Terminal and communication method

Abstract

To provide a terminal capable of appropriately transmitting a random access preamble with and / or without the assumption of receiving a random access response.SOLUTION: A terminal includes a receiving unit that receives information, and a control unit that determines, on the basis of an instruction via a downlink control channel, one or both of a first transmission of a random access preamble that assumes receipt of a random access response and a second transmission of a random access preamble that does not assume receipt of a random access response, and the control unit determines one or both of the first transmission and the second transmission on the basis of the information.SELECTED DRAWING: Figure 4

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) is developing specifications for the 5th generation mobile communication system (5G, also known as New Radio (NR) or Next Generation (NG)), and is also developing specifications for the next generation, known as Beyond 5G, 5G Evolution, or 6G.

[0003] For example, 3GPP Release 19 discusses extensions to Layer 1 / Layer 2 mobility (L1 / L2 mobility, specifically, Lower Layer Triggered Mobility (LTM)) (see Non-Patent Document 1). LTM is a technology related to the mobility of a terminal (User Equipment, UE) in Layer 1 or Layer 2, and includes the transition of a UE to another cell (handover (HO)). HO using LTM is realized by a lower layer such as the Medium Access Control layer (MAC).

[0004] In 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.

[0006] In the case of LTM, a random access channel (PRACH: Physical Random Access Channel) is specified as a PDCCH ordered RACH without RAR, which transmits a random access preamble in response to a command from a PDCCH (Physical Downlink Control Channel) and can omit the RAR (Non-Patent Document 3). 3GPP Release 19 also considers a PDCCH ordered RACH with RAR, in which the RAR is transmitted from the target cell without omitting the RAR. [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] 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 [Non-patent document 3] 3GPP TS 38.300 V18.1.0, 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NR; NR and NG-RAN Overall Description; Stage 2 (Release 18), 3GPP, March 2024 Summary of the Invention

[0008] For conditional LTM, both PDCCH ordered RACH without RAR and PDCCH ordered RACH with RAR may be supported. It is expected that the UE will be notified whether RAR is present or not, but the mechanism for this is an open issue.

[0009] One aspect of the present disclosure is to provide a terminal and a communication method that can appropriately transmit a random access preamble with and / or without the assumption of receiving a random access response. [Means for solving the problem]

[0010] A terminal according to one embodiment of the present disclosure includes a receiving unit that receives information, and a control unit that determines, based on an instruction via a downlink control channel, one or both of a first transmission of a random access preamble that assumes receipt of a random access response and a second transmission of a random access preamble that does not assume receipt of a random access response, and the control unit determines, based on the information, one or both of the first transmission and the second transmission. [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] This is a functional block diagram of gNB100. [Figure 4] FIG. 2 is a functional block diagram of UE200. [Figure 5] FIG. 10 is a diagram showing an example of a sequence of NW-trigger intra-CU LTM. [Figure 6] This is a diagram showing an example of a sequence of NW-trigger inter-CU LTM. [Figure 7] A diagram showing an example sequence of early TA acquisition (PDCCH ordered RACH without RAR). [Figure 8] A diagram showing an example sequence of early TA acquisition (PDCCH ordered RACH with RAR). [Figure 9] FIG. 10 is a diagram illustrating example LTM-Config message elements. [Figure 10] FIG. 10 is a diagram illustrating example elements of an LTM-Candidate message. [Figure 11] FIG. 10 illustrates example EarlyUL-SyncConfig message elements. [Figure 12] FIG. 10 illustrates example EarlyUL-SyncConfig message elements. [Figure 13] FIG. 1 is a diagram illustrating DCI format 1_0. [Figure 14] FIG. 10 is a diagram illustrating a UE context modification request. [Figure 15] FIG. 10 is a diagram illustrating a Handover request. [Figure 16] FIG. 2 is a diagram illustrating an example of a hardware configuration of a base station and a terminal according to the present embodiment. [Figure 17] FIG. 1 is a diagram illustrating an example of the configuration of a vehicle. DETAILED DESCRIPTION OF THE INVENTION

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

[0013] (1) Overall configuration of 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).

