Methods executed by user equipment and user equipment

Abstract

The present invention proposes a method executed by a user equipment UE, comprising: when a DAPS switching failure occurs during the UE's execution of a dual activation protocol stack DAPS switching, if a source base station radio link failure, i.e., a source base station RLF, is not detected, the UE falls back to the source base station link, and does not generate and save switching failure information for the DAPS switching failure in a link failure report; and when falling back to the source base station link, if the UE detects that a source base station RLF has occurred, the UE records and saves link failure information for the source base station RLF in a link failure report.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and more particularly, to a method executed by a user equipment and a corresponding user equipment. Background Art

[0002] In June 2018, the 3rd Generation Partnership Project (3GPP) RAN#80 plenary meeting approved a new research project for 5G technical standards (see non-patent document: RP-181433: New WID on NR (New Radio) mobility enhancements) and a new research project for Long Term Evolution (LTE) Release 16 (see non-patent document: RP-181544). One of the research objectives of these two projects is to find a solution to meet one of the mobility requirements: seamless switching, that is, to meet zero milliseconds or close to zero milliseconds of switching interruption time during the switching process of changing the UE's serving cell. Among the solutions being studied to reduce the switching interruption time, one solution is the Dual Active Protocol Stack mechanism. In the DAPS mechanism, after receiving the switching command, the UE does not cut off the link (data transmission) with the source base station during the switching process to the target base station, but can simultaneously maintain the connection and data transmission between the target base station and the source base station, thereby avoiding the delay caused by service interruption due to disconnection from the source base station before accessing the target base station during the switching process. Summary of the invention

[0003] In order to solve at least part of the above problems, the present invention provides a method performed by a user equipment and a user equipment, which can effectively perform radio link failure reporting under the DAPS mechanism in the LTE / NR system.

[0004] According to the present invention, a method executed by a user equipment UE is proposed, comprising: when a DAPS switching failure occurs during the UE's execution of a dual activation protocol stack DAPS switching, if a source base station radio link failure, i.e., a source base station RLF, is not detected, the UE falls back to the source base station link, and does not generate and save switching failure information for the DAPS switching failure in a link failure report; and when falling back to the source base station link, if the UE detects that a source base station RLF has occurred, the UE records and saves the link failure information for the source base station RLF in a link failure report.

[0005] Preferably, the falling back to the source base station link comprises: the source base station falls back to the used radio resource control RRC configuration and recovers the suspended signaling radio bearer of the source cell.

[0006] Preferably, the link failure report further includes: information indicating that the UE has just experienced the DAPS handover failure.

[0007] Preferably, the link failure report further includes: an identifier of a target cell of the DAPS handover, and / or information indicating failure of a random access procedure performed during the DAPS handover.

[0008] In addition, according to the present invention, a method performed by a user equipment UE is proposed, comprising: when a DAPS switching failure occurs during the UE's execution of a dual activation protocol stack DAPS switching, if a source base station wireless link failure, i.e., a source base station RLF, is not detected, the UE falls back to the source base station link, and generates and saves switching failure information for the DAPS switching failure in a link failure report; and when falling back to the source base station link, if the UE detects that a source base station RLF has occurred, the UE records and saves link failure information for the source base station RLF in the link failure report.

[0009] Preferably, the falling back to the source base station link comprises: the source base station falls back to the used radio resource control RRC configuration and recovers the suspended signaling radio bearer of the source cell.

[0010] Preferably, the link failure report further includes: information indicating that the source base station RLF occurs when the UE falls back to the source base station link after the DAPS switching fails.

[0011] In addition, according to the present invention, a method executed by a user equipment UE is proposed, comprising: the UE monitors that a source base station radio link failure, i.e., a source base station RLF, occurs during a dual activation protocol stack DAPS switching process; and if a DAPS switching failure occurs after the source base station RLF occurs, the UE generates and saves switching failure information for the DAPS switching failure in a link failure report, wherein the link failure report also includes link failure information for the source base station RLF.

[0012] Preferably, the link failure information for the source base station RLF includes one or more of the following: information indicating the time elapsed from the UE receiving the DAPS switching command to the occurrence of the source base station RLF; information indicating the cause of triggering the source base station RLF; and information indicating that the source base station RLF occurred during the process of executing the DAPS switching.

[0013] In addition, according to the present invention, a user equipment is proposed, comprising: a processor; and a memory storing instructions; wherein the instructions execute the above method when executed by the processor.

[0014] According to the present invention, the radio link failure report under the DAPS mechanism in the LTE / NR system can be effectively performed. Specifically, when a radio link failure (Radio Link Failure, RLF) of the source cell and / or RLF or DAPS handover failure (HandOver Failure, HOF) of the target cell occurs when the UE performs DAPS handover in the LTE / NR system, the failure-related information can be effectively recorded or reported. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] For a more complete understanding of the present invention and its advantages, reference will now be made to the following description taken in conjunction with the accompanying drawings, in which:

[0016] Figure 1 It is a schematic diagram that identifies the general switching process.

[0017] Figure 2 The diagram is a schematic diagram of a user plane protocol stack in a dual-active protocol stack configuration.

[0018] Figure 3 is a flowchart showing a method executed by a user equipment according to embodiment 1 of the present invention.

[0019] Figure 4 is a flowchart showing a method executed by a user equipment according to embodiment 2 of the present invention.

[0020] Figure 5 is a flowchart showing a method executed by a user equipment according to scenario 3.1 of embodiment 3 of the present invention.

[0021] Figure 6 is a flowchart showing a method executed by a user equipment according to scenario 3.2 of embodiment 3 of the present invention.

[0022] Figure 7 is a flowchart showing a method executed by a user equipment according to embodiment 4 of the present invention.

[0023] Figure 8 is a flowchart showing a method executed by a user equipment according to embodiment 5 of the present invention.

[0024] Fig. 9 is a flowchart showing a method executed by a user equipment according to embodiment 6 of the present invention.

[0025] Fig.10is a flowchart showing a method executed by a user equipment according to embodiment 7 of the present invention.

[0026] Fig.11 is a flowchart showing a method executed by a user equipment according to embodiment 8 of the present invention.

[0027] Fig.12 is a flowchart showing a method executed by a user equipment according to embodiment 9 of the present invention.

[0028] Fig.13 is a block diagram schematically showing a user equipment involved in the present invention. DETAILED DESCRIPTION

[0029] Other aspects, advantages and salient features of the present invention will become apparent to those skilled in the art from the following detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings. In the accompanying drawings, identical or similar structures are identified by identical or similar reference numerals.

[0030] In the present invention, the terms "include" and "contain" and their derivatives mean inclusion rather than limitation; the term "or" is inclusive, meaning and / or.

[0031] In this specification, the various embodiments described below for describing the principles of the present invention are merely illustrative and should not be interpreted in any way as limiting the scope of the disclosure. The following description with reference to the accompanying drawings is used to help fully understand the exemplary embodiments of the present invention as defined by the claims and their equivalents. The following description includes a variety of specific details to aid understanding, but these details should be considered to be merely exemplary. Therefore, it should be recognized by those of ordinary skill in the art that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the present invention. In addition, for the sake of clarity and brevity, descriptions of well-known functions and structures are omitted. In addition, throughout the accompanying drawings, the same reference numerals are used for similar functions and operations.

