Method and apparatus for enhancement of SHR

Abstract

The invention relates to a method and apparatus for enhancement of successful handover reporting (SHR). One embodiment of the present disclosure provides a user equipment (UE) comprising: a transceiver; and a processor coupled with the transceiver and configured to: receive a configuration associated with a handover process in an unlicensed spectrum, where the configuration indicates one or more trigger conditions associated with a successful handover report of the handover process that has been successfully completed; and storing successful handover related information in the successful handover report in response to satisfaction of at least one of the one or more trigger conditions.

Description

Technical Field

[0001] The present disclosure relates to wireless communication technology, and more particularly, to a method and a device for enhancing a successful handover report (SHR). Background Art

[0002] When a user equipment (UE) moves among cells, or among radio coverage areas associated with different base stations (BSs), the UE needs to perform a handover procedure. In some scenarios, the UE may be triggered to generate an SHR associated with a successful handover, which may include a set of measurements collected during the handover phase, i.e., measurements at the time of handover triggering, measurements at the end of handover execution, measurements after successful handover execution, etc., and transmit the SHR to the network to help the network further improve mobility robustness optimization (MRO).

[0003] The NR-U feature was introduced in Release 16, and the UE can operate in an unlicensed spectrum. In an NR-U system, any type of transmission can be transmitted in an unlicensed spectrum. Before transmitting on an unlicensed spectrum, the UE or BS should perform a listen-before-talk (LBT) process and / or sense the wireless channel to ensure that the wireless channel is not occupied by other transmissions that may be generated by non-3GPP technologies (such as WiFi). According to the current triggering conditions of SHR, some SHRs may be triggered by channel occupancy problems rather than mobility problems, and these SHRs should be distinguished so that the network can perform appropriate actions, such as updating relevant configurations.

[0004] Therefore, the present disclosure proposes some solutions for enhancement of SHR. Summary of the invention

[0005] One embodiment of the present disclosure provides a UE, comprising: a transceiver; and a processor, which is coupled to the transceiver and configured to: receive a configuration associated with a switching process in an unlicensed spectrum, wherein the configuration indicates one or more trigger conditions associated with a successful switching report of the switching process that has been successfully completed; and in response to the satisfaction of at least one of the one or more trigger conditions, store information related to the successful switching in the successful switching report.

[0006] In some embodiments, the one or more trigger conditions include at least one of the following: the ratio between a first time period from the last handover execution until a successful LBT process with the target cell and a configuration value of timer T304 is lower than a first threshold; the ratio between a value of an elapsed time of one of timer T304, timer T310 or timer T312 and the configuration value of the one of timer T304, timer T310 or timer T312 is higher than a second threshold; the ratio between the first time period and the value of an elapsed time of timer T304 is lower than a third threshold; the ratio between a total number of uplink (UL) bandwidth parts (BWPs) in the target cell where a continuous LBT failure occurs and a total number of UL BWPs associated with a random access (RA) process in the target cell is lower than a fourth threshold; the second time period from the last handover execution until a successful LBT process with the source cell is lower than a fifth threshold; the total number of UL BWPs in the source cell where a continuous LBT failure occurs and a total number of UL BWPs in the source cell are lower than a fifth threshold. The ratio between the total number of BWPs is lower than a sixth threshold; or a radio link failure (RLF) in the source cell is not caused by an LBT failure, wherein the RLF occurs at the source cell during a dual active protocol stack (DAPS) switching process while timer T304 is running.

[0007] In some embodiments, the successful handover related information includes at least one of the following: an identifier of a UL BWP in a source cell in which the LBT process is successful; an identifier of a UL BWP in the source cell in which LBT fails in a physical (PHY) layer or a media access control (MAC) layer before the LBT process is successful; a total number of UL BWPs in the source cell in which LBT fails in the PHY layer or the MAC layer before the LBT process is successful; an identifier of a UL BWP in a target cell in which the LBT process is successful; an identifier of a UL BWP in the target cell in which LBT fails in the PHY layer or the MAC layer before the LBT process is successful; a total number of UL BWPs in the target cell in which LBT fails in the PHY layer or the MAC layer before the LBT process is successful. The total number of BWPs; the time period from the last handover execution until a successful LBT process with the target cell; the time period from the last handover execution until a successful LBT process with the source cell; the time period from the last handover execution until UL data transmission with the source cell; the time period from the last handover execution until a preamble transmission; the time period from the last handover execution until MSG3 transmission; the time period from the last handover execution until MSGA transmission; the time period from the successful LBT process with the target cell until the handover process has been successfully completed; the time period from the successful LBT process with the source cell until the handover process has been successfully completed; or an indication that the RLF in the source cell is not caused by an LBT failure, wherein the RLF occurs at the source cell during a DAPS handover process while timer T304 is running.

[0008] In some embodiments, when the first non-repetitive packet from the target cell during the DAPS switching process is received earlier than the last packet from the source cell during the DAPS switching process, the successful switching related information includes an interruption time having a zero value, or the successful switching related information does not include the interruption time.

[0009] In some embodiments, the interruption time includes at least one of the following: the interruption time of each DAPS bearer; the interruption time of each non-DAPS bearer; the interruption time elapsed from the last packet data convergence protocol (PDCP) protocol data unit (PDU) received from the DAPS bearer or non-DAPS bearer of the source cell until the first non-duplicate PDCP PDU received from the DAPS bearer or non-DAPS bearer of the target cell; the maximum interruption time among the interruption times of all DAPS bearers; the maximum interruption time among the interruption times of all non-DAPS bearers; the maximum interruption time among the interruption times of all DAPS bearers and non-DAPS bearers; the minimum interruption time among the interruption times of all DAPS bearers; the minimum interruption time among the interruption times of all non-DAPS bearers; the minimum interruption time among the interruption times of all DAPS bearers and non-DAPS bearers; the average interruption time among the interruption times of all DAPS bearers; the average interruption time among the interruption times of all non-DAPS bearers; or the average interruption time among the interruption times of all DAPS bearers and non-DAPS bearers.

[0010] In some embodiments, the interruption time is measured based on one of the following: the interruption time is measured from the last PDCP PDU received from the DAPS bearer or non-DAPS bearer of the source cell until the first non-repeated PDCP PDU received from the DAPS bearer or non-DAPS bearer of the target cell; the interruption time is measured per DAPS bearer, and for each DAPS bearer, the interruption time is measured from the last PDCP PDU received from the source cell of the DAPS bearer until the first non-repeated PDCP PDU received from the target cell of the DAPS bearer; or the interruption time is measured per bearer including all DAPS bearers and all non-DAPS bearers, and for each bearer, the interruption time is measured from the last PDCP PDU received from the source cell of the bearer until the first non-repeated PDCP PDU received from the target cell of the bearer.

[0011] In some embodiments, the processor is further configured to perform at least one of: transmitting an indication for storing successful switching related information in the successful switching report; receiving a request for successful switching related information in the successful switching report; or transmitting the successful switching report.

[0012] Another embodiment of the present disclosure provides a radio access network (RAN) node, comprising: a transceiver; and a processor, which is coupled to the transceiver and configured to: generate a configuration associated with a switching process in an unlicensed spectrum, wherein the configuration indicates one or more trigger conditions associated with a successful switching report of the switching process that has been successfully completed; and transmit the configuration associated with the switching process.

[0013] In some embodiments, in the case where the RAN node is a target node, and the one or more trigger conditions include at least one of the following: the ratio between a first time period from the last handover execution until a successful LBT process with the target cell and a configuration value of timer T304 is lower than a first threshold; the ratio between the value of the elapsed time of timer T304 and the configuration value of timer T304 is higher than a second threshold; the ratio between the first time period and the value of the elapsed time of timer T304 is lower than a third threshold; or the ratio between the total number of UL BWPs in the target cell in which persistent LBT failures occur and the total number of UL BWPs associated with the RA process in the target cell is lower than a fourth threshold.

[0014] In some embodiments, where the RAN node is a target node, the processor is further configured to: transmit the configuration associated with the handover process to a source node.

[0015] In some embodiments, where the RAN node is a target node, the processor is further configured to perform at least one of: receiving a successful handover report from the UE or a third RAN node; or modifying a configuration associated with the LBT based on the successful handover report.

[0016] In some embodiments, where the RAN node is a source node, the processor is further configured to: transmit the configuration associated with the handover procedure to a UE.

[0017] In some embodiments, where the RAN node is a source node, the processor is further configured to perform at least one of: receiving a successful switching report from the target RAN node or a third RAN node; or modifying a configuration associated with LBT based on the successful switching report.

[0018] In some embodiments, in the case where the RAN node is a source node, and the one or more trigger conditions include at least one of the following: the ratio between the value of the elapsed time of one of timer T310 or timer T312 and the configured value of the one of timer T310 or timer T312 is higher than a fifth threshold; the second time period from the last handover execution until the successful LBT process with the source cell is lower than a sixth threshold; the ratio between the total number of UL BWPs in the source cell where persistent LBT failures occur and the total number of UL BWPs of the source cell is lower than a seventh threshold; or the RLF in the source cell is not caused by an LBT failure, wherein the RLF occurs at the source cell during a DAPS handover process while timer T304 is running.

[0019] In some embodiments, the successful handover related information includes at least one of the following: an identifier of a UL BWP in a source cell in which the LBT process is successful; an identifier of a UL BWP in the source cell in which LBT fails in the PHY layer or the MAC layer before the LBT process is successful; a total number of UL BWPs in the source cell in which LBT fails in the PHY layer or the MAC layer before the LBT process is successful; an identifier of a UL BWP in a target cell in which the LBT process is successful; an identifier of a UL BWP in the target cell in which LBT fails in the PHY layer or the MAC layer before the LBT process is successful; a total number of UL BWPs in the target cell in which LBT fails in the PHY layer or the MAC layer before the LBT process is successful. The total number of BWPs; the time period from the last handover execution until a successful LBT process with the target cell; the time period from the last handover execution until a successful LBT process with the source cell; the time period from the last handover execution until UL data transmission with the source cell; the time period from the last handover execution until a preamble transmission; the time period from the last handover execution until MSG3 transmission; the time period from the last handover execution until MSGA transmission; the time period from the successful LBT process with the target cell until the handover process has been successfully completed; the time period from the successful LBT process with the source cell until the handover process has been successfully completed; or an indication that the RLF in the source cell is not caused by an LBT failure, wherein the RLF occurs at the source cell during a DAPS handover process while timer T304 is running.

