Information transmission method and apparatus

Abstract

To provide an information transmission method and device for optimizing handover parameters under a conditional handover (CHO) mechanism.SOLUTION: In a mobile communication system, a terminal device receives CHO configuration information including information about candidate cells and a handover trigger condition from a first network device, and after performing CHO, transmits a first failure cause value corresponding to a candidate target cell and / or a second failure cause value corresponding to a determination target cell to a second network device during the CHO. The second network device transmits the first failure cause value and / or second failure cause value received from the terminal device to the first network device. The candidate target cell is a cell which satisfies the handover trigger condition and which the terminal device has failed to access among the candidate cells, and the determination target cell is a cell which does not satisfy the handover trigger condition among the candidate cells.SELECTED DRAWING: Figure 6

Description

Technical Field

[0002] This application relates to the field of communications, and in particular, to information transmission methods and apparatuses.

Background Art

[0003] In a mobile communication system, in the conventional handover procedure, the mobility management of the connected terminal device is controlled by the network device. Specifically, by sending a handover message, the network device indicates to the terminal device which cell to hand over to and how to perform the handover. The conventional handover mechanism may include sending a handover message to the terminal device by the source network device (i.e., the network device to which the source cell belongs) so that the terminal device is controlled to hand over from the source cell to the target cell. The handover message is a radio resource control (RRC) message. Specifically, the RRC message may be an RRC reconfiguration message carrying a reconfiguration with sync information element, or an RRC connection reconfiguration message carrying a mobility control info information element. After receiving the handover message, the terminal device accesses the target cell according to the content included in the handover message. Therefore, the successful transmission of the handover message is a necessary condition for ensuring the success of the handover under the conventional handover mechanism. However, in a long term evolution (LTE) system or a fifth-generation (5G) mobile communication technology (especially in a high-frequency scenario), the failure of the transmission of the handover message is caused by a rapid deterioration of the channel quality, a rapid movement of the terminal device, a blockage by an object, or a long period of measurement or handover preparation, etc., resulting in a handover failure and a possible decrease in the handover success rate.

[0004] In view of the above problems, in the prior art, a conditional handover (CHO) mechanism has been proposed to improve the handover success rate. Specifically, the source network device transmits conditional handover configuration information to the terminal device when the source link is of relatively high quality. The configuration information includes handover trigger conditions configured by the network device for the terminal device and information regarding one or more candidate cells corresponding to the handover trigger conditions. After receiving the conditional handover configuration information, the terminal device determines whether each candidate cell meets the handover trigger conditions based on the configuration information, and uses the candidate cell that meets the handover trigger conditions as the target cell to perform a handover to the target cell. In the CHO mechanism, the source network device transmits conditional handover configuration information to the terminal device when the source link has relatively high communication quality, and as a result, the success rate of transmitting the configuration information is ensured. Furthermore, based on the configuration information, the terminal device selects the target cell at its own discretion and performs a handover, and as a result, the handover success rate is improved.

[0005] In both the conventional handover mechanism and the CHO mechanism, handover-related parameters are always one of the important factors that directly affect the handover success rate. In the conventional handover mechanism, a mobility robustness optimization (MRO) mechanism has been introduced to optimize handover parameters. Specifically, the terminal device transmits the relevant information generated in the mobility impairment procedure to the network device, and then the network device optimizes the handover parameters according to the relevant information reported by the terminal device. Under the existing MRO mechanism, the terminal device generally records the relevant information generated in the mobility impairment procedure and transmits the relevant information to the network device in the following two scenarios: (1) a scenario where the terminal device fails to receive a handover message and a radio link failure (RLF) occurs; and (2) a scenario where the terminal device successfully receives the handover message but fails to access the target cell or an RLF occurs immediately after successfully accessing the target cell.

[0006] However, due to the differences between the CHO mechanism and the conventional handover mechanism, the MRO mechanism in the existing conventional handover mechanism is not suitable for optimizing handover parameters under the CHO mechanism. Therefore, a good mechanism for accurately and timely optimizing handover parameters under the conditional handover mechanism is not currently available. SUMMARY OF THE INVENTION MEANS FOR SOLVING THE PROBLEM

[0007] In view of the foregoing problems, embodiments of the present application provide an information transmission method, apparatus, and system for optimizing handover parameters under a conditional handover mechanism.

[0008] To achieve the foregoing objectives, embodiments of the present application adopt the following technical solutions.

[0009] According to a first aspect, an information transmission method and a corresponding communication device are provided. In this solution, the terminal device receives conditional handover configuration information. The conditional handover configuration information includes a handover trigger condition and information about M candidate cells, where M is a positive integer. The terminal device transmits a first failure cause value corresponding to at least one candidate target cell and / or a second failure cause value corresponding to at least one determination target cell. At least one candidate target cell includes X cells among the M candidate cells that satisfy the handover trigger condition, and at least one determination target cell includes Y cells among the M candidate cells that do not satisfy the handover trigger condition. X and Y are natural numbers, and X + Y is less than or equal to M. In this embodiment of the present application, the terminal device may transmit a first failure cause value corresponding to a candidate target cell and / or a second failure cause value corresponding to a determination target cell under a conditional handover mechanism. Therefore, the network side can optimize the handover parameters according to the failure cause values. Therefore, the handover parameters can be optimized under the conditional handover mechanism based on the solution provided in this embodiment of the present application.

[0010] In a possible design, the terminal device may further transmit one or more of information about the source cell, information about the candidate target cell, first time information corresponding to each of the at least one candidate target cell, information about the determination target cell, and second time information corresponding to each of the at least one determination target cell. In this embodiment of the present application, the terminal device may transmit one or more of the foregoing information under a conditional handover mechanism. Therefore, the network side can more comprehensively optimize the handover parameters according to various information reported by the terminal device, so that the configured handover parameters become more reasonable in subsequent candidate cell configurations.

[0011] In a possible design, when the terminal device successfully accesses the first target cell, the terminal device may further send one or more of the information about the first target cell, as well as the third cause value and the third time information corresponding to the first target cell. The first target cell is the cell successfully accessed by the terminal device among the M candidate cells. In this embodiment of the present application, the terminal device further sends the related information generated when the conditional handover is successful. Therefore, when configuring candidate cells in the subsequent CHO procedure, the cell where the conditional handover is successfully executed may be preferentially configured as a candidate cell, so that the conditional handover configuration information configured by the network side becomes more reasonable. In addition, when the conditional handover mechanism is a backup mechanism for the conventional handover, the related information generated when the conditional handover is successful is reported to the network device, so that the network side recognizes that the conventional handover procedure is not triggered by the network side even though the conventional handover procedure is configured by the network side, or recognizes that the conventional handover procedure executed by the terminal device according to the conventional handover message fails. Therefore, the network side can adjust the related parameters in the conventional handover procedure and / or the conditional handover procedure according to the related information generated when the conditional handover is successful and reported by the terminal device. In this way, after triggering the conditional handover procedure, the network side can continue to trigger the conventional handover procedure, and as a result, the reliability of the system is improved.

[0012] In a possible design, before the terminal device successfully accesses the first target cell, it may further receive an RRC reconfiguration message. The RRC reconfiguration message is used to instruct the terminal device to perform a conventional handover. The RRC reconfiguration message includes information about the second target cell. The terminal device may access the second target cell according to the RRC reconfiguration message, or the terminal device may determine that the RRC reconfiguration message has not been received. In this embodiment of the present application, before the success of the conditional handover, the terminal device receives an RRC reconfiguration message used to instruct the terminal device to perform a conventional handover, and may perform a conventional handover according to the RRC reconfiguration message. Therefore, on the one hand, the conditional handover mechanism functions as an auxiliary mechanism for the conventional handover mechanism, and on the other hand, the conditional handover can be further performed in the case of failure of the conventional handover. As a result, the drawbacks of the conventional handover are compensated, and the handover success rate is increased.

[0013] According to a second aspect, an information transmission method and a corresponding communication device are provided. In this solution, a first network device transmits conditional handover configuration information to a terminal device. The conditional handover configuration information includes a handover trigger condition and information about M candidate cells, where M is a positive integer. The first network device receives, from a second network device, a first failure cause value corresponding to at least one candidate target cell and / or a second failure cause value corresponding to at least one cell to be determined. At least one candidate target cell satisfies the handover trigger condition and includes X cells in which the terminal device fails to access among the M candidate cells, and at least one cell to be determined includes Y cells that do not satisfy the handover trigger condition among the M candidate cells. X and Y are natural numbers, and X + Y is less than or equal to M. For the technical effects brought by the second aspect, reference may be made to the technical effects brought by the first aspect, and details are not repeated here.

[0014] In a possible design, the first network device may further receive from the second network device one or more of the following information, namely, information about the source cell, information about the candidate target cell, first time information corresponding to each of at least one candidate target cell, information about the cell to be determined, and second time information corresponding to each of at least one cell to be determined.

[0015] In a possible design, the first network device may further receive from the second network device one or more of the following information, namely, information about the first target cell, and the third cause value and the third time information corresponding to the first target cell. The first target cell is the cell that has been successfully accessed by the terminal device among the M candidate cells.

[0016] In a possible design, the first network device may optimize handover parameters according to one or more of the received first failure cause value and / or second failure cause value and other information described above under a conditional handover mechanism. In a possible implementation, when the first network device receives the first failure cause value and / or the second failure cause value, for example, when the first network device subsequently configures candidate cells in the next or subsequent CHO procedure, candidate target cells may be excluded, that is, candidate target cells are no longer configured as candidate cells. In this way, in the next or subsequent conditional handover, the terminal device no longer needs to determine whether the candidate target cell meets the handover trigger condition, and as a result, the energy consumption of the terminal device and the complexity of the implementation of the terminal device are reduced. Alternatively, if event A3 is configured in the conditional handover configuration information and parameter Q is configured for event A3, the first network device may change the value of the configured parameter Q when subsequently configuring the handover trigger condition. In another possible implementation, for a cell where the conditional handover fails (such as a candidate target cell or a cell to be determined), within the time interval indicated by the first time information, if the network device reconfigures the relevant parameters within the handover trigger condition corresponding to the cell where the conditional handover fails (using A3 as an example, parameter R is reconfigured), the network device may delete, discard, or ignore the relevant information corresponding to the cell where the conditional handover fails received from the terminal device, and may not adjust the relevant parameters within the handover trigger condition corresponding to the cell where the conditional handover fails. In another possible implementation, after receiving the MRO-related information including the relevant information regarding the failure of the conventional handover, the first network device may not configure the second target cell as a candidate cell or a target cell when subsequently configuring candidate cells. Alternatively, in subsequent conventional handover procedures, the first network device may adjust the parameters of the relevant events in the measurement configuration.For example, in a measurement configuration, if event A3 is configured and an offset P is configured for event A3, the first network device may change the value of P to achieve the purpose of optimization.

[0017] According to a third aspect, an information transmission method and a corresponding communication device are provided. In this solution, the second network device receives, from the terminal device, a first failure cause value corresponding to at least one candidate target cell and / or a second failure cause value corresponding to at least one cell to be determined. The at least one candidate target cell satisfies a handover trigger condition and includes X cells among M candidate cells where the terminal device has failed to access, and the at least one cell to be determined includes Y cells among M candidate cells that do not satisfy the handover trigger condition. X and Y are natural numbers, X + Y is less than or equal to M, and the M candidate cells and the handover trigger condition are configured by conditional handover configuration information. The second network device transmits the first failure cause value and / or the second failure cause value to the first network device. Regarding the technical effects brought about by the third aspect, reference may be made to the technical effects brought about by the first aspect, and details are not repeated here.

[0018] In a possible design, the second network device may further receive, from the terminal device, one or more of the following information, that is, information about the source cell, information about the candidate target cell, first time information corresponding to each of the at least one candidate target cell, information about the cell to be determined, and second time information corresponding to each of the at least one cell to be determined, and transmit one or more of the following information to the first network device.

[0019] In a possible design, the second network device may further receive from the terminal device one or more of the following information, namely, information regarding the first target cell, and one or more of the third cause value and the third time information corresponding to the first target cell, and transmit one or more of these following information to the first network device. The first target cell is a cell that has been successfully accessed by the terminal device among the M candidate cells.

[0020] In a possible design, the second network device may optimize the handover parameters according to one or more of the received first failure cause value and / or the second failure cause value and other information described above under a conditional handover mechanism. For the method of optimizing the handover parameters by the second network device under the conditional handover mechanism, reference may be made to the method used by the first network device, and the details are not repeated here.

[0021] According to a fourth aspect, an information transmission method and a corresponding communication device are provided. In this solution, a first network device transmits conditional handover configuration information to a terminal device. The conditional handover configuration information includes a handover trigger condition and information about M candidate cells, where M is a positive integer. A second network device receives, from the terminal device, a first failure cause value corresponding to at least one candidate target cell and / or a second failure cause value corresponding to at least one determination target cell. The second network device transmits the first failure cause value and / or the second failure cause value to the first network device. The at least one candidate target cell includes X cells that satisfy the handover trigger condition and to which the terminal device fails to access among the M candidate cells, and the at least one determination target cell includes Y cells that do not satisfy the handover trigger condition among the M candidate cells. X and Y are natural numbers, and X + Y is less than or equal to M. Regarding the technical effects brought about by the fourth aspect, reference may be made to the technical effects brought about by the first aspect, and the details are not repeated here. In a possible design related to the first aspect, the second aspect, the third aspect, or the fourth aspect, the first failure cause value indicates that the candidate target cell satisfies the handover trigger condition, but the terminal device fails to access the candidate target cell. Alternatively, the first failure cause value includes a first-level failure cause value and a second-level failure cause value. The first-level failure cause value indicates that the conditional handover of the terminal device fails. The second-level failure cause value indicates that the candidate target cell satisfies the handover trigger condition, but the terminal device fails to access the candidate target cell.

[0022] In relation to the first aspect, or the second aspect, or the third aspect, or the fourth aspect, in a possible design, the second failure cause value indicates that the cell to be determined does not satisfy the handover trigger condition. Alternatively, the second failure cause value includes the failure cause value at the third level and the failure cause value at the fourth level. The failure cause value at the third level indicates that the conditional handover of the terminal device has failed. The failure cause value at the fourth level indicates that the cell to be determined does not satisfy the handover trigger condition.

[0023] In relation to the first aspect, or the second aspect, or the third aspect, in a possible design, the first time information includes information regarding the time interval from the time when the terminal device receives the conditional handover configuration information to the time when the terminal device triggers a handover to the first candidate target cell, information regarding the time interval from the time when the terminal device triggers a handover to the first candidate target cell to the time when the terminal device fails to access the first candidate target cell, and information regarding the time interval from the time when the terminal device fails to access the first candidate target cell to the time when the terminal device transmits the first failure cause value and / or the second failure cause value. The first candidate target cell is any one of at least one candidate target cell.

[0024] In relation to the first aspect, or the second aspect, or the third aspect, in a possible design, the second time information includes information regarding the time interval from the time when the terminal device receives the conditional handover configuration information to the time when the terminal device determines that the first cell to be determined does not satisfy the handover trigger condition, and information regarding the time interval from the time when the terminal device determines that the first cell to be determined does not satisfy the handover trigger condition to the time when the terminal device transmits the first cause value and / or the second cause value. The first cell to be determined is any one of at least one cell to be determined. Alternatively, the second time information includes information regarding the time interval from the time when the terminal device receives the conditional handover configuration information to the time when the terminal device stops determining whether the first cell to be determined satisfies the handover trigger condition, and information regarding the time interval from the time when the terminal device stops determining whether the first cell to be determined satisfies the handover trigger condition to the time when the terminal device transmits the first cause value and / or the second cause value.

[0025] In relation to the first aspect, or the second aspect, or the third aspect, in a possible design, the third cause value indicates that the terminal device has successfully performed a conditional handover.

[0026] In relation to the first aspect, or the second aspect, or the third aspect, in a possible design, the third time information includes information regarding the time interval from the time when the terminal device receives the conditional handover configuration information to the time when the terminal device triggers a handover to the first target cell, information regarding the time interval from the time when the terminal device triggers a handover to the first target cell to the time when the terminal device successfully accesses the first target cell, and information regarding the time interval from the time when the terminal device successfully accesses the first target cell to the time when the terminal device transmits one or more of the information regarding the first target cell, the third cause value, and the third time information.

[0027] According to a fifth aspect, a communication device for implementing any of the foregoing methods is provided. The communication device may be a terminal device according to the first aspect, or a device including this terminal device, or the communication device may be a first network device according to the second aspect, or a device including this first network device, or the communication device may be a second network device according to the third aspect, or a device including this second network device. The communication device includes a module, unit, or means for implementing the method. The module, unit, or means may be implemented by hardware or software, or by corresponding software executed by hardware. The hardware or software includes one or more modules or units corresponding to the functions.

[0028] In a sixth aspect, a communication device including a processor and a memory is provided. The memory is configured to store computer instructions that cause the communication device to execute the method according to any of the foregoing aspects when executed by the processor. The communication device may be a terminal device according to the first aspect, or a device including this terminal device, or the communication device may be a first network device according to the second aspect, or a device including this first network device, or the communication device may be a second network device according to the third aspect, or a device including this second network device.

[0029] According to a seventh aspect, a communication device including a processor is provided. The processor is coupled to a memory and configured to read instructions in the memory and execute a method according to any of the foregoing aspects based on the instructions. The communication device may be a terminal device according to the first aspect, or a device including this terminal device, or the communication device may be a first network device according to the second aspect, or a device including this first network device, or the communication device may be a second network device according to the third aspect, or a device including this second network device.

[0030] According to an eighth aspect, a computer-readable storage medium is provided. The computer-readable storage medium stores instructions that enable a computer to execute a method according to any of the foregoing aspects when executed on the computer.

[0031] According to a ninth aspect, a computer program product including instructions is provided. When the computer program product is executed on a computer, the computer is capable of executing a method according to any of the foregoing aspects.

[0032] According to a tenth aspect, a communication device (for example, the communication device may be a chip or a chip system) is provided. The communication device includes a processor configured to implement the functions described in any of the foregoing aspects. In a possible design, the communication device further includes a memory. The memory is configured to store necessary program instructions and data. When the communication device is a chip system, the communication device may include a chip or may include a chip and another discrete element.

[0033] Regarding the technical effects brought about by any design according to the fifth aspect to the tenth aspect, reference may be made to the technical effects brought about by various designs according to the first aspect, or the second aspect, or the third aspect, or the fourth aspect, and the details are not repeated here.

[0034] According to the 11th aspect, a communication system is provided. The communication system may include the first network device and the second network device according to the 5th aspect to the 10th aspect.

[0035] According to the 12th aspect, a communication system is provided. The communication system may include the first network device, the second network device, and the terminal device according to the 5th aspect to the 10th aspect.

Brief Description of the Drawings

[0036]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Modes for Carrying Out the Invention

[0037] Hereinafter, in relation to the accompanying drawings in the embodiments of the present application, the technical solutions in the embodiments of the present application will be described. In the description of the present application, unless otherwise specified, " / " represents an "or" relationship between the previous object and the subsequent object. For example, "A / B" may represent A or B. The term "and / or" used in the present application may simply describe the association relationship between related objects and represents three possible relationships. For example, "A and / or B" may represent three scenarios: only A, both A and B, and only B. In that case, A and B may be singular or plural. In addition, in the description of the present application, "a plurality of" means two or more. "At least one of (the following)" or similar expressions mean any combination of the items mentioned, that is, a combination of one or more of the items. For example, the phrase "at least one of a, b, or c" represents a, b, c, a-b, a-c, b-c, or a-b-c. In that case, a, b, and c may be singular or plural. In addition, to facilitate a clear description of the technical solutions in the embodiments of the present application, items that perform substantially the same function or bring similar effects are distinguished in the embodiments of the present application by words such as "first" and "second". Those skilled in the art will understand that words such as "first" and "second" do not limit the number or the order of operations, and the objects modified by words such as "first" and "second" are not necessarily different from each other.

