Terminal and communication method

Abstract

To provide a terminal and a communication method capable of appropriately reporting CSI measurement results.SOLUTION: A terminal includes a control unit that measures channel state information and a transmission unit that transmits the measurement results of the channel state information to candidate cells, and the control unit selects some candidate cells from the set candidate cells and measures the channel state information preferentially for the selected candidate cells.SELECTED DRAWING: Figure 8

Description

[Technical Field]

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

[0002] The 3rd Generation Partnership Project (3GPP (registered trademark)) has specified the 5th generation mobile communication system (also known as 5G, New Radio (NR) or Next Generation 10 (NG)), and is also working on specifications for the next generation of mobile communication systems, 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 addition, in Conditional LTM, specifically UE-triggered LTM, like conditional handover (CHO), the UE receives a specific execution condition from the radio base station (gNB), monitors the status according to the execution condition, and executes handover to another cell if the execution condition is satisfied. Furthermore, LTM enables HO (RACH less HO) without a random access procedure (RA procedure).

[0005] In the case of RACH less HO, a random access response (RAR) from the gNB to the UE is omitted, so the UE cannot know the timing advance (TA) to be applied in the target cell. Therefore, a method (early TA acquisition) has been specified 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 (Non-Patent Document 2). The TA acquired by the target cell through early TA acquisition is notified to the UE by a Cell Switch Command MAC-CE. In early TA acquisition, early synchronization specified in 3GPP TS38.300 may be performed. [Prior art documents] [Non-patent literature]

[0006] [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] 3GPP TS 38.401 V18.0.0, 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NG-RAN; Architecture description (Release 18), 3GPP, December 2023 Summary of the Invention

[0007] To maintain high throughput after a handover, the candidate cell must acquire CSI (Channel State Information) measurement results from the UE early.

[0008] However, a specific scheme for reporting CSI measurement results has not yet been fully considered.

[0009] One aspect of the present disclosure provides a terminal and a communication method that can appropriately report CSI measurement results.

[0010] A terminal according to one aspect of the present disclosure includes a control unit that measures channel state information and a transmission unit that transmits the measurement results of the channel state information to candidate cells, and the control unit selects some candidate cells from among the set candidate cells and prioritizes the measurement of the channel state information for the selected candidate cells. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram illustrating an overall schematic configuration of a wireless communication system. [Figure 2] FIG. 10 is a diagram illustrating an example of control using LTM (L1 / L2 mobility). [Figure 3] FIG. 1 is a functional block diagram of a gNB. [Figure 4] FIG. 2 is a functional block diagram of a UE. [Figure 5] FIG. 1 is a sequence diagram showing a conventional method for transmitting CSI measurement results. [Figure 6] FIG. 1 is a diagram illustrating a conventional solution for solving the problem of data rate reduction after cell switching. [Figure 7] FIG. 10 is a sequence diagram illustrating a first CSI measurement result transmission method according to Proposal 1 of the present disclosure. [Figure 8] FIG. 10 is a sequence diagram illustrating a second CSI measurement result transmission method according to Proposal 1 of the present disclosure. [Figure 9] FIG. 10 is a sequence diagram illustrating a first CSI measurement result transmission method according to Proposal 3 of the present disclosure. [Figure 10] FIG. 1 is a sequence diagram showing a conventional method for transmitting CSI measurement results. [Figure 11] FIG. 1 is a sequence diagram showing a conventional method for transmitting CSI measurement results. [Figure 12] FIG. 10 is a sequence diagram showing a method of transmitting CSI measurement results in the case of Intra-CU LTM in Proposal 4 of the present disclosure. [Figure 13] FIG. 10 is a sequence diagram showing a method of transmitting CSI measurement results in the case of Inter-CU LTM in Proposal 4 of the present disclosure. [Figure 14] FIG. 2 is a diagram illustrating an example of the hardware configuration of a base station and a terminal. [Figure 15] FIG. 1 is a diagram illustrating an example of a configuration of a vehicle.

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

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

[0014] The wireless communication system 10 may be a wireless communication system conforming to a method called Beyond 5G, 5G Evolution, or 6G, or may include a wireless communication system conforming to a method called Long Term Evolution (LTE) or 4G. The wireless communication system 10 may support functions related to the Industrial Internet of Things (IIoT) and Ultra-Reliable and Low Latency Communications (URLLC).

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

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

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

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

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

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

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

[0022] L3 Mobility may be interpreted as mobility control at the Radio Resource Control layer (RRC), while L1 / L2 Mobility may be interpreted as mobility control at the Physical layer (PHY), Medium Access Control layer (MAC), Radio Link Control layer (RLC), and Packet Data Convergence Protocol layer (PDCP) (mobility control by lower layers).

[0023] LTM may include network-triggered LTM and UE-triggered LTM (Conditional LTM, UE-triggered LTM).

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] In the case of RACH less HO, a random access response (RAR) from the gNB to the UE is omitted, so the UE 200 cannot know the timing adjustment value to be applied in the target cell. Therefore, in the wireless communication system 10, a method (early TA acquisition) in which the target cell (which may also be called a target gNB, a candidate cell, etc.) acquires a TA for its own cell in advance may be applied. The TA acquired by the target cell through early TA acquisition is notified to the UE by a Cell Switch Command MAC-CE. In the early TA acquisition, early synchronization specified in 3GPP TS38.300 may be executed.

[0030] In addition, in the wireless communication system 10, in the case of LTM, for the random access channel (PRACH: Physical Random Access Channel), a random access preamble is transmitted in response to an instruction from the PDCCH (Physical Downlink Control Channel), and a PDCCH ordered RACH without RAR, in which the RAR can be omitted, and a PDCCH ordered RACH with RAR, in which the RAR is transmitted from the target cell without omitting the RAR, may be executed.

