Radio base station and wireless communication method

Abstract

This radio base station comprises: a first device; and one or more second devices that are connected to the first device. The second device controls transition of a terminal to a candidate cell in accordance with mobility control by a lower layer. The second device transmits, to the first device, cell switching information including at least one of identification information of a transmission configuration indication state of the candidate cell, an index of a beam that is transmitted by the second device, and a group of timing adjustment values associated with the transmission configuration indication state.

Description

Radio base station and radio communication method

[0001] The present disclosure relates to a radio base station and a radio communication method that support LTM (L1 / L2 mobility).

[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 19 discusses extensions to Layer 1 / Layer 2 mobility (L1 / L2 mobility, specifically, Lower Layer Triggered Mobility (LTM)) (see Non-Patent Document 1). LTM is a technology related to the mobility of a terminal (User Equipment, UE) in Layer 1 or Layer 2, and includes the transition of a UE to another cell (handover (HO)). HO using LTM is realized by a lower layer such as the Medium Access Control layer (MAC).

[0004] In the LTM specified in 3GPP Release-18, when a radio base station is configured with a CU (Central Unit, first device) and a DU (Distributed Unit, second device), the UE transmits a Layer 1 measurement report (L1 measurement report) to the Source DU. The Source DU selects a cell (or beam) with good quality included in the L1 measurement report and determines a candidate cell (beam) for the LTM. The Source DU then instructs the UE to select the candidate cell (beam) using a Cell Switch Command (MAC-CE).

[0005] In addition, 3GPP is considering a system in which the Source CU determines candidate cells (beams) for LTM based on the measurement results of Layer 3 (L3 measurement result) or Layer 1 (L1 measurement result) (Non-Patent Document 2).

[0006] "New WID: NR mobility enhancements Phase 4", RP-234036, 3GPP TSG RAN Meeting #102, 3GPP, December 2023 3GPP R2-2407770, 3GPP RAN2#127, 3GPP, August 2024

[0007] As mentioned above, the Source DU can send a Cell Switch Command MAC-CE to the UE to perform beam-level switching. The Source DU can determine candidate cells / beams based on the L1 measurement results, but the measurement results of Layer 1 are less stable than those of Layer 3. Therefore, the candidate cells / beams selected by the Source DU may not necessarily be optimal.

[0008] Therefore, the L1 measurement result is sent to the CU, and the CU makes a comprehensive decision based on the L1 measurement result and the L3 measurement result, thereby selecting the optimal candidate cell / beam.

[0009] Once the CU has selected the best candidate cell / beam, it may send the cell switching information, including the candidate cell's synchronization signal block (SS (Synchronization Signal) / PBCH (Physical Broadcast CHannel) Block) or Channel State Information-Reference Signal (CSI-RS), directly to the UE via a Radio Resource Control (RRC) message (RRCReconfiguration message). RRC is more reliable than MAC because it also ensures security and performs retransmissions in the Radio Link Control (RLC) layer.

[0010] From the viewpoint of further improving reliability and quality, it is conceivable that the CU may utilize the Transmission Configuration Indication (TCI) state, the Timing Advance (TA) of the candidate cell, etc., but the CU is not able to utilize such parameters.

[0011] Therefore, the following disclosure has been made in consideration of this situation, and aims to provide a radio base station and a radio communication method that can more appropriately determine LTM candidate cells (beams) when a CU-DU separation configuration is applied.

[0012] One aspect of the present disclosure is a radio base station (gNB100) including a first device and one or more second devices connected to the first device, wherein the second device is a radio base station including a control unit (control unit 140) that controls the transition of a terminal to a candidate cell in accordance with mobility control by a lower layer, and a transmission unit (measurement setting unit 130) that transmits cell switching information to the first device, the cell switching information including at least one of identification information of the transmission setting instruction state of the candidate cell, an index of a beam transmitted by the second device, and a group of timing adjustment values ​​associated with the transmission setting instruction state.

