US-12621738-B2 - Method of adjusting network parameters due to conditional handover failure caused by cell signal and listen before talk problems

Abstract

A communication method for a terminal device includes receiving a conditional handover (CHO) command from a source network device. The communication method also includes selecting, by the terminal device, a cell in response to a radio link failure (RLF) in a source cell before the terminal device determines a target cell. The target cell is determined according to the CHO command. The communication method additionally includes sending first information to a network device. The first information includes a first parameter. The first parameter is related to a CHO failure caused by the RLF in the source cell.

Inventors

• Yedan Wu
• Tingting GENG
• Chunhua YOU

Assignees

• HUAWEI TECHNOLOGIES CO., LTD.

Dates

Publication Date

20260505

Application Date

20230424

Claims (20)

1. 1 . A communication method for a terminal device, wherein the communication method comprises: receiving a conditional handover (CHO) command from a source network device, wherein the CHO command comprises information about one or more candidate cells; selecting, by the terminal device, a cell in response to a radio link failure (RLF) in a source cell before the terminal device determines a target cell, wherein the target cell is determined according to the CHO command; and sending, first information to a network device, wherein the first information comprises a first parameter, and the first parameter is related to a CHO failure caused by the RLF in the source cell, wherein the first information causes the source network device to: adjust a network parameter based on the first information, wherein the network parameter comprises at least one of a parameter used by the terminal device to perform CHO between cells and a parameter used for listen before talk (LBT); determine whether the CHO failure is caused by a cell signal problem or an LBT problem in the candidate cell, wherein the cell signal problem includes a signal quality used during the CHO failure, and the LBT problem includes a time period associated with a time at which the terminal device fails to perform random access in the candidate cell; in response to determining that the CHO failure is caused by the cell signal problem, adjust a trigger value of a measurement report and CHO execution condition information; and in response to determining that the CHO failure is caused by the LBT problem, adjust a maximum quantity of consecutive LBT failures and LBT duration.
2. 2 . The communication method according to claim 1 , wherein the first parameter comprises at least one of indication information indicating that the RLF occurs in the source cell, or information about a time period from time at which the terminal device receives the CHO command to time at which the RLF occurs in the source cell.
3. 3 . The communication method according to claim 1 , wherein the cell selected by the terminal device is a first cell, the first cell is one of the one or more candidate cells, and the communication method further comprises: in response to the terminal device failing to perform listen before talk (LBT) in the first cell, or successfully performing LBT and failing to perform random access in the first cell, initiating a radio resource control (RRC) reestablishment procedure, wherein in response to the terminal device failing to perform LBT in the first cell, the first information is caused to further comprise a second parameter, and the second parameter is related to the CHO failure caused by the LBT failure of the terminal device in the first cell; or in response to the terminal device successfully performing LBT and failing to perform random access in the first cell, the first information is caused to further comprise a third parameter, and the third parameter is related to the CHO failure caused by the successful LBT and the random access failure of the terminal device in the first cell.
4. 4 . The communication method according to claim 3 , wherein the second parameter comprises at least one of: indication information indicating that the terminal device fails to perform LBT in the first cell, information about a time period from time at which the terminal device starts to perform LBT in the first cell to time at which the terminal device fails to perform LBT in the first cell, information about a time period from the time at which the terminal device fails to perform LBT in the first cell to time at which the terminal device initiates the RRC reestablishment procedure, or information about a time period from the time at which the terminal device fails to perform LBT in the first cell to time at which the terminal device sends the first information.
5. 5 . The communication method according to claim 3 , wherein the third parameter comprises at least one of: indication information indicating that the terminal device successfully performs LBT in the first cell, indication information indicating that the terminal device fails to perform random access in the first cell, information about a time period from time at which the terminal device starts to perform LBT in the first cell to time at which the terminal device successfully performs LBT in the first cell, information about a time period from the time at which the terminal device successfully performs LBT in the first cell to time at which the terminal device fails to perform random access in the first cell, information about a time period from the time at which the terminal device fails to perform random access in the first cell to time at which the terminal device initiates the RRC reestablishment procedure, or information about a time period from the time at which the terminal device fails to perform random access in the first cell to time at which the terminal device sends the first information.
6. 6 . The communication method according to claim 1 , wherein the cell selected by the terminal device is a second cell, the second cell is one of the one or more candidate cells, and the communication method further comprises: in response to successfully performing listen before talk (LBT) and random access in the second cell, handing over, to the second cell, wherein the first information further comprises a fourth parameter, and the fourth parameter is related to a successful CHO caused by the successfully performed LBT and random access of the terminal device in the second cell.
7. 7 . The communication method according to claim 6 , wherein the fourth parameter comprises at least one of: indication information indicating that the terminal device successfully performs LBT in the second cell, indication information indicating that the terminal device successfully performs random access in the second cell, information about a time period from time at which the terminal device starts to perform LBT in the second cell to time at which the terminal device successfully performs LBT in the second cell, information about a time period from the time at which the terminal device successfully performs LBT in the second cell to time at which the terminal device successfully performs random access in the second cell, or information about a time period from the time at which the terminal device successfully performs random access in the second cell to time at which the terminal device sends the first information.
