Terminal and communication method

Abstract

This terminal executes handover in accordance with mobility control performed by a lower layer. The terminal transmits, to a network, a report relating to the handover. The report includes information that indicates conditions when the handover fails.

Description

Terminal and Communication Method

[0001] The present disclosure relates to a terminal that supports L1 / L2 mobility (LTM) and a communication method.

[0002] The 3rd Generation Partnership Project (3GPP: registered trademark) is standardizing the 5th generation mobile communication system (also called 5G, New Radio (NR) or Next Generation (NG)), and is also promoting the standardization of the next generation, called Beyond 5G, 5G Evolution or 6G.

[0003] For example, in 3GPP Release 18, the extension of layer 1 / layer 2 mobility (L1 / L2 mobility) is being discussed. L1 / L2 mobility, also called Lower layer Triggered Mobility (LTM), is a technology related to the mobility of a terminal (User Equipment, UE) in layer 1 or layer 2, and includes the transition (handover (HO)) of the UE to other cells, etc. The HO by LTM is realized by a lower layer such as the Media Access Control layer (MAC).

[0004] In LTM, the base station of the handover source can pre-set the information of the handover candidate cell to the UE based on the conventional L3 quality measurement report. Before the handover is executed, the base station of the handover source selects the optimal target cell and beam from the handover candidate cells based on the L1 quality measurement report from the UE, and sends a handover instruction to the UE by L2 signaling called a cell switch command.

[0005] Also, in 3GPP Release 19, the extension of SON (Self-Organizing Networks) related to LTM is being studied (Non-Patent Document 1).

[0006] "New WID: Data collection for SON (Self-Organising Networks) / MDT (Minimization of Drive Tests) in NR standalone and MR-DC (Multi-Radio Dual Connectivity) Phase 4", RP-234038, 3GPP TSG RAN Meeting #102, 3GPP, December 2023

[0007] In LTM, the UE may monitor its state according to specific execution conditions, such as in Conditional Handover (CHO), and execute the LTM if the execution conditions are met (hereinafter referred to as Conditional LTM).

[0008] However, when applying Conditional LTM, it is unclear what should be reported to the network in the event of a Conditional LTM failure. As a result, the network faces the challenge of not being able to identify the cause of a Conditional LTM handover (HO) failure.

[0009] Therefore, the following disclosure is made in light of these circumstances and aims to provide terminals and communication methods that can contribute to the realization of SON related to LTM, even when Conditional LTM is applied.

[0010] One aspect of the present disclosure comprises a control unit (control unit 240) that performs a handover in accordance with mobility control by a lower layer, and a transmission unit (RLF / HO reporting unit 220) that transmits a report on the handover to a network, wherein the transmission unit is a terminal (UE 200) that transmits the report, which includes information indicating the situation in the event of a handover failure.

[0011] One aspect of this disclosure is a communication method for a terminal (UE200) that includes the steps of performing a handover in accordance with mobility control by a lower layer, and transmitting a report relating to the handover to a network, which includes information indicating the circumstances in the event of a handover failure.

[0012] Figure 1 is an overall schematic diagram of the wireless communication system 10. Figure 2 is a diagram showing an example of control by L1 / L2 mobility. Figure 3 is a functional block diagram of gNB100. Figure 4 is a functional block diagram of UE200. Figure 5 is a diagram showing an example of the measurement procedure for UE measured TA. Figure 6 is a diagram showing an example of the sequence for RLF report / handover failure report. Figure 7 is a diagram showing an example of the sequence for successful handover report. Figure 8 is a diagram showing an example of the hardware configuration of gNB100 and UE200. Figure 9 is a diagram showing an example of the configuration of vehicle 2001.

[0013] The embodiments will be described below with reference to the drawings. Note that identical or similar reference numerals are used to denote the same functions and components, and their descriptions will be omitted as appropriate.

[0014] (1) Overall schematic diagram 1 of the wireless communication system is an overall schematic diagram of the wireless communication system 10 according to this embodiment. The wireless communication system 10 is a wireless communication system in accordance with 5G New Radio (NR) and includes a Next Generation-Radio Access Network 20 (hereinafter referred to as NG-RAN20) and a terminal 200 (User Equipment 200, hereinafter referred to as UE200).

[0015] The wireless communication system 10 may be a wireless communication system conforming to a method called Beyond 5G, 5G Evolution, or 6G, or it may include a wireless communication system conforming to a method called Long Term Evolution (LTE) or 4G. The wireless communication system 10 may support functions related to the Industrial Internet of Things (IIoT) and URLLC (Ultra-Reliable and Low Latency Communications).

[0016] NG-RAN20 includes a wireless base station 100 (hereinafter referred to as gNB100). The specific configuration of the wireless communication system 10, including the number of gNBs (or eNBs, etc.) and UEs, is not limited to the example shown in Figure 1.

[0017] Furthermore, the gNB100 may employ a fronthaul (FH) interface as defined by the O-RAN (Open Radio Access Network Alliance). The gNB100 may include an O-DU (O-RAN Distributed Unit) and an O-RU (O-RAN Radio Unit). The gNB100 can function as a type of NG-RAN node.

[0018] NG-RAN20 actually includes multiple NG-RAN Nodes, specifically gNBs (or ng-eNBs), and is connected to a 5G-compliant core network (5GC, not shown). NG-RAN20 and 5GC may also be simply referred to as the "network." In 5GC, the concept of CUPS (Control and User Plane Separation) may be introduced, clearly separating the functions of the user plane and the control plane.

[0019] The gNB100 is a radio base station compliant with NR and performs NR-compliant wireless communication with the UE200. The gNB100 may also consist of a CU (Central Unit) and a DU (Distributed Unit), and the DU may be located separately from the CU at a geographically different location. One or more DUs may be connected to the CU. The gNB100 (gNB-CU) may be connected by an Xn interface, and the CU and DU may be connected by an F1 interface (F1-AP, etc.). In this embodiment, the CU may be called a communication device or a central device, etc. The DU may be called a distributed device, etc.

[0020] The gNB100 and UE200 can support Massive MIMO, which generates a more directional beam by controlling the radio signals transmitted from multiple antenna elements; carrier aggregation (CA), which uses multiple component carriers (CCs) bundled together; and dual connectivity (DC), which enables simultaneous communication between the UE and multiple NG-RAN Nodes.

[0021] The DC type may be Multi-RAT Dual Connectivity (MR-DC), which utilizes multiple radio access technologies, or NR-NR Dual Connectivity (NR-DC), which utilizes only NR. For example, one gNB may constitute the master node (MN), and one or more other gNBs may constitute secondary nodes (SN).

[0022] In the wireless communication system 10, not only Layer 3 mobility control of the UE200 (which may also be called L3 Mobility) but also Layer 1 and / or Layer 2 mobility control (L1 / L2 Mobility) may be applied. L1 / L2 Mobility may also be called LTM, and the name LTM will be used primarily below.

[0023] L3 Mobility may be interpreted as mobility control at the Radio Resource Control Layer (RRC). On the other hand, L1 / L2 Mobility may be interpreted as mobility control at the Physical Layer (PHY), Medium Access Control Layer (MAC), Radio Link Control Layer (RLC), and Packet Data Convergence Protocol Layer (PDCP) (mobility control by lower layers).

[0024] Furthermore, in UE-led LTM (UE-based LTM), such as in Conditional Handover (CHO), the UE may perform LTM after the ground network base station (gNB) receives a specific execution condition, monitor its status according to that execution condition, and satisfy the execution condition.

[0025] LTM may also include LTM fast failure recovery. LTM fast failure recovery is a mechanism in which, in the event of an LTM failure, the UE200 performs cell selection, and if the selected cell is an LTM candidate cell, it applies the settings of that candidate cell directly without sending an RRCReestablishmentRequest to the gNB100.

[0026] In the wireless communication system 10, a handover (HO) without a random access procedure may be applied in the LTM. Specifically, UE200 can perform a RACH-less HO, which is an HO that does not use a random access channel (RACH). A RACH-less HO may also be called a RACH-less LTM, etc.

