US-12628228-B2 - Re-establishment method and communication apparatus

US12628228B2US 12628228 B2US12628228 B2US 12628228B2US-12628228-B2

Abstract

A re-establishment method includes: If a link failure occurs in a handover procedure of a terminal device, the terminal device releases configuration information used in a source cell. The terminal device further determines a re-establishment request message based on configuration information used in the target cell, and sends the re-establishment request message in a re-establishment cell. A method for selecting a re-establishment cell and releasing configuration information when a link failure occurs in a dual active protocol stack (DAPS) handover procedure of the terminal device reduces memory consumption of the terminal device.

Inventors

Liangliang Zhang
Junren Chang
Zhenhua DAI

Assignees

HUAWEI TECHNOLOGIES CO., LTD.

Dates

Publication Date: 20260512
Application Date: 20220818
Priority Date: 20200219

Claims (20)

1 . A re-establishment method, comprising: receiving, by a terminal device, a handover command from a source network device, wherein the handover command indicates that the terminal device is to perform a dual active protocol stack (DAPS) handover from a source cell to a target cell, the handover command comprises first configuration information, and the first configuration information is configuration information used in the target cell; performing, by the terminal device, the DAPS handover, and after successfully accessing the target cell and before receiving a first message from a target network device indicating to release the source cell, determining that link failure has occurred in the target cell; releasing, by the terminal device, second configuration information, wherein the second configuration information is configuration information used in the source cell; determining, by the terminal device, a first cell; determining, by the terminal device, a radio resource control (RRC) re-establishment request message based on the first configuration information, wherein the RRC re-establishment request message comprises a cell-radio network temporary identifier (C-RNTI) used in the target cell and a short message authentication code for integrity (short MAC-I) used in the target cell; and sending, by the terminal device, the RRC re-establishment request message in the first cell.
2 . The method according to claim 1 , wherein determining that link failure has occurred is further based on determining that one or more of the following cases occur in the target cell or the source cell: an RRC connection reconfiguration failure occurs; integrity check fails; a quantity of radio link control (RLC) retransmissions reaches a preset threshold; a timer T310 expires; or random access fails and a timer T311 is not running.
3 . The method according to claim 1 , wherein determining that link failure has occurred is based on determining that an RRC connection reconfiguration failure occurs in the target cell, and wherein determining that the RRC connection reconfiguration failure occurs in the target cell comprises: receiving a first reconfiguration message from the target network device, wherein the first reconfiguration message comprises third configuration information, and the third configuration information is new configuration information used in the target cell; performing reconfiguration based on the first reconfiguration message; and determining that the RRC connection reconfiguration failure occurs in the target cell.
4 . The method according to claim 3 , wherein the first reconfiguration message is received from the target network device in a DAPS handover procedure, after successfully accessing the target cell and before receiving the first message indicating to release the source cell from the target network device.
5 . The method according to claim 3 , wherein the first reconfiguration message further comprises first indication information, and the first indication information indicates to release the second configuration information.
6 . The method according to claim 1 , wherein determining that link failure has occurred is based on determining that one or more of the following cases occur in a handover procedure: inter-system handover fails; or intra-system handover fails.
7 . The method according to claim 1 , wherein the first cell is a cell to which the target network device belongs or a cell to which a non-source network device belongs.
8 . The method according to claim 1 , wherein the RRC re-establishment request message comprises second indication information, and the second indication information indicates the link failure.
9 . The method according to claim 1 , wherein the RRC re-establishment request message further comprises: a physical cell identifier (PCI) of the target cell.
10 . The method according to claim 1 , further comprising: in a DAPS handover procedure, starting a timer after successfully accessing the target cell; before receiving the first message indicating to release the source cell from the target network device, determining that the timer expires; and sending a second message to the target network device, wherein the second message indicates that the first message has not been received or indicates that the first message failed to be received.
11 . An apparatus, comprising: one or more processors; and one or more memories coupled to the one or more processors and storing programming instructions; wherein the one or more processors are configured to execute the programming instructions to facilitate performance of the following by the apparatus: receiving a handover command from a source network device, wherein the handover command indicates that the apparatus is to perform a dual active protocol stack (DAPS) handover from a source cell to a target cell, the handover command comprises first configuration information, and the first configuration information is configuration information used in the target cell; performing the DAPS handover, and after successfully accessing the target cell and before receiving a first message indicating to release the source cell from a target network device, determining that link failure has occurred in the target cell; releasing second configuration information, wherein the second configuration information is configuration information used in the source cell; determining a first cell; determining a radio resource control (RRC) re-establishment request message based on the first configuration information, wherein the RRC re-establishment request message comprises a cell-radio network temporary identifier (C-RNTI) used in the target cell and a short message authentication code for integrity (short MAC-I) used in the target cell; and sending the RRC re-establishment request message in the first cell.
12 . The apparatus according to claim 11 , wherein determining that link failure has occurred is further based on determining that one or more of the following cases occur in the target cell or the source cell: an RRC connection reconfiguration failure occurs; integrity check fails; a quantity of radio link control (RLC) retransmissions reaches a preset threshold; a timer T310 expires; or random access fails and a timer T311 is not running.
13 . The apparatus according to claim 11 , wherein determining that link failure has occurred is based on determining that an RRC connection reconfiguration failure occurs in the target cell, wherein determining that the RRC connection reconfiguration failure occurs in the target cell comprises: receiving a first reconfiguration message from the target network device, wherein the first reconfiguration message comprises third configuration information, and the third configuration information is new configuration information used in the target cell; performing reconfiguration based on the first reconfiguration message; and determining that the RRC connection reconfiguration failure occurs in the target cell.
