Wireless base station and wireless communication method

Abstract

To provide a wireless base station and a wireless communication method that can realize appropriate UE transition according to the setting state of lower layers between RAN nodes related to the UE transition, even when Inter-CU LTM is executed.SOLUTION: A wireless base station performs mobility control in the lower layer and transmits cell information indicating cells using the same settings in the lower layer to other wireless base stations.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present disclosure relates to a radio base station and a radio communication method that support LTM (L1 / L2 mobility). [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 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] 3GPP Release-18 specifies the transition (Intra-CU LTM) between Distributed Units (DUs) connected to the same Central Unit (CU), and the UE can determine whether to reset (or re-establish) lower layers such as the Radio Link Control layer (RLC) and Packet Data Convergence Protocol layer (PDCP) based on identification information called ltm-NoResetID, which is assigned to each LTM candidate cell. Specifically, the UE may determine that reset of lower layers is not necessary if ltm-NoResetID is the same as the value of identification information (ltm-ServingCellNoResetID) related to whether to reset the serving cell included in the LTM configuration information (LTM-Config-r18).

[0005] 3GPP Release-19 enables LTM between CUs (Inter-CU LTM), but it proposes a transition that changes only the control plane (CP) and maintains the user plane (UP), i.e., does not require a PDCP setting change (called a PDCP anchor change) (Non-Patent Document 2).

[0006] Also, in 3GPP Release-19, it has been agreed to introduce ltm-NoResetID to determine whether or not a lower layer needs to be reset (Non-Patent Document 3). [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] "New WID: NR mobility enhancements Phase 4", RP-234036, 3GPP TSG RAN Meeting #102, 3GPP, December 2023 [Non-patent document 2] "Inter-gNB LTM and keep PDCP anchor", R3-243522, 3GPP TSG-RAN WG3 #124, 3GPP, May 2024 [Non-patent document 3] "Report of 3GPP TSG RAN WG2 meeting #127", R2-2409210, 3GPP TSG-RAN WG2 meeting #127bis, 3GPP, October 2024 Summary of the Invention [Problem to be solved by the invention]

[0008] In the case of Inter-CU LTM in 3GPP Release-19, since a UE transitions between different CUs (which may be interpreted as radio base stations (gNBs)), it is necessary for RAN (Radio Access Network) nodes, such as gNBs, that may be involved in the transition to recognize whether the serving cell and candidate cell use the same PDCP configuration (which may also be called a PDCP anchor, PDCP entity, or PDCP termination point).

[0009] In particular, when Inter-CU LTM without PDCP anchor change is introduced, PDCP setting changes may not be required even in the case of UE transition (handover) across gNBs (CUs). However, RAN nodes such as gNBs that may be involved in the transition cannot recognize the configuration status of lower layers, including PDCP. For this reason, they may not be able to properly support Inter-CU LTM without PDCP anchor change.

[0010] Therefore, the following disclosure has been made in consideration of such circumstances, and aims to provide a radio base station and a radio communication method that can realize appropriate UE transition in accordance with the configuration state of lower layers between RAN nodes related to the UE transition, even when Inter-CU LTM is executed. [Means for solving the problem]

[0011] One aspect of the present disclosure is a radio base station (gNB100) that includes a control unit (control unit 140) that performs mobility control in a lower layer, and a transmission unit (handover processing unit 120) that transmits cell information indicating cells that use the same settings in the lower layer to other radio base stations.

[0012] One aspect of the present disclosure is a radio base station (gNB100) comprising a control unit (control unit 140) that performs mobility control in a lower layer, and a transmission unit (handover processing unit 120) that transmits a handover-related message including cell information indicating cells using the same or different settings in the lower layer to another radio base station or another network device.

[0013] 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 first device includes a control unit (control unit 140) that performs mobility control in a lower layer, and a transmission unit (handover processing unit 120) that transmits cell information indicating the cell to the second device, for which the first device and the second device use the same settings in the lower layer.

