Terminal and communication method

Abstract

To provide a terminal and a communication method that can contribute to the realization of SON regarding LTM even when Conditional LTM is applied.SOLUTION: A terminal performs handover according to the mobility control by a lower layer. The terminal sends a report about the handover to a network. The report includes information indicating the situation when the handover has failed.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] The 3rd Generation Partnership Project (3GPP: registered trademark) is developing specifications for the 5th generation mobile communication system (5G, also known as New Radio (NR) or Next Generation (NG)), and is also developing specifications for the next generation, known as Beyond 5G, 5G Evolution, or 6G.

[0003] For example, 3GPP Release 18 is discussing extensions to Layer 1 / Layer 2 mobility (L1 / L2 mobility). L1 / L2 mobility, also known as Lower Layer Triggered Mobility (LTM), is a technology related to the mobility of terminals (User Equipment, UE) in Layer 1 or Layer 2, including the transition of UE to another cell (handover (HO)). HO using LTM is realized by lower layers such as the Medium Access Control layer (MAC).

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

[0005] In addition, in 3GPP Release 19, an extension of SON (Self-Organizing Networks) related to LTM is being considered (Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] "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 Summary of the Invention [Problem to be solved by the invention]

[0007] In LTM, like conditional handover (CHO), the UE monitors its status according to specific execution conditions, and if the execution conditions are satisfied, it may execute LTM (hereinafter referred to as conditional LTM). However, when Conditional LTM is applied, it is not clear what should be reported to the network when Conditional LTM fails, which poses a problem in that the network cannot identify the cause of the Conditional LTM handover (HO) failure.

[0008] Therefore, the following disclosure has been made in consideration of such circumstances, and aims to provide a terminal and a communication method that can contribute to realizing SON regarding LTM even when Conditional LTM is applied.

[0009] One aspect of the present disclosure is a terminal (UE 200) that includes a control unit (control unit 240) that executes handover in accordance with mobility control by a lower layer, and a transmission unit (RLF / HO reporting unit 220) that transmits a report regarding the handover to a network, the transmission unit transmitting the report including information indicating the situation when the handover fails.

[0010] One aspect of the present disclosure is a communication method for a terminal (UE200), including the steps of performing a handover in accordance with mobility control by a lower layer, and transmitting a report regarding the handover to a network, the report including information indicating the situation at the time of failure of the handover. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing the overall schematic configuration of a wireless communication system 10. As shown in FIG. [Figure 2] FIG. 2 is a diagram illustrating an example of control based on L1 / L2 mobility. [Figure 3] Figure 3 is a functional block diagram of gNB100. [Figure 4] FIG. 4 is a functional block diagram of the UE 200. [Figure 5] FIG. 5 is a diagram showing an example of a measurement procedure of the UE measured TA. [Figure 6] FIG. 6 is a diagram illustrating an example of a sequence of an RLF report / handover failure report. [Figure 7] FIG. 7 is a diagram illustrating an example of a sequence of a successful handover report. [Figure 8] FIG. 8 is a diagram showing an example of the hardware configuration of gNB100 and UE200. [Figure 9] FIG. 9 is a diagram showing an example of the configuration of a vehicle 2001. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments will be described with reference to the drawings. Note that the same or similar reference numerals are used to designate the same functions or configurations, and descriptions thereof will be omitted as appropriate.

[0013] (1) Overall configuration of wireless communication system 1 is a schematic diagram of the overall configuration of a wireless communication system 10 according to this embodiment. The wireless communication system 10 is a wireless communication system conforming to 5G New Radio (NR), and includes a Next Generation-Radio Access Network 20 (hereinafter, NG-RAN 20) and a terminal 200 (User Equipment 200, hereinafter, UE 200).

[0014] The wireless communication system 10 may be a wireless communication system conforming to a method called Beyond 5G, 5G Evolution, or 6G, or 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 Ultra-Reliable and Low Latency Communications (URLLC).

[0015] The NG-RAN 20 includes a radio base station 100 (hereinafter, gNB 100). Note that the specific configuration of the radio communication system 10, including the number of gNBs (or eNBs) and UEs, is not limited to the example shown in FIG. 1 .

[0016] The gNB 100 may also employ a fronthaul (FH) interface defined by the Open Radio Access Network Alliance (O-RAN). The gNB 100 may include an O-RAN Distributed Unit (O-DU) and an O-RAN Radio Unit (O-RU). The gNB 100 can function as a type of NG-RAN node.

[0017] The NG-RAN 20 actually includes multiple NG-RAN nodes, specifically, gNBs (or ng-eNBs), and is connected to a 5G core network (5GC, not shown). The NG-RAN 20 and 5GC may simply be referred to as a "network." In the 5GC, the concept of CUPS (Control and User Plane Separation) may be introduced, in which the functions of the user plane and the control plane are clearly separated.

[0018] The gNB100 is a radio base station conforming to NR, and performs radio communication conforming to NR with the UE200. The gNB100 may be configured to include a CU (Central Unit) and a DU (Distributed Unit), and the DU may be separated from the CU and installed in a different geographical location. One or more DUs may be connected to the CU. The gNB100 (gNB-CU) may be connected to each other via an Xn interface, and the CU and DU may be connected to each other via an F1 interface (such as an F1-AP). In this embodiment, the CU may be called a communication device or a central device. The DU may be called a distributed device.

[0019] The gNB100 and UE200 are capable of supporting Massive MIMO, which generates more directional beams by controlling radio signals transmitted from multiple antenna elements, Carrier Aggregation (CA), which bundles and uses multiple component carriers (CCs), and Dual Connectivity (DC), which enables simultaneous communication between the UE and multiple NG-RAN nodes.

[0020] The type of DC may be Multi-RAT Dual Connectivity (MR-DC), which uses multiple radio access technologies, or NR-NR Dual Connectivity (NR-DC), which uses only NR. For example, one gNB may constitute a master node (MN), and one or more other gNBs may constitute secondary nodes (SNs).

[0021] In the wireless communication system 10, not only mobility control of the UE 200 in layer 3 (which may be called L3 Mobility) but also mobility control in layer 1 and / or layer 2 (L1 / L2 Mobility) may be applied. L1 / L2 Mobility may be called LTM, and the name LTM will be mainly used hereinafter.

[0022] L3 Mobility may be interpreted as mobility control at the Radio Resource Control layer (RRC), while 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).

[0023] In addition, in UE-based LTM, like conditional handover (CHO), after the radio base station (gNB) receives a specific execution condition, the UE monitors the status according to the execution condition, and if the execution condition is satisfied, the UE may execute LTM.

[0024] Note that the LTM may include LTM fast failure recovery. LTM fast failure recovery is a mechanism in which, in the event of an LTM failure, the UE 200 performs cell selection, and if the selected cell is an LTM candidate cell, the UE 200 directly applies the configuration of the candidate cell without transmitting an RRCReestablishmentRequest to the gNB 100.

[0025] In the wireless communication system 10, handover (HO) without a random access procedure may be applied in LTM. Specifically, the UE 200 can perform RACH-less HO, which is HO without using a random access channel (RACH). RACH-less HO may also be referred to as RACH-less LTM.

