corresponding to the candidate cells indicate the first cell set. In this case, the cells within the first cell set belong to a plurality of candidate cells configured by the network side for the terminal device. For details, refer to FIG. 6B. FIG. 6B is a diagram showing the correspondence between a bitmap and candidate cells according to an embodiment of the present application. As shown in FIG. 6B, the candidate cells are cells 1 to 9 (C1 to C9), each corresponding to 9 bits within the bitmap. The bitmap corresponding to cell 2 is 001110011. This means that the first cell set corresponding to cell 2 includes cells {3, 4, 5, 8, 9}. Alternatively, the bits corresponding to the maximum number of candidate cells that can be configured by the network side for the terminal device indicate the cells within the first cell set. For example, the maximum number of candidate cells that can be configured for the terminal device is 16, and those candidate cells correspond to cells 1 to 16. Assume that the first indication information for cell 3 is 1101 0011 1000 0000, and the bit indicators corresponding to cells 1, 2, 3, 7, 8, and 9 are "1". This means that these cells are the cells within the first cell set of cell 3. In the case of other cells where the bit indicator is "0", this means that these cells are not the cells within the first cell set of cell 3.

[0168] Alternatively, the first indication information may indicate the cells within the first cell set in another way. The foregoing implementations are only examples, and no specific restrictions should be imposed on the indication method of the first indication information.

[0169] Note that in step 101, the following is described. That is, the first instruction information instructs at least one candidate cell and a first cell set corresponding to a first candidate cell among the at least one candidate cells. It should be explicitly stated that the at least one candidate cell and the first cell set corresponding to the first candidate cell may be instructed by the same message using the first instruction information, or may be instructed by separate messages.

[0170] Take the CPAC scenario as an example. At least one candidate cell (candidate primary secondary cell) may be instructed by a first RRC reconfiguration message transmitted by the MN to the terminal device. When the MN transmits the first RRC reconfiguration message to the terminal device, the RRC reconfiguration message of the SN, that is, the CPAC configuration information, is included. Accordingly, the candidate primary secondary cell can be updated. Thus, at least one candidate primary secondary cell of the terminal device may instead be instructed by the CPAC configuration information, whereby the terminal device performs SN handover. In other words, the first instruction information may be transmitted by the first RRC reconfiguration message, instructing both the at least one candidate primary secondary cell and the first cell set corresponding to the first candidate cell. Alternatively, the first instruction information may be transmitted separately by the first RRC reconfiguration message and a second RRC reconfiguration message (including CPAC configuration information, and the first instruction information may be carried in the CPAC configuration information). The first RRC reconfiguration message instructs at least one candidate primary secondary cell, and the second RRC reconfiguration message instructs the first cell set corresponding to the first candidate cell.

[0171] Alternatively, an L1 / L2 handover scenario is used as an example. At least one candidate cell (candidate primary cell) may be indicated by a third RRC reconfiguration message delivered by the CU to the terminal device. Alternatively, the CU may update the candidate primary cell based on a measurement report periodically reported by the terminal device. Therefore, when delivering L1 / L2 pre-configuration information to the EU using the third RRC reconfiguration message, the CU can indicate at least one candidate primary cell corresponding to the candidate DU, whereby the terminal device performs a DU handover. In other words, the first indication information may be transmitted in the third RRC reconfiguration message, indicating both at least one candidate primary cell and a first cell set corresponding to the first candidate cell. Alternatively, the first indication information may be transmitted separately in the third RRC reconfiguration message and the fourth RRC reconfiguration message (including L1 / L2 pre-configuration information, and the first indication information may be carried in the L1 / L2 configuration information). The third RRC reconfiguration message indicates at least one candidate primary cell, and the fourth RRC reconfiguration message indicates a first cell set corresponding to the first candidate cell.

[0172] In the foregoing description, since the first instruction information transmitted with the same message instructs both at least one candidate cell and the first cell set corresponding to the first candidate cell, the candidate cell and the first cell set of the first candidate cell can be instructed at once. This helps the terminal device to ensure the consistency and completeness among multiple candidate cells and the first candidate cell. The first instruction information transmitted in separate messages separately instructs at least one candidate cell and the first cell set corresponding to the first candidate cell. In addition, usually, at least one candidate cell is instructed first, and then the first cell set corresponding to the first candidate cell is instructed. In this way, the delay when the terminal device obtains at least one candidate cell can be reduced, so the terminal device executes other processes (including candidate cell measurement, etc.) based on the obtained at least one candidate cell. The first network device can instruct the first candidate cell and the cell set in real time based on the updated position of the terminal device. Thereby, the accuracy and real-time performance of information instruction are improved, the transmission of unnecessary instruction content is avoided, and the communication overhead is reduced.

[0173] 102. The first network device transmits the first instruction information. For example, the first instruction information may be included in the pre-configuration information, and this pre-configuration information may be the CPA configuration in FIG. 4A, the CPC configuration in FIGS. 4B-1 and 4B-2, or the L1 / L2 pre-configuration information in FIGS. 5A and 5B. In other words, the first network device may transmit the first instruction information using step 3 from FIG. 4A to FIG. 4C or step 5 from FIG. 5A to FIG. 5C.

[0174] 103. The terminal device receives the first instruction information, the terminal device measures or evaluates the cells in the first cell set based on the first instruction information, and the serving cell of the terminal device is the first candidate cell. In other words, the first instruction information instructs the cells to be measured (or evaluated) by the terminal device when the serving cell of the terminal device is the first candidate cell.

[0175] After determining the first instruction information, the first network device sends the first instruction information to the terminal device. The terminal device receives the first instruction information and executes a cell measurement or evaluation process based on the first instruction information. For example, the terminal device executing cell measurement based on the first instruction information may correspond to step 5 in FIG. 5A. As another example, the terminal device executing cell evaluation based on the first instruction information may correspond to step 4a in FIG. 4A, step 5 in FIG. 4B-1, or step 6 in FIG. 5B.