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

[0036] The UE 200 may periodically perform measurement reporting. The UE 200 may perform measurement reporting for each event. An entering condition for starting measurement reporting and a leaving condition for terminating measurement reporting may be defined for each event. The entering condition may be interpreted as a condition for determining whether or not to include a target in measurement reporting, and the leaving condition may be interpreted as a condition for determining whether or not to exclude a target from measurement reporting. At least one of the entering condition and the leaving condition may be applied as an execution condition in 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] More specifically, the RA execution unit 220 may transmit a random access preamble to the network (gNB) based on a command via the downlink control channel (PDCCH) on the assumption that a random access response (RAR) is received. In this embodiment, the RA execution unit 220 may constitute a transmission unit that transmits the random access preamble. The random access preamble may include an index (preamble index) that can identify the random access preamble.

[0064] The RA execution unit 220 may also receive a random access response (RAR) from the network in response to a random access preamble transmitted based on a command via a downlink control channel (PDCCH). In this embodiment, the RA execution unit 220 may constitute a receiving unit that receives the random access response. Note that, although a RACH (which may also be read as an RA procedure) may be initiated by the PDCCH, other physical channels in the downlink direction may be used instead of the PDCCH.

[0065] When the RA execution unit 220 receives a random access response (RAR) in accordance with the PDCCH ordered RACH with RAR, the RA execution unit 220 may transmit an acknowledgement indicating that the RAR has been received to a candidate cell to which the UE is to transfer in accordance with terminal initiated mobility management (LTM) by a lower layer. In this embodiment, the RA execution unit 220 may constitute a transmission unit that transmits the acknowledgement. Specifically, the LTM here may be interpreted as conditional LTM (UE triggered LTM).

[0066] When the RA execution unit 220 receives the RAR, the RA execution unit 220 may transmit acquired information indicating that the timing adjustment value (TA value, abbreviated as TA as appropriate) applied to the candidate cell (which may be referred to as the target cell, target gNB, etc.) of the LTM transfer destination has been acquired by the RAR to the source cell of the LTM transfer source. In this embodiment, the RA execution unit 220 may constitute a transmission unit that transmits the acquired information.

[0067] The RA execution unit 220 may transmit the acquired information by at least one of an uplink physical channel, a control element of a medium access control layer, and a message of a radio resource control layer. For example, the RA execution unit 220 may transmit the acquired information by at least one of a PUCCH, a PUSCH, a MAC CE, and an RRC message.

[0068] When the RA execution unit 220 receives the RAR, the RA execution unit 220 may transmit an acknowledgement indicating that the timing adjustment value to be applied to the candidate cell of the LTM handover destination has been obtained by the RAR to the candidate cell by the LTM. The RA execution unit 220 may transmit the acknowledgement using at least one of a PUCCH, a PUSCH, a MAC CE, or an RRC message. In addition, the acknowledgement indicating that the RAR has been received may also be transmitted using at least one of a PUCCH, a PUSCH, a MAC CE, or an RRC message.

[0069] If the RAR cannot be received and the random access procedure fails, the RA execution unit 220 may transmit failure information indicating that the random access procedure has failed (random access failure) to the network. In this embodiment, the RA execution unit 220 may constitute a transmission unit that transmits the failure information.

[0070] Specifically, the RA executor 220 may transmit a random access report (RA report) including the failure information to the network.

[0071] The RA execution unit 220 may transmit an RA report including at least one of identification information of a candidate cell to be transferred by LTM, an index of an operating frequency band, and an index of an operating beam. Specifically, the RA report may include an LTM candidate cell ID and an operating frequency band of the cell. Furthermore, the index of an operating beam may be an index of a synchronization signal block (SS (Synchronization Signal) / PBCH (Physical Broadcast CHannel) Block)) or an index of a CSI-RS.

[0072] Furthermore, the RA execution unit 220 may transmit an RA report including the number of times the random access preamble has been transmitted. Specifically, the RA report may include the number of times the random access preamble has been transmitted in the target beam (SSB or CSI-RS) of the LTM candidate cell.

[0073] The RA executor 220 may transmit capability information (UE Capability Information) indicating capabilities related to transmission of the random access preamble to the network. In this embodiment, the RA executor 220 may constitute a transmitter that transmits the capability information. Specifically, the RA executor 220 may transmit UE Capability Information including whether or not PDCCH ordered RACH with RAR is supported.