[0038] FIG. 1 shows a communication system 10 according to an embodiment of the present application. The communication system 10 includes a terminal device, a first network device, and a second network device.

[0039] As an example, using the interaction between the terminal device shown in FIG. 1, the first network device, and the second network device, in this embodiment of the present application, the first network device transmits conditional handover configuration information to the terminal device. The conditional handover configuration information includes information about candidate cells and handover trigger conditions. After receiving the conditional handover configuration information and performing the conditional handover, the terminal device transmits, during the conditional handover, a first failure cause value corresponding to a candidate target cell and / or a second failure cause value corresponding to a cell to be determined to the second network device. The candidate target cell is a candidate cell that satisfies the handover trigger condition. The cell to be determined is a candidate cell that does not satisfy the handover trigger condition. After receiving the first failure cause value and / or the second failure cause value from the terminal device, the second network device transmits the first failure cause value and / or the second failure cause value to the first network device. In this way, the first network device or the second network device can optimize the handover parameters according to the failure cause value. Therefore, the handover parameters can be optimized under the conditional handover mechanism based on the solution provided in this embodiment of the present application.

[0040] Optionally, FIG. 2 is a schematic structural diagram of a first network device, a second network device, and a terminal device according to an embodiment of the present application.

[0041] The terminal device includes at least one processor (in FIG. 2, one processor 401 is included as an example) and at least one transceiver (in FIG. 2, one transceiver 403 is included as an example). Optionally, the terminal device may further include at least one memory (in FIG. 2, one memory 402 is included as an example), at least one output device (in FIG. 2, one output device 404 is included as an example), and at least one input device (in FIG. 2, one input device 405 is included as an example).

[0042] The processor 401, the memory 402, and the transceiver 403 are connected via a communication line. The communication line may include a path for transmitting information between the aforementioned components.

[0043] The processor 401 can be a general-purpose central processing unit (CPU), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to control the execution of a program in the solution provided in this application. In a particular embodiment, as one embodiment, the processor 401 may also include multiple CPUs, and the processor 401 can be a single-core (single-CPU) processor or a multi-core (multi-CPU) processor. The processor here can mean one or more devices, circuits, or processing cores configured to process data (such as computer program instructions).

[0044] Memory 402 can be a storage device. For example, Memory 402 can be a read-only memory (ROM) or another type of static storage device that can store static information and instructions, a random access memory (RAM) or another type of dynamic storage device that can store information and instructions, an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or another optical disc storage, optional disc storage (including compact discs, laser discs, optical discs, digital versatile discs, and Blu-ray discs, etc.), a magnetic disk storage medium or another magnetic storage device, or any other medium that holds or stores the desired program code in the form of instructions or data structures and is accessible by a computer, but is not limited thereto. Memory 402 can exist independently and can be connected to Processor 401 via a communication line. Memory 402, alternatively, may be integrated with Processor 401.

[0045] Memory 402 is configured to store computer-executable instructions for executing the solutions of the present application, and the execution is controlled by Processor 401. Specifically, Processor 401 is configured to execute the computer-executable instructions stored in Memory 402 in order to implement the information transmission method according to the embodiments of the present application. Optionally, the computer-executable instructions in this embodiment of the present application are also known as application program code or computer program code. This is not particularly limited in this embodiment of the present application.

[0046] Transceiver 403 can be any device such as a transceiver, and is configured to communicate with another device or a communication network such as Ethernet, a radio access network (RAN), or a wireless local area network (WLAN). Transceiver 403 includes a transmitter (Tx) and a receiver (Rx). The transceiver can also be an input / output interface.

[0047] Output device 404 communicates with processor 401 and can display information in various forms. For example, output device 404 may be a liquid crystal display (LCD), a light emitting diode (LED) display device, a cathode ray tube (CRT) display device, or a projector.

[0048] The input device 405 communicates with the processor 401 and can receive user input in various forms. For example, the input device 405 may be a mouse, keyboard, touch screen device, or sensor device. The first network device includes one or more processors (in FIG. 2, one processor 301a is included as an example), at least one transceiver (in FIG. 2, one transceiver 303a is included as an example), and at least one network interface (in FIG. 2, one network interface 304a is included as an example). Optionally, the first network device may further include at least one memory (in FIG. 2, one memory 302a is included as an example). The processor 301a, memory 302a, transceiver 303a, and network interface 304a are connected via communication lines. The network interface 304a is configured to be connected to the core network device via a link (such as the S1 interface, not shown in FIG. 2) or to the network interface of another network device via a wired or wireless link (such as the X2 interface). This is not particularly limited in this embodiment of the present application. In addition, for the related descriptions of the processor 301a, memory 302a, and transceiver 303a, reference may be made to the descriptions of the processor 401, memory 402, and transceiver 403 in the terminal device, and the details are not repeated here.

[0049] The second network device includes one or more processors (in FIG. 2, one processor 301b is included as an example), at least one transceiver (in FIG. 2, one transceiver 303b is included as an example), and at least one network interface (in FIG. 2, one network interface 304b is included as an example). Optionally, the second network device may further include at least one memory (in FIG. 2, one memory 302b is included as an example). The processor 301b, the memory 302b, the transceiver 303b, and the network interface 304b are connected via communication lines. The network interface 304b is connected to the core network device via a link (such as the S1 interface, not shown in FIG. 2), or is configured to be connected to the network interface of another network device via a wired or wireless link (such as the X2 interface). This is not particularly limited in this embodiment of the present application. In addition, for the related descriptions of the processor 301b, the memory 302b, and the transceiver 303b, reference may be made to the descriptions of the processor 401, the memory 402, and the transceiver 403 in the terminal device, and the details are not repeated here.

[0050] In another possible embodiment, FIG. 3 shows a communication system 30 according to an embodiment of the present application. The communication system includes a network device and a terminal device connected to the network device. Optionally, the network device may be connected to a plurality of terminal devices. This is not particularly limited in the present application.

[0051] As an example, using the interaction between the terminal device and the network device shown in FIG. 3, in this embodiment of the present application, the network device transmits conditional handover configuration information to the terminal device. The conditional handover configuration information includes information about candidate cells and handover trigger conditions. After receiving the conditional handover configuration information and performing the conditional handover, the terminal device transmits, during the conditional handover, a first failure cause value corresponding to a candidate target cell and / or a second failure cause value corresponding to a cell to be determined to the network device. The candidate target cell is a candidate cell that satisfies the handover trigger condition. The cell to be determined is a candidate cell that does not satisfy the handover trigger condition. In this way, the network device can optimize the handover parameters according to the failure cause value. Therefore, the handover parameters can be optimized under the conditional handover mechanism based on the solution provided in this embodiment of the present application.

[0052] FIG. 4 is a schematic structural diagram of a network device and a terminal device according to an embodiment of the present application. For the schematic structural diagram of the terminal device, reference may be made to the schematic structural diagram shown in FIG. 2, and details are not repeated here.

[0053] The network device includes at least one processor (in FIG. 4, one processor 301 is included as an example), at least one transceiver (in FIG. 4, one transceiver 303 is included as an example), and at least one network interface (in FIG. 4, one network interface 304 is included as an example). Optionally, the network device may further include at least one memory (in FIG. 4, one memory 302 is included as an example). The processor 301, the memory 302, the transceiver 303, and the network interface 304 are connected via communication lines. The network interface 304 is configured to be connected to a core network device via a link (such as an S1 interface) or to the network interface of another network device via a wired or wireless link (such as an X2 interface) (this connection is not shown in FIG. 4). This is not particularly limited in this embodiment of the present application. In addition, for the related descriptions of the processor 301, the memory 302, and the transceiver 303, reference may be made to the descriptions of the processor 401, the memory 402, and the transceiver 403 in the terminal device, and the details will not be repeated here.

[0054] Optionally, the network device (including the first network device or the second network device) and the terminal device in the embodiments of the present application may sometimes be referred to as communication devices, and may be general-purpose devices or dedicated devices. This is not particularly limited in the embodiments of the present application.

[0055] Optionally, the network device (including the first network device or the second network device) in the embodiments of the present application is a device that connects a terminal device to a wireless network, such as an evolved Node B (eNB) in an LTE system, a base station in a 5G network or a future evolved public land mobile network (PLMN), a broadband network gateway (BNG), an aggregation switch, or a non-3rd generation partnership project (3GPP (registered trademark)) access device, etc. This is not particularly limited in the embodiments of the present application. Optionally, the base station in the embodiments of the present application may include various forms of base stations such as a macro base station, a micro base station (also called a small cell), a relay station, or an access point. This is not particularly limited in the embodiments of the present application.

[0056] Optionally, the terminal device in the embodiments of the present application may be a device configured to implement a wireless communication function, such as a terminal or a chip that can be used in a terminal. The terminal may be a user equipment (UE) in a 5G network or a future evolved PLMN, an access terminal, a terminal unit, a terminal station, a mobile station, a remote station, a remote terminal, a mobile device, a wireless communication device, a terminal agent, or a terminal device, etc. The access terminal may be a cellular phone, a cordless phone, a session initiation protocol (SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), a wirelessly communicable handheld device, a computing device, another processing device connected to a wireless modem, an in-vehicle device, a wearable device, a virtual reality (VR) terminal device, an augmented reality (AR) terminal device, a wireless terminal for industrial control, a wireless terminal for self-driving, a wireless terminal for remote medical treatment, a wireless terminal for smart grid, a wireless terminal for transportation safety, a wireless terminal for smart city, or a wireless terminal for smart home, etc. The terminal may be mobile or fixed.

[0057] For example, in relation to the schematic structural diagram of the terminal device shown in FIG. 2 or FIG. 4, FIG. 5 shows a specific structural form of the terminal device according to an embodiment of the present application.

[0058] In some embodiments, the functions of the processor 401 in FIG. 2 or FIG. 4 may be implemented by the processor 110 in FIG. 5.

[0059] In some embodiments, the functions of the transceiver 403 in FIG. 2 or FIG. 4 may be implemented by the antenna 1, antenna 2, mobile communication module 150, or wireless communication module 160 in FIG. 5, etc.

[0060] Antenna 1 and antenna 2 are configured to transmit and receive electromagnetic wave signals. Each antenna in the terminal device may be configured to target one or more communication frequency bands. Different antennas may be further multiplexed to improve the utilization rate of the antennas. For example, antenna 1 may be multiplexed as a diversity antenna for a wireless local area network. In some other embodiments, the antenna may be used with a tuning switch.

[0061] The mobile communication module 150 may provide wireless communication solutions used in terminal devices, including wireless communications such as 2G, 3G, 4G, and 5G. The mobile communication module 150 may include at least one filter, switch, power amplifier, and low noise amplifier (LNA), etc. The mobile communication module 150 may receive electromagnetic waves via antenna 1, perform processing such as filtering and amplification on the received electromagnetic waves, and transmit the electromagnetic waves to the modem for demodulation. The mobile communication module 150 may further amplify the signal modulated by the modem, convert the signal into electromagnetic waves via antenna 1, and radiate the electromagnetic waves. In some embodiments, at least some functional modules of the mobile communication module 150 may be arranged in the processor 110. In some embodiments, at least some functional modules of the mobile communication module 150 and at least some modules of the processor 110 may be arranged in the same device.

[0062] The wireless communication module 160 can provide a wireless communication solution for use in a terminal device, including wireless communications such as a wireless local area network (WLAN) (such as a Wi-Fi network), Bluetooth (registered trademark) (BT), a global navigation satellite system (GNSS), frequency modulation (FM), near field communication (NFC), and infrared (IR). The wireless communication module 160 can be one or more devices integrating at least one communication processing module. The wireless communication module 160 receives electromagnetic waves via the antenna 2, performs frequency modulation and filtering processing on this electromagnetic wave signal, and transmits the processed signal to the processor 110. The wireless communication module 160 further receives, from the processor 110, a signal to be transmitted, performs frequency modulation and amplification on this signal, converts this signal into an electromagnetic wave via the antenna 2, and can radiate this electromagnetic wave. When the terminal device is a first device, the fact that the wireless communication module 160 can provide an NFC wireless communication solution for use in the terminal device means that the first device includes an NFC chip, and the NFC chip can enhance the NFC wireless communication function. When the terminal device is a second device, the fact that the wireless communication module 160 can provide an NFC wireless communication solution for use in the terminal device means that the device includes an electronic tag (such as a radio frequency identification (RFID) tag), and when the NFC chip of another device approaches the electronic tag, the other device can perform NFC wireless communication with the second device.

[0063] In some embodiments, the antenna 1 of the terminal device is coupled to the mobile communication module 150, and the antenna 2 is coupled to the wireless communication module 160. Thereby, the terminal device can communicate with the network and other devices by wireless communication technologies. The wireless communication technologies may include global system for mobile communications (GSM), general packet radio service (GPRS), code division multiple access (CDMA), wideband code division multiple access (WCDMA (registered trademark)), time-division code division multiple access (TD-SCDMA), long term evolution (LTE), BT, GNSS, WLAN, NFC, FM, or IR technology, etc. GNSS may include global positioning system (GPS), global navigation satellite system (GLONASS), beidou navigation satellite system (BDS), quasi-zenith satellite system (QZSS), or satellite based augmentation systems (SBAS).

[0064] In some embodiments, the functions of the memory 402 in FIG. 2 or FIG. 4 may be implemented by the internal memory 121 in FIG. 5, or an external memory (such as a Micro SD card) connected to the external memory interface 120.

[0065] In some embodiments, the functions of the output device 404 in FIG. 2 or FIG. 4 may be implemented by the display screen 194 in FIG. 5. The display screen 194 is configured to display images, videos, and the like. The display screen 194 includes a display panel.

[0066] In some embodiments, the functions of the input device 405 in FIG. 2 or FIG. 4 may be implemented by the mouse, keyboard, touch screen device, or sensor module 180 in FIG. 5. For example, as shown in FIG. 5, the sensor module 180 may include one or more of a pressure sensor 180A, a gyroscope sensor 180B, a barometric pressure sensor 180C, a magnetic sensor 180D, an acceleration sensor 180E, a distance sensor 180F, an optical proximity sensor 180G, a fingerprint sensor 180H, a temperature sensor 180J, a touch sensor 180K, an ambient light sensor 180L, or a bone conduction sensor 180M. This is not particularly limited in this embodiment of the present application.

[0067] In some embodiments, as shown in FIG. 5, the terminal device may further include one or more of an audio module 170, a camera 193, an indicator 192, a motor 191, a button 190, a SIM card interface 195, a USB interface 130, a charging management module 140, a power management module 141, or a battery 142. The audio module 170 may be connected to a speaker 170A (also referred to as a "loudspeaker"), a receiver 170B (also referred to as a "handset"), a microphone 170C (also referred to as a "microphone" or "mic"), or an earphone interface 170D. This is not particularly limited in this embodiment of the present application.

[0068] Of course, the structure shown in FIG. 5 does not constitute any specific limitation on the terminal device. For example, in some other embodiments of the present application, the terminal device may include more or fewer components than those shown in the figure, or some components may be combined, or some components may be divided, or the components may be arranged differently. The illustrated components may be implemented in the form of hardware, software, or a combination of software and hardware.

[0069] Hereinafter, as an example, the interaction between the first network device, the second network device, and the terminal device shown in FIG. 1 will be used to explain in detail the information transmission method in the embodiments of the present application.

[0070] It should be noted that the name of the message between network elements or the name of each parameter in the message in the embodiments of the present application is merely an example. In a specific embodiment, other names may be applied instead. This is not particularly limited in this embodiment of the present application.

[0071] FIG. 6 shows the information transmission method according to this embodiment of the present application. The information transmission method includes the following steps.

[0072] S601. The first network device sends message 1 to the terminal device.

[0073] Message 1 may include conditional handover configuration information. The conditional handover configuration information includes a handover trigger condition and information regarding M candidate cells. The first network device may be referred to as a source network device. That is, the first network device is a network device to which the source cell belongs. M is a positive integer. In other words, Message 1 may include information regarding one or more candidate cells. Naturally, the handover trigger condition and the information regarding M candidate cells may be transmitted in the same message or different messages. This is not limited in this embodiment of the present application.

[0074] Optionally, the conditional handover configuration information may further include information necessary for random access executed by the terminal device to access any one or more of the M candidate cells. The terminal device may start contention-free access to the candidate cell based on the information.

[0075] After receiving Message 1 transmitted by the first network device, the terminal device may determine whether any one of the M candidate cells satisfies the handover trigger condition based on the conditional handover configuration information included in Message 1 in order to determine at least one candidate target cell and / or at least one cell to be determined. At least one candidate target cell includes X cells that satisfy the handover trigger condition and to which the terminal device has failed to access among the M candidate cells, and at least one cell to be determined includes Y cells that do not satisfy the handover trigger condition among the M candidate cells. X is any natural number less than or equal to M, Y is any natural number less than or equal to M, and X + Y is less than or equal to M.

[0076] In this embodiment of the present application, it should be noted that unless otherwise specified, a failed access means that the terminal device has failed to access the cell. For example, the random access procedure executed by the terminal device for the cell fails. Alternatively, a failed access means that an RLF occurs in the cell that has been successfully accessed by the terminal device. For example, the terminal device succeeds in random access to the cell, but an RLF occurs in the cell within a preset time after the successful access of the terminal device. For example, the RLF occurs X seconds after the terminal device has successfully accessed the cell, and X may be specified by the protocol or configured by the network. This is not particularly limited in the present application.

[0077] S602. The terminal device transmits the MRO-related information to the second network device.

[0078] Optionally, in the CHO procedure in this embodiment of the present application, a terminal device having relevant capabilities, such as a terminal device capable of recording MRO-related information, may further record the MRO-related information of one or more candidate cells. Therefore, the terminal device may transmit this MRO-related information to the second network device.

[0079] Optionally, in this embodiment of the present application, the terminal device may transmit the MRO-related information to the second network device via an RRC message. For example, the RRC message may be a UE Information Response message or another RRC message or a message in another format. This is not particularly limited in the present application.

[0080] Optionally, in this embodiment of the present application, the second network device may request or trigger the terminal device to send MRO-related information, or the terminal device may trigger the transmission of MRO-related information (for example, the terminal device sends MRO-related information periodically or based on an event). This is not particularly limited in this embodiment of the present application.

[0081] Optionally, in this embodiment of the present application, after receiving a message containing MRO-related information from the terminal device, the second network device may forward this message to the first network device, whereby the first network device adjusts conditional handover-related parameters. Alternatively, the second network device may forward this message to the network device to which the corresponding candidate cell indicated in the MRO-related information belongs, whereby the network device to which the corresponding candidate cell belongs adjusts conditional handover-related parameters. Alternatively, the second network device may adjust conditional handover-related parameters based on the content of the message. For example, if the corresponding candidate cell included in the MRO information belongs to the second network device, the second network device may adjust conditional handover-related parameters. Optionally, after performing the corresponding processing (such as optimizing conditional handover parameters), the second network device may send the processing result to the first network device or the network device to which the corresponding candidate cell indicated in the MRO-related information belongs. This is not particularly limited in this embodiment of the present application.

[0082] After receiving a message containing MRO-related information from the terminal device, if the second network device determines to forward this message to the first network device, step S603 is executed.