[0027] In RACH-less HO, the UE200 can calculate a Timing Advance (TA) by utilizing the time difference in the reception timing of the signal being measured (e.g., SSB (SS (Synchronization Signal) / PBCH (Physical Broadcast Channel) Block)) between the source cell (which may also be interpreted as the serving cell) of the transition source (handover source) and the target cell of the transition destination (handover destination). Such a TA may be called a UE-measured TA.

[0028] Furthermore, in the case of RACH-less HO, an uplink grant (UL Grant) may be pre-configured that allows the UE200 to send an RRC message (RRC Reconfiguration Complete) after HO completion. Such UL Grants, which also apply to RACH-less HO, may be considered invalid if certain conditions are met.

[0029] In a broad sense, the mobility of the UE200 may refer to the ease of movement and maneuverability of the UE200, but in this embodiment, it may also refer to the minimization of call drop, radio link (including beam) failure, unnecessary handovers, ping-pong situations, etc.

[0030] Figure 2 shows an example of control using L1 / L2 mobility. As shown in Figure 2, the MAC included in the lower layers (Layer 1 / Layer 2), rather than the RRC included in Layer 3, can perform measurement reporting, handover (HO) determination from source cell to target cell (which may include candidate cells), and timer management to determine the success or failure of the HO.

[0031] MAC may report measurement reports and information regarding HO determination to the higher layer (RRC). Based on these reports, RRC may manage the status of wireless resources associated with UE200 cell transitions.

[0032] In this embodiment, the channel includes a control channel and a data channel. The control channel includes PDCCH (Physical Downlink Control Channel), PUCCH (Physical Uplink Control Channel), PRACH (Physical Random Access Channel), and PBCH (Physical Broadcast Channel), among others.

[0033] Furthermore, data channels include PDSCH (Physical Downlink Shared Channel) and PUSCH (Physical Uplink Shared Channel), among others.

[0034] Reference signals include Demodulation Reference Signal (DMRS), Sounding Reference Signal (SRS), Phase Tracking Reference Signal (PTRS), and Channel State Information-Reference Signal (CSI-RS), while signals include channels and reference signals. Furthermore, "data" may refer to data transmitted via a data channel.

[0035] (2) Functional Block Configuration of the Wireless Communication System Next, the functional block configuration of the wireless communication system 10 will be described. Specifically, the functional block configurations of gNB100 and UE200 will be described. Figure 3 is a functional block configuration diagram of gNB100. Figure 4 is a functional block configuration diagram of UE200.

[0036] (2.1) gNB100 As shown in Figure 3, the gNB100 comprises a wireless communication unit 110, a handover processing unit 120, a measurement setting unit 130, and a control unit 140.

[0037] The wireless communication unit 110 transmits a downlink signal (DL signal) in accordance with NR. The wireless communication unit 110 also receives an uplink signal (UL signal) in accordance with NR.

[0038] The TCI state can provide information about antenna ports located in substantially the same location (quasi-collocated: QCL) as the PDCCH antenna ports. If the UE200 has a specific CORESET (control resource sets) spatially located in the same location as a particular CSI-RS, the UE200 can determine which beam is appropriate when attempting to receive the PDCCH using that CORESET. Note that QCL / TCI state / beam may be interpreted as mutually exclusive.

[0039] The handover processing unit 120 performs the handover of the UE200. Specifically, the handover processing unit 120 performs the handover from the serving cell (source cell) of the UE200 to another neighboring cell (target cell). In particular, in this embodiment, the handover processing unit 120 may perform the handover in accordance with L1 / L2 mobility (LTM).

[0040] While a serving cell can simply be interpreted as the cell to which the UE200 is connected, more precisely, in the case of an RRC_CONNECTED UE without carrier aggregation (CA) configured, there is only one serving cell that constitutes the primary cell. In the case of an RRC_CONNECTED UE configured with CA, a serving cell can be interpreted as representing one or more sets of cells, including the primary cell and all secondary cells.

[0041] Furthermore, handovers may include conditional handovers (CHO) and / or dual active protocol stack (DAPS) handovers. A CHO allows a UE200-initiated handover to be performed when specific execution conditions are met. If a CHO is not applicable, a normal handover may be performed (which may be called a CHO recovery). In a CHO recovery, the UE200 performs cell selection after a CHO failure, but if a CHO candidate cell is selected, it can directly apply the conditional RRCReconfiguration to that cell and reconnect without sending an RRCReestablishmentRequest to the candidate target cell.

[0042] The execution conditions may consist of one or two trigger conditions (CHO events A3 / A5 as defined in 3GPP TS38.331). A single reference signal (RS) type may be triggered, and up to two different trigger quantities (e.g., Reference Signal Received Power (RSRP) and Reference Signal Received Quality (RSRQ), RSRP and Signal-to-Interference plus Noise power Ratio (SINR), etc.) may be set simultaneously for evaluation of the CHO execution conditions of a single candidate cell.

[0043] The measurement setting unit 130 performs the setting (measurement configuration) of the quality measurement of the serving cell and neighboring cells by the UE200. Specifically, the measurement setting unit 130 may perform the measurement configuration at Layer 3, or it may perform the measurement configuration at Layer 1 and / or Layer 2.

[0044] The measurement setting unit 130 can notify the UE 200 of the content of the measurement settings. The UE 200 may measure the quality of the serving cell and / or neighboring cells based on the notified measurement settings. The measurement setting unit 130 can receive a measurement report indicating the measurement result of the cell quality from the UE 200.

[0045] The control unit 140 controls each functional block constituting the gNB 100. In particular, in this embodiment, the control unit 140 can perform mobility control with the terminal. Specifically, the control unit 140 can perform not only mobility control according to L3 Mobility but also mobility control according to L1 / L2 Mobility (LTM).

[0046] Further, the control unit 140 can perform control as CU (source side or target side) or DU (source side or target side) in the gNB 100 having a CU-DU configuration.

[0047] (2.2) UE 200 As shown in FIG. 4, the UE 200 includes a wireless communication unit 210, an RLF / HO reporting unit 220, a handover execution unit 230, and a control unit 240.

[0048] The wireless communication unit 210 transmits an uplink signal (UL signal) according to NR. Also, the wireless communication unit 210 receives a downlink signal (DL signal) according to NR.

[0049] The RLF / HO reporting unit 220 performs processes related to radio link failure (RLF) and handover (HO) reporting. Specifically, the RLF / HO reporting unit 220 can transmit an RLF report to the network. Also, the RLF / HO reporting unit 220 can transmit a handover failure report and a successful handover report to the network.

[0050] An RLF report can be interpreted as a report of a failure related to the wireless link configured by the UE200. A handover failure report can be interpreted as a report of the situation when a handover to the target cell fails. A successful handover report can be interpreted as a report of the situation when a handover to the target cell is successful.

[0051] Furthermore, in the embodiment, the RLF report, handover failure report, and successful handover report may include information indicating the situation in the event of a handover failure.

[0052] In this way, the RLF / HO reporting unit 220 can transmit reports regarding handover to the network. In this embodiment, the RLF / HO reporting unit 220 may constitute a transmission unit.

[0053] The RLF / HO reporting unit 220 may transmit information regarding timing adjustment values ​​(TA values) to the network using at least one of such handover reports, namely an RLF report, a handover failure report, and a successful handover report. Specifically, the RLF / HO reporting unit 220 may transmit a report that includes type information indicating the type of TA value applied during a handover (HO).

[0054] The type information may indicate that the TA value HO'd by LTM is the TA value included in the cell switch command, or that it is the TA value calculated by the handover execution unit 230, that is, the TA value calculated by the UE200 itself. The TA value calculated by the UE200 itself may be interpreted as the TA value calculated by TA measurement, or more specifically, the TA value measured using the time difference in the reception timing of the signal to be measured (e.g., SSB) between the source cell of the transition and the target cell of the transition.

[0055] Thus, the RLF / HO reporting unit 220 may transmit a report that includes type information indicating that the timing adjustment value was obtained based on the cell switch command. Alternatively, the RLF / HO reporting unit 220 may transmit a report that includes type information indicating that the timing adjustment value was calculated by the UE200.