[0014] 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 first device includes a control unit (control unit 140) that performs mobility control in a lower layer, and a transmission unit (handover processing unit 120) that transmits cell information to the second device indicating a cell that uses the same configuration in the lower layer as a serving cell or a configuration in the lower layer that is different from the serving cell. [Brief explanation of the drawings]

[0015] [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 showing an example of control by LTM (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 in which PDCP anchor change is not required in Inter-CU LTM. [Figure 6] FIG. 6 is a diagram showing an example in which a PDCP anchor change is required in Inter-CU LTM. [Figure 7] FIG. 7 is a diagram illustrating an example of a cell information exchange sequence between RAN nodes. [Figure 8] Figure 8 shows example 1 of the cell information exchange sequence between the source gNB and the target gNB. [Figure 9] Figure 9 shows example 2 of the cell information exchange sequence between the source gNB and the target gNB. [Figure 10] FIG. 10 is a diagram showing an example of a cell information exchange sequence between a CU and a DU. [Figure 11] FIG. 11 is a diagram showing an example of the hardware configuration of gNB100 and UE200. [Figure 12]FIG. 12 is a diagram showing an example of the configuration of a vehicle 2001. DETAILED DESCRIPTION OF THE INVENTION

[0016] 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.

[0017] (1) Overall configuration of the 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).

[0018] 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).

[0019] 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 .

[0020] 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.

[0021] 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.

[0022] The NG-RAN 20 is connected to an Access and Mobility Management Function (AMF), which is included in the 5G system architecture and provides a function for managing access and mobility of the UE 200, a Session Management Function (SMF), which provides a function for managing sessions, etc. Furthermore, a UDM / UDR (Unified Data Management / User Data Repository) may be connected to the AMF and / or SMF.

[0023] 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 (CU-DU split). 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 (F1-AP, etc.). In this embodiment, the CU may be called a communication device or a central device, etc. The DU may be called a distributed device, etc.

[0024] 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.

[0025] 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).

[0026] The wireless communication system 10 may also support a conditional handover (CHO). The CHO can execute a handover initiated by the UE 200 when a specific execution condition is met. If the CHO is not applicable, a normal handover (which may be called a CHO recovery) may be executed. Furthermore, the wireless communication system 10 may support conditional addition or change (CPAC) of a Primary SCell (PSCell). A PSCell is a type of secondary cell. A PSCell means a Primary SCell (secondary cell), and may be interpreted as corresponding to any one of a plurality of SCells.

[0027] 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.

[0028] 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).

[0029] LTM may include network-triggered LTM and UE-triggered LTM (Conditional LTM, UE-triggered LTM).

[0030] 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.

[0031] When the gNB100 adopts a CU-DU configuration (CU-DU split), LTM between DUs connected to the same CU (Intra-CU LTM) and LTM between CUs (Inter-CU LTM) may be supported. Intra-CU LTM is supported in 3GPP Release-18 (which may also be referred to as the first release, an older release, etc.), and Inter-CU LTM may be supported in 3GPP Release-19 (which may also be referred to as the second release, a new release, etc.).

[0032] In the Inter-CU LTM, a transition that changes only the control plane (CP) and maintains the user plane (UP), that is, an Inter-CU LTM without PDCP anchor change that does not require a PDCP setting change (PDCP anchor change), may be applied. Note that not only PDCP but also RLC may be targeted.

[0033] LTM may include LTM fast failure recovery. LTM fast failure recovery is a mechanism in which, in the event of an LTM failure, UE 200 performs cell selection, and if the selected cell is an LTM candidate cell, UE 200 directly applies the configuration of the candidate cell without transmitting an RRC Reestablishment Request to gNB 100.

[0034] 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.

[0035] Figure 2 shows an example of control by LTM (L1 / L2 mobility). As shown in Figure 2, MAC included in the 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 a candidate), and timer management for determining whether HO is successful. Note that the lower layer may include RLC and PDCP.

[0036] The MAC may report information related to the measurement report, the HO decision, and the timer to a higher layer (RRC). The RRC may manage the state of radio resources associated with the cell transition of the UE 200 based on the report.

[0037] The UE 200 may periodically perform measurement reporting. Measurement reporting may be realized by measurement in a higher layer (which may be called Layer 3) (L3 Measurement) or by measurement in a lower layer (which may be called Layer 1) (L1 Measurement).