[0074] The RA execution unit 220 may transmit UE Capability Information indicating a capability for obtaining a timing adjustment value to be applied to a candidate cell for handover by LTM. Specifically, the RA execution unit 220 may transmit UE Capability Information including support for obtaining TA included in the RAR in accordance with a PDCCH ordered RACH with RAR.

[0075] The RA execution unit 220 may transmit UE Capability Information including whether or not the RAR, that is, an acknowledgement indicating that the RAR according to the PDCCH ordered RACH with RAR has been received, is supported.

[0076] Furthermore, the RA execution unit 220 may transmit UE Capability Information including support or non-support of an acknowledgement indicating that the timing adjustment value to be applied to the candidate cell for handover by LTM has been acquired by the PDCCH ordered RACH with RAR.

[0077] The RA execution unit 220 may transmit UE Capability Information including support for transmitting failure information indicating that the RAR according to the PDCCH ordered RACH with RAR cannot be received and the random access procedure has failed. This failure may be referred to as a random access failure.

[0078] 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.

[0079] 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).

[0080] Furthermore, the handover execution unit 230 may execute early TA acquisition in order to execute RACH less HO.

[0081] 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).

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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).

[0086] In particular, in this embodiment, the control unit 240 may increase the value of the power ramping counter for the random access preamble based on the value of the random access preamble transmission counter according to the PDCCH ordered RACH with RAR, the candidate cell to which the LTM is to be transferred, and whether the synchronization signal block (SSB) or the reference signal for channel state information estimation (CSI-RS) has changed since the previous random access preamble transmission.

[0087] Specifically, the control unit 240 may increment the value of the PREAMBLE_POWER_RAMPING_COUNTER by "1" if the value of the PREAMBLE_TRANSMISSION_COUNTER and the state of the SSB or CSI-RS have not changed since the previous random access preamble transmission. In other words, the control unit 240 may increment the value of the power ramping counter if the candidate cell, synchronization signal block, or channel state information estimation reference signal has not changed since the previous random access preamble transmission. Note that the increment does not necessarily have to be "1."

[0088] When the control unit 240 has not acquired identification information (random access preamble ID) of the random access preamble according to the PDCCH ordered RACH with RAR, the control unit 240 may increment the value of a random access preamble transmission counter (PREAMBLE_TRANSMISSION_COUNTER). Specifically, when the control unit 240 cannot acquire from the RAR a random access preamble ID that matches the index (preamble index) of the random access preamble transmitted to the network via the RA execution unit 220, the control unit 240 may determine that reception of the RAR has failed and increment the value of PREAMBLE_TRANSMISSION_COUNTER by "1."

[0089] The control unit 240 may consider the random access procedure to be completed if a random access response (RAR) according to a PDCCH ordered RACH with RAR is triggered in a candidate cell to which LTM is to be transferred, and if the controller 240 acquires a random access preamble index (preamble index) and a corresponding random access preamble ID within a specific period.

[0090] Specifically, the control unit 240 may assume that the random access procedure is completed when the control unit 240 acquires the identification information (random access preamble ID) within a random access response reception time frame (ra-ResponseWindow). More specifically, the control unit 240 may assume that the random access procedure according to the PDCCH ordered RACH with RAR is completed when the control unit 240 receives an RAR including the random access preamble ID.

[0091] In addition, the control unit 240 may assume that the random access procedure is completed if the index of the random access preamble (preamble index) transmitted by the RA execution unit 220 matches the identification information of the random access preamble (random access preamble ID) included in the random access response. Here, "matching" may mean that the preamble index and the random access preamble ID match partially or entirely.

[0092] If the controller 240 does not receive a random access response to the random access preamble according to the PDCCH ordered RACH with RAR within a specific time (which may be referred to as ra-ResponseWindow) after transmitting the random access preamble, the controller 240 may increase the transmission power of the random access preamble and retransmit the random access preamble. Such an increase in transmission power may be referred to as power ramping.

[0093] <NW-trigger intra-CU LTM> Rel-18 supports NW-trigger intra-CU LTM, which allows handover between two cells within the same base station (CU) (see Figure 5).