[0031] RACH less HO (early TA acquisition) is described in 3GPP TS38.401, Chapter 8.2.1.5, etc. Also, PDCCH ordered RACH without RAR is described in 3GPP TS38.300, Chapter 9.2.3.5.2, etc.

[0032] 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.

[0033] 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 candidates), and timer management for determining whether HO is successful.

[0034] 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.

[0035] The UE 200 reports CSI measurement results including reception qualities for cells including the serving cell and neighboring cells to the network. The procedure in which the UE 200 performs CSI measurement and reports the CSI measurement results may be referred to as measurement reporting. The reception qualities for the cells may include reception qualities of beams from the cells, or reception qualities of cells based on beams from the cells.

[0036] The UE 200 may periodically report the CSI measurement result. Alternatively, the UE 200 may report the CSI measurement result for each event. An entering condition for starting CSI measurement and a leaving condition for ending the CSI measurement result report 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 the UE triggered LTM.

[0037] 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).

[0038] The data channels include a physical downlink shared channel (PDSCH) and a physical uplink shared channel (PUSCH).

[0039] 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.

[0040] (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.

[0041] (2.1) gNB100 As shown in FIG. 3, the gNB 100 includes a radio communication unit 110, a handover processing unit 120, an RA procedure management unit 130, and a control unit 140.

[0042] The wireless communication unit 110 transmits downlink signals (DL signals) conforming to NR, and also receives uplink signals (UL signals) conforming to NR.

[0043] 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).

[0044] 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 multiple beams to another cell.

[0045] The serving cell may be interpreted simply 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 referring to a set of one or more cells including the primary cell and all secondary cells.

[0046] 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 Restablishment Request to the candidate target cell.

[0047] The RA procedure management unit 130 manages operations related to a random access procedure (RA procedure) with the UE 200. The RA procedure management unit 130 also sets a timing advance (TA) value and the like.

[0048] Specifically, the RA procedure management unit 130 may manage the RACH (RA procedure method applied to the UE 200. More specifically, the RA procedure management unit 130 may apply either a PDCCH ordered RACH without RAR or a PDCCH ordered RACH with RAR to the UE 200.

[0049] In this embodiment, the RA procedure management unit 130 may receive a random access preamble transmitted from the UE 200. In this embodiment, the RA procedure management unit 130 may constitute a receiving unit that receives the random access preamble.

[0050] The RA procedure management unit 130 may receive an acknowledgement response indicating that the UE 200 has received the random access response (RAR) from the UE 200. In this embodiment, the RA procedure management unit 130 may constitute a receiving unit that receives the acknowledgement response.

[0051] The RA procedure management unit 130 may receive failure information indicating that the random access procedure (RA procedure) has failed from the UE 200. In this embodiment, the RA procedure management unit 130 may constitute a receiving unit that receives the failure information.

[0052] In addition, the RA procedure management unit 130 may transmit a timing adjustment value (TA) to the source cell of the UE 200 when the radio communication unit 110 receives an acknowledgement indicating that the gNB 100 forms a target cell and the UE 200 has received a random access response (RAR).

[0053] Alternatively, the RA procedure management unit 130 may transmit, to the source cell, an indication indicating that the gNB 100 forms the target cell and that the UE 200 has acquired the TA. The TA may refer to a TA applied in the target cell, and may be a TA included in a PDCCH ordered RACH without RAR or a PDCCH ordered RACH with RAR. In this embodiment, the RA procedure management unit 130 may configure a transmission unit that transmits, to the source cell, at least one of the timing adjustment value and an indication indicating that the UE 200 has acquired the timing adjustment value.

[0054] The RA procedure management unit 130 can set a TA value to be applied to the own cell, etc. (a cell or beam formed by the gNB 100).

[0055] 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).

[0056] 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.

[0057] In this embodiment, the control unit 140 may perform early acquisition of a timing adjustment value of a target cell with the UE 200 that performs cell transition to the target cell without performing a random access procedure. Specifically, the control unit 140 may perform early TA acquisition with the UE 200 that performs RACH less HO.

[0058] Furthermore, for UE 200 that executes cell transfer regardless of an instruction from the network when an execution condition is satisfied, such as Conditional LTM (UE triggered LTM), control unit 140 may determine whether to activate or deactivate the execution condition.

[0059] If the control unit 140 does not receive a random access preamble within a specific time, the control unit 140 may assume that the UE 200 has received a random access response. Specifically, if the control unit 140 does not receive a random access preamble from the UE 200 within a time defined by an ra-ResponseWindow (which may also be referred to as a reception time frame), the control unit 140 may assume that the UE 200 has received an RAR. Here, the state in which the random access preamble is not received from the UE 200 may mean that the UE 200 successfully receives the RAR and does not retransmit the random access preamble with power ramping applied. In other words, if the control unit 140 does not receive a random access preamble from the UE 200 after transmitting the RAR, the control unit 140 may assume that the UE 200 has successfully received the RAR.

[0060] (2.2)UE200 As shown in FIG. 4, the UE 200 includes a radio communication unit 210, an RA execution unit 220, a handover execution unit 230, and a control unit 240.

[0061] 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.

[0062] The RA execution unit 220 executes a random access procedure (RA procedure) with the gNB 100. Specifically, the RA execution unit 220 may execute the RA procedure in accordance with a PDCCH ordered RACH without RAR or a PDCCH ordered RACH with RAR.

[0063] 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.

[0064] The handover executor 230 may also perform processes related to normal handover (legacy handover), handover according to LTM (L1 / L2 Mobility), conditional handover (CHO), and DAPS handover. The handover executor 230 may also support RACH less HO (RACH less LTM).

[0065] Furthermore, the handover execution unit 230 may execute early TA acquisition in order to execute RACH less HO.

[0066] 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 Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ), or Signal-to-Interference plus Noise power Ratio (SINR).

[0067] 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.