[0038] Furthermore, UE 200 may execute measurement reporting for each event (this may be called event-triggered measurement reporting). An entering condition for starting measurement reporting and a leaving condition for terminating measurement reporting may be defined for each event. Existing events may include the following events (see 3GPP TS38.331). Note that 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.

[0039] (i)Event A1 (Serving becomes better than threshold) Event A1 is an event in which the reception quality of the serving cell becomes better than a threshold. For example, the entering condition is Ms - Hys > Thresh, and the leaving condition is Ms + Hys < Thresh.

[0040] Here, Ms is the reception quality of the serving cell, Hys is a hysteresis parameter, and Thresh is a threshold value.

[0041] (ii)Event A2 (Serving becomes worse than threshold) Event A2 is an event in which the reception quality of the serving cell becomes worse than a threshold. For example, the entering condition is Ms + Hys < Thresh, and the leaving condition is Ms - Hys > Thresh.

[0042] Here, Ms is the reception quality of the serving cell, Hys is a hysteresis parameter, and Thresh is a threshold value.

[0043] (iii)Event A3 (Neighbor becomes offset better than SpCell) Event A3 is an event in which the reception quality of the neighboring cell is better than the reception quality of the serving cell by an offset. For example, the entering condition is Mn + Ofn + Ocn - Hys > Mp + Ofp + Ocp + Off, and the leaving condition is Mn + Ofn + Ocn + Hys < Mp + Ofp + Ocp + Off.

[0044] where Mn is the reception quality of the neighboring cell, Ofn is the offset specific to the measurement object, and Ocn is the offset specific to the cell. Mp is the reception quality of the serving cell, Ofp is the offset specific to the measurement object, and Ocp is the offset specific to the cell. Hys is the hysteresis parameter, and Off is the parameter used in Event A3.

[0045] (iv)Event A4 (Neighbor becomes better than threshold) Event A4 is an event in which the reception quality of a neighboring cell becomes better than a threshold. For example, the entering condition is Mn + Ofn + Ocn - Hys > Thresh, and the leaving condition is Mn + Ofn + Ocn + Hys < Thresh.

[0046] where Mn is the reception quality of the neighboring cell, Ofn is an offset specific to the measurement object, Ocn is an offset specific to the cell, Hys is a hysteresis parameter, and Thresh is a threshold value.

[0047] (v)Event A5 (SpCell becomes worse than threshold1 and neighbor becomes better than threshold2) Event A5 is an event in which the reception quality of the serving cell becomes worse than a threshold and the reception quality of the neighboring cell becomes better than a threshold. For example, the entering condition is Mp + Hys < Thresh1 and Mn + Ofn + Ocn - Hys > Thresh2, and the leaving condition is Mp - Hys > Thresh1 and Mn + Ofn + Ocn + Hys < Thresh2.

[0048] where Ms is the receiving quality of the serving cell, Hys is a hysteresis parameter, Thresh1 is a threshold, Mn is the receiving quality of the neighboring cell, Ofn is a measurement object-specific offset, and Ocn is a cell-specific offset, Hys is a hysteresis parameter, and Thresh2 is a threshold.

[0049] (vi)Event A6 (Neighbor becomes offset better than SCell) Event A6 is an event in which the reception quality of a neighboring cell becomes better than the reception quality of a SCell (Secondary Cell) by an offset. For example, the entering condition is Mn + Ocn - Hys > Ms + Ocs + Off, and the leaving condition is Mn + Ocn + Hys < Ms + Ocs + Off.

[0050] In addition to the events described above, events related to RATs (Radio Access technologies) (e.g., B1 (Inter RAT neighbor becomes better than threshold), B2 (Serving becomes worse than threshold1 and inter RAT neighbor becomes better than threshold2)) may be included.

[0051] Here, Mn is the reception quality of the neighboring cell, Ocn is a cell-specific offset, Ms is the reception quality of the SCell, Ocs is a cell-specific offset, Hys is a hysteresis parameter, and Off is a parameter used in Event A6.

[0052] In this embodiment, an event dedicated to the LTM may be defined. For example, the following event dedicated to the LTM may be defined.

[0053] 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 Note that the events dedicated to LTM are not limited to the above-mentioned Event LTM2 to Event LTM5, and for example, events related to the beam of the serving cell or candidate cell may be added.