[0094] <NW-trigger inter-CU LTM> Rel-19 is expected to support NW-triggered inter-CU LTM, which allows handover between two cells, for example, between different base stations (CUs) (see Figure 6).

[0095] Non-Patent Document 1 discusses / proposes, for example, the following regarding support for inter-CU Layer 2 Mobility (LTM) [RAN2, RAN3]. - Prioritize when CU is operating as MN when DC is not set Supports the case where NR-DC is configured as secondary priority, the CU acts as SN, and the MCG is not changed Supports the case where NR-DC is configured as secondary priority, the CU acts as MN, and the SCG is not changed or released. However, this does not apply if the LTM is set in both the MCG and SCG. Specifies support for subsequent LTM mobility procedures aimed at avoiding RRC setup between cell switches as per Rel-18 LTM Coordination with SA3 is required regarding security key handling. The Rel-18 intra-CU LTM procedure is considered a baseline for adding inter-CU support.

[0096] Furthermore, Rel-19 is expected to support UE-triggered LTM (conditional LTM), and Non-Patent Document 1, for example, discusses / proposes the following regarding conditional LTM [RAN2, RAN3, RAN1]. Specify UE evaluation conditions for triggering LTM Aims to support conditional LTM, including subsequent LTM Prioritize intra-CU LTM

[0097] <Discussion> In Rel-18, the NW-triggered intra-CU LTM supports PDCCH ordered RACH without RAR to perform LTM cell switch without RACH. It was also agreed that the NW-triggered inter-CU LTM under discussion in Rel-19 will also support PDCCH ordered RACH without RAR.

[0098] The procedure for PDCCH ordered RACH without RAR is as follows: 1. The network instructs the UE to use the RACH for a specific candidate cell via the PDCCH. 2. The UE transmits a PRACH to the candidate cell using the RA preamble indicated by the PDCCH. 3. The candidate cell forwards the TA obtained by the PRACH sent from the UE to the Source gNB / Source CU.

[0099] From the above, in the PDCCH ordered RACH without RAR, the UE cannot obtain the TA before cell switch.

[0100] However, in order to perform a RACH-less LTM cell switch using UE-triggered LTM (conditional LTM), which will be discussed in Rel-19, it is preferable that the UE acquires a TA before the cell switch.

[0101] The following may be ways in which the UE obtains a TA before an LTM cell switch: UE-based TA measurement ·PDCCH ordered RACH without RAR + TA transfer command (NW→UE) PDCCH ordered RACH with RAR

[0102] <Considerations> In Rel-19, for conditional LTM, both PDCCH ordered RACH without RAR (+ TA transfer command) and PDCCH ordered RACH with RAR may be supported.

[0103] In that case, it is expected that the UE will be notified whether or not there is an RAR, but this mechanism is an open issue.

[0104] It is also expected that the Source and Candidate (intra-CU: Source CU and Candidate DU, inter-CU: Source gNB and Candidate gNB) will have the same understanding of whether or not the PDCCH-ordered RACH has an RAR, but this mechanism is an open issue.

[0105] The present disclosure provides a technique for notifying whether or not an RAR exists.

[0106] <Embodiment> In UE-trigger LTM (Conditional LTM), any or all of the following may be supported for early UL sync (early TA acquisition): UE-based TA measurement ·PDCCH ordered RACH without RAR (+ TA transfer command) PDCCH ordered RACH with RAR

[0107] Fig. 7 is a diagram illustrating an example of a sequence of early TA acquisition (PDCCH ordered RACH without RAR). Fig. 8 is a diagram illustrating an example of a sequence of early TA acquisition (PDCCH ordered RACH with RAR).

[0108] As shown in Fig. 7, in the case of PDCCH ordered RACH without RAR, the RA procedure may be initiated by a command via the PDCCH. The PDCCH may include the information shown in Fig. 7. After receiving the PDCCH, the UE transmits a PDCCH ordered RACH (CFRA: Contention Free Random Access) to the Candidate DU. The Candidate DU acquires a TA and transfers it to the Source CU. The Source CU transfers the TA to the Source DU. The Source DU may transfer the TA to the UE using, for example, an LTM cell switch command. In the case of PDCCH ordered RACH without RAR, the random access response (RAR) can be omitted.