[0032] The following uses the Long Term Evolution (LTE) / NR mobile communication system and its subsequent evolution versions as example application environments to specifically describe multiple implementations of the present invention. However, it should be noted that the present invention is not limited to the following implementations, but is applicable to more other wireless communication systems. Unless otherwise specified, in the present invention, the concepts of cell and base station can be interchangeable; the LTE system is also used to refer to 5G and subsequent LTE systems (such as eLTE systems, or LTE systems that can be connected to the 5G core network), and LTE can be replaced by Evolved Universal Terrestrial Radio Access (E-UTRA) or Evolved Universal Terrestrial Radio Access Network E-UTRAN. In the present invention, handover refers to the change of the primary cell initiated by the network side, including the primary cell change between cells and the primary cell change within the cell, that is, the primary cell of the UE is changed from the source cell to the target cell, wherein the source cell and the target cell can be the same cell or different cells, and in this process, the key or security algorithm used for access layer security can also be updated or not updated accordingly. The security includes encryption and decryption and integrity protection. The source cell may also be referred to as a source base station, or a source beam, a source transmission point (Transmission point, TRP), a source primary cell (Primary Cell, PCell), and a source primary cell group MCG; the target cell may also be referred to as a target base station, or a target beam, a target transmission point, a target primary cell PCell, and a target cell group MCG. The source cell refers to the cell that serves the UE and is connected before the handover process is initiated, that is, the cell that sends an RRC message containing a handover command to the UE. The target cell refers to the cell that serves the UE and is connected to after the handover process is successfully completed, the cell indicated by the target cell identifier contained in the handover command, or the cell described as performing downlink synchronization and random access during the handover process. The handover command described in the present invention is used to trigger the UE to perform a handover, and in the NR system, it is an RRC reconfiguration message containing a synchronous reconfiguration (Reconfiguration with sync) information element, and further, it is an RRC reconfiguration message containing a synchronous reconfiguration (Reconfiguration with sync) information element for the master cell group (Master Cell Group, MCG). At this time, the handover may also be referred to as a synchronous reconfiguration of the MCG. In the LTE system, it is an RRC connection reconfiguration message including a mobility control information (MobilityControlInfo) information element.Among them, the synchronization reconfiguration information element or the mobile control information information element may include configuration information of the target cell, such as the target cell identifier, the target cell frequency, the public configuration of the target cell such as system information, the random access configuration used by the UE to access the target cell, the security parameter configuration of the UE in the target cell, the radio bearer configuration of the UE in the target cell, etc. For ease of description, the RRC reconfiguration message in the present invention is equivalent to the RRC connection reconfiguration message; similarly, its response message RRC reconfiguration completion message is equivalent to the RRC connection reconfiguration completion message. The handover command is equivalent to the RRC message containing the handover command, which refers to the RRC message or the configuration in the RRC message that triggers the UE to perform the handover. The handover configuration refers to all or part of the configuration in the handover command. Cancel, release, delete, clear and clear can be replaced. Execute, use and apply can be replaced. Configuration and reconfiguration can be replaced. Monitor and detect can be replaced. The RRC reestablishment message is equivalent to the RRC connection reestablishment message; similarly, its response message RRC reestablishment completion message is equivalent to the RRC connection reestablishment completion message.

[0033] The following describes the processes or concepts in the prior art to which the present invention relates.

[0034] Switching configuration in NR system:

[0035] In the NR system, the RRC reconfiguration message for the handover command carries the RRC configuration from the target base station, including but not limited to the following RRC configuration (see section 6.2.2 of 3GPP technical standard protocol 38.331 for details):

[0036] - Measurement configuration (measconfig information element): used to configure the intra-frequency, inter-frequency and inter-RT measurements performed by the UE, such as measurement object configuration, measurement reporting configuration, measurement gap configuration, etc.

[0037] -Cell group configuration (cellGroupConfig information element), used to configure the primary cell group or secondary cell group. Including the radio link control (Radio Link Control, RLC) bearer configuration (rlc-bearerToAddModList information element and rlc-bearerToreleaselist information element) corresponding to the data radio bearer / signaling radio bearer, medium access control (Medium Access Control, MAC) configuration (MAC-cellgroupconfig information element), physical layer configuration, secondary cell addition / modification / release configuration, special cell (Special cell, SpCell) configuration, etc. Among them, the sPCell configuration includes the cell index number, handover information (reconfigurationWithSync information element), radio link failure related timer and constant configuration, radio link detection (Radio Link Monitoring, RLM) configuration, special cell dedicated configuration, etc. Among them, the reconfigurationwithsync information element is similar to the mobile control information in the LTE system, and contains handover related information to achieve mobility. It includes serving cell configuration public information, UE's C-RNTI in the target cell, handover process monitoring timer T304 configuration, and random access dedicated configuration for the random access process to the target cell.

[0038] - Non-access stratum dedicated information (dedicatedInfoNASList information element).

[0039] -Radio bearer configuration (radiobearerConfig information element), used to configure the service data application protocol layer (Service Data Application Protocol, SDAP) and PDCP of the radio bearer DRB and / or SRB.

[0040] -Master key update configuration (masterKeyupdate information element).

[0041] The following describes the general switching process in the LTE / NR system. For details, see Figure 1 .

[0042] The user mobility in the connected state is mainly achieved through the handover process, which refers to the process of changing the serving cell (primary cell) of the UE in the RRC connected state. The handover process generally includes the following stages:

[0043] Phase 1: Measurement phase. The base station sends measurement configuration to the user equipment (UE); the UE measures the radio link corresponding to the serving cell or neighboring cell based on the measurement configuration. When the configured measurement reporting conditions are met, the UE sends a measurement report to the base station. The measurement phase is not mandatory, and the base station can also blindly switch the UE when there is no valid measurement report.

[0044] Phase 2: Handover preparation phase. The base station decides whether to trigger a handover for the UE based on the received measurement report and other factors such as the base station load. If it is determined that a handover is triggered for the UE, the source base station initiates the handover preparation process by sending a handover request message to the target base station. The target base station decides whether to accept the handover request for the UE based on factors such as the UE context in the handover request message and the available resources of the target base station. If accepted, the target base station replies with a handover confirmation message to the source base station, where the handover confirmation message contains an inter-node RRC message, namely the handover command.

[0045] Phase 3: Handover execution phase. The source base station sends the handover command to the UE and starts forwarding the UE's data to the target base station. The UE that receives the handover command immediately applies the configuration of the handover command to perform the handover, accesses the target base station through the random access process, and sends a confirmation message to the target base station. The random access process is not mandatory.

[0046] Phase 4: Handover completion phase. After the target base station confirms that the UE has successfully accessed, it sends a handover completion message to the source base station. The source base station can release the UE context stored thereon.

[0047] Dual Active Protocol Stack (DAPS) switching:

[0048] The DAPS switching introduced in version 16 refers to a switching process in which the UE maintains a connection with the source base station after receiving the RRC message for switching until the source base station is released after successfully executing the random access process to the target. During this process, for the bearer configured with DAPS, the UE continues to receive downlink data from the source base station until the source base station is released, and the user continues to send uplink data to the source base station until the random access process to the target base station is successfully completed. After the random access process to the target base station is completed, the MAC layer indicates to the upper layer that the random access process is completed. After receiving the indication, the RRC layer instructs the lower layer (such as the Packet Data Convergence Protocol (PDCP) layer) to perform uplink data changes and change the uplink path from the source base station to the target base station. When the PDCP layer is requested to change uplink data, the PDCP layer delivers the PDCP data protocol data unit (PDU) PDU to the RLC entity associated with the target base station, delivers the PDCP control PDU associated with the source base station to the RLC entity associated with the source base station, and delivers the PDCP control PDU associated with the target base station to the RLC entity associated with the target base station.

