Wireless base station and terminal

Abstract

This wireless base station performs early acquisition of a timing adjustment value of a target cell and a terminal that performs cell transition to the target cell without executing a random access procedure, and receives the timing adjustment value from the target cell. The wireless base station transmits, to the terminal, a control element of a medium access control layer including the received timing adjustment value.

Description

Wireless base station and terminal

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

[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) (see Non-Patent Document 1). L1 / L2 mobility, also known as Lower Layer Triggered Mobility (LTM), is a technology related to the mobility of terminals (User Equipment, UE) in Layer 1 or Layer 2, including the transition of UE to another cell (handover (HO)). HO by LTM is realized by lower layers such as the Medium Access Control layer (MAC).

[0004] In 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 met. In this way, by performing early TA acquisition before executing handover, LTM enables HO without a random access procedure (RA procedure) (RACH less HO).

[0005] In the case of RACH less HO, since a random access response (RAR) from the gNB is omitted, the UE cannot know the timing advance (TA) to be applied in the target cell. Therefore, a method (early TA acquisition) is specified in which the target cell (which may also be called a target gNB, a candidate cell, etc.) acquires the 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] 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

[0007] In the above-mentioned UE triggered LTM, during early TA acquisition, the target cell notifies the UE of the TA of its own cell (i.e., the target cell) using a cell switch command (MAC-CE), which is a control element (CE) of the medium access control layer (MAC).

[0008] However, in UE triggered LTM, switching to the target cell (handover) is triggered when the execution condition is satisfied. Therefore, if the Cell Switch Command MAC-CE is sent to the UE for the purpose of notifying the TA, the UE may become confused.

[0009] In addition, the existing TA command MAC CE for notifying TA is also specified, but the TA command MAC CE is for notifying the TA of the serving cell (source cell), and the serving cell cannot notify the TA of the target cell.

[0010] Therefore, the following disclosure has been made in consideration of the above circumstances, and aims to provide a radio base station and a terminal that can enable a UE to reliably acquire a TA of a target cell from a serving cell (source cell) when early TA acquisition is required to perform RACH less HO.

[0011] One aspect of the present disclosure is a radio base station (gNB100) that includes a control unit (control unit 140) that determines whether to activate or deactivate a cell transition execution condition for a terminal (UE200) that performs cell transition without instructions from a network when the execution condition is met, and a transmission unit (handover processing unit 120) that transmits an instruction to activate or deactivate the execution condition to the terminal.

[0012] One aspect of the present disclosure is a terminal (UE) that includes a control unit (control unit 240) that executes a cell transition without an instruction from a network when a condition for executing the cell transition is met, and a receiving unit (handover execution unit 230) that receives an instruction from the network to activate or deactivate the execution condition, and the control unit is a terminal (UE 200) that activates or deactivates the execution condition based on the instruction.

[0013] One aspect of the present disclosure is a radio base station (gNB100) comprising: a terminal (UE200) that performs cell transition to a target cell without performing a random access procedure; a control unit (control unit 140) that performs early acquisition of a timing adjustment value of the target cell; a receiving unit (TA setting unit 130) that receives the timing adjustment value from the target cell; and a transmitting unit (TA setting unit 130) that transmits to the terminal a control element of a medium access control layer including the timing adjustment value received by the receiving unit.

[0014] One aspect of the present disclosure is a terminal (UE) that includes a control unit (control unit 240) that performs cell transition to a target cell without performing a random access procedure, and a receiving unit (handover executing unit 230) that receives a control element of a medium access control layer including a timing adjustment value of the target cell from a serving cell, and the control unit is a terminal (UE) that performs cell transition to the target cell using the timing adjustment value received by the receiving unit.