[0176] For example, in the CPC scenario, the first candidate cell is the serving cell of the terminal device. This means that the first candidate cell is the primary / secondary serving cell of the terminal device. When the serving cell is the first candidate cell, the terminal device evaluates whether the cells in the first cell set meet the execution conditions based on the first instruction information. The execution conditions may be included in the message in which the first instruction information is placed. The terminal device receives the first instruction information shown in Table 1. When the primary / secondary serving cell of the terminal device is cell 5, the terminal device measures and evaluates the cells {3, 4, 6, 9} in the first cell set to determine whether there is a cell that meets the execution conditions among these cells. If there is a cell that meets the execution conditions among these cells, the primary / secondary serving cell is switched, or the SN is switched.

[0177] For example, in an L1 / L2 handover scenario, the first candidate cell is the serving cell of the terminal device. This means that the first candidate cell is the primary serving cell of the terminal device (or in some cases, it can be the primary secondary serving cell of the terminal device). When the serving cell is the first candidate cell, the terminal device measures the cells within the first cell set based on the first indication information. Alternatively, when the serving cell is the first candidate cell, the terminal device evaluates whether the cells within the first cell set meet the execution conditions based on the first indication information. The terminal device receives the first indication information shown in Table 1. If the primary serving cell (or primary secondary serving cell) of the terminal device is cell 5, the terminal device measures or evaluates the cells among the cells {3, 4, 6, 9} within the first cell set. When the terminal device evaluates the cells within the first cell set, the terminal device determines whether there is a cell that meets the execution conditions among these cells. If there is a cell that meets the execution conditions among these cells, the primary serving cell (or primary secondary serving cell) is switched.

[0178] It should be noted that the fact that the terminal device measures or evaluates the cells within the first cell set does not mean that the terminal device can surely detect all the cells within the first cell set, and the terminal device only attempts to measure the cells within the first cell set. For example, when the serving cell of the terminal device is the first candidate cell, there is no need to measure or evaluate another cell outside the first cell set.

[0179] In this embodiment of the present application, it can be seen that a first network device obtains first indication information, and the first indication information indicates at least one candidate cell and a first cell set corresponding to a first candidate cell among the at least one candidate cell. The terminal device receives the first indication information and performs cell measurement based on the first cell set indicated by the first indication information. In this process, a first cell set corresponding to each first candidate cell is determined. Assuming that the cells in the first cell set are part of the candidate cells, when the terminal device performs a cell handover, the cells that need to be measured or evaluated can be reduced, and as a result, the handover efficiency is improved and the power of the terminal device is reduced. In addition, assuming that the cells in the first cell set include cells other than the candidate cells, the cells measured and evaluated by the terminal device cannot be limited to at least one candidate cell configured for the terminal device. Thereby, the success rate of the cell handover of the terminal device is improved. In short, in this embodiment of the present application, since the cells measured and evaluated by the terminal device are associated with the serving cell, the range of the cells measured and evaluated changes with the serving cell. Thereby, the efficiency of cell measurement and evaluation is improved, and the efficiency of the cell handover process is further improved.

[0180] The foregoing embodiment has been used to illustrate a situation where when the terminal device moves, the candidate cells that need to be measured and evaluated by the terminal device may change accordingly. However, in some other situations, as the position of the terminal device moves, the related configuration executed by the network side for the terminal device may become invalid. Specifically, refer to FIG. 7A. FIG. 7A is a flowchart of a communication method according to an embodiment of the present application. As shown in FIG. 7A, the method includes the following steps.

[0181] 201. The first network device determines the configuration information of the candidate cells.

[0182] Similar to the foregoing embodiments, the first network device is an interface device that provides a control plane connection to the terminal device in cell handover communication. For example, in CPAC, the first network device may be the MN. In L1 / L2 handover or conditional L1 / L2 handover, the first network device may be the CU of the master base station. In some possible situations, the first network device may alternatively be the CU of the SN.

[0183] The first network device can determine the configuration information of the candidate cell, such as the identifier of the candidate cell, the access conditions of the candidate cell, and the measurement configuration corresponding to the candidate cell. The first network device can determine the configuration information of the candidate cell based on network topology, network deployment, and cell parameters, such as information on the frequency band where the cell is located.

[0184] 202. The first network device transmits a first message to the terminal device, and the first message includes the configuration information of the candidate cell.

[0185] After determining the configuration information of the candidate cell, the first network device uses the first message to transmit the configuration information of the candidate cell to the terminal device, whereby the terminal device measures or evaluates the candidate cell. The configuration information of the candidate cell may specifically be included in the CPA configuration of FIG. 4A, the CPC configuration of FIGS. 4B-1 and 4B-2, or the L1 / L2 pre-configuration information of FIGS. 5A and 5B.

[0186] When the terminal device receives a first message and the first condition is satisfied, the terminal device sends a second message to the first network device, and the second message is used to request updating the configuration information of the candidate cell. The first condition is a condition that the signal quality of the serving cell or the candidate cell needs to satisfy. For example, the first condition may specifically include at least one of the following, that is, the signal quality of the serving cell is less than or equal to a first threshold, the number of detectable candidate cells is less than or equal to a first number, or the signal quality of the candidate cell is less than or equal to a second threshold.

[0187] In some cases, for the position change caused by the movement of the terminal device, refer to FIG. 7B for details. FIG. 7B is a diagram of the position movement of the terminal device according to an embodiment of the present application. As shown in FIG. 7B, when the terminal device is at position 1, the first network device distributes the configuration information of the candidate cell to the terminal device based on the current serving cell C3 of the terminal device, and the candidate cells include C{1, 2, 4, …, 8}. Even when the terminal device moves to position 2, the configuration information of the candidate cell is still applicable. However, when the terminal device moves to position 3, some candidate cells at a long distance, for example, cells {2, 5, 7}, are no longer cells that can be measured by the terminal device, and these cells are no longer used as candidate cells of the terminal device. Correspondingly, the terminal device can have a new candidate cell, for example, cell 9. In this case, the configuration information of the candidate cell previously received by the terminal device becomes inapplicable. However, the first network device may not be able to update the configuration information of the candidate cell in a timely manner. As a result, the terminal device may not be able to perform a cell handover, or the communication quality may deteriorate.

[0188] Based on this, the terminal device can trigger the transmission of a second message to the first network device to request updating the configuration information of the candidate cell or to request updating the candidate cell. The specific trigger condition includes the first condition, and the first condition may specifically include one or more of the following.