[0056] The RLF / HO reporting unit 220 may transmit a radio link failure report (RLF report), a handover failure report, or a successful handover report to the network, which includes at least one of the status, quality, or result of the handover in accordance with the LTM.

[0057] For example, the RLF / HO reporting unit 220 may send an RLF report, a handover failure report, or a successful handover report, which may include information on the status, quality, or result of the HO followed by the LTM, such as information on the target beam in which the HO failed, target cell identification information, SSB configuration, subcarrier spacing (SCS), received power, target cell / beam quality, and TCI state. The information elements included in the report will be described further below.

[0058] The RLF / HO reporting unit 220 may send a report (RLF report, handover failure report, or successful handover report) to the network that indicates that an uplink grant (configured UL Grant) is invalid if it is deemed not valid. An invalid UL Grant is considered to occur, for example, when the synchronous signal block (SSB) index associated with the configured UL Grant does not match the SSB index associated with the TCI state indicated by the cell switch command in accordance with the LTM. Such behavior is specified in 3GPP TS38.321.

[0059] Taking such operation into consideration, the RLF / HO reporting unit 220 may send a report to the network that includes an indication of whether the index of the synchronization signal block (SSB) associated with the UL Grant matches the index of the SSB associated with the cell switch command transmission setting indication (TCI).

[0060] The RLF / HO reporting unit 220 may send a report that includes an index of the SSB associated with the UL Grant. The RLF / HO reporting unit 220 may also send a report that includes an index of the SSB associated with the transmission setting display of the cell switch command.

[0061] The RLF / HO reporting unit 220 may send a report to the network that includes information indicating a handover failure due to the invalidity of the UL Grant. Specifically, the RLF / HO reporting unit 220 may send a report indicating that the failure cause is due to the configured UL Grant being invalid (not valid).

[0062] The RLF / HO reporting unit 220 can measure the quality of the UE200 serving cell and its neighboring cells, and report the measurement results (Measurement Report) to the network. The RLF / HO reporting unit 220 may perform measurement reporting of the source cell and target cell during handover.

[0063] The quality of the object being measured can be, for example, the quality included in the Measurement Report as defined in 3GPP TS38.331 (e.g., Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ)).

[0064] The handover execution unit 230 performs the handover of UE200. Specifically, the handover execution unit 230 may perform the handover to the destination cell (NG-RAN node) based on the control by gNB100.

[0065] Furthermore, the handover execution unit 230 can perform processing related to normal handover (legacy handover), conditional handover (CHO), and DAPS handover.

[0066] In the case of CHO, the handover execution unit 230 may transition to a candidate cell when the execution condition is met. The execution condition may be determined based on the quality of the reference signal (RS), specifically the values ​​of RSRP, RSRQ, or SINR, as described above.

[0067] Furthermore, the transition destination of CHO may or may not be accompanied by SCG. In other words, the cell to which CHO transitions may be a single cell, or it may consist of multiple cells (which may be interpreted as a cell group) according to DC.

[0068] Furthermore, the handover execution unit 230 may perform handovers based not only on L3 Mobility but also on L1 / L2 Mobility. Handover may be rephrased as transition, cell transition, cell selection, etc. Specifically, the handover execution unit 230 may perform a handover based on L1 / L2 Mobility based on at least one command from Layer 1 and / or Layer 2.

[0069] The type of command is not particularly limited, but for example, it may be an L1 / L2 Mobility command. This L1 / L2 Mobility command may be replaced with another command at the RRC layer.

[0070] Specifically, the handover execution unit 230 may send an RRC Reestablishment Request to the network (gNB100). Here, the RRC Reestablishment Request may be sent to the CU or the DU. Note that any message requesting reconnection at the RRC layer is not necessarily limited to an RRC Reestablishment Request; other messages (for example, an RRC Resume Request) may also be used.

[0071] Furthermore, the handover execution unit 230 may calculate the UE measured TA. The UE measured TA may be calculated using the time difference in the reception timing of the signal to be measured, such as SSB. Specifically, the handover execution unit 230 calculates the UE measured TA based on the time difference in the reception timing of the signal to be measured between the source cell and the target cell. Note that signals other than SSB may be used; for example, a reference signal such as CSI-RS may be used.

[0072] Thus, the handover execution unit 230 may calculate a timing adjustment value (TA value) based on the time difference in the reception timing of the signal to be measured between the source cell from which the handover originates and the target cell to which the handover destination occurs.

[0073] Furthermore, the handover execution unit 230 can receive the latest timing adjustment value of the source cell from the source cell in order to obtain a more accurate TA value of the source cell even when the UE200 is moving. In this embodiment, the handover execution unit 230 constitutes the receiving unit.

[0074] The handover execution unit 230 can calculate the UE measured TA using the latest value of the source cell's timing adjustment value.

[0075] The control unit 240 controls each functional block that makes up the UE200. Specifically, the control unit 240 can perform control related to the handover of the UE200.

[0076] Furthermore, the control unit 240 can perform L1 / L2 Mobility (LTM), that is, mobility control of at least one of Layer 1 and Layer 2. Mobility control by L1 / L2 Mobility may include quality measurement of the service area and neighboring cells in Layer 1 or Layer 2, setting of candidate cells for transition destinations, cell re-selection (transition), and handover. In this way, the control unit 240 can perform handover in accordance with mobility control by the lower layers.

[0077] Furthermore, the control unit 240 can select the destination cell if L1 / L2 Mobility (LTM) fails. Note that LTM failure may include failures in the measurement or handover procedure associated with cell transitions by LTM.

[0078] (3) Operation of the Wireless Communication System Next, the operation of the wireless communication system 10 will be described. Specifically, the operation related to RACH less HO in accordance with LTM will be described.

[0079] (3.1) Example of Operation 1 (3.1.1) Premise and Issues As described above, the wireless communication system 10 may perform RACH less HO in accordance with LTM. In addition, UE200 may calculate UE measured TA in order to perform RACH less HO.

[0080] Figure 5 shows an example of the measurement procedure for UE measured TA. As shown in Figure 5, UE measured TA can be expressed as (TA of target cell) = (TA of source cell) + (the time difference between the reception timing of the signal to be measured (such as SSB) in the source cell (current serving cell) and the timing of the signal to be measured in the target cell (candidate cell)).

[0081] The TA value of the source cell is known to the UE, and the UE can measure the difference in reception time between the source cell and the target cell to determine the TA value to be applied to the target cell. As mentioned above, in addition to SSB, reference signals such as CSI-RS can also be used.

[0082] In UE-measured TA, if the TA value on the source cell side is inaccurate—for example, if a certain amount of time has passed since the UE received the last TA command and the UE has moved during that time—the TA value of the target cell calculated using the method described above may also be inaccurate.

[0083] Applying such inaccurate TA values ​​may cause the UE to fail to hand over to the target cell. However, the UE cannot report such handover (HO) failures to the network. Furthermore, under the current 3GPP specifications, the UE cannot include details of such LTM-compliant HO failures in the RLF report, handover failure report, or successful handover report.

[0084] (3.1.2) Example of operation The UE may include the following information in at least one of the RLF report, handover failure report, and successful handover report.

[0085] - An indication showing whether the TA value applied to LTM is the TA value received by the cell switch command or the TA value calculated by the UE itself using TA measurement (UE measured TA). - If the TA value is calculated by TA measurement (UE measured TA), at least one of the following: the TA value of the target cell, the TA value of the source cell used in the calculation, and the time difference of the measured reception timing.

[0086] The UE may also report to the network a parameter indicating the age of the source cell's TA value used to calculate the target cell's TA value (for example, the time elapsed since the last time the TA value was received by the source cell via a TA command).

[0087] Furthermore, to ensure the accuracy of the source cell's TA value even when the UE is moving, the source cell (gNB) may send the latest TA value of the source cell to the UE using a TA command when instructing the UE to use the UE-measured TA, or immediately before handover. The UE may then perform the handover using the latest TA value and calculate the UE-measured TA (in this case, calculating the UE-measured TA is not mandatory).