[0020] In some embodiments, when the first non-repetitive packet from the target cell during the DAPS switching process is received earlier than the last packet from the source cell during the DAPS switching process, the successful switching related information includes an interruption time having a zero value, or the successful switching related information does not include the interruption time.

[0021] In some embodiments, the processor is further configured to: if the interruption time in the successful handover related information has a zero value or does not include an interruption time in the successful handover related information, maintain a current mobility configuration associated with a DAPS handover procedure.

[0022] In some embodiments, the interruption time includes at least one of the following: the interruption time of each DAPS bearer; the interruption time of each non-DAPS bearer; the interruption time from the last PDCP PDU received from the DAPS bearer or non-DAPS bearer of the source cell to the first non-duplicate PDCP PDU received from the DAPS bearer or non-DAPS bearer of the target cell; the maximum interruption time among the interruption times of all DAPS bearers; the maximum interruption time among the interruption times of all non-DAPS bearers; the maximum interruption time among the interruption times of all DAPS bearers and non-DAPS bearers; the minimum interruption time among the interruption times of all DAPS bearers; the minimum interruption time among the interruption times of all non-DAPS bearers; the minimum interruption time among the interruption times of all DAPS bearers and non-DAPS bearers; the average interruption time among the interruption times of all DAPS bears; the average interruption time among the interruption times of all non-DAPS bearers; or the average interruption time among the interruption times of all DAPS bearers and non-DAPS bearers.

[0023] In some embodiments, the interruption time is measured based on one of the following: the interruption time is measured from the last PDCP PDU received from the DAPS bearer or non-DAPS bearer of the source cell until the first non-repeated PDCP PDU received from the DAPS bearer or non-DAPS bearer of the target cell; the interruption time is measured per DAPS bearer, and for each DAPS bearer, the interruption time is measured from the last PDCP PDU received from the source cell of the DAPS bearer until the first non-repeated PDCP PDU received from the target cell of the DAPS bearer; or the interruption time is measured per bearer including all DAPS bearers and all non-DAPS bearers, and for each bearer, the interruption time is measured from the last PDCP PDU received from the source cell of the bearer until the first non-repeated PDCP PDU received from the target cell of the bearer.

[0024] Another embodiment of the present disclosure provides a method performed by a UE, comprising: receiving a configuration associated with a switching process in an unlicensed spectrum, wherein the configuration indicates one or more trigger conditions associated with a switching report of the switching process that has been successfully completed; and in response to the satisfaction of at least one of the one or more trigger conditions, storing information related to the successful switching in the successful switching report.

[0025] Another embodiment of the present disclosure provides a RAN node, comprising: generating a configuration associated with a switching process in an unlicensed spectrum, wherein the configuration indicates one or more trigger conditions associated with a successful switching report of the switching process that has been successfully completed; and transmitting the configuration associated with the switching process. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] To describe the manner in which the advantages and features of the present application can be obtained, the description of the present application is presented by reference to specific embodiments of the application illustrated in the accompanying drawings. These drawings depict only example embodiments of the present application and therefore should not be considered limiting of its scope.

[0027] Figure 1 A schematic diagram illustrating a wireless communication system according to some embodiments of the present disclosure.

[0028] Figure 2 A flow chart illustrating a switching process according to some embodiments of the present disclosure.

[0029] Figure 3 A method performed by a UE for enhancing SHR according to some embodiments of the present disclosure is described.

[0030] Figure 4 A method performed by a RAN node for enhancing SHR according to some embodiments of the present disclosure is described.

[0031] Figure 5 A simplified block diagram illustrating an exemplary apparatus according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0032] The detailed description of the accompanying drawings is intended as a description of the currently preferred embodiments of the present invention and is not intended to represent the only form in which the present invention can be practiced. It should be understood that the same or equivalent functions can be achieved by different embodiments intended to be included in the spirit and scope of the present invention.

[0033] Although the operations are depicted in a particular order in the drawings, those skilled in the art will readily recognize that such operations need not be performed in the particular order or sequential order as shown, or that all of the described operations need not be performed to achieve the desired result; one or more operations may sometimes be skipped. In addition, the drawings may schematically depict one or more example processes in the form of a flow chart. However, other operations not depicted may be incorporated into the schematically illustrated example processes. For example, one or more additional operations may be performed before, after, simultaneously with, or between any of the illustrated operations. In some cases, multitasking and parallel processing may be advantageous.

[0034] Figure 1 A wireless communication system according to an embodiment of the present disclosure is depicted.

[0035] like Figure 1 As shown in FIG. 1 , the wireless communication system includes UE 101, BS 102-A and base station 102-B. Figure 1 Although a specific number of UEs and BSs are depicted in FIG. 1 , those skilled in the art will recognize that any number of UEs and BSs may be included in a wireless communication system.

[0036] UE 101 may include a computing device, such as a desktop computer, a laptop computer, a personal digital assistant (PDA), a tablet computer, a smart TV (e.g., a TV connected to the Internet), a set-top box, a game console, a security system (including a security camera), a car computer, a network device (e.g., a router, a switch, and a modem), etc. According to an embodiment of the present disclosure, UE 101 may include a portable wireless communication device, a smart phone, a cellular phone, a flip phone, a device with a subscriber identity module, a personal computer, a selective call receiver, or any other device capable of sending and receiving communication signals on a wireless network. In some embodiments, UE 101 includes a wearable device, such as a smart watch, a fitness bracelet, an optical head-mounted display, etc. In addition, UE 101 may be referred to as a subscriber unit, a mobile device, a mobile station, a user, a terminal, a mobile terminal, a wireless terminal, a fixed terminal, a subscriber station, UE 101, a user terminal or a device, or other terms used in the art. UE 101 may communicate directly with a BS via an uplink (UL) communication signal.

[0037] BSs may be distributed throughout a geographic area. In some embodiments, a BS may also be referred to as an access point, access terminal, base station, base station, macro cell, Node B, 5G Node B (gNB), E-UTRAN Node B (eNB), BS, home Node B, relay node, device, or other terms used in the art. A BS is typically part of a radio access network, which may include one or more controllers communicatively coupled to one or more corresponding BSs.

[0038] The wireless communication system is compatible with any type of network capable of sending and receiving wireless communication signals. For example, the wireless communication system is compatible with a wireless communication network, a cellular telephone network, a network based on time division multiple access (TDMA), a network based on code division multiple access (CDMA), a network based on orthogonal frequency division multiple access (OFDMA), an LTE network, a network based on the third generation partnership project (3GPP), a 3GPP 5G network, a satellite communication network, a high altitude platform network, and / or other communication networks. It is considered that with the development of network architecture and new service scenarios, all embodiments in the present disclosure are also applicable to similar technical problems; and in addition, the terms stated in the present disclosure may be changed, which should not affect the principles of the present disclosure.

[0039] In one embodiment, the wireless communication system is compatible with NR of the 3GPP protocol, where the BS transmits on the DL using an orthogonal frequency division multiplexing (OFDM) modulation scheme, and the UE 101 transmits on the uplink using a single carrier frequency division multiple access (SC-FDMA) scheme or an OFDM scheme. However, more generally, the wireless communication system may implement some other open or proprietary communication protocols, such as WiMAX and other protocols.

[0040] In other embodiments, the BS may communicate using other communication protocols (e.g., the IEEE 802.11 family of wireless communication protocols). In addition, in some embodiments, the BS may communicate on a licensed spectrum, while in other embodiments, the BS may communicate on an unlicensed spectrum. The present disclosure is not intended to be limited to implementations of any particular wireless communication system architecture or protocol. In another embodiment, the BS may communicate with the UE 101 using a 3GPP 5G protocol.

[0041] like Figure 1 , UE 101 is currently served by BS 102-A and is moving towards BS 102-B. UE 101, BS 102-A, and BS 102-B may operate in a licensed spectrum or an unlicensed spectrum. In this scenario, the UE may need to perform a handover procedure from BS 102-A to BS 102-B. BS 102-A is considered a source node, a source RAN node, a source BS, a source gNB, a source eNB, etc. BS 102-B is considered a target node, a target RAN node, a target BS, a target gNB, a target eNB, etc.

[0042] Figure 2 A flow chart illustrating a switching process according to some embodiments of the present disclosure.

[0043] Figure 2 Including UE, source RAN node (which is in Figure 2 is marked as "source", for example, Figure 1 BS102-A in the target RAN node (which is in Figure 2 is marked as "target", for example, Figure 1 BS102-B in the BS) and access and mobility management function (AMF).

[0044] In step 200, mobility control information is provided by the AMF, i.e., the UE context within the source RAN node contains information about roaming and access restrictions, which is provided at connection establishment or at the last Tracking Area (TA) update.

[0045] In step 201, the source RAN node configures a UE measurement procedure, for example, transmits a configuration associated with a handover procedure to the UE, and the UE then reports according to the configured measurement procedure.

[0046] In step 202, the source RAN node decides to hand over the UE based on the measurement report and radio resource management (RRM) information from the UE.

[0047] In step 203, the source RAN node transmits a handover request message to the target RAN node, and the source RAN node also transmits a transparent RRC container with necessary information to prepare for the handover at the target side.

[0048] In step 204, the target RAN node performs admission control. If slice information is sent to the target RAN node, slice-aware admission control may be performed. If a protocol data unit (PDU) session is associated with an unsupported slice, the target RAN node may reject such a PDU session.