[0068] The type of the command is not particularly limited, but may be, for example, an L1 / L2 Mobility command (for example, Cell Switch Command MAC-CE). The L1 / L2 Mobility command may be replaced with another command of the RRC layer.

[0069] 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.

[0070] Furthermore, the control unit 240 can execute 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 execute handover in accordance with mobility control by a lower layer. Specifically, the control unit 240 can execute LTM and control transmission of a random access preamble assuming reception of a random access response, based on a command via a downlink control channel (or a PDCCH ordered RACH with RAR).

[0071] (3) Previous proposals regarding transmission of CSI measurement results In the field of wireless communications, a decrease in UE throughput during handover has long been pointed out as an issue.

[0072] Rel-18 LTM introduces functions to perform RACH-less HO and handover without L2 reset, thereby improving the degradation of UE throughput during cell switch.

[0073] However, to maintain high throughput after a handover, the candidate cell (target gNB) must acquire CSI measurements from the UE early.

[0074] In contribution R1-2407146, the following proposal is made to solve the above problem. Proposal 17: Support target cell measurements before LTM cell switching to support link adaptation immediately after cell switching. Proposal 18: RAN1 will study how to report CSI measurement results to the target cell. Proposal 19: Support reporting of CRI, CQI, PMI and RI of the Type I codebook of the target cell before or after an LTM cell switch.

[0075] The CSI measurement results must be transmitted to the target cell. Contribution R1-2407146 proposes the following two methods for transmitting the CSI measurement results: 1. The UE reports the CSI measurement results to the serving cell, which then forwards the CSI measurement results to the associated target cell, which then uses the CSI measurement results after cell switching (see Figure 5, left). 2. The UE reports the CSI measurement results in the first transmission to the target cell. In this case, the UE should include the CSI measurement results in the same UL transmission that includes the RRC reconfiguration (see Figure 5, right).

[0076] In addition, the following issues are raised in contribution R2-2407201: Observation 2: The inability to easily report the target's channel state information (CSI) as soon as the required measurements are performed delays the configuration of an efficient MCS on the target side, leading to a reduction in DL data rates after cell switching and impacting real-time services.

[0077] In contribution R2-2407201, the following proposal is made to solve this problem. Proposal 3: RAN2 is working on a solution to solve the problem of data rate degradation after cell switching (see Figure 6).

[0078] The analysis and proposals in this disclosure will be described below.

[0079] <Analysis 1> As described above, in LTM, in order to prevent a decrease in the throughput of the UE performing the cell switch at the time of cell switch, the candidate gNB for the cell switch needs to obtain measured CSI information (e.g., channel quality indicator: CQI) at an early stage.

[0080] By acquiring CSI information at an early stage after an LTM cell switch, the network can adaptively control the transmission speed, coding rate, and transmission power allocation of the modulation scheme by directly performing link adaptation on the PDSCH and PDCCH.

[0081] As mentioned above, contribution R1-2407146 proposes two methods for transmitting CSI measurement results.

[0082] However, there has not yet been sufficient discussion about when a UE should start measuring CSI of candidate cells. For example, because CSI changes rapidly over time before and after a cell switch, if a UE measures CSI too early, the measurement results may become unavailable after the cell switch. On the other hand, if CSI measurement is performed too late, a cell switch may be performed before the CSI measurement is complete.

[0083] <Proposal 1> Below, we will explain the proposals (options 1 to 7) for solving the issues presented in Analysis 1 above.

[0084] [Option 1] The UE may start CSI measurement when it receives an RRCReconfiguration message including the LTM configuration from the source gNB. The RRCReconfiguration message may include the CSI configuration of the LTM candidate cells and an instruction to perform CSI measurement on the LTM candidate cells (see Figure 7(1)).

[0085] [Option 2] The UE may start CSI measurement of LTM candidate cells when it receives an early TA acquisition instruction (PDCCH order) from the source gNB (see Figure 1 (2)).

[0086] [Option 2a] When the UE receives a new PDCCH order from the source gNB, the UE may start CSI measurement of the LTM candidate cells (see FIG. 7(2)).

[0087] [Option 3] The UE may start CSI measurement of the LTM candidate cell when it receives a PDCCH instruction (including an instruction to perform CSI measurement of the LTM candidate cell) from the source gNB (see Figure 7 (2)).

[0088] [Option 4] The UE may start CSI measurement of the LTM candidate cell when it receives a MAC CE (including an instruction to perform CSI measurement of the LTM candidate cell) from the source gNB (see Figure 7(2)).

[0089] [Option 5] When the UE receives an LTM cell switch command from the source gNB, the UE may start CSI measurement of LTM candidate cells (see FIG. 7(3)).

[0090] [Option 6] In conditional LTM, the UE may start CSI measurement of LTM candidate cells when it receives an LTM execution condition activation indication from the source gNB (when it starts monitoring the LTM execution condition) (see Figure 8 (3)).

[0091] [Option 6a] In conditional LTM, the UE may start CSI measurement of LTM candidate cells when it receives an LTM execution condition config from the source gNB (see Figure 8 (3)).

[0092] [Option 7] In conditional LTM, the UE may start CSI measurement of LTM candidate cells when the LTM execution condition is satisfied (see FIG. 8(4)).

[0093] (Example) As shown in Figure 1(1), the UE may start CSI measurement when it receives an RRC Reconfiguration including LTM configuration from the source gNB. The UE sends an RRCReconfigurationComplete to the source gNB. The source gNB sends an UL RRC MESSAGE TRANSFER (RRCReconfigurationComplete) to the CU.

[0094] As shown in Figure 7 (2), the UE may start CSI measurement of LTM candidate cells when it receives an early TA acquisition instruction (PDCCH order) from the source gNB. The UE transmits a RACH preamble to the target gNB. The target gNB transfers the TA value to the CU via the F1 interface, and the CU transfers the TA value to the source gNB via the F1 interface. The UE transmits an L1 measurement report to the source gNB. The source gNB, having received the L1 measurement report, determines a cell switch and transmits an LTM cell switch command to the UE.