[0083] S603. The second network device sends the MRO-related information to the first network device.

[0084] Optionally, in this embodiment of the present application, the second network device and the first network device may be the same network device. In this case, step S603 does not need to be executed. Alternatively, the second network device and the first network device may be different network devices. In this case, step S603 needs to be executed.

[0085] Steps S601 to S603:

[0086] The MRO-related information in this embodiment of the present application includes a first failure cause value corresponding to a candidate target cell and / or a second failure cause value corresponding to a cell to be determined.

[0087] For example, when there is a candidate target cell but no cell to be determined, the MRO-related information in this embodiment of the present application includes the first failure cause value corresponding to the candidate target cell. Alternatively, when there is a cell to be determined but no candidate target cell, the MRO-related information in this embodiment of the present application includes the second failure cause value corresponding to the cell to be determined. Alternatively, when both a candidate target cell and a cell to be determined exist, the MRO-related information in this embodiment of the present application includes both the first failure cause value corresponding to the candidate target cell and the second failure cause value corresponding to the cell to be determined.

[0088] Optionally, in this embodiment of the present application, the first failure cause value indicates that the candidate target cell meets the handover trigger condition, but the terminal device fails to access the candidate target cell. Alternatively, the first failure cause value includes two levels of cause values such as a first-level failure cause value and a second-level failure cause value. The first-level failure cause value indicates that the conditional handover of the terminal device fails, and the second-level failure cause value indicates that the candidate target cell meets the handover trigger condition, but the terminal device fails to access the candidate target cell.

[0089] Optionally, in this embodiment of the present application, with respect to the failure cause value at the second level, a possible expression form is that a new cause value is introduced to indicate that the candidate target cell meets the handover trigger condition, but the terminal device fails to access the candidate target cell. For example, the failure cause value at the second level may be represented by ConditionTriggerButAccessFailure (such as ConditionTriggerButAccessFailure), or the failure cause value at the second level may be represented in other forms. This is not particularly limited in this embodiment of the present application. Another possible expression form is to reuse the existing handover failure (HOF) cause value or RLF cause value. For example, the existing HOF may be reused. Specifically, the HOF cause value can be redefined to indicate that the cell meets the handover trigger condition, but the terminal device fails to access the cell. Optionally, in this embodiment of the present application, the correspondence between the candidate target cell and the first failure cause value may be that each candidate target cell corresponds to one first failure cause value, or multiple candidate target cells correspond to the same first failure cause value. In one example, the source cell is cell A, the conditional handover configuration information includes three candidate cells, cell B, cell C, and cell D, and cell B, cell C, and cell D are candidate target cells that meet the handover trigger condition, and the terminal device fails to access cell B, cell C, and cell D. Therefore, the correspondence between the candidate target cell and the first failure cause value may be that cell B corresponds to the first failure cause value 1, cell C corresponds to the first failure cause value 2, and cell D corresponds to the first failure cause value 3, or cell B and cell C both correspond to the first failure cause value 4, and cell D corresponds to the first failure cause value 5, or cell B, cell C, and cell D all correspond to the first failure cause value 6.

[0090] Optionally, in this embodiment of the present application, the second failure cause value indicates that the cell to be determined does not meet the handover trigger condition. Alternatively, the second failure cause value includes two levels of cause values such as the third-level failure cause value and the fourth-level failure cause value. The third-level failure cause value indicates that the conditional handover of the terminal device has failed. The fourth-level failure cause value indicates that the cell to be determined does not meet the handover trigger condition.

[0091] Optionally, in this embodiment of the present application, with respect to the fourth-level failure cause value, a possible expression form may be that a new cause value is introduced to indicate that the cell to be determined does not meet the handover trigger condition. For example, the fourth-level failure cause value may be represented by ConditionNotTrigger (such as ConditionNotTrigger), or the fourth-level failure cause value may be represented in other forms. This is not particularly limited in this embodiment of the present application. Another possible expression form is to reuse the existing HOF cause value or RLF cause value. For example, RLF may be reused. Specifically, the RLF cause value may be redefined to indicate that the cell does not meet the handover trigger condition.

[0092] Optionally, in this embodiment of the present application, the correspondence between the cell to be determined and the second failure cause value may be that each cell to be determined corresponds to one second failure cause value, or a plurality of cells to be determined correspond to the same second failure cause value. The specific correspondence is the same as the correspondence between the candidate target cell and the first failure cause value. For details, reference may be made to the description of the correspondence between the candidate target cell and the first failure cause value, and the details will not be repeated here.

[0093] Optionally, in this embodiment of the present application, the MRO-related information further includes first information. The first information includes one or more of the following information, namely, information about the source cell, information about the candidate target cell, first time information corresponding to each of at least one candidate target cell, information about the cell to be determined, and second time information corresponding to each of at least one cell to be determined. The information about the source cell includes the cell identity information of the source cell and / or the cell signal quality information of the source cell. The information about the candidate target cell includes the cell identity information of the candidate target cell and / or the cell signal quality information of the candidate target cell. The information about the cell to be determined includes the cell identity information of the cell to be determined and / or the cell signal quality information of the cell to be determined. Specifically, the cell identity information may include the PCI and frequency information corresponding to the cell, and / or the cell global identity. For example, the PCI and frequency information corresponding to the cell may be used as the identity of the cell, or the CGI may be used as the identity of the cell. The frequency information includes one or more of the absolute frequency of the synchronization signal block (such as absoluteFrequencySSB), the absolute frequency position of the reference resource module (such as common RB0) (such as absoluteFrequencyPointA), the frequency bandwidth list (such as frequencyBandList), the subcarrier spacing (such as subcarrier spacing, SCS), and the SCS-specific carrier list (such as scs-SpecificCarrierList). The cell signal quality information includes the reference signal received power (RSRP) of the cell and / or the reference signal received quality (RSRQ) of the cell. Optionally, the cell signal quality information may further include the signal quality change rate of the cell.

[0094] Optionally, in this embodiment of the present application, the first time information relates to the time interval from the time when the terminal device receives the conditional handover configuration information to the time when the terminal device triggers a handover to the first candidate target cell, the time interval from the time when the terminal device triggers a handover to the first candidate target cell to the time when the terminal device fails to access the first candidate target cell, and the time interval from the time when the terminal device fails to access the first candidate target cell to the time when the terminal device transmits the first failure cause value corresponding to the first candidate target cell (or the time interval from the time when the terminal device fails to access the first candidate target cell to the time when the terminal device transmits the first information). The first candidate target cell is any one of at least one candidate target cell.

[0095] It should be noted that, in this embodiment of the present application, the time when triggering a handover to the first candidate target cell means the time when the terminal device determines that the first candidate target cell meets the handover trigger condition, or the time when triggering a handover to the first candidate target cell means the time when the terminal device starts to access the first candidate target cell. The access can be a non - contention access or a contention access. For example, the time when triggering a handover to the first candidate target cell means the time when the terminal device starts a random access to the first candidate target cell, for example, the time when the terminal device transmits a preamble sequence to the first candidate target cell.

[0096] Alternatively, in a possible embodiment, the first time information includes information regarding the time interval from the time when the terminal device receives the conditional handover configuration information to the time when the terminal device triggers a handover to the first candidate target cell, and information regarding the time interval from the time when the terminal device triggers a handover to the first candidate target cell to the time when the terminal device transmits the first failure cause value corresponding to the first candidate target cell (or information regarding the time interval from the time when the terminal device triggers a handover to the first candidate target cell to the time when the terminal device transmits the first information). Alternatively, in another possible embodiment, the first time information includes information regarding the time interval from the time when the terminal device receives the conditional handover configuration information to the time when the terminal device fails to access the first candidate target cell, and information regarding the time interval from the time when the terminal device fails to access the first candidate target cell to the time when the terminal device transmits the first failure cause value corresponding to the first candidate target cell (or information regarding the time interval from the time when the terminal device fails to access the first candidate target cell to the time when the terminal device transmits the first information).

[0097] Alternatively, in yet another possible embodiment, the first time information is information regarding the time interval from the time when the terminal device receives the conditional handover configuration information to the time when the terminal device transmits the first failure cause value corresponding to the first candidate target cell, or information regarding the time interval from the time when the terminal device receives the conditional handover configuration information to the time when the terminal device transmits the first information.

[0098] Optionally, in this embodiment of the present application, the second time information includes information on the time interval from the time when the terminal device receives the conditional handover configuration information to the time when the terminal device determines that the first target cell does not meet the handover trigger condition, and information on the time interval from the time when the terminal device determines that the first target cell does not meet the handover trigger condition to the time when the terminal device transmits the second failure cause value corresponding to the first target cell (or information on the time interval from the time when the terminal device determines that the first target cell does not meet the handover trigger condition to the time when the terminal device transmits the first information). The first target cell is any one of at least one target cell.

[0099] Alternatively, in another possible embodiment, the second time information includes information on the time interval from the time when the terminal device receives the conditional handover configuration information to the time when the terminal device stops determining whether the first target cell meets the handover trigger condition, and information on the time interval from the time when the terminal device stops determining whether the first target cell meets the handover trigger condition to the time when the terminal device transmits the second failure cause value corresponding to the first target cell (or information on the time interval from the time when the terminal device stops determining whether the first target cell meets the handover trigger condition to the time when the terminal device transmits the first information). For example, the time when the terminal device stops determining whether the first target cell meets the handover trigger condition within the second time information is the time when the terminal device stops repeatedly determining whether the first target cell meets the handover trigger condition when determining "by polling".

[0100] Alternatively, in yet another possible embodiment, the second time information is information regarding the time interval from the time when the terminal device receives the conditional handover configuration information to the time when the terminal device transmits the second failure cause value corresponding to the first determination target cell, or the second time information is information regarding the time interval from the time when the terminal device receives the conditional handover configuration information to the time when the terminal device transmits the first information.

[0101] Optionally, in this embodiment of the present application, the first information may further include information about the cell currently being normally accessed by the terminal device after receiving the conditional handover configuration information, that is, information about the cell that will finally provide services to the terminal device in this CHO procedure. Alternatively, when understood in a different way, the information about the normally accessed cell is information about the cell that will finally hold (or establish or maintain) the RRC connection with the terminal device in this CHO procedure. The information about the cell includes cell identity information and / or cell signal quality information. For the description of the cell identity information and the cell signal quality information, reference may be made to the cell identity information and the cell signal quality information described above, and the details are not repeated here. For example, if the source cell is cell A, and two candidate cells, namely cell B and cell C, are configured in the conditional handover configuration information, and the terminal device determines based on the conditional handover configuration information that cell C meets the handover trigger condition and the terminal device successfully accesses cell C, the terminal device may record the information about cell C. Alternatively, in another example, the terminal device may start a re-establishment procedure, and if the re-establishment is successful, the terminal device may record the information about the cell to which the RRC connection has been re-established (for example, if the terminal device starts a procedure to re-establish the RRC connection with cell E and the RRC connection with cell E is successfully re-established, the terminal device may record the information about cell E). The cell to which the RRC connection is re-established may be one of the M candidate cells or a cell other than the M candidate cells. When the terminal device determines that none of the configured M candidate cells meet the handover trigger condition based on the currently received conditional handover configuration information, or when the terminal device fails to access all the candidate target cells among the configured M candidate cells, or when another situation occurs, the re-establishment procedure is started.Alternatively, in another example, the terminal device determines that none of the configured M candidate cells meet the handover trigger condition based on the currently received conditional handover configuration information, or the terminal device fails to access all candidate target cells among the configured M candidate cells, or another situation occurs, in which case the signal quality of the source cell is still relatively good, and the RRC connection between the terminal device and the source cell (or source network device) is still maintained. Therefore, the terminal device may record information about the source cell, i.e., the terminal device may record information about cell A.

[0102] Generally, a cell includes a downlink carrier and an uplink carrier. However, when a 5G new radio (NR) communication system deploys high-band cells, due to the relatively high NR operating band and relatively low transmission power of the terminal device, the terminal device located at the edge of the cell can receive signals from the network device (such as a base station), but the network device cannot receive signals from the terminal device. That is, the uplink coverage and the downlink coverage are asymmetric. To solve this problem, another low band (such as an LTE band) is introduced to assist the terminal device in uplink transmission. Specifically, a supplementary uplink (SUL) is introduced. Therefore, the terminal device is provided with two uplink (UL) carrier spectral bands for uplink transmission. A cell supporting the SUL configuration is provided with one downlink carrier and two uplink carriers. To distinguish the two uplink carriers, one is called the SUL carrier and the other is called the normal uplink (NUL) carrier. Optionally, in this embodiment of the present application, when a candidate target cell supports the SUL configuration, when the terminal device fails to access the candidate target cell supporting the SUL configuration, the first information may further include the UL carrier information (such as NUL or SUL) used by the terminal device when the terminal device fails to access the candidate target cell, in order to indicate whether the terminal device has failed to access the NUL or SUL of the candidate target cell. Alternatively, the terminal device may skip explicitly transmitting the carrier information. For example, the protocol may stipulate that when the terminal device does not transmit the carrier information, it is defaulted that the terminal device has failed to access the NUL of the candidate target cell or has failed to access the SUL of the candidate target cell. This is not particularly limited in this application.

[0103] Optionally, in this embodiment of the present application, the MRO-related information further includes second information. The second information is information about the cell when the terminal device successfully performs a conditional handover. The second information includes the following information, that is, information about the first target cell, and one or more of the third cause value and the third time information corresponding to the first target cell. The first target cell is a cell that satisfies the handover trigger condition among the candidate cells and is successfully accessed by the terminal device. It should be noted that if the cell that finally provides services to the terminal device in this CHO procedure is a cell that satisfies the handover trigger condition among the candidate cells and is successfully accessed by the terminal device (or understood in a different way, the cell where the terminal device successfully performs a conditional handover in this CHO procedure), the information about the cell that finally provides services to the terminal device in this CHO procedure recorded by the terminal device is the same as the information about the first target cell in this CHO procedure recorded by the terminal device. To avoid storage overhead, the terminal device may record only one of the same two pieces of information, or understood in a different way, the second information may exclude the information about the first target cell, or the first information may exclude the information about the cell that finally provides services to the terminal device in this CHO procedure.

[0104] The third cause value corresponding to the first target cell indicates that the terminal device has successfully executed a conditional handover. The third time information relates to the time interval from when the terminal device receives the conditional handover configuration information to when the terminal device triggers a handover to the first target cell, the time interval from when the terminal device triggers a handover to the first target cell to when the terminal device successfully accesses the first target cell, and the time interval from when the terminal device successfully accesses the first target cell to when the terminal device transmits the third cause value corresponding to the first target cell (or the time interval from when the terminal device successfully accesses the first target cell to when the terminal device transmits the first information, or the time interval from when the terminal device successfully accesses the first target cell to when the terminal device transmits the second information).

[0105] In this embodiment of the present application, it should be noted that the time point at which the handover to the first target cell is triggered either means the time point at which the terminal device determines that the first target cell meets the handover trigger condition, or the time point at which the handover to the first target cell is triggered means the time point at which the terminal device starts accessing the first target cell. The access can be non-competitive access or competitive access. For example, the time point at which the handover to the first candidate target cell is triggered means the time point at which the terminal device starts a random access to the first candidate target cell, for example, the time point at which the terminal device transmits a preamble sequence to the first target cell.

[0106] Alternatively, in another possible embodiment, the third time information corresponding to the first target cell includes information regarding the time interval from the time when the terminal device receives the conditional handover configuration information to the time when the terminal device successfully accesses the first target cell, and information regarding the time interval from the time when the terminal device successfully accesses the first target cell to the time when the terminal device transmits the third cause value corresponding to the first target cell (or information regarding the time interval from the time when the terminal device successfully accesses the first target cell to the time when the terminal device transmits the first information, or information regarding the time interval from the time when the terminal device successfully accesses the first target cell to the time when the terminal device transmits the second information).

[0107] Alternatively, in another possible embodiment, the third time information corresponding to the first target cell includes information regarding the time interval from the time when the terminal device receives the conditional handover configuration information to the time when the terminal device triggers a handover to the first target cell, and information regarding the time interval from the time when the terminal device triggers a handover to the first target cell to the time when the terminal device transmits the third cause value corresponding to the first target cell (or information regarding the time interval from the time when the terminal device triggers a handover to the first target cell to the time when the terminal device transmits the first information, or information regarding the time interval from the time when the terminal device successfully accesses the first target cell to the time when the terminal device transmits the second information). Alternatively, the third time information corresponding to the first target cell is information regarding the time interval from the time when the terminal device receives the conditional handover configuration information to the time when the terminal device transmits the third cause value corresponding to the first target cell (or the third time information corresponding to the first target cell includes information regarding the time interval from the time when the terminal device receives the conditional handover configuration information to the time when the terminal device transmits the first information, or information regarding the time interval from the time when the terminal device successfully accesses the first target cell to the time when the terminal device transmits the second information).

[0108] Optionally, in this embodiment of the present application, the conditional handover mechanism may be used as an auxiliary technique for the conventional handover mechanism. In other words, the source network device (i.e., the first network device) transmits conditional handover configuration information to the terminal device when the source link is of relatively high quality. Subsequently, the source network device may further transmit a handover message to the terminal device according to the existing conventional handover mechanism (in this embodiment of the present application, the handover message transmitted to the terminal device according to the conventional handover mechanism may be referred to as a conventional handover message). The conventional handover message in the NR system may be an RRC reconfiguration message including a reconfiguration information element with synchronization, or the conventional handover message in the LTE system may be an RRC connection reconfiguration message including a mobility control information element. This is not particularly limited in this embodiment of the present application. The conventional handover message includes information about the second target cell. For example, the information about the second target cell includes cell identity information of the second target cell, the C-RNTI assigned to the terminal device by the second target cell, and the random access configuration associated with the second target cell. The conventional handover message may be an RRC reconfiguration message carrying a reconfiguration information element with synchronization, or an RRC connection reconfiguration message carrying a mobility control information element. This is not particularly limited in the present application.

[0109] When a conditional handover mechanism is used as an auxiliary technology for a conventional handover mechanism, a possible scenario 1 is that after receiving conditional handover configuration information, the terminal device determines whether the candidate cell meets the handover trigger condition, and before a cell that meets the handover trigger condition is determined, or before the terminal device successfully accesses the cell that meets the determined handover trigger condition, if the terminal receives a conventional handover message, the terminal device may attempt to access the second target cell according to the conventional handover message. If the terminal device successfully accesses the second target cell, optionally, the terminal device may discard or delete the conditional handover configuration information. If the terminal device fails to access the second target cell, the terminal device may continue to perform the conditional handover according to the conditional handover configuration information.

[0110] When a conditional handover mechanism is used as an auxiliary technology for a conventional handover mechanism, another possible scenario 2 is that after receiving conditional handover configuration information, the terminal device determines a cell that meets the handover trigger condition and performs a normal handover to this cell. That is, before the terminal device normally hands over to a cell that meets the handover trigger condition, the source network device does not send a conventional handover message to the terminal device, or the source network device sends a conventional handover message to the terminal device, but the terminal device fails to receive the conventional handover message sent by the source network device. In this case, the terminal device may perform a conditional handover according to the conditional handover configuration information. A possible reason for the terminal device to fail to receive the conventional handover message is that the source link has relatively low quality. A possible reason for the source network device not to send a conventional handover message to the terminal device is that the preparation procedure for handover between the source network device and the network device to which the determined second target cell belongs fails or takes too long, so that the network is too late to configure the conventional handover procedure or fails to configure the conventional handover procedure. This is not particularly limited in this embodiment of the present application.