[0109] On the other hand, in the PDCCH ordered RACH with RAR, as shown in FIG. 8, the UE may obtain the TA value applied to the target cell by the RAR.

[0110] In UE-trigger LTM (Conditional LTM), if both PDCCH ordered RACH without RAR and PDCCH ordered RACH with RAR are supported, the NW may configure one of the following for the UE. PDCCH ordered RACH without RAR and PDCCH ordered RACH with RAR are not configured at the same time. PDCCH ordered RACH without RAR and PDCCH ordered RACH with RAR are configured simultaneously, but for one candidate cell, PDCCH ordered RACH without RAR and PDCCH ordered RACH with RAR are not configured simultaneously (e.g., Candidate cell #1: without RAR, Candidate cell #2: with RAR). PDCCH ordered RACH without RAR and PDCCH ordered RACH with RAR are simultaneously configured, and for one candidate cell, PDCCH ordered RACH without RAR and PDCCH ordered RACH with RAR are simultaneously configured (e.g., Candidate cell #1: without RAR+with RAR, Candidate cell #2: without RAR).

[0111] When PDCCH ordered RACH without RAR and PDCCH ordered RACH with RAR are not simultaneously configured for one candidate cell, the UE may determine whether RAR is present or absent by the following method. An indication is set in the LTM-Candidate in the LTM-Config (see Figure 9). This indication may also be set in the EarlyUL-SyncConfig in the LTM-Candidate (see Figures 10, 11, and 12). For example, if this indication is included or a specific value is indicated, the UE may recognize that the PDCCH is with RAR when receiving a PDCCH that orders RACH from the NW. For example, if this indication is not included or a specific value is indicated, the UE may recognize that it is without RAR when receiving a PDCCH that orders RACH from the NW. The recognition methods of with RAR and without RAR may be reversed. LTM-Config is an RRC message used to provide LTM configuration. LTM-Candidate is a message related to an LTM candidate configuration to be added or changed. EarlyUL-SyncConfig is a message used to configure random access resources for the early UL synchronization procedure. EarlyUL-SyncConfig may include a parameter pdcchOrderedRACH-withRAR for configuring a PDCCH ordered RACH with RAR. EarlyUL-SyncConfig may include a parameter pdcchOrderedRACH-WithOrWithoutRAR for configuring a PDCCH ordered RACH with RAR or a PDCCH ordered RACH without RAR. An indication is set in the PDCCH (ie, in DCI format 1_0) for the PDCCH ordered RACH (see FIG. 13). For example, if this indication is included or a specific value is indicated, the UE may recognize that the PDCCH is with RAR when receiving a PDCCH that orders RACH from the NW. For example, if this indication is not included or a specific value is indicated, the UE may recognize that it is without RAR when receiving a PDCCH that orders RACH from the NW. The recognition methods of with RAR and without RAR may be reversed. For example, if the CRC of DCI format 1_0 is scrambled by the C-RNTI and the "Frequency domain resource assignment" field is all ones, DCI format 1_0 is for a random access procedure initiated by a PDCCH order. DCI format 1_0 may include an RAR indicator (0 or 1 bit). If the UE is configured with the higher layer parameter EarlySyncConfig and supports both PDCCH ordered RACH with RAR and PDCCH ordered RACH without RAR for LTM, DCI format 1_0 may include an RAR indicator. This field may indicate whether the PDCCH ordered RACH is with or without RAR.

[0112] When PDCCH ordered RACH without RAR and PDCCH ordered RACH with RAR are simultaneously configured for one candidate cell, the UE may determine whether RAR is present or absent by the following method. · Set indication in PDCCH (i.e., in DCI format 1_0) for PDCCH ordered RACH. For example, if this indication is included or a specific value is indicated, the UE may recognize that the PDCCH is with RAR when it receives a PDCCH that orders RACH from the NW. For example, if this indication is not included or a specific value is indicated, the UE may recognize that it is without RAR when it receives a PDCCH for which RACH is ordered from the NW. The recognition methods for with RAR and without RAR may be reversed. The indication may be set to a DCI format other than DCI format 1_0 (for example, a new DCI format).