[0189] (1) The signal quality of the serving cell is below a first threshold. For example, in FIG. 7B, when the serving cell of the terminal device is C3, the configuration information of the candidate cell is received. When the terminal device moves to position 3, the signal quality of the serving cell C3 deteriorates. When the signal quality of the serving cell C3 is below the first threshold, the terminal device may be triggered to send a second message to the first network device. The signal quality of the cell can be represented by parameters such as Reference Signal Receiving Power (RSRP), Received Signal Strength Indication (RSSI), and Reference Signal Receiving Quality (RSRQ). The first threshold is, for example, a threshold of RSRP, specifically, -110 dBm (decibel-milliwatt). The first threshold is configured by the network or set in advance. For example, the first threshold is included in the first message.

[0190] (2) The number of candidate cells that can be detected by the terminal device is less than or equal to a first number. For example, in FIG. 7B, since the configuration information of the candidate cell is distributed by the first network device based on the current serving cell C3, the terminal device can detect a large number of candidate cells at position 1. However, when the terminal device moves to position 2 and further to position 3, the terminal device moves away from the signal coverage range of the candidate cell, so the number of candidate cells that can be detected by the terminal device decreases. Therefore, when the number of candidate cells that can be detected by the terminal device is less than or equal to the first number, the terminal device may be triggered to send a second message to the first network device. The first number is configured by the network or set in advance. For example, the first number is included in the first message.

[0191] (3) The signal quality of the candidate cells is below a second threshold. This may mean that the signal quality of all candidate cells configured by the first network device for the terminal device is below the second threshold, or it may mean that the signal quality of a third number of candidate cells among the candidate cells is below the second threshold. The second threshold and the third number may be configured by the network or may be preset. For example, the second threshold and / or the third number are included in the first message. In this case, this means that the quality of all candidate cells or a large number of candidate cells is poor and the terminal device cannot perform an effective cell handover. In this case, the terminal device may be triggered to send a second message to the first network device.

[0192] The above three conditions may be used separately or in combination to trigger the terminal device to send a second message. For example, when the signal quality of the serving cell is below the first threshold and the number of candidate cells that can be detected by the terminal device is below the first number, the terminal device is triggered to send a second message.

[0193] Optionally, the second message may include identifiers of candidate cells that the terminal device proposes to delete or add. Alternatively, the second message may include the signal quality of some candidate cells.

[0194] For example, the configuration information of the candidate cells is conditional primary secondary cell addition CPA or conditional primary secondary cell change CPC configuration information, and the second message is used to update the CPA or CPC configuration information. For example, the second message is used to request the network to add or reduce candidate cells.

[0195] In other words, this embodiment of the present application can be applied to the CPA or CPC process shown in FIGS. 4A to 4C. The first network device uses CPAC configuration information (i.e., CPA configuration information or CPC configuration information) to send the configuration information of the candidate primary / secondary cells to the terminal device. After receiving the configuration information, the terminal device performs corresponding cell measurements and evaluations to execute the primary / secondary cell handover. When one or more of the above three conditions are met, the terminal device is triggered to send a second message to the first network device to update the CPAC configuration information. After receiving the second message, the first network device can re-determine the CPAC configuration information. For example, it can re-determine the new CPAC configuration information based on information such as the second message, network topology, network deployment, the current location information of the terminal device, and whether the cells of the SN re-reported by the SN can be used as candidate cells.

[0196] For example, the configuration information of the candidate cell is the configuration information of the candidate cell for the layer 1 / layer 2 handover, and the first message is used to request to update the layer 1 / layer 2 handover configuration information. For example, the first message is used to request the network to add or reduce candidate cells.

[0197] In other words, this embodiment of the present application can be applied to the L1 / L2 handover process shown in FIGS. 5A to 5C. The first network device uses the L1 / L2 pre-configuration information to send the configuration information of the candidate primary cell (or candidate primary secondary cell) to the terminal device. After receiving the configuration information, the terminal device performs corresponding cell measurements or evaluations to execute cell handover. When one or more of the above three conditions are met, the terminal device is triggered to send a second message to the first network device to update the L1 / L2 pre-configuration information. After receiving the second message, the first network device can re-determine the L1 / L2 configuration information. For example, it can re-determine the new L1 / L2 configuration information based on information such as the second message, network topology, network deployment, current location information of the terminal device, and measurement reports reported by the terminal device.

[0198] Before receiving the updated configuration information of the candidate cell distributed by the network, the terminal device continues to use or maintain the original configuration information of the candidate cell.

[0199] In this embodiment of the present application, it can be seen that when the first condition is met to require updating the configuration information of the candidate cell, the terminal device can be triggered to send a second message to the first network device. In this way, since the terminal device actively requests the network device to update the configuration information of the candidate cell, the terminal device can timely obtain the most accurate configuration information of the candidate cell to execute cell handover. As a result, the probability of successful cell handover is increased, and the delay of cell handover caused by the inability to timely obtain the effective configuration information of the candidate cell is reduced.

[0200] It should be noted that this embodiment of the present application may be implemented separately or in combination with the foregoing embodiments corresponding to FIGS. 6A and 6B. In other words, both the first instruction information and the configuration information of the candidate cell are transmitted to the terminal device, and the terminal device performs measurements or evaluations based on the first instruction information. When the first condition is satisfied, the terminal device transmits a second message to request to update the configuration information of the candidate cell and to request to update the content of the first instruction information. At least one candidate cell corresponding to the terminal device and a first cell set corresponding to the first candidate cell among the at least one candidate cell are correspondingly updated as the configuration information of the candidate cell is updated. In this way, when timely obtaining the configuration information of the candidate cell corresponding to the current position, the terminal device can also obtain the first cell set corresponding to the candidate cell. In this way, the terminal device can perform more accurate and rapid cell measurements and evaluations, and further improve the cell handover success rate.

[0201] In some cases, as the position of the terminal device moves, the related configuration executed by the network side for the terminal device becomes invalid. In addition to requesting an update of the configuration information of the candidate cell described in the embodiments corresponding to FIGS. 7A and 7B, the terminal device can further actively transmit a measurement report to the network device. Specifically, please refer to FIG. 8. FIG. 8 is a flowchart of a communication method according to an embodiment of the present application. As shown in FIG. 8, the method includes the following steps.