[0111] Optionally, in this embodiment of the present application, in possible scenario 1, if the terminal device receives a conventional handover message from the source network device but fails to access the second target cell indicated by the conventional handover message, the MRO-related information may further include third information. The third information is information regarding the failure of the handover, that is, in other words, information regarding the failure of the conventional handover. The third information may include one or more of information regarding the source cell, information regarding the second target cell, a fourth failure cause value, fourth time information, and first indication information. The first indication information indicates that the terminal device has received a handover message. The information regarding the second target cell includes the cell identity information of the second target cell and / or the cell signal quality information of the second target cell. The fourth failure cause value indicates that the terminal device has failed to execute a conventional handover or has failed to access the second target cell. For example, in order to indicate that the conventional handover has failed or the access to the second target cell has failed, the fourth failure cause value may be HOF, that is, the existing failure cause value HOF is reused. This is not particularly limited in the present application. The fourth time information includes information regarding the time interval from the time when the terminal device receives the handover message to the time when the terminal device fails to access the second target cell, and information regarding the time interval from the time when the terminal device fails to access the second target cell to the time when the terminal device transmits the third information. Alternatively, the fourth time information includes information regarding the time interval from the time when the terminal device receives the handover message to the time when the terminal device transmits the third information. The first indication information may be a binary value. For example, "1" means that the terminal device has received a handover message. Alternatively, the first indication information may be a boolean value. For example, "TRUE" means that the terminal device has received a handover message. Alternatively, the first indication information may be an information element.For example, the information element may be an instruction to receive a conventional handover message (such as HO-received), or the information element may be expressed or named in other forms. This is not particularly limited in this embodiment of the present application. When the terminal device reports the information element, it indicates that the terminal device has received a conventional handover message. If the terminal device does not report the information element, it indicates that the terminal device has not received a conventional handover message. The present application does not particularly limit the expression form of the first instruction information. Since the terminal device fails to perform a conventional handover according to the conventional handover message, the terminal device can continue to determine whether the candidate cell satisfies the handover trigger condition based on the conditional handover configuration information received before the handover message. If there are a candidate target cell and / or a cell to be determined among the candidate cells, the terminal device may record and report information about the candidate target cell and / or the cell to be determined. For details, please refer to the foregoing description, and the details will not be repeated here.

[0112] Optionally, in this embodiment of the present application, in possible scenario 2, when the terminal device has not received a conventional handover message from the source network device, the MRO-related information may further include fourth information. The fourth information is information regarding the failure of handover, that is, in other words, information regarding the failure of conventional handover. The fourth information may include one or more of information regarding the source cell, fifth time information, and second indication information. The second indication information indicates that the terminal device has not received a handover message. The fifth time information includes information regarding the time interval from the time when RLF occurred between the terminal device and the source network device to the time when the terminal device transmits the fourth information. The second indication information may be a binary value. For example, "0" means that the terminal device has not received a handover message. Alternatively, the second indication information may be a boolean value. For example, "FALSE" means that the terminal device has not received a handover message. Alternatively, the second indication information may be an information element. For example, the information element may be an indication of non-receipt of a conventional handover message (such as HO-notreceived), or the information element may be expressed or named in other forms. This is not limited here. When the terminal device reports an information element, it indicates that the terminal device has not received a conventional handover message. When the terminal device does not report an information element, it indicates that the terminal device has received a conventional handover message. The present application does not particularly limit the expression form of the second indication information. Since the terminal device has not received a conventional handover message, the terminal device determines whether a candidate cell meets the handover trigger condition based on the received conditional handover configuration. If there are candidate target cells and / or cells to be determined among the candidate cells, the terminal device may record and report information regarding the candidate target cells and / or cells to be determined. For details, reference may be made to the foregoing description, and the details will not be repeated here.

[0113] Step S601:

[0114] Optionally, Message 1 may be an RRC reconfiguration message that carries a reconfiguration with sync information element, or Message 1 may be a newly defined RRC message. For example, Message 1 may be a conditional handover message, or Message 1 may be named in another format, or Message 1 may be an RRC connection reconfiguration message that carries a mobility control info information element. This is not particularly limited in this embodiment of the present application.

[0115] Optionally, in this embodiment of the present application, the information regarding each of the M candidate cells may include the following information, namely, cell identity (such as the physical cell identifier (PCI) and frequency information corresponding to the cell, and / or the cell global identity (CGI) corresponding to the candidate cell. For example, the PCI and frequency information corresponding to the cell may be used as the cell identity, or the CGI may be used as the cell identity), the cell radio network temporary identifier (C-RNTI) assigned to the terminal device by the candidate cell, and one or more of the random access channel (RACH) resources associated with the candidate cell. For example, the random access channel RACH resources may include dedicated random access resources and / or common random access resources. The dedicated random access resources include a preamble index and a first time-frequency resource. The common random access resources include a second time-frequency resource. The frequency information may include one or more of the absolute frequency of the synchronization signal block (such as absoluteFrequencySSB), the absolute frequency position of the reference resource module (such as common RB0) (such as absoluteFrequencyPointA), the frequency bandwidth list (such as frequencyBandList), the subcarrier spacing (such as SCS), and the scs-specific carrier list (such as scs-SpecificCarrierList).

[0116] In this embodiment of the present application, the handover trigger condition is used for the terminal device to determine whether a handover to any one of the M candidate cells can be triggered. Optionally, the conditional handover configuration information may have a plurality of possible configurations of the handover trigger condition.

[0117] For example, a possible configuration of the handover trigger condition is to configure event A3 as the handover trigger event and configure parameter Q for event A3. Therefore, when the signal quality of a certain cell among the M candidate cells is Q higher than the signal quality of the current serving cell of the terminal device, that cell satisfies the handover trigger condition. It can be seen that Q is a threshold value, and the unit of Q can be decibel (dB) or decibel-milliwatt (dBm). This is not particularly limited in this embodiment of the present application.

[0118] Alternatively, another possible configuration of the handover trigger condition is to configure event A5 as the handover trigger event and configure parameters K and L for event A5. Therefore, when the signal quality of a certain cell among the M candidate cells is higher than K and the signal quality of the current serving cell of the terminal device is lower than L, that cell satisfies the handover trigger condition. The current serving cell of the terminal device is the cell that provides service to the terminal device when the terminal device receives conditional handover configuration information. That is, the current serving cell of the terminal device is the source cell. It can be seen that both K and L are threshold values, and the units for measuring Q and L can be decibel (dB) or decibel-milliwatt (dBm). This is not particularly limited in this embodiment of the present application.

[0119] Optionally, the handover trigger conditions in this embodiment of the present application may correspond one-to-one to each of the M candidate cells. In other words, the network device may configure M handover trigger conditions, and the M handover trigger conditions correspond one-to-one to the M candidate cells. Alternatively, the network device may configure the same handover trigger condition for a plurality of candidate cells. This is not particularly limited in the present application. In one example, the source cell is cell A, and three candidate cells B, C, and D are configured in the conditional handover configuration information. A handover trigger condition 1 may be configured for cell B, a handover trigger condition 2 may be configured for cell C, a handover trigger condition 3 may be configured for cell D, or a handover trigger condition 4 may be configured for cells B and C, a handover trigger condition 5 may be configured for cell D, or the same handover trigger condition 6 may be configured for cells B, C, and D.

[0120] It should be noted that the configuration of the handover trigger conditions and the correspondence between the handover trigger conditions and the candidate cells are merely exemplary descriptions of the present application and are not particularly limited in the present application with respect to actual applications.

[0121] In this embodiment of the present application, when the terminal device determines whether a cell among the candidate cells satisfies the handover trigger condition, the determination may be performed by "polling" or may be "once only". The "polling" determination means that the terminal device repeatedly determines whether the candidate cell that has undergone the determination procedure satisfies the handover trigger condition. The "once only" determination means that the terminal device does not repeatedly determine whether the candidate cell that has undergone the determination procedure satisfies the handover trigger condition. In the "polling" determination, the total period during which the terminal device determines whether the candidate cell satisfies the handover trigger condition may be specified by the protocol or may be sent to the terminal device by the network device (for example, message 1 sent to the terminal device by the first network device may include information regarding the total period, which is not particularly limited in the present application). Of course, optionally, the "polling" determination may be performed without a time limit. For example, candidate cells B and C are configured in the conditional handover configuration information. If the terminal device determines that cell B does not satisfy the handover trigger condition and subsequently the terminal device can continue to determine whether cell B satisfies the handover trigger condition, the determination is "polling". If the terminal device once determines that cell B does not satisfy the handover trigger condition and then the terminal device stops determining whether cell B satisfies the handover trigger condition, the determination is "once only".

[0122] In addition, when the terminal device determines whether a cell among the candidate cells satisfies the handover trigger condition based on the conditional handover configuration information, if the terminal device fails to access a cell that satisfies the handover trigger condition among the configured candidate cells, or if the terminal device determines that a cell among the candidate cells does not satisfy the handover trigger condition, the terminal device determines a cell that satisfies the handover trigger condition and until it can successfully access the cell that satisfies the handover trigger condition (in this case, the entire foregoing procedure may be regarded as a CHO procedure), or until all candidate cells have been determined by the terminal device as to whether any candidate cell satisfies the handover trigger condition, that is, until all candidate cells have undergone at least one attempt at determination by the terminal device as to whether any cell satisfies the handover trigger condition (in this case, the terminal device may perform the determination in a "polling" or "one-shot" manner, which is not particularly limited in this application) (in this case, the entire foregoing procedure may be regarded as a CHO procedure), the terminal device may continue to determine whether any cell among the candidate cells satisfies the handover trigger condition (in this case, the terminal device may perform the determination in a "polling" or "one-shot" manner, which is not particularly limited in this application). In this CHO procedure, it is possible that none of the candidate cells satisfy the handover trigger condition, or that the terminal device fails to access all cells that satisfy the handover trigger condition among the candidate cells. In one example, candidate cell B, candidate cell C, and candidate cell D are configured in the conditional handover configuration information, and the terminal device performs the determination in a "one-shot" manner. If the terminal device initially determines that cell B does not satisfy the handover trigger condition, or if cell B satisfies the handover trigger condition but the terminal device fails to access cell B, the terminal device may continue to determine whether the remaining candidate cells (such as cell C or cell D) satisfy the handover trigger condition.When the terminal device determines that cell D meets the handover trigger condition and the terminal device successfully accesses cell D, the terminal device stops determining whether cell C meets the handover trigger condition. Alternatively, in one example, candidate cell B, candidate cell C, and candidate cell D are configured in the conditional handover configuration information. When the terminal device first determines that cell B does not meet the handover trigger condition, or cell B meets the handover trigger condition but the terminal device fails to access cell B, the terminal device may continue to determine whether the remaining candidate cells (such as cell C or cell D) meet the handover trigger condition. When the terminal device determines that cell D meets the handover trigger condition but the terminal device fails to access cell D, or cell D does not meet the handover trigger condition, the terminal device continues to determine whether cell C meets the handover trigger condition.

[0123] Alternatively, in a possible embodiment, when the terminal device determines whether a cell among the candidate cells satisfies the handover trigger condition based on the conditional handover configuration information, the determination is performed up to N times, where N may be specified by the protocol or may be sent to the terminal device by the network device (for example, message 1 sent to the terminal device by the first network device may include the value of N, and N is an integer greater than or equal to 1). In this embodiment, if the terminal device fails to access a cell that satisfies the handover trigger condition among the configured candidate cells, or if the terminal device determines that a cell among the candidate cells does not satisfy the handover trigger condition, the terminal device may continue to perform subsequent determinations, that is, may continue to determine whether any of the candidate cells satisfies the handover trigger condition (in this case, the terminal device may perform the determination in a "polling" or "one-shot" manner, which is not particularly limited in this application). The terminal device either (1) does not abort the determination until the total number of determinations by the terminal device reaches N, or (2) before the number of determinations reaches N, the terminal device determines a cell that satisfies the handover trigger condition and successfully accesses the cell that satisfies the handover trigger condition. When the determination is performed N times, the terminal device aborts the determination. The entire foregoing procedure may be regarded as a CHO procedure. Alternatively, the total number of determinations by the terminal device does not reach N, and before the number of determinations reaches N, the terminal device determines a cell that satisfies the handover trigger condition and successfully accesses the cell that satisfies the handover trigger condition. Therefore, the terminal device aborts the determination. The entire foregoing procedure may be regarded as a CHO procedure. In one example, candidate cell B, candidate cell C, and candidate cell D are configured in the conditional handover configuration information, N is 2, and the terminal device performs the determination in a "one-shot" manner. If the terminal device initially determines that cell B does not satisfy the handover trigger condition, or if cell B satisfies the handover trigger condition but the terminal device fails to access cell B, the terminal device may continue to determine whether the remaining candidate cells (such as cell C or cell D) satisfy the handover trigger condition.If the terminal device determines that cell C meets the handover trigger condition, but the terminal device fails to access cell C, or cell C does not meet the handover trigger condition, the terminal device stops determining whether cell D meets the handover trigger condition. Alternatively, if the terminal device first determines that cell B meets the handover trigger condition and the terminal device successfully accesses cell B, even if N has not reached 2 and is equal to 1, the terminal device stops determining whether cell C or cell D meets the handover trigger condition.

[0124] Alternatively, in another possible embodiment, when the terminal device determines whether a cell among the candidate cells satisfies the handover trigger condition based on the conditional handover configuration information, a maximum of R random access attempts are performed. The random access attempt means that when the terminal device determines that a candidate cell satisfies the handover trigger condition based on the conditional handover configuration information, the terminal device performs a random access to the cell in order to attempt to access the cell. For example, the terminal device has an opportunity for a maximum of R random access attempts. All candidate cells are subject to the determination by the terminal device, and the terminal device continues to determine until none of the candidate cells satisfies the handover trigger condition, or until the terminal device starts all R random access attempts, or until the terminal device has not completed all R random access attempts but has successfully accessed a cell that satisfies the handover trigger condition. R may be specified by the protocol or may be sent to the terminal device by the network device. For example, message 1 sent to the terminal device by the first network device may include the value of R, and R is an integer greater than or equal to 1. This is not particularly limited in this embodiment of the present application. In this embodiment, if the terminal device fails to access a cell that satisfies the handover trigger condition among the configured candidate cells, or if the terminal device determines that a cell among the candidate cells does not satisfy the handover trigger condition, the terminal device may continue to perform subsequent determinations, that is, may continue to determine whether any of the candidate cells satisfies the handover trigger condition (in this case, the terminal device may perform the determination in a "polling" or "one-shot" manner, which is not particularly limited in the present application).The terminal device does not abort the determination, or does not end this CHO procedure, until the total number of random access attempts initiated by the terminal device reaches R, or (2) before the total number of random access attempts reaches R, the terminal device determines a cell that satisfies the handover trigger condition and successfully accesses the cell that satisfies the handover trigger condition, or (3) none of the configured candidate cells satisfy the handover trigger condition. When all R random access attempts are completed, the terminal device aborts the determination. The entire foregoing procedure may be regarded as a CHO procedure. Alternatively, the total number of random access attempts initiated by the terminal device does not reach R, and before the number of random access attempts reaches R, the terminal device determines a cell that satisfies the handover trigger condition and successfully accesses the cell that satisfies the handover trigger condition. Therefore, the terminal device aborts the determination. The entire foregoing procedure may be regarded as a CHO procedure. Alternatively, the terminal device determines that none of the candidate cells configured by the network device satisfy the handover trigger condition, the total number of random access attempts initiated by the terminal device is equal to 0, and therefore, the total number of random access attempts does not reach R, but the terminal device aborts the determination. The entire foregoing procedure may be regarded as a CHO procedure. In one example, candidate cell B, candidate cell C, and candidate cell D are configured in the conditional handover configuration information, R is 2, and the terminal device executes the determination in a "one-time only" manner. If the terminal device initially determines that cell B satisfies the handover trigger condition but fails to access cell B, the terminal device may continue to determine whether the remaining candidate cells (such as cell C or cell D) satisfy the handover trigger condition. If the terminal device determines that cell C satisfies the handover trigger condition but fails to access cell C, the terminal device aborts the determination. In this case, R = 2 and this CHO procedure ends. Alternatively, if the terminal device initially determines that cell B satisfies the handover trigger condition and the terminal device successfully accesses cell B, even if R has not reached 2 and is equal to 1, the terminal device aborts the determination and this CHO procedure ends.Alternatively, if the terminal device determines that none of the candidate cells B, candidate cell C, and candidate cell D satisfy the handover trigger condition, the terminal device aborts the determination. In this case, R = 0, and this CHO procedure ends.

[0125] Alternatively, in another possible embodiment, when the terminal device determines whether a cell among the candidate cells meets the handover trigger condition based on the conditional handover configuration information, the determination is made only within a period H after the reception of the conditional handover configuration information, where H may be specified by the protocol or may be sent by the network device to the terminal device (e.g., message 1 sent by the first network device to the terminal device may include the value of H). In this embodiment, if the terminal device fails to access a cell that meets the handover trigger condition among the configured candidate cells, or if the terminal device determines that a cell among the candidate cells does not meet the handover trigger condition, the terminal device may continue to perform subsequent determinations within the period H after the reception of the conditional handover configuration information to determine whether any of the candidate cells meets the handover trigger condition (in this case, the terminal device may perform the determination in a "polling" or "one-shot" manner, which is not particularly limited in this application). The terminal device does not stop the determination until timeout, or before timeout, the terminal device determines a cell that meets the handover trigger condition and successfully accesses the cell that meets the handover trigger condition. The entire foregoing procedure may be regarded as a CHO procedure. In one example, candidate cell B, candidate cell C, and candidate cell D are configured in the conditional handover configuration information, H is 100 seconds, and the terminal device performs the determination in a "one-shot" manner. If the terminal device initially determines that cell B does not meet the handover trigger condition, or if cell B meets the handover trigger condition but the terminal device fails to access cell B, the terminal device may continue to determine whether the remaining candidate cells (such as cell C or cell D) meet the handover trigger condition within the remaining time. When a timeout occurs, or before timeout, if the terminal device determines a cell that meets the handover trigger condition and successfully accesses the cell that meets the handover trigger condition, the terminal device stops the determination.

[0126] In any of the above-described possible embodiments where the terminal device determines whether a candidate cell meets the handover trigger condition at random, the order determined by the terminal device may be regular. For example, the network device may specify the order in which to determine for candidate cells. Alternatively, the network device may specify the priority of each candidate cell, and the terminal device executes the determination for the candidate cells according to the priority. Alternatively, the protocol defines the order in which the terminal device executes the determination for the candidate cells. Alternatively, the order determined by the terminal device may be irregular. For example, the order of determination depends on the implementation of the terminal device. This is not particularly limited in this embodiment of the present application.

[0127] In the following, the MRO information recorded by the terminal device in step S602 will be described as an example. Specifically, the MRO-related information recorded by the terminal device in different scenarios will be described in detail below using examples. In this example, the source cell is cell A, and two candidate cells, namely cell B and cell C, are configured in the conditional handover configuration information. When the terminal device fails to access a cell that meets the handover trigger condition among the configured candidate cells, or when the terminal device determines that a cell among the candidate cells does not meet the handover trigger condition, the terminal device determines a cell that meets the handover trigger condition and continues to determine whether any of the candidate cells meets the handover trigger condition until the terminal device can normally access the cell that meets the handover trigger condition or until all candidate cells have received a determination by the terminal device regarding whether any of the candidate cells meets the handover trigger condition.