[0049] In the case of DAPS switching, after receiving the switching command, the UE establishes a MAC entity for the target base station. If a DRB is configured as a DAPS bearer, an RLC entity and a dedicated traffic channel (DTCH) logical channel associated with the target base station are established for the DRB, and the PDCP entity associated with the DAPS bearer is reconfigured as a DAPS PDCP entity. The DAPS PDCP entity has security and robustness header compression (ROHC) functions associated with the source base station and the target base station respectively in the PDCP entity, and the security and ROHC functions are associated with the corresponding RLC entities configured by the source base station and the target base station respectively. In the above manner, during the DAPS switching process, the UE simultaneously maintains the activation protocol stacks for the source base station and the target base station, see Figure 2 .

[0050] During the DAPS process, if the radio link of the source base station fails, the UE will suspend the transmission of DRBs of all source base stations, reset the MAC entity, and release the connection of the source base station. When the DAPS switch is successful, the UE receives the RRC reconfiguration message sent from the target base station, which carries the indication information for instructing the release of the source base station (such as the daps-SourceRelease information element). After receiving the indication, the UE executes the operation of releasing the source base station configuration and protocol stack, and falls back to the single activation protocol stack state that only maintains a connection with the target base station.

[0051] When the DAPS handover fails, that is, the T304 timer used to monitor the handover process times out, if the source base station does not detect a radio link failure, the UE returns to the connection with the source base station and informs the source base station of the DAPS handover failure without triggering the RRC connection re-establishment process. In the process of returning to the connection with the source base station, the UE falls back from the DAPS state to a single-activated protocol stack state that only communicates with the source base station. If the source base station also detects RLF or is in the RLF state when the DAPS handover fails, the UE triggers the RRC connection re-establishment process to recover the link.

[0052] In the following embodiments, the DAPS switching may be replaced by a switching process in which any DRB is configured as a DAPS bearer.

[0053] Radio Link Failure (RLF):

[0054] The UE considers that RLF has occurred when one of the following situations occurs: timer T310 used for RLF monitoring times out, timer T312 used for fast RLF monitoring times out, random access problem indication is received from the MAC layer, and indication is received from the RLC entity indicating that the maximum number of retransmissions has been reached. During DAPS switching, if the above timer, MAC entity and RLC are associated with the source base station MCG, it is considered that the source base station MCG RLF (referred to as source base station RLF) is monitored; if the above timer, MAC entity and RLC are associated with the target base station MCG, it is considered that the target base station MCG RLF is monitored. In the case of single connection or dual connection, if the above timer, MAC entity and RLC are associated with MCG, it is considered that MCG RLF is monitored. In dual connectivity (DC), the UE is configured with a secondary cell group (SCG). If the above timer, MAC entity and RLC are associated with SCG, it is considered that SCG RLF is monitored.

[0055] Handover Failure:

[0056] The judgment of handover failure is realized through the running status of timer T304. When the UE initiates the handover process and starts to execute the handover to the target base station, the timer T304 is started; when the handover process is successful, the timer T304 is stopped. The success of the handover process refers to the successful sending of the RRC message used to respond to the handover command, such as the RRC reconfiguration completion message, or the successful completion of the random access process to the target base station by the UE MAC layer; if T304 times out, the UE considers that the handover has failed and HOF has occurred. Subsequently, the UE restores the RRC connection by performing RRC re-establishment or falling back to the source base station connection when DAPS is configured. If there is no special explanation later, the link failure may refer to RLF or HOF, also known as connection failure.

[0057] Radio link failure reporting mechanism in existing mechanisms:

[0058] In the current LTE system and version 16 NR system, the UE will generate and save a radio link failure report (RLF report) when a link failure occurs. For example, the UE variable used to save the radio link failure report is VarRLF-Report. After restoring the connection with the network side (such as through the RRC re-establishment process or the RRC establishment process), the UE can inform the network side through an RRC message that there is an available radio link failure report (such as indicated by the rlf-InfoAvailable information element). For example, the UE can inform the network side that the UE has a saved and available radio link failure report in the RRC connection re-establishment process, in the RRC reconfiguration process, in the RRC setup complete message (RRCSetupComplete) in the RRC connection establishment process, or in the RRC recovery complete message (RRCResumeComplete) in the RRC connection recovery process. After receiving the indication, the network side may request the UE to report its saved radio link failure report through an RRC message (such as the rlf-ReportReq information element in the UEInformationRequest message to indicate the request). The UE will report the saved radio link failure report (rlf-Report information element in the UEInformationResponse message) to the network side in the response RRC message. The radio link failure report obtained by the network side is used for network optimization, such as network coverage and mobility robustness optimization. The radio link failure report may include: the measurement results of the available source cell and neighboring cell when the link fails, the location information, the primary cell identifier where the link failure occurs, the link failure type (such as RLF or HOF), the RLF reason, the time from link failure to reporting the radio link failure (timeSinceFailure information element), the time from the last receipt of the handover command to the execution of the handover process to the link failure (recorded as timeConnFailure information element), random access process information, etc. In addition, it also includes the cell identifier of the cell reconnected to the network after failure, such as the RRC re-establishment cell identifier, the RRC connection establishment cell identifier, etc. The random access process information is recorded in a link failure report when the cause of the link failure is a random access failure or the link failure is a handover failure.Generally speaking, the random access process information includes: the purpose or scenario of random access, the frequency domain starting information of message 1 (the offset between the lowest position of the physical random access channel PRACH transmission occasion in the frequency domain and the zeroth physical resource block of the uplink bandwidth part), the subcarrier spacing of the PRACH resource, and detailed information about each random access attempt during the random access process. The detailed information of each random access attempt includes the synchronization signal / physical broadcast channel block index value or channel state information reference signal index value used, the number of random access preambles sent on the beam corresponding to the index value, and whether each random access attempt has monitored competition and whether the measured signal quality (Reference Signal Received Power, RSRP) is higher than the configured threshold value. In the present invention, link failure report, radio link failure report, VarRLF-Report and connection failure information can be interchangeable. The existing mechanism only supports the UE to save one link failure report, that is, when a link failure occurs again, the UE will clear the saved link failure information related to the previous link failure (such as the information in the variable VarRLF-rpeort), and only record the link failure information related to the most recent link failure. The reason is that in the existing network, there are not many scenarios of multiple link failures occurring in succession, and between two link failures, the network side can always extract the information of the previous link failure from the UE side.

[0059] The present invention considers the following link failure scenarios:

[0060] Scenario 1: After receiving the handover command including DAPS configuration, the UE performs the DAPS handover process. Before DAPS is successful (i.e. T304 is in the running state), the source base station RLF is detected, and then the DAPS handover is successfully completed.