[0013] FIG. 1 is a diagram showing an overall schematic configuration of a wireless communication system 10. FIG. 2 is a diagram showing an example of control by TM (L1 / L2 mobility). FIG. 3 is a functional block configuration diagram of a gNB 100. FIG. 4 is a functional block configuration diagram of a UE 200. FIG. 5 is a diagram showing an example of mapping of TCI states of an LTM candidate cell according to an operation example. FIG. 6 is a diagram showing an example of mapping of TCI UL states of an LTM candidate cell according to an operation example. FIG. 7 is a diagram showing an example of a sequence of LTM cell switching according to an operation example. FIG. 8 is a diagram showing an example of the hardware configuration of a gNB 100 and a UE 200. FIG. 9 is a diagram showing an example of the configuration of a vehicle 2001.

[0014] 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.

[0015] (1) Overall Schematic Configuration of Wireless Communication System Fig. 1 is an overall schematic configuration diagram 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).

[0016] 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).

[0017] 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, etc.) and UEs, is not limited to the example shown in FIG. 1 .

[0018] 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.

[0019] 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 the 5GC may be simply referred to as a "network." The 5GC may introduce the concept of CUPS (Control and User Plane Separation), which clearly separates the functions of the user plane and the control plane.

[0020] 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, first device) and a DU (Distributed Unit, second device), 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.

[0021] 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 aggregates and uses multiple component carriers (CCs); and Dual Connectivity (DC), which enables simultaneous communication between the UE and multiple NG-RAN nodes.

[0022] The type of DC may be Multi-RAT Dual Connectivity (MR-DC) that uses multiple radio access technologies, or NR-NR Dual Connectivity (NR-DC) that uses only NR. For example, one gNB may constitute a master node (MN), and one or more other gNBs may constitute secondary nodes (SNs).

[0023] 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.

[0024] 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).

[0025] LTM may include network-triggered LTM and UE-triggered LTM (Conditional LTM, UE-triggered LTM).

[0026] In addition, in Conditional LTM (which may also be called UE triggered LTM or 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 executes LTM if the execution condition is satisfied.

[0027] 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 RRC Reestablishment Request to the gNB 100.

[0028] 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.

[0029] 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) at the transition destination (handover destination) (UE based TA measurement). Such a TA may be referred to as a UE measured TA, for example.

[0030] 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.

[0031] 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.

[0032] Figure 2 shows an example of control by LTM (L1 / L2 mobility). As shown in Figure 2, MAC included in a lower layer (Layer 1 / Layer 2), rather than 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.

[0033] 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.

[0034] The UE 200 transmits a measurement report (hereinafter, referred to as a Measurement report) including reception qualities for cells including a serving cell and neighboring cells to the network. The procedure by which the UE 200 transmits the Measurement report may be referred to as Measurement reporting. The reception qualities for the cells may include reception qualities of beams from the cells, or may include reception qualities of cells based on beams from the cells.

[0035] The UE 200 may periodically perform measurement reporting. The UE 200 may perform measurement reporting for each event. An entering condition for starting measurement reporting and a leaving condition for terminating measurement reporting may be defined for each event. The entering condition may be interpreted as a condition for determining whether or not to include a measurement report target, and the leaving condition may be interpreted as a condition for determining whether or not to exclude a measurement report target. At least one of the entering condition and the leaving condition may be applied as an execution condition in UE triggered LTM.

[0036] In this embodiment, the channels include a control channel and a data channel, such as a physical downlink control channel (PDCCH), a physical uplink control channel (PUCCH), a physical random access channel (PRACH), and a physical broadcast channel (PBCH).

[0037] The data channels include a physical downlink shared channel (PDSCH) and a physical uplink shared channel (PUSCH).

[0038] 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.

[0039] (2) Functional Block Configuration of Wireless Communication System Next, the functional block configuration of the wireless communication system 10 will be described. Specifically, the functional block configuration 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.

[0040] (2.1) gNB100 As shown in FIG. 3, the gNB100 includes a radio communication unit 110, a handover processing unit 120, a measurement setting unit 130, and a control unit 140.