[0095] As shown in FIG. 7(3), the UE may start CSI measurement of LTM candidate cells when it receives an LTM cell switch command from the source gNB.

[0096] Note that (1) and (2) in FIG. 8 are the same as (1) and (2) in FIG. 7, and therefore the explanation will be omitted.

[0097] As shown in Figure 8(3), in conditional LTM, the UE may start CSI measurement of LTM candidate cells when it receives an LTM execution condition activation instruction from the source gNB (when it starts monitoring the LTM execution condition).

[0098] As shown in FIG. 8(4), in conditional LTM, a UE may start CSI measurement of a candidate cell for LTM when an LTM execution condition is satisfied.

[0099] In option 2 or 3, DCI format 1_0 is used for scheduling PDSCH in one DL cell. This DCI format 1_0 may be configured to provide a CSI measurement field indicated by a 1 or 0 bit to indicate whether the UE should start CSI measurement in the LTM candidate cell. Here, a 1 bit means that the UE needs to start CSI measurement in the LTM candidate cell, and a 0 bit means that it does not.

[0100] (effect) According to the method shown in the above-mentioned option, the UE can start CSI measurement of LTM candidate cells, perform CSI measurement at the appropriate time, and report it to the source gNB before a cell switch occurs.

[0101] <Analysis 2> In LTM, a maximum of eight candidate cells can be configured for a UE. However, it takes time and power consumption for the UE to measure the CSI of all candidate cells immediately before a cell switch. In this case, there is a risk that a cell switch will be performed before the CSI measurements of some candidate cells are completed.

[0102] <Proposal 2> Below, we will explain the proposals (options 1 to 6) for solving the issues presented in Analysis 2 above.

[0103] [Option 1] The UE may select some candidate cells from the configured candidate cells and perform CSI measurement on them preferentially.

[0104] [Option 2] The Source gNB may instruct the UE on which candidate cell to prioritize for CSI measurement among the candidate cells configured in the UE.

[0105] [Option 3] The Source gNB may instruct the UE via an RRC Reconfiguration message / MAC CE / PDCCH the candidate cell ID(s) or LTM config ID of the candidate cell for CSI measurement regarding which candidate cell CSI measurement should be performed.

[0106] [Option 4] The Source gNB may select a candidate cell for CSI measurement based on the L1 / L3 measurement report reported by the UE. For example, among eight LTM candidate cells, the Source gNB may select candidate cells with the top three qualities (L1 RSRP / RSRQ / SINR or L3 RSRP / RSRQ / SINR) as the CSI measurement targets.

[0107] [Option 5] If the UE has an artificial intelligence (AI) or machine learning (ML) model, it may use the AI ​​or machine learning (ML) to predict which candidate cell among the configured candidate cells to measure CSI in. In addition, the UE may notify the gNB of the selection result predicted by the AI ​​or machine learning (ML).

[0108] [Option 6] The Source gNB may select a candidate cell for CSI measurement based on the UE trajectory reported by the UE or the future UE trajectory or route information (in the case of a drone UE) predicted by artificial intelligence (AI) or machine learning (ML). For example, the Source gNB may select the CSI measurement target from among eight LTM candidate cells based on the candidate cell closest to the UE trajectory or route information.

[0109] (effect) According to the method shown in the above-mentioned option, the UE can narrow down the CSI measurements to suitable candidate cells from among a large number of candidate cells, thereby reducing the time and power consumption required by the UE for CSI measurements.

[0110] <Analysis 3> As mentioned above, contribution R1-2407146 proposes two methods for transmitting CSI measurement results.

[0111] <Proposal 3> In addition to the above method, the present disclosure proposes the following two methods.

[0112] (Method 1) In Conditional LTM, PDCCH ordered RACH with RAR may be supported. As shown in Figure 9, the source gNB transmits a PDCCH order to the UE. After transmitting a RACH preamble to the target gNB, the UE receives a Random Access Response (RAR) from the target gNB. The RAR may include a UL grant for transmitting the CSI measurement results to the LTM candidate cell. The UE uses the UL grant to report the CSI measurement results to the LTM candidate cell. The UL grant is physical control channel information that notifies the UE of the timing at which data can be transmitted.

[0113] (Method 2) The CSI measurement results may be transmitted to the LTM candidate cell using a configured grant (e.g., cg-LTM-Configuration) set by the network.

[0114] <Analysis 4> As described above, in the first method, contribution R1-2407146 proposes transmitting CSI measurement results from a serving cell to a target cell. However, contribution R1-2407146 does not mention a specific method for transmitting CSI measurement results. In particular, F1 / Xn / NG signaling has not been considered.

[0115] When using CSI transmitted via the transport network, as shown in Figure 10, the UE receives several reference signals from the target cell while communicating with the serving cell. The UE sends an RSRP to the serving cell and then transmits CSI to the serving cell. The serving cell forwards the CSI to the target cell and sends a Cell switch command to the UE. The target cell then uses the CSI measurement results after the cell switch.

[0116] When the target cell uses the CSI measurement results transmitted to the target after the cell switch, as shown in Figure 11, the UE receives several reference signals from the target cell while the UE and the serving cell are communicating. The UE transmits an RSRP to the serving cell and then transmits CSI to the serving cell. The serving cell transmits a Cell switch command to the UE. The target cell then uses the CSI measurement results after the cell switch.

[0117] <Suggestion 4> (Intra-CU LTM) As shown in Figure 12, after preparing the LTM, the Source gNB-DU sends RRCReconfiguration to the UE. The UE sends RRCReconfigurationComplete to the Source gNB-DU. The Source gNB-DU sends an UL RRC MESSAGE TRANSFER (RRCReconfigurationComplete) to the CU. The Source gNB-DU instructs the UE to measure CSI using the PDCCH order / PDCCH / MAC CE.