[0061] Scenario 2: After receiving the handover command containing the DAPS configuration, the UE performs the DAPS handover process. Then, T304 times out and a DAPS handover failure occurs. At this time, the source base station link does not detect a link failure, so the UE releases the target cell-related configuration and protocol stack, falls back to the source base station, and sends an RRC message (such as FailureInformation) containing a DAPS failure indication to the source base station, but then a link failure of the source base station occurs. In short, in scenario 1, the UE first experiences a DAPS handover failure, followed by a source cell link failure.

[0062] Scenario 3: After receiving the handover command containing the DAPS configuration, the UE performs the DAPS handover process. Before the DAPS is successful (i.e., T304 is in operation), the source base station RLF is detected, and then the DAPS handover fails due to T304 timeout. At this time, the UE initiates the RRC re-establishment process to recover the link. In short, in Scenario 3, the UE first experiences a source base station link failure, followed by a DAPS handover failure.

[0063] Scenario 4: After receiving the handover command containing the DAPS configuration, the UE performs the DAPS handover process, and then T304 times out and a DAPS handover failure occurs. At this time, the source base station link does not detect a link failure, so the UE releases the target cell-related configuration and protocol stack, successfully falls back to the source base station, and sends an RRC message containing a DAPS failure indication (such as FailureInformation) to the source base station.

[0064] Scenario 5: After receiving the handover command containing the DAPS configuration, the UE performs the DAPS handover process. Before the DAPS is successful (i.e. T304 is in operation), the source base station RLF is detected, and then the DAPS handover is successfully completed. However, the target base station RLF occurs soon after.

[0065] Scenario 6: After receiving the handover command including the DAPS configuration, the UE performs the DAPS handover process and the DAPS handover is successful. Before receiving the source link release indication from the base station, the source base station RLF is detected.

[0066] In the current mechanism, the UE does not record the corresponding link failure information of the source base station RLF that occurs during the DAPS switching process, that is, when the T304 timer is running, that is, when the source base station RLF occurs, the UE does not generate and save the corresponding information in the VarRLF-report. However, during the DAPS switching process, the failure information of the source base station RLF is also helpful for the network side to optimize the DAPS switching parameters. This is because the purpose of DAPS switching is to maintain data transmission to the source base station and the target base station at the same time during the switching process, thereby reducing data transmission delays, especially for services with relatively high latency requirements. Therefore, it is also very important to maintain the normal operation of the source base station link during the DAPS switching process. Therefore, how to record the source base station RLF information during the DAPS switching process is a problem that the present invention is concerned about. In addition, in the above-mentioned scenarios such as scenarios 2 and 3, the UE has two consecutive link failures, and the existing mechanism only supports the UE to record the most recent link failure, which makes the failure information of the previous link failure unable to be obtained by the network side, which is not conducive to the parameter optimization of DAPS switching, which is also a problem that the present invention is concerned about. The present invention provides a solution to the above problem through the following embodiments.

[0067] Embodiment 1:

[0068] Figure 3 is a flowchart showing a method executed by a user equipment according to embodiment 1 of the present invention.

[0069] This embodiment provides a method for reporting link failure information of a UE during DAPS switching. In this embodiment, when the source base station RLF is detected during the DAPS switching process, the UE generates and saves link failure information related to the source base station RLF. This embodiment is applicable to the above-mentioned scenarios where the source base station RLF occurs, such as scenarios 1 and 6.

[0070] like Figure 3 As shown, in step 301, the UE detects the RLF of the source base station.

[0071] As mentioned above, the UE may consider that an RLF of the source base station has occurred when one or more of the following situations occurs: timer T310 or T312 associated with the source base station for determining wireless link failure times out, a random access problem indication is received from the source base station MAC entity, and an indication is received from the source base station RLF layer to indicate that the maximum number of retransmissions has been reached.

[0072] In step 303, the UE saves the RLF information in a link failure report variable (such as VarRLF-Report). In step 303, the UE may also suspend all data radio bearers in the source base station, release the source base station connection, and so on.

[0073] The storing of the source base station RLF information in the link failure report includes one or more of the following:

[0074] - Clear the information contained in the link failure report variable;

[0075] -Set the failedPCellId field to the cell identifier or cell frequency, tracking area code, etc. of the source primary cell where the RLF is detected.

[0076] -Set the previousPCellId field to the cell identifier and tracking area code of the source primary cell that received the handover command;

[0077] -Set the timeConnFailure field to the time from when the switch command is received to when the link failure occurs;

[0078] -Set the connectionFailureType field to radio link failure;

[0079] -Set the c-RNTI field to the cell radio network temporary identifier C-RNTI used in the source primary cell;

[0080] -Set the link failure cause field rlf-cause to the cause that triggered the radio link failure;

[0081] -Contains a field for indicating that the RLF is a source base station link RLF that occurs during a DAPS switching process. The DAPS switching process refers to the running state of T304 when the UE is configured with any DAPS bearer and performs the switching process, or after T304 stops after the DAPS switching is successful but the source base station configuration and protocol stack have not been released. The successful switching means that the MAC layer successfully completes the random access process triggered by the switching. The source base station configuration and protocol stack have not been released yet refers to before the UE receives an RRC message for releasing the source base station. In one embodiment, the field is set to "1" or "TRUE".

[0082] - A field is included to indicate the identity of the target cell of the DAPS handover. The target cell identity may be a global cell identity or a tracking area identity, a physical cell identity and a carrier frequency, etc. Preferably, the field may also be used to indicate that the link failure is a source base station RLF that occurs during the DAPS handover.

[0083] -The once field is used to indicate whether the link failure occurs during the DAPS handover process that has not successfully accessed the target base station (i.e., T304 is running), or during the DAPS handover process that has successfully accessed the target base station but has not received the link release indication from the source base station. Alternatively, it can be described as, this field is used to indicate whether the link failure occurs during the running of T304.

[0084] Preferably, when T304 in step 301 is running, that is, the UE is in the DAPS switching process and has not successfully accessed the target base station, step 303 is executed.

[0085] Obviously, before step 301, the UE also receives a handover command including a DAPS configuration and performs a handover process. The UE performs the above operations when DAPS is configured. The DAPS configured by the UE can also be described as the UE is configured with any one or more DAPS bearers; or any one or more DRBs of the UE are configured with DAPS (such as identified by the daps-Config information element). The DAPS bearer refers to the bearer DRB being configured with an information element for indicating the daps configuration, such as the daps-config information element. Preferably, the daps-config information element is configured for each DRB separately.

[0086] Embodiment 2:

[0087] Figure 4 is a flowchart showing a method executed by a user equipment according to embodiment 2 of the present invention.

[0088] This embodiment provides a method for reporting link failure information of a UE during DAPS switching. In this embodiment, when the source base station RLF is detected during the DAPS switching process, similar to the existing mechanism, the UE does not generate and save the link failure information related to the source base station RLF, but directly includes the relevant failure information in the RRC message to indicate to the target base station. This embodiment is applicable to the above-mentioned scenarios where the source base station RLF occurs, such as scenarios 1 and 6.

[0089] like Figure 4 As shown, in step 401, the UE detects the RLF of the source base station.

[0090] As mentioned above, the UE may consider that an RLF of the source base station has occurred when one or more of the following situations occurs: timer T310 or T312 associated with the source base station for determining wireless link failure times out, a random access problem indication is received from the source base station MAC entity, and an indication is received from the source base station RLF layer to indicate that the maximum number of retransmissions has been reached.