[0026] In RACH less HO, the UE 200 can calculate a timing advance (TA) by using the time difference between the reception timing of a signal to be measured (e.g., SSB (Synchronization Signal) / PBCH (Physical Broadcast CHannel) Block) between a source cell (which may be interpreted as a serving cell) at the transition source (handover source) and a target cell (handover destination). Such a TA may be referred to as a UE measured TA.

[0027] In addition, in the case of RACH-less HO, an uplink grant (UL Grant) that allows the UE 200 to transmit an RRC message (RRC Reconfiguration Complete) after HO completion may be configured in advance. Such an UL Grant that is also applicable to RACH-less HO may be deemed invalid if certain conditions are met.

[0028] In a broad sense, the mobility of UE200 may mean the ease of movement and maneuverability of UE200, but in this embodiment, it may also mean minimizing call drops, radio link (including beam) failures, unnecessary handovers, ping-pong states, etc.

[0029] Figure 2 shows an example of control by L1 / L2 mobility. As shown in Figure 2, MAC included in the lower layer (Layer 1 / Layer 2), not RRC included in Layer 3, can perform measurement reporting, handover (HO) decision from a source cell to a target cell (which may include candidates), and timer management for determining whether HO is successful.

[0030] The MAC may report information related to the measurement report, the HO decision, etc. to a higher layer (RRC). The RRC may manage the state of radio resources accompanying the cell transition of the UE 200 based on the report.

[0031] In this embodiment, the channels include a control channel and a data channel. The control channels include a physical downlink control channel (PDCCH), a physical uplink control channel (PUCCH), a physical random access channel (PRACH), and a physical broadcast channel (PBCH).

[0032] The data channels include a PDSCH (Physical Downlink Shared Channel) and a PUSCH (Physical Uplink Shared Channel).

[0033] The reference signal includes a Demodulation Reference Signal (DMRS), a Sounding Reference Signal (SRS), a Phase Tracking Reference Signal (PTRS), and a Channel State Information-Reference Signal (CSI-RS), and the signal includes a channel and a reference signal. Furthermore, the data may refer to data transmitted via a data channel.

[0034] (2) Functional block configuration of wireless communication system Next, a functional block configuration of the wireless communication system 10 will be described. Specifically, the functional block configurations of the gNB 100 and the UE 200 will be described. Fig. 3 is a functional block configuration diagram of the gNB 100. Fig. 4 is a functional block configuration diagram of the UE 200.

[0035] (2.1) gNB100 As shown in FIG. 3, the gNB 100 includes a radio communication unit 110, a handover processing unit 120, a measurement setting unit 130, and a control unit 140.

[0036] The wireless communication unit 110 transmits downlink signals (DL signals) conforming to NR, and also receives uplink signals (UL signals) conforming to NR.

[0037] The TCI state can provide information on antenna ports that are substantially co-located (quasi-collocated: QCL) with the antenna ports of the PDCCH. If the UE 200 has a specific control resource set (CORESET) that is spatially co-located with a specific CSI-RS, the UE 200 can determine which beam is appropriate when attempting to receive the PDCCH using the CORESET. Note that the QCL / TCI state / beam may be interpreted interchangeably.

[0038] The handover processing unit 120 executes handover of the UE 200. Specifically, the handover processing unit 120 executes handover from a serving cell (source cell) of the UE 200 to another nearby cell (target cell). In particular, in this embodiment, the handover processing unit 120 may execute handover in accordance with L1 / L2 mobility (LTM).

[0039] The serving cell may be simply interpreted as the cell to which the UE 200 is connected, but more precisely, in the case of an RRC_CONNECTED UE in which carrier aggregation (CA) is not configured, there is only one serving cell that constitutes the primary cell. In the case of an RRC_CONNECTED UE configured using CA, the serving cell may be interpreted as indicating a set of one or more cells including the primary cell and all secondary cells.

[0040] The handover may also include a conditional handover (CHO) and / or a dual active protocol stack (DAPS) handover. CHO can execute a handover initiated by the UE 200 when a specific execution condition is met. If CHO is not applicable, a normal handover may be executed (which may be called CHO recovery). In CHO recovery, the UE 200 executes cell selection after a CHO failure. If a CHO candidate cell is selected, the UE 200 can directly apply conditional RRCReconfiguration of the selected cell to reconnect without transmitting an RRCRestablishmentRequest to the candidate target cell.

[0041] The execution condition may consist of one or two trigger conditions (CHO event A3 / A5 specified 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 simultaneously set for evaluation of the CHO execution condition for a single candidate cell.

[0042] The measurement configuration unit 130 performs configuration (measurement configuration) of quality measurements of the serving cell and neighboring cells by the UE 200. Specifically, the measurement configuration unit 130 may perform measurement configuration in layer 3, or may perform measurement configuration in layer 1 and / or layer 2.

[0043] The measurement configuration unit 130 can notify the contents of the measurement configuration to the UE 200. The UE 200 can measure the quality of the serving cell and / or neighboring cells based on the notified measurement configuration. The measurement configuration unit 130 can receive a measurement report from the UE 200 indicating the measurement result of the cell quality.

[0044] 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).

[0045] In addition, the control unit 140 can perform control as a CU (source side or target side) or a DU (source side or target side) in a gNB100 having a CU-DU configuration.

[0046] (2.2)UE200 As shown in FIG. 4, the UE 200 includes a radio communication unit 210, an RLF / HO reporting unit 220, a handover executing unit 230, and a control unit 240.

[0047] The wireless communication unit 210 transmits an uplink signal (UL signal) conforming to NR. The wireless communication unit 210 also receives an uplink signal (DL signal) conforming to NR.

[0048] The RLF / HO reporting unit 220 performs processing 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. The RLF / HO reporting unit 220 can also transmit a handover failure report and a successful handover report to the network.

[0049] The RLF report may be interpreted as a report of a failure related to a radio link established by the UE 200. The handover failure report may be interpreted as a report of a situation when handover to the target cell fails. The successful handover report may be interpreted as a report of a situation when handover to the target cell is successful. In addition, in the embodiment, any of the RLF report, handover failure report, and successful handover report may include information indicating the situation at the time of handover failure.

[0050] In this way, the RLF / HO reporting unit 220 can send a report regarding the handover to the network. In this embodiment, the RLF / HO reporting unit 220 may constitute a sending unit.

[0051] The RLF / HO reporting unit 220 may transmit information about the timing adjustment value (TA value) to the network using such a report about handover, i.e., at least one of an RLF report, a handover failure report, and a successful handover report. Specifically, the RLF / HO reporting unit 220 may transmit a report including type information indicating the type of TA value applied at the time of handover (HO).

[0052] The type information may indicate that the TA value obtained by HO using LTM is a TA value included in a cell switch command, or that the TA value is calculated by the handover executing unit 230, that is, calculated by the UE 200 itself. The TA value calculated by the UE 200 itself may be interpreted as a TA value calculated by TA measurement, more specifically, a TA value measured using the time difference between the reception timings of a signal to be measured (e.g., SSB) between a source cell at the handover source and a target cell at the handover destination.

[0053] In this way, RLF / HO reporting section 220 may transmit a report including type information indicating that the timing adjustment value is acquired based on the cell switch command. Alternatively, RLF / HO reporting section 220 may transmit a report including type information indicating that the timing adjustment value is calculated by UE 200.