[0128] The conditional handover procedure may have two preconditions, namely, Precondition 1: After receiving the conditional handover configuration information, the terminal device may maintain data transmission with the source cell until the terminal device successfully accesses the target cell or until RLF occurs in the source cell, or Precondition 2: The terminal device disconnects data transmission with the source cell immediately after receiving the conditional handover configuration information. It should be noted that in the following different scenarios, the connection state of the terminal device under the two preconditions of the CHO procedure will be described.

[0129] Scenario I: Cell B is a candidate target cell and Cell C is a cell to be judged. The terminal device fails to access Cell B.

[0130] Optionally, in this scenario, the terminal device may determine, based on the conditional handover configuration information, that Cell B meets the handover trigger condition. Therefore, a random access procedure is executed by the terminal device for Cell B, but the random access procedure by the terminal device for Cell B fails, or RLF occurs in Cell B after the terminal device successfully accesses Cell B. In addition, the terminal device determines, based on the conditional handover configuration information, that Cell C does not meet the handover trigger condition.

[0131] In Scenario I, in this CHO procedure executed by the terminal device based on the currently received conditional handover configuration information, since the terminal device fails to access Cell B and Cell C does not meet the handover trigger condition, the cell that finally provides services to the terminal device in this CHO procedure (or, if understood in a different way, the cell that finally maintains (or establishes or maintains) the RRC connection with the terminal device in this CHO procedure) may fall into any of the following four situations.

[0132] (1) Under precondition 1, if the terminal device fails to access cell B, cell C is determined not to meet the handover trigger condition, and RLF occurs between the terminal device and source cell A (for example, the signal quality of source cell A deteriorates), the terminal device starts a re-establishment procedure to re-establish an RRC connection with a selected appropriate new cell D (such as a cell meeting the S criterion).

[0133] (2) Under precondition 2, if the terminal device fails to access cell B and cell C is determined not to meet the handover trigger condition, the terminal device starts a re-establishment procedure to re-establish an RRC connection with a selected appropriate new cell D (such as a cell meeting the S criterion).

[0134] (3) Under precondition 1, if the terminal device fails to access cell B, cell C is determined not to meet the handover trigger condition, and source cell A has relatively high signal quality, RLF does not occur between the terminal device and source cell A, that is, the RRC connection between the terminal device and source cell A (or source network device) is still maintained.

[0135] (4) Under precondition 2, if the terminal device fails to access cell B and cell C is determined not to meet the handover trigger condition, the terminal device starts a re-establishment procedure where the selected appropriate cell is source cell A. Therefore, the terminal device executes an RRC re-establishment procedure with source cell A.

[0136] It should be noted that in this embodiment of the present application, the appropriate new cell D selected by the terminal device may be the same as source cell A or may be different from source cell A. This is not particularly limited in the present application. In addition, the appropriate new cell D selected by the terminal device may be the same as a candidate cell (such as cell B or cell C) or may be different from the candidate cell. This is not particularly limited in the present application.

[0137] In situation (1) of Scenario I, the MRO-related information recorded by the terminal device includes a first failure cause value corresponding to cell B and a second failure cause value corresponding to cell C. For the description of the first failure cause value, reference may be made to the description of the first failure cause value in the foregoing embodiment, and for the description of the second failure cause value, reference may be made to the description of the second failure cause value in the foregoing embodiment, and the details are not repeated here.

[0138] Optionally, in situation (1) of Scenario I, the MRO-related information recorded by the terminal device may further include one or more of the following items, namely, information about the source cell, information about the candidate target cell, first time information corresponding to each of at least one candidate target cell, information about the cell to be determined, second time information corresponding to each of at least one cell to be determined, information about the cell that finally provides services to the terminal device in this CHO procedure (or, if understood in a different way, the cell that finally maintains (or establishes or maintains) the RRC connection with the terminal device in this CHO procedure), and UL carrier information of the candidate target cell in the first information. Specifically, in situation (1) of Scenario I, the source cell is cell A, the candidate target cell is cell B, the cell to be determined is cell C, and the cell that finally provides services to the terminal device (or, if understood in another way, the cell that finally maintains (or establishes) the RRC connection with the terminal device in this CHO procedure) is cell D. For a detailed description of the relevant information, reference may be made to the description of the corresponding information in the foregoing embodiment, and the details are not repeated here.

[0139] In situation (2) of Scenario I, the cell that finally provides services to the terminal device (or, if understood in a different way, the cell that finally maintains (or establishes) the RRC connection with the terminal device in this CHO procedure) is cell D. The MRO-related information recorded by the terminal device is the same as the MRO-related information recorded in situation (1) of Scenario I. For the relevant description, reference may be made to the description of situation (1) of Scenario I, and the details are not repeated here.

[0140] In the situation (3) of Scenario I, the cell that finally provides services to the terminal device (or, if understood in a different way, the cell that finally maintains (or sustains) the RRC connection with the terminal device in this CHO procedure) is Cell A. The MRO information recorded by the terminal device is the same as the MRO-related information recorded in the situation (1) of Scenario I. However, in the situation (3) of Scenario I, the difference is that the recorded information regarding the cell that finally provides services to the terminal device in this CHO procedure is the information regarding the source cell A rather than the information regarding Cell D. For relevant explanations, reference may be made to the description of the situation (1) of Scenario I, where details will not be repeated here.

[0141] In the situation (4) of Scenario I, the cell that finally provides services to the terminal device (or, if understood in a different way, the cell that finally maintains (or establishes) the RRC connection with the terminal device in this CHO procedure) is Cell A. The MRO information recorded by the terminal device is the same as the MRO-related information recorded in the situation (3) of Scenario I. For relevant explanations, reference may be made to the description of the situation (3) of Scenario I, where details will not be repeated here.

[0142] Scenario II: Cell B is the candidate target cell. The terminal device fails to access Cell B but can access Cell C normally.

[0143] Optionally, in this scenario, the terminal device determines that cell B meets the handover trigger condition based on the conditional handover configuration information. Accordingly, the terminal device executes a random access procedure for cell B, but the random access procedure by the terminal device for cell B fails, or an RLF occurs in cell B after the terminal device successfully accesses cell B. In addition, the terminal device determines that cell C meets the handover trigger condition based on the conditional handover configuration information. Accordingly, the terminal device executes a random access procedure for cell C, and the random access procedure by the terminal device for cell C is successful, whereby the terminal device successfully hands over to cell C.

[0144] In Scenario II, the MRO-related information recorded by the terminal device includes a first failure cause value corresponding to cell B. For the description of the first failure cause value, reference may be made to the description of the first failure cause value in the foregoing embodiments, and details are not repeated here.

[0145] Optionally, in Scenario II, the MRO-related information recorded by the terminal device may further include one or more of the following items in the first information, namely, information about the source cell, information about the candidate target cell, the first time information corresponding to each of at least one candidate target cell, information about the cell that finally provides services to the terminal device in this CHO procedure (or, if understood in a different way, the cell that finally maintains (or establishes or maintains) the RRC connection with the terminal device in this CHO procedure), and UL carrier information of the candidate target cell. Specifically, in Scenario II, the source cell is cell A, at least one candidate target cell includes cell B, and the cell that finally provides services to the terminal device in this CHO procedure (or, if understood in another way, the cell that finally maintains (or establishes) the RRC connection with the terminal device in this CHO procedure) is cell C. For a detailed description of the relevant information, reference may be made to the description of the corresponding information in the foregoing embodiments, and details are not repeated here.

[0146] Scenario III: Cells B and C are candidate target cells. The terminal device fails to access Cells B and C.

[0147] Optionally, in this scenario, the terminal device determines, based on the conditional handover configuration information, that Cell B meets the handover trigger condition. Therefore, a random access procedure is executed by the terminal device for Cell B, but the random access procedure by the terminal device for Cell B fails, or an RLF occurs in Cell B after the terminal device successfully accesses Cell B. In addition, the terminal device determines, based on the conditional handover configuration information, that Cell C meets the handover trigger condition. Therefore, a random access procedure is executed by the terminal device for Cell C, but the random access procedure by the terminal device for Cell C fails, or an RLF occurs in Cell C after the terminal device successfully accesses Cell C.

[0148] In Scenario III, in this CHO procedure executed by the terminal device based on the currently received conditional handover configuration information, since the terminal device fails to access Cells B and C, the cell that finally provides service to the terminal device in this CHO procedure (or, if understood differently, the cell that is determined by the terminal device to finally maintain (or establish or sustain) the RRC connection with the terminal device in this CHO procedure) may fall into any of the following four situations.

[0149] (1) Under Premise 1, if the terminal device fails to access Cell B, fails to access Cell C, and an RLF occurs between the terminal device and the source cell A (for example, the signal quality of the source cell A deteriorates), the terminal device starts a re-establishment procedure to re-establish an RRC connection with a selected appropriate new cell D (such as a cell that meets the S criterion).

[0150] (2) Under precondition 2, if the terminal device fails to access cell B and fails to access cell C, the terminal device starts a reestablishment procedure to reestablish an RRC connection with a selected appropriate new cell D (such as a cell that meets the S criterion).

[0151] (3) Under precondition 1, if the terminal device fails to access cell B and fails to access cell C, and the source cell A has relatively high signal quality, no RLF occurs between the terminal device and the source cell A, that is, the RRC connection between the terminal device and the source cell A (or the source network device) is still maintained.

[0152] (4) Under precondition 2, if the terminal device fails to access cell B and fails to access cell C, the terminal device starts a reestablishment procedure where the selected appropriate cell is the source cell A. Therefore, the terminal device executes an RRC reestablishment procedure with the source cell A.

[0153] In situation (1) of Scenario III, the MRO-related information recorded by the terminal device includes a first failure cause value corresponding to cell B and a first failure cause value corresponding to cell C. For the related description of the first failure cause value, reference may be made to the description of the first failure cause value in the foregoing embodiments, and the details are not repeated here.

[0154] Optionally, in Scenario III situation (1), the MRO-related information recorded by the terminal device may further include one or more of the following items in the first information, namely, information about the source cell, information about the candidate target cell, the first time information corresponding to each of at least one candidate target cell, information about the cell that finally provides services to the terminal device in this CHO procedure (or, if understood differently, the cell that finally maintains (or establishes or sustains) the RRC connection with the terminal device in this CHO procedure), and the UL carrier information of the candidate target cell. Specifically, in Scenario III situation (1), the source cell is cell A, the candidate target cells include cell B and cell C, and the cell that finally provides services to the terminal device in this CHO procedure (or, if understood differently, the cell that finally maintains (or establishes) the RRC connection with the terminal device in this CHO procedure) is cell D. For a detailed description of the relevant information, reference may be made to the description of the corresponding information in the foregoing embodiments, and the details are not repeated here.

[0155] In Scenario III situation (2), the cell that finally provides services to the terminal device (or, if understood differently, the cell that finally maintains (or establishes) the RRC connection with the terminal device in this CHO procedure) is cell D. The MRO-related information recorded by the terminal device is the same as the MRO-related information recorded in Scenario III situation (1). For relevant explanations, reference may be made to the description of Scenario III situation (1), and the details are not repeated here.

[0156] In the situation (3) of Scenario III, the cell that finally provides services to the terminal device (or, if understood in a different way, the cell that finally maintains (or sustains) the RRC connection with the terminal device in this CHO procedure) is Cell A. The MRO information recorded by the terminal device is the same as the MRO-related information recorded in the situation (1) of Scenario III. However, in the situation (3) of Scenario III, the difference is that the information recorded regarding the cell that finally provides services to the terminal device in this CHO procedure is information regarding the source cell A rather than information regarding Cell D. For related explanations, reference may be made to the explanation in the situation (1) of Scenario III, and the details will not be repeated here.

[0157] In the situation (4) of Scenario III, the cell that finally provides services to the terminal device (or, if understood in a different way, the cell that finally maintains (or establishes) the RRC connection with the terminal device in this CHO procedure) is Cell A. The MRO information recorded by the terminal device is the same as the MRO-related information recorded in the situation (3) of Scenario III. For related explanations, reference may be made to the explanation in the situation (3) of Scenario III, and the details will not be repeated here.

[0158] Scenario IV: Cells B and C are the cells to be determined. That is, neither Cell B nor Cell C satisfies the handover trigger condition.

[0159] Specifically, based on the conditional handover configuration information, the terminal device determines that Cell B does not satisfy the handover trigger condition and continues to determine whether Cell C satisfies the handover trigger condition. The terminal device determines that Cell C also does not satisfy the handover trigger condition.

[0160] In Scenario IV, in this CHO procedure executed by the terminal device based on the currently received conditional handover configuration information, since neither Cell B nor Cell C satisfies the handover trigger condition, the cell that finally provides services to the terminal device in this CHO procedure (or, if understood differently, the cell that finally maintains (or establishes or sustains) the RRC connection with the terminal device in this CHO procedure) may fall into any of the following four situations.

[0161] (1) Under Premise Condition 1, if the terminal device determines that Cell B does not satisfy the handover trigger condition and Cell C does not satisfy the handover trigger condition, and an RLF occurs between the terminal device and the source cell A (for example, the signal quality of the source cell A deteriorates), the terminal device starts a re-establishment procedure to re-establish an RRC connection with a selected appropriate new cell D (such as a cell that meets the S criterion).

[0162] (2) Under Premise Condition 2, if the terminal device determines that Cell B does not satisfy the handover trigger condition and Cell C does not satisfy the handover trigger condition, the terminal device starts a re-establishment procedure to re-establish an RRC connection with a selected appropriate new cell D (such as a cell that meets the S criterion).

[0163] (3) Under Premise Condition 1, if the terminal device determines that Cell B does not satisfy the handover trigger condition and Cell C does not satisfy the handover trigger condition, and the source cell A has relatively high signal quality, no RLF occurs between the terminal device and the source cell A, that is, the RRC connection between the terminal device and the source cell A (or the source network device) is still maintained.

[0164] (4) Under Premise Condition 2, if the terminal device determines that Cell B does not satisfy the handover trigger condition and Cell C does not satisfy the handover trigger condition, the terminal device starts a re-establishment procedure where the selected appropriate cell is the source cell A. Therefore, the terminal device executes an RRC re-establishment procedure with the source cell A.

[0165] In the situation (1) of Scenario IV, the MRO-related information recorded by the terminal device includes the second failure cause value corresponding to cell B and the second failure cause value corresponding to cell C. For the related description of the second failure cause value, reference may be made to the description of the second failure cause value in the foregoing embodiments, and the details are not repeated here.

[0166] Optionally, in the situation (1) of Scenario IV, the MRO-related information recorded by the terminal device may further include one or more of the following items, namely, information related to the source cell, information related to the cell to be determined, the second time information corresponding to each of at least one cell to be determined, and information related to the cell that finally provides services to the terminal device in this CHO procedure (or, when understood in a different way, the cell that finally maintains (or establishes or maintains) the RRC connection with the terminal device in this CHO procedure). Specifically, in the situation (1) of Scenario IV, the source cell is cell A, the cells to be determined include cell B and cell C, and the cell that finally provides services to the terminal device in this CHO procedure (or, when understood in a different way, the cell that finally maintains (or establishes) the RRC connection with the terminal device in this CHO procedure) is cell D. For the description of the related information, reference may be made to the description of the corresponding information in the foregoing embodiments, and the details are not repeated here.

[0167] In the situation (2) of Scenario IV, the cell that finally provides services to the terminal device (or, when understood in a different way, the cell that finally maintains (or establishes) the RRC connection with the terminal device in this CHO procedure) is cell D. The MRO-related information recorded by the terminal device is the same as the MRO-related information recorded in the situation (1) of Scenario IV. For the related description, reference may be made to the description of the situation (1) of Scenario IV, and the details are not repeated here.

[0168] In scenario IV, situation (3), the cell that ultimately provides services to the terminal device (or, if understood differently, the cell that ultimately maintains (or sustains) the RRC connection with the terminal device in this CHO procedure) is cell A. The MRO information recorded by the terminal device is the same as the MRO-related information recorded in scenario IV, situation (1). However, in scenario IV, situation (3), the difference is that the information recorded regarding the cell that ultimately provides services to the terminal device in this CHO procedure is information regarding source cell A, rather than information regarding cell D. For related explanations, reference may be made to the explanation in scenario IV, situation (1), and the details will not be repeated here.

[0169] In scenario IV, situation (4), the cell that ultimately provides services to the terminal device (or, if understood differently, the cell that ultimately maintains (or establishes) the RRC connection with the terminal device in this CHO procedure) is cell A. The MRO information recorded by the terminal device is the same as the MRO-related information recorded in scenario IV, situation (3). For related explanations, reference may be made to the explanation in scenario IV, situation (3), and the details will not be repeated here.

[0170] In the above four scenarios, if the terminal device fails to access a cell that meets the handover trigger condition among the configured candidate cells, or if the terminal device determines that the cells among the candidate cells do not meet the handover trigger condition, the terminal device determines a cell that meets the handover trigger condition and continues to determine whether any of the candidate cells meets the handover trigger condition until it successfully accesses the cell that meets the handover trigger condition or until all candidate cells have been determined by the terminal device regarding whether any of the candidate cells meets the handover trigger condition. In the following, an example is used to explain in detail the MRO-related information recorded by the terminal device in different scenarios. In this example, when the terminal device determines whether any of the candidate cells meets the handover trigger condition based on the conditional handover configuration information, the determination is executed up to N times at most. Specifically, N is 1, the source cell is cell A, and two candidate cells, namely candidate cell B and candidate cell C, are configured in the conditional handover configuration information.

[0171] It should be noted that when the terminal device executes the determination up to N times, the candidate cells can be randomly selected by the terminal device or according to a preset rule for determination. The preset rule may be specified in the protocol or configured by the network device. This is not particularly limited in this application.

[0172] Scenario V: Cell B is the candidate target cell. The terminal device fails to access cell B.

[0173] Specifically, the terminal device determines that cell B meets the handover trigger condition based on the conditional handover configuration information. Therefore, a random access procedure is executed by the terminal device for cell B, but the random access procedure by the terminal device for cell B fails, or an RLF occurs in cell B after the terminal device successfully accesses cell B. In this case, N is equal to 1, that is, since the terminal device performs a maximum of one determination, the terminal device stops determining whether cell C meets the handover trigger condition.

[0174] In scenario V, in this CHO procedure executed by the terminal device based on the currently received conditional handover configuration information, since the terminal device fails to access cell B after performing one determination, the cell that finally provides service to the terminal device in this CHO procedure (or, if understood differently, the cell that finally maintains (or establishes or sustains) the RRC connection with the terminal device in this CHO procedure) may fall into any of the following four situations.

[0175] (1) Under precondition 1, if the terminal device fails to access cell B and an RLF occurs between the terminal device and the source cell A (for example, the signal quality of the source cell A deteriorates), the terminal device starts a re-establishment procedure to re-establish an RRC connection with a selected appropriate new cell D (such as a cell that meets the S criterion).

[0176] (2) Under precondition 2, if the terminal device fails to access cell B, the terminal device starts a re-establishment procedure to re-establish an RRC connection with a selected appropriate new cell D (such as a cell that meets the S criterion).

[0177] (3) Under the premise condition 1, if the terminal device fails to access cell B and the source cell A has relatively high signal quality, RLF does not occur between the terminal device and the source cell A, that is, the RRC connection between the terminal device and the source cell A (or the source network device) is still maintained.

[0178] (4) Under the premise condition 2, if the terminal device fails to access cell B, the terminal device starts the re-establishment procedure where the selected appropriate cell is the source cell A. Therefore, the terminal device executes the RRC re-establishment procedure with the source cell A.

[0179] In the situation (1) of Scenario V, the MRO-related information recorded by the terminal device includes the first failure cause value corresponding to cell B. For the related description of the first failure cause value, reference can be made to the description of the first failure cause value in the foregoing embodiments, and the details are not repeated here.