[0091] In step 403, the UE sends an RRC message including source base station failure information (RLF information) to the target base station.

[0092] The RRC message may be an RRC reconfiguration complete message, such as an RRC reconfiguration complete message for responding to a handover command or an RRC reconfiguration complete message for responding to an RRC reconfiguration message including a source base station release indication, or may be other RRC messages.

[0093] The source base station failure information includes one or more of the following:

[0094] -Set fields such as the timeConnFailure field to the time from when the switch command is received to when the link failure occurs;

[0095] -Set the link failure cause field rlf-cause to the cause that triggered the radio link failure;

[0096] -Contains a field for indicating that the RLF is a source base station link RLF that occurs during a DAPS switching process. The DAPS switching process refers to the state in which T304 is running when the UE is configured with any DAPS bearer and the switching process is performed, or after T304 stops after the DAPS switching is successful but the source base station configuration and protocol stack have not yet been released. The successful switching means that the MAC layer successfully completes the random access process triggered by the switching. The source base station configuration and protocol stack have not yet been released refers to before the UE receives an RRC message for releasing the source base station. In one embodiment, if the field is set to "TRUE" or "1", it means that a source base station RLF occurs during the DAPS switching process.

[0097] Preferably, when T304 in step 401 is running, that is, the UE is in the DAPS handover process and has not successfully accessed the target base station, step 403 is executed.

[0098] Obviously, before step 401, the UE also includes receiving a handover command including a DAPS configuration and performing a handover process. The UE performs the above operations when DAPS is configured. The DAPS configured by the UE can also be described as the UE being configured with any one or more DAPS bearers; or any one or more DRBs of the UE being configured with DAPS (such as identified by the daps-Config information element). The DAPS bearer refers to the bearer DRB being configured with an information element for indicating the daps configuration, such as the daps-config information element. Preferably, the daps-config information element is configured for each DRB separately.

[0099] Embodiment 3:

[0100] This embodiment provides a method for reporting link failure information of UE during DAPS switching. In this embodiment, when the source base station RLF is monitored during the DAPS switching process, the UE generates and saves link failure information related to the source base station RLF; when a DAPS switching failure occurs, the UE also generates and saves link failure information related to the switching failure, but when the link failure information is generated and saved, the previous link failure information related to the source base station RLF is not cleared. That is to say, the UE is allowed to save the failure reports corresponding to two consecutive link failures respectively. This embodiment is applicable to the above-mentioned scenarios where the source base station RLF occurs, such as scenarios 2 and 3.

[0101] Scenario 3.1

[0102] Figure 5 is a flowchart showing a method executed by a user equipment according to scenario 3.1 of embodiment 3 of the present invention.

[0103] For the scenario where DAPS handover failure occurs first and then source base station RLF occurs, the UE performs the following steps to record and save link failure information. The field settings in the UE recording and saving link failure information are the same as the existing mechanism and are not repeated here.

[0104] In step 501, when a DAPS handover failure occurs, that is, T304 times out, the UE generates and saves the handover failure information (remembered as the first failure information) in the link failure report variable VarRLF-report. Preferably, the connection failure type field connectionFailureType in the link failure report is set to indicate that the type is a DAPS handover failure. Alternatively, the connection failure type field is set to handover failure hof.

[0105] In step 503, if the source primary cell does not detect RLF, the UE falls back to the source base station link and releases the configuration and protocol stack of the target base station. The falling back to the source base station link includes falling back to the RRC configuration used in the source base station and restoring the suspended signaling radio bearer of the source cell. The UE initiates the sending of a FailureInformation message to the source base station to fall back to the source base station link and inform the source base station that a DAPS handover failure has occurred.

[0106] In step 505, the UE detects that the source base station RLF has occurred. For example, due to the failure of sending the Failureinformation message, such as reaching the maximum number of RLF retransmissions. At this time, the UE does not clear the information of the previous link failure stored in the link failure report variable VarRLF-report (recorded as the first failure information here), but adds a new item to record and save the link failure information corresponding to the source base station RLF (recorded as the second failure information here). That is to say, after the occurrence of RLF, if the UE has just experienced a DAPS switching failure before the failure, the UE does not clear the first failure information stored in the link failure report variable VarRLF-report, but adds a new item to record and save the second failure information corresponding to this RLF. The UE has just experienced a DAPS switching failure before the failure. In one implementation method, the UE determines that the UE has just experienced a DAPS switching failure before the failure based on the saved first failure information. For example, if the UE has the first failure information recording the DAPS switching failure saved, or if the connection failure type is determined to be HOF or DAPS HOF in the saved first link failure information, the failedPCellId field is the cell identifier of the target primary cell during the previous DAPS switching, the previousPCellId field is the cell identifier of the current serving cell, or the value of the timeConnFailure field is less than a constant value, or the reestablishmentCellId is not included in the first failure information, the UE determines that a DAPS switching failure has just occurred before the failure. Alternatively, the UE may determine that a DAPS switching failure has just occurred before the failure based on whether a failure information message FailureInformation message has been sent. If the UE has sent a failure information message FailureInformation message (in the recent period before the link failure occurs), the UE believes that a DAPS switching failure has just occurred.

[0107] That is, clearing the first failure information stored in the link failure report variable VarRLF-report occurs when the UE determines that no DAPS handover failure occurs before the current link failure.

[0108] Scenario 3.2

[0109] Figure 6 is a flowchart showing a method executed by a user equipment according to scenario 3.2 of embodiment 3 of the present invention.

[0110] For the scenario where the source base station RLF occurs first and then the DAPS handover fails, the UE performs the following steps to record and save the link failure information. The field settings in the UE recording and saving the link failure information are the same as the existing mechanism and are not described here.

[0111] In step 601, when the UE detects that the source base station link RLF has occurred, the UE generates and saves the link failure information (referred to as the first failure information here) in the link failure report variable VarRLF-report. Preferably, the link failure information includes a field for indicating that the RLF is the source base station link RLF that occurred during the DAPS switching process. Preferably, the DAPS switching process refers to the T304 running state when the UE is configured with any DAPS bearer and performs the switching process.

[0112] In step 603, when the UE detects that a DAPS handover failure has occurred, that is, T304 has timed out, the UE generates and saves the handover failure information in the link failure report variable VarRLF-report. At this time, the UE does not clear the first failure saved in the link failure report variable VarRLF-report, but adds a new item to record and save the link failure information corresponding to the DAPS handover failure (referred to as the second failure information here). That is, after a DAPS handover failure occurs, if the UE has just experienced a source base station link failure RLF before the failure, the UE does not clear the first failure information saved in the link failure report variable VarRLF-report, but adds a new item to record and save the second failure information corresponding to the DAPS handover failure. The UE has just experienced a source base station RLF before the DAPS handover failure. In one implementation, the UE determines that the source base station RLF has just occurred before the DAPS handover failure based on the saved first failure information. For example, if the relevant field in the saved first link failure information indicates that the failedPCellId field is the cell identifier of the source primary cell at the time of this DAPS switching, or the previousPCellId field is the cell identifier of the source primary cell, or the reestablishmentCellId is not included in the first failure information, etc., the UE determines that the source base station RLF just occurred before the failure. Alternatively, the UE can directly determine that the source base station RLF has occurred by judging the current source base station link status, that is, if the source base station has detected RLF, it is determined that the source base station RLF just occurred before the DAPS switching failure.