[0054] The RLF / HO reporting unit 220 may send a radio link failure report (RLF report), a handover failure report or a successful handover report to the network, which report includes at least one of the status, quality or result of the handover according to the LTM.

[0055] For example, the RLF / HO reporting unit 220 may transmit an RLF report, a handover failure report, or a successful handover report, which may include information on the target beam for which HO failed, the target cell's identification information, SSB configuration, subcarrier spacing (SCS), received power, target cell beam quality, TCI state, etc. The information elements included in the report will be described in more detail below.

[0056] When an uplink grant that allows transmission in the uplink (UL) is deemed invalid, the RLF / HO reporting unit 220 may transmit to the network a report (RLF report, handover failure report, or successful handover report) including an indication that the uplink grant (configured UL Grant) is invalid. The UL Grant may be deemed invalid, for example, when the synchronization 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 according to the LTM. Such an operation is specified in 3GPP TS38.321.

[0057] Taking such an operation into consideration, the RLF / HO reporting unit 220 may transmit a report to the network including 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 transmission configuration indicator (TCI) of the cell switch command.

[0058] The RLF / HO reporting unit 220 may transmit a report including an index of an SSB associated with the UL Grant. Also, the RLF / HO reporting unit 220 may transmit a report including an index of an SSB associated with the transmission setting indication of the cell switch command.

[0059] The RLF / HO reporting unit 220 may transmit to the network a report including information indicating a handover failure caused by the UL Grant being invalid. Specifically, the RLF / HO reporting unit 220 may transmit a report indicating a failure caused by the configured UL Grant being invalid (not valid) as the failure cause.

[0060] The RLF / HO reporting unit 220 can measure the quality of the serving cell of the UE 200 and neighboring cells of the serving cell and report the measurement results (Measurement Report) to the network. The RLF / HO reporting unit 220 can perform measurement reporting of the source cell and the target cell during handover.

[0061] The quality to be measured may be, for example, the quality included in the Measurement Report specified in 3GPP TS38.331 (e.g., Reference Signal Received Power (RSRP) and Reference Signal Received Quality (RSRQ)).

[0062] The handover execution unit 230 executes handover of the UE 200. Specifically, the handover execution unit 230 may execute handover to a transfer destination cell (NG-RAN node) based on control by the gNB 100.

[0063] In addition, the handover execution unit 230 can execute processes related to normal handover (legacy handover), conditional handover (CHO), and DAPS handover.

[0064] In the case of CHO, the handover execution unit 230 may transition to the candidate cell when an execution condition is satisfied. As described above, the execution condition may be determined based on the quality of the reference signal (RS), specifically, the value of RSRP, RSRQ, or SINR.

[0065] In addition, the destination of the CHO may or may not be accompanied by an SCG. In other words, the destination cell of the CHO may be a single cell or may be composed of multiple cells (which may be read as a cell group) according to the DC.

[0066] Furthermore, the handover execution unit 230 may execute handover based on not only L3 mobility but also L1 / L2 mobility. Handover may be interpreted as transition, cell transition, cell selection, etc. Specifically, the handover execution unit 230 may execute handover based on L1 / L2 mobility based on at least one command of layer 1 and / or layer 2.

[0067] The type of the command is not particularly limited, but may be, for example, an L1 / L2 Mobility command. The L1 / L2 Mobility command may be replaced with another command of the RRC layer.

[0068] Specifically, the handover executing unit 230 may transmit an RRC Reestablishment Request to the network (gNB 100). Here, the destination of the RRC Reestablishment Request may be a CU or a DU. Note that the message is not necessarily limited to an RRC Reestablishment Request, and may be another message (for example, an RRC Resume Request) as long as it is a message requesting reconnection in the RRC layer.

[0069] Furthermore, the handover executor 230 may calculate a UE measured TA. The UE measured TA may be calculated using a time difference between the reception timings of a measurement target signal such as an SSB. Specifically, the handover executor 230 calculates the UE measured TA based on a time difference between the reception timings of a measurement target signal between the source cell and the target cell. Note that a signal other than an SSB may also be used, for example, a reference signal such as a CSI-RS may also be used.

[0070] In this way, the handover executing unit 230 may calculate the timing advance value (TA value) based on the time difference between the reception timing of the measurement target signal between the source cell of the handover source and the target cell of the handover destination.

[0071] Furthermore, the handover executing unit 230 can also receive the latest value of the timing adjustment value of the source cell from the source cell in order to make the TA value of the source cell more accurate even when the UE 200 is moving, etc. In this embodiment, the handover executing unit 230 constitutes a receiving unit.

[0072] The handover execution unit 230 can calculate the UE measured TA using the latest timing adjustment value of the source cell.

[0073] The control unit 240 controls each functional block constituting the UE 200. Specifically, the control unit 240 can execute control relating to handover of the UE 200.

[0074] Furthermore, the control unit 240 can execute 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 service areas and neighboring cells in layer 1 or layer 2, setting of destination candidate cells, cell reselection (transition), handover, etc. In this way, the control unit 240 can execute handover in accordance with mobility control by lower layers.

[0075] Furthermore, the control unit 240 can select a cell as a transfer destination when L1 / L2 Mobility (LTM) fails (LTM failure). Note that an LTM failure may include a failure in a measurement or transfer (handover) procedure accompanying a cell transfer by LTM.

[0076] (3) Operation of the wireless communication system Next, a description will be given of the operation of the wireless communication system 10. Specifically, a description will be given of the operation related to RACH less HO according to LTM.

[0077] (3.1) Example 1 (3.1.1) Prerequisites and Issues As described above, RACH less HO according to LTM may be performed in the wireless communication system 10. Furthermore, the UE 200 may calculate a UE measured TA in order to perform RACH less HO.

[0078] Figure 5 shows an example of a measurement procedure for UE measured TA. As shown in Figure 5, UE measured TA may be expressed as (target cell TA) = (source cell TA) + (time difference between the reception timing of the signal to be measured (e.g., SSB) in the source cell (current serving cell) and the reception timing of the signal to be measured in the target cell (candidate cell)).

[0079] The TA value of the source cell is known to the UE, and the UE can measure the reception time difference between the source cell and the target cell and 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.

[0080] In the case of 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 by the above-mentioned method may also be inaccurate.

[0081] If such an inaccurate TA value is applied, the UE may fail to handover to the target cell. However, the UE cannot report such a handover (HO) failure situation to the network. Furthermore, in the current 3GPP specifications, the UE cannot include the content of such an HO failure according to the LTM in the RLF report, handover failure report, and successful handover report.

[0082] (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:

[0083] An indication of whether the TA value applied to the LTM is the TA value received in the cell switch command or the TA value calculated by the UE itself through TA measurement (UE measured TA). In the case of a TA value calculated by TA Measurement (UE measured TA), at least one of the TA value of the target cell, the TA value of the source cell used in the calculation, and the time difference between the measured reception timing The UE may also report to the network a parameter indicating the age of the TA value of the source cell used to calculate the TA value of the target cell (for example, the elapsed time since the TA value was received by the previous TA command in the source cell). In addition, to ensure the accuracy of the TA value on the source cell side even when the UE is moving, the source cell (gNB) may transmit the latest TA value of the source cell to the UE using a TA command when instructing the UE measured TA to the UE or immediately before handover. The UE may perform handover using the latest value of the TA and may calculate the UE measured TA (in this case, calculation of the UE measured TA may not be required).