[0118] The UE performs CSI measurements and transmits the CSI measurement results to the Source gNB-DU. After receiving the CSI measurement results from the UE, the Source gNB-DU may transmit the CSI measurement results to the CU via the F1-AP interface in a New DU-CU CSI information transfer message. The CU may transmit the CSI measurement results to the target DU in a New CU-DU CSI information transfer message.

[0119] The UE sends an L1 measurement report to the source gNB-DU, and the source gNB-DU makes a cell switch decision and sends an LTM cell switch command to the UE.

[0120] In the above process, the CSI measurement result may be containerized, and the CSI measurement result may be associated with an LTM candidate cell ID (config ID) or a beam index (SSB or CSI-RS index).

[0121] Alternatively, after the Source gNB-DU receives the CSI measurement results from the UE, the Source DU may send the CSI measurement results to the CU via an Existing DU-CU TA information transfer message over the F1-AP interface.

[0122] The CU may transmit the CSI measurement results to the target DU via an existing CU-DU TA information transfer message. The CSI measurement results may be containerized. The CSI measurement results may be associated with the LTM candidate cell ID (config ID) or beam index (SSB or CSI-RS index).

[0123] (Inter-CU LTM (Xn handover)) As shown in Figure 13, after preparing the LTM, the Source gNB-DU sends an RRCReconfiguration to the UE. The UE sends an RRCReconfigurationComplete to the Source gNB-DU. The Source gNB-DU instructs the UE to measure CSI using the PDCCH order / PDCCH / MAC CE.

[0124] The UE performs CSI measurements and transmits the CSI measurement results to the Source gNB-DU. After receiving the CSI measurement results from the UE, the Source gNB-DU may transmit the CSI measurement results to the target gNB via the Xn-AP interface in an RRC transfer message. The CSI measurement results may be containerized. The CSI measurement results may be associated with the LTM candidate cell ID (config ID) or beam index (SSB or CSI-RS index).

[0125] Alternatively, after receiving the CSI measurement results from the UE, the source gNB may transmit the CSI measurement results to the target gNB via the Xn-AP interface in a new CSI transfer message. The CSI measurement results may be containerized. The CSI measurement results may be associated with the LTM candidate cell ID (config ID) or beam index (SSB or CSI-RS index).

[0126] The UE sends an L1 measurement report to the source gNB-DU, and the source gNB-DU makes a cell switch decision and sends an LTM cell switch command to the UE.

[0127] (In the case of Inter-CU LTM (NG handover)) After receiving the CSI measurement results from the UE, the source gNB may transmit the CSI measurement results to the AMF over the NG-AP interface. The AMF may then transmit the CSI measurement results to the target gNB. The CSI measurement results may be containerized. The CSI measurement results may be associated with the LTM candidate cell ID (config ID) or beam index (SSB or CSI-RS index).

[0128] <Variations of Analysis 4> The UE capability for the UE to measure CSI and transmit to an early LTM candidate cell has not been considered.

[0129] <Variation of Proposal 4> The UE may implement a new UE capability that performs CSI measurement of an LTM candidate cell and transmits the CSI measurement result to the LTM candidate cell early. This UE capability may be called early CSI measurement reporting.

[0130] The UE may be provided with a new UE capability that performs CSI measurement of an LTM candidate cell and transmits the CSI measurement result to the LTM candidate cell immediately before LTM execution.

[0131] The UE may provide a new UE capability that performs CSI measurement of the LTM candidate cell and transmits the CSI measurement results to the LTM candidate cell in a UL grant included in a random access response transmitted from the target gNB.

[0132] The UE may be provided with a new UE capability that performs CSI measurement of an LTM candidate cell and transmits the CSI measurement result to the LTM candidate cell immediately after LTM execution.

[0133] The UE may be provided with a new UE capability that measures CSI of an LTM candidate cell and transmits the CSI measurement results to the LTM candidate cell using a configured grant (e.g., cg-LTM-Configuration) set on the network side.

[0134] The UE may be provided with a new UE capability for receiving an instruction to measure CSI of an LTM candidate cell in a PDCCH order / PDCCH / MAC CE / RRC message.

[0135] The UE may set a new UE capability for preferentially measuring CSI of some candidate cells among LTM candidate cells in the PDCCH order / PDCCH / MAC CE / RRC message.

[0136] The UE may be provided with a new UE capability for receiving, from the network, an instruction to perform CSI measurement preferentially on some candidate cells among LTM candidate cells in a PDCCH order / PDCCH / MAC CE / RRC message.

[0137] <UE capability> The UE may report at least one of the following capabilities to the network (e.g., base station): The capability may indicate, for example, whether a proposal (or an option of a proposal, or an alternative of a proposal) is supported. Capability of each proposal - Capability of each option proposed Ability to combine two or more options in a proposal - Capability of each alternative proposed Ability to combine two or more alternative proposals

[0138] The UE may report the above capabilities for each frequency. Capabilities may be reported for each UE. Capabilities may be reported for each of FR (frequency range) 1, FR2, FR2-1, FR2-2, and FR3. Capabilities may be reported for each SCS (subcarrier spacing). Capabilities may be reported for each band. Capabilities may be reported for each BC (band combination). Capabilities may be reported for each FC (frequency combination). Capabilities may be reported for each FSPC (Feature Set Per Component-carrier).

[0139] The UE may report the above capabilities for each cell. For example, capabilities may be reported for each UE. Capabilities may be reported for each cell. Capabilities may be reported for each TDD (time division duplex). Capabilities may be reported for each FDD (frequency division duplex). Capabilities may be reported for each TDD and FDD.