[0202] 301. The first network device determines the configuration information of the candidate cell.

[0203] 302. The first network device transmits a first message, and the first message includes the configuration information of the candidate cell.

[0204] For details of the descriptions of steps 301 and 302, please refer to the descriptions of steps 201 and 202. Details will not be described again here.

[0205] When the terminal device receives a first message and a second condition is satisfied, it triggers the transmission of a measurement report to a first network device, and the measurement report includes the signal quality of candidate cells. The second condition is a condition that the signal quality of the serving cell or candidate cells needs to satisfy. For example, the second condition includes at least one of the following: namely, the signal quality of the serving cell is below a second threshold, the number of candidate cells that can be detected by the terminal device is below a second number, the signal quality of the candidate cells is below a third threshold, the serving cell is switched to a first cell, where the first cell is a cell within a second cell set, the switching, or the signal quality of one or more cells other than the candidate cells is above a fourth threshold.

[0206] Similarly, assuming that the position of the terminal device changes as described in the embodiments of FIGS. 7A and 7B, the configuration information of the candidate cells transmitted by the first network device may become inapplicable. In this case, the terminal device can transmit a measurement report to the first network device. The measurement report includes the signal quality of some or all of the candidate cells and may further include the signal quality of cells other than the candidate cells. In this case, the first network device can update the configuration information of the candidate cells based on the measurement report. Specifically speaking, for example, the execution conditions of the candidate cells are updated, or the candidate cells are updated.

[0207] The second condition for triggering the terminal device to transmit a measurement report may include one or more of the following.

[0208] (1) The signal quality of the serving cell is below a second threshold.

[0209] (2) The number of candidate cells that can be detected is below a second number.

[0210] (3) The signal quality of the candidate cells is below a third threshold.

[0211] For a specific description of conditions (1) to (3), refer to the related descriptions of the embodiments in FIGS. 7A and 7B. The difference is that conditions (1) to (3) in FIGS. 7A and 7B are only used to trigger the terminal device to send a second message to the first network device. Conditions (1) to (3) in this embodiment of the present application are used to trigger the terminal device to send a measurement report to the first network device.

[0212] (4) The serving cell is switched to a first cell, and the first cell is a cell within a second cell set. In other words, the terminal device switches to a first cell within a predetermined second cell set. The cells within the second cell set are candidate cells. For example, the cells within the second cell set are C{8,9} in FIG. 7B. For example, when the network instructs the terminal device to switch to a cell other than the candidate cell, the cells within the second cell set may alternatively be cells other than the candidate cells. The serving cell is switched to the first cell. This may indicate that the terminal device has moved to a location where the signal quality of the candidate cell is poor, and the terminal device may be triggered to send a measurement report to the first network device. As a result, criteria for making a decision, for example, criteria for deciding whether to update the configuration information of the candidate cell and how to update the configuration information of the candidate cell, are provided to the first network device. The first cell or the second cell set may be configured by the network and may be included in, for example, a first message.

[0213] (5) The signal quality of one or more cells other than the candidate cells is equal to or higher than a fourth threshold. The terminal device knows, through measurement, that the signal quality of one cell other than the candidate cells, or the signal quality of a fourth number of cells, is equal to or higher than the fourth threshold. The fourth number and the fourth threshold may be configured by the network or may be preset, and may be included in the first message, for example. In this case, the terminal device can trigger the transmission of a measurement report to the first network device, and the terminal device determines whether to update the configuration information of the candidate cells. Updating the configuration information of the candidate cells includes adding one or more cells as candidate cells of the terminal device, etc.

[0214] Conditions (1) to (5) may be used separately or in combination to trigger the terminal device to send a measurement report to the first network device. For example, when conditions (1), (3), and (5) are all satisfied, it means that the signal quality of the current serving cell of the terminal device is poor, the signal quality of all candidate cells is poor, but the signal quality of another cell is good. In this case, the terminal device may be triggered to send a measurement report to the first network device. The measurement report is used by the first network device as a criterion for determining whether to update the configuration information of the candidate cells and how to update the configuration information of the candidate cells.

[0215] In this embodiment of the present application, it can be seen that when the second condition is satisfied, the terminal device may be triggered to send a measurement report to the first network device. The measurement report is used by the first network device as a criterion for how to update the configuration information of the candidate cells. In this way, since the terminal device actively sends a measurement report to the network device, the network device can more quickly and accurately determine a solution to update the configuration information of the candidate cells. Furthermore, the success rate of the cell handover process is increased.

[0216] Note that this embodiment of the present application may be implemented separately or in combination with the embodiments described in FIGS. 7A and 7B. Specifically, after receiving the configuration information of the candidate cell, assuming that the terminal device determines that it satisfies one or more of conditions (1) to (3) in FIGS. 7A and 7B and also satisfies one or more of conditions (1) to (5) in this embodiment of the present application (conditions (1) to (3) in FIGS. 7A and 7B and conditions (1) to (3) in this embodiment of the present application may be conditions corresponding to the same threshold or the same number, or conditions corresponding to different thresholds or different numbers), the terminal device is triggered to send a second message and a measurement report to the first network device to request updating the configuration information of the candidate cell. In addition, since the terminal device can send a measurement report to the network device, the network device determines how to specifically update the configuration information of the candidate cell based on the measurement report.

[0217] It can be seen that by combining the embodiments corresponding to FIGS. 7A and 7B with the embodiments corresponding to FIG. 8, the efficiency and accuracy of updating the configuration information of the candidate cell by the network device can be further improved, and the efficiency and success rate of performing cell handover by the terminal device based on the new configuration information of the candidate cell can be further improved.

[0218] Similarly, the embodiment corresponding to FIG. 8 may be combined with the embodiments corresponding to FIGS. 6A and 6B. The specific combination method may be as follows. That is, the terminal device is triggered to send a measurement report to the first network device, and the first network device determines the first instruction information based on the measurement report. Alternatively, the embodiments corresponding to FIGS. 6A and 6B, the embodiments corresponding to FIGS. 7A and 7B, and the embodiments corresponding to FIG. 8 may be combined. The specific combination method has been described above. Details will not be described again here.