[0041] The wireless communication unit 110 transmits downlink signals (DL signals) conforming to NR, and also receives uplink signals (UL signals) conforming to NR.

[0042] 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). Note that the source cell and the target cell may also be referred to as a source radio base station (gNB) and a target radio base station (gNB).

[0043] Handover (HO) may also be called cell transition, cell selection, or cell reselection. Handover may be cell-based, but may also involve changing (switching) some of the beams to another cell.

[0044] The serving cell may be simply interpreted as the cell to which the UE 200 is connected, or more precisely, in the case of an RRC_CONNECTED UE without carrier aggregation (CA), there is only one serving cell that constitutes the primary cell. In the case of an RRC_CONNECTED UE configured with CA, the serving cell may be interpreted as indicating a set of one or more cells including the primary cell and all secondary cells.

[0045] 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 RRC Reconfiguration of the selected cell to reconnect without transmitting an RRC Reestablishment Request to the candidate target cell.

[0046] 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.

[0047] The measurement configuration unit 130 can notify the UE 200 of the contents of the measurement configuration. 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.

[0048] The measurement results may include a layer 3 measurement result (L3 measurement result) and a layer 1 measurement result (L1 measurement result).

[0049] The measurement configuration unit 130 (which may mean operation as a DU (second device)) may receive a measurement report in a lower layer from the UE 200. Specifically, the measurement configuration unit 130 may receive an L1 measurement report from the UE 200. The DU may mean a Source DU that forms a source cell of the UE 200.

[0050] Furthermore, the measurement configuration unit 130 may transmit the received measurement report (L1 measurement report) to a CU (first device). The destination CU may be a source CU (Source CU) of the UE 200. Specifically, the measurement configuration unit 130 may transmit a measurement result (L1 measurement result) included in the measurement report (L1 measurement report) to the CU.

[0051] In this case, the measurement configuration unit 130 may transmit a measurement report associated with the UE 200. Specifically, the measurement configuration unit 130 may transmit a measurement report (L1 measurement report) associated with identification information (e.g., gNB-CU UE F1AP ID) of the UE 200.

[0052] When a candidate cell to which UE200 is to be transferred is determined, the measurement setting unit 130 (here, this may mean operation as a CU (first device)) may transmit cell switching information to be used for switching to the candidate cell to the DU (Source DU).

[0053] In this case, the measurement configuration unit 130 may transmit cell switching information including at least a synchronization signal block (SS (Synchronization Signal) / PBCH (Physical Broadcast CHannel) Block)) of the candidate cell or a reference signal for channel state information estimation (CSI-RS). Note that the cell switching information may include not only the ID / index of the SSB or CSI-RS but also other parameters (described in detail later) related to the configuration of the candidate cell.

[0054] For example, a new F1-AP message (for example, LTM decision transfer message, tentative name) or an existing F1-AP message may be used, which includes cell switching information including the following items:

[0055] - Target cell / beam (SSB, CSI-RS) ID / index - Target Configuration ID - DL TCI (Transmission Configuration Indication) state ID - UL TCI state ID - Timing Advance - RACH resource (Random Access Preamble index, SS / PBCH index, PRACH Mask index) - Repetition number (indicates the Msg1 repetition number to be applied to the contention-free Random Access) - S / U indication (indicates which UL carrier (SUL (Supplementary Uplink) or NUL (Normal Uplink)) to transmit the PRACH of the contention-free Random Access Resources) Note that Msg1 may be transmitted via PRACH. Msg1 may also be referred to as PRACH Preamble.

[0056] Furthermore, the measurement configuration unit 130 (here, may mean operation as a DU (second device)) may transmit cell switching information to the CU (first device), including at least one of identification information of the transmission configuration indication (TCI) state of the candidate cell, an index of the beam transmitted by the DU, and a group of timing advances (TA) associated with the TCI state. In this embodiment, the measurement configuration unit 130 may constitute a transmitting unit. Note that the DU may mean a Source DU that forms a cell from which the UE 200 transitions.