[0113] When simultaneously configuring PDCCH ordered RACH without RAR and PDCCH ordered RACH with RAR for one candidate cell, the following may be performed. Whether the PDCCH ordered RACH is performed without RAR or with RAR may be determined by the source CU or source DU in the case of intra-CU LTM, and may be determined by the source gNB in ​​the case of inter-CU LTM. In the case of intra-CU conditional LTM, the source CU may include in F1 signaling (e.g., UE context setup request, UE context modification request) a notification indicating whether the PDCCH ordered RACH for which a specific UE performs early TA acquisition is without RAR or with RAR (see Figure 14). In the case of Inter-CU conditional LTM, the source gNB may include in the Xn signaling (e.g., HO request) a notification indicating whether the PDCCH ordered RACH for which a specific UE performs early TA acquisition is without RAR or with RAR (see Figure 15).

[0114] <Summary of the embodiment> As described above, Rel-19 UE-trigger LTM (conditional LTM) provides a method for the UE to recognize which PDCCH ordered RACH without RAR and PDCCH ordered RACH with RAR to use when both are supported, and a method for the Candidate DU / Candidate gNB to recognize which one to use.

[0115] This disclosure is expected to realize simultaneous support of PDCCH-ordered RACH without RAR and PDCCH-ordered RACH with RAR in Rel-19 UE-trigger LTM (conditional LTM), provide flexibility in selecting the method for early UL sync (early TA acquisition), and enable network optimization and improved user experience by selecting the optimal method according to the network and UE conditions.

[0116] <Additional Notes> A radio communication unit (receiving unit) of the UE may receive the information. A control unit of the UE may determine, based on a command via a downlink control channel, one or both of a first transmission of a random access preamble that is premised on reception of a random access response and a second transmission of a random access preamble that is not premised on reception of a random access response.

[0117] The command via the downlink control channel may be a command for a PDCCH ordered RACH, the first transmission may be a PDCCH ordered RACH with an RAR, and the second transmission may be a PDCCH ordered RACH without an RAR.

[0118] The receiver of the UE may receive the information via higher layer signaling. For example, the receiver of the UE may receive the information via RRC signaling. In other words, the information may be included in an RRC (RRC message). For example, the information may be included in at least one of an LTM-Connig, an LTM-Candidate, and an EarlyUL-SyncConfg.

[0119] The receiver of the UE may receive the information via downlink control information. For example, the receiver of the UE may receive the information via DCI format 1_0 or another DCI format. In other words, the information may be included in a DCI format (DCI).

[0120] The control unit of the UE may determine one or both of the first transmission and the second transmission in terminal-initiated mobility control. The terminal-initiated mobility control may be, for example, LTM or Conditional LTM.

[0121] A control unit of the UE may perform terminal-initiated mobility control between two cells of the same base station or different base stations. A receiving unit of the UE may receive information determined by the source base station. The same base station may be a base station in NW-trigger intra-CU LTM, and the source base station may be a source CU or a source DU. A different base station may be a base station in NW-trigger inter-CU LTM, and the source base station may be a source gNB.

[0122] The present disclosure has been described above. Note that the division of items in the above description is not essential to the present disclosure, and items described in two or more items may be used in combination as needed, and items described in one item may be applied to items described in another item (unless they are inconsistent).

[0123] <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 hardware and / or software. Furthermore, the method for realizing each functional block is not particularly limited. That is, each functional block may be realized using a single device that is physically or logically coupled, or may be realized using two or more physically or logically separated devices that are connected directly or indirectly (for example, by wire, wirelessly, etc.) and these multiple devices. The functional block may also be realized by combining the single device or the multiple devices with software.

[0124] 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.

[0125] 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 wireless communication method of the present disclosure. Fig. 16 is a diagram showing an example of the hardware configuration of a base station and a terminal according to this embodiment. 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.

[0126] 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.

[0127] 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.

[0128] The processor 1001 controls the entire computer by running, for example, an operating system. The processor 1001 may be configured as 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 may be realized by the processor 1001.

[0129] 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 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 be transmitted from a network via a telecommunications line.