[0084] 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 transmit and receive RRC layer messages with a gNB and transmit an RRCRestablishmentComplete message including an indication that an RLF report / handover failure report is available for transmission. The UE may report the RLF report / handover failure report in a UE information response.

[0085] Also, as shown in FIG. 7, the UE may send an RRCR establishment complete including an indication that successful HO information is available for transmission, and report a successful handover report in the UE information response.

[0086] In addition, the gNB may be notified by other RRC layer messages (RRCSetupComplete, RRCReconfigurationComplete, RRCResumeComplete, etc.) that it is possible to transmit an RLF report / handover failure report / successful HO information.

[0087] (3.2) Example 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, i.e., does not transmit RACH, so it is necessary to pre-configure the UL Grant for sending RRC Reconfiguration Complete (i.e., pre-configure the configured UL Grant).

[0088] However, as described above, the configured UL Grant may not be valid. In this case, the UE may not be able to send the RRC Reconfiguration Complete because the Grant is not valid, which may result in a handover failure.

[0089] (3.2.2) Example of operation During RACH less HO, if the configured UL Grant is not valid, the UE may transmit at least one of an RLF report, a handover failure report, and a successful handover report including an indication that the configured UL Grant is not valid.

[0090] Furthermore, when the configured UL Grant is not valid, the UE may include an indication indicating whether an SSB index associated with the configured UL Grant matches an SSB index associated with the TCI state in the LTM cell switch command in at least one of the RLF report, the handover failure report, and the successful handover report. Alternatively, the UE may report the indication independently to the network (gNB).

[0091] The UE may report an SSB index associated with the configured UL grant, or may report an SSB index associated with the TCI state in the TM cell switch command. In this case, either one of the SSB indexes may be reported, or both SSB indexes may be reported. Alternatively, the UE may report the TCI state ID or an SSB index associated with the TCI state ID.

[0092] Furthermore, the UE may report a failure cause that indicates that the failure is caused by the configured UL Grant not being valid.

[0093] (3.3) Example 3 When the UE experiences the above-mentioned handover (HO) failure, the UE may include the following information in at least one of the RLF report, the handover failure report, and the successful handover report:

[0094] -Failed LTM target beam (beam on the target cell side) May include SSB index, CSI-RS index, and TCI-state ID.

[0095] LTM target cell condReconfigID (conditional reconfiguration ID) LTM candidate ID or ltm-CandidatePCI (cell ID) of the target cell / beam LTM SSB frequency of target cell / beam LTM subcarrier spacing of target cells / beams - Received power of LTM target beam (SSB or CSI-RS) (whether the received power exceeds a predetermined threshold) LTM target cell / beam quality (RSRP, RSRQ, SINR) Activation status (activated or deactivated) of the target cell / beam's Candidate cell TCI state (CandidateTCI-State or CandidateTCI-UL-State) Indication of whether or not to retransmit RRC Reconfiguration Complete using Configured UL Grant, and the number of retransmissions (if retransmission occurs) Indication of whether the cg-LTM-RetransmissionTimer has started An indication of whether the cg-LTM-RetransmissionTimer has expired Number of times cg-LTM-RetransmissionTimer expired Time from LTM execution to LTM failure The time from receiving the cell switch command to LTM failure, and in the case of UE triggered LTM, the time from the UE executing LTM to LTM failure may be targeted.

[0096] The cg-LTM-RetransmissionTimer covers the period after the transmission (retransmission) of the Configured Grant (CG) of the hybrid automatic repeat request (HARQ) process for the initial transmission at the LTM cell switch when the UE does not autonomously initiate retransmissions in the HARQ process.

[0097] Time from the start or completion of the Early sync (synchronization procedure) to the execution of the LTM Time from the start or completion of Early sync to LTM failure

[0098] (3.4) Example 4 (3.4.1) Prerequisites and Issues In LTM, like conditional handover (CHO), the UE may monitor its state according to a specific execution condition, and execute LTM when the execution condition is satisfied. However, when applying such Conditional LTM, it is not clear what should be reported to the network when Conditional LTM fails, and therefore the network cannot recognize the cause of the Conditional LTM handover (HO) failure.

[0099] (3.4.2) Example of operation Conditional LTM execution conditions may support events based on beam quality. 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 met, the UE may report to the network.

[0100] When a UE experiences a Conditional LTM handover (HO) failure, the UE may include the information shown in the above-described Operation Example 3 in at least one of the RLF report, handover failure report, and successful handover report, and may further include the following information. It may be understood that all or part of the information shown in Operation Example 3 and the following information constitute information indicating the situation at the time of handover failure.

[0101] For Conditional LTM, the condition that was satisfied (e.g., CondEvent LTM3, condEvent LTM4, condEvent LTM5) or the conditional LTM event ID

[0102] The time elapsed from receiving the LTM config until the LTM execution is executed (for example, the execution conditions (for example, CondEvent LTM3, condEvent LTM4, condEvent LTM5) are satisfied). The time elapsed from when an LTM execution is executed (for example, when the execution conditions (for example, CondEvent LTM3, condEvent LTM4, condEvent LTM5) are satisfied) to when an LTM failure occurs The time elapsed from when an LTM execution is executed (for example, when the execution conditions (for example, CondEvent LTM3, condEvent LTM4, condEvent LTM5) are satisfied) to when an LTM fast failure recovery is successful The aforementioned LTM failure or successful LTM fast failure recovery may be understood as a predetermined event. The time elapsed from the occurrence of an LTM failure to the successful LTM fast failure recovery

[0103] Beam L1 quality by beam ID For example, the L1 quality (RSRP, RSRQ, SINR) of the serving beam / cell for each SSBRI or CRI, the L1 quality (RSRP, RSRQ, SINR) of the target beam / cell, and the L1 quality (RSRP, RSRQ, SINR) of the candidate beam / cell may be reported. Also, in the case of LTM for NR-DC, the L1 quality of the target PSCell / beam (e.g., the L1 quality (RSRP, RSRQ, SINR) of the serving PSCell beam / cell for each SSBRI or CRI, the L1 quality (RSRP, RSRQ, SINR) of the beam / cell of the target PSCell cell, and the L1 quality (RSRP, RSRQ, SINR) of the beam / cell of the candidate PSCell) may be reported.

[0104] If an LTM event (e.g., event LTM2, event LTM3, event LTM4, event LTM5) is satisfied but the number of beams and beam L1 qualities that the UE could not report due to reasons exceeding the number that can be reported (maximum N), for example, the L1 qualities (RSRP, RSRQ, SINR) of neighbor or candidate beams / cells / PSCells for each SSBRI or CRI that could not be reported For example, this information may be reported to the base station in a UEInformationResponse message. Note that event LTM2, event LTM3, event LTM4, and event LTM5 may mean the following conditions (the same applies hereinafter). - 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

[0105] When the UE is concerned with the TA value or TA group of the candidate cell / PSCell or target cell / PSCell, the elapsed time of the TA timer, information indicating whether the TA timer has expired or is running, and information indicating whether the TA value is valid

[0106] Information indicating whether the UE performed early target cell notification, and if so, the content of the early target cell notification For example, 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 condition under which the early target cell notification was triggered (for example, a specified event (for example, condEvent LTM3) has been satisfied). Note that the above information may also be applied in the case of LTM for NR-DC.