[0057] Specifically, the measurement configuration unit 130 may transmit cell switching information including at least one of the TCI state ID, the ID / index of the SSB or CSI-RS, and the tag-Id-ptr to the CU. Note that these parameters do not necessarily need to be included in the cell switching information, and each parameter may be transmitted to the CU individually.

[0058] The tag-Id-ptr may indicate the TAG (Timing Advance Group) of the serving cell to which the TCI state applies. For example, the value n0 may mean the TCI state associated with the TAG indicated by the tag-Id (TAG identification information), and the value n1 may mean the TCI state associated with the TAG indicated by the tag2-Id.

[0059] The measurement configuration unit 130 may transmit the IDs / indexes of the SSBs and / or CSI-RSs used in the candidate cells as beam indices, i.e., the IDs / indexes of the SSBs and / or CSI-RSs may be transmitted to the CU.

[0060] Furthermore, even when transmitting cell switching information including such parameters to the CU, the measurement setting unit 130 may transmit the cell switching information associated with identification information of the UE 200 (e.g., gNB-CU UE F1AP ID).

[0061] 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 UE 200. 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).

[0062] 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.

[0063] In this embodiment, the control unit 140 (which may mean operation as a CU and a DU here) can control the transition of the UE 200 to a candidate cell in accordance with lower layer mobility management (LTM). Specifically, the control unit 140 can perform control as a CU (source side or target side) or a DU (source side or target side) in the gNB 100 having a CU-DU configuration.

[0064] The control unit 140 (which may mean operating as a DU (second device) here) may determine a candidate cell based on a measurement result (L1 measurement result) by the UE 200 in a lower layer (which may mean Layer 1 here). That is, the control unit 140 may determine a candidate cell (which may be called a target cell or a target gNB, etc.) based only on the L1 measurement result.

[0065] Alternatively, the control unit 140 (here, may mean operation as a DU (second device)) may determine a candidate cell to be a transfer destination of the UE 200 based on a measurement result of the candidate cell in a lower layer and a measurement result of the candidate cell in an upper layer. In this embodiment, the control unit 140 may constitute another control unit.

[0066] Specifically, the control unit 140 may use the L1 measurement result and the L3 measurement result to comprehensively determine the quality of the candidate cell and determine the cell to which the UE 200 should be transferred. The comprehensive determination may simply mean applying the same weight to both the L1 measurement result and the L3 measurement result, or applying a higher (or lower) weight to either of them. A lower weight may be applied to the L1 measurement result, and a higher weight may be applied to the L3 measurement result.

[0067] (2.2) UE 200 As shown in FIG. 4, the UE 200 includes a radio communication unit 210, a measurement reporting unit 220, a handover execution unit 230, and a control unit 240.

[0068] 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.

[0069] The measurement reporting unit 220 performs measurement reporting based on the configuration (measurement configuration) of quality measurements of the serving cell and neighboring cells. Specifically, the measurement reporting unit 220 may perform measurement reporting based on the measurement configuration in Layer 3, or may perform measurement reporting based on the measurement configuration in Layer 1 and / or Layer 2.

[0070] The measurement 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 measurement reporting unit 220 can perform measurement reporting of the source cell and the target cell during handover.

[0071] 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), Reference Signal Received Quality (RSRQ)).

[0072] Furthermore, the measurement reporting unit 220 may transmit, to the network, capability information (UE Capability Information) indicating capabilities related to cell switching information used for switching to a candidate cell. Specifically, the measurement reporting unit 220 may transmit UE Capability Information including support status of a UE capability indicating support status of receiving the cell switching information from the CU via an RRCReconfiguration message.

[0073] 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.

[0074] The handover execution unit 230 can also execute processes related to normal handover (legacy handover), handover according to LTM (L1 / L2 Mobility), conditional handover (CHO), and DAPS handover. The handover execution unit 230 can also support RACH less HO (RACH less LTM).

[0075] In addition, in order to perform RACH less HO, the handover execution unit 230 may execute a method (early TA acquisition) in which the target cell (which may also be called a target gNB, candidate cell, etc.) acquires a TA for its own cell in advance.