[0049] In step 205, the target RAN node prepares for the handover and sends a handover request confirmation to the source RAN node, which contains a transparent container to be sent as an RRC message to the UE to perform the handover. The target RAN node also indicates whether to accept the DAPS handover.

[0050] In step 206, the source RAN node triggers Uu handover by sending an RRCReconfiguration message containing information required to access the target cell to the UE.

[0051] In step 207, the UE detaches from the source cell and synchronizes with the target cell.

[0052] In step 208, the UE synchronizes with the target cell and completes the RRC handover procedure by sending a message called "RRCReconfigurationComplete" to the target RAN node. In case the handover procedure is a DAPS handover, the UE does not detach from the source cell upon receiving the "RRCReconfiguration" message. The UE, upon receiving an explicit release from the target RAN node, releases the source signaling radio bearer (SRB) resources, the security configuration of the source cell, and stops downlink or uplink reception or transmission with the source RAN node.

[0053] In step 209, in case of DAPS handover, the target RAN node sends a HANDOVERSUCCESS message to the source RAN node to notify the UE that it has successfully accessed the target cell.

[0054] DAPS switching can be used for Radio Link Control (RLC) Acknowledged Mode (AM) or RLC Unacknowledged Mode (RLC-UM) bearers.For DRBs configured with DAPS, the following principles additionally apply.

[0055] About downlink transmission:

[0056] - Upon allocation of a downlink PDCP SN by the source RAN node, the source RAN node starts scheduling downlink data on the source radio link and also starts forwarding downlink PDCP SDUs together with the allocated PDCP SN to the target RAN node.

[0057] -Maintain the hyperframe number (HFN) for the forwarded downlink SDU for security synchronization, where the PDCP SN is assigned by the source gNB. The source RAN node sends an EARLY STATUS TRANSFER message to convey the DL COUNT value indicating the PDCP SN and HFN of the first PDCP SDU forwarded by the source gNB to the target RAN node.

[0058] -After the SN allocation is switched to the target gNB, the HFN as well as the PDCP SN are maintained. The SN STATUS TRANSFER message indicates the next DL PDCP SN to be assigned to packets that do not yet have a PDCP sequence number, even for RLC-UM.

[0059] -During handover execution, the UE continues to receive downlink data from both the source and target RAN nodes until the source RAN node connection is released by an explicit release command from the target gNB.

[0060] The motivation of the DAPS handover procedure is to reduce the user plane (UP) interruption during the handover procedure, i.e. to achieve 0ms UP interruption time during the handover procedure. In order to enable the network to know whether the DAPS handover related parameters are properly set, the actual user plane interruption time during the DAPS handover procedure is introduced in the SHR of the DAPS handover procedure.

[0061] During the DAPS switching process, early data forwarding is performed, that is, the source node forwards the downlink PDCP service data unit (SDU) together with the assigned PDCP sequence number (SN) to the target node. Upon successful switching to the target node, the target node may transmit a DL packet to the UE (which may include a repeated DL PDCP PDU (that is, the corresponding DL PDCP SDU is received from the source node, and the target node performs PDCP processing on the received DL PDCP SDU, such as header compression, integrity protection or encryption), a non-duplicate DL PDCP PDU or both). The UE receives downlink data from both the source node and the target node until the source node connection is released by an explicit release command from the target node.

[0062] For DAPS handover procedures in licensed or unlicensed systems, the interruption time is the time of arrival of the last PDCP PDU received from the source cell (denoted as T for clarity). source ) and the measurement is started at the time of arrival of the first non-duplicate PDCP PDU received from the target cell (denoted as T for clarity). target ) ends. The interruption time value can be obtained by (T target -T source However, there is a situation where the UE receives the first non-repetitive packet from the target cell earlier than the last packet from the source cell, that is, T target Earlier than T source Based on the storage or recording principle of the interruption time, the interruption time included in the SHR will be lower than zero, which is not a valid value. The network may not understand the meaning of the invalid value. The present disclosure proposes some solutions for solving this problem:

[0063] Solution 1

[0064] Solution 1 can be applied to systems including both unlicensed NR-U systems and NR licensed systems.

[0065] Solution 1-1: In T target Earlier than T source In this case, the interruption time is set to "zero".

[0066] After the UE detects the reception of the first non-duplicate packet from the target cell (i.e., T target) is earlier than the reception of the last packet from the source cell (i.e., T source ), the UE may set or store (or log, record, etc., hereinafter "store", "record" or "log" may be used interchangeably as appropriate) the interruption time in the SHR to "zero". At the network side, since the interruption time included in the SHR is "zero", the network (e.g., target node, source node, etc.) understands the goal of achieving 0ms UP interruption time in this DAPS switching process, and there is no need to modify the DAPS switching related mobility parameters. In other words, the network may maintain the current DAPS switching related mobility parameters after the SHR-based MRO analysis.

[0067] In this solution, the outage time included in the SHR can be zero or above zero, and the network can understand the meaning of the value of the outage time, and the problem is solved.

[0068] Solution 1-2: In T target Earlier than T source Alternatively, the interruption time is included in the SHR only if the last PDCP PDU received from the source cell of the DAPS handover is earlier than the first non-duplicate PDCP PDU received from the target cell of the DAPS handover.

[0069] After the UE detects the reception of the first non-duplicate packet from the target cell (i.e., T target ) is earlier than the reception of the last packet from the source cell (i.e., T source ), the UE does not store the interruption time in the SHR. That is, after the UE receives the last packet from the source cell (i.e., T source ) is later than receiving the first non-duplicate packet from the target cell (ie, T target ), the UE may not include the interruption time in the SHR.

[0070] For the UE to simultaneously receive the last packet from the source cell (i.e., T source ) and receiving the first non-duplicate packet from the target cell (ie, T target ), that is, T source =T target , the interruption time may be zero, and the UE may include the interruption time with a value of "zero" in the SHR as in solution 1-1. Alternatively, the UE may not include the interruption time in the SHR.

[0071] At the network side, when there is no interruption time in the SHR, the network understands the goal of achieving 0ms UP interruption time in this DAPS switching process, and does not need to modify the DAPS switching related mobility parameters. In other words, the network can maintain the current DAPS switching related mobility parameters after the MRO analysis based on the SHR.

[0072] In this solution, the outage time included in the SHR may be non-existent, zero, or may be a value greater than zero, and the network understands the meaning of the above conditions, i.e., the outage time is non-existent, zero, or greater than zero, and the problem is solved.

[0073] Based on Solution 1, the interruption time during the DAPS HO process can be appropriately stored or reported in the SHR. Another question is what is the granularity of the interruption time; this disclosure proposes some solutions to solve this problem:

[0074] Solution 2

[0075] Solution 2 may be applied to systems including both unlicensed NR-U systems and NR licensed systems. Solution 2 may be applied to a situation where the first non-duplicate packet from the target cell during a DAPS handover procedure is received earlier than the last packet from the source cell during the DAPS handover procedure, or the first non-duplicate packet from the target cell during a DAPS handover procedure is received later than the last packet from the source cell during the DAPS handover procedure, or the first non-duplicate packet from the target cell during a DAPS handover procedure is received simultaneously with the last packet from the source cell during the DAPS handover procedure.

[0076] DAPS handover is configured per DRB for UE, which means that DAPSDRB requires 0ms UP interruption time, but the rest do not. However, based on the current calculation of interruption time, the granularity of interruption time included in SHR is unclear.

[0077] Solution 2-1: The outage time is measured per DAPS bearer.

[0078] During DAPS switching, several DAPS bearers can be configured, for example, N DAPS DAPS bearers. For each DAPS bearer, the interruption time may be measured from the last PDCP PDU received from the source cell of the DAPS bearer until the first non-repeated PDCP PDU received from the target cell of the DAPS bearer. The number of values ​​of the interruption time stored or reported by the UE may be N DAPS , in other words, there may be N DAPS interruption time values, each interruption time value for N DAPSAlternatively, the number of values ​​of the interruption time stored or reported by the UE may be one, such as a maximum value, a minimum value, or an average value of the interruption time. The UE may store at least one of the following in the SHR:

[0079] - The interruption time of each DAPS bearer;

[0080] -N carried by all DAPS DAPS The maximum interruption time among the interruption times;

[0081] -N carried by all DAPS DAPS the minimum interruption time among the interruption times; or

[0082] -N carried by all DAPS DAPS The average interruption time among the interruption times.

[0083] Solution 2-2: The outage time is measured per bearer.

[0084] During DAPS switching, a number of DAPS bearers and a number of non-DAPS bearers may be configured as, for example, N DAPS DAPS bearers and N non-DAPS non-DAPS bearers. DAPS DAPS bearers and N non-DAPS For each of the non-DAPS bearers, the interruption time may be measured from the last PDCP PDU received by the self-bearing source cell until the first non-duplicate PDCP PDU received by the self-bearing target cell.

[0085] The total number of values ​​of outage time stored or reported by the UE may be a total (N DAPS +N non-DAPS ) interruption times, in other words, there may be (N DAPS +N non-DAPS ) interruption time values, each interruption time value for N DAPS DAPS bearers and N non-DAPS The UE may store at least one of the following in the SHR:

[0086] - The interruption time of each DAPS bearer;

[0087] - The outage time of each non-DAPS bearer;

[0088] -The maximum interruption time among the interruption times of all DAPS bearers, that is, N of all DAPS bearers DAPS The maximum interruption time among the interruption times;

[0089] -The maximum outage time among all non-DAPS bearer outage times, that is, N of all non-DAPS bearers non-DAPS The maximum interruption time among the interruption times;

[0090] - The maximum interruption time among the interruption times of all DAPS bearers and non-DAPS bearers, that is, N of all DAPS bearers DAPS outage time and all non-DAPS bearer N non-DAPS The maximum interruption time among the interruption times;

[0091] -The minimum interruption time among the interruption times of all DAPS bearers, that is, N of all DAPS bearers DAPS The minimum interruption time among the interruption times;

[0092] -The minimum interruption time among the interruption times of all non-DAPS bearers, that is, N of all non-DAPS bearers non-DAPS The minimum interruption time among the interruption times;

[0093] -The minimum interruption time among the interruption times of all DAPS bearers and non-DAPS bearers, that is, N of all DAPS bearers DAPS outage time and all non-DAPS bearer N non-DAPS The minimum interruption time among the interruption times;

[0094] - The average outage time among the outage times of all DAPS bearers, i.e., N of all DAPS bearers DAPS The average interruption time among the interruption times;

[0095] - The average outage time among all non-DAPS bearer outage times, i.e., N of all non-DAPS bearers non-DAPS the average duration of outages among the outages; or

[0096] - The average outage time among all DAPS bearers and non-DAPS bearers, that is, N of all DAPS bearers DAPS outage time and all non-DAPS bearer N non-DAPS The average interruption time among the interruption times.