[0180] Optionally, in the situation (1) of Scenario V, the MRO-related information recorded by the terminal device may further include one or more of the following items, that is, information related to the source cell, information related to the candidate target cell, the first time information corresponding to each of at least one candidate target cell, information related to the cell that finally provides services to the terminal device in this CHO procedure (or, when understood in a different way, the cell that finally maintains (or establishes or maintains) the RRC connection with the terminal device in this CHO procedure), and UL carrier information of the candidate target cell. Specifically, in the situation (1) of Scenario V, the source cell is cell A, at least one candidate target cell includes cell B, and the cell that finally provides services to the terminal device in this CHO procedure (or, when understood in another way, the cell that finally maintains (or establishes) the RRC connection with the terminal device in this CHO procedure) is cell D. For the description of the related information, reference can be made to the description of the corresponding information in the foregoing embodiments, and the details are not repeated here.

[0181] In the situation (2) of Scenario V, the cell that finally provides services to the terminal device (or, if understood differently, the cell that finally maintains (or establishes) the RRC connection with the terminal device in this CHO procedure) is Cell D. The MRO-related information recorded by the terminal device is the same as the MRO-related information recorded in the situation (1) of Scenario V. For related explanations, reference may be made to the explanation of the situation (1) of Scenario V, and the details will not be repeated here.

[0182] In the situation (3) of Scenario V, the cell that finally provides services to the terminal device (or, if understood differently, the cell that finally maintains (or sustains) the RRC connection with the terminal device in this CHO procedure) is Cell A. The MRO information recorded by the terminal device is similar to the MRO-related information recorded in the situation (1) of Scenario V. However, in the situation (3) of Scenario V, the difference is that the information recorded regarding the cell that finally provides services to the terminal device in this CHO procedure is information regarding source cell A rather than information regarding Cell D. For related explanations, reference may be made to the explanation of the situation (1) of Scenario V, and the details will not be repeated here.

[0183] In the situation (4) of Scenario V, the cell that finally provides services to the terminal device (or, if understood differently, the cell that finally maintains (or establishes) the RRC connection with the terminal device in this CHO procedure) is Cell A. The MRO information recorded by the terminal device is the same as the MRO-related information recorded in the situation (3) of Scenario V. For related explanations, reference may be made to the explanation of the situation (3) of Scenario V, and the details will not be repeated here.

[0184] Scenario VI: Cell B is the cell to be judged. That is, Cell B does not meet the handover trigger condition.

[0185] Specifically, the terminal device determines that cell B does not meet the handover trigger condition based on the conditional handover configuration information. In this case, N is equal to 1, that is, since the terminal device performs a maximum of one determination, the terminal device stops determining whether cell C meets the handover trigger condition.

[0186] In Scenario VI, in this CHO procedure executed by the terminal device based on the currently received conditional handover configuration information, after the terminal device performs one determination and determines that cell B does not meet the handover trigger condition, the cell that finally provides service to the terminal device in this CHO procedure (or, if understood differently, the cell that finally maintains (or establishes or sustains) the RRC connection with the terminal device in this CHO procedure) may fall into any of the following four situations. (1) Under Premise Condition 1, when cell B does not meet the handover trigger condition and RLF occurs between the terminal device and source cell A (for example, the signal quality of source cell A deteriorates), the terminal device starts a re-establishment procedure to re-establish an RRC connection with a selected appropriate new cell D (such as a cell that meets the S criterion).

[0187] (2) Under Premise Condition 2, when cell B does not meet the handover trigger condition, the terminal device starts a re-establishment procedure to re-establish an RRC connection with a selected appropriate new cell D (such as a cell that meets the S criterion).

[0188] (3) Under Premise Condition 1, when cell B does not meet the handover trigger condition and source cell A has relatively high signal quality, RLF does not occur between the terminal device and source cell A, that is, the RRC connection between the terminal device and source cell A (or source network device) is still maintained.

[0189] (4) Under prerequisite condition 2, if cell B does not meet the handover trigger condition, the terminal device starts a re-establishment procedure where the selected appropriate cell is the source cell A. Therefore, the terminal device executes an RRC re-establishment procedure with the source cell A.

[0190] In scenario VI situation (1), the MRO-related information recorded by the terminal device includes a second failure cause value corresponding to cell B. For the related description of the second failure cause value, reference may be made to the description of the second failure cause value in the foregoing embodiments, and the details are not repeated here.

[0191] Optionally, in scenario VI situation (1), the MRO-related information recorded by the terminal device may further include one or more of the following items in the first information, namely, information regarding the source cell, information regarding the cell to be determined, second time information corresponding to each of at least one cell to be determined, and information regarding the cell that finally provides services to the terminal device in this CHO procedure (or, when understood in a different way, the cell that finally maintains (or establishes or sustains) the RRC connection with the terminal device in this CHO procedure). Specifically, in scenario VI situation (1), the source cell is cell A, the cell to be determined is cell B, and the cell that finally provides services to the terminal device in this CHO procedure (or, when understood in a different way, the cell that finally maintains (or establishes) the RRC connection with the terminal device in this CHO procedure) is cell D. For the description of the related information, reference may be made to the description of the corresponding information in the foregoing embodiments, and the details are not repeated here.

[0192] In scenario VI situation (2), the cell that finally provides services to the terminal device (or, when understood in a different way, the cell that finally maintains (or establishes) the RRC connection with the terminal device in this CHO procedure) is cell D. The MRO-related information recorded by the terminal device is the same as the MRO-related information recorded in scenario VI situation (1). For the related description, reference may be made to the description of scenario VI situation (1), and the details are not repeated here.

[0193] In the situation (3) of Scenario VI, the cell that finally provides services to the terminal device (or, if understood in a different way, the cell that finally maintains (or sustains) the RRC connection with the terminal device in this CHO procedure) is Cell A. The MRO information recorded by the terminal device is the same as the MRO-related information recorded in the situation (1) of Scenario VI. However, in the situation (3) of Scenario VI, the difference is that the information recorded regarding the cell that finally provides services to the terminal device in this CHO procedure is the information regarding source cell A, rather than the information regarding Cell D. For relevant explanations, reference may be made to the explanation of the situation (1) of Scenario VI, and the details will not be repeated here.

[0194] In the situation (4) of Scenario VI, the cell that finally provides services to the terminal device (or, if understood in a different way, the cell that finally maintains (or establishes) the RRC connection with the terminal device in this CHO procedure) is Cell A. The MRO information recorded by the terminal device is the same as the MRO-related information recorded in the situation (3) of Scenario VI. For relevant explanations, reference may be made to the explanation of the situation (3) of Scenario VI, and the details will not be repeated here.

[0195] Step S602:

[0196] In a possible embodiment, the terminal device triggers the transmission of MRO-related information. For example, based on the received conditional handover configuration information, the terminal device normally hands over to a candidate cell that meets the handover trigger condition. Therefore, the terminal device may send the MRO-related information recorded in this CHO procedure to the network device to which the cell that finally provides service to the terminal device in this CHO procedure belongs. For example, in Scenario II, the terminal device normally hands over to candidate cell C, and therefore, the terminal device may send the MRO-related information recorded in this CHO procedure to the network device to which cell C belongs. Optionally, the network device to which the cell that finally provides service to the terminal device in this CHO procedure belongs may send the MRO-related information received from the terminal device to the source network device. For example, in Scenario II, the network device to which cell C belongs sends the MRO-related information received from the terminal device to the network device to which cell A belongs (i.e., the source network device).

[0197] Alternatively, for example, when the handover to a candidate cell fails based on the received conditional handover configuration information by the terminal device, and the terminal device starts a re-establishment procedure and the re-establishment is successful, that is, when the cell that finally provides service to the terminal device in this CHO procedure is the cell in which the RRC connection is re-established, the terminal device may send the MRO-related information recorded in this CHO procedure to the network device to which the cell that finally provides service to the terminal device in this CHO procedure belongs. For example, in the situation (1) of Scenario I or the situation (2) of Scenario I, the terminal device successfully re-establishes the RRC connection with cell D. Therefore, the terminal device may send the MRO-related information recorded in this CHO procedure to the network device to which cell D belongs. Optionally, the network device to which the cell that finally provides service to the terminal device in this CHO procedure belongs may send the MRO-related information received from the terminal device to the source network device. For example, in the situation (1) of Scenario I or the situation (2) of Scenario I, the network device to which cell D belongs sends the MRO-related information received from the terminal device to the network device to which cell A belongs (i.e., the source network device).

[0198] Alternatively, for example, when the handover to a candidate cell fails based on the received conditional handover configuration information, if the terminal device remains in the source cell, that is, if the cell that finally provides service to the terminal device in this CHO procedure is the source cell, the terminal device may send the MRO-related information recorded in this CHO procedure to the network device to which the cell that finally provides service to the terminal device in this CHO procedure belongs. For example, in the situation (3) of Scenario I, the terminal device remains in the source cell after this CHO procedure. Therefore, the terminal device may send the MRO-related information recorded in this CHO procedure to the network device to which Cell A belongs (i.e., the source network device). The network device may adjust the conditional handover-related parameters based on the received MRO-related information.

[0199] In another possible implementation, the terminal device triggers the transmission of MRO-related information after receiving a request message sent by a second network device. For example, the request message may be a UE Information Request message. This implementation will be described in detail below.

[0200] Optionally, in this embodiment of the present application, when the terminal device can record MRO-related information, the terminal device may send third indication information to the second network device. The third indication information is used to notify the second network device that the terminal device can record MRO-related information. The third indication information may be included in an RRC message. The RRC message may be, for example, an RRC establishment complete message or an RRC reconfiguration complete message or an RRC re-establishment complete message or another RRC message. This is not particularly limited in this embodiment of the present application. Alternatively, the third indication information may be included in a physical layer message (such as uplink control information (UCI)) or a media access control (MAC) layer message (media access control element (MAC CE)). This is not particularly limited in this embodiment of the present application. Regarding the opportunity to send the third indication information, for example, in a possible implementation, the third indication information may be sent when the terminal device sends an RRC re-establishment complete message after successful re-establishment. In another possible implementation, the third indication information may be sent when the terminal device sends an RRC reconfiguration complete message to the network device that has been normally accessed after successful execution of conditional handover. This is not particularly limited in this embodiment of the present application.

[0201] Optionally, in this embodiment of the present application, the third indication information may be in binary. For example, "1" indicates that the terminal device can record MRO-related information, and "0" indicates that the terminal device cannot record MRO-related information. Alternatively, the third indication information may be a boolean value. For example, "TRUE" indicates that the terminal device can record MRO-related information, and "FALSE" indicates that the terminal device cannot record MRO-related information. Alternatively, the third indication information may be an information element. For example, the information element may be a mobility robustness optimization capability (such as MRO capability) information element, or the information element may be expressed or named in other forms. This is not particularly limited in this embodiment of the present application. When the message sent by the terminal device includes an information element, it indicates that the terminal device can record MRO-related information. When the message sent by the terminal device does not include an information element, it indicates that the terminal device cannot record MRO-related information.

[0202] After receiving the third indication information from the terminal device, the second network device may send a request message to the terminal device to request the terminal device to report MRO-related information. For example, the request message may be a UEInformationRequest message.

[0203] Optionally, in this embodiment of the present application, the second network device may send a request message to the terminal device after receiving the third indication information sent by the terminal device, or the second network device may send a request message to the terminal device without receiving the third indication information. In other words, whether the third indication information is received is not a prerequisite for the second network device to send a request message. This is not particularly limited in this embodiment of the present application.

[0204] In a possible embodiment, the second network device may be the network device to which the cell belongs, and the cell is a normally accessed cell that satisfies the handover trigger condition determined by the terminal device based on the currently received conditional handover configuration information. Two candidate cells, namely cell B and cell C, are configured in the conditional handover configuration information. When the terminal device determines, based on the conditional handover configuration information, that cell C satisfies the handover trigger condition and the terminal device successfully accesses cell C, the network device to which cell C belongs is the second network device.

[0205] In another possible embodiment, the second network device is the network device to which the cell belongs, and the cell is the cell in which the terminal device starts RRC connection reestablishment after receiving the conditional handover configuration information. For example, when the terminal device determines that none of the configured M candidate cells satisfy the handover trigger condition based on the currently received conditional handover configuration information, or at least one of the configured M candidate cells satisfies the handover trigger condition but the terminal device fails to access at least one cell that satisfies the handover trigger condition, or other situations occur, the terminal device starts the reestablishment procedure. Therefore, the network device to which the cell determined by the terminal device for reestablishment belongs is the second network device. For example, the terminal device selects an appropriate new cell E according to the S criterion, executes the RRC reestablishment procedure with cell E, and successfully reestablishes the RRC connection with cell E. Therefore, the network device to which cell E belongs is the second network device.

[0206] In another possible embodiment, the second network device may be a network device to which the subsequently accessed cell belongs, and the cell is normally accessed by the terminal device after the terminal device receives the conditional handover configuration information. For example, after the terminal device determines a cell that meets the handover trigger condition based on the currently received conditional handover configuration information, and after the terminal device has successfully accessed the cell, the terminal device may subsequently access another network device for further movement or the start of re-establishment or for other reasons. The network device receives third instruction information transmitted by the terminal device, or the network device transmits a request message to the terminal device requesting the terminal device to report MRO-related information. Accordingly, the network device is the second network device.

[0207] In another possible implementation, after receiving the conditional handover configuration information, the terminal device starts the re-establishment procedure. After the re-establishment is successful, the terminal device may subsequently access another network device due to further movement or the start of re-establishment or other reasons. Another network device receives the third instruction information sent by the terminal device, or another network device sends a request message to the terminal device (for example, sends a UEInformationRequest message to the terminal device). Therefore, another network device is the second network device. For example, two candidate cells (such as cell B and cell C) are configured in the conditional handover configuration information. The terminal device determines, based on the conditional handover configuration information, that cell C meets the handover trigger condition, and the terminal device normally accesses cell C. After the terminal device has successfully handed over to cell C, the network device to which cell C belongs does not send a UEInformationRequest message to the UE. Therefore, the terminal device does not send MRO-related information to the network device to which cell C belongs. Subsequently, due to further movement or the start of re-establishment or other reasons, the terminal device normally accesses cell F. After receiving a request message (such as a UEInformationRequest message) sent by the network device to which cell F belongs, the terminal device sends MRO-related information to the network device to which cell F belongs.

[0208] Optionally, in this embodiment of the present application, the first failure cause value corresponding to the candidate target cell and / or the second failure cause value corresponding to the cell to be determined within the MRO-related information may be transmitted via an RRC message. For example, the RRC message may be a UEInformationReponse message. This is not particularly limited in this embodiment of the present application. In one embodiment, the terminal device uses Message 2 to transmit the first failure cause value corresponding to the candidate target cell and / or the second failure cause value corresponding to the cell to be determined. Message 2 may be an RRC message such as a UEInformationReponse message. Optionally, Message 2 may further include the first information carried in the MRO-related information. In other words, the first information, the first failure cause value corresponding to the candidate target cell, and / or the second failure cause value corresponding to the cell to be determined may be transmitted via the same RRC message. For the related description of the first information, reference may be made to the foregoing description of the first information, and the details are not repeated here. Alternatively, the first information may be transmitted via another RRC message such as Message 3. In other words, the first information, the first failure cause value corresponding to the candidate target cell, and / or the second failure cause value corresponding to the cell to be determined may be transmitted via different RRC messages. Message 3 may be an RRC message such as a UEInformationReponse message. This is not particularly limited in this embodiment of the present application. Optionally, in this embodiment of the present application, Message 2 may further include the second information carried in the MRO-related information. For the related description of the second information, reference may be made to the foregoing description of the second information, and the details are not repeated here. Alternatively, the second information may be included in Message 3. When the second information is included in Message 2 or Message 3, the second information may be transmitted simultaneously with the related information generated when the conditional handover fails.In other words, the second information may be transmitted via the same message as that used to transmit the first information, the first failure cause value corresponding to the candidate target cell, and / or the second failure cause value corresponding to the cell to be determined. Optionally, the second information may alternatively be transmitted separately. For example, the terminal device transmits message 4 to the second network device, and message 4 includes the second information. Message 4 may be an RRC message such as a UEInformationReponse message. This is not particularly limited in this embodiment of the present application.

[0209] Optionally, in this embodiment of the present application, when the second information is transmitted separately, a possible situation is that the terminal device determines that a cell among the candidate cells meets the handover trigger condition and successfully executes a random access procedure with the cell to successfully access the cell. For example, when two candidate cells, namely cell B and cell C, are configured, the terminal device receives conditional handover configuration information, and then determines that cell B meets the handover trigger condition and successfully accesses cell B. After the terminal device successfully hands over to cell B, this CHO procedure may be considered to have ended. In this CHO procedure, the terminal device may record information about cell B. Since the access to cell B is successful, the terminal device may skip the determination of whether cell C meets the handover trigger condition, and the terminal device does not record information about cell C. In this case, in this CHO procedure, the terminal device skips recording information regarding the failure of the conditional handover. In other words, the terminal device may skip sending information regarding the failure of the conditional handover to the second network device. That is, the terminal device may skip sending message 2 or message 3 to the second network device. For example, the terminal device skips sending information about cell C to the second network device, but sends the second information to the second network device, that is, the terminal device sends message 4 to the second network device. For example, the terminal device sends information about cell B to the second network device.

[0210] Optionally, in this embodiment of the present application, when the conditional handover mechanism coexists with the conventional handover mechanism, Message 2, Message 3, or Message 4 may further include third information or fourth information carried in the MRO information. For the related descriptions of the third information and the fourth information, reference may be made to the foregoing descriptions of the corresponding information. Specifically, the terminal device may transmit information regarding the failure of the conventional handover together with the related information generated in the conditional handover procedure. Specifically, the third information and the fourth information may be transmitted via the same message used to transmit the first information, the second information, the first failure cause value corresponding to the candidate target cell, and / or the second failure cause value corresponding to the cell to be determined, or the terminal device may use a new message (a message other than Message 2, Message 3, and Message 4) to transmit information regarding the failure of the conventional handover. That is, the terminal device may transmit information regarding the failure of the conventional handover separately from the related information generated in the conditional handover procedure. This is not particularly limited in the present application.

[0211] Optionally, in this embodiment of the present application, when the terminal device transmits MRO-related information, if the terminal device transmits one or more of the first information, the second information, the third information, the fourth information, and the first failure cause value corresponding to the candidate target cell and / or the second failure cause value corresponding to the cell to be determined, the transmission may be performed at the granularity of the terminal device or the cell. This is not particularly limited in the present application. In one example, all MRO information is included in message 2, and message 2 is an RRC message. When the terminal device transmits information, the information may be transmitted via one message 2. Specifically, the terminal device uses one message 2 to transmit the recorded MRO-related information of each of the source cell, the candidate target cell and / or the cell to be determined, the first target cell, and the cell that finally provides services to the terminal device in this CHO procedure. That is, message 2 is at the granularity of the terminal device. For example, in the situation (1) of scenario III in step S601 described above, if the terminal device uses one message 2 to transmit MRO-related information in this CHO procedure, message 2 includes the first failure cause value corresponding to cell B and cell C, the information related to cell B, the information related to cell C, the first time information corresponding to cell B, and the first time information corresponding to cell C, the information related to cell D, and the information related to cell A. Regarding the first failure cause value, message 2 may include only one first failure cause value. Specifically, the first failure cause value corresponds to both cell B and cell C, or message 2 may include two first failure cause values, and the two first failure cause values correspond to cell B and cell C respectively. This is not particularly limited in this embodiment of the present application. The information related to cell A (or cell B, or cell C, or cell D) includes the cell identity information of cell A (or cell B, or cell C, or cell D) and / or the cell signal quality information of cell A (or cell B, or cell C, or cell D).