[0015] FIG. 1 is a diagram illustrating an overall schematic configuration of a wireless communication system 10. FIG. 2 is a diagram illustrating an example of control using L1 / L2 mobility. FIG. 3 is a functional block diagram of a gNB 100. FIG. 4 is a functional block diagram of a UE 200. FIG. 5 is a diagram illustrating a first sequence example related to activation of an execution condition and notification of a TA value of a target cell. FIG. 6 is a diagram illustrating a second sequence example related to activation of an execution condition and notification of a TA value of a target cell. FIG. 7 is a diagram illustrating a third sequence example related to activation of an execution condition and notification of a TA value of a target cell. FIG. 8 is a diagram illustrating a fourth sequence example related to activation of an execution condition and notification of a TA value of a target cell. FIG. 9 is a diagram illustrating a fifth sequence example related to activation of an execution condition and notification of a TA value of a target cell. FIG. 10 is a diagram illustrating a sixth sequence example related to activation of an execution condition and notification of a TA value of a target cell. FIG. 11 is a diagram illustrating a sequence example related to a random access procedure and early TA acquisition. FIG. 12 is a diagram illustrating a first format example of a MAC CE according to operation example 2. Fig. 13 is a diagram showing a format example 2 of a MAC CE according to operation example 2. Fig. 14 is a diagram showing a format example 3 of a MAC CE according to operation example 2. Fig. 15 is a diagram showing a format example 4 of a MAC CE according to operation example 2. Fig. 16 is a diagram showing a format example 5 of a MAC CE according to operation example 2. Fig. 17 is a diagram showing a format example 6 of a MAC CE according to operation example 2. Fig. 18 is a diagram showing an example of the hardware configuration of the gNB 100 and the UE 200. Fig. 19 is a diagram showing an example of the configuration of a vehicle 2001.

[0016] Hereinafter, embodiments will be described with reference to the drawings. Note that the same or similar reference numerals are used to designate the same functions or configurations, and descriptions thereof will be omitted as appropriate.

[0017] (1) Overall Schematic Configuration of Wireless Communication System Fig. 1 is a diagram showing the overall schematic configuration of a wireless communication system 10 according to this embodiment. The wireless communication system 10 is a wireless communication system conforming to 5G New Radio (NR) and includes a Next Generation-Radio Access Network 20 (hereinafter, NG-RAN 20) and a terminal 200 (User Equipment 200, hereinafter, UE 200).

[0018] The wireless communication system 10 may be a wireless communication system conforming to a method called Beyond 5G, 5G Evolution, or 6G, or may include a wireless communication system conforming to a method called Long Term Evolution (LTE) or 4G. The wireless communication system 10 may support functions related to the Industrial Internet of Things (IIoT) and Ultra-Reliable and Low Latency Communications (URLLC).

[0019] The NG-RAN 20 includes a radio base station 100 (hereinafter, gNB 100). Note that the specific configuration of the radio communication system 10, including the number of gNBs (or eNBs, etc.) and UEs, is not limited to the example shown in FIG. 1 .

[0020] The gNB 100 may also employ a fronthaul (FH) interface defined by the Open Radio Access Network Alliance (O-RAN). The gNB 100 may include an O-RAN Distributed Unit (O-DU) and an O-RAN Radio Unit (O-RU). The gNB 100 can function as a type of NG-RAN node.

[0021] The NG-RAN 20 actually includes multiple NG-RAN nodes, specifically, gNBs (or ng-eNBs), and is connected to a 5G core network (5GC, not shown). The NG-RAN 20 and the 5GC may be simply referred to as a "network." The 5GC may introduce the concept of CUPS (Control and User Plane Separation), which clearly separates the functions of the user plane and the control plane.

[0022] 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.

[0023] The gNB100 and UE200 are capable of supporting Massive MIMO, which generates more directional beams by controlling radio signals transmitted from multiple antenna elements; Carrier Aggregation (CA), which aggregates and uses multiple component carriers (CCs); and Dual Connectivity (DC), which enables simultaneous communication between the UE and multiple NG-RAN nodes.

[0024] The type of DC may be Multi-RAT Dual Connectivity (MR-DC) that uses multiple radio access technologies, or NR-NR Dual Connectivity (NR-DC) that uses only NR. For example, one gNB may constitute a master node (MN), and one or more other gNBs may constitute secondary nodes (SNs).

[0025] 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.

[0026] 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).

[0027] In addition, in UE-initiated 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[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 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 existing events may include the following events (see 3GPP TS38.331). Note that the entering condition may be interpreted as a condition for determining whether or not to include a measurement report target, and the leaving condition may be interpreted as a condition for determining whether or not to exclude a measurement report target. At least one of the entering condition and the leaving condition may be applied as an execution condition in UE triggered LTM.

[0037] (i) Event A1 (Serving becomes better than threshold) Event A1 is an event in which the reception quality of the serving cell becomes better than a threshold. For example, the entering condition is Ms - Hys > Thresh, and the leaving condition is Ms + Hys < Thresh.