[0097] Solution 2-3: The interruption time is measured from the last PDCP PDU received from the source cell of the DAPS bearer or non-DAPS bearer until the first non-repeated PDCP PDU received from the target cell of the DAPS bearer or non-DAPS bearer, and then the UE stores the interruption time in the SHR. In this solution, the number of values ​​of the interruption time stored or reported by the UE is only one.

[0098] In some cases, when both Solution 1 and Solution 2 are applied, and the reception of the first non-duplicate packet from the target cell (ie, T target ) is earlier than the reception of the last packet from the source cell (i.e., T source ), that is, the UE may determine the interruption time based on solution 1, that is, the interruption time may not exist, may be zero or a value greater than zero.

[0099] The MRO function in NR can be enhanced by reporting failure events observed during a successful handover from a source Next Generation Radio Access Network (NG-RAN) to a target NG-RAN to provide more robust mobility. A solution for enhancing the MRO function is to configure the UE to compile a report associated with a successful handover, which includes a set of measurements collected during the handover process, i.e., measurements at the time of handover triggering, measurements at the end of handover execution, or measurements after successful handover execution, etc. The UE can be configured with one or more trigger conditions to generate an SHR, so the SHR can be when at least one trigger condition is met. The trigger condition may include:

[0100] - the ratio between the value of the elapsed time of the timer T310 and the configured value of the timer T310 is greater than a threshold value (ie, thresholdPercentageT310);

[0101] - a ratio between the value of the elapsed time of the timer T312 associated with the measurement object of the target cell and the configured value of the timer T312 is greater than a threshold value (ie, thresholdPercentageT312);

[0102] - the ratio between the value of the elapsed time of timer T304 and the configured value of timer T304 is greater than a threshold value (ie, thresholdPercentageT304); or

[0103] - For DAPS handover procedure, RLF occurs in the source cell before a successful handover procedure.

[0104] In unlicensed spectrum, before performing any transmission during a normal handover process, a DAPS handover process, or a CHO handover process, both the UE and the BS should perform an LBT process and sense the wireless channel in order to ensure that the spectrum is not occupied by other transmissions that may be generated by non-3GPP technologies such as WiFi. In addition, new types of measurements representing RSSI and channel occupancy have been introduced to reflect the characteristics of unlicensed channels.

[0105] Regarding the LBT failure detection and recovery process, the MAC entity may be configured with a persistent LBT failure recovery process by the RRC. For UL transmission, persistent LBT failure is detected in the MAC entity per UL BWP by counting LBT failure indications received from a lower layer (i.e., the PHY layer). For example, the UE may perform LBT in a BWP, and if the number of LBT failure indications from the physical layer exceeds a maximum value (which may be represented as: lbt-FailureInstanceMaxCount) within a valid time (which may be represented as lbt-FailureDetectionTimer), the UE determines that a persistent LBT failure has occurred in this BWP or MAC layer. If a persistent LBT failure occurs in all UL BWPs configured with a physical random access channel (PRACH) opportunity, the MAC entity may indicate to the upper layer (i.e., the RRC layer) that an LBT failure has occurred.

[0106] RRC configures the following parameters in lbt-FailureRecoveryConfig: lbt-FailureInstanceMaxCount for continuous LBT failure detection; and lbt-FailureDetectionTimer for continuous LBT failure detection.

[0107] The following UE variables are used in the ongoing LBT failure detection process:

[0108] LBT_COUNTER (per serving cell): Counter for LBT failure indication, which is initially set to 0.

[0109] For each activated serving cell configured with lbt-FailureRecoveryConfig, the MAC entity shall perform the following steps:

[0110] 1> If LBT failure indication has been received from lower layers:

[0111] 2> Start or restart lbt-FailureDetectionTimer;

[0112] 2>Increment LBT_COUNTER by 1;

[0113] 2>If LBT_COUNTER>=lbt-FailureInstanceMaxCount:

[0114] 3> Triggering continuous LBT failure of active UL BWP in this serving cell;

[0115] 3> If the serving cell is SpCell:

[0116] 4> If persistent LBT failure has been triggered in all UL BWPs configured with PRACH opportunities on the same carrier in this serving cell:

[0117] 5> Indicate continuous LBT failure to the upper layer

[0118] 4> Otherwise:

[0119] 5> Stop any ongoing random access process in this serving cell;

[0120] 5> Switch the active UL BWP to a UL BWP on the same carrier in this serving cell, which is configured with a PRACH opportunity and for which a persistent LBT failure has not been triggered;

[0121] 5>Start random access process.

[0122] As mentioned above, SHR can be triggered by one or more trigger conditions. In the NR-U system, SHR can also be applied to successful handovers that are close to failure, and similar principles can be applied. In the case of a successful handover that is close to failure, SHR is triggered and reported to allow the network to detect or analyze radio link problems during the handover process, and thus to modify handover related parameters, such as reference signal received power (RSRP) threshold, reference signal received quality (RSRQ) threshold, signal to interference plus noise ratio (SINR) threshold for triggering handover.

[0123] The present disclosure proposes some solutions for triggering SHR in the NR-U system. Specifically, the present disclosure introduces some new triggering conditions in NR-U to exclude the situation where SHR is triggered due to channel occupancy problems.

[0124] Solution 3-1:

[0125] This solution can be applied to a normal handover procedure, a DAPS handover procedure, or a CHO procedure in an NR-U system, where at least one of the following triggering conditions for SHR in NR-U can be configured:

[0126] Trigger condition 1: When the ratio (labeled as ratio1 for clarity) is lower than the threshold (labeled as threshold1 for clarity), SHR is triggered. The ratio (ie, ratio1) can be determined based on the following two time periods P1 and P2, which are defined as follows:

[0127] - P1: the time period from the last handover execution until one of the following events occurs with the target cell: a successful LBT procedure, a preamble transmission, a MSG3 transmission in a 4-step RA procedure, or a MSGA transmission in a 2-step RA procedure; and

[0128] - P2: The configuration value of timer T304, ie it is included in the RRC reconfiguration message for handover.

[0129] The ratio (ie, ratio1) can be calculated by the following formula (1):

[0130]

[0131] In summary, when ratio1 is lower than threshold1, SHR is triggered. The threshold (i.e., threshold1) may be represented as: thresholdPercentage1forNR-U and may be configured by the target node. Trigger condition 1 may be generated by the target node and may be transmitted from the target node to the source node. For example, the value of threshold1 of trigger condition 1 may be, for example, Figure 2 The source node may then transmit the handover request confirmation message in step 205 as shown in FIG. Figure 2 In step 206 shown in FIG. 1 , a threshold value (ie, threshold1) is sent to the UE in an RRC reconfiguration message for handover.

[0132] Trigger condition 2: When the ratio (labeled as ratio2 for clarity) is greater than the threshold (labeled as threshold2 for clarity), SHR is triggered. The ratio (i.e., ratio2) can be determined based on the following two time periods P3 and P4, which are defined as follows:

[0133] - P3: the elapsed time of one of the following timers: timer T304, timer T310 or timer T312; and

[0134] - P4: The configuration value of the same timer as P3 (ie, timer T304, timer T310 or timer T312), ie, it is included in the RRC reconfiguration message.

[0135] The ratio (ie, ratio2) can be calculated by the following formula (2):

[0136]

[0137] It should be noted that in formula (2), P3 and P4 are related to the same timer, for example, when P3 is related to the elapsed time of timer T310, and P4 is also related to the configured value of timer T310. For example, trigger condition 2 may be that the ratio between the value of the elapsed time of timer T310 and the configured value of timer T310 is greater than threshold2 (i.e., thresholdPercentageT310), or the ratio between the value of the elapsed time of timer T312 associated with the measurement object of the target cell and the configured value of timer T312 is greater than threshold2 (i.e., thresholdPercentageT312), or the ratio between the value of the elapsed time of timer T304 and the configured value of timer T304 is greater than threshold2 (i.e., thresholdPercentageT314).

[0138] In summary, when ratio2 is greater than threshold2, SHR is triggered. In the case where trigger condition 2 is related to timer T304, trigger condition 2 is generated by the target node and transmitted to the source node, and then trigger condition 2 can be transmitted from the source node to the UE. For example, the value of threshold2 can be as follows: Figure 2 In step 206 shown in FIG. 1 , the threshold 2 is transmitted from the target node to the source node, and is transmitted from the source node to the UE in the RRCReconfiguration message. In the case where the trigger condition 2 is related to the timer T310 or the timer T312, it may be generated by the source node and may be transmitted from the source node to the UE. For example, the value of threshold 2 may be as shown in FIG. Figure 2 In step 206 shown in FIG. 1 , the RRCReconfiguration message is transmitted.