[0088] Figure 6 shows an example sequence of an RLF report / handover failure report. Figure 7 shows an example sequence of a successful handover report. As shown in Figure 6, when a UE detects a radio link failure (RLF), it may send and receive RRC layer messages with the gNB and send an RRCRestablishmentComplete indicating that the RLF report / handover failure report is available. The UE may report the RLF report / handover failure report in the UE information response.

[0089] Furthermore, as shown in Figure 7, the UE may send an RRCRestablishmentComplete that indicates that successful HO information is available, and may report a successful handover report in the UE information response.

[0090] Furthermore, the ability to send RLF reports, handover failure reports, and successful HO information may also be notified to the gNB by other RRC layer messages (such as RRCSetupComplete, RRCReconfigurationComplete, RRCResumeComplete, etc.).

[0091] (3.2) Example of Operation 2 (3.2.1) Prerequisites and Issues In RACH-less HO (RACH-less LTM), the UE does not perform a random access procedure with the target cell during cell switching, that is, it does not send RACH. Therefore, it is necessary to pre-configure a UL Grant that sends RRC Reconfiguration Complete (i.e., pre-configure a configured UL Grant).

[0092] However, as mentioned above, the configured UL Grant may not be valid. In this case, the UE cannot send RRC Reconfiguration Complete because the Grant is not valid, and as a result, the handover may fail.

[0093] (3.2.2) Example of operation When RACH less HO is active and configured UL Grant is not enabled, the UE may send at least one of the following: an RLF report, a handover failure report, and a successful handover report, which include an indication that configured UL Grant is not enabled.

[0094] Furthermore, if a configured UL Grant is not enabled, the UE may include an indication in at least one of the RLF report, handover failure report, and successful handover report showing whether the SSB index associated with the configured UL Grant matches the SSB index associated with the TCI state in the LTM cell switch command. Alternatively, the UE may report this indication to the network (gNB) independently.

[0095] Furthermore, the UE may report the SSB index associated with the configured UL Grant, or the SSB index associated with the TCI state in the LTM cell switch command. In this case, either one of the SSB indexes may be reported, or both SSB indexes may be reported. Additionally, the TCI state ID or the SSB index associated with the TCI state ID may be reported.

[0096] Additionally, the UE may report a failure cause indicating that the configured UL Grant was not enabled.

[0097] (3.3) Example of operation 3 If the UE experiences the above-mentioned handover (HO) failure, it may include the following information in at least one of the RLF report, handover failure report, and successful handover report.

[0098] - Failed LTM target beams (beams on the target cell side) may include SSB index, CSI-RS index, and TCI-state ID.

[0099] - LTM target cell's condReconfigID (conditional reconfiguration ID) - Target cell / beam's LTM candidate ID or ltm-CandidatePCI (cell ID) - Target cell / beam's LTM SSB frequency - Target cell / beam's LTM subcarrier spacing - Received power of LTM target beam (SSB or CSI-RS) (whether received power exceeds a predetermined threshold) - LTM target cell / beam quality (RSRP, RSRQ, SINR) - Activation status of target cell / beam's Candidate cell TCI state (CandidateTCI-State or CandidateTCI-UL-State) (activated or deactivated) - Indication indicating whether RRC Reconfiguration Complete transmission using Configured UL Grant was retransmitted, and the number of retransmissions (if retransmission occurred) - Indication indicating whether cg-LTM-RetransmissionTimer has started - Indication indicating whether cg-LTM-RetransmissionTimer has expired - Number of times cg-LTM-RetransmissionTimer has expired - Time from LTM execution to LTM failure

[0100] The time from receiving a cell switch command to LTM failure, and in the case of UE-triggered LTM, the time from LTM execution by the UE to LTM failure, may be used as the target.

[0101] cg-LTM-RetransmissionTimer targets the period after the initial transmission (retransmission) of the Configured Grant (CG) in the HARQ (hybrid automatic repeat request) process at the LTM cell switch when the UE does not autonomously initiate retransmission in the HARQ process.

[0102] - Time from the start or completion of Early sync (synchronization procedure) to the execution of LTM - Time from the start or completion of Early sync to LTM failure

[0103] (3.4) Example of Operation 4 (3.4.1) Prerequisites and Issues In LTM, as in Conditional Handover (CHO), the UE may monitor the state according to specific execution conditions and execute LTM if the execution conditions are satisfied.

[0104] However, when applying such a Conditional LTM, it is unclear what should be reported to the network in the event of a Conditional LTM failure, and therefore the network cannot recognize the cause of the Conditional LTM handover (HO) failure.

[0105] (3.4.2) Example of Operation Conditional LTM may support events based on beam quality as execution conditions. For example, condEvent LTM3, condEvent LTM4, and condEvent LTM5 may be the following conditions: - CondEvent LTM3: Beam of candidate cell becomes amount of offset better than beam of serving cell - CondEvent LTM4: Beam of candidate cell becomes better than absolute threshold - CondEvent LTM5: Beam of serving cell becomes worse than absolute threshold1 AND Beam of candidate cell becomes better than another absolute threshold2 If any of these events are satisfied, the UE may report to the network.

[0106] If the UE experiences a Conditional LTM handover (HO) failure, it may include the information shown in Operation Example 3 above in at least one of the RLF report, handover failure report, and successful handover report, and may also include the following information. All or part of the information shown in Operation Example 3 and the following information may be understood to constitute information indicating the circumstances at the time of the handover failure.

[0107] - For Conditional LTMs, the execution conditions of the conditional LTM that have been satisfied (e.g., CondEvent LTM3, condEvent LTM4, condEvent LTM5) or the conditional LTM event ID.

[0108] - Time elapsed from receiving the LTM config until the LTM execution is executed (for example, when the execution conditions (e.g., CondEvent LTM3, condEvent LTM4, condEvent LTM5) are satisfied) - Time elapsed from when the LTM execution is executed (for example, when the execution conditions (e.g., CondEvent LTM3, condEvent LTM4, condEvent LTM5) are satisfied) until the LTM failure - Time elapsed from when the LTM execution is executed (for example, when the execution conditions (e.g., CondEvent LTM3, condEvent LTM4, condEvent LTM5) are satisfied) until the LTM fast failure recovery is successful Note that the aforementioned LTM failure or LTM fast failure recovery success can be understood as predetermined events. - Time elapsed from when the LTM failure occurs until the LTM fast failure recovery is successful

[0109] - Beam L1 quality per Beam ID: For example, the L1 quality of the Serving beam / cell (RSRP, RSRQ, SINR) for each SSBRI or CRI, the L1 quality of the target beam / cell (RSRP, RSRQ, SINR), and the L1 quality of the candidate beam / cell (RSRP, RSRQ, SINR) may be reported. In addition, for LTM for NR-DC, the L1 quality of the target PSCell / beam (for example, the L1 quality of the Serving PSCell beam / cell (RSRP, RSRQ, SINR) for each SSBRI or CRI, the L1 quality of the beam / cell of the target PSCell cell (RSRP, RSRQ, SINR), and the L1 quality of the beam / cell of the candidate PSCell (RSRP, RSRQ, SINR)) may be reported.

[0110] - If an LTM event (e.g., event LTM2, event LTM3, event LTM4, event LTM5) is satisfied, but the UE could not report the beam and its L1 quality for reasons exceeding the maximum number of reports (maximum N), for example, the L1 quality (RSRP, RSRQ, SINR) of the neighbor or candidate beam / cell / PSCell for each unreported SSBRI or CRI, this information may be reported to the base station in the UEInformationResponse message. Note that event LTM2, event LTM3, event LTM4, and event LTM5 may mean the following conditions (and so on): - Event LTM2: Beam of serving cell becomes worse than absolute threshold - Event LTM3: Beam of candidate cell becomes amount of offset better than beam of serving cell - Event LTM4: Beam of candidate cell becomes better than absolute threshold - Event LTM5: Beam of serving cell becomes worse than absolute threshold1 AND Beam of candidate cell becomes better than another absolute threshold2

[0111] - If the UE has a TA value or TA group for a Candidate cell / PSCell or target cell / PSCell, information indicating the elapsed time of the TA timer, whether the TA timer has expired or is still running, and whether the TA value is valid.