14 . The apparatus according to claim 13 , wherein the first reconfiguration message is received from the target network device in a DAPS handover procedure, after successfully accessing the target cell and before receiving the first message indicating to release the source cell from the target network device.
15 . The apparatus according to claim 13 , wherein the first reconfiguration message further comprises first indication information, and the first indication information indicates to release the second configuration information.
16 . The apparatus according to claim 11 , wherein determining that link failure occurs is based on determining that one or more of the following cases occur in a handover procedure: inter-system handover fails; or intra-system handover fails.
17 . The apparatus according to claim 11 , wherein the first cell is a cell to which the target network device belongs or a cell to which a non-source network device belongs.
18 . The apparatus according to claim 11 , wherein the RRC re-establishment request message comprises second indication information, and the second indication information indicates the link failure.
19 . The apparatus according to claim 11 , wherein the RRC re-establishment request message further comprises: a physical cell identifier (PCI) of the target cell.
20 . A non-transitory computer-readable storage medium having processor-executable instructions stored thereon, wherein the processor-executable instructions, when executed, facilitate: receiving a handover command from a source network device, wherein the handover command indicates a dual active protocol stack (DAPS) handover from a source cell to a target cell, the handover command comprises first configuration information, and the first configuration information is configuration information used in the target cell; performing the DAPS handover, and after successfully accessing the target cell and before receiving a first message indicating to release the source cell from a target network device, determining that link failure has occurred in the target cell; releasing second configuration information, wherein the second configuration information is configuration information used in the source cell; determining a first cell; determining a radio resource control (RRC) re-establishment request message based on the first configuration information, wherein the RRC re-establishment request message comprises a cell-radio network temporary identifier (C-RNTI) used in the target cell and a short message authentication code for integrity (short MAC-I) used in the target cell; and sending the RRC re-establishment request message in the first cell.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of International Application No. PCT/CN2021/076803, filed on Feb. 19, 2021, which claims priority to Chinese Patent Application No. 202010103185.4, filed on Feb. 19, 2020. The disclosures of the aforementioned applications are hereby incorporated by reference in their entireties. TECHNICAL FIELD This application relates to the communication field, and more specifically, to a re-establishment method and a communication apparatus in the communication field. BACKGROUND Currently, in a conventional radio resource control (RRC) re-establishment procedure after a radio link failure (RLF), a re-establishment request message sent by a terminal device to a network device to which a re-establishment cell belongs includes a parameter corresponding to configuration information that is being used by the terminal device. However, in a procedure in which the terminal device hands over from a source cell to a target cell, if a link failure occurs, the terminal device needs to re-establish an RRC connection. For example, when the terminal device successfully hands over to the target cell but has not received, from a target network device, a message indicating the terminal device to release a link between a source network device and the terminal device, the terminal device receives a reconfiguration message from the target network device, and a reconfiguration failure occurs on the terminal device. Consequently, a radio link failure occurs on the terminal device in the target cell. In this case, the terminal device stores both configuration information used in the source cell and configuration information used in the target cell. Therefore, how the terminal device performs re-establishment based on the stored configuration information becomes an urgent problem to be resolved. SUMMARY This application provides a re-establishment method, which is applicable to a link failure scenario in a handover procedure. A terminal device may initiate RRC re-establishment based on stored configuration information. According to a first aspect, a re-establishment method is provided, where the method is applicable to a terminal device. The method includes: receiving a handover command from a source network device, where the handover command indicates the terminal device to hand over from a source cell to a target cell, the handover command includes first configuration information, and the first configuration information is configuration information used in the target cell; determining that a link failure occurs; releasing second configuration information, where the second configuration information is configuration information used in the source cell; determining a first cell; determining a radio resource control (RRC) re-establishment request message based on the first configuration information; and sending the RRC re-establishment request message in the first cell. The first cell is a cell in which re-establishment is initiated. Based on the foregoing technical solution, in a procedure of handing over from the source cell to the target cell the terminal device releases the configuration information used in the source cell if the link failure occurs, so that a part of memory of the terminal device can be released. This simplifies implementation of the terminal device. In addition, after the configuration information used in the source cell is released, the terminal device has only the configuration information used in the target cell. This resolves a problem that the terminal device cannot send the RRC re-establishment request message based on the stored configuration information. According to a second aspect, a re-establishment method is provided, where the method is applicable to a terminal device. The method includes: receiving a handover command from a source network device, where the handover command indicates the terminal device to hand over from a source cell to a target cell, the handover command includes first configuration information, and the first configuration information is configuration information used in the target cell; determining that a link failure occurs; releasing the first configuration information; determining a first cell; determining an RRC re-establishment request message based on second configuration information, where the second configuration information is configuration information used in the source cell; and sending the RRC re-establishment request message in the first cell. The first cell is a cell in which re-establishment is initiated. Based on the foregoing technical solution, in a procedure of handing over from the source cell to the target cell the terminal device releases the configuration information used in the target cell if the link failure occurs, so that a part of memory of the terminal device can be released. This simplifies implementation of the terminal device. In addition, after the configuration information used in the