[0139] Trigger condition 3: When the ratio (labeled as ratio3 for clarity) is lower than the threshold (labeled as threshold3 for clarity), SHR is triggered. The ratio (i.e., ratio3) can be determined based on the following two time periods P1 and P5, which are defined as follows:

[0140] - P1: the same parameters as in trigger condition 1, which are: the time period from the last handover execution until the time when one of the following events occurs: a successful LBT procedure, a preamble transmission, a MSG3 transmission in a 4-step RA procedure, or a MSGA transmission in a 2-step RA procedure; and

[0141] - P5: Elapsed time of timer T304.

[0142] The ratio (ie, ratio3) can be calculated by the following formula (3):

[0143]

[0144] In summary, when ratio3 is lower than threshold3, SHR is triggered. The threshold (i.e., threshold3) may also be expressed as: thresholdPercentage2forNR-U, and may be configured by the target node and may be transmitted from the target node to the source node. For example, the value of threshold3 of trigger condition 3 may be, for example, Figure 2 The source node may then transmit the handover request confirmation message in step 205 as shown in FIG. Figure 2 In step 206 shown in FIG. 1 , a threshold value (ie, threshold3) is sent to the UE in an RRC reconfiguration message for handover.

[0145] When at least one of the above trigger conditions 1 to 3 is met, the UE may store the following in the SHR, and the UE may report the SHR to the network (e.g., the target node or the third node to which the UE is connected after a successful handover). The SHR may include at least one of the following:

[0146] - SHR cause associated with the triggering condition;

[0147] - The identifier of the UL BWP in the target cell where the LBT procedure was successful;

[0148] - an identifier of the UL BWP (or each UL BWP) in the target cell for which LBT failed in the PHY layer or MAC layer (if any) before the LBT procedure succeeded. The identifier may not be present in the case where there was no LBT failure in the PHY layer or MAC layer before the LBT procedure succeeded, or in the case where LBT with the target cell succeeded on the UL BWP of the target cell on the first RACH attempt;

[0149] - the total number of UL BWPs in the target cell where LBT failed in the PHY layer or MAC layer (if any) before the LBT procedure succeeded. In the case where there is no LBT failure in the PHY layer or MAC layer before the LBT procedure succeeded, or in the case where LBT succeeded with the target cell on the UL BWP of the target cell on the first RACH attempt, the total number of UL BWPs may be zero or non-existent;

[0150] - The time period from the last handover execution until a successful LBT procedure with the target cell;

[0151] - the time period from the last handover execution until one of the following events occurs: preamble transmission, MSG3 transmission in a 4-step RA procedure, or MSGA transmission in a 2-step RA procedure;

[0152] - the time period that has passed since a successful LBT procedure with the target cell until the handover procedure has been successfully completed; or

[0153] - The period of time that elapses from when the handover procedure has been successfully completed until the UE reports the SHR.

[0154] Trigger condition 4: When the ratio (labeled as ratio4 for clarity) is lower than the threshold (labeled as threshold4 for clarity), SHR is triggered. The ratio (ie, ratio4) can be determined based on the following two numbers associated with the UL BWP in the target cell:

[0155] - N1: the total number of UL BWPs in the target cell where persistent LBT failures occurred, for example in the MAC layer; and

[0156] - N2: The total number of UL BWPs in the target cell configured with a random access channel (RACH) configuration. That is, the total number of UL BWPs in which the UE can perform a RACH procedure in the target cell, or the total number of UL BWPs configured by the network for a handover procedure, for example, the total number of UL BWPs configured with a RACH configuration for a RACH procedure in the target cell.

[0157] The ratio (ie, ratio4) can be calculated by the following formula (4):

[0158]

[0159] For example, assume that four UL BWPs in the target cell are configured with RACH configuration. The UE may perform an LBT procedure on the UL BWP before performing a RACH procedure on the UL BWP, and before the successful LBT procedure, a continuous LBT failure on two UL BWPs may have been detected, then

[0160] In summary, when ratio4 is lower than threshold4, SHR is triggered. The threshold (i.e., threshold4) may also be expressed as: numberPercentageforNR-U and may be configured by the target node. The threshold (i.e., threshold4) may be transmitted from the target node to the source node. The source node may then send threshold4 to the UE in an RRC reconfiguration message for handover.

[0161] When the above trigger condition 4 is met, the UE may store the following in the SHR, and the UE may report the SHR to the network (e.g., the target node or the third node to which the UE is connected after a successful handover). The SHR may include at least one of the following:

[0162] - SHR cause associated with the triggering condition;

[0163] -The total number of UL BWPs in the target cell where LBT failed in the PHY layer or MAC layer before the LBT procedure succeeded;

[0164] - The identifier of the UL BWP in the target cell where the LBT procedure was successful;

[0165] - an identifier of each ULBWP in the target cell for which LBT failed in the PHY layer or the MAC layer before the LBT procedure succeeded;

[0166] - The time period from the last handover execution until a successful LBT procedure with the target cell;

[0167] - The time period from the last handover execution until one of the following events occurs with the target cell: preamble transmission, MSG3 transmission in a 4-step RA procedure, or MSGA transmission in a 2-step RA procedure;

[0168] - the time period that has passed since a successful LBT procedure with the target cell until the handover procedure has been successfully completed; or

[0169] - The time period that elapses from when the handover procedure has been successfully completed until the SHR is reported.

[0170] Solution 3-2

[0171] This solution can be applied to the DAPS handover process. In addition to the above four trigger conditions (i.e., trigger conditions 1 to 4), at least one of the following trigger conditions for SHR of the DAPS handover process in NR-U can be configured:

[0172] Trigger conditions 1 to 4 are the same as the above-mentioned trigger conditions 1 to 4 in solution 3-1, so the details are omitted here.

[0173] Trigger condition 5: When the time period from the last handover execution until the successful LBT process with the source cell (labeled as P6 for clarity) is lower than the threshold (labeled as threshold5 for clarity), SHR is triggered. The threshold (i.e., threshold5) can be configured by the source node, and then; the source node can send the threshold (i.e., threshold5) to the UE via an RRC reconfiguration message.

[0174] When trigger condition 5 is met, the UE may store the following in the SHR, and the UE may report the SHR to the network (e.g., the target node or the third node to which the UE is connected after a successful handover). The SHR may include at least one of the following:

[0175] - SHR cause associated with the triggering condition;

[0176] - The identifier of the UL BWP in the source cell where the LBT procedure was successful;

[0177] - an identifier of each UL BWP in the source cell for which LBT failed in the PHY layer or MAC layer (if any) before the LBT procedure with the source cell succeeded. The identifier may not be present in the case where there is no LBT failure in the PHY layer or MAC layer before the LBT procedure with the source cell succeeded, or in the case where LBT with the source cell succeeded on the first UL BWP;

[0178] - the total number of UL BWPs in the source cell where LBT failed in the PHY layer or MAC layer (if any) before the LBT procedure with the source cell succeeded. Before the LBT procedure with the source cell succeeded, in the case where there was no LBT failure in the PHY layer or MAC layer, or in the case where LBT with the source cell succeeded on the first UL BWP, the total number of UL BWPs may be zero or non-existent;

[0179] - The identifier of the UL BWP in the target cell where the LBT procedure was successful;

[0180] - an identifier for each UL BWP in the target cell for which LBT failed in the PHY layer or the MAC layer (if any) before the LBT procedure with the target cell succeeded. The identifier may not be present in case there is no LBT failure in the PHY layer or the MAC layer before the LBT procedure succeeded, or in case LBT with the target cell succeeded on the UL BWP of the target cell on the first RACH attempt;

[0181] - the total number of UL BWPs in the target cell for which LBT failed in the PHY layer or MAC layer (if any) before the LBT procedure with the target cell succeeded. In the case where there is no LBT failure in the PHY layer or MAC layer before the LBT procedure succeeded, or in the case where LBT with the target cell succeeded on the UL BWP of the target cell on the first RACH attempt, the total number of UL BWPs may be zero or absent;

[0182] - The time period from the last handover execution until a successful LBT procedure with the source cell has elapsed;

[0183] - The time period from the last handover execution until a successful LBT procedure with the target cell;

[0184] - The time period from the last handover execution until one of the following events occurs with the target cell: preamble transmission, MSG3 transmission in a 4-step RA procedure, or MSGA transmission in a 2-step RA procedure;

[0185] - the time period that has passed since a successful LBT procedure with the source cell until the handover procedure has been successfully completed;

[0186] - the time period that has passed since a successful LBT procedure with the target cell until the handover procedure has been successfully completed; or

[0187] - The time period that elapses from when the handover procedure has been successfully completed until the SHR is reported.

[0188] Trigger condition 6: When the ratio (labeled as ratio6 for clarity) is lower than the threshold (labeled as threshold6 for clarity), trigger SHR. The ratio (e.g., ratio6) can be determined based on the following two numbers associated with the UL BWP in the source cell:

[0189] - N3: the total number of UL BWPs in the source cell where persistent LBT failures occurred, e.g. in the MAC layer; and

[0190] - N4: The total number of UL BWPs in the source cell, for example, which are configured with UL resources. That is, the total number of UL BWPs in which the UE can perform a RACH procedure in the source cell, or the total number of UL BWPs configured by the network for a handover procedure, for example, the total number of UL BWPs configured with a RACH configuration for a RACH procedure in the source cell, or the total number of UL BWPs in which the UE can perform uplink data transmission in the source cell.

[0191] The ratio (ratio6) can be calculated by the following formula (5):

[0192]

[0193] In summary, when ratio6 is lower than threshold6, SHR is triggered. The threshold (ie, threshold6) may be configured by the source node. Then, the source node may send threshold6 to the UE via an RRC reconfiguration message.