[0112] - Information indicating whether the UE has performed an early target cell notification; if an early target cell notification has been performed, the contents of the early target cell notification, such as target config ID(s) or target cell / PSCell / beam ID(s) or candidate cell / PScell / beam ID(s), DL / UL TCI state ID(s), TA value(s), information indicating whether early sync has been completed, and the conditions under which the early target cell notification was triggered (for example, a predetermined event (e.g., condEvent LTM3) has been satisfied). Note that the above information may also apply to LTM for NR-DC.

[0113] (4) Function and Effects As shown in the operation examples above, even when using UE measured TA, if a handover (HO) fails, the details of the HO failure can be reliably reported to the network. Also, even if a UL Grant applied to RACH-less HO is deemed invalid, the fact that the UL Grant is invalid can be reported to the network. For this reason, it is possible to contribute to the realization of SON related to LTM while utilizing RACH-less HO. Furthermore, even when Conditional LTM is applied, if a handover (HO) fails, the details of the HO failure can be reliably reported to the network.

[0114] (5) Other Embodiments Although embodiments have been described above, it will be obvious to those skilled in the art that the embodiments are not limited to those described and that various modifications and improvements are possible.

[0115] For example, the above example described a sequence between a UE and a gNB, but similar operations may also be performed between an IAB donor node and an IAB node (Mobile Termination (MT)) in an Integrated Access and Backhaul (IAB) where wireless access to terminals (User Equipment, UE) and wireless backhaul between wireless communication nodes such as base stations (gNB) are integrated.

[0116] In the above description, configure, activate, update, indicate, enable, specify, and select may be interpreted as interchangeable. Similarly, link, associate, correspond, and map may be interpreted as interchangeable, and allocate, assign, monitor, and map may also be interpreted as interchangeable.

[0117] Furthermore, "specific," "dedicated," "UE specific," and "UE individual" may be interpreted interchangeably. Similarly, "common," "shared," "group-common," "UE common," and "UE shared" may be interpreted interchangeably.

[0118] The block diagrams (Figures 3 and 4) used in the description of the embodiments above show functional units. These functional blocks (components) are realized by any combination of at least one of hardware and software. Furthermore, the method of realizing each functional block is not particularly limited. That is, each functional block may be realized using one device that is physically or logically coupled, or it may be realized using two or more physically or logically separated devices that are directly or indirectly connected (for example, using wired or wireless connections). A functional block may also be realized by combining software with the one or more of the above devices.

[0119] Functions include, but are not limited to, judgment, decision, judgment, calculation, calculation, processing, derivation, investigation, exploration, confirmation, reception, transmission, output, access, resolution, selection, selection, establishment, comparison, assumption, expectation, assumption, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating (mapping), and assigning. For example, a functional block (configuration part) that enables transmission is called a transmitting unit or transmitter. In any case, as mentioned above, the method of implementation is not particularly limited.

[0120] Furthermore, the gNB100 and UE200 (the device) described above may function as a computer that processes the wireless communication method of this disclosure. Figure 8 shows an example of the hardware configuration of the device. As shown in Figure 8, the device may be configured as a computer device including a processor 1001, memory 1002, storage 1003, communication device 1004, input device 1005, output device 1006, and bus 1007.

[0121] In the following explanation, the term "device" can be replaced with "circuit," "device," "unit," etc. The hardware configuration of the device may include one or more of the devices shown in the diagram, or it may be configured to omit some of the devices.

[0122] Each functional block of the device (see Figures 3 and 4) is implemented by any hardware element of the computer device, or a combination of such hardware elements.

[0123] Furthermore, each function in the device is realized by loading predetermined software (programs) onto hardware such as the processor 1001 and memory 1002, which allows the processor 1001 to perform calculations, control communication by the communication device 1004, and control at least one of the reading and writing of data in the memory 1002 and storage 1003.

[0124] The processor 1001 controls the entire computer, for example, by running an operating system. The processor 1001 may consist of a central processing unit (CPU) that includes interfaces with peripheral devices, control units, arithmetic units, registers, and so on.

[0125] Furthermore, the processor 1001 reads programs (program code), software modules, data, etc., from at least one of the storage 1003 and the communication device 1004 into the memory 1002 and executes various processes accordingly. The program used is one that causes the computer to execute at least a part of the operations described in the above embodiment. Moreover, the above-mentioned various processes may be executed by one processor 1001, or by two or more processors 1001 simultaneously or sequentially. The processor 1001 may be implemented by one or more chips. The program may also be transmitted from a network via a telecommunications line.

[0126] Memory 1002 is a computer-readable recording medium and may consist of at least one of the following: Read Only Memory (ROM), Erasable Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), Random Access Memory (RAM), etc. Memory 1002 may also be called a register, cache, main memory, etc. Memory 1002 can store a program (program code), software module, etc., that can execute a method according to one embodiment of this disclosure.

[0127] Storage 1003 is a computer-readable recording medium and may consist of at least one of the following: an optical disc such as a Compact Disc ROM (CD-ROM), a hard disk drive, a flexible disk, a magneto-optical disk (e.g., Compact Disc, Digital Multipurpose Disc, Blu-ray® Disc), a smart card, flash memory (e.g., a card, stick, key drive), a floppy® disk, a magnetic strip, etc. Storage 1003 may also be called an auxiliary storage device. The recording medium described above may also be, for example, a database, server, or other suitable medium including at least one of memory 1002 and storage 1003.

[0128] The communication device 1004 is hardware (transceiver / receiver device) for communicating between computers via at least one of a wired network and a wireless network, and is also referred to as a network device, network controller, network card, communication module, etc.

[0129] The communication device 1004 may be configured to include, for example, a high-frequency switch, a duplexer, a filter, a frequency synthesizer, etc., in order to implement at least one of frequency division duplex (FDD) and time division duplex (TDD).

[0130] The input device 1005 is an input device that accepts input from an external source (e.g., a keyboard, mouse, microphone, switch, button, sensor, etc.). The output device 1006 is an output device that outputs to an external source (e.g., a display, speaker, LED lamp, etc.). The input device 1005 and the output device 1006 may be configured as an integrated unit (e.g., a touch panel).

[0131] Furthermore, each device, such as the processor 1001 and the memory 1002, is connected by a bus 1007 for communicating information. The bus 1007 may be configured using a single bus, or different buses may be configured for each device.

[0132] Furthermore, the device may include hardware such as a microprocessor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a programmable logic device (PLD), and a field-programmable gate array (FPGA), and some or all of each functional block may be implemented by such hardware. For example, processor 1001 may be implemented using at least one of these hardware components.

[0133] Furthermore, notification of information is not limited to the embodiments described herein and may be carried out by other means. For example, notification of information may be carried out by physical layer signaling (e.g., Downlink Control Information (DCI), Uplink Control Information (UCI)), upper layer signaling (e.g., RRC signaling, Medium Access Control (MAC) signaling, broadcast information (Master Information Block (MIB), System Information Block (SIB))), other signals, or combinations thereof. RRC signaling may also be called RRC messages, and may be, for example, RRC Connection Setup messages, RRC Connection Reconfiguration messages, etc.

[0134] Each aspect / embodiment described herein may be applied to at least one of the following: Long Term Evolution (LTE), LTE-Advanced (LTE-A), SUPER 3G, IMT-Advanced, 4th generation mobile communication system (4G), 5th generation mobile communication system (5G), 6th generation mobile communication system (6G), xth generation mobile communication system (xG) (where x is, for example, an integer or decimal), Future Radio Access (FRA), New Radio (NR), W-CDMA®, GSM®, CDMA2000, Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi®), IEEE 802.16 (WiMAX®), IEEE 802.20, Ultra-WideBand (UWB), Bluetooth®, and other appropriate systems, as well as next-generation systems extended based thereon. Furthermore, multiple systems may be applied in combination (for example, a combination of at least one of LTE and LTE-A with 5G).

[0135] The processing procedures, sequences, flowcharts, etc., of each aspect / embodiment described in this disclosure may be reordered, provided they do not contradict each other. For example, the methods described in this disclosure present various step elements using exemplary order and are not limited to the specific order presented.