[0107] (4) Actions and Effects According to the operation example described above, even when UE-measured TA is used, if handover (HO) fails, the HO failure status and other information can be reliably reported to the network. Furthermore, even if an UL Grant applied to RACH-less HO is deemed invalid, the fact that the UL Grant is invalid can be reported to the network. This can contribute to realizing SON related to LTM while using RACH-less HO. Furthermore, even when Conditional LTM is applied, if handover (HO) fails, the HO failure status and other information can be reliably reported to the network.

[0108] (5) Other embodiments Although the embodiments have been described above, it will be obvious to those skilled in the art that the present invention is not limited to the description of the embodiments and that various modifications and improvements are possible.

[0109] For example, in the above-mentioned operation example, an example sequence between a UE and a gNB was described, 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) that integrates wireless access to a terminal (User Equipment, UE) and wireless backhaul between wireless communication nodes such as a radio base station (gNB).

[0110] In the above description, configure, activate, update, indicate, enable, specify, and select may be interchangeable. Similarly, link, associate, correspond, and map may be interchangeable, and allocate, assign, monitor, and map may be interchangeable.

[0111] Furthermore, specific, dedicated, UE-specific, and UE-dedicated may be interchangeable. Similarly, common, shared, group-common, UE-common, and UE-shared may be interchangeable.

[0112] The block diagrams (FIGS. 3 and 4) used in the description of the above-described embodiments show functional blocks. 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 a single device that is physically or logically coupled, or may be realized using two or more physically or logically separated devices that are connected directly or indirectly (for example, by wire, wirelessly, etc.) and these multiple devices. The functional block may also be realized by combining software with the single device or multiple devices.

[0113] Functions include, but are not limited to, judgment, determination, judgment, calculation, computation, processing, derivation, investigation, search, confirmation, reception, transmission, output, access, resolution, selection, election, establishment, comparison, assumption, expectation, consideration, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating, mapping, and assignment. For example, a functional block (component) that performs transmission is called a transmitting unit or transmitter. As mentioned above, there are no particular limitations on how each is implemented.

[0114] Furthermore, the above-described gNB100 and UE200 (the device) may function as a computer that performs processing of the wireless communication method of the present disclosure. Figure 8 is a diagram showing 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, a memory 1002, a storage 1003, a communication device 1004, an input device 1005, an output device 1006, a bus 1007, etc.

[0115] In the following description, the term "apparatus" can be interpreted as a circuit, a device, a unit, etc. The hardware configuration of the apparatus may be configured to include one or more of the apparatuses shown in the drawings, or may be configured to exclude some of the apparatuses.

[0116] Each functional block of the device (see FIGS. 3 and 4) is realized by any hardware element of the computer device or a combination of the hardware elements.

[0117] In addition, each function of the device is realized by loading specified software (programs) onto hardware such as processor 1001 and memory 1002, causing processor 1001 to perform calculations, control communication via communication device 1004, and control at least one of reading and writing data in memory 1002 and storage 1003.

[0118] The processor 1001 controls the entire computer by running, for example, an operating system, and may be configured as a central processing unit (CPU) including an interface with peripheral devices, a control unit, an arithmetic unit, a register, and the like.

[0119] The processor 1001 also reads programs (program codes), 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 in accordance with these. The programs used are those that cause a computer to execute at least some of the operations described in the above-mentioned embodiments. Furthermore, the various processes described above may be executed by one processor 1001, or may be executed simultaneously or sequentially by two or more processors 1001. The processor 1001 may be implemented by one or more chips. The programs may be transmitted from a network via a telecommunications line.

[0120] The memory 1002 is a computer-readable recording medium and may be configured by, for example, at least one of a read-only memory (ROM), an erasable programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM), a random access memory (RAM), etc. The memory 1002 may also be called a register, a cache, a main memory (primary storage device), etc. The memory 1002 can store a program (program code), a software module, etc., that can execute a method according to an embodiment of the present disclosure.

[0121] Storage 1003 is a computer-readable recording medium, and may be, for example, at least one of an optical disk such as a Compact Disc ROM (CD-ROM), a hard disk drive, a flexible disk, a magneto-optical disk (e.g., a compact disk, a digital versatile disk, a Blu-ray disc), a smart card, a flash memory (e.g., a card, a stick, a key drive), a floppy disk, a magnetic strip, etc. Storage 1003 may also be referred to as an auxiliary storage device. The above-mentioned recording medium may be, for example, a database, a server, or other appropriate medium including at least one of memory 1002 and storage 1003.

[0122] The communication device 1004 is hardware (transmission / reception device) for communicating between computers via at least one of a wired network and a wireless network, and is also called, for example, a network device, a network controller, a network card, or a communication module.

[0123] The communication device 1004 may be configured to include a high-frequency switch, a duplexer, a filter, a frequency synthesizer, etc. to realize, for example, at least one of Frequency Division Duplex (FDD) and Time Division Duplex (TDD).

[0124] The input device 1005 is an input device (for example, a keyboard, a mouse, a microphone, a switch, a button, a sensor, etc.) that receives input from the outside. The output device 1006 is an output device (for example, a display, a speaker, an LED lamp, etc.) that outputs to the outside. The input device 1005 and the output device 1006 may be integrated into one device (for example, a touch panel).

[0125] Furthermore, each device such as the processor 1001 and the memory 1002 is connected to a bus 1007 for communicating information. The bus 1007 may be configured using a single bus, or may be configured using different buses between each device.

[0126] Furthermore, the device may be configured to include hardware such as a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a programmable logic device (PLD), or a field programmable gate array (FPGA), and some or all of the functional blocks may be realized by the hardware. For example, the processor 1001 may be implemented using at least one of these pieces of hardware.

[0127] Furthermore, the notification of information is not limited to the aspects / embodiments described in the present disclosure, and may be performed using other methods. For example, the notification of information may be performed by physical layer signaling (e.g., Downlink Control Information (DCI), Uplink Control Information (UCI)), higher layer signaling (e.g., RRC signaling, Medium Access Control (MAC) signaling, broadcast information (Master Information Block (MIB), System Information Block (SIB))), other signals, or a combination thereof. Furthermore, the RRC signaling may be referred to as an RRC message, and may be, for example, an RRC Connection Setup message, an RRC Connection Reconfiguration message, or the like.

[0128] Each aspect / embodiment described in the present disclosure may be applied to at least one of a system using Long Term Evolution (LTE), LTE-Advanced (LTE-A), SUPER 3G, IMT-Advanced, a 4th generation mobile communication system (4G), a 5th generation mobile communication system (5G), a 6th generation mobile communication system (6G), an xth generation mobile communication system (xG) (where x is, for example, an integer or a decimal), Future Radio Access (FRA), New Radio (NR), W-CDMA (registered trademark), GSM (registered trademark), CDMA2000, Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi (registered trademark)), IEEE 802.16 (WiMAX (registered trademark)), IEEE 802.20, Ultra-WideBand (UWB), Bluetooth (registered trademark), or other suitable systems, and next-generation systems enhanced based on these. In addition, a combination of multiple systems (for example, a combination of at least one of LTE and LTE-A with 5G) may be applied.