8. 8 . The communication method according to claim 1 , wherein the communication method further comprises: in response to the cell selected by the terminal device being a third cell, initiating a radio resource control (RRC) reestablishment procedure in the third cell, wherein the third cell is a cell other than the candidate cell.
9. 9 . A communication apparatus, comprising: a processor; and a memory having instructions stored thereon that, when executed by the processor, cause the communication apparatus to: receive a conditional handover (CHO) command from a source network device, wherein the CHO command comprises information about one or more candidate cells; cause a terminal device to select a cell in response to a radio link failure (RLF) in a source cell before the terminal device determines a target cell, wherein the target cell is determined according to the CHO command; and send, first information to a network device, wherein the first information comprises a first parameter, and the first parameter is related to a CHO failure caused by the RLF in the source cell, wherein the first information causes the source network device to: adjust a network parameter based on the first information, wherein the network parameter comprises at least one of a parameter used by the terminal device to perform CHO between cells and a parameter used for listen before talk (LBT); determine whether the CHO failure is caused by a cell signal problem or an LBT problem in the candidate cell, wherein the cell signal problem includes a signal quality used during the CHO failure, and the LBT problem includes a time period associated with a time at which the terminal device fails to perform random access in the candidate cell; in response to determining that the CHO failure is caused by the cell signal problem, adjust a trigger value of a measurement report and CHO execution condition information; and in response to determining that the CHO failure is caused by the LBT problem, adjust a maximum quantity of consecutive LBT failures and LBT duration.
10. 10 . The communication apparatus according to claim 9 , wherein the first parameter comprises at least one of indication information indicating that the RLF occurs in the source cell, or information about a time period from time at which the terminal device receives the CHO command to time at which the RLF occurs in the source cell.
11. 11 . The communication apparatus according to claim 9 , wherein the cell selected by the terminal device is a first cell, the first cell is one of the one or more candidate cells, and the communication apparatus is further caused to: in response to the terminal device failing to perform listen before talk (LBT) in the first cell, or successfully performing LBT and failing to perform random access in the first cell, initiate a radio resource control (RRC) reestablishment procedure, wherein in response to the terminal device failing to perform LBT in the first cell, the first information is caused to further comprise a second parameter, and the second parameter is related to the CHO failure caused by the LBT failure of the terminal device in the first cell; or in response to the terminal device successfully performing LBT and failing to perform random access in the first cell, the first information is caused to further comprise a third parameter, and the third parameter is related to the CHO failure caused by the successful LBT and the random access failure of the terminal device in the first cell.
12. 12 . The communication apparatus according to claim 11 , wherein the second parameter comprises at least one of: indication information indicating that the terminal device fails to perform LBT in the first cell, information about a time period from time at which the terminal device starts to perform LBT in the first cell to time at which the terminal device fails to perform LBT in the first cell, information about a time period from the time at which the terminal device fails to perform LBT in the first cell to time at which the terminal device initiates the RRC reestablishment procedure, or information about a time period from the time at which the terminal device fails to perform LBT in the first cell to time at which the terminal device sends the first information.
13. 13 . The communication apparatus according to claim 11 , wherein the third parameter comprises at least one of: indication information indicating that the terminal device successfully performs LBT in the first cell, indication information indicating that the terminal device fails to perform random access in the first cell, information about a time period from time at which the terminal device starts to perform LBT in the first cell to time at which the terminal device successfully performs LBT in the first cell, information about a time period from the time at which the terminal device successfully performs LBT in the first cell to time at which the terminal device fails to perform random access in the first cell, information about a time period from the time at which the terminal device fails to perform random access in the first cell to time at which the terminal device initiates the RRC reestablishment procedure, or information about a time period from the time at which the terminal device fails to perform random access in the first cell to time at which the terminal device sends the first information.
14. 14 . The communication apparatus according to claim 9 , wherein the cell selected by the terminal device is a second cell, the second cell is one of the one or more candidate cells, and the communication apparatus is further caused to: in response to successfully performing listen before talk (LBT) and random access in the second cell, hand over, to the second cell, wherein the first information further comprises a fourth parameter, and the fourth parameter is related to a successful CHO caused by the successfully performed LBT and random access of the terminal device in the second cell.
15. 15 . The communication apparatus according to claim 14 , wherein the fourth parameter comprises at least one of: indication information indicating that the terminal device successfully performs LBT in the second cell, indication information indicating that the terminal device successfully performs random access in the second cell, information about a time period from time at which the terminal device starts to perform LBT in the second cell to time at which the terminal device successfully performs LBT in the second cell, information about a time period from the time at which the terminal device successfully performs LBT in the second cell to time at which the terminal device successfully performs random access in the second cell, or information about a time period from the time at which the terminal device successfully performs random access in the second cell to time at which the terminal device sends the first information.