[0113] That is, clearing the first failure information stored in the link failure report variable VarRLF-report occurs when the UE determines that no RLF of the source base station occurs before the current link failure.

[0114] Obviously, before step 501 or step 601, the UE also receives a handover command including a DAPS configuration and performs a handover process. The UE performs the above operations when DAPS is configured. The DAPS configured by the UE can also be described as the UE is configured with any one or more DAPS bearers; or any one or more DRBs of the UE are configured with DAPS (such as identified by the daps-Config information element). The DAPS bearer refers to the bearer DRB being configured with an information element for indicating the daps configuration, such as the daps-config information element. Preferably, the daps-config information element is configured for each DRB separately.

[0115] Optionally, in the above two situations, the UE restores the link with the network side by triggering RRC connection re-establishment after the link failure occurs. During the RRC re-establishment process, if a cell for re-establishment is selected, the UE includes a field for indicating the re-established cell identifier in the first failure information or the second failure information. Or the UE includes a field for indicating the re-established cell in both the first failure information and the second failure information. Optionally, the UE includes a field for indicating the re-established cell only in the failure information corresponding to the most recent link failure, that is, in the second failure information.

[0116] Example 4

[0117] Figure 7 is a flowchart showing a method executed by a user equipment according to embodiment 4 of the present invention.

[0118] This embodiment provides a method for reporting link failure information of UE during DAPS switching. In this embodiment, following the criteria of the existing mechanism, the UE is not allowed to save two failure reports corresponding to two consecutive link failures respectively, but if a continuous link failure occurs during DAPS switching, the UE will record the failure information corresponding to this RLF in the most recent RLF report according to the existing mechanism, and also include some failure information of the previous DAPS switching failure. This embodiment is applicable to scenario 2.

[0119] In the scenario where DAPS handover failure occurs first and then source base station RLF occurs, the UE performs the following steps to record and save link failure information. The field settings in the UE recording and saving link failure information are the same as the existing mechanism and are not repeated here.

[0120] like Figure 7As shown, in step 701, when a DAPS handover failure occurs, that is, T304 times out, if the source primary cell does not detect RLF, the UE falls back to the source base station link. Optionally, at this time, the UE does not generate and save the handover failure information in the link failure report variable VarRLF-report (recorded as the first failure information).

[0121] Specifically, if the source primary cell does not detect RLF, the UE falls back to the source base station link and releases the configuration and protocol stack of the target base station. The falling back to the source base station link includes falling back to the RRC configuration used in the source base station and restoring the suspended signaling radio bearer of the source cell. The UE initiates the sending of a FailureInformation message to the source base station to fall back to the source base station link and inform the source base station that a DAPS handover failure has occurred.

[0122] In step 703, the UE detects that the source base station RLF has occurred. For example, due to the failure of the Failureinformation message to be sent, such as reaching the maximum number of RLF retransmissions. The UE records and saves the link failure information corresponding to the source base station RLF in a link failure report variable such as VarRLF-Report. Optionally, if the UE records the first failure information in step 701, the UE clears the saved first failure information. In addition, the UE includes a field in the link failure information variable to indicate that the UE has just experienced a DAPS switching failure. Preferably, the UE includes the target cell identifier of the DAPS switching in the link failure information variable. Optionally, it also includes random access process information performed during the DAPS switching process. The "source base station" in this step is only referred to as a better description of the method. In fact, in step 701, the UE has released the configuration and protocol stack of the DAPS switching target base station and ended the switching state, so in step 703, the "source base station" may also be referred to as a serving base station, a current base station or a current MCG, etc.

[0123] When the UE has just experienced a DAPS handover failure before the RLF, the operation including the DAPS handover failure information in the above step 703 is performed. The UE has just experienced a DAPS handover failure before the RLF, which can be determined by the UE based on whether the failure information message FailureInformation message has been sent. If the UE has sent a failure information message FailureInformation message (a short time before the link failure occurs), the UE believes that a DAPS handover failure has just occurred. Alternatively, if the UE has performed a DAPS handover (a short time before the link failure RLF occurs) and a DAPS handover failure has occurred, the UE believes that a DAPS handover failure has just occurred. Alternatively, the UE determines based on the first failure information saved in step 701, for example, if the UE has a saved first failure information or if the UE saves the first failure information in step 701 and if the first failure information indicates that the UE has experienced a DAPS handover failure, and the previous PCellId field in the failure information indicates an identifier related to the cell where the RLF currently occurs, the UE believes that a DAPS handover failure has just occurred.

[0124] Optionally, the link failure report variable includes a field for indicating that the RLF is an RLF that occurs after a DAPS handover failure, or the RLF is a link failure that falls back to a source base station after a DAPS handover failure. Preferably, the field is a connection failure type field connectionFailureType.

[0125] Obviously, before step 701, the UE also includes receiving a handover command including a DAPS configuration and performing a handover process. The UE performs the above operations when DAPS is configured. The DAPS configured by the UE can also be described as the UE being configured with any one or more DAPS bearers; or any one or more DRBs of the UE being configured with DAPS (such as identified by the daps-Config information element). The DAPS bearer refers to the bearer DRB being configured with an information element for indicating the daps configuration, such as the daps-config information element. Preferably, the daps-config information element is configured for each DRB separately.

[0126] Example 5

[0127] Figure 8 is a flowchart showing a method executed by a user equipment according to embodiment 5 of the present invention.

[0128] This embodiment provides a method for reporting link failure information of UE during DAPS switching. In this embodiment, following the guidelines of the existing mechanism, the UE is not allowed to save two failure reports corresponding to two consecutive link failures respectively, but if a continuous link failure occurs during DAPS switching, the UE does not generate a new RLF report (VarRLF-Report) for the most recent link failure RLF, but adds the relevant failure information of this link failure RLF to the RLF report corresponding to the previous DAPS switching failure. This embodiment is applicable to scenario 2.

[0129] In the scenario where DAPS handover failure occurs first and then source base station RLF occurs, the UE performs the following steps to record and save link failure information. The field settings in the link failure information recorded and saved by the UE when DAPS handover fails are the same as the existing mechanism and are not repeated here.

[0130] like Figure 8 As shown, in step 801, when a DAPS switching failure occurs, that is, T304 times out, if the source primary cell does not detect RLF, the UE falls back to the source base station link. At this time, the UE generates and saves the switching failure information in the link failure report variable VarRLF-report (recorded as the first switching failure information).

[0131] Specifically, if the source primary cell does not detect RLF, the UE falls back to the source base station link and releases the configuration and protocol stack of the target base station. The falling back to the source base station link includes falling back to the RRC configuration used in the source base station and restoring the suspended signaling radio bearer of the source cell. The UE initiates the sending of a FailureInformation message to the source base station to fall back to the source base station link and inform the source base station that a DAPS handover failure has occurred.