[0140] <Note 1: How to select options and combinations> With regard to the present disclosure, at least one of whether to apply a proposal, which proposal is applied, which option (or multiple options) is used, and which alternative (or multiple alternatives) is used may be set by a parameter of a higher layer, may be determined by a parameter of a related higher layer, may be indicated by a MAC CE or a DCI, may be determined based on a capability of the UE, or may be defined by a specification. Also, at least one of whether to apply a proposal, which proposal is applied, which option (or multiple options) is used, and which alternative (or multiple alternatives) is used may be based on a condition described in a specification. Also, at least one of whether to apply a proposal, which proposal is applied, which option (or multiple options) is used, and which alternative (or multiple alternatives) is used may be based on a condition described in a specification. At least one of whether to apply a proposal, which proposal to apply, which option(s) to use, and which alternative(s) to use may be determined by at least one of higher layer parameter configuration, MAC CE, DCI, and reported UE capability. At least one of whether to apply a proposal, which proposal to apply, which option(s) to use, and which alternative(s) to use may also be determined by a combination of the above.

[0141] In the present disclosure, multiple options and / or multiple alternatives may be combined into one option or one alternative.

[0142] In the present disclosure, "Serving" may be replaced with any of "Serving Beam / SpCell", "Serving Beam", "SpCell", and "Serving SpCell".

[0143] In the present disclosure, "neighbor" may be replaced with a beam other than the serving beam. Also, "neighbor" may be replaced with a beam other than the SCell.

[0144] <Note 2: Example of signaling from NW to UE> In the present disclosure, the UE may receive at least one of the following types of information from the NW (network). Note that the NW may be replaced by a gNB or a base station. Information via higher layer signaling (e.g., RRC messages, LPP (LTE Positioning Protocol) messages) MAC CE MAC CE with a new LCID (logical channel ID) in the subheader - MAC CE that extends the existing MAC CE (e.g., introducing a new octet) DCI DCI with existing DCI fields and / or newly introduced DCI fields DCI with CRC (cyclic redundancy check) scrambled by existing RNTI (Radio Network Temporary Identifiers) and / or newly introduced RNTI DCI with existing DCI format or newly introduced DCI format - Information on any combination of the above

[0145] In the present disclosure, the UE may receive at least one type of information of the following periodic types from the NW: Option 1: Periodically Option 2: Semi-persistent Option 3: Aperiodic It should be noted that the information of type Option 2 or Option 3 may be triggered by the UE or by instruction from the gNB.

[0146] <Note 3: Example of signaling from NW to UE> In the present disclosure, the UE may receive information of at least one of the following Quasi Co-Location (QCL) rules from the NW. QCL type A QCL type B QCL type C QCL type D

[0147] In this disclosure, the QCL resource RS for each QCL type may be at least one of the following: ·SSB(Synchronization Signal Block) CSI-RS (Channel State Information Reference Signal) with repetition CSI-RS without repetition ·TRS(Tracking Reference Signal) ·PDCCH / PDSCH DMRS(demodulation Reference Signal)

[0148] In the present disclosure, the information from the NW may be set or instructed as at least one of the following: UE common ·UE dedicated Cell specific Cell common -Per UE - CC (component carrier) ·BWP (bandwidth part) -By band - Each cell · Each CG (cell group)

[0149] <Note 4: Example of signaling from UE to NW> In the present disclosure, the UE may report at least one of the following types of information to the NW: Note that the NW may be replaced by a gNB or a base station. Information via higher layer signaling (e.g., RRC messages, LPP (LTE Positioning Protocol) messages) MAC CE MAC CE with a new LCID (logical channel ID) in the subheader - MAC CE that extends the existing MAC CE (e.g., introducing a new octet) UCI UCI of PUCCH or UCI of PUSCH - Information on any combination of the above

[0150] In the present disclosure, the UE may report at least one type of information of the following periodic types to the NW: Option 1: Periodically Option 2: Semi-persistent Option 3: Aperiodic It should be noted that the information of type Option 2 or Option 3 may be triggered by the UE or by instruction from the gNB.

[0151] <Hardware configuration, etc.> The block diagrams used to explain the above embodiments show functional blocks. These functional blocks (components) are realized by any combination of at least one of hardware and 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 directly or indirectly connected (for example, using wires, wirelessly, etc.) and these multiple devices. The functional block may also be realized by combining the single device or multiple devices with software.

[0152] 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, allocation, 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 these functions are implemented.

[0153] For example, a base station, a terminal, etc. according to an embodiment of the present disclosure may function as a computer that performs processing of the communication method of the present disclosure. Fig. 14 is a diagram illustrating an example of the hardware configuration of a base station and a terminal according to an embodiment of the present disclosure. The above-described base station 100 and terminal 200 may be physically 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.

[0154] In the following description, the term "apparatus" can be interpreted as a circuit, a device, a unit, etc. The hardware configuration of base station 100 and terminal 200 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.

[0155] Each function in the base station 100 and the terminal 200 is realized by loading predetermined software (programs) onto hardware such as the processor 1001 and the memory 1002, causing the processor 1001 to perform calculations, control communication by the communication device 1004, and control at least one of reading and writing data in the memory 1002 and the storage 1003.

[0156] The processor 1001 controls the entire computer by running, for example, an operating system. The processor 1001 may be configured by a central processing unit (CPU) including an interface with peripheral devices, a control device, an arithmetic unit, a register, etc. For example, the above-mentioned control unit 103 and control unit 203 may be realized by the processor 1001.

[0157] Furthermore, the processor 1001 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. For example, the control unit 203 of the terminal 200 may be implemented by a control program stored in the memory 1002 and running on the processor 1001, and similar implementations may be made for other functional blocks. While the above-described various processes have been described as being executed by one processor 1001, they may also 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 also be transmitted from a network via a telecommunications line.