[0194] When trigger condition 6 is met, the UE may store the following in the SHR, and the UE may report the SHR to the network (e.g., the target node or the third node to which the UE is connected after a successful handover). The SHR may include at least one of the following:

[0195] - SHR cause associated with the triggering condition;

[0196] - an identifier of each UL BWP in the source cell where LBT failed in a lower layer (e.g., PHY layer or MAC layer);

[0197] - The identifier of the UL BWP in the source cell where the LBT procedure was successful;

[0198] - The total number of UL BWPs in the source cell where LBT failed in the PHY layer or MAC layer before the LBT procedure with the source cell succeeded;

[0199] - The identifier of the UL BWP in the target cell where the LBT procedure was successful;

[0200] - an identifier for each UL BWP in the target cell for which LBT failed in the PHY layer or the MAC layer (if any) before the LBT procedure with the target cell succeeded. The identifier may not be present in case there is no LBT failure in the PHY layer or the MAC layer before the LBT procedure succeeded, or in case LBT with the target cell succeeded on the UL BWP of the target cell on the first RACH attempt;

[0201] - the total number of UL BWPs in the target cell for which LBT failed in the PHY layer or MAC layer (if any) before the LBT procedure with the target cell succeeded. In the case where there is no LBT failure in the PHY layer or MAC layer before the LBT procedure succeeded, or in the case where LBT with the target cell succeeded on the UL BWP of the target cell on the first RACH attempt, the total number of UL BWPs may be zero or absent;

[0202] - The time period from the last handover execution until a successful LBT procedure with the source cell has elapsed;

[0203] - The time period from the last handover execution until a successful LBT procedure with the target cell;

[0204] - The time period from the last handover execution until one of the following events occurs with the target cell: preamble transmission, MSG3 transmission in a 4-step RA procedure, or MSGA transmission in a 2-step RA procedure;

[0205] - the time period that has passed since a successful LBT procedure with the source cell until the handover procedure has been successfully completed;

[0206] - the time period that has elapsed from a successful LBT procedure with the target cell until the handover procedure has been successfully completed, or

[0207] - The time period that elapses from when the handover procedure has been successfully completed until the SHR is reported.

[0208] Trigger condition 7: RLF occurs at the source cell during the DAPS handover process while timer T304 is running, and the RLF is not caused by LBT failure, which may include persistent LBT failure in the RRC layer or the MAC layer.

[0209] When trigger condition 7 is met, the UE may store the following in the SHR, and the UE may report the SHR to the network (e.g., the target node or the third node to which the UE is connected after a successful handover). The SHR may include at least one of the following:

[0210] - SHR cause associated with the triggering condition;

[0211] - an indication indicating that the cause of the RLF in the source cell is not due to LBT failure while the timer T304 is running;

[0212] - an identifier of each UL BWP in the source cell where LBT failed in a lower layer (if any) (e.g., PHY layer or MAC layer). The identifier may not be present before the LBT procedure with the source cell succeeds, in the case where there is no LBT failure in the PHY layer or MAC layer, or in the case where LBT with the source cell succeeds on the first UL BWP;

[0213] -The total number of UL BWPs in the source cell where LBT failed in the PHY layer or MAC layer (if any). Before the LBT procedure with the source cell succeeds, in the case where there is no LBT failure in the PHY layer or MAC layer, or in the case where LBT with the source cell succeeds on the first UL BWP, the total number of UL BWPs may be zero or non-existent;

[0214] - The identifier of the UL BWP in the target cell where the LBT procedure was successful;

[0215] - an identifier for each UL BWP in the target cell for which LBT failed in the PHY layer or the MAC layer (if any) before the LBT procedure with the target cell succeeded. The identifier may not be present in case there is no LBT failure in the PHY layer or the MAC layer before the LBT procedure succeeded, or in case LBT with the target cell succeeded on the UL BWP of the target cell on the first RACH attempt;

[0216] - the total number of UL BWPs in the target cell for which LBT failed in the PHY layer or MAC layer (if any) before the LBT procedure with the target cell succeeded. In the case where there is no LBT failure in the PHY layer or MAC layer before the LBT procedure succeeded, or in the case where LBT with the target cell succeeded on the UL BWP of the target cell on the first RACH attempt, the total number of UL BWPs may be zero or absent;

[0217] - the time period from the last handover execution until the RLF in the source cell elapses;

[0218] - The time period from the last handover execution until a successful LBT procedure with the target cell;

[0219] - The time period from the last handover execution until one of the following events occurs with the target cell: preamble transmission, MSG3 transmission in a 4-step RA procedure, or MSGA transmission in a 2-step RA procedure;

[0220] - the time period that has elapsed from a successful LBT procedure with the target cell until the handover procedure has been successfully completed, or

[0221] - The time period that elapses from when the handover procedure has been successfully completed until the SHR is reported.

[0222] The UE may store the above information related to the successful handover in the SHR until the SHR is retrieved by the network, or store the information related to the successful handover for 48 hours. In some embodiments, the UE may successfully access the target cell and remain in the target cell. In some other embodiments, the UE may have successfully accessed the target cell, however, within a short period of time, if RLF occurs in the target cell, the UE performs an RRC reestablishment procedure and accesses a third cell. In some other embodiments, the UE may have successfully accessed the target cell, however, within a short period of time, the UE performs another handover procedure and accesses a third cell.

[0223] After switching to the target cell or accessing the third cell, the UE may transmit an indication to the target node or the third node indicating that the successful handover related information in the successful handover report is available at the UE. For example, the availability of the successful handover report may be indicated by a handover completion message (ie, RRCReconfigurationComplete), an RRC reconstruction completion message, an RRC establishment completion message, or an RRC recovery completion message. The target node or the third node may extract the information of the successful handover report via a UE information request / response mechanism. That is, the target node or the third node may transmit a request (e.g., a UE information request message) for the successful handover related information contained in the successful handover report. After receiving the request, the UE may transmit a successful handover report containing the successful handover related information to the target node or the third node via a UE information response message.

[0224] At the third node side, it can transmit the SHR from the UE to the target node (for example, when the SHR is triggered due to the satisfaction of the triggering condition related to timer T304), to the source node (for example, when the SHR is triggered due to the satisfaction of the triggering condition related to timer T310 or timer T312), or both.

[0225] At the target node side, it may receive an SHR from the UE or from a third node. The target node may detect or analyze radio link problems during the handover process based on the received SHR. Based on the SHR, the target node may update mobility-related configurations, such as updating the RACH configuration toward the target cell. Alternatively, the target node may modify a configuration associated with LBT, such as a configuration for LBT failure recovery. For example, the target node may modify a timer (i.e., lbt-FailureDetectionTimer) for continuous uplink LBT failure detection, and the target node may modify a count number (i.e., lbt-FailureInstanceMaxCount) that determines how many continuous uplink LBT failure events the UE triggers for uplink LBT failure recovery. The target node may also transmit an SHR to the source node.

[0226] At the source node side, the source node may receive SHR or successful handover related information from the target node or from a third node. The source node may modify LBT related configurations, such as received signal strength indicator (RSSI) or channel occupancy (CO) measurement configurations. The source node may update the configuration for LBT failure recovery, such as a timer for continuous uplink LBT failure detection (i.e., lbt-FailureDetectionTimer), and a count number (i.e., lbt-FailureInstanceMaxCount) for determining how many continuous uplink LBT failure events the UE triggers for uplink LBT failure recovery. The source node may update mobility related parameters based on the received SHR, such as modifying the RSRP threshold, RSRQ threshold, or SINR threshold used for the handover process.

[0227] Figure 3 A method performed by a UE for enhancing SHR according to some embodiments of the present disclosure is described.

[0228] In operation 301, the UE may receive a configuration associated with a handover procedure in an unlicensed spectrum, wherein the configuration indicates one or more trigger conditions associated with a successful handover report of a successfully completed handover procedure. In operation 302, in response to at least one of the one or more trigger conditions being satisfied, the successful handover related information is stored in the successful handover report.

[0229] In some embodiments, the one or more trigger conditions include at least one of the following:

[0230] - A ratio between a first time period from the last handover execution until a successful LBT process with the target cell and a configured value of timer T304 is lower than a first threshold. For example, the ratio may include ratio1 in trigger condition 1 as described in solution 3-1.

[0231] - A ratio between the value of the elapsed time of one of timer T304, timer T310 or timer T312 and the configured value of one of timer T304, timer T310 or timer T312 is higher than a second threshold. For example, the ratio may include ratio2 in trigger condition 2 as described in solution 3-1.

[0232] - The ratio between the first time period and the value of the elapsed time of the timer T304 is lower than a third threshold. For example, the ratio may include ratio3 in trigger condition 3 as described in solution 3-1.

[0233] - A ratio between the total number of UL BWPs in the target cell where persistent LBT failure occurs and the total number of UL BWPs associated with RA procedures in the target cell is lower than a fourth threshold. For example, the ratio may include ratio4 in trigger condition 4 as described in solution 3-1.

[0234] - A second time period from the last handover execution until a successful LBT process with the source cell is below a fifth threshold, such as the time period in trigger condition 5 described in solution 3-2.

[0235] - A ratio between the total number of UL BWPs in the source cell where persistent LBT failures occur and the total number of UL BWPs of the source cell is lower than a sixth threshold. For example, the ratio may include ratio6 in trigger condition 6 as described in solution 3-2.

[0236] - RLF in the source cell is not due to LBT failure, where the RLF occurs at the source cell during the DAPS handover procedure while the timer T304 is running. For example, trigger condition 7 as described in solution 3-2.

[0237] In some embodiments, the successful handover related information includes at least one of the following:

[0238] - The identifier of the UL BWP in the source cell where the LBT procedure was successful;

[0239] - an identifier of the UL BWP in the source cell where LBT failed in the PHY layer or MAC layer before the LBT procedure succeeded;

[0240] - The total number of UL BWPs in the source cell where LBT failed in the PHY layer or MAC layer before the LBT procedure succeeded;

[0241] - The identifier of the UL BWP in the target cell where the LBT procedure was successful;

[0242] - an identifier of the UL BWP in the target cell where LBT failed in the PHY layer or MAC layer before the LBT procedure succeeded;

[0243] -The total number of UL BWPs in the target cell where LBT failed in the PHY layer or MAC layer before the LBT procedure succeeded;

[0244] - The time period from the last handover execution until a successful LBT procedure with the target cell;

[0245] - The time period from the last handover execution until a successful LBT procedure with the source cell has elapsed;

[0246] - the time period from the last handover execution until UL data transmission with the source cell;

[0247] - the time period that elapsed from the last handover execution until the preamble transmission;

[0248] - the time period that has passed since the last handover was performed until MSG3 was transmitted;

[0249] - the time period that elapsed from the last switch execution until the MSGA launch;

[0250] - the time period that has passed since the successful LBT procedure with the target cell until the handover procedure has been successfully completed;

[0251] - the time period that has elapsed from a successful LBT procedure with the source cell until the handover procedure has been successfully completed; or

[0252] - An indication indicating that the RLF in the source cell is not due to LBT failure, wherein the RLF occurs at the source cell during the DAPS handover procedure while the timer T304 is running.