[0132] In step 803, the UE detects that RLF of the source base station has occurred. For example, due to the unsuccessful sending of the Failureinformation message, such as reaching the maximum number of RLF retransmissions. The UE records the link failure information corresponding to the RLF of the source base station in the link failure report variable such as VarRLF-Report as follows: It includes a field to indicate that RLF has occurred when the UE falls back to the source base station link after the DAPS switching fails, or the fallback to the source base station link fails. Optionally, it includes a field indicating the measurement results of the primary cell and neighboring cell available when the RLF occurs. Optionally, it also includes a time field for indicating the time elapsed between the DAPS switching failure in step 801 and the RLF in step 803 of the UE, and optionally, it also includes a field for indicating the cause of the RLF. In this step, when RLF occurs, the UE does not clear the first failure information stored in the radio link failure report variable in step 801, but includes the above field in addition to the first failure information stored in the radio link failure report. The term "source base station" in this step is only for the purpose of better describing the method. In fact, in step 801, the UE has released the configuration and protocol stack of the DAPS switching target base station and ended the switching state. Therefore, in step 803, the "source base station" can also be referred to as the serving base station, the current base station or the current MCG, etc.

[0133] The link failure report variable is generated when the DAPS switching failure occurs in step 801, and includes relevant information of the DAPS switching failure; it is not a new link failure report item created in step 803.

[0134] Obviously, before step 801, the UE also includes receiving a handover command including a DAPS configuration and performing a handover process. The UE performs the above operations when DAPS is configured. The DAPS configured by the UE can also be described as the UE being configured with any one or more DAPS bearers; or any one or more DRBs of the UE being configured with DAPS (such as identified by the daps-Config information element). The DAPS bearer refers to the bearer DRB being configured with an information element for indicating the daps configuration, such as the daps-config information element. Preferably, the daps-config information element is configured for each DRB separately.

[0135] Example 6

[0136] Fig. 9 is a flowchart showing a method executed by a user equipment according to embodiment 6 of the present invention.

[0137] This embodiment provides a method for reporting link failure information of a UE during DAPS switching. In this embodiment, following the guidelines of the existing mechanism, the UE is not allowed to separately save two failure reports corresponding to two consecutive link failures, but if continuous link failures occur during DAPS switching, the UE does not generate a new RLF report (VarRLF-Report) for the most recent link failure RLF. This embodiment is applicable to scenario 2.

[0138] In the scenario where DAPS handover failure occurs first and then source base station RLF occurs, the UE performs the following steps to record and save link failure information. The field settings in the link failure information recorded and saved by the UE when DAPS handover fails are the same as the existing mechanism and are not repeated here.

[0139] like Fig. 9 As shown, in step 901, when a DAPS handover failure occurs, that is, T304 times out, if the source primary cell does not detect RLF, the UE falls back to the source base station link. At this time, the UE generates and saves the handover failure information in the link failure report variable VarRLF-report.

[0140] Specifically, if the source primary cell does not detect RLF, the UE falls back to the source base station link and releases the configuration and protocol stack of the target base station. The falling back to the source base station link includes falling back to the RRC configuration used in the source base station and restoring the suspended signaling radio bearer of the source cell. The UE initiates the sending of a FailureInformation message to the source base station to fall back to the source base station link and inform the source base station that a DAPS handover failure has occurred.

[0141] In step 903, the UE detects that a RLF of the source base station has occurred. For example, due to failure in sending the Failureinformation message, such as reaching the maximum number of RLF retransmissions. In this case (RLF occurs when the UE falls back to the source base station link after the DAPS handover fails, or the fallback to the source base station link fails), the UE does not generate a new link failure report for this RLF, nor does it modify or add information / fields in the saved link failure report variables such as VarRLF-Report.

[0142] Obviously, before step 901, the UE also includes receiving a handover command including a DAPS configuration and performing a handover process. The UE performs the above operations when DAPS is configured. The DAPS configured by the UE can also be described as the UE being configured with any one or more DAPS bearers; or any one or more DRBs of the UE being configured with DAPS (such as identified by the daps-Config information element). The DAPS bearer refers to the bearer DRB being configured with an information element for indicating the daps configuration, such as the daps-config information element. Preferably, the daps-config information element is configured for each DRB separately.

[0143] Example 7

[0144] Fig.10 is a flowchart showing a method executed by a user equipment according to embodiment 7 of the present invention.

[0145] This embodiment provides a method for reporting link failure information of UE during DAPS switching. In this embodiment, following the guidelines of the existing mechanism, the UE is not allowed to separately save two failure reports corresponding to two consecutive link failures. However, if a continuous link failure occurs during DAPS switching, the UE will record the failure information corresponding to this DAPS switching failure in the most recent RLF report in accordance with the existing mechanism, and also include some failure information of the previous source base station RLF. This embodiment is applicable to scenario 3.

[0146] In the scenario where the source base station RLF occurs first and then the DAPS handover fails, the UE performs the following steps to record and save the link failure information. The field settings in the UE recording and saving the link failure information are the same as the existing mechanism and are not repeated here.

[0147] like Fig.10 As shown, in step 1001, the UE detects the RLF of the source base station.

[0148] As mentioned above, the UE may consider that an RLF of the source base station has occurred when one or more of the following situations occurs: timer T310 or T312 associated with the source base station for determining wireless link failure times out, a random access problem indication is received from the source base station MAC entity, and an indication is received from the source base station RLF layer to indicate that the maximum number of retransmissions has been reached.

[0149] In step 1003, when a DAPS handover failure occurs, that is, T304 times out, the UE generates and saves the handover failure information in the link failure report variable VarRLF-report. In addition, the UE also includes the source base station RLF failure information in step 1001 in the variable. The source base station failure information includes one or more of the following:

[0150] -Set a field to the time from receiving the handover command to the occurrence of the source base station RLF link failure;

[0151] -Set another field to the cause of triggering the RLF of the source base station;

[0152] -Contains a field for indicating that a source base station link RLF has occurred during a DAPS handover process. The DAPS handover process refers to the T304 running state when the UE is configured with any DAPS bearer and performs a handover process. In one embodiment, if the field is set to "TRUE" or "1", it indicates that a source base station RLF has occurred during a DAPS handover process.

[0153] Obviously, before step 1001, the UE also includes receiving a handover command including a DAPS configuration and performing a handover process. The UE performs the above operations when DAPS is configured. The DAPS configured by the UE can also be described as the UE being configured with any one or more DAPS bearers; or any one or more DRBs of the UE being configured with DAPS (such as identified by the daps-Config information element). The DAPS bearer refers to the bearer DRB being configured with an information element for indicating the daps configuration, such as the daps-config information element. Preferably, the daps-config information element is configured for each DRB separately.

[0154] In another implementation manner, in step 1003, when the UE initiates the RRC connection re-establishment process, such as in its initialization phase, the UE includes the source base station failure information in a link failure report.

[0155] Example 8

[0156] Fig.11 is a flowchart showing a method executed by a user equipment according to embodiment 8 of the present invention.

[0157] This embodiment is applicable to scenario 4. In this embodiment, when a DAPS handover failure occurs, if the UE's source base station link does not detect RLF, the UE falls back to the source base station link, and the UE does not generate a corresponding radio link failure report for this DAPS handover failure event.

[0158] like Fig.11As shown, in step 1101, when a DAPS handover failure occurs, that is, T304 times out, if the source primary cell does not detect RLF, the UE does not generate and save the link failure report variable VarRLF-report corresponding to the handover failure. In other words, only when the source cell also detects RLF, the UE generates and saves the link failure report variable VarRLF-report corresponding to the handover failure.