[0219] In some cases, regarding the configuration information of the received candidate cell (for details of the process by which the terminal device obtains the configuration information of the candidate cell, refer to steps 201 and 202 of the foregoing embodiment), in addition to enabling or storing the configuration information of the candidate cell, the terminal device can invalidate or release the configuration information of the candidate cell. For details, refer to FIG. 9. FIG. 9 is a flowchart of a communication method according to an embodiment of the present application. This method includes the following steps.

[0220] 401. The first network device sends a third message to the terminal device, and the third message instructs the terminal device to switch to a target cell, and the target cell does not belong to the candidate cell. The third message is, for example, an RRC reconfiguration message or a handover command.

[0221] 402A. The terminal device receives the third message sent by the first network device, and the terminal device switches to the target cell instructed by the third message, and considers that the configuration information of the candidate cell is valid or stored.

[0222] 402B. The terminal device switches to the target cell instructed by the third message, and determines whether the configuration information of the candidate cell is valid or invalid based on the instruction information A from the first network device.

[0223] Steps 402A and 402B are optional steps.

[0224] For example, the instruction information A may be included in the third message.

[0225] For example, before step 401, step 400 is further included, that is, the first network device sends the instruction information A to the terminal device.

[0226] The meanings of the first network device and the terminal device in this embodiment of the present application are the same as those in the foregoing embodiments. Details are not described again here. In some cases, the terminal device may receive instruction information transmitted by the first network device to instruct the terminal device to switch from the current serving cell (source cell) to the target cell. For example, in CPAC, the serving cell may be a PSCell. In L1 / L2 handover, the serving cell may be a PCell. When the cell detects that it meets the handover condition, the first network device can use the cell as the target cell and use the third message to instruct the terminal device of the target cell.

[0227] When the target cell belongs to the candidate cell and the first network device transmits the configuration information of the candidate cell to the terminal device. In this case, the terminal device can complete the access to the target cell based on the configuration information of the candidate cell. In this case, the configuration information of the candidate cell previously received by the terminal device is considered to be still valid. Therefore, the configuration information may be stored, maintained, etc.

[0228] If the target cell does not belong to the candidate cell, in this case, the terminal device cannot access the target cell based on the previously received configuration information of the candidate cell, and can complete the access based on the configuration information newly transmitted by the first network device. For example, the handover can be completed using the configuration in the third message. If the target cell does not belong to the candidate cell, it means that the position of the terminal device can move, or the signal of the cell can change, etc., and the previous configuration information of the candidate cell becomes inapplicable to the cell handover of the terminal device. The operations that can be performed by the terminal device in this case include the following. (1) Consider that the configuration information of the candidate cell is valid or stored. In this case, the terminal device considers that the current configuration information of the candidate cell does not adapt to the target cell, but after the position of the terminal device continues to move, or after the candidate cell parameters continue to change, the configuration information of the candidate cell, which is rejudged, can be considered to adapt to the target cell. Therefore, the configuration information of the candidate cell continues to be considered valid or stored. In this way, the probability of the first network device resending the same configuration information of the candidate cell to the terminal device can be reduced, so the signaling overhead is reduced and the delay is reduced. (2) Based on the instruction information from the first network device, determine whether the configuration information of the candidate cell is valid or invalid. For example, the first instruction information is included in the third message or the message in which the configuration of the candidate cell is placed. The network device (for example, CU) can determine whether the terminal device can still use the configuration information of the candidate cell after the handover based on the target cell, network topology, etc. The first network device can explicitly indicate whether the previously transmitted configuration information of the candidate cell is valid by using the instruction information. In this case, the terminal device can determine whether the configuration information of the candidate cell is valid or invalid based on the instruction information of the first network device, and further store the valid configuration information of the candidate cell and release the invalid configuration information of the candidate cell.

[0229] In this embodiment of the present application, when specific conditions are met, specifically, for example, when the target cell indicated by the network device is a cell other than the candidate cell, it can be seen that the configuration information of the candidate cell can be determined to be valid as compared with the general consideration of releasing the configuration information of the candidate cell received after the terminal device performs a cell handover. In this way, the signaling overhead of the configuration information of the candidate cell is reduced, and the delay of receiving the reconfiguration is reduced. Alternatively, the terminal device can determine whether the configuration information of the candidate cell is valid or invalid based on the instruction information transmitted by the network device. In this way, the configuration information of the candidate cell is processed more flexibly. Thereby, excessive communication or excessive data storage is avoided, the signaling overhead is reduced, and the delay is reduced.

[0230] Optionally, one embodiment is further included regarding whether the configuration information of the candidate cell is valid or invalid. For details, refer to FIG. 10. FIG. 10 is a flowchart of another communication method according to an embodiment of the present application. As shown in FIG. 10, the method includes the following steps.

[0231] 501. The first network device transmits the configuration information of the candidate cell to the terminal device.

[0232] 502. The terminal device triggers a radio resource control (RRC) re-establishment process, and the cell selected in the RRC re-establishment process belongs to the first network device.

[0233] For example, when the terminal device detects that a radio link failure (RLF) has occurred in the connection with the MN, the terminal device triggers the RRC re-establishment process. Specifically, the terminal device performs cell selection and attempts to resume the connection with the selected cell.

[0234] For example, the cell selected in the RRC reestablishment process can be the original serving cell (including the PCell or PSCell), or another cell belonging to the first network device. The first network device is the base station or CU where the original serving cell is located.

[0235] For example, in the RRC reestablishment process, instead, a cell not belonging to the first network device may be selected. In the RRC reestablishment process, the terminal device selects a cell based on the signal quality of the cell. Therefore, the selected cell may not belong to the first network device.

[0236] 503. The terminal device considers that the configuration information of the candidate cell is valid or stored.

[0237] When the cell selected in the RRC reestablishment process is the original serving cell (including the PCell or PSCell), or another cell belonging to the first network device, the terminal device considers that the configuration information of the candidate cell is valid or stored. In this case, since the terminal device attempts to resume the connection with the first network device, it is highly likely that the previously received configuration information of the candidate cell can still be used, and the terminal device can consider that the previously received configuration information of the candidate cell is valid or stored. The configuration information of the candidate cell includes the CPAC configuration in the CPAC process, the L1 / L2 pre-configuration information in the L1 / L2 handover process, etc. For example, the configuration information of the candidate cell may be the CPA configuration in FIG. 4A, the CPC configuration in FIGS. 4B-1 and 4B-2, or the L1 / L2 pre-configuration information in FIGS. 5A and 5B. In this process, the communication overhead caused by retransmitting the same configuration information of the candidate cell can be reduced, and the reconfiguration delay can be reduced.