[0136] The specific operations described in this disclosure as being performed by a base station may, in some cases, be performed by its upper node. In a network consisting of one or more network nodes having a base station, it is clear that various operations performed for communication with a terminal can be performed by the base station and at least one other network node (for example, an MME or S-GW, but not limited to these). Although the above example illustrates the case where there is one other network node besides the base station, it may also be a combination of multiple other network nodes (for example, an MME and an S-GW).

[0137] Information and signals (such as data) can be output from a higher layer (or lower layer) to a lower layer (or higher layer). Input and output may occur via multiple network nodes.

[0138] Input and output information may be stored in a specific location (e.g., memory) or managed using a management table. Input and output information may be overwritten, updated, or appended to. Output information may be deleted. Input information may be sent to other devices.

[0139] The determination may be made by a value represented by one bit (0 or 1), by a boolean value (true or false), or by a numerical comparison (for example, a comparison with a predetermined value).

[0140] Each aspect / embodiment described in this disclosure may be used individually, in combination, or switched between as needed during implementation. Furthermore, notification of specific information (e.g., notification that "X is") is not limited to explicit notification, but may also be implicit (e.g., by not providing such notification).

[0141] Software should be broadly interpreted to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, execution threads, procedures, functions, and so on, whether they are called software, firmware, middleware, microcode, hardware description languages, or by any other name.

[0142] Furthermore, software, instructions, information, etc., may be transmitted and received via a transmission medium. For example, if software is transmitted from a website, server, or other remote source using at least one of wired technologies (such as coaxial cable, fiber optic cable, twisted pair, or Digital Subscriber Line (DSL)) and wireless technologies (such as infrared or microwave), then at least one of these wired and wireless technologies is included in the definition of a transmission medium.

[0143] The information, signals, etc. described in this disclosure may be represented using any of the various different technologies. For example, the data, instructions, commands, information, signals, bits, symbols, chips, etc. that may be referred to throughout the above description may be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, optical fields or photons, or any combination thereof.

[0144] In addition, terms used in this disclosure and terms necessary for understanding this disclosure may be replaced with terms having the same or similar meanings. For example, at least one of the channel and symbol may be a signal (signaling). Also, a signal may be a message. Furthermore, a component carrier (CC) may be called a carrier frequency, cell, frequency carrier, etc.

[0145] The terms “system” and “network” as used in this disclosure are interchangeable.

[0146] Furthermore, the information, parameters, etc., described in this disclosure may be expressed using absolute values, relative values ​​from a given value, or other corresponding information. For example, wireless resources may be indicated by an index.

[0147] The names used for the parameters described above are not restrictive in any way. Furthermore, the formulas and other expressions using these parameters may differ from those expressly disclosed in this disclosure. Since various channels (e.g., PUCCH, PDCCH, etc.) and information elements can be identified by any suitable name, the various names assigned to these various channels and information elements are not restrictive in any way.

[0148] In this disclosure, terms such as "Base Station (BS)," "wireless base station," "fixed station," "NodeB," "eNodeB (eNB)," "gNodeB (gNB)," "access point," "transmission point," "reception point," "transmission / reception point," "cell," "sector," "cell group," "carrier," and "component carrier" may be used interchangeably. Base stations may also be referred to by terms such as macrocell, small cell, femtocell, and picocell.

[0149] A base station can house one or more (e.g., three) cells (also called sectors). If a base station houses multiple cells, the entire coverage area of ​​the base station can be divided into multiple smaller areas, each of which can also be provided with communication services by a base station subsystem (e.g., a small indoor base station (Remote Radio Head: RRH)).

[0150] The terms "cell" or "sector" refer to a portion or all of the coverage area of ​​at least one of the base stations and base station subsystems that provide communication services in this coverage.

[0151] In this disclosure, the transmission of information by a base station to a terminal may be interpreted as the base station instructing the terminal to perform control or operation based on the information.

[0152] In this disclosure, terms such as "Mobile Station (MS)," "user terminal," "User Equipment (UE)," and "terminal" may be used interchangeably.

[0153] A mobile station may also be referred to by those skilled in the art as a subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, client, or some other appropriate term.

[0154] At least one of the base station and the mobile station may be called a transmitting device, a receiving device, a communication device, etc. At least one of the base station and the mobile station may also be a device mounted on a mobile body, the mobile body itself, etc. The mobile body may be a vehicle (e.g., a car, an airplane, etc.), an unmanned mobile body (e.g., a drone, an autonomous vehicle, etc.), or a robot (manned or unmanned). At least one of the base station and the mobile station may also be a device that does not necessarily move during communication operation. For example, at least one of the base station and the mobile station may be an Internet of Things (IoT) device such as a sensor.

[0155] Furthermore, the term "base station" in this disclosure may be interpreted as "mobile station" (user terminal, hereinafter the same). For example, the various aspects / embodiments of this disclosure may be applied to a configuration in which communication between a base station and a mobile station is replaced with communication between multiple mobile stations (which may be called, for example, Device-to-Device (D2D), Vehicle-to-Everything (V2X), etc.). In this case, the mobile station may have the functions that a base station has. Also, terms such as "uplink" and "downlink" may be interpreted as terms corresponding to terminal-to-terminal communication (for example, "side"). For example, uplink channel, downlink channel, etc. may be interpreted as side channel (or side link).

[0156] Similarly, the term "mobile station" in this disclosure may be interpreted as "base station." In this case, the base station may be configured to have the functions that a mobile station has.

[0157] A wireless frame may consist of one or more frames in the time domain. Each of these one or more frames in the time domain may be called a subframe. A subframe may further consist of one or more slots in the time domain. A subframe may have a fixed time length (e.g., 1 ms) that is independent of numerology.

[0158] Numerology may be communication parameters applied to at least one of the transmission and reception of a signal or channel. Numerology may include, for example, at least one of the following: subcarrier spacing (SCS), bandwidth, symbol length, cyclic prefix length, transmission time interval (TTI), number of symbols per TTI, radio frame configuration, specific filtering processes performed by the transceiver in the frequency domain, and specific windowing processes performed by the transceiver in the time domain.

[0159] A slot may consist of one or more symbols in the time domain (such as Orthogonal Frequency Division Multiplexing (OFDM) symbols or Single Carrier Frequency Division Multiple Access (SC-FDMA) symbols). A slot may also be a time unit based on neurology.

[0160] A slot may include multiple mini-slots. Each mini-slot may consist of one or more symbols in the time domain. Mini-slots may also be called sub-slots. Mini-slots may consist of fewer symbols than a slot. A PDSCH (or PUSCH) transmitted in a time unit larger than a mini-slot may be called PDSCH (or PUSCH) mapping type A. A PDSCH (or PUSCH) transmitted using a mini-slot may be called PDSCH (or PUSCH) mapping type B.

[0161] Wireless frames, subframes, slots, minislots, and symbols all represent units of time when transmitting a signal. Different names may be used for each of these terms.

[0162] For example, one subframe may be called a transmission time interval (TTI), multiple consecutive subframes may be called a TTI, or one slot or one minislot may be called a TTI. In other words, at least one of a subframe and a TTI may be a subframe in existing LTE (1ms), a period shorter than 1ms (e.g., 1-13 symbols), or a period longer than 1ms. Note that the unit representing the TTI may be called a slot, minislot, etc., instead of a subframe.

[0163] Here, TTI refers to, for example, the smallest unit of time for scheduling in wireless communication. For example, in an LTE system, the base station schedules each user terminal to allocate wireless resources (such as the frequency bandwidth and transmission power available to each user terminal) in TTI units. However, the definition of TTI is not limited to this.

[0164] TTI may be a transmission time unit for channel-encoded data packets (transport blocks), code blocks, code words, etc., or it may be a processing unit for scheduling, link adaptation, etc. Note that when a TTI is given, the actual time interval (e.g., number of symbols) in which the transport block, code block, code word, etc. are mapped may be shorter than the given TTI.

[0165] Furthermore, if one slot or one mini-slot is referred to as TTI, then one or more TTIs (i.e., one or more slots or one or more mini-slots) may constitute the minimum time unit of scheduling. In addition, the number of slots (number of mini-slots) that constitute the minimum time unit of scheduling may be controlled.