[0054] 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).

[0055] The data channels include a PDSCH (Physical Downlink Shared Channel) and a PUSCH (Physical Uplink Shared Channel).

[0056] 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.

[0057] (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.

[0058] (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.

[0059] The wireless communication unit 110 transmits downlink signals (DL signals) conforming to NR, and also receives uplink signals (UL signals) conforming to NR.

[0060] The handover processing unit 120 executes handover of the UE 200. Specifically, the handover processing unit 120 executes handover of the UE 200 from a serving cell to another nearby cell.

[0061] In particular, in this embodiment, the handover processing unit 120 can handle mobility control by a lower layer of the UE 200, specifically, handover (cell transition) according to LTM.

[0062] 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.

[0063] 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 RRC Reestablishment Request to the candidate target cell.

[0064] The execution condition may consist of one or two trigger conditions (e.g., 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.

[0065] Furthermore, the handover processing unit 120 may transmit cell information regarding the cell formed by the gNB 100 (which may include neighboring cells formed by other radio base stations) to other radio base stations (gNBs). In this embodiment, the handover processing unit 120 may constitute a transmitting unit that transmits the cell information. Note that neighboring cells may also be called adjacent cells, surrounding cells, etc., and some (or all) of the area of ​​a cell may overlap with the area of ​​another cell. Furthermore, neighboring cells are not limited to cells that are spatially adjacent, but may also be cells that are frequency- or logically adjacent or overlapping.

[0066] In this embodiment, the handover processing unit 120 may transmit cell information indicating cells using the same settings in a lower layer to other radio base stations. Here, the lower layer may mean at least one of RLC and PDCP. However, MAC is not excluded. The same settings may mean that some settings in RLC or PDCP are the same, and may particularly mean the PDCP anchor. The PDCP anchor may be interpreted as the PDCP settings (including security keys) themselves or the location where the PDCP is set, and may be called a PDCP entity or a PDCP termination point, for example. The cell information may be provided in the form of a cell list, but is not necessarily limited to the list format.

[0067] The handover processing unit 120 may transmit a handover-related message including the cell information to another radio base station or another network device. Specifically, the handover processing unit 120 may transmit (or receive) a Handover request or a Handover request ACK to another gNB. However, the handover-related messages are not limited to these, and other messages such as Handover Required may also be used. Furthermore, the other network device may be broadly interpreted as a RAN node or a node constituting a core network, but may also be narrowly interpreted as an AMF, an SMF, or the like.

[0068] The handover processing unit 120 (when configuring a CU) may transmit cell information indicating cells for which the CU (first device) and DU (second device) use the same settings in lower layers to the DU. As described above, the same settings in lower layers may mean that some settings in RLC or PDCP are the same. Specifically, a list of cells using the same PDCP anchor may be transmitted from the CU to the DU.

[0069] Furthermore, the handover processing unit 120 (when a CU is configured) may transmit to the DU cell information indicating cells that use the same settings in a lower layer as the serving cell. The handover processing unit 120 (when a CU is configured) may transmit to the DU cell information indicating cells that use settings in a lower layer different from that of the serving cell. Specifically, a list of cells that use the same PDCP anchor as the serving cell may be transmitted from the CU to the DU.

[0070] 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 a lower layer (layer 1 and / or layer 2).

[0071] Note that measurement in a lower layer may mean measurement of Layer 1 (which may include MAC) including PHY, but may also include processing related to measurement in RLC and PDCP. Control information in a lower layer is typically a control element (MAC CE) of the medium access control layer, but may also be downlink control information (DCI).

[0072] 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.

[0073] The control unit 140 controls each functional block constituting the gNB 100. In particular, in this embodiment, the control unit 140 can execute measurement reports by the UE 200 and mobility control with the UE 200. Specifically, the control unit 140 can execute not only mobility control according to L3 mobility but also mobility control according to a lower layer, specifically LTM (L1 / L2 mobility).

[0074] 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.

[0075] 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.

[0076] (2.2)UE200 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.

[0077] 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.