[0238] Correspondingly, if the cell selected in the RRC reestablishment process does not belong to the first network device, the terminal device considers that the configuration information of the candidate cell is invalid or has been released. In this case, the configuration information of the candidate cell previously received by the terminal device may no longer be applicable to the current cell handover process. Since the terminal device releases or discards the configuration information of the candidate cell or considers the configuration information of the candidate cell to be invalid, the overhead of storing or maintaining the inapplicable configuration information of the candidate cell by the terminal device can be reduced, and the terminal device is prevented from using inappropriate configuration information.

[0239] The embodiments corresponding to FIGS. 9 and 10 may be combined with any one or more of the foregoing embodiments, and two embodiments may be combined with each other. The specific combination method is the same as the combination method in the foregoing embodiments. Details are not described again here.

[0240] As shown in FIG. 11, the communication device 600 includes a transceiver module 601 and a processing module 602. The communication device 600 may be configured to implement the functions of a terminal device or a network device in the method embodiments shown in FIGS. 6A, 7A, 8, 9, and 10.

[0241] When the communication device 600 is configured to implement the functions of a terminal device in the method embodiment shown in FIG. 6A,

[0242] The transceiver module 601 is configured to receive first indication information, where the first indication information indicates at least one candidate cell and a first cell set corresponding to a first candidate cell among the at least one candidate cell, and the first cell set includes at least one cell. The processing module 602 is used by the terminal device to measure the cells in the first cell set based on the first indication information, and the serving cell of the terminal device is the first candidate cell.

[0243] When the communication device 600 is configured to implement the functions of the first network device in the embodiment of the method shown in FIG. 7A,

[0244] The processing module 602 is configured to determine first indication information, where the first indication information indicates at least one candidate cell and a first cell set corresponding to a first candidate cell among the at least one candidate cell, and the first cell set includes at least one cell. The transceiver module 601 is configured to transmit the first indication information.

[0245] When the communication device 600 is configured to implement the functions of the terminal device in the embodiment of the method shown in FIG. 7A,

[0246] The transceiver module 601 is configured to receive a first message, where the first message includes configuration information of candidate cells.

[0247] When the processing module 602 determines that the first condition is satisfied, it triggers the transceiver module 601 to send a second message to the first network device. The second message is used to request to update the configuration information of the candidate cells. The first condition includes at least one of the following: the signal quality of the serving cell is less than or equal to a first threshold, the number of detectable candidate cells is less than or equal to a first number, or the signal quality of the candidate cells is less than or equal to a second threshold.

[0248] When the communication device 600 is configured to implement the functions of the first network device in the embodiment of the method shown in FIG. 7A,

[0249] The processing module 602 is configured to determine the configuration information of the candidate cells.

[0250] The transceiver module 601 is configured to transmit a first message, where the first message includes configuration information of a candidate cell. The receiving module is configured to receive the first message or a measurement report, where the first message is used to request updating the configuration information of the candidate cell, and the measurement report includes the signal quality of the candidate cell.

[0251] When the communication device 600 is configured to implement the functions of the terminal device in the embodiment of the method shown in FIG. 8,

[0252] The transceiver module 601 is configured to receive a first message, where the first message includes configuration information of a candidate cell.

[0253] When the processing module 602 determines that a second condition is satisfied, the processing module 602 triggers the transceiver module 601 to transmit a measurement report to a first network device, where the measurement report includes the signal quality of the candidate cell, and the second condition includes at least one of the following: the signal quality of the serving cell is less than or equal to a second threshold; the number of detectable candidate cells is less than or equal to a second number; the signal quality of the candidate cell is less than or equal to a third threshold; the serving cell is switched to a first cell, where the first cell is a cell within a first cell set; or the signal quality of one or more cells other than the candidate cell is greater than or equal to a fourth threshold.

[0254] When the communication device 600 is configured to implement the functions of the first network device in the embodiment of the method shown in FIG. 8,

[0255] The processing module 602 is configured to determine the configuration information of the candidate cell.

[0256] The transceiver module 601 is configured to transmit a first message, where the first message includes configuration information of a candidate cell, and to receive the first message or a measurement report, where the first message is used to request updating the configuration information of the candidate cell, and the measurement report is configured to include the signal quality of the candidate cell.

[0257] When the communication device 600 is configured to implement the functions of the terminal device in the embodiment of the method shown in FIG. 9,

[0258] The transceiver module 601 is configured to receive a third message transmitted by a first network device.

[0259] The processing module 602 is configured to determine the configuration information of the candidate cell, switch to the target cell indicated by the third message, and consider the configuration information of the candidate cell to be valid or stored, or switch to the target cell indicated by the third message and determine whether the configuration information of the candidate cell is valid or invalid based on the indication information A from the first network device.

[0260] When the communication device 600 is configured to implement the functions of the first network device in the embodiment of the method shown in FIG. 9,

[0261] The processing module 602 is configured to determine the third message, where the third message instructs the terminal device to switch to the target cell, and the target cell does not belong to the candidate cell.

[0262] The transceiver module 601 is configured to transmit the third message.

[0263] When the communication device 600 is configured to implement the functions of the terminal device in the embodiment of the method shown in FIG. 10,

[0264] The transceiver module 601 is configured to receive the configuration information of the candidate cell.

[0265] The processing module 602 is configured to trigger a radio resource control (RRC) reestablishment process and to consider that the cell selected in the RRC reestablishment process belongs to the first network device and that the configuration information of the candidate cell is valid or stored.

[0266] When the communication device 600 is configured to implement the functions of the network device in the embodiment of the method shown in FIG. 10,

[0267] The processing module 602 is configured to determine the configuration information of the candidate cell.

[0268] The transceiver module 601 is configured to transmit the configuration information of the candidate cell to the terminal device.