16. 16 . The communication apparatus according to claim 9 , wherein the communication apparatus is further caused to: in response to the cell selected by the terminal device being a third cell, initiate a radio resource control (RRC) reestablishment procedure in the third cell, wherein the third cell is a cell other than the candidate cell.
17. 17 . A communication apparatus, comprising: a processor; and a memory having instructions stored thereon that, when executed by the processor, cause the communication apparatus to: send a conditional handover (CHO) command to a terminal device that includes information about a candidate cell; receive first information, wherein the first information comprises a first parameter, and the first parameter is related to a CHO failure caused by a radio link failure (RLF) in a source cell; adjust a network parameter based on the first information, wherein the network parameter comprises at least one of a parameter used by the terminal device to perform CHO between cells and a parameter used for listen before talk (LBT); determine whether the CHO failure is caused by a cell signal problem or an LBT problem in the candidate cell, wherein the cell signal problem includes a signal quality used during the CHO failure, and the LBT problem includes a time period associated with a time at which the terminal device fails to perform random access in the candidate cell; in response to determining that the CHO failure is caused by the cell signal problem, adjust a trigger value of a measurement report and CHO execution condition information; and in response to determining that the CHO failure is caused by the LBT problem, adjust a maximum quantity of consecutive LBT failures and LBT duration.
18. 18 . The communication apparatus according to claim 17 , wherein the first information is received from the terminal device by way of a network device that forwards the first information from the terminal device to the communication apparatus.
19. 19 . The communication apparatus according to claim 17 , wherein the communication apparatus is further caused to: generate second information based on the first information; and send the second information to a network device, wherein the second information instructs the network device to adjust the network parameter.
20. 20 . The communication apparatus according to claim 17 , wherein the communication apparatus is a source network device or a core network device.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of International Patent Application No. PCT/CN2020/122749, filed on Oct. 22, 2020, the disclosure of which is hereby incorporated by reference in its entirety TECHNICAL FIELD This application relates to the field of wireless network technologies, and in particular, to a communication method and a related device. BACKGROUND In a conditional handover (CHO) procedure, a network parameter, for example, a handover parameter, is one of key factors that directly affect a handover success rate, and a network device increases the handover success rate by adjusting the network parameter. A channel access (LBT) failure or a radio link failure ( ) may lead to a failure of the CHO procedure. Because the network device cannot learn a cause of the failure of the CHO procedure, the network device cannot adjust the network parameter. This affects system performance. SUMMARY Embodiments of this application provide a communication method and a related device, to improve system performance. According to a first aspect, an embodiment of this application provides a communication method, including: A terminal device receives a conditional handover CHO command from a source base station, where the CHO command includes information about a plurality of candidate cells; the terminal device determines, according to the CHO command, to hand over from a source cell to a target cell; when the terminal device fails to perform channel access LBT in the target cell, or successfully performs LBT and fails to perform random access in the target cell, the terminal device selects a cell; and the terminal device sends first information to a network device. The first information includes a first parameter, and the first parameter is related to a CHO failure caused by the LBT failure in the target cell; or the first information includes a second parameter, and the second parameter is related to a CHO failure caused by the successful LBT and the random access failure in the target cell. The first information is reported to the network device, so that the network device can determine a cause of the CHO failure in the target cell based on the first information, and adjust a corresponding network parameter. Therefore, system performance is improved. In a possible design, the first parameter includes at least one of the following: indication information indicating that the target cell meets an execution condition of the CHO command and LBT fails to be performed in the target cell, information about a time period from time at which the terminal device receives the CHO command to time at which the target cell is determined, and information about a time period from the time at which the target cell is determined to time at which the terminal device fails to perform LBT in the target cell. The network device determines, by using the first parameter, a cause of handing over from the source cell to the target cell, to adjust the network parameter. Therefore, the system performance is improved. In another possible design, the second parameter includes at least one of the following: indication information indicating that the target cell meets an execution condition of the CHO command and LBT is successfully performed in the target cell, indication information indicating that the terminal device fails to perform random access in the target cell, information about a time period from time at which the terminal device receives the CHO command to time at which the target cell is determined, information about a time period from the time at which the target cell is determined to time at which the terminal device successfully performs LBT in the target cell, and information about a time period from the time at which the terminal device successfully performs LBT in the target cell to time at which the terminal device fails to perform random access in the target cell. The network device determines, by using the second parameter, a cause of handing over from the source cell to the target cell, to adjust the network parameter. Therefore, the system performance is improved. In another possible design, after failing to perform CHO in the target cell, the terminal device selects the cell. The cell selected by the terminal device is a first cell, and the first cell is one of the candidate cells. When failing to perform LBT in the first cell, or successfully performing LBT and failing to perform random access in the first cell, the terminal device initiates a radio resource control RRC reestablishment procedure. When the terminal device fails to perform channel access LBT in the first cell, the first information further includes a third parameter, and the third parameter is related to the CHO failure caused by the LBT failure of the terminal device in the first cell; or when the terminal device successfully performs LBT and fails to perform random access in the first cell, the first information further