[0078] The measurement reporting unit 220 can measure the quality of the serving cell of the UE 200 and neighbor cells of the serving cell and report a measurement report indicating the measurement result to the network. The measurement reporting unit 220 can perform measurement reporting of the source cell and the target cell during handover. The measurement reporting unit 220 can transmit a measurement report including the quality of the serving cell and neighbor cells.

[0079] 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)).

[0080] Furthermore, the measurement reporting unit 220 may support events (eg, Event LTM2, Event LTM3, etc.) used to trigger a measurement report according to lower layer mobility management (LTM).

[0081] The measurement reporting unit 220 may transmit the above-mentioned Measurement Report using a control element (MAC CE) of the Medium Access Control layer or a PUCCH (uplink control channel). Note that the uplink control channel used to transmit the Measurement Report is not necessarily limited to the PUCCH, and may be any other channel as long as it is a channel for control information.

[0082] 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.

[0083] In addition, the handover execution unit 230 can execute processes related to normal handover (legacy handover), conditional handover (CHO), and DAPS handover.

[0084] 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.

[0085] 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.

[0086] Furthermore, the handover execution unit 230 may execute handover based on not only L3 Mobility but also LTM (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 LTM based on at least one command of layer 1 and / or layer 2.

[0087] 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 in the RRC layer or a control element (CE) in the MAC layer. The handover executing unit 230 may receive setting information related to L1 / L2 Mobility (LTM). The setting information may mean settings related to LTM (LTM-config). However, the setting information does not necessarily have to be LTM-config as long as it indicates settings related to LTM (which may include execution conditions, etc.).

[0088] The handover execution unit 230 may execute a transition (which may be read as handover (HO), cell (beam) selection, cell (beam) reselection, etc.) of the UE 200 in accordance with mobility management (LTM) in a lower layer. Specifically, the handover execution unit 230 may support Intra-CU LTM and Inter-CU LTM.

[0089] More specifically, the handover executing unit 230 may determine whether or not it is necessary to reset lower layers such as RLC and PDCP, based on identification information called ltm-NoResetID that is assigned to each LTM candidate cell.

[0090] ltm-NoResetID may be associated with a 3GPP release. Specifically, ltm-NoResetID-r18 may be set for 3GPP Release-18, and ltm-NoResetID-r19 (may be a tentative name) may be set for 3GPP Release-19.

[0091] The handover executing unit 230 may determine that reset of the lower layer is not required when the ltm-NoResetID (ltm-NoResetID-r18, ltm-NoResetID-r19) is the same as the value of identification information (ltm-ServingCellNoResetID) related to the necessity of resetting the serving cell included in the LTM configuration information (LTM-Config-r18). Note that the ltm-NoResetID may be represented by, for example, any integer.

[0092] The handover execution unit 230 may receive candidate cell information in the LTM in which at least one of ltm-NoResetID-r18 (first identification information) and ltm-NoResetID-r19 (second identification information) regarding whether or not the lower layer needs to be reset is set.

[0093] The candidate cell information indicates information on a cell (or beam) to which the UE 200 is to transition by LTM, and may be called, for example, LTM-Candidate-r19 (a tentative name). The LTM-Candidate-r19 may include identification information of the candidate cell, information on PCI (Physical Cell ID) and SSB (SS (Synchronization Signal) / PBCH (Physical Broadcast CHannel) Block), etc.

[0094] Furthermore, a reset of a lower layer may be interpreted as a reset in at least one of the MAC, PDCP, and RLC layers. Such a reset may be called an L2 Reset. Reset may also be interpreted as resetting, re-establishing, initializing, restarting, re-establishing, or updating.

[0095] Furthermore, the handover executor 230 may transmit capability information (UE capability information) related to LTM to the network. For example, the handover executor 230 may report to the network whether or not the ltm-NoResetID for each 3GPP release is supported.

[0096] The control unit 240 controls each functional block constituting the UE 200. Specifically, 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 control handover in accordance with mobility control by a lower layer.

[0097] Furthermore, the control unit 240 may determine whether or not a lower layer reset (L2 Reset) is necessary based on ltm-NoResetID-r18 (first identification information) or ltm-NoResetID-r19 (second identification information). As described above, ltm-NoResetID may be included in candidate cell information of a transfer destination by LTM (LTM-Candidate-r19, which may be a tentative name). However, it does not necessarily have to be LTM-Candidate-r19, and ltm-NoResetID may be included in an RRC information element (IE) indicating a candidate cell (which may be a beam) of a transfer destination of the UE 200.