[0269] For a more detailed description of the transceiver module 601 and the processing module 602, reference may be made to the relevant description of the embodiment of the foregoing method. Details will not be described again here.

[0270] FIG. 12 is a diagram of the hardware structure of a communication device according to an embodiment of the present application. For the structure of the device in FIG. 11, reference may be made to the structure shown in FIG. 12. The communication device 1000 includes a processor 111 and a transceiver 112. The processor 111 and the transceiver 112 are electrically connected.

[0271] The processor 111 is configured to execute some or all of the computer program instructions in the memory. When some or all of the computer program instructions are executed, the device can execute the method according to any one of the foregoing embodiments.

[0272] The transceiver 112 is configured to communicate with another device, for example, to receive a message from a first network element. This message includes an identifier of a multicast and / or broadcast service, a key of the multicast and / or broadcast service, and / or a key identifier of the multicast and / or broadcast service.

[0273] Optionally, the apparatus further includes a memory 113 configured to store computer program instructions. Optionally, the memory 113 (memory #1) is disposed inside the apparatus, the memory 113 (memory #2) is integrated with the processor 111, or the memory 113 (memory #3) is disposed outside the apparatus.

[0274] It should be understood that the communication device 1000 shown in FIG. 12 may be a chip or a circuit. For example, the communication device 1000 may be a terminal device or a chip or circuit disposed in a communication device. The transceiver 112 may alternatively be a communication interface. The transceiver includes a receiver and a transmitter. Further, the communication device 1000 may further include a bus system.

[0275] The processor 111, the memory 113, and the transceiver 112 are connected using a bus system. The processor 111 is configured to control the transceiver to receive and transmit signals and to execute instructions stored in the memory 113 to complete the steps of the first device or the second device in the implementation method of the present application. The memory 113 may be integrated with the processor 111 or may be disposed separately from the processor 111.

[0276] In one implementation, the functions of the transceiver 112 may be implemented by a transceiver circuit or a dedicated transceiver chip. The processor 111 may be implemented by a dedicated processing chip, a processing circuit, a processor, or a general-purpose chip. The processor may be a central processing unit (CPU), a network processor (NP), or a combination of a CPU and an NP. The processor may further include a hardware chip or another general-purpose processor. The hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The PLD may be a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), a generic array logic (GAL), and another programmable logic device, discrete gates or transistor logic devices, discrete hardware components, etc., or any combination thereof. The general-purpose processor may be a microprocessor, or the processor may be any conventional processor, etc.

[0277] It should be further understood that the memory referred to in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include a volatile memory and a non-volatile memory. The non-volatile memory may be a read-only memory (ROM), a programmable ROM (PROM), an erasable PROM (EPROM), an electrically erasable PROM (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM) used as an external cache. By way of example and not limitation, many forms of RAM may be used, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), Synchlink DRAM (SLDRAM), and direct rambus RAM (DR RAM). It should be noted that the memory described in the present application is intended to include these memories and any other suitable types of memory, but is not limited thereto.

[0278] One embodiment of the present application provides a computer storage medium storing a computer program. This computer program includes a method applicable to the terminal device of the foregoing embodiment.

[0279] One embodiment of the present application provides a computer storage medium storing a computer program. This computer program includes a method applicable to the first network device of the foregoing embodiment.

[0280] One embodiment of the present application provides a computer program product including instructions. When this computer program product is executed on a computer, the computer can execute the method applicable to the terminal device of the foregoing embodiment.

[0281] One embodiment of the present application provides a computer program product including instructions. When this computer program product is executed on a computer, the computer can execute the method applicable to the first network device of the foregoing embodiment.

[0282] It should be understood that the serial numbers of the foregoing processes do not mean the execution order in various embodiments of the present application. The execution order of the process should be determined based on the functions and internal logics of the process, and should not constitute any limitation to the implementation process of the embodiments of the present application.

[0283] Those skilled in the art can notice that, in combination with the examples described in the embodiments disclosed in this specification, the units and algorithm steps can be implemented by electronic hardware, or by a combination of computer software and electronic hardware. Whether the function is executed by hardware or by software depends on the specific use of the technical solution and the design constraints. Those skilled in the art can implement the described functions using various methods for each specific use, but the implementation should not be considered to exceed the scope of the present application.

[0284] For the purpose of a brief description, those skilled in the art should clearly understand that the detailed working processes of the aforementioned systems, devices, and units should refer to the corresponding processes of the embodiments of the aforementioned method. Details will not be described again here.

[0285] In some embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods may be implemented in other ways. For example, the described device embodiments are only examples. For example, the division into units is only a logical function division, and it may be a different division during actual implementation. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. In addition, the disclosed couplings, direct couplings, or communication connections may be implemented through some interfaces. The indirect coupling or communication connection between devices or units may be implemented in an electronic form, a mechanical form, or another form.

[0286] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units. In other words, they may be located in one place or distributed over multiple network units. To achieve the purpose of the solution of the embodiment, some or all of the units may be selected based on actual requirements.

[0287] In addition, the functional units of the embodiments of this application may be integrated into one processing unit, each unit may exist physically alone, or two or more units may be integrated into one unit.

[0288] If the function is implemented in the form of a software functional unit and sold or used as an independent product, the function may be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a part of the technical solution, may be implemented in the form of a software product. The computer software product is stored in a storage medium and includes several instructions that instruct a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method described in the embodiments of this application. The aforementioned storage medium includes any medium that can store program code, such as a USB flash drive, a removable hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0289] The foregoing description is only a specific implementation of this application and is not intended to limit the protection scope of this application. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application shall be within the protection scope of this application. Therefore, the protection scope of this application shall be subject to the protection scope of the claims.

Description of Reference Signs

[0290] 111 Processor 112 Transceiver 113 Memory 600 Communication Device 601 Transceiver Module 602 Processing Module 1000 Communication Device

Claims

1. A cell measurement method, comprising: a step of receiving, by a terminal device, first indication information, wherein the first indication information indicates at least one candidate cell and a first cell set corresponding to a first candidate cell among the at least one candidate cell, and the first cell set includes at least one cell; a step of measuring, by the terminal device, cells within the first cell set based on the first indication information, wherein a serving cell of the terminal device is the first candidate cell.