[0038] Here, Ms is the reception quality of the serving cell, Hys is a hysteresis parameter, and Thresh is a threshold value.

[0039] (ii) Event A2 (Serving Becomes Worse Than Threshold) Event A2 is an event in which the reception quality of the serving cell becomes worse than a threshold. For example, the entering condition is Ms + Hys < Thresh, and the leaving condition is Ms - Hys > Thresh.

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

[0041] (iii) Event A3 (Neighbor becomes offset better than SpCell) Event A3 is an event in which the reception quality of a neighboring cell becomes offset better than the reception quality of the serving cell. For example, the entering condition is Mn + Ofn + Ocn - Hys > Mp + Ofp + Ocp + Off, and the leaving condition is Mn + Ofn + Ocn + Hys < Mp + Ofp + Ocp + Off.

[0042] where Mn is the reception quality of the neighboring cell, Ofn is the offset specific to the measurement object, and Ocn is the offset specific to the cell. Mp is the reception quality of the serving cell, Ofp is the offset specific to the measurement object, and Ocp is the offset specific to the cell. Hys is the hysteresis parameter, and Off is the parameter used in Event A3.

[0043] (iv) Event A4 (Neighbor becomes better than threshold) Event A4 is an event in which the reception quality of a neighboring cell becomes better than a threshold. For example, the entering condition is Mn + Ofn + Ocn - Hys > Thresh, and the leaving condition is Mn + Ofn + Ocn + Hys < Thresh.

[0044] where Mn is the reception quality of the neighboring cell, Ofn is an offset specific to the measurement object, Ocn is an offset specific to the cell, Hys is a hysteresis parameter, and Thresh is a threshold value.

[0045] (v) Event A5 (SpCell becomes worse than threshold1 and neighbor becomes better than threshold2) Event A5 is an event in which the reception quality of the serving cell becomes worse than a threshold and the reception quality of the neighboring cell becomes better than a threshold. For example, the entering condition is Mp + Hys < Thresh1 and Mn + Ofn + Ocn - Hys > Thresh2, and the leaving condition is Mp - Hys > Thresh1 and Mn + Ofn + Ocn + Hys < Thresh2.

[0046] where Ms is the receiving quality of the serving cell, Hys is a hysteresis parameter, Thresh1 is a threshold, Mn is the receiving quality of the neighboring cell, Ofn is a measurement object-specific offset, and Ocn is a cell-specific offset, Hys is a hysteresis parameter, and Thresh2 is a threshold.

[0047] (vi) Event A6 (Neighbor becomes offset better than SCell) Event A6 is an event in which the reception quality of a neighboring cell becomes offset better than the reception quality of an SCell (Secondary Cell). For example, the entering condition is Mn + Ocn - Hys > Ms + Ocs + Off, and the leaving condition is Mn + Ocn + Hys < Ms + Ocs + Off.

[0048] In addition to the events described above, events related to RATs (Radio Access technologies) (e.g., B1 (Inter RAT neighbor becomes better than threshold), B2 (Serving becomes worse than threshold1 and inter RAT neighbor becomes better than threshold2)) may be included.

[0049] Here, Mn is the reception quality of the neighboring cell, Ocn is a cell-specific offset, Ms is the reception quality of the SCell, Ocs is a cell-specific offset, Hys is a hysteresis parameter, and Off is a parameter used in Event A6.

[0050] In this embodiment, the channels include a control channel and a data channel, such as a physical downlink control channel (PDCCH), a physical uplink control channel (PUCCH), a physical random access channel (PRACH), and a physical broadcast channel (PBCH).

[0051] The data channels include a physical downlink shared channel (PDSCH) and a physical uplink shared channel (PUSCH).

[0052] 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.

[0053] (2) Functional Block Configuration of Wireless Communication System Next, the functional block configuration of the wireless communication system 10 will be described. Specifically, the functional block 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.

[0054] (2.1) gNB100 As shown in FIG. 3, the gNB100 includes a radio communication unit 110, a handover processing unit 120, a TA setting unit 130, and a control unit 140.

[0055] The wireless communication unit 110 transmits downlink signals (DL signals) conforming to NR, and also receives uplink signals (UL signals) conforming to NR.