[0129] The order of the procedures, sequences, flowcharts, etc. of each aspect / embodiment described in this disclosure may be changed unless it is consistent. For example, the methods described in this disclosure present elements of various steps using an example order, and are not limited to the particular order presented.

[0130] In the present disclosure, a specific operation described as being performed by a base station may also be performed by its upper node in some cases. 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 may be performed by at least one of the base station and another network node other than the base station (for example, an MME or an S-GW, etc., but are not limited to these). Although the above example illustrates a case where there is one other network node other than the base station, a combination of multiple other network nodes (for example, an MME and an S-GW) may also be used.

[0131] Information, signals (information, etc.) may be output from a higher layer (or a lower layer) to a lower layer (or a higher layer), or may be input / output via multiple network nodes.

[0132] Input and output information may be stored in a specific location (for example, memory) or may be managed using a management table. Input and output information may be overwritten, updated, or added to. Output information may be deleted. Input information may be sent to another device.

[0133] The determination may be made based on a value represented by one bit (0 or 1), a Boolean value (true or false), or a numerical comparison (e.g., comparison with a predetermined value).

[0134] Each aspect / embodiment described in this disclosure may be used alone, in combination, or switched depending on the implementation. Furthermore, notification of predetermined information (e.g., notification that "X is true") is not limited to being done explicitly, but may be done implicitly (e.g., by not notifying the predetermined information).

[0135] Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

[0136] Software, instructions, information, etc. may also be transmitted or received over a transmission medium. For example, if software is transmitted from a website, server, or other remote source using wired technologies (such as coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL)), and / or wireless technologies (such as infrared, microwave), then these wired and / or wireless technologies are included within the definition of transmission media.

[0137] The information, signals, etc. described in this disclosure may be represented using any of a variety of different technologies. For example, data, instructions, commands, information, signals, bits, symbols, chips, etc. that may be referred to throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or magnetic particles, optical fields or photons, or any combination thereof.

[0138] Note that terms explained 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 a channel and a symbol may be a signal (signaling). Furthermore, a signal may be a message. Furthermore, a component carrier (CC) may be called a carrier frequency, a cell, a frequency carrier, etc.

[0139] As used in this disclosure, the terms "system" and "network" are used interchangeably.

[0140] Furthermore, the information, parameters, etc. described in the present disclosure may be expressed using absolute values, may be expressed using relative values ​​from a predetermined value, or may be expressed using other corresponding information. For example, a radio resource may be indicated by an index.

[0141] The names used for the above-described parameters are not intended to be limiting in any way. Furthermore, the mathematical expressions using these parameters may differ from those explicitly disclosed in this disclosure. The various channels (e.g., PUCCH, PDCCH, etc.) and information elements may be identified by any suitable names, and therefore the various names assigned to these various channels and information elements are not intended to be limiting in any way.

[0142] In this disclosure, terms such as "base station (BS)," "radio 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.

[0143] A base station can accommodate one or more (e.g., three) cells (also called sectors). When a base station accommodates multiple cells, the overall coverage area of ​​the base station can be divided into multiple smaller areas, and each smaller area can be provided with communication services by a base station subsystem (e.g., a small indoor base station (Remote Radio Head: RRH)).

[0144] The terms "cell" or "sector" refer to part or all of the coverage area of ​​a base station and / or base station subsystem that provides communication services within that coverage area.

[0145] In the present disclosure, the base station transmitting information to a terminal may be interpreted as the base station instructing the terminal to control or operate based on the information.

[0146] In this disclosure, the terms "Mobile Station (MS)," "user terminal," "User Equipment (UE)," "terminal," etc. may be used interchangeably.

[0147] 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 suitable terminology.

[0148] 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 be a device mounted on a mobile object, or the mobile object itself. The mobile object may be a vehicle (e.g., a car, an airplane, etc.), an unmanned mobile object (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 include devices that do not necessarily move during communication operations. 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.

[0149] Furthermore, a base station in the present disclosure may be interpreted as a mobile station (user terminal, the same applies hereinafter). For example, the aspects / embodiments of the present 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) or Vehicle-to-Everything (V2X)). In this case, the mobile station may be configured to have the functions of a base station. Furthermore, terms such as "uplink" and "downlink" may be interpreted as terms corresponding to communication between terminals (for example, "side"). For example, terms such as an uplink channel and a downlink channel may be interpreted as a side channel (or side link).

[0150] Similarly, a mobile station in the present disclosure may be interpreted as a base station, in which case the base station may have the functions of a mobile station.

[0151] A radio frame may be composed of one or more frames in the time domain. Each of the one or more frames in the time domain may be called a subframe. A subframe may further be composed 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.

[0152] Numerology may be a communication parameter applied to at least one of transmission and reception of a signal or channel, such as subcarrier spacing (SCS), bandwidth, symbol length, cyclic prefix length, transmission time interval (TTI), number of symbols per TTI, radio frame structure, specific filtering operations performed by a transceiver in the frequency domain, and specific windowing operations performed by a transceiver in the time domain.

[0153] A slot may consist of one or more symbols in the time domain (such as an Orthogonal Frequency Division Multiplexing (OFDM) symbol, a Single Carrier Frequency Division Multiple Access (SC-FDMA) symbol, etc.) A slot may be a numerology-based time unit.

[0154] A slot may include multiple minislots. Each minislot may consist of one or more symbols in the time domain. A minislot may also be called a subslot. A minislot may consist of fewer symbols than a slot. A PDSCH (or PUSCH) transmitted in a time unit larger than a minislot may be called PDSCH (or PUSCH) mapping type A. A PDSCH (or PUSCH) transmitted using a minislot may be called PDSCH (or PUSCH) mapping type B.

[0155] The radio frame, subframe, slot, minislot, and symbol all represent time units for transmitting signals, and may be referred to by other names corresponding to the radio frame, subframe, slot, minislot, and symbol.

[0156] 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. That is, at least one of the subframe and the TTI may be a subframe (1 ms) in existing LTE, a period shorter than 1 ms (e.g., 1-13 symbols), or a period longer than 1 ms. Note that the unit representing the TTI may be called a slot, minislot, etc., instead of a subframe.

[0157] Here, TTI refers to, for example, the smallest time unit for scheduling in wireless communication. For example, in an LTE system, a base station performs scheduling to allocate radio resources (such as frequency bandwidth and transmission power that can be used by each user terminal) to each user terminal in TTI units. However, the definition of TTI is not limited to this.

[0158] The TTI may be a transmission time unit for a channel-encoded data packet (transport block), a code block, a code word, etc., or may be a processing unit for scheduling, link adaptation, etc. When a TTI is given, the time interval (e.g., the number of symbols) to which a transport block, a code block, a code word, etc. is actually mapped may be shorter than the TTI.

[0159] When one slot or one minislot is called a TTI, one or more TTIs (i.e., one or more slots or one or more minislots) may be the minimum time unit for scheduling. Also, the number of slots (minislots) constituting the minimum time unit for scheduling may be controlled.