[0212] Alternatively, for example, the terminal device may transmit MRO information in a plurality of messages 2. Specifically, the terminal device may separately transmit MRO-related information corresponding to each cell. The MRO-related information is recorded by the terminal device, and the cell includes each of the candidate target cell and / or the cell to be determined, as well as the first target cell. That is, message 2 is at the cell granularity. When message 2 is transmitted at the cell granularity, information about the source cell and information about the cell that finally provides service to the terminal device in this CHO procedure may be transmitted separately, or may be transmitted together with the MRO-related information of the candidate target cell or the cell to be determined. This is not particularly limited in this application. For example, in the situation (1) of scenario III in step S601 described above, regarding cell B and cell C, the terminal device may transmit information about cell B via message 2a. Message 2a includes the first failure cause value corresponding to cell B and other MRO-related information corresponding to cell B (for example, information about cell B and the first time information corresponding to cell B). The terminal device may transmit information about cell C via another message 2b. Message 2b includes the first failure cause value corresponding to cell C and other MRO-related information corresponding to cell C (for example, information about cell C and the first time information corresponding to cell C). Regarding the source cell A and cell D where the RRC connection is re-established, the information about cell A (for example, information unique to cell A) may be transmitted via another message 2c, message 2a, or message 2b, and the information about cell D (for example, information unique to cell D) may be transmitted via another message 2d, or message 2a, or message 2b, or message 2c. This is not particularly limited in this embodiment of this application. The information about cell A (or cell B, or cell C, or cell D) includes the cell identity information of cell A (or cell B, or cell C, or cell D) and / or the cell signal quality information of cell A (or cell B, or cell C, or cell D).

[0213] Step S603:

[0214] It should be noted that when the network device that sends a request message requesting the terminal device to report MRO-related information to the terminal device is the network device to which the source cell belongs, the second network device and the first network device are the same network device. In this case, step S603 does not need to be executed.

[0215] Optionally, in this embodiment of the present application, when the second network device sends MRO-related information to the first network device, the MRO-related information may be included in one message for transmission, or different contents included in the MRO-related information may be transmitted via different messages, or when understood in different ways, when transmitting the MRO-related information, the transmission may be executed at the granularity of the terminal device or the cell. This is not particularly limited in this embodiment of the present application. For related descriptions, reference may be made to the corresponding description of step S602, and the details will not be repeated here.

[0216] Optionally, in this embodiment of the present application, regarding the candidate target cell corresponding to the first failure cause value, one possible cause of the access failure is that the quality of the candidate target cell is always relatively low, or the signal quality of the candidate target cell rapidly decreases or is unstable. After receiving the first failure cause value corresponding to the candidate target cell, the second network device sends the received first failure cause value corresponding to the candidate target cell to the first network device.

[0217] After receiving the first failure cause value, the first network device may perform corresponding processing according to the first failure cause value. For example, according to the first failure cause value, the first network device may reconfigure another candidate cell or adjust relevant parameters of a previously configured candidate cell (which may also be understood as configuring conditional handover related parameters). In a possible implementation, when the first network device subsequently configures a candidate cell in, for example, the next or subsequent CHO procedure, the candidate target cell may be excluded, that is, the candidate target cell is no longer configured as a candidate cell. In this way, in the next or subsequent conditional handover, the terminal device no longer needs to determine whether the candidate target cell meets the handover trigger condition, and as a result, the energy consumption of the terminal device and the complexity of the implementation of the terminal device are reduced.

[0218] Alternatively, another possible cause of access failure is that the handover trigger condition configured by the first network device is inappropriate. For example, the handover trigger criteria configured for the handover trigger condition are inappropriate (in an example where event A3 is configured, the parameter Q configured by the first network device for the event may be slightly low). The terminal device determines that the candidate cell meets the handover trigger condition based on the conditional handover configuration information. The candidate cell meets the handover trigger condition, but the signal quality of the cell does not meet the requirements for successful access of the terminal device. Therefore, the terminal device fails to access the cell. After receiving the first failure cause value corresponding to the candidate target cell, the second network device transmits the received first failure cause value corresponding to the candidate target cell to the first network device.

[0219] After receiving the first failure cause value, the first network device may perform corresponding processing according to the first failure cause value. For example, according to the first failure cause value, the first network device may reconfigure another candidate cell or adjust relevant parameters of a previously configured candidate cell (which may also be understood as configuring conditional handover related parameters). In a possible implementation, in an example where event A3 is configured, when the first network device continues to configure the handover trigger condition, it may increase the value of parameter Q to be configured.

[0220] It should be noted that the network device configuring the candidate cell may be the first network device or the network device to which the candidate cell belongs.

[0221] Optionally, in this embodiment of the present application, for the cell to be determined corresponding to the second failure cause value, a possible reason for not satisfying the handover trigger condition is that the signal quality of the cell to be determined is always low. After receiving the second failure cause value corresponding to the cell to be determined, the second network device transmits the received second failure cause value corresponding to the cell to be determined to the first network device.

[0222] After receiving the second failure cause value, the first network device may perform corresponding processing according to the second failure cause value. For example, according to the second failure cause value, the first network device may reconfigure another candidate cell or adjust the relevant parameters of the previously configured candidate cell (which may also be understood as configuring conditional handover related parameters). In a possible implementation, when the first network device subsequently configures a candidate cell (e.g., in the next or subsequent CHO procedure), the cell to be determined is excluded, that is, the cell to be determined is no longer configured as a candidate cell. Therefore, in the next or subsequent conditional handover, the terminal device no longer needs to determine whether the cell to be determined meets the handover trigger condition, and as a result, the energy consumption of the terminal device and the complexity of the implementation of the terminal device are reduced.

[0223] Alternatively, another possible cause for not meeting the handover trigger condition is that the signal quality of the cell to be determined is relatively high, but the handover trigger condition configured by the first network device is inappropriate (in the example where event A3 is configured, the parameter Q configured for the event may be slightly high, or in the example where event A5 is configured, the parameter K configured for event A5 may be slightly high, and / or the configured parameter L may be slightly low). After receiving the second failure cause value corresponding to the cell to be determined, the second network device transmits the received second failure cause value corresponding to the cell to be determined to the first network device.

[0224] After receiving the second failure cause value, the first network device may perform corresponding processing according to the second failure cause value. For example, according to the second failure cause value, the first network device may reconfigure another candidate cell or adjust the relevant parameters of the previously configured candidate cell (which may also be understood as configuring conditional handover related parameters). In a possible embodiment, after receiving the second failure cause value corresponding to the cell to be determined, the first network device may appropriately adjust the relevant parameters. In an example where event A3 is configured, when the first network device continues to configure the handover trigger condition, the value of parameter Q configured may be decreased.

[0225] Optionally, in this embodiment of the present application, after receiving the first time information and / or the second time information, the second network device transmits the received first time information and / or the second time information to the first network device. After receiving the first time information and / or the second time information, the first network device may perform corresponding processing according to the first time information and / or the second time information. For example, according to the first time information and / or the second time information, the first network device may reconfigure another candidate cell or adjust the relevant parameters of the previously configured candidate cell (which may also be understood as configuring conditional handover related parameters). In a possible embodiment, for a cell where conditional handover fails (such as a candidate target cell or a cell to be determined), within the time interval from the time when the terminal device receives the conditional handover configuration information to the time when the terminal device transmits message 2, if the network device reconfigures the relevant parameters within the handover trigger condition corresponding to the cell where conditional handover fails (using A3 as an example, parameter Q is reconfigured). In this case, the network device may delete, discard, or ignore the relevant information corresponding to the cell where conditional handover fails received from the terminal device, and may not adjust the relevant parameters within the handover trigger condition corresponding to the cell where conditional handover fails.

[0226] Optionally, in this embodiment of the present application, after receiving the third information or the fourth information, the second network device transmits the third information or the fourth information to the first network device. After receiving the third information or the fourth information, the first network device may perform corresponding processing according to the third information or the fourth information. For example, the first network device reconfigures the relevant parameters of the conventional handover according to the third information or the fourth information. For example, in a possible implementation, when the terminal device receives a handover message but fails to access the second target cell, a possible reason is that the second target cell does not permit access by the terminal device. In the subsequent conventional handover procedure, the first network device may not configure the cell as the target cell, or in the subsequent conditional handover procedure, the first network device may not configure the cell as a candidate cell. Alternatively, for example, in a possible implementation, the terminal device does not receive a handover message, and a possible reason is that the parameters configured by the network are inappropriate. In the subsequent conventional handover procedure, the first network device may adjust the parameters of the relevant events within the measurement configuration. As an example, when using event A3 (in the prior art, when configuring event A3, the first network device configures an offset (such as P), and when the signal quality of the adjacent cell is P higher than the signal quality of the serving cell, the UE is triggered to report a measurement report), the terminal device may fail to report a measurement report because the configured parameter P is too high. Therefore, the network device does not trigger the conventional handover preparation procedure, and the first network device does not transmit a handover message to the terminal device. As a result, the terminal device does not receive a handover message. Therefore, the first network device subsequently decreases the value of P according to the information regarding the handover failure, and as a result, the purpose of optimization may be achieved.

[0227] Based on the information transmission method provided in this embodiment of the present application, the terminal device transmits information regarding a candidate target cell and / or information regarding a cell to be determined, which are generated in a conditional handover procedure, to a second network device. For example, the information reported by the terminal device may include a first failure cause value corresponding to a candidate cell (i.e., a candidate target cell) that satisfies the handover trigger condition and to which the terminal device fails to access, a second failure cause value corresponding to a candidate cell (i.e., a cell to be determined) that does not satisfy the handover trigger condition, information regarding the source cell, information regarding the candidate target cell, first time information corresponding to each of at least one candidate target cell, information regarding the cell to be determined, and second time information corresponding to each of at least one cell to be determined. The second network device transmits the information reported by the terminal device to the first network device, whereby the first network device can appropriately optimize handover parameters under the conditional handover mechanism according to the information regarding the candidate target cell and / or the information regarding the cell to be determined.

[0228] Naturally, in each of the foregoing embodiments, the method and / or steps implemented by the terminal device may alternatively be implemented by components (such as chips or circuits) available in the terminal device, and the method and / or steps implemented by the first network device may alternatively be implemented by components (such as chips or circuits) available in the first network device, and the method and / or steps implemented by the second network device may alternatively be implemented by components (such as chips or circuits) available in the second network device.

[0229] The above mainly describes the solutions in the embodiments of the present application from the perspective of the interaction between network elements. Correspondingly, an embodiment of the present application further provides a communication device. The communication device is configured to implement any of the above-mentioned methods. The communication device may be a terminal device, or a device including the terminal device, or a component (such as a chip or a circuit) that can be used in the terminal device in the embodiments of the above-mentioned method. Or the communication device may be a first network device, or a device including the first network device, or a component (such as a chip or a circuit) that can be used in the first network device in the embodiments of the above-mentioned method. Or the communication device may be a second network device, or a device including the second network device, or a component (such as a chip or a circuit) that can be used in the second network device in the embodiments of the above-mentioned method. Naturally, in order to implement the above-mentioned functions, the communication device includes corresponding hardware structures and / or software modules for executing each of the functions. Those skilled in the art should easily recognize that the present application can be implemented by hardware or a combination of hardware and computer software in combination with the examples of units and algorithm steps described in the embodiments disclosed in this specification. Whether the function is executed by hardware or by hardware driven by computer software depends on the specific application of the technical solution and design constraints. Those skilled in the art may use different methods to implement the described functions for each specific application, but their implementation manners should not be considered to exceed the scope of the present application.

[0230] In this embodiment of the present application, the communication device can be divided into functional modules according to the embodiment of the foregoing method. For example, each of the functions may correspond to a functional module, or two or more functions may be integrated into one processing module. The integrated module may be implemented in the form of hardware or in the form of a software functional module. It should be noted that the division into modules in this embodiment of the present application is only an example and is merely a division into logical functions. In actual embodiments, other division methods may be used.

[0231] For example, the communication device is the terminal device in the embodiment of the foregoing method. FIG. 7 is a schematic structural diagram of the terminal device 70. The terminal device 70 includes a receiving module 701 and a transmitting module 702. The receiving module 701, also known as the receiving unit, is configured to implement a receiving function and may be, for example, a receiving circuit, a receiver, or a communication interface. The transmitting module 702, also known as the transmitting unit, is configured to implement a transmitting function and may be, for example, a transmitting circuit, a transmitter, a transmitter, or a communication interface.

[0232] The receiving module 701 is configured to receive conditional handover configuration information. The conditional handover configuration information includes a handover trigger condition and information about M candidate cells, where M is a positive integer. The transmitting module 702 is configured to transmit a first failure cause value corresponding to at least one candidate target cell and / or a second failure cause value corresponding to at least one cell to be determined. The at least one candidate target cell includes X cells that satisfy the handover trigger condition among the M candidate cells, and the at least one cell to be determined includes Y cells that do not satisfy the handover trigger condition among the M candidate cells. X and Y are natural numbers, and X + Y is less than or equal to M.

[0233] The first failure cause value indicates that the candidate target cell satisfies the handover trigger condition, but the terminal device fails to access the candidate target cell. Alternatively, the first failure cause value includes the failure cause value at the first level and the failure cause value at the second level. The failure cause value at the first level indicates that the conditional handover of the terminal device fails. The failure cause value at the second level indicates that the candidate target cell satisfies the handover trigger condition, but the terminal device fails to access the candidate target cell. The second failure cause value indicates that the cell to be determined does not satisfy the handover trigger condition. Alternatively, the second failure cause value includes the failure cause value at the third level and the failure cause value at the fourth level. The failure cause value at the third level indicates that the conditional handover of the terminal device fails. The failure cause value at the fourth level indicates that the cell to be determined does not satisfy the handover trigger condition.

[0234] Optionally, the transmission module 702 is further configured to transmit one or more of the information related to the source cell, the information related to the candidate target cell, the first time information corresponding to each of the at least one candidate target cell, the information related to the cell to be determined, and the second time information corresponding to each of the at least one cell to be determined. The first time information includes information regarding the time interval from the time when the terminal device receives the conditional handover configuration information to the time when the terminal device triggers a handover to the first candidate target cell, information regarding the time interval from the time when the terminal device triggers a handover to the first candidate target cell to the time when the terminal device fails to access the first candidate target cell, and information regarding the time interval from the time when the terminal device fails to access the first candidate target cell to the time when the terminal device transmits the first failure cause value and / or the second failure cause value. The first candidate target cell is any one of the at least one candidate target cell.

[0235] The second time information includes information on the time interval from the time when the terminal device receives the conditional handover configuration information to the time when the terminal device determines that the first target cell does not satisfy the handover trigger condition, and information on the time interval from the time when the terminal device determines that the first target cell does not satisfy the handover trigger condition to the time when the terminal device transmits the first failure cause value and / or the second failure cause value. The first target cell is any one of at least one target cell. Alternatively, the second time information includes information on the time interval from the time when the terminal device receives the conditional handover configuration information to the time when the terminal device stops determining whether the first target cell satisfies the handover trigger condition, and information on the time interval from the time when the terminal device stops determining whether the first target cell satisfies the handover trigger condition to the time when the terminal device transmits the first failure cause value and / or the second failure cause value.

[0236] Optionally, the transmission module 702 is further configured to transmit one or more of information on the first target cell, and the third cause value and the third time information corresponding to the first target cell. The first target cell is a cell that has been successfully accessed by the terminal device among M candidate cells.

[0237] The third cause value indicates that the terminal device has successfully performed a conditional handover. The third time information includes information on the time interval from the time when the terminal device receives the conditional handover configuration information to the time when the terminal device triggers a handover to the first target cell, information on the time interval from the time when the terminal device triggers a handover to the first target cell to the time when the terminal device successfully accesses the first target cell, and information on the time interval from the time when the terminal device successfully accesses the first target cell to the time when the terminal device transmits one or more of information on the first target cell, the third cause value, and the third time information.

[0238] Optionally, the terminal device 70 further includes a processing module 703. The processing module 703 is configured to determine that the receiving module 701 has not received a Radio Resource Control (RRC) reconfiguration message before the first target cell is successfully accessed.

[0239] Optionally, the receiving module 701 is further configured to receive an RRC reconfiguration message before the first target cell is successfully accessed, and the RRC reconfiguration message includes information about a second target cell. The processing module 703 is further configured to determine that the access to the second target cell has failed.

[0240] All relevant contents of the steps in the embodiments of the foregoing method may be cited in the description of the functions of the corresponding functional modules, and details are not repeated here.

[0241] In this embodiment, the terminal device 70 is presented in the form of functional modules obtained by integration. Here, "module" may mean a specific ASIC, circuit, processor, and memory, integrated logic circuit, and / or another device capable of providing any of the foregoing functions for executing one or more software or firmware programs. In a simple embodiment, those skilled in the art may recognize that the terminal device 70 may be in the form of the terminal device shown in FIG. 2 or FIG. 4.

[0242] For example, the processor 401 of the terminal device shown in FIG. 2 or FIG. 4 may call computer-executable instructions stored in the memory 402 to cause the terminal device to execute the information transmission method according to the embodiments of the foregoing method.

[0243] The functions or implementation procedures of the receiving module 701, the transmitting module 702, and the processing module 703 in FIG. 7 can be implemented by the processor 401 of the terminal device shown in FIG. 2 or FIG. 4 by calling computer-executable instructions stored in the memory 402. Alternatively, the functions or implementation procedures of the receiving module 701 and the transmitting module 702 in FIG. 7 may be implemented by the transceiver 403 of the terminal device shown in FIG. 2 or FIG. 4, and the functions or implementation procedures of the processing module 703 in FIG. 7 may be implemented by the processor 401 of the terminal device shown in FIG. 2 or FIG. 4 by calling computer-executable instructions stored in the memory 402.

[0244] The terminal device 70 provided in this embodiment can implement an information transmission method. Therefore, for the technical effects that can be achieved by the terminal device 70, reference can be made to the method embodiment, and the details are not repeated here.

[0245] Alternatively, for example, the communication device is the first network device in the foregoing method embodiment. FIG. 8 is a schematic structural diagram of the first network device. The first network device 80 includes a receiving module 801 and a transmitting module 802. The receiving module 801, also known as a receiving unit, is configured to implement a receiving function and may be, for example, a receiving circuit, a receiver, a receiver, or a communication interface. The transmitting module 802, also known as a transmitting unit, is configured to implement a transmitting function and may be, for example, a transmitting circuit, a transmitter, a transmitter, or a communication interface.

[0246] The transmission module 802 is configured to transmit conditional handover configuration information to the terminal device. The conditional handover configuration information includes a handover trigger condition and information about M candidate cells, where M is a positive integer. The reception module 801 is configured to receive, from a second network device, a first failure cause value corresponding to at least one candidate target cell and / or a second failure cause value corresponding to at least one determination target cell. At least one candidate target cell includes X cells that satisfy the handover trigger condition among the M candidate cells, and at least one determination target cell includes Y cells that do not satisfy the handover trigger condition among the M candidate cells. X and Y are natural numbers, and X + Y is less than or equal to M.