[0076] The handover execution unit 230 may transition to the candidate cell when an execution condition is satisfied. The execution condition may be determined based on the quality of the reference signal (RS), specifically, the value of the reference signal received power (RSRP), the reference signal received quality (RSRQ), or the signal-to-interference plus noise power ratio (SINR).

[0077] As described above, handover may be interpreted as transition, cell transition, cell selection, etc. Specifically, the handover execution unit 230 may execute handover based on LTM based on at least one command of layer 1 and / or layer 2.

[0078] The type of the command is not particularly limited, and may be, for example, an L1 / L2 Mobility command (e.g., Cell Switch Command MAC-CE). The L1 / L2 Mobility command may be replaced with another command of the RRC layer.

[0079] 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.

[0080] The control unit 240 can also perform L1 / L2 Mobility (LTM), i.e., 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 perform handover in accordance with mobility control by a lower layer.

[0081] (3) Operation of the Wireless Communication System Next, we will explain the operation of the wireless communication system 10. Specifically, we will explain the operation related to inter-CU LTM (Inter-CU LTM) or intra-CU LTM (Intra-CU LTM) by the gNB 100 with a CU-DU separated configuration.

[0082] (3.1) Assumptions and Issues The UE transmits a Layer 1 measurement report (L1 measurement report) to the Source DU, and the Source DU selects a cell (or beam) with good quality included in the L1 measurement report to determine the candidate cell (beam) for LTM. The Source DU instructs the UE on the candidate cell (beam) using a Cell Switch Command (MAC-CE). In the following description, the term "candidate cell" may be interpreted as including the candidate beam.

[0083] In 3GPP, it is being considered that the Source CU will determine candidate cells (beams) for LTM based on the layer 3 measurement result (L3 measurement result) or the layer 1 measurement result (L1 measurement result).

[0084] In the case of CU-DU separation configuration, the Source DU can send a Cell Switch Command MAC-CE to the UE to perform beam-level switching. The Source DU can determine candidate cells / beams based on the L1 measurement results, but the measurement results of Layer 1 are less stable than those of Layer 3. Therefore, the candidate cells / beams selected by the Source DU may not necessarily be optimal.

[0085] Therefore, the L1 measurement result is sent to the CU, and the CU makes a comprehensive decision based on the L1 measurement result and the L3 measurement result, thereby selecting the optimal candidate cell / beam.

[0086] Once the CU has selected the best candidate cell / beam, it may send the cell switching information, including the candidate cell's SSB or CSI-RS, directly to the UE via an RRCReconfiguration message. RRC is more reliable than MAC because it also ensures security and performs retransmissions in the Radio Link Control layer (RLC).

[0087] From the viewpoint of further improving reliability, it is conceivable that the CU utilizes the TCI state, TA, etc., but the CU cannot utilize such parameters because the TCI state is generated and managed by the Source DU. Also, the DU-CU TA INFORMATION TRANSFER message specified in 3GPP TS38.473 is a non-UE associated message, and the CU does not recognize the TA.

[0088] (3.2) Operation Example Figure 5 shows an example of mapping of the TCI state of an LTM candidate cell according to the operation example. Figure 6 shows an example of mapping of the TCI UL state of an LTM candidate cell according to the operation example. Figure 7 shows an example of the sequence of LTM cell switching according to the operation example.

[0089] (3.2.1) DL / UL TCI state ID As shown in Figures 5 to 7, the Source DU may send mapping information of the DL / UL TCI state ID, beam (SSB or CSI-RS) index, and tag-Id-ptr of each candidate cell to the CU via an F1-AP message.

[0090] The Source DU may select one or more candidate cells with good L1 quality from among all candidate cells based on the L1 measurement result, and transmit mapping information between the DL / UL TCI state IDs and beam (SSB or CSI-RS) indices of the selected candidate cells to the CU. For example, the Source DU may transmit mapping information between the DL / UL TCI state IDs and beam (SSB or CSI-RS) indices of the top three candidate cells with good quality among eight candidate cells to the CU.