[0160] A TTI having a time length of 1 ms may be called a regular TTI (TTI in LTE Rel. 8-12), normal TTI, long TTI, regular subframe, normal subframe, long subframe, slot, etc. A TTI shorter than a regular TTI may be called a shortened TTI, short TTI, partial or fractional TTI, shortened subframe, short subframe, minislot, subslot, slot, etc.

[0161] In addition, a long TTI (e.g., a normal TTI, a subframe, etc.) may be interpreted as a TTI having a time length of more than 1 ms, and a short TTI (e.g., a shortened TTI, etc.) may be interpreted as a TTI having a TTI length shorter than the TTI length of a long TTI and equal to or greater than 1 ms.

[0162] A resource block (RB) is a resource allocation unit in the time domain and frequency domain, and may include one or more consecutive subcarriers in the frequency domain. The number of subcarriers included in an RB may be the same regardless of numerology, for example, 12. The number of subcarriers included in an RB may also be determined based on numerology.

[0163] The time domain of an RB may include one or more symbols and may be one slot, one minislot, one subframe, or one TTI in length. Each TTI, subframe, etc. may be composed of one or more resource blocks.

[0164] Note that one or more RBs may also be called a physical resource block (PRB), a sub-carrier group (SCG), a resource element group (REG), a PRB pair, an RB pair, or the like.

[0165] Furthermore, a resource block may be composed of one or more resource elements (REs). For example, one RE may be a radio resource region of one subcarrier and one symbol.

[0166] A Bandwidth Part (BWP) (which may also be referred to as a fractional bandwidth) may represent a subset of contiguous common resource blocks (RBs) for a given numerology on a given carrier, where the common RBs may be identified by their index relative to a common reference point of the carrier. PRBs may be defined in a given BWP and numbered within that BWP.

[0167] The BWP may include a BWP for UL (UL BWP) and a BWP for DL ​​(DL BWP). One or more BWPs may be configured for a UE within one carrier.

[0168] At least one of the configured BWPs may be active, and the UE may not expect to transmit or receive a given signal / channel outside the active BWP. Note that the terms "cell," "carrier," etc. in this disclosure may be read as "BWP."

[0169] The above-described structures of the radio frame, subframe, slot, minislot, and symbol are merely examples. For example, the number of subframes included in a radio frame, the number of slots per subframe or radio 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, the number of symbols in a TTI, the symbol length, the cyclic prefix (CP) length, and other configurations can be changed in various ways.

[0170] The terms "connected," "coupled," or any variation thereof, refer to 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" to each other. The coupling or connection between elements may be physical, logical, or a combination thereof. For example, "connected" may be read as "access." As used in this disclosure, two elements may be considered to be "connected" or "coupled" to each other using one or more wires, cables, and / or printed electrical connections, as well as electromagnetic energy having wavelengths in the radio frequency range, microwave range, and optical (both visible and invisible) range, as some non-limiting and non-exhaustive examples.

[0171] The reference signal may also be abbreviated as Reference Signal (RS), and may also be called a pilot depending on the applicable standard.

[0172] As used in this disclosure, the phrase "based on" does not mean "based only on," unless expressly stated otherwise. In other words, the phrase "based on" means both "based only on" and "based at least on."

[0173] The "means" in the configuration of each of the above devices may be replaced with "part," "circuit," "device," etc.

[0174] As used in this disclosure, any reference to an element using a designation such as "first," "second," etc. does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient method of distinguishing between two or more elements. Thus, a reference to a first and a second element does not imply that only two elements may be employed therein or that the first element must precede the second element in some way.

[0175] When used in this disclosure, the terms "include," "including," and variations thereof are intended to be inclusive, similar to the term "comprising." Furthermore, when used in this disclosure, the term "or" is not intended to be an exclusive or.

[0176] In this disclosure, where articles are added by translation, such as a, an, and the in English, the disclosure may include that the nouns following these articles are in the plural form.

[0177] As used in this disclosure, the terms "determining" and "determining" may encompass a wide variety of actions. "Determining" and "determining" may include, for example, judging, calculating, computing, processing, deriving, investigating, looking up, searching, inquiring (e.g., searching in a table, database, or other data structure), ascertaining, and the like. "Determining" and "determining" may also include receiving (e.g., receiving information), transmitting (e.g., sending information), input, output, accessing (e.g., accessing data in memory), and the like. Furthermore, "judgment" and "decision" can include regarding resolving, selecting, choosing, establishing, comparing, etc. as having been "judged" or "decided." In other words, "judgment" and "decision" can include regarding some action as having been "judged" or "decided." Furthermore, "judgment (decision)" can be interpreted as "assuming," "expecting," "considering," etc.

[0178] In the present 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 "coupled" may also be interpreted in the same way as "different."

[0179] 9 shows an example of the configuration of a vehicle 2001. As shown in FIG. 9, the 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.

[0180] The drive unit 2002 is composed 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 the rear wheels based on the operation of the steering wheel operated by the user. The electronic control unit 2010 is composed of a microprocessor 2031, a memory (ROM, RAM) 2032, and a communication port (IO port) 2033. Signals are input to the electronic control unit 2010 from various sensors 2021 to 2027 provided in the vehicle. The electronic control unit 2010 may also be called an ECU (Electronic Control Unit).

[0181] The signals from the various sensors 2021 to 2028 include a current signal from a current sensor 2021 that senses the current of the motor, a rotation speed signal of the front and rear wheels obtained by a rotation speed sensor 2022, an air pressure signal of the front and rear wheels obtained by an air pressure sensor 2023, a vehicle speed signal obtained by a vehicle speed sensor 2024, an acceleration signal obtained by an acceleration sensor 2025, an accelerator pedal depression amount signal obtained by an accelerator pedal sensor 2029, a brake pedal depression amount signal obtained by a brake pedal sensor 2026, a shift lever operation signal obtained by a shift lever sensor 2027, and a detection signal for detecting obstacles, vehicles, pedestrians, etc. obtained by an object detection sensor 2028.

[0182] The information service unit 2012 is composed of various devices, such as a car navigation system, an audio system, speakers, a television, and a radio, for providing (outputting) various types of information, such as driving information, traffic information, and entertainment information, and one or more ECUs for controlling these devices. The information service unit 2012 provides various types of multimedia information and multimedia services to the occupants of the vehicle 1 by using information acquired from external devices via the communication module 2013, etc.

[0183] The information service unit 2012 may include input devices (e.g., keyboards, mice, microphones, switches, buttons, sensors, touch panels, etc.) that accept input from the outside, and may also include output devices (e.g., displays, speakers, LED lamps, touch panels, etc.) that output to the outside.

[0184] The driving assistance system unit 2030 is composed of various devices that provide functions for preventing accidents and reducing the driver's driving burden, such as millimeter-wave radar, LiDAR (Light Detection and Ranging), cameras, positioning locators (e.g., GNSS, etc.), map information (e.g., high-definition (HD) maps, autonomous vehicle (AV) maps, etc.), gyro systems (e.g., IMU (Inertial Measurement Unit), INS (Inertial Navigation System), etc.), AI (Artificial Intelligence) chips, and AI processors, as well as one or more ECUs that control these devices. The driving assistance system unit 2030 also transmits and receives various information via the communication module 2013 to realize driving assistance functions or autonomous driving functions.