[0253] In some embodiments, in the case where the first non-repetitive packet from the target cell during the DAPS handover process is received earlier than the last packet from the source cell during the DAPS handover process, the successful handover related information includes an interruption time having a zero value, or the successful handover related information does not include the interruption time. That is, the SHR may include an interruption time having a zero value, or may not include an interruption time.

[0254] In some embodiments, for example, in embodiments where the first non-duplicate packet from the target cell during the DAPS handover process is received earlier than, later than, or simultaneously with the last packet from the source cell during the DAPS handover process, the interruption time includes at least one of:

[0255] - The interruption time of each DAPS bearer;

[0256] - The outage time of each non-DAPS bearer;

[0257] - the interruption time from the last PDCP PDU received from the DAPS bearer or non-DAPS bearer of the source cell until the first non-duplicate PDCP PDU received from the DAPS bearer or non-DAPS bearer of the target cell;

[0258] -The maximum outage time among all DAPS bearer outage times;

[0259] -The maximum outage time among all non-DAPS bearer outage times;

[0260] - The maximum outage time among all DAPS bearer and non-DAPS bearer outage times;

[0261] -The minimum interruption time among all DAPS bearer interruption times;

[0262] -The minimum outage time among all non-DAPS bearer outage times;

[0263] -The minimum interruption time among all DAPS bearer and non-DAPS bearer interruption times;

[0264] - The average outage duration among all DAPS bearer outage durations;

[0265] - the average outage duration among all non-DAPS bearer outage durations; or

[0266] - The average outage time among all DAPS bearer and non-DAPS bearer outage times.

[0267] In some embodiments, the outage time is measured based on one of:

[0268] - The interruption time is measured from the last PDCP PDU received from the DAPS bearer or non-DAPS bearer of the source cell until the first non-duplicate PDCP PDU received from the DAPS bearer or non-DAPS bearer of the target cell;

[0269] - the interruption time is measured per DAPS bearer, where for each DAPS bearer the interruption time is measured from the last PDCP PDU received from the source cell of the DAPS bearer until the first non-duplicate PDCP PDU received from the target cell of the DAPS bearer; or

[0270] - The interruption time is measured per bearer including all DAPS bearers and all non-DAPS bearers. For each bearer, the interruption time is measured from the last PDCP PDU received by the self-bearing source cell until the first non-duplicate PDCP PDU received by the self-bearing target cell.

[0271] In some embodiments, the processor is further configured to perform at least one of: transmitting an indication for storing successful handover related information in a successful handover report; receiving a request for successful handover related information in the successful handover report; or transmitting a successful handover report.

[0272] Figure 4 A method performed by a RAN node for enhancing SHR according to some embodiments of the present disclosure is described.

[0273] In operation 401, the RAN node may generate a configuration associated with a handover procedure in an unlicensed spectrum, wherein the configuration indicates one or more trigger conditions associated with a successful handover report of a handover procedure that has been successfully completed. In operation 402, the RAN node may transmit the configuration associated with the handover procedure.

[0274] In some embodiments, the RAN node is a target node (e.g., Figure 1 In the case of BS102-B in FIG. 1 , and one or more triggering conditions include at least one of the following:

[0275] - a ratio between a first time period from the last handover execution until a successful LBT procedure with the target cell and a configured value of the timer T304 is lower than a first threshold;

[0276] - the ratio between the value of the elapsed time of the timer T304 and the configured value of the timer T304 is higher than a second threshold;

[0277] - the ratio between the first time period and the value of the elapsed time of the timer T304 is lower than a third threshold; or

[0278] - A ratio between the total number of UL BWPs in the target cell in which persistent LBT failures occur and the total number of UL BWPs associated with RA procedures in the target cell is below a fourth threshold.

[0279] The above trigger conditions may be generated by the target node and transmitted to the source node.

[0280] In some embodiments, the RAN node may be a target node, and the processor is further configured to: transmit a configuration associated with the handover process to the source node. For example, the RAN node may transmit a trigger condition associated with the timer T304 to the source node.

[0281] In some embodiments, the RAN node may be a target node, and the processor is further configured to perform at least one of: receiving a successful handover report from the UE or a third RAN node; or modifying a configuration associated with the LBT based on the successful handover report.

[0282] In some embodiments, the RAN node may be a source node (e.g., Figure 1 BS102-A in the RAN node), and the processor is further configured to: transmit a configuration associated with the handover process to the UE. For example, the RAN node may transmit a trigger condition associated with the timer T310 or T312 to the UE.

[0283] In some embodiments, the RAN node may be a source node, and the processor is further configured to perform at least one of: receiving a successful switching report from a target RAN node or a third RAN node; or modifying a configuration associated with the LBT based on the successful switching report.

[0284] In some embodiments, the RAN node may be a source node, and the one or more triggering conditions include at least one of the following:

[0285] - a ratio between a value of the elapsed time of one of the timers T310 or T312 and a configured value of one of the timers T310 or T312 is higher than a fifth threshold;

[0286] - a second time period from the last handover execution until a successful LBT procedure with the source cell is below a sixth threshold;

[0287] - wherein the ratio between the total number of UL BWPs in the source cell where persistent LBT failures occur and the total number of UL BWPs of the source cell is below a seventh threshold; or

[0288] - The RLF in the source cell is not due to LBT failure, where the RLF occurs at the source cell during the DAPS handover procedure while the timer T304 is running.

[0289] In some embodiments, in a case where the interruption time in the successful handover related information has a zero value or does not include the interruption time in the successful handover related information, the RAN node may maintain the current mobility configuration associated with the DAPS handover procedure.

[0290] Figure 5 A simplified block diagram illustrating an exemplary apparatus according to some embodiments of the present disclosure.

[0291] like Figure 5, an example of apparatus 500 may include at least one processor 504 and at least one transceiver 502 coupled to the processor 504. Apparatus 500 may be a UE, a BS, a RAN node, a source node, a target node, a third node, or any other device having similar functionality.

[0292] Although in this figure, elements such as at least one transceiver 502 and processor 504 are described in the singular, the plural is contemplated unless limitation to the singular is explicitly stated. In some embodiments of the present disclosure, the transceiver 502 may be divided into two devices, such as a receiving circuit system and a transmitting circuit system. In some embodiments of the present disclosure, the device 500 may further include an input device, a memory, and / or other components.

[0293] In some embodiments of the present disclosure, the device 500 may be a UE. The transceiver 502 and the processor 504 may interact with each other to perform Figures 1 to 4 In some embodiments of the present disclosure, the device 500 may be a node. The transceiver 502 and the processor 504 may interact with each other to perform Figures 1 to 4 The operation of a node described in any of .

[0294] In some embodiments of the present disclosure, the apparatus 500 may further include at least one non-transitory computer-readable medium.

[0295] For example, in some embodiments of the present disclosure, the non-transitory computer-readable medium may have computer-executable instructions stored thereon to cause the processor 504 to implement the method for the UE as described above. For example, when executed, the computer-executable instructions cause the processor 504 to interact with the transceiver 502 to perform Figures 1 to 4 Operation of the UE described in any one of .

[0296] In some embodiments of the present disclosure, the non-transitory computer-readable medium may have computer-executable instructions stored thereon to cause the processor 504 to implement the method for the node as described above. For example, when executed, the computer-executable instructions cause the processor 504 to interact with the transceiver 502 to perform Figures 1 to 4 The operation of a node described in any of .

[0297] The method of the present disclosure can be implemented on a programmed processor. However, the controller, flow chart and module can also be implemented on a general or special purpose computer, a programmed microprocessor or microcontroller and peripheral integrated circuit components, an integrated circuit, a hardware electronic or logic circuit (such as a discrete element circuit), a programmable logic device, etc. In general, any device with a finite state machine capable of implementing the flow chart shown in the figure can be used to implement the processing functions of the present disclosure.

[0298] Although the present disclosure has been described with its specific embodiments, it is apparent that many alternatives, modifications and variations will be apparent to those skilled in the art. For example, the various components of the embodiments may be interchanged, added or replaced in other embodiments. In addition, all elements shown in each figure are not necessarily required for the operation of the disclosed embodiments. For example, a person of ordinary skill in the art of the disclosed embodiments will be able to make and use the teachings of the present disclosure by simply adopting the elements of the independent claims. Therefore, the embodiments of the present disclosure as described herein are intended to be illustrative, not restrictive. Various changes may be made without departing from the spirit and scope of the present disclosure.

[0299] In the present disclosure, relational terms such as "first", "second", etc. can be used only to distinguish one entity or action from another entity or action, without necessarily requiring or implying any actual such relationship or order between such entities or actions. The term "comprises / comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also may include other elements that are not explicitly listed or inherent to such processes, methods, articles or equipment. In the absence of more constraints, elements starting with "a / an" or the like do not exclude the presence of additional identical elements in the process, method, article or equipment including the elements. In addition, the term "another" is defined as at least a second or more. The terms "include", "have" and the like as used herein are defined as "include".