[0091] Mapping information between the DL / UL TCI state ID and beam (SSB or CSI-RS) index of each candidate cell may be associated with the UE ID and transmitted from the Source DU to the CU after the UE.

[0092] The CU may perform a comprehensive judgment based on the L1 measurement result and the L3 measurement result, determine the index of the optimal candidate cell (target cell), and determine the TCI-State-ID and TCI-UL-state-ID using the above-mentioned mapping information based on the cell ID and beam index of the determined cell.

[0093] (3.2.2) Timing Advance The Source DU may transmit the TA value and tag-Id-ptr of each candidate cell to the CU by an F1-AP message. The TA value and tag-Id-ptr may be transmitted from the Source DU to the CU in association with a UE ID (e.g., NB-CU UE F1AP ID, gNB-DU UE F1AP ID) and a cell ID (e.g., LTM candidate ID).

[0094] The TA value may be included in the TA value transferred from the Target DU (DU-CU TA INFORMATION TRANSFER, see 3GPP TS38.473).

[0095] The CU may send an RRCReconfiguration message to the UE including at least one of the determined target cell ID (LTM candidate ID), beam (SSB or CSI-RS) index, TCI-State-ID, TCI-UL-state-ID, and TA value.

[0096] According to the above-described operation example, information on the DL / UL TCI state ID, beam (SSB or CSI-RS) index, and tag-Id-ptr of each candidate cell is transmitted from the Source DU to the CU. Therefore, the CU can use parameters such as the UE's TCI state, the candidate cell's TA value, and the TAG of the serving cell to which the TCI state indicated by the tag-Id-ptr is applied, to select a candidate cell (target cell).

[0097] This allows the gNB to more appropriately determine LTM candidate cells (beams) when a CU-DU separation configuration is applied.

[0098] (4) Other Embodiments The contents of the present proposal have been described above in accordance with the examples, but it will be obvious to those skilled in the art that the present proposal is not limited to these descriptions and that various modifications and improvements are possible.

[0099] For example, 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.

[0100] Furthermore, specific, dedicated, UE-specific, and UE-dedicated may be interchangeable. Similarly, common, shared, group-common, UE-common, and UE-shared may be interchangeable.

[0101] In this disclosure, terms such as "precoding," "precoder," "weight (precoding weight)," "Quasi-Co-Location (QCL)," "Transmission Configuration Indication state (TCI state)," "spatial relation," "spatial domain filter," "transmit power," "phase rotation," "antenna port," "antenna port group," "layer," "number of layers," "rank," "resource," "resource set," "resource group," "beam," "beam width," "beam angle," "antenna," "antenna element," "panel," etc. may be used interchangeably.

[0102] Furthermore, the block diagrams (FIGS. 3 and 4) used to explain the above-described embodiments show functional blocks. These functional blocks (components) are realized by any combination of hardware and / or software. Furthermore, the method for 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 (e.g., wired, wireless, etc.) and these multiple devices. The functional block may also be realized by combining software with the single device or multiple devices.

[0103] Functions include, but are not limited to, judgment, determination, judgment, calculation, computation, processing, derivation, investigation, search, confirmation, reception, transmission, output, access, resolution, selection, selection, 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.

[0104] Furthermore, the above-described gNB100 and UE200 (the devices) 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 devices. As shown in Figure 8, the devices 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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, and registers.

[0109] 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-described embodiments. Furthermore, the various processes described above may be executed by a single 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.

[0110] The memory 1002 is a computer-readable recording medium and may be configured by at least one of, for example, 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 may store a program (program code), a software module, etc., capable of executing a method according to an embodiment of the present disclosure.

[0111] 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 suitable medium including at least one of memory 1002 and storage 1003.

[0112] 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.

[0113] 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).

[0114] The input device 1005 is an input device (e.g., 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 (e.g., a display, a speaker, an LED lamp, etc.) that outputs to the outside. Note that the input device 1005 and the output device 1006 may be integrated into one device (e.g., a touch panel).