[0185] The communication module 2013 can communicate with the microprocessor 2031 and components of the vehicle 1 via the communication port. For example, the communication module 2013 transmits and receives data via the communication port 2033 to and from 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, a microprocessor 2031 and memory (ROM, RAM) 2032 in the electronic control unit 2010, and sensors 2021 to 2028, which are provided in the vehicle 2001.

[0186] 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 an external device. For example, it transmits and receives various information to and from the external device 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, a mobile station, or the like.

[0187] The communication module 2013 may transmit at least one of signals from the above-mentioned various sensors 2021-2028 input to the electronic control unit 2010, information obtained based on the signals, and information based on input from the outside (user) obtained via the information service unit 2012 to an external device via wireless communication. The electronic control unit 2010, the various sensors 2021-2028, the information service unit 2012, etc. may be referred to as input units that accept input. For example, the PUSCH transmitted by the communication module 2013 may include information based on the above-mentioned input.

[0188] The communication module 2013 receives various information (traffic information, traffic signal information, vehicle-to-vehicle information, etc.) transmitted from external devices and displays it on an information service unit 2012 provided in the vehicle. The information service unit 2012 may be called an output unit that outputs information (for example, outputs information to a device such as a display or speaker 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 external devices in a memory 2032 that can be used by the microprocessor 2031. Based on the information stored in the memory 2032, the microprocessor 2031 may control 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, sensors 2021 to 2028, and the like provided in the vehicle 2001.

[0189] Although the present disclosure has been described in detail above, it is clear to those skilled in the art that the present disclosure is not limited to the embodiments described herein. The present disclosure can be implemented in modified and altered forms without departing from the spirit and scope of the present disclosure as defined by the claims. Therefore, the description of the present disclosure is intended to be illustrative and does not have any limiting meaning on the present disclosure.

[0190] (Addendum) The above disclosure may be expressed as follows:

[0191] A first feature is a terminal that includes a control unit that executes a handover in accordance with mobility control by a lower layer, and a transmission unit that transmits a report regarding the handover to a network, wherein the transmission unit transmits the report including type information that indicates a type of timing adjustment value that is applied during the handover.

[0192] A second feature based on the first feature is that the transmitter transmits the report including the type information indicating that the timing adjustment value is acquired based on a cell switching command.

[0193] A third feature based on the first or second feature is that the transmitter transmits the report including the type information indicating that the timing advance value is calculated by the terminal.

[0194] A fourth feature is any one of the first to third features, wherein the control unit calculates the timing adjustment value based on a time difference between reception timings of a signal to be measured in a source cell of a handover source and a target cell of a handover destination.

[0195] A fifth feature, in any of the first to fourth features, includes a receiving unit that receives a latest value of a timing adjustment value of the source cell from the source cell, and the control unit calculates the timing adjustment value using the latest value.

[0196] A sixth feature is that in any one of the first to fifth features, the transmitter transmits to the network a radio link failure report, a handover failure report, or a handover success report including at least one of a status, quality, or result related to the handover.

[0197] A seventh feature is a terminal including: a control unit that executes handover in accordance with mobility control by a lower layer; and a transmission unit that transmits a report regarding the handover to a network, wherein the transmission unit transmits the report including an indication that the uplink permission that permits transmission in an uplink is invalid when the uplink permission is deemed invalid.

[0198] A seventh feature is, in the sixth feature, the transmitter transmits the report including an indication indicating whether an index of a synchronization signal block associated with the uplink grant matches an index of a synchronization signal block associated with a transmission setting indication of a cell switching command.

[0199] According to an eighth feature based on the sixth or seventh feature, the transmitter transmits the report including an index of a synchronization signal block associated with the uplink grant.

[0200] According to a ninth feature, in any one of the sixth to eighth features, the transmitter transmits the report including an index of a synchronization signal block associated with a transmission setting indication of a cell switching command.

[0201] A tenth feature, based on any one of the sixth to ninth features, is that the transmitter transmits the report including information indicating a failure of the handover due to the uplink grant being invalid.

[0202] An eleventh feature is, in the sixth to tenth features, the transmitter transmits to the network a radio link failure report, a handover failure report, or a handover success report including at least one of a status, quality, or result related to the handover.

[0203] A twelfth feature is a terminal including a control unit that executes handover in accordance with mobility control by a lower layer, and a transmission unit that transmits a report regarding the handover to a network, wherein the transmission unit transmits the report including information indicating a situation when the handover fails.

[0204] The thirteenth feature based on the twelfth feature is that the information indicating the status includes information indicating a condition for executing the handover that has been satisfied.

[0205] According to a fourteenth feature based on the twelfth feature, the information indicating the status includes an elapsed time from when the execution condition for handover is satisfied until a predetermined event occurs.

[0206] A 15th feature is, in the 12th feature, that the information indicating the situation includes at least one of a quality of a source cell or beam of a handover source, a quality of a target cell or beam of a handover destination, and a quality of a candidate cell or beam of a handover destination.

[0207] A 16th feature is that, in the 12th to 15th features, the transmitter transmits a message to the network including at least one of a beam that has satisfied an event condition to be reported but has not been reported to the network and the quality of the beam.

[0208] A seventeenth feature is a communication method for a terminal, the method including: performing a handover in accordance with mobility control by a lower layer; and transmitting, to a network, a report regarding the handover, the report including information indicating a situation when the handover fails. [Explanation of symbols]

[0209] 10. Wireless communication systems 20 NG-RAN 100 gNB 110 Radio Communication Department 120 Handover processing unit 130 Measurement setting section 140 Control Unit 200 UE 210 Radio Communication Department 220 RLF / HO Reporting Department 230 Handover Execution Department 240 Control Unit 1001 processor 1002 memory 1003 Storage 1004 Communication equipment 1005 Input Device 1006 Output Device 1007 Bus 2001 Vehicle 2002 Drive unit 2003 Steering Section 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 Services Department 2013 Communication Module 2021 Current Sensor 2022 RPM 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 Driving Assistance Systems Department 2031 microprocessor 2032 memory (ROM, RAM) 2033 communication port

Claims

1. a control unit that executes handover according to mobility control by a lower layer; a transmitter for transmitting a report regarding the handover to a network; The transmission unit transmits the report including information indicating a situation at the time of the handover failure.

2. The terminal according to claim 1 , wherein the information indicating the status includes information indicating a condition for executing the handover that has been satisfied.

3. The terminal according to claim 1 , wherein the information indicating the status includes an elapsed time from when the execution condition for handover is satisfied until a predetermined event occurs.

4. The terminal according to claim 1 , wherein the information indicating the status includes at least one of the quality of a source cell or beam of a handover source, the quality of a target cell or beam of a handover destination, and the quality of a candidate cell or beam of a handover destination.

5. The terminal according to claim 1 , wherein the transmitter transmits a message to the network including at least one of a beam that has satisfied an event condition to be reported but has not been reported to the network and the quality of the beam.

6. performing a handover according to mobility control by a lower layer; A communication method for a terminal, comprising: transmitting a report regarding the handover to a network, the report including information indicating a situation at the time of the handover failure.

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