[0130] The memory 1002 is a computer-readable recording medium and may be configured, for example, by 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 executable programs (program codes), software modules, etc. for implementing a wireless communication method according to an embodiment of the present disclosure.

[0131] 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.

[0132] 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 and receiver may be realized by the communication device 1004.

[0133] 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).

[0134] 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.

[0135] 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.

[0136] <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.

[0137] <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.

[0138] <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.

[0139] <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.

[0140] <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 / output via multiple network nodes.

[0141] <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.

[0142] <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).

[0143] <Variations of 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).

[0144] 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.

[0145] <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.

[0146] 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.

[0147] <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.

[0148] 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.

[0149] <System, Network> As used in this disclosure, the terms "system" and "network" are used interchangeably.

[0150] <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.

[0151] 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.

[0152] <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.

[0153] 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.

[0154] 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.

[0155] <Mobile station> In this disclosure, the terms "Mobile Station (MS)," "user terminal," "User Equipment (UE)," "terminal," etc. may be used interchangeably.

[0156] 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.

[0157] <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.

[0158] 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 200 may be configured to have the functions of the base station 100 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.

[0159] Similarly, the term "terminal" in the present disclosure may be read as "base station." In this case, the base station 100 may be configured to have the functions of the terminal 200 described above.

[0160] Fig. 17 shows an example configuration of a vehicle 2001. As shown in Fig. 17, 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.

[0161] 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.

[0162] 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).

[0163] 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.

[0164] 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.

[0165] 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.

[0166] 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.

[0167] 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 29, which are provided in the vehicle 2001.

[0168] 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.

[0169] 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.

[0170] The communication module 2013 receives various information (traffic information, traffic signal information, vehicle distance information, etc.) transmitted from external devices and displays it on the information service unit 2012 provided in the vehicle 2001. The information service unit 2012 may also be called an output unit that outputs information (for example, outputs information to a device such as a display or speaker based on the PDSCH received by the communication module 2013 (or data / information decoded from the PDSCH)).

[0171] Furthermore, the communication module 2013 stores 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, axle 2009, sensors 2021 to 2029, and the like provided in the vehicle 2001.

[0172] <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.

[0173] 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.

[0174] <Reference signal> The reference signal may be abbreviated as RS (Reference Signal) or may be called a pilot depending on the applicable standard.

[0175] <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."

[0176] <"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.

[0177] <Means> In the configurations of each of the above devices, the "means" may be replaced with a "section", "circuit", "device", etc.

[0178] <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.

[0179] <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. The subframe may have a fixed time length (e.g., 1 ms) that does not depend on numerology.

[0180] 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, for example, at least one of 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.

[0181] 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.

[0182] 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.

[0183] 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.

[0184] 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.

[0185] 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.

[0186] 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.

[0187] 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.

[0188] 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.

[0189] 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.

[0190] 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.

[0191] 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.

[0192] 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.

[0193] 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.

[0194] 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.

[0195] 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.

[0196] 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."

[0197] 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.

[0198] <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.

[0199] <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.

[0200] <"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]

[0201] One aspect of the present disclosure is useful in wireless communication systems. [Explanation of symbols]

[0202] 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 receiving unit that receives information; a control unit that determines, based on a command via a downlink control channel, one or both of a first transmission of a random access preamble that is premised on reception of a random access response and a second transmission of a random access preamble that is not premised on reception of a random access response; and The control unit determines one or both of the first transmission and the second transmission based on the information. Terminal.

2. The receiving unit receives the information via higher layer signaling. The terminal according to claim 1 .

3. The receiving unit receives the information via downlink control information. The terminal according to claim 1 .

4. The control unit determines one or both of the first transmission and the second transmission in terminal-led mobility control.

5. The control unit performs terminal-initiated mobility control between two cells of the same base station or different base stations; The receiving unit receives the information determined by a source base station. The terminal according to claim 1 .

6. The device is Receive information and determining, based on a command via a downlink control channel, one or both of a first transmission of a random access preamble premised on reception of a random access response and a second transmission of a random access preamble not premised on reception of a random access response; determining one or both of the first transmission and the second transmission based on the information; Communication method.

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