Claims

1. A user equipment UE, comprising: Transceiver; and a processor coupled to the transceiver and configured to: receiving a configuration associated with a handover procedure in an unlicensed spectrum, wherein the configuration indicates one or more trigger conditions associated with a successful handover report of the handover procedure having been successfully completed; and In response to at least one of the one or more trigger conditions being satisfied, successful handover related information is stored in the successful handover report.

2. The UE according to claim 1, wherein the one or more trigger conditions include at least one of the following: a ratio between a first time period from the last handover execution until a successful LBT procedure with the target cell and a configured value of the timer T304 is lower than a first threshold; a ratio between a value of an elapsed time of one of the timer T304, the timer T310, or the timer T312 and the configured value of the one of the timer T304, the timer T310, or the timer T312 is higher than a second threshold; the ratio between the first time period and the value of the elapsed time of the timer T304 is lower than a third threshold; wherein a ratio between a total number of uplink UL bandwidth parts BWPs in the target cell where persistent LBT failures occur and a total number of UL BWPs associated with a random access RA procedure in the target cell is lower than a fourth threshold; a second time period from the last handover execution until a successful LBT process with the source cell is below a fifth threshold; wherein a ratio between the total number of UL BWPs in the source cell where persistent LBT failures occur and the total number of ULBWPs of the source cell is lower than a sixth threshold; or The radio link failure RLF in the source cell is not caused by LBT failure, wherein the RLF occurs at the source cell during a dual active protocol stack DAPS handover procedure while a timer T304 is running.

3. The UE according to claim 1, wherein the successful handover related information comprises at least one of the following: The identifier of the UL BWP in the source cell where the LBT procedure was successful; wherein the identifier of the UL BWP in the source cell where the LBT failed in the physical PHY layer or the media access control MAC layer before the LBT process succeeded; wherein the total number of UL BWPs in the source cell for which LBT failed in the PHY layer or the MAC layer before the LBT process succeeded; The identifier of the UL BWP in the target cell where the LBT procedure is successful; wherein an identifier of a UL BWP in the target cell for which LBT failed in the PHY layer or the MAC layer before the LBT process succeeded; wherein the total number of UL BWPs in the target cell for which LBT failed in the PHY layer or the MAC layer before the LBT process succeeded; the time period from the last handover execution until a successful LBT process with the target cell; a time period from the last handover execution until a successful LBT process with the source cell; a time period from the last handover execution until UL data transmission with the source cell; a time period that elapses from the last handover execution until the preamble transmission; the time period that elapses from the last handover execution until the MSG3 transmission; the time period that elapsed from the last switching execution until the MSGA launch; a time period elapsed from the successful LBT procedure with the target cell until the handover procedure has been successfully completed; a time period elapsed from the successful LBT procedure with the source cell until the handover procedure has been successfully completed; or An indication indicating that the RLF in the source cell is not due to LBT failure, wherein the RLF occurs at the source cell during a DAPS handover procedure while the timer T304 is running.

4. The UE according to claim 1, wherein in a case where a first non-repetitive packet from a target cell during a DAPS handover procedure is received earlier than a last packet from a source cell during the DAPS handover procedure, the successful handover related information includes an interruption time having a zero value, or the successful handover related information does not include the interruption time.

5. The UE according to claim 1 or claim 4, wherein the interruption time includes at least one of the following: The interruption time of each DAPS bearer; The outage time of each non-DAPS bearer; an interruption time elapsed from the last packet data convergence protocol PDCP protocol data unit PDU received from the DAPS bearer or non-DAPS bearer of the source cell until the first non-duplicate PDCP PDU received from the DAPS bearer or non-DAPS bearer of the target cell; The maximum outage time among all DAPS bearer outage times; The maximum outage duration among all non-DAPS bearer outage durations; The maximum outage duration among all DAPS bearer and non-DAPS bearer outage durations; The minimum interruption time among all DAPS bearer interruption times; The minimum outage time among all non-DAPS bearer outage times; The minimum interruption time among all interruption times of DAPS bearers and non-DAPS bearers; The average outage duration among all DAPS-borne outage durations; The average outage duration among all non-DAPS bearer outage durations; or The average outage duration among all DAPS bearer and non-DAPS bearer outage durations.

6. The UE of claim 4, wherein the outage time is measured based on one of: The interruption time is measured from the last PDCP PDU received from the DAPS bearer or non-DAPS bearer of the source cell until the first non-duplicate PDCP PDU received from the DAPS bearer or non-DAPS bearer of the target cell; The interruption time is measured per DAPS bearer, and for each DAPS bearer, the interruption time is measured from the last PDCP PDU received from the source cell of the DAPS bearer until the first non-repeated PDCP PDU received from the target cell of the DAPS bearer; or The interruption time is measured for each bearer including all DAPS bearers and all non-DAPS bearers, and for each bearer, the interruption time is measured from the last PDCP PDU received from the source cell of the bearer until the first non-repeated PDCP PDU received from the target cell of the bearer.

7. A radio access network RAN ​​node, comprising: Transceiver; and a processor coupled to the transceiver and configured to: generating a configuration associated with a handover procedure in an unlicensed spectrum, wherein the configuration indicates one or more trigger conditions associated with a successful handover report of the handover procedure having been successfully completed; and The configuration associated with the handover process is transmitted.

8. The RAN node according to claim 7, wherein in the case where the RAN node is a target node, and the one or more trigger conditions include at least one of the following: a ratio between a first time period from the last handover execution until a successful LBT procedure with the target cell and a configured value of the timer T304 is lower than a first threshold; a ratio between the value of the elapsed time of the timer T304 and the configured value of the timer T304 is higher than a second threshold; The ratio between the first period of time and the value of the elapsed time of the timer T304 is lower than a third threshold value; or A ratio between a total number of uplink UL bandwidth parts BWPs in the target cell in which persistent LBT failures occur and a total number of UL BWPs associated with a random access RA procedure in the target cell is lower than a fourth threshold.

9. The RAN node of claim 7, wherein if the RAN node is a target node, the processor is further configured to perform at least one of the following: receiving a successful handover report from a user equipment UE or a third RAN node; or A configuration associated with the LBT is modified based on the successful switching report.

10. The RAN node of claim 7, wherein in case the RAN node is a source node, the processor is further configured to perform at least one of the following: receiving a successful handover report from the target RAN node or a third RAN node; or A configuration associated with the LBT is modified based on the successful switching report.

11. The RAN node according to claim 7, wherein in the case where the RAN node is a source node, and the one or more trigger conditions include at least one of the following: a ratio between a value of an elapsed time of one of the timer T310 or the timer T312 and a configured value of the one of the timer T310 or the timer T312 is higher than a fifth threshold; a second time period from the last handover execution until a successful LBT process with the source cell is below a sixth threshold; wherein a ratio between the total number of UL BWPs in the source cell where persistent LBT failures occur and the total number of ULBWPs of the source cell is lower than a seventh threshold; or The radio link failure RLF in the source cell is not caused by LBT failure, wherein the RLF occurs at the source cell during a dual active protocol stack DAPS handover procedure while a timer T304 is running.

12. The RAN node according to claim 7, wherein the successful handover related information comprises at least one of the following: The identifier of the UL BWP in the source cell where the LBT procedure was successful; wherein the identifier of the UL BWP in the source cell where the LBT failed in the physical PHY layer or the media access control MAC layer before the LBT process succeeded; wherein the total number of UL BWPs in the source cell for which LBT failed in the PHY layer or the MAC layer before the LBT process succeeded; The identifier of the UL BWP in the target cell where the LBT procedure is successful; wherein an identifier of a UL BWP in the target cell for which LBT failed in the PHY layer or the MAC layer before the LBT process succeeded; wherein the total number of UL BWPs in the target cell for which LBT failed in the PHY layer or the MAC layer before the LBT process succeeded; the time period from the last handover execution until a successful LBT process with the target cell; a time period from the last handover execution until a successful LBT process with the source cell; a time period from the last handover execution until UL data transmission with the source cell; a time period that elapses from the last handover execution until the preamble transmission; the time period that elapses from the last handover execution until the MSG3 transmission; the time period that elapsed from the last switching execution until the MSGA launch; a time period elapsed from the successful LBT procedure with the target cell until the handover procedure has been successfully completed; a time period elapsed from the successful LBT procedure with the source cell until the handover procedure has been successfully completed; or An indication indicating that the RLF in the source cell is not due to LBT failure, wherein the RLF occurs at the source cell during a DAPS handover procedure while the timer T304 is running.

13. The RAN node according to claim 7, wherein in a case where a first non-duplicate packet from a target cell during a DAPS handover procedure is received earlier than a last packet from a source cell during the DAPS handover procedure, the successful handover related information includes an interruption time having a zero value, or the successful handover related information does not include the interruption time.

14. The RAN node according to claim 7 or claim 13, wherein the interruption time comprises at least one of the following: The interruption time of each DAPS bearer; The outage time of each non-DAPS bearer; an interruption time elapsed from the last packet data convergence protocol PDCP protocol data unit PDU received from the DAPS bearer or non-DAPS bearer of the source cell until the first non-duplicate PDCP PDU received from the DAPS bearer or non-DAPS bearer of the target cell; The maximum outage time among all DAPS bearer outage times; The maximum outage duration among all non-DAPS bearer outage durations; The maximum outage duration among all DAPS bearer and non-DAPS bearer outage durations; The minimum interruption time among all DAPS bearer interruption times; The minimum outage time among all non-DAPS bearer outage times; The minimum interruption time among all interruption times of DAPS bearers and non-DAPS bearers; The average outage duration among all DAPS-borne outage durations; The average outage duration among all non-DAPS bearer outage durations; or The average outage duration among all DAPS bearer and non-DAPS bearer outage durations.

15. A method performed by a user equipment UE, comprising: receiving a configuration associated with a handover procedure in an unlicensed spectrum, wherein the configuration indicates one or more trigger conditions associated with a handover report of the handover procedure being successfully completed; and In response to at least one of the one or more trigger conditions being satisfied, successful handover related information is stored in a successful handover report.

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