[0158] 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 read-only memory (EPROM), an electrically erasable programmable read-only memory (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 executable programs (program codes), software modules, etc. for implementing a communication method according to an embodiment of the present disclosure.

[0159] Storage 1003 is a computer-readable recording medium, and may be composed of at least one of, for example, an optical disk such as a CD-ROM (Compact Disc 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 storage medium may be, for example, a database, a server, or other appropriate medium including at least one of memory 1002 and storage 1003.

[0160] 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 referred to as, for example, a network device, a network controller, a network card, or a communication module. The communication device 1004 may be configured to include a high-frequency switch, a duplexer, a filter, a frequency synthesizer, etc. to realize at least one of frequency division duplex (FDD) and time division duplex (TDD). For example, the above-mentioned transmitter 101, receiver 102, receiver 201, transmitter 202, etc. may be realized by the communication device 1004.

[0161] 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).

[0162] Furthermore, each device, such as the processor 1001 and the memory 1002, is connected by a bus 1007 for communicating information. The bus 1007 may be configured using a single bus, or may be configured using different buses between each device.

[0163] Furthermore, base station 100 and terminal 200 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, processor 1001 may be implemented using at least one of these pieces of hardware.

[0164] (Supplementary explanation of the embodiment) Although the embodiments of the present disclosure have been described above, the disclosed invention is not limited to such embodiments, and those skilled in the art will understand various modifications, alterations, alternatives, and substitutions. While specific numerical examples have been used to facilitate understanding of the invention, unless otherwise specified, these numerical values ​​are merely examples, and any appropriate values ​​may be used. The division of items in the above description is not essential to the present disclosure; features described in two or more items may be used in combination as needed, and features described in one item may apply to features described in another item (unless inconsistent). The boundaries between functional units or processing units in the functional block diagrams do not necessarily correspond to the boundaries between physical components. The operations of multiple functional units may be performed by a single physical component, or the operations of a single functional unit may be performed by multiple physical components. The order of processing steps described in the embodiments may be reversed as long as there is no contradiction. For convenience of processing description, base stations and terminals have been described using functional block diagrams. However, such devices may be implemented using hardware, software, or a combination thereof. The software operated by the processor of a base station in accordance with an embodiment of the present disclosure, and the software operated by the processor of a terminal in accordance with an embodiment of the present disclosure may each be stored in random access memory (RAM), flash memory, read-only memory (ROM), EPROM, EEPROM, registers, hard disk (HDD), removable disk, CD-ROM, database, server, or any other suitable storage medium.

[0165] <Information notification, signaling> The notification of information is not limited to the 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., Radio Resource Control (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.

[0166] <Applicable systems> Embodiments described in the present disclosure may be applied to at least one of a system using LTE (Long Term Evolution), LTE-Advanced (LTE-A), SUPER 3G, IMT-Advanced, 4G (4th generation mobile communication system), 5G (5th generation mobile communication system), 6G (6th generation mobile communication system), xG (xG (x is, for example, an integer or a decimal point)), FRA (Future Radio Access), NR (new Radio), New radio access (NX), Future generation radio access (FX), W-CDMA (registered trademark), GSM (registered trademark), CDMA2000, UMB (Ultra Mobile Broadband), IEEE 802.11 (Wi-Fi (registered trademark)), IEEE 802.16 (WiMAX (registered trademark)), IEEE 802.20, UWB (Ultra-Wideband), Bluetooth (registered trademark), or other suitable systems, and next generation systems extended, modified, created, or defined based on these. Furthermore, a combination of multiple systems (for example, a combination of at least one of LTE and LTE-A with 5G) may be applied.

[0167] <Processing procedures, etc.> 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.

[0168] <Base station operation> In the present disclosure, a specific operation described as being performed by a base station may 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, but not limited to, an MME or an S-GW). 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.

[0169] <Input / output direction> Information, etc. (see the section on information and signals) can be output from a higher layer (or a lower layer) to a lower layer (or a higher layer). It may also be input and output via multiple network nodes.

[0170] <Handling of input and output information> Input and output information may be stored in a specific location (for example, memory) or may be managed using a management table. Input and output information may be overwritten, updated, or added to. Output information may be deleted. Input information may be sent to another device.

[0171] <Judgment method> 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).

[0172] <Variations in form, etc.> 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).

[0173] Although the present disclosure has been described in detail above, it is clear to those skilled in the art that the present disclosure is not limited to the embodiments described herein. The present disclosure can be implemented in modified and altered forms without departing from the spirit and scope of the present disclosure as defined by the claims. Therefore, the description of the present disclosure is intended to be illustrative and does not have any limiting meaning on the present disclosure.

[0174] <Software> 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.

[0175] 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.

[0176] <Information, Signals> 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.

[0177] 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.

[0178] <System, Network> As used in this disclosure, the terms "system" and "network" are used interchangeably.

[0179] <Parameter, channel name> 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.

[0180] 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.

[0181] <Base station> 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.

[0182] A base station can accommodate one or more (e.g., three) cells. 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 service by a base station subsystem (e.g., a small indoor base station (RRH: Remote Radio Head)). The term "cell" or "sector" refers to a part or the entire coverage area of ​​a base station and / or base station subsystem that provides communication service within this coverage.

[0183] 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.

[0184] <Mobile station> In this disclosure, the terms "Mobile Station (MS)," "user terminal," "User Equipment (UE)," "terminal," etc. may be used interchangeably.

[0185] 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.

[0186] <Base station / mobile station> 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.

[0187] Furthermore, a base station in the present disclosure may be read as a terminal. For example, the embodiments of the present disclosure may be applied to a configuration in which communication between a base station and a terminal is replaced with communication between multiple terminals (which may be called, for example, D2D (Device-to-Device) or V2X (Vehicle-to-Everything)). In this case, the terminal may be configured to have the functions of the base station described above. Furthermore, terms such as "uplink" and "downlink" may be read as terms corresponding to communication between terminals (for example, "side"). For example, terms such as an uplink channel and a downlink channel may be read as a side channel.