[0098] When only ltm-NoResetID-r18 is set in the candidate cell information and the value of ltm-NoResetID-r18 is the same as the value of reset identification information (ltm-ServingCellNoResetID) related to the reset of the serving cell, the control unit 240 may determine that the reset (L2 Reset) is unnecessary. In other words, when the values ​​do not match, the control unit 240 may determine that an L2 Reset is necessary.

[0099] When ltm-NoResetID-r18 and ltm-NoResetID-r19 are set in the candidate cell information, the control unit 240 may determine whether an L2 reset is necessary depending on whether ltm-NoResetID-r18 and ltm-NoResetID-r19 are the same as the value of ltm-ServingCellNoResetID (reset identification information). Specifically, when the value of ltm-NoResetID-r19 is the same as the value of ltm-ServingCellNoResetID, the control unit 240 may determine that a PDCP anchor change is unnecessary between the source cell at the transition source and the candidate cell at the transition destination. On the other hand, when the value of ltm-NoResetID-r19 is different from the value of ltm-ServingCellNoResetID, the control unit 240 may determine that a PDCP anchor change is necessary between the source cell at the transition source and the candidate cell at the transition destination.

[0100] The PDCP anchor change may be interpreted as a change of a security key used by the UE 200 for connecting to the network. When the ltm-NoResetID-r19 is not set in the candidate cell information, that is, when the candidate cell information does not include the ltm-NoResetID-r19, the control unit 240 may determine that a PDCP anchor change, in other words, a PDCP setting change including a security key change, is not necessary.

[0101] Furthermore, when only ltm-NoResetID-r19 is set in the candidate cell information, control unit 240 may determine whether a PDCP anchor change is necessary depending on whether ltm-NoResetID-r19 is the same as the value of ltm-ServingCellNoResetID (reset identification information). Specifically, control unit 240 may determine that a PDCP anchor change is unnecessary when the value of ltm-NoResetID-r19 and the value of ltm-ServingCellNoResetID are the same. On the other hand, control unit 240 may determine that a PDCP anchor change is necessary when the value of ltm-NoResetID-r19 and the value of ltm-ServingCellNoResetID are different.

[0102] (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 relating to Inter-CU LTM.

[0103] (3.1) Prerequisites and Issues As described above, not only Intra-CU LTM but also Inter-CU LTM may be supported in the wireless communication system 10. Furthermore, a transition that changes only the control plane (CP) and maintains the user plane (UP), that is, Inter-CU LTM without PDCP anchor change, which does not require a PDCP setting change (PDCP anchor change), may be applied.

[0104] Furthermore, in Inter-CU LTM, ltm-NoResetID-r19 may be introduced as described above to realize L2 Reset (which may be interpreted as re-establishment of RLC and PDCP). In other words, ltm-NoResetID-r18 and ltm-NoResetID-r19 may coexist.

[0105] Figure 5 shows an example in which a PDCP anchor change is not required in inter-CU LTM. Figure 6 shows an example in which a PDCP anchor change is required in inter-CU LTM. As shown in Figure 5, if the value (1) of ltm-ServingCellNoResetID of the serving cell and the value (1) of ltm-NoResetID-r19 of the LTM candidate cell are the same (match), a PDCP anchor change may not be required.

[0106] On the other hand, as shown in FIG. 6, if the value (1) of the ltm-ServingCellNoResetID of the serving cell is different from the value (2) of the ltm-NoResetID-r19 of the LTM candidate cell, a PDCP anchor change may be necessary.

[0107] In the case of Intra-CU LTM, if the serving cell and candidate cell are formed by the same DU, L2 Reset (such as re-establishment of RLC) is not required, and if the serving cell and candidate cell are formed by different DUs, it may be determined unequivocally that L2 Reset is required. In this way, since Intra-CU LTM is based on the premise that they are under the control of the same CU, the CU can easily determine whether the serving cell and candidate cell are formed by the same DU without exchanging information with other RAN nodes.