[0247] The first failure cause value indicates that the candidate target cell satisfies the handover trigger condition, but the terminal device fails to access the candidate target cell. Alternatively, the first failure cause value includes a first-level failure cause value and a second-level failure cause value. The first-level failure cause value indicates that the conditional handover of the terminal device fails. The second-level failure cause value indicates that the candidate target cell satisfies the handover trigger condition, but the terminal device fails to access the candidate target cell. The second failure cause value indicates that the determination target cell does not satisfy the handover trigger condition. Alternatively, the second failure cause value includes a third-level failure cause value and a fourth-level failure cause value. The third-level failure cause value indicates that the conditional handover of the terminal device fails. The fourth-level failure cause value indicates that the determination target cell does not satisfy the handover trigger condition.

[0248] Optionally, the reception module 801 is further configured to receive, from the second network device, one or more of information about the source cell, information about the candidate target cell, first time information corresponding to each of the at least one candidate target cell, information about the determination target cell, and second time information corresponding to each of the at least one determination target cell.

[0249] The first time information includes information regarding the time interval from the time when the terminal device receives the conditional handover configuration information to the time when the terminal device triggers a handover to the first candidate target cell, information regarding the time interval from the time when the terminal device triggers a handover to the first candidate target cell to the time when the terminal device fails to access the first candidate target cell, and information regarding the time interval from the time when the terminal device fails to access the first candidate target cell to the time when the terminal device transmits the first failure cause value and / or the second failure cause value. The first candidate target cell is any one of at least one candidate target cell.

[0250] The second time information includes information regarding the time interval from the time when the terminal device receives the conditional handover configuration information to the time when the terminal device determines that the first target cell for determination does not satisfy the handover trigger condition, and information regarding the time interval from the time when the terminal device determines that the first target cell for determination does not satisfy the handover trigger condition to the time when the terminal device transmits the first failure cause value and / or the second failure cause value. The first target cell for determination is any one of at least one target cell for determination. Alternatively, the second time information includes information regarding the time interval from the time when the terminal device receives the conditional handover configuration information to the time when the terminal device stops determining whether the first target cell for determination satisfies the handover trigger condition, and information regarding the time interval from the time when the terminal device stops determining whether the first target cell for determination satisfies the handover trigger condition to the time when the terminal device transmits the first failure cause value and / or the second failure cause value.

[0251] Optionally, the receiving module 801 is further configured to receive, from a second network device, information regarding a first target cell, and one or more of a third cause value and third time information corresponding to the first target cell. The first target cell is a cell that has been successfully accessed by the terminal device among M candidate cells.

[0252] The third cause value indicates that the terminal device has successfully performed a conditional handover. The third time information includes information regarding the time interval from the time when the terminal device receives the conditional handover configuration information to the time when the terminal device triggers a handover to the first target cell, information regarding the time interval from the time when the terminal device triggers a handover to the first target cell to the time when the terminal device successfully accesses the first target cell, and information regarding the time interval from the time when the terminal device successfully accesses the first target cell to the time when the terminal device transmits one or more of information regarding the first target cell, the third cause value, and the third time information.

[0253] All relevant content of the steps in the foregoing method embodiments can be cited in the description of the functions of the corresponding functional modules, and details are not repeated here.

[0254] In this embodiment, the first network device 80 is presented in the form of a functional module obtained by integration. Here, "module" can mean a specific ASIC, circuit, processor, and memory for executing one or more software or firmware programs, integrated logic circuits, and / or another device capable of providing any of the foregoing functions. In a simple embodiment, those skilled in the art can recognize that the first network device 80 can be in the form of the first network device shown in FIG. 2.

[0255] For example, the processor 301a of the first network device shown in FIG. 2 can call computer-executable instructions stored in the memory 302a to cause the first network device to execute the information transmission method according to the foregoing method embodiments.

[0256] Specifically, the functions or implementation procedures of the receiving module 801 and the transmitting module 802 in FIG. 8 can be implemented by the transceiver 303a of the first network device shown in FIG. 2.

[0257] The first network device 80 provided in this embodiment can implement the information transmission method. Therefore, for the technical effects that can be achieved by the first network device 80, reference can be made to the method embodiments, and the details are not repeated here.

[0258] Alternatively, for example, the communication device is the second network device in the foregoing method embodiments. FIG. 9 is a schematic structural diagram of the second network device. The second network device 90 includes a receiving module 901 and a transmitting module 902. The receiving module 901, also known as a receiving unit, is configured to implement a receiving function and may be, for example, a receiving circuit, a receiver, a receiver, or a communication interface. The transmitting module 902, also known as a transmitting unit, is configured to implement a transmitting function and may be, for example, a transmitting circuit, a transmitter, a transmitter, or a communication interface.

[0259] The receiving module 901 is configured to receive, from the terminal device, a first failure cause value corresponding to at least one candidate target cell and / or a second failure cause value corresponding to at least one cell to be determined. The at least one candidate target cell includes X cells that satisfy the handover trigger condition among M candidate cells, and the at least one cell to be determined includes Y cells that do not satisfy the handover trigger condition among the M candidate cells. X and Y are natural numbers, and X + Y is less than or equal to M. The M candidate cells and the handover trigger condition are configured by conditional handover configuration information.

[0260] The first failure cause value indicates that the candidate target cell satisfies the handover trigger condition, but the terminal device fails to access the candidate target cell. Alternatively, the first failure cause value includes a first-level failure cause value and a second-level failure cause value. The first-level failure cause value indicates that the conditional handover of the terminal device fails. The second-level failure cause value indicates that the candidate target cell satisfies the handover trigger condition, but the terminal device fails to access the candidate target cell. The second failure cause value indicates that the cell to be determined does not satisfy the handover trigger condition. Alternatively, the second failure cause value includes a third-level failure cause value and a fourth-level failure cause value. The third-level failure cause value indicates that the conditional handover of the terminal device fails. The fourth-level failure cause value indicates that the cell to be determined does not satisfy the handover trigger condition.

[0261] Optionally, the receiving module 901 is further configured to receive, from the terminal device, one or more of information about the source cell, information about the candidate target cell, first time information corresponding to each of the at least one candidate target cell, information about the cell to be determined, and second time information corresponding to each of the at least one cell to be determined.

[0262] The first time information includes information regarding the time interval from the point in time when the terminal device receives the conditional handover configuration information to the point in time when the terminal device triggers a handover to the first candidate target cell, information regarding the time interval from the point in time when the terminal device triggers a handover to the first candidate target cell to the point in time when the terminal device fails to access the first candidate target cell, and information regarding the time interval from the point in time when the terminal device fails to access the first candidate target cell to the point in time when the terminal device transmits the first failure cause value and / or the second failure cause value. The first candidate target cell is any one of at least one candidate target cell.

[0263] The second time information includes information regarding the time interval from the point in time when the terminal device receives the conditional handover configuration information to the point in time when the terminal device determines that the first target cell under determination does not satisfy the handover trigger condition, and information regarding the time interval from the point in time when the terminal device determines that the first target cell under determination does not satisfy the handover trigger condition to the point in time when the terminal device transmits the first failure cause value and / or the second failure cause value. The first target cell under determination is any one of at least one target cell under determination. Alternatively, the second time information includes information regarding the time interval from the point in time when the terminal device receives the conditional handover configuration information to the point in time when the terminal device stops determining whether the first target cell under determination satisfies the handover trigger condition, and information regarding the time interval from the point in time when the terminal device stops determining whether the first target cell under determination satisfies the handover trigger condition to the point in time when the terminal device transmits the first failure cause value and / or the second failure cause value.

[0264] Optionally, the receiving module 901 is further configured to receive, from the terminal device, information regarding the first target cell, and one or more of the third cause value and the third time information corresponding to the first target cell. The first target cell is a cell that has been successfully accessed by the terminal device among M candidate cells.

[0265] The third cause value indicates that the terminal device has successfully executed the conditional handover. The third time information includes information on the time interval from when the terminal device receives the conditional handover configuration information to when the terminal device triggers the handover to the first target cell, information on the time interval from when the terminal device triggers the handover to the first target cell to when the terminal device successfully accesses the first target cell, and information on the time interval from when the terminal device successfully accesses the first target cell to when the terminal device transmits one or more of the information on the first target cell, the third cause value, and the third time information.

[0266] The transmission module 902 is configured to transmit the first failure cause value corresponding to the candidate target cell and / or the second failure cause value corresponding to the cell to be determined to the first network device. At least one candidate target cell includes X cells that satisfy the handover trigger condition among the M candidate cells, and at least one cell to be determined includes Y cells that do not satisfy the handover trigger condition among the M candidate cells. X and Y are natural numbers, and X + Y is less than or equal to M. The M candidate cells and the handover trigger condition are configured by the conditional handover configuration information.

[0267] Optionally, the transmission module 902 is further configured to transmit one or more of the information on the source cell, the information on the candidate target cell, the first time information corresponding to each of the at least one candidate target cell, the information on the cell to be determined, and the second time information corresponding to each of the at least one cell to be determined to the first network device.

[0268] Optionally, the transmitting module 902 is further configured to transmit to the first network device one or more of information regarding the first target cell, as well as a third cause value and third time information corresponding to the first target cell. The first target cell is a cell that has been successfully accessed by the terminal device among the M candidate cells.

[0269] All relevant content of the steps in the foregoing method embodiments may be cited in the description of the functions of the corresponding functional modules, and details are not repeated here.

[0270] In this embodiment, the second network device 90 is presented in the form of a functional module obtained by integration. Here, "module" may mean a specific ASIC, circuit, processor, and memory for executing one or more software or firmware programs, integrated logic circuits, and / or another device capable of providing any of the foregoing functions. In a simple embodiment, those skilled in the art may recognize that the second network device 90 may be in the form of the second network device shown in FIG. 2.

[0271] For example, the processor 301b of the second network device shown in FIG. 2 may call computer-executable instructions stored in the memory 302b to cause the second network device to execute the information transmission method according to the foregoing method embodiments.

[0272] Specifically, the functions or implementation procedures of the receiving module 901 and the transmitting module 902 in FIG. 9 may be implemented by the transceiver 303b of the second network device shown in FIG. 2.

[0273] The second network device 90 provided in this embodiment may implement the information transmission method. Therefore, for the technical effects that may be achieved by the second network device 90, reference may be made to the method embodiments, and details are not repeated here.

[0274] Optionally, one embodiment of the present application further provides a communication device (for example, the communication device may be a chip or a chip system). The communication device includes a processor configured to implement the method described in any of the method embodiments. In a possible design, the communication device further includes a memory. The memory is configured to store the necessary program instructions and data. The processor may call the program code stored in the memory to instruct the communication device to implement any of the methods of the method embodiments. Alternatively, the memory may not be included in the communication device. When the communication device is a chip system, the communication device may include a chip or may include a chip and other individual elements. This is not particularly limited in this embodiment of the present application.

[0275] All or part of the foregoing embodiments may be implemented using software, hardware, firmware, or any combination thereof. When a software program is used to implement the embodiments, the embodiments may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer instructions are loaded and executed on a computer, all or part of the procedures or functions according to the embodiments of the present application are generated. The computer may be a general-purpose computer, a dedicated computer, a computer network, or other programmable devices. The computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from a website, computer, server, or data center to another website, computer, server, or data center in a wired (e.g., coaxial cable, optical fiber, or digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, or microwave) manner. The computer-readable storage medium may be any usable medium accessible by a computer or a data storage device such as a server or data center incorporating one or more usable media. The usable media may be magnetic media (e.g., floppy disk, hard disk, or magnetic tape), optical media (e.g., DVD), or semiconductor media (e.g., solid state disk (SSD)), etc. In the embodiments of the present application, the computer may include the foregoing devices.

[0276] This application is described with reference to embodiments. However, in the process of implementing this application for which protection is claimed, those skilled in the art can understand and implement other variations of the disclosed embodiments by considering the accompanying drawings, the disclosed content, and the appended claims. In the claims, "comprising" does not exclude other components or other steps, and "a" or "one" does not exclude a plurality of meanings. A single processor or another unit may perform several functions listed in the claims. Although several means are described in different dependent claims, this does not mean that these means cannot be combined to produce better effects.

[0277] This application is described with reference to specific features and their embodiments. However, it is clear that various modifications and combinations can be made to them without departing from the spirit and scope of this application. Correspondingly, this specification and the accompanying drawings are merely examples of the description of this application defined by the appended claims, and are considered to be any or all of the modified examples, variations, combination examples, or equivalent examples that fall within the scope of this application. It is clear that those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. This application is intended to include these modifications and variations of this application if they are within the scope of protection defined by the following claims and their equivalent technologies.

Description of Reference Numerals

[0278] 10 Communication system 30 Communication system 70 Terminal device 80 First network device 90 Second network device 110 Processor 120 External memory interface 121 Internal memory 130 USB interface 140 Charging Management Module 141 Power Management Module 142 Battery 150 Mobile Communication Module 160 Wireless Communication Module 170 Audio Module 170A Speaker 170B Receiver 170C Microphone 170D Earphone Interface 180 Sensor Module 180A Pressure Sensor 180B Gyroscope Sensor 180C Barometric Pressure Sensor 180D Magnetic Sensor 180E Acceleration Sensor 180F Distance Sensor 180G Optical Proximity Sensor 180H Fingerprint Sensor 180J Temperature Sensor 180K Touch Sensor 180L Ambient Light Sensor 180M Bone Conduction Sensor 190 Button 191 Motor 192 Indicator 193 Camera 194 Display Screen 195 SIM Card Interface 301 Processor 301a Processor 301b Processor 302 Memory 302a Memory 302b Memory 303 Transceiver 303a Transceiver 303b Transceiver 304 Network Interface 304a Network Interface 304b Network Interface 401 Processor 402 Memory 403 Transceiver 404 Output Device 405 Input Device 701 Receiver Module 702 Transmitter Module 703 Processing Module 801 Receiver Module 802 Transmitter Module 901 Receiver Module 902 Transmitter Module

Claims

Claim 1 A communication method applied in a terminal device, comprising: receiving conditional handover configuration information, wherein the conditional handover configuration information includes a handover trigger condition and information about M candidate cells, and M is a positive integer; transmitting a first failure cause value corresponding to at least one candidate target cell and first time information about the elapsed time between the execution of a configuration of one of the at least one candidate target cell and the reception of the conditional handover configuration information; wherein the at least one candidate target cell satisfies the handover trigger condition and includes X cells among the M candidate cells that the terminal device has failed to access; a method. The method according to claim 1, wherein the random access attempt performed by the terminal device includes: determining, based on the conditional handover configuration information, that a first candidate cell satisfies the handover trigger condition; and performing a random access to the first candidate cell by the terminal device. Claim 3 The first failure cause value indicates that the candidate target cell satisfies the handover trigger condition, but the terminal device has failed to access the candidate target cell; or The first failure cause value includes a first-level failure cause value and a second-level failure cause value, and the first-level failure cause value indicates that the conditional handover of the terminal device has failed. The method according to claim 1. Claim 4 The method further includes: transmitting the following information, namely: information about the source cell and information about one of the at least one candidate target cell. The method according to any one of claims 1 to 3. Claim 5 The first time information includes: information about the time interval from the time when the terminal device triggers a handover to a first candidate target cell to the time when the terminal device fails to access the first candidate target cell, and information about the time interval from the time when the terminal device fails to access the first candidate target cell to the time when the terminal device transmits the first failure cause value. ​ including at least one of them, wherein the first candidate target cell is any one of the at least one candidate target cell The method according to claim 1

6. The method is the following information, namely a step of transmitting information regarding a first target cell and one or more of a third cause value and third time information corresponding to the first target cell, wherein the first target cell is a cell that has been successfully accessed by the terminal device among the M candidate cells The method according to any one of claims 1 to 5, including

7. Before the terminal device successfully accesses the first target cell, the method is a step of determining that a radio resource control (RRC) reconfiguration message has not been received, wherein the RRC reconfiguration message is used to instruct the terminal device to perform a conventional handover, or a step of receiving the RRC reconfiguration message and determining that access to a second target cell has failed by the terminal device, wherein the RRC reconfiguration message includes information regarding the second target cell The method according to claim 6, including

8. An information transmission method, comprising a step of transmitting conditional handover configuration information to a terminal device, wherein the conditional handover configuration information includes a handover trigger condition and information regarding M candidate cells, and M is a positive integer, and a step of receiving, from a second network device, a first failure cause value corresponding to at least one candidate target cell and first time information regarding the elapsed time between the execution of a configuration of one of the at least one candidate target cell and the reception of the conditional handover configuration information, wherein the at least one candidate target cell satisfies the handover trigger condition and includes X cells among the M candidate cells to which the terminal device has failed to access A method, including

9. The first failure cause value indicates that the candidate target cell satisfies the handover trigger condition, but the terminal device has failed to access the candidate target cell, or The first failure cause value includes the failure cause value at the first level and the failure cause value at the second level, and the failure cause value at the first level indicates that the conditional handover of the terminal device has failed. The method according to claim 8.

10. The method includes: The following information, namely: Receiving, from the second network device, information about a source cell and information about one of the at least one candidate target cell. The method according to claim 8 or 9, including this step.

11. The first time information includes: At least one of information about the time interval from the time when the terminal device triggers a handover to a first candidate target cell to the time when the terminal device fails to access the first candidate target cell, and information about the time interval from the time when the terminal device fails to access the first candidate target cell to the time when the terminal device transmits the first failure cause value. The first candidate target cell is any one of the at least one candidate target cell. The method according to claim 8.

12. The method includes: The following information, namely: Receiving, from the second network device, information about a first target cell and one or more of a third cause value and third time information corresponding to the first target cell. The first target cell is a cell that the terminal device has successfully accessed among the M candidate cells. The method according to any one of claims 8 to 11, including this step.

13. An information transmission method, including: Receiving, from a terminal device, first time information about the elapsed time between the execution of a configuration of one of the at least one candidate target cell and the reception of conditional handover configuration information, corresponding to the first failure cause value of the at least one candidate target cell. The at least one candidate target cell satisfies a handover trigger condition and includes X cells among the M candidate cells that the terminal device has failed to access. The M candidate cells and the handover trigger condition are configured by the conditional handover configuration information. Transmitting the first failure cause value and the first time information to a first network device. A method comprising

14. wherein the first failure cause value indicates that the candidate target cell satisfies the handover trigger condition, but the terminal device fails to access the candidate target cell, or wherein the first failure cause value includes a first-level failure cause value and a second-level failure cause value, and the first-level failure cause value indicates that the conditional handover of the terminal device has failed, The method according to claim 13.

15. The method comprises receiving, from the terminal device, the following information, namely information regarding the source cell and information regarding one of the at least one candidate target cell, and transmitting one or more of the following information to the first network device The method according to claim 13 or 14, comprising

16. wherein the first time information includes at least one of information regarding the time interval from the time when the terminal device triggers a handover to a first candidate target cell to the time when the terminal device fails to access the first candidate target cell, and information regarding the time interval from the time when the terminal device fails to access the first candidate target cell to the time when the terminal device transmits the first failure cause value, and the first candidate target cell is any one of the at least one candidate target cell, The method according to claim 13.

17. A communication device that is a terminal device or a device applicable to the terminal device, the communication device comprising a receiving module and a processing module, and configured to perform the method according to any one of claims 1 to 7.

18. A communication device comprising a receiving module and a processing module, and configured to perform the method according to any one of claims 8 to 12.

19. A communication device comprising a receiving module and a processing module, and configured to perform the method according to any one of claims 13 to 16.

20. A computer-readable storage medium including instructions that, when executed on a computer, cause the computer to execute the method according to any one of claims 1 to 7. A computer-readable storage medium including instructions that, when executed on a computer, cause the computer to execute the method according to any one of claims 8 to 12 or cause the computer to execute the method according to any one of claims 13 to 16.

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