[0159] In step 1103, if the source primary cell does not detect RLF, the UE falls back to the source base station link and releases the configuration and protocol stack of the target base station. The falling back to the source base station link includes falling back to the RRC configuration used in the source base station and restoring the suspended signaling radio bearer of the source cell. The UE initiates the sending of a FailureInformation message to the source base station to fall back to the source base station link and inform the source base station that a DAPS handover failure has occurred.

[0160] The failure information message FailureInformation message includes one or more of the following indication information: used to indicate that the failure is a DAPS handover failure; random access process information during the DAPS handover process; all available measurement results of one or more cells with the best measured quality, and the measurement does not include measurement of the source primary cell. Preferably, the one or more cells refer to cells associated with the configured measurement object (such as measOjectNR information element configuration).

[0161] Example 9

[0162] Fig.12 is a flowchart showing a method executed by a user equipment according to embodiment 9 of the present invention.

[0163] This embodiment proposes a method for a UE to report to a base station that more than one radio link failure report is available thereon.

[0164] like Fig.12As shown, in step 1201, if the link failure report variable (such as VarRLF-Report) on the UE has more than one available RLF or HOF failure information stored, the UE can include an indication information in the RRC message, and the indication information is used to indicate to the network side that there are more than one available RLF or HOF failure information stored on the UE. The RRC message may be an RRC establishment complete message, an RRC recovery complete message, an RRC re-establishment complete message, an RRC reconfiguration complete message, etc. Preferably, when the UE's registered public land mobile network (RPLMN) is included in the PLMN identifier list stored in the link failure report variable, the UE performs the above operation.

[0165] In step 1203, the UE receives a request indication contained in an RRC message from the base station, wherein the request indication is used to request the UE to report one or more stored RLF / HOF information. Preferably, the request indication information may indicate that the UE reports only one RLF / HOF-associated information; or may indicate that the UE reports all stored RLF / HOF-associated information. Preferably, the RRC message is a UE information request message UEInformationRequest.

[0166] In step 1205, the UE reports the stored information of one or more RLF / HOF associations to the base station through an RRC message. Preferably, if the request indication information in step 1203 indicates that the UE reports only one RLF / HOF associated information; then in step 1205, the UE reports only the failure information associated with the most recent link failure; or if the request in step 1203 indicates that the UE reports all stored RLF / HOF associated information, then the UE reports all stored RLF / HOF associated information to the base station. Alternatively, the UE always reports all stored RLF / HOF associated information to the base station.

[0167] The above RLF / HOF associated information refers to failure information associated with an RLF or HOF event.

[0168] [Modifications]

[0169] Next, use Fig.13 A user equipment as a variation example that can execute the method executed by the user equipment described in detail above of the present invention is described.

[0170] Fig.13 It is a block diagram showing a user equipment UE involved in the present invention.

[0171] like Fig.13As shown, the user equipment UE130 includes a processor 1301 and a memory 1302. The processor 1301 may include, for example, a microprocessor, a microcontroller, an embedded processor, etc. The memory 1302 may include, for example, a volatile memory (such as a random access memory RAM), a hard disk drive (HDD), a non-volatile memory (such as a flash memory), or other memories, etc. The memory 1302 stores program instructions. When the instructions are executed by the processor 1301, the above method performed by the user equipment described in detail in the present invention may be executed.

[0172] It is worth noting that different embodiments are not mutually exclusive solutions, that is, different embodiments are methods for different aspects of the problem described in the present invention, and they can work together in a system.

[0173] The method of the present invention and the related equipment have been described above in conjunction with the preferred embodiments. It will be appreciated by those skilled in the art that the method shown above is merely exemplary. The method of the present invention is not limited to the steps and sequence shown above. The base station and user equipment shown above may include more modules, for example, modules that may be developed or developed in the future and may be used for the base station, MME, or UE, etc. The various identifiers shown above are merely exemplary and not restrictive, and the present invention is not limited to the specific information elements used as examples of these identifiers. Those skilled in the art may make many changes and modifications based on the teachings of the illustrated embodiments.

[0174] The program running on the device according to the present invention can be a program that enables a computer to implement the functions of the embodiments of the present invention by controlling a central processing unit (CPU). The program or the information processed by the program can be temporarily stored in a volatile memory (such as a random access memory RAM), a hard disk drive (HDD), a non-volatile memory (such as a flash memory), or other memory systems.

[0175] The program for realizing the functions of various embodiments of the present invention can be recorded on a computer-readable recording medium. The corresponding functions can be realized by making a computer system read the program recorded on the recording medium and executing these programs. The so-called "computer system" herein can be a computer system embedded in the device, and can include an operating system or hardware (such as a peripheral device). "Computer-readable recording medium" can be a semiconductor recording medium, an optical recording medium, a magnetic recording medium, a recording medium of a short-term dynamic storage program, or any other recording medium that is computer-readable.

[0176] The various features or functional modules of the devices used in the above embodiments can be implemented or executed by circuits (e.g., single-chip or multi-chip integrated circuits). Circuits designed to perform the functions described in this specification may include general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination of the above devices. The general-purpose processor may be a microprocessor, or any existing processor, controller, microcontroller, or state machine. The above circuits may be digital circuits or analog circuits. In the case where new integrated circuit technologies have emerged to replace existing integrated circuits due to advances in semiconductor technology, one or more embodiments of the present invention may also be implemented using these new integrated circuit technologies.

[0177] In addition, the present invention is not limited to the above-mentioned embodiments. Although various examples of the embodiments have been described, the present invention is not limited thereto. Fixed or non-mobile electronic devices installed indoors or outdoors can be used as terminal devices or communication devices, such as AV equipment, kitchen equipment, cleaning equipment, air conditioners, office equipment, vending machines, and other household appliances.

[0178] As mentioned above, the embodiments of the present invention have been described in detail with reference to the accompanying drawings. However, the specific structure is not limited to the above embodiments, and the present invention also includes any design changes that do not deviate from the main purpose of the present invention. In addition, the present invention can be modified in various ways within the scope of the claims, and the embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. In addition, the components with the same effect described in the above embodiments can be replaced with each other.

Claims

1. A method performed by a user equipment, the method comprising: receiving a radio resource control (RRC) message, the radio resource control (RRC) message comprising a reconfigurationwithSync information element and one or more data radio bearer (DRB) configurations to be configured with a dual active protocol stack (DAPS) configuration, the RRC message being used to trigger a DAPS handover; Execute the DAPS switching and start the timer T304; When the timer T304 runs, a radio link failure RLF on the source primary cell is detected; as well as When the timer T304 times out, the handover failure information is stored in the RLF report, including: Setting the first field to the time from receiving the RRC message to detecting the RLF in the source primary cell when T304 is running; as well as The second field is set to the cause of triggering the RLF in the source primary cell.

2. A user equipment, comprising: processor; as well as Memory, storage instructions, The processor executes the instructions to: Receive a radio resource control RRC message, the radio resource control RRC message including a reconfigurationwithSync information element and a dual-active protocol stack to be used One or more data radio bearer (DRB) configurations configured by DAPS configuration, wherein the RRC message is used to trigger DAPS switching; Execute the DAPS switching and start the timer T304; When the timer T304 runs, detect a radio link failure RLF on the source primary cell; and When the timer T304 times out, the handover failure information is stored in the RLF report, including: Setting the first field to the time from receiving the RRC message to detecting the RLF in the source primary cell when T304 is running; and The second field is set to the cause of triggering the RLF in the source primary cell.

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