[0115] 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.

[0116] 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.

[0117] 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.

[0118] 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 system, and a next-generation system extended based on these. Furthermore, a combination of multiple systems (e.g., a combination of at least one of LTE and LTE-A with 5G) may also be applied.

[0119] 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.

[0120] 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 (e.g., MME or 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 (e.g., MME and S-GW) may also be used.

[0121] 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 and output via multiple network nodes.

[0122] The input and output information may be stored in a specific location (for example, a memory) or may be managed using a management table. The input and output information may be overwritten, updated, or added. The output information may be deleted. The input information may be transmitted to another device.

[0123] 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).

[0124] The aspects / embodiments described in this disclosure may be used alone, in combination, or switched depending on the implementation. Notification of predetermined information (e.g., notification that "X is true") is not limited to explicit notification, but may be implicit (e.g., not notifying the predetermined information).

[0125] 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.

[0126] 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.

[0127] 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.

[0128] Note that terms described 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.

[0129] As used in this disclosure, the terms "system" and "network" are used interchangeably.

[0130] 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.

[0131] 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.

[0132] 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.

[0133] 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)).

[0134] 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.

[0135] 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.

[0136] In this disclosure, the terms "Mobile Station (MS)," "user terminal," "User Equipment (UE)," "terminal," etc. may be used interchangeably.

[0137] 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.

[0138] At least one of the base station and the mobile station may be referred to as 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, the mobile object itself, etc. The mobile object refers to a movable object, and may move at any speed. Naturally, this also includes cases where the mobile object is stationary. Examples of the mobile object include, but are not limited to, vehicles, transport vehicles, automobiles, motorcycles, bicycles, connected cars, excavators, bulldozers, wheel loaders, dump trucks, forklifts, trains, buses, handcars, rickshaws, ships and other watercraft, airplanes, rockets, satellites, drones (registered trademark), multicopters, quadcopters, balloons, and objects mounted thereon. The mobile object may also be a mobile object that moves autonomously based on an operational command. It 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 be a device that does not necessarily move during communication operations. For example, at least one of the base station and the mobile station may be an IoT (Internet of Things) device such as a sensor.

[0139] Furthermore, a base station in the present disclosure may be read 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 read as terms corresponding to terminal-to-terminal communication (for example, "side"). For example, terms such as an uplink channel and a downlink channel may be read as a side channel (or sidelink).

[0140] 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.

[0141] 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.

[0142] Numerology may be communication parameters that apply to the transmission and / or 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 the transceiver in the frequency domain, and specific windowing operations performed by the transceiver in the time domain.

[0143] 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.

[0144] 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.

[0145] 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.

[0146] For example, one subframe may be referred to as a transmission time interval (TTI), multiple consecutive subframes may be referred to as a TTI, or one slot or one minislot may be referred to as 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.

[0147] Here, TTI refers to, for example, the smallest time unit for scheduling in wireless communication. For example, in an LTE system, a base station schedules each user terminal to allocate radio resources (such as frequency bandwidth and transmission power that can be used by each user terminal) in TTI units. Note that the definition of TTI is not limited to this.

[0148] 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.

[0149] In addition, 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, and the number of slots (minislots) constituting the minimum time unit for scheduling may be controlled.

[0150] A TTI having a time length of 1 ms may be referred to as 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 referred to as a shortened TTI, short TTI, partial or fractional TTI, shortened subframe, short subframe, minislot, subslot, slot, etc.

[0151] 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.

[0152] A resource block (RB) is a resource allocation unit in the time domain and the 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 be determined based on numerology.

[0153] The time domain of an RB may include one or more symbols and may have a length of one slot, one minislot, one subframe, or one TTI, each of which may consist of one or more resource blocks.

[0154] 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, etc.

[0155] 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.

[0156] 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.

[0157] 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.

[0158] 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."

[0159] 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 may be changed in various ways.

[0160] 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.