[0166] A TTI with a time length of 1ms may also be called a normal TTI, long TTI, normal subframe, long subframe, slot, etc. A TTI shorter than a normal TTI may also be called a shortened TTI, short TTI, partial or fractional TTI, shortened subframe, short subframe, mini slot, sub slot, slot, etc.

[0167] Furthermore, long TTIs (e.g., normal TTIs, subframes, etc.) may be interpreted as TTIs with a time length exceeding 1 ms, and short TTIs (e.g., shortened TTIs, etc.) may be interpreted as TTIs with a TTI length less than that of a long TTI but 1 ms or more.

[0168] A resource block (RB) is a resource allocation unit in the time domain and frequency domain, and in the frequency domain, it may contain one or more consecutive subcarriers. The number of subcarriers in an RB may be the same regardless of the neurology, for example, 12. The number of subcarriers in an RB may be determined based on the neurology.

[0169] Furthermore, the time domain of RB may contain one or more symbols and may be the length of one slot, one minislot, one subframe, or one TTI. One TTI, one subframe, etc., may each consist of one or more resource blocks.

[0170] One or more RBs may also be called a Physical RB (PRB), Sub-Carrier Group (SCG), Resource Element Group (REG), PRB pair, RB pair, etc.

[0171] Furthermore, a resource block may consist of one or more resource elements (REs). For example, one RE may be a radio resource area comprising one subcarrier and one symbol.

[0172] A Bandwidth Part (BWP), also known as a partial bandwidth, may represent a subset of consecutive common resource blocks (RBs) for a given neurology in a given carrier. Here, the common RBs may be identified by an index of the RBs relative to the carrier's common reference point. PRBs may be defined and numbered within a given BWP.

[0173] A BWP may include BWPs for UL (UL BWP) and BWPs for DL ​​(DL BWP). One or more BWPs may be set within a single carrier for a UE.

[0174] At least one of the configured BWPs may be active, and the UE does not need to assume that it will send or receive a given signal / channel outside of the active BWP. In this disclosure, terms such as "cell" and "carrier" may be read as "BWP".

[0175] The structures described above, such as wireless frames, subframes, slots, minislots, and symbols, are merely illustrative. For example, the number of subframes included in a wireless frame, the number of slots per subframe or wireless frame, the number of minislots included in a slot, the number of symbols and RBs included in a slot or minislot, the number of subcarriers included in an RB, and the number of symbols, symbol length, and cyclic prefix (CP) length within a TTI can be varied in various ways.

[0176] The terms “connected,” “coupled,” and any variations thereof mean any direct or indirect connection or coupling between two or more elements, and may include the presence of one or more intermediate elements between two elements that are “connected” or “coupled” with each other. The coupling or connection between elements may be physical, logical, or a combination thereof. For example, “connection” may be reinterpreted as “access.” As used in this disclosure, two elements may be considered to be “connected” or “coupled” with each other using at least one of one or more wires, cables, and printed electrical connections, and, in some non-limiting and non-exclusive examples, electromagnetic energy having wavelengths in the radio frequency domain, microwave domain, and optical (both visible and invisible) domain.

[0177] The reference signal can also be abbreviated as Reference Signal (RS), and may be called a pilot depending on the applicable standard.

[0178] In this disclosure, the phrase "based on" does not mean "based solely on" unless otherwise specified. In other words, the phrase "based on" means both "based solely on" and "based at least on."

[0179] In the configuration of each of the above devices, "means" may be replaced with "part," "circuit," "device," etc.

[0180] Any reference to elements using designations such as “First,” “Second,” etc., as used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient way to distinguish between two or more elements. Accordingly, references to the First and Second elements do not imply that only two elements may be employed therein, or that the First element must precede the Second element in any way.

[0181] Where the terms “include,” “including,” and variations thereof are used in this disclosure, these terms are intended to be inclusive, as is the term “comprising.” Furthermore, the term “or” as used in this disclosure is not intended to be exclusive OR.

[0182] In this disclosure, if articles are added through translation, such as a, an, and the in English, this disclosure may include the fact that the noun following these articles is plural.

[0183] As used in this disclosure, the terms “determining” and “determining” may encompass a wide variety of actions. “Determining” may include, for example, judging, calculating, computing, processing, deriving, investigating, looking up, searching, or inquiring (e.g., searching in a table, database, or other data structure), or ascertaining. “Determining” may also include receiving (e.g., receiving information), transmitting (e.g., sending information), inputting, outputting, or accessing (e.g., accessing data in memory). Furthermore, "judgment" and "decision" can include considering something as having "judgmented" or "decided" after resolving, selecting, choosing, establishing, comparing, etc. In other words, "judgment" and "decision" can include considering something as having "judgmented" or "decided" about some action. Also, "judgment (decision)" can be reinterpreted as "assuming," "expecting," or "considering."

[0184] In this disclosure, the term "A and B are different" may mean "A and B are different from each other." The term may also mean "A and B are each different from C." Terms such as "separate" and "combine" may be interpreted similarly to "different."

[0185] Figure 9 shows an example of the configuration of vehicle 2001. As shown in Figure 9, vehicle 2001 includes a drive unit 2002, a steering unit 2003, an accelerator pedal 2004, a brake pedal 2005, a shift lever 2006, left and right front wheels 2007, left and right rear wheels 2008, an axle 2009, an electronic control unit 2010, various sensors 2021 to 2029, an information service unit 2012, and a communication module 2013.

[0186] The drive unit 2002 consists of, for example, an engine, a motor, or a hybrid of an engine and a motor. The steering unit 2003 includes at least a steering wheel (also called a handle) and is configured to steer at least one of the front wheels and rear wheels based on the operation of the steering wheel operated by the user. The electronic control unit 2010 consists of a microprocessor 2031, memory (ROM, RAM) 2032, and communication ports (IO ports) 2033. Signals from various sensors 2021 to 2027 provided in the vehicle are input to the electronic control unit 2010. The electronic control unit 2010 may also be called an ECU (Electronic Control Unit).

[0187] Signals from various sensors 2021 to 2028 include current signals from the current sensor 2021 that senses motor current, front and rear wheel rotation speed signals obtained by the rotation speed sensor 2022, front and rear wheel air pressure signals obtained by the air pressure sensor 2023, vehicle speed signals obtained by the vehicle speed sensor 2024, acceleration signals obtained by the acceleration sensor 2025, accelerator pedal depression signals obtained by the accelerator pedal sensor 2029, brake pedal depression signals obtained by the brake pedal sensor 2026, shift lever operation signals obtained by the shift lever sensor 2027, and detection signals obtained by the object detection sensor 2028 for detecting obstacles, vehicles, pedestrians, etc.

[0188] The Information Services Unit 2012 consists of various devices for providing (outputting) various types of information such as driving information, traffic information, and entertainment information, including a car navigation system, audio system, speakers, television, and radio, and one or more ECUs that control these devices. The Information Services Unit 2012 uses information acquired from external devices via a communication module 2013, etc., to provide various multimedia information and multimedia services to the occupants of Vehicle 1.

[0189] Information Services Unit 2012 may include input devices that accept input from external sources (e.g., keyboards, mice, microphones, switches, buttons, sensors, touch panels, etc.) and output devices that perform output to external sources (e.g., displays, speakers, LED lamps, touch panels, etc.).

[0190] The driver assistance system unit 2030 consists of various devices that provide functions to prevent accidents or reduce the driver's workload, such as millimeter-wave radar, LiDAR (Light Detection and Ranging), cameras, positioning locators (e.g., GNSS), map information (e.g., high-definition (HD) maps, autonomous vehicle (AV) maps), gyro systems (e.g., IMU (Inertial Measurement Unit), INS (Inertial Navigation System)), AI (Artificial Intelligence) chips, and AI processors, as well as one or more ECUs that control these devices. The driver assistance system unit 2030 also sends and receives various information via the communication module 2013 to realize driver assistance functions or autonomous driving functions.