[0188] Similarly, the term "terminal" in the present disclosure may be read as "base station." In this case, the base station may be configured to have the functions of the terminal described above.

[0189] Fig. 15 shows an example configuration of a vehicle 2001. As shown in Fig. 15, the vehicle 2001 includes a drive unit 2002, a steering unit 2003, an accelerator pedal 2004, a brake pedal 2005, a shift lever 2006, front wheels 2007, 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. Each aspect / embodiment described in the present disclosure may be applied to a communication device mounted on the vehicle 2001, and may be applied to the communication module 2013, for example.

[0190] The drive unit 2002 is configured, for example, by 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.

[0191] 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 2029 provided in the vehicle 2001. The electronic control unit 2010 may also be called an ECU (Electronic Control Unit).

[0192] The signals from the various sensors 2021 to 2029 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.

[0193] 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 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 multimedia information and multimedia services to the occupants of the vehicle 2001.

[0194] 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.

[0195] 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 a millimeter-wave radar, a LiDAR (Light Detection and Ranging), a camera, a positioning locator (e.g., GNSS, etc.), map information (e.g., high-definition (HD) map, autonomous vehicle (AV) map, etc.), a gyro system (e.g., an IMU (Inertial Measurement Unit), an INS (Inertial Navigation System), etc.), an AI (Artificial Intelligence) chip, and an AI processor, 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 the driving assistance function or the autonomous driving function.

[0196] The communication module 2013 can communicate with the microprocessor 2031 and components of the vehicle 2001 via the communication port. For example, the communication module 2013 transmits and receives data via the communication port 2033 to and from the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, front wheels 2007, rear wheels 2008, axle 2009, microprocessor 2031 and memory (ROM, RAM) 2032 in the electronic control unit 2010, and sensors 2021 to 2029, which are provided in the vehicle 2001.

[0197] 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.

[0198] The communication module 2013 may transmit at least one of signals from the above-mentioned various sensors 2021-2029 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 2021-2029, 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.

[0199] The communication module 2013 receives various information (traffic information, traffic signal information, vehicle distance information, etc.) transmitted from external devices and displays it on an information service unit 2012 provided in the vehicle 2001. 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 the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, front wheels 2007, rear wheels 2008, axles 2009, sensors 2021 to 2029, and the like provided in the vehicle 2001.

[0200] <Terminology and interpretation> 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.

[0201] 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.

[0202] <Reference signal> The reference signal may be abbreviated as RS (Reference Signal) or may be called a pilot depending on the applicable standard.

[0203] <The meaning of "based on"> 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."

[0204] <"First", "Second"> 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 or that the first element must in some way precede the second element.

[0205] <Means> In the configurations of each of the above devices, the "means" may be replaced with "section", "circuit", "device", etc.

[0206] <Open format> In the present disclosure, when the terms "include", "including" and their variants are used, these terms are intended to be inclusive, similar to the term "comprising". Further, the term "or" used in the present disclosure is not intended to be an exclusive disjunction.

[0207] <Time units such as TTI, frequency units such as RB, radio frame configuration> 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 referred to as 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 does not depend on numerology.

[0208] Numerology may be a communication parameter applied to at least one of the transmission and reception of a certain signal or channel. Numerology may indicate at least one of, for example, subcarrier spacing (SCS), bandwidth, symbol length, cyclic prefix length, transmission time interval (TTI), number of symbols per TTI, radio frame configuration, specific filtering processing performed by a transceiver in the frequency domain, specific windowing processing performed by a transceiver in the time domain, etc.

[0209] A slot may be composed of one or more symbols (such as an Orthogonal Frequency Division Multiplexing (OFDM) symbol or a Single Carrier Frequency Division Multiple Access (SC-FDMA) symbol) in the time domain. A slot may be a time unit based on numerology.

[0210] A slot may include multiple minislots. Each minislot may consist of one or multiple 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.

[0211] 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.

[0212] 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 (for example, 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.

[0213] 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.

[0214] 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.

[0215] 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.

[0216] 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.

[0217] 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.

[0218] 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.

[0219] 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. One TTI, one subframe, etc. may each be composed of one or more resource blocks.

[0220] 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.

[0221] 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.

[0222] 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.

[0223] 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.

[0224] 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."

[0225] The above-described structures of radio frames, subframes, slots, minislots, symbols, etc. 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, etc. may be changed in various ways.

[0226] <Maximum transmission power> The "maximum transmit power" in this disclosure may mean the maximum value of transmit power, the nominal UE maximum transmit power, or the rated UE maximum transmit power.

[0227] <Article> 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.

[0228] <"Different"> 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." [Industrial Applicability]

[0229] One aspect of the present disclosure is useful in wireless communication systems. [Explanation of symbols]

[0230] 10. Wireless communication systems 20 NG-RAN 100 gNB 110 Radio Communication Department 120 Handover processing unit 130 TA setting section 140 Control Unit 200 UE 210 Radio Communication Department 220 Measurement report section 230 Handover Execution Department 240 Control Unit

Claims

1. a control unit that measures channel state information; a transmitter for transmitting the measurement result of the channel state information to a candidate cell; Equipped with The control unit selects some candidate cells from the set candidate cells and performs measurement of the channel state information preferentially on the selected candidate cells. Terminal.

2. The control unit selects a candidate cell based on an instruction from a network. The terminal according to claim 1 .

3. Candidate cells are selected in order of quality. The terminal according to claim 2.

4. The control unit selects candidate cells using artificial intelligence or machine learning. The terminal according to claim 1 .

5. The device is Select some candidate cells from the set candidate cells, The channel state information is measured preferentially for the selected candidate cell; transmitting the channel state information measurement results to the candidate cells; Communication method.

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