[0108] However, in the case of Inter-CU LTM, since a UE transitions between different CUs, it is necessary for RAN (Radio Access Network) nodes such as gNBs that may be involved in the transition to recognize whether the serving cell and candidate cell use the same PDCP setting (which may also be referred to as a PDCP anchor, a PDCP entity, or a PDCP termination point). Basically, in the case of Inter-CU LTM across CUs, the PDCP anchor also changes as a rule, but as mentioned above, Inter-CU LTM without PDCP anchor change is being considered.

[0109] When Inter-CU LTM without PDCP anchor change is introduced, PDCP setting changes may not be necessary even in the case of UE transition (handover) across gNBs (CUs). However, RAN nodes such as gNBs that may be involved in the transition cannot recognize the configuration status of lower layers, including PDCP. Therefore, they may not be able to properly support Inter-CU LTM without PDCP anchor change.

[0110] An example of operation that can solve this problem will be described below.

[0111] (3.2) Example of operation Figure 7 shows an example of a cell information exchange sequence between RAN nodes. As shown in Figure 7, a RAN node may exchange cell lists (e.g., cell #1, cell #2, cell #3, etc.) using the same PDCP anchor with other RAN nodes via the Xn interface. The RAN node may refer to a RAN node in the Xn interface (e.g., 3GPP TS38.423), and may typically be interpreted as a gNB (CU).

[0112] The RAN node may explicitly (or implicitly) indicate to other RAN nodes whether or not the same PDCP anchor is used for the cell or each LTM candidate cell.

[0113] Figure 8 shows an example 1 of the cell information exchange sequence between a source gNB and a target gNB. As shown in Figure 8, the source gNB from which the UE is transferred may exchange a cell list that uses the same PDCP anchor as the serving cell with the target gNB to which the UE is transferred during the handover procedure. Note that the source gNB (or target gNB) may explicitly (or implicitly) instruct other RAN nodes whether or not the cell or each LTM candidate cell uses the same PDCP anchor as the serving cell.

[0114] Figure 9 shows example 2 of the cell information exchange sequence between the source gNB and the target gNB. As shown in Figure 9, the source gNB may exchange the above-mentioned Cell list with the target gNB in ​​the handover procedure via AMF. Specifically, the source gNB may send a Handover Required message including the Cell list to the target gNB via AMF.

[0115] In addition, a RAN node such as a source gNB may exchange a cell list using a PDCP anchor different from that of the serving cell with another RAN node during the handover procedure. Alternatively, whether or not a PDCP anchor different from that of the serving cell is used may be explicitly (or implicitly) indicated to the other RAN node.

[0116] Fig. 10 shows an example of a cell information exchange sequence between a CU and a DU. The DU may be separated from the CU and installed in a geographically different location (CU-DU split). As shown in Fig. 10, the CU may exchange a list of cells using the same PDCP anchor with the DU. The CU may explicitly (or implicitly) instruct the DU whether the same PDCP anchor is used for each cell or each LTM candidate cell.

[0117] The CU may also exchange with the DU a list of cells that use the same PDCP anchor as the serving cell. Note that the CU may explicitly (or implicitly) indicate to the DU whether the cell or each LTM candidate cell uses the same PDCP anchor as the serving cell.

[0118] Alternatively, the CU may exchange with the DU a cell list that uses a PDCP anchor different from that of the serving cell, or the CU may explicitly (or implicitly) indicate to the DU whether or not the CU uses a PDCP anchor different from that of the serving cell.

[0119] According to the operation example described above, a RAN node such as a gNB can exchange lists of cells using the same PDCP anchor (or different PDCP anchors) with other RAN nodes. Therefore, even when Inter-CU LTM without PDCP anchor change is applied, related RAN nodes can reliably recognize in advance whether a PDCP anchor change is required. As a result, even when Inter-CU LTM is executed, appropriate UE transition can be achieved between RAN nodes related to the UE transition according to the configuration status of lower layers.

[0120] In this embodiment, the above-mentioned lists can be exchanged during the handover procedure or between the CU and DU, so that RAN nodes that may be involved in Inter-CU LTM can efficiently and reliably determine whether a PDCP anchor change is required.

[0121] (4) Other embodiments The contents of the present proposal have been explained above in accordance with the embodiments, 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.