2. The method according to claim 1, wherein the at least one candidate cell is at least one candidate primary-secondary cell for conditional primary-secondary cell addition (CPA) or conditional primary-secondary cell change (CPC).

3. The method according to claim 1, wherein the at least one candidate cell is at least one candidate primary cell for layer 1 / layer 2 handover.

4. The first indication information indicating the first cell set corresponding to the first candidate cell among the at least one candidate cell is: the first indication information indicating the first cell set corresponding to the first candidate cell by indicating a physical cell identifier (PCI) of the at least one cell; the first indication information indicating the first cell set corresponding to the first candidate cell by indicating a configuration identifier of the at least one cell, wherein the configuration identifier is associated with a configuration of a candidate cell among the at least one candidate cell; or the first indication information indicating the first cell set corresponding to the first candidate cell by using bitmapping indication information. The method according to any one of claims 1 to 3.

5. The method according to any one of claims 1 to 4, wherein the at least one cell included in the first cell set is a cell among the at least one candidate cell.

6. A cell measurement method, comprising: A step of determining first indication information by a network device, wherein the first indication information indicates at least one candidate cell and a first cell set corresponding to a first candidate cell among the at least one candidate cell, and the first cell set includes at least one cell. A method including the step of transmitting, by the network device, the first indication information.

7. The method according to claim 6, wherein the at least one candidate cell is at least one candidate primary secondary cell for conditional primary secondary cell addition (CPA) or conditional primary secondary cell change (CPC).

8. The method according to claim 6, wherein the at least one candidate cell is at least one candidate primary cell for layer 1 / layer 2 handover.

9. The fact that the first indication information indicates the first cell set corresponding to the first candidate cell among the at least one candidate cell is the first indication information indicates the first cell set corresponding to the first candidate cell by indicating the physical cell identifier (PCI) of the at least one cell, the first indication information indicates the first cell set corresponding to the first candidate cell by indicating a configuration identifier of the at least one cell, wherein the configuration identifier is associated with the configuration of a candidate cell among the at least one candidate cell, or the first indication information indicates the first cell set corresponding to the first candidate cell by using bitmap indication information, the method according to any one of claims 6 to 8.

10. The method according to any one of claims 6 to 9, wherein the at least one cell included in the first cell set is a cell among the at least one candidate cell.

11. A communication method, a step of receiving, by a terminal device, a first message, wherein the first message includes configuration information of a candidate cell. When the first condition is satisfied, a step of transmitting, by the terminal device, a second message to a first network device, wherein the second message is used to request updating the configuration information of the candidate cell, and the first condition is the following, namely, the signal quality of the serving cell is equal to or lower than a first threshold; the number of candidate cells that can be detected by the terminal device is equal to or lower than a first number; or the signal quality of the candidate cell is equal to or lower than a second threshold, including at least one of the above, and the method including the step.

12. A communication method, comprising: a step of receiving, by a terminal device, a first message, wherein the first message includes configuration information of a candidate cell; and when a second condition is satisfied, a step of triggering, by the terminal device, transmission of a measurement report to a first network device, wherein the measurement report includes the signal quality of the candidate cell, and the second condition is the following, namely, the signal quality of the serving cell is equal to or lower than a second threshold; the number of detectable candidate cells is equal to or lower than a second number; the signal quality of the candidate cell is equal to or lower than a third threshold; the serving cell is switched to a first cell, and the first cell is a cell within a first cell set; the signal quality of one or more cells other than the candidate cell is equal to or higher than a fourth threshold, including at least one of the above, and the method including the step.

13. The configuration information of the candidate cell is conditional primary secondary cell addition (CPA) or conditional primary secondary cell change (CPC) configuration information, and the second message is used to update the CPA or CPC configuration information, or The configuration information of the candidate cell is configuration information of a candidate cell for a layer 1 / layer 2 handover, and the second message is used to request updating the configuration information of the layer 1 / layer 2 handover. The method according to claim 11.

14. a step of receiving, by the terminal device, a third message, wherein the third message instructs the terminal device to switch to a target cell, and the target cell does not belong to the candidate cell. The terminal device switches to the target cell and performs the following, namely, assuming that the configuration information of the candidate cell is valid or stored, or determining whether the configuration information of the candidate cell is valid or invalid based on the instruction information from the first network device, The method according to any one of claims 11 to 13, further comprising the step of performing any one of the above.

15. The step of triggering, by the terminal device, a radio resource control (RRC) re-establishment process, wherein the cell selected in the RRC re-establishment process belongs to the first network device, The step of the terminal device assuming that the configuration information of the candidate cell is valid or stored. The method according to any one of claims 11 to 14.

16. A communication method, comprising: Determining, by a first network device, configuration information of a candidate cell; Transmitting, by the first network device, a first message, wherein the first message includes the configuration information of the candidate cell; Receiving, by the first network device, the first message or a measurement report, wherein the first message is used to request updating of the configuration information of the candidate cell, and the measurement report includes signal quality of the candidate cell.

17. The configuration information of the candidate cell is conditional primary secondary cell addition (CPA) or conditional primary secondary cell change (CPC) configuration information, and the first message is used to request updating of the CPA or CPC configuration information, or The configuration information of the candidate cell is configuration information of a candidate cell for layer 1 / layer 2 handover, and the first message is used to request updating of the configuration information of the layer 1 / layer 2 handover. The method according to claim 16.

18. A communication device comprising a module configured to execute the method according to any one of claims 1 to 5, claims 6 to 10, claims 11 to 15, or claims 16 or 17.

19. A communication device, wherein the structure of the communication device comprises a processor and further comprises a memory, the processor being connected to the memory and configured to execute computer program instructions stored in the memory so that the communication device can execute the method according to any one of claims 1 to 5 or claims 11 to 15, or execute the method according to any one of claims 6 to 10 or claim 16 or 17.

20. A readable storage medium configured to store instructions, wherein when the instructions are executed, the method according to any one of claims 1 to 5 or claims 11 to 15 is implemented, or the method according to any one of claims 6 to 10 or claim 16 or 17 is implemented.

21. A computer program including instructions, wherein when the instructions are executed on a communication device, the method according to any one of claims 1 to 17 is implemented.

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