[0191] The communication module 2013 can communicate with the microprocessor 2031 and components of the vehicle 1 via its communication port. For example, the communication module 2013 sends and receives data via the communication port 2033 between the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, left and right front wheels 2007, left and right rear wheels 2008, axle 2009, the microprocessor 2031 and memory (ROM, RAM) 2032 in the electronic control unit 2010, and sensors 2021 to 2028 provided in the vehicle 2001.

[0192] The communication module 2013 is a communication device that can be controlled by the microprocessor 2031 of the electronic control unit 2010 and can communicate with external devices. For example, it can send and receive various types of information to and from external devices via wireless communication. The communication module 2013 may be located either inside or outside the electronic control unit 2010. The external device may be, for example, a base station or a mobile station.

[0193] The communication module 2013 may transmit at least one of the following to an external device via wireless communication: signals from the various sensors 2021 to 2028 input to the electronic control unit 2010, information obtained based on said signals, and information based on input from an external source (user) obtained via the information service unit 2012. The electronic control unit 2010, the various sensors 2021 to 2028, the information service unit 2012, etc., may also be called input units that accept input. For example, the PUSCH transmitted by the communication module 2013 may include information based on the above input.

[0194] The communication module 2013 receives various information (traffic information, signal information, vehicle-to-vehicle information, etc.) transmitted from an external device and displays it on the information service unit 2012 installed in the vehicle. The information service unit 2012 may also be called an output unit, which outputs information (for example, outputs information to devices such as displays and speakers based on the PDSCH (or data / information decoded from the PDSCH) received by the communication module 2013). The communication module 2013 also stores the various information received from the external device in a memory 2032 that is available to the microprocessor 2031. Based on the information stored in memory 2032, the microprocessor 2031 may control the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, left and right front wheels 2007, left and right rear wheels 2008, axles 2009, sensors 2021-2028, etc., installed in the vehicle 2001.

[0195] Although the present disclosure has been described in detail above, it will be clear to those skilled in the art that the present disclosure is not limited to the embodiments described herein. The present disclosure may be implemented in modified and altered forms without departing from the intent and scope of the present disclosure as defined by the claims. Accordingly, the descriptions in the present disclosure are for illustrative purposes only and are not intended to be restrictive in any way.

[0196] (Note) The disclosure described above may also be expressed as follows:

[0197] The first feature is that it comprises a control unit that performs a handover in accordance with mobility control by a lower layer, and a transmission unit that transmits a report on the handover to the network, wherein the transmission unit is a terminal that transmits the report, which includes type information indicating the type of timing adjustment value applied during the handover.

[0198] The second feature is that, in the first feature, the transmitting unit transmits the report including the type information indicating that it is the timing adjustment value obtained based on the cell switching command.

[0199] The third feature is that, in the first or second feature, the transmitting unit transmits the report including the type information indicating that it is the timing adjustment value calculated by the terminal.

[0200] The fourth feature is that, in the first to third features, the control unit calculates the timing adjustment value based on the time difference in the reception timing of the signal to be measured between the source cell from which the handover originates and the target cell to which the handover destination occurs.

[0201] The fifth feature is that, in the first to fourth features, the device includes a receiving unit that receives the latest value of the timing adjustment value of the source cell from the source cell, and the control unit calculates the timing adjustment value using the latest value.

[0202] The sixth feature is that, in the first to fifth features, the transmitting unit transmits a wireless link failure report, a handover failure report, or a handover success report to the network, which includes at least one of the status, quality, or result of the handover.

[0203] The seventh feature is a terminal comprising a control unit that performs a handover in accordance with mobility control by a lower layer, and a transmission unit that transmits a report regarding the handover to the network, wherein the transmission unit is a terminal that transmits the report including an indication that the uplink permission is invalid when the uplink permission that allows transmission on the uplink is deemed invalid.

[0204] The seventh feature is that, in the sixth feature, the transmitting unit transmits the report which includes a display indicating whether the index of the synchronization signal block associated with the uplink permission matches the index of the synchronization signal block associated with the transmission setting display of the cell switching command.

[0205] The eighth feature is that, in the sixth or seventh feature, the transmitting unit transmits the report including the index of the synchronization signal block associated with the uplink permission.

[0206] The ninth feature is that, in the sixth to eighth features, the transmitting unit transmits the report which includes an index of a synchronization signal block associated with the transmission setting display of the cell switching command.

[0207] The tenth feature is that, in the sixth to ninth features, the transmitting unit transmits the report which includes information indicating the failure of the handover due to the invalid uplink permission.

[0208] The eleventh feature is that, in the sixth to tenth features, the transmitting unit transmits a wireless link failure report, a handover failure report, or a handover success report to the network, which includes at least one of the status, quality, or result of the handover.

[0209] The twelfth feature is a control unit that performs a handover in accordance with mobility control by a lower layer, and a transmission unit that transmits a report regarding the handover to the network, wherein the transmission unit is a terminal that transmits the report, which includes information indicating the situation in the event of a handover failure.

[0210] The thirteenth feature is that, in the twelfth feature, the information indicating the situation includes information indicating the conditions for the handover that have been satisfied.

[0211] The fourteenth feature is that, in the twelfth feature, the information indicating the situation includes the elapsed time from when the handover execution conditions are satisfied until a predetermined event occurs.

[0212] The fifteenth feature is that, in the twelfth feature, the information indicating the situation includes at least one of the following: the quality of the source cell or beam from which the handover originates, the quality of the target cell or beam to which the handover destination lies, and the quality of the candidate cell or beam to which the handover destination lies.

[0213] The sixteenth feature is that, in the twelfth to fifteenth features, the transmitting unit transmits to the network a message that includes at least one of the following: a beam that satisfies the event conditions to be reported but has not been reported to the network, and the quality of the beam.

[0214] The seventeenth feature is a terminal communication method that includes the steps of performing a handover in accordance with mobility control by a lower layer, and transmitting a report regarding the handover to the network, which includes information indicating the situation in the event of a handover failure.

[0215] This application is based on Japanese Patent Application No. 2025-024590, filed on February 18, 2025. All of its contents are included here.

[0216] 10 Wireless communication system 20 NG-RAN 100 gNB 110 Wireless communication unit 120 Handover processing unit 130 Measurement setting unit 140 Control unit 200 UE 210 Wireless communication unit 220 RLF / HO reporting unit 230 Handover execution unit 240 Control unit 1001 Processor 1002 Memory 1003 Storage 1004 Communication device 1005 Input device 1006 Output device 1007 Bus 2001 Vehicle 2002 Drive unit 2003 Steering unit 2004 Accelerator pedal 2005 Brake pedal 2006 Shift lever 2007 Left and right front wheels 2008 Left and right rear wheels 2009 Axle 2010 Electronic control unit 2012 Information service unit 2013 Communication module 2021 Current sensor 2022 Rotation speed sensor 2023 Air pressure sensor 2024 Vehicle speed sensor 2025 Acceleration sensor 2026 Brake pedal sensor 2027 Shift lever sensor 2028 Object detection sensor 2029 Accelerator pedal sensor 2030 Driver assistance system unit 2031 Microprocessor 2032 Memory (ROM, RAM) 2033 Communication port

Claims

A control unit that performs a handover according to mobility control by the lower layer, The system includes a transmitting unit that transmits a report regarding the handover to the network, The transmitting unit is a terminal that transmits the report, which includes information indicating the situation in the event of a handover failure. 　 The terminal according to claim 1, wherein the information indicating the aforementioned situation includes information indicating the conditions for performing the handover that have been satisfied. 　 The terminal according to claim 1, wherein the information indicating the aforementioned situation includes the elapsed time from when the handover execution conditions are satisfied until a predetermined event occurs. 　 The terminal according to claim 1, wherein the information indicating the aforementioned situation includes at least one of the quality of the source cell or beam from which the handover originates, the quality of the target cell or beam to which the handover destination is located, and the quality of the candidate cell or beam to which the handover destination is located. 　 The terminal according to claim 1, wherein the transmitting unit transmits to the network a message containing at least one of the following: a beam that satisfies the event conditions to be reported but has not been reported to the network, and the quality of the beam. 　 The steps include: performing a handover according to mobility control by the lower layer, A terminal communication method comprising the step of sending a report concerning the handover to the network, which includes information indicating the circumstances in the event of a handover failure.

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