[0122] 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 also be interchangeable.

[0123] Furthermore, specific, dedicated, UE-specific, and UE-dedicated may be interchangeable. Similarly, common, shared, group-common, UE-common, and UE-shared may be interchangeable.

[0124] In the present 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.

[0125] The block diagrams (Fig. 3.4) 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. 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 (for example, by wire, wirelessly, etc.) and these multiple devices. The functional block may be realized by combining software with the single device or multiple devices.

[0126] 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.

[0127] 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. Fig. 11 is a diagram showing an example of the hardware configuration of the device. As shown in Fig. 11, 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.

[0128] 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.

[0129] 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.

[0130] 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.

[0131] 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.

[0132] 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.

[0133] 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.

[0134] 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.

[0135] 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.

[0136] 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).

[0137] 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).

[0138] 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.

[0139] 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.

[0140] 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.

[0141] 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.

[0142] 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.

[0143] 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.

[0144] 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.

[0145] The input and output information may be stored in a specific location (for example, memory) or may be managed using a management table. The input and output information may be overwritten, updated, or added to. The output information may be deleted. The input information may be sent to another device.

[0146] 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).

[0147] 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).

[0148] 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.

[0149] 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.

[0150] 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.

[0151] 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.

[0152] As used in this disclosure, the terms "system" and "network" are used interchangeably.

[0153] 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.

[0154] 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.

[0155] 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.

[0156] 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)).

[0157] 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.

[0158] 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.

[0159] In this disclosure, the terms "Mobile Station (MS)," "user terminal," "User Equipment (UE)," "terminal," etc. may be used interchangeably.

[0160] 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.

[0161] 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 an autonomous mobile object operating 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.

[0162] 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).

[0163] 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.

[0164] 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.

[0165] 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.

[0166] 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.

[0167] 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.

[0168] 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.

[0169] 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.

[0170] 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.

[0171] 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.

[0172] 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.

[0173] 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.

[0174] 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.

[0175] 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.

[0176] 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.

[0177] 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.

[0178] 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.

[0179] 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.

[0180] 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.

[0181] 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."

[0182] 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.

[0183] 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.

[0184] The reference signal may also be abbreviated as Reference Signal (RS), and may also be called a pilot depending on the applicable standard.

[0185] 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."

[0186] The "means" in the configuration of each of the above devices may be replaced with "part," "circuit," "device," etc.

[0187] 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.

[0188] 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.

[0189] 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.

[0190] 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.

[0191] 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."

[0192] Fig. 12 shows an example of the configuration of a vehicle 2001. As shown in Fig. 12, 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.

[0193] 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).

[0194] 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.

[0195] 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.

[0196] 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.

[0197] 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.

[0198] 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.

[0199] 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.

[0200] 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.

[0201] 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. [Explanation of symbols]

[0202] 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 Measurement report section 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 performs mobility control in a lower layer; a transmitter that transmits cell information indicating a cell using the same setting in the lower layer to another radio base station; A radio base station comprising:

2. a control unit that performs mobility control in a lower layer; a transmitter for transmitting a handover-related message including cell information indicating a cell using the same or different setting in the lower layer to another radio base station or another network device; A radio base station comprising:

3. A radio base station including a first device and one or more second devices connected to the first device, The first device is a control unit that performs mobility control in a lower layer; a transmitter configured to transmit, to the second device, cell information indicating a cell for which the first device and the second device use the same setting in the lower layer; A radio base station comprising:

4. A radio base station including a first device and one or more second devices connected to the first device, The first device is a control unit that performs mobility control in a lower layer; a transmitting unit that transmits cell information indicating a cell that uses the same configuration in the lower layer as a serving cell or a configuration in the lower layer that is different from that of the serving cell to the second device; A radio base station comprising:

5. performing mobility control at a lower layer; transmitting cell information indicating cells using the same setting in the lower layer to other radio base stations; A wireless communication method in a wireless base station, comprising:

6. performing mobility control at a lower layer; transmitting a handover-related message to another radio base station or another network device, the handover-related message including cell information indicating cells using the same or different configuration in the lower layer; A wireless communication method in a wireless base station, comprising:

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