[0161] The reference signal may also be abbreviated as Reference Signal (RS) and may be called a pilot depending on the applicable standard.

[0162] 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."

[0163] The "means" in the configuration of each of the above devices may be replaced with "part," "circuit," "device," etc.

[0164] 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.

[0165] When the terms "include," "including," and variations thereof are used in this disclosure, these terms are intended to be inclusive, similar to the term "comprising." Furthermore, when the term "or" is used in this disclosure, it is not intended to be an exclusive or.

[0166] 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.

[0167] 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.

[0168] 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."

[0169] 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.

[0170] 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, memory (ROM, RAM) 2032, and a communication port (IO port) 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).

[0171] 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.

[0172] 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 uses information acquired from external devices via the communication module 2013, etc., to provide various types of multimedia information and multimedia services to the occupants of the vehicle 1.

[0173] 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.

[0174] 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.

[0175] 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 driving 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.

[0176] 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.

[0177] The communication module 2013 may transmit at least one of signals from the above-mentioned various sensors 2021 to 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 to 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.

[0178] 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 also 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 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 to 2028, and the like provided in the vehicle 2001.

[0179] (Additional Note) The above disclosure may be expressed as follows: A first feature is a radio base station including a first device and one or more second devices connected to the first device, wherein the second device includes: a control unit that controls a terminal's transition to a candidate cell in accordance with mobility control by a lower layer; and a transmission unit that transmits, to the first device, cell switching information including at least any one of identification information of a transmission setting instruction state of the candidate cell, an index of a beam transmitted by the second device, and a group of timing adjustment values ​​associated with the transmission setting instruction state.

[0180] In a second feature based on the first feature, the transmitter transmits an index of a synchronization signal block or a reference signal for estimating channel state information of the candidate cell as an index of the beam.

[0181] A third feature based on the first or second feature is that the control unit determines the candidate cell based on a measurement result by the terminal in the lower layer.

[0182] A fourth feature, in any one of the first to third features, is that the transmitter transmits the cell switching information associated with the terminal.

[0183] A fifth feature is that, in any of the first to fourth features, the second device includes another control unit that determines a candidate cell to which the terminal is to be transferred, based on measurement results of the candidate cell in the lower layer and measurement results of the candidate cell in the upper layer.

[0184] This patent application claims priority based on Japanese Patent Application No. 2024-143172, filed on August 23, 2024, the entire contents of which are incorporated herein by reference.

[0185] 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 Measurement 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 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 system section 2031 Microprocessor 2032 Memory (ROM, RAM) 2033 Communication port

Claims

1. A radio base station including a first device and one or more second devices connected to the first device, wherein the second device includes: a control unit that controls a terminal's transition to a candidate cell in accordance with mobility control by a lower layer; and a transmission unit that transmits cell switching information to the first device, the cell switching information including at least one of identification information of the transmission setting instruction state of the candidate cell, an index of a beam transmitted by the second device, and a group of timing adjustment values ​​associated with the transmission setting instruction state.

2. The radio base station according to claim 1, wherein the transmitter transmits an index of a synchronization signal block or a reference signal for estimating channel state information of the candidate cell as an index of the beam.

3. The radio base station according to claim 1, wherein the control unit determines the candidate cells based on measurement results by the terminal in the lower layer.

4. The radio base station according to claim 1, wherein the transmitting unit transmits the cell switching information associated with the terminal.

5. The radio base station according to claim 1, wherein the second device comprises another control unit that determines a candidate cell to which the terminal is to transition based on the measurement results of the candidate cell in the lower layer and the measurement results of the candidate cell in the upper layer.

6. A wireless communication method using a wireless base station including a first device and one or more second devices connected to the first device, comprising: a step in which the second device controls the transition of a terminal to a candidate cell in accordance with mobility control by a lower layer; and a step in which the second device transmits cell switching information to the first device, the cell switching information including at least one of identification information of the transmission setting instruction state of the candidate cell, an index of a beam transmitted by the second device, and a group of timing adjustment values ​​associated with the transmission setting instruction state.

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