[0056] The TCI state (transmission configuration indication state) can provide information on antenna ports that are substantially co-located (quasi-collocated: QCL) with the antenna ports of the PDCCH. If the UE 200 has a specific control resource set (CORESET) that is spatially co-located with a specific CSI-RS, the UE 200 can determine which beam is appropriate when attempting to receive the PDCCH using the CORESET. Note that the QCL / TCI state / beam may be interpreted interchangeably.

[0057] 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).

[0058] Handover (HO) may also be called cell transition, cell selection, or cell reselection. Handover may be cell-based, but may also involve changing (switching) some of the beams to another cell.

[0059] The serving cell may be simply interpreted as the cell to which the UE 200 is connected, or more precisely, in the case of an RRC_CONNECTED UE without carrier aggregation (CA), there is only one serving cell that constitutes the primary cell. In the case of an RRC_CONNECTED UE configured with CA, the serving cell may be interpreted as indicating a set of one or more cells including the primary cell and all secondary cells.

[0060] 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 a conditional RRC reconfiguration of the selected cell to reconnect without transmitting an RRC Restablishment Request to the candidate target cell.

[0061] The handover processing unit 120 may transmit an instruction to activate or deactivate a specific execution condition to the terminal. In this embodiment, the handover processing unit 120 may constitute a transmission unit that transmits an instruction to activate or deactivate an execution condition.

[0062] Specifically, when RACH less HO is applied, such as UE triggered LTM (which may be interpreted as a case where early TA acquisition (early synchronization) is applied), the handover processing unit 120 can instruct the UE 200 to activate / deactivate the execution condition for RACH less HO.

[0063] The layer in which the activation / deactivation instruction of the execution condition is executed is not particularly limited, and may be a MAC control element (MAC CE), a physical layer (PHY) (e.g., PDCCH (DCI)), or a message of a higher layer (RRC).

[0064] The TA setting unit 130 sets a timing advance (TA), etc. Specifically, the TA setting unit 130 can set a TA value to be applied to the own cell, etc. (a cell or beam formed by the gNB 100).

[0065] Furthermore, the TA setting unit 130 can transmit and receive information on a TA value to be applied to a target cell to which the UE 200 is to be transferred. Specifically, the TA setting unit 130 can receive the TA value of the target cell from the target cell. In this embodiment, the TA setting unit 130 may constitute a receiving unit that receives a timing adjustment value from the target cell.

[0066] The timing at which the TA setting unit 130 receives the TA value of the target cell is not particularly limited, but it is preferable that the TA value be received after the UE 200 executes a random access procedure with the target cell.

[0067] The TA setting unit 130 can transmit a medium access control layer control element (MAC CE) including the timing adjustment value of the target cell received from the target cell to the UE 200. In this embodiment, the TA setting unit 130 may configure a transmission unit that transmits the medium access control layer control element including the timing adjustment value of the target cell.

[0068] For example, the TA setting unit 130 may transmit to the UE 200 a MAC CE including the TA value of the target cell included in the TA information transfer transmitted from the target cell.

[0069] The TA setting unit 130 may transmit a MAC CE including the TA value and an execution condition for cell transition, i.e., an instruction to activate the execution condition, to the UE 200. The TA setting unit 130 may transmit a MAC CE to the UE 200, further including resources of a random access channel (RACH) associated with a synchronization signal block (SSB: (SS (Synchronization Signal) / PBCH (Physical Broadcast CHannel) Block)).

[0070] 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).

[0071] 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.

[0072] 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.

[0073] Furthermore, for UE 200 that executes cell transfer regardless of an instruction from the network when an execution condition such as UE triggered LTM is satisfied, control unit 140 can determine whether to activate or deactivate the execution condition.

[0074] Specifically, the control unit 140 can set activation / deactivation for some or all of the multiple execution conditions. The deactivation state of an execution condition may be defined as the UE 200 not performing monitoring for the set execution condition. The activation state of an execution condition may be defined as the UE performing monitoring for the set execution condition. In a broad sense, the deactivation state of an execution condition may be interpreted as a state in which the UE 200 does not perform any operation using the execution condition, and the activation state of an execution condition may be interpreted as a state in which the UE 200 can perform operations using the execution condition without any particular restrictions.

[0075] Furthermore, an execution condition may be assigned an identification (ID) capable of identifying a beam transmitted from a radio base station (gNB). The ID may be assigned to the execution condition itself, and it is desirable that the ID be capable of identifying the execution condition at the beam level. The control unit 140 may use the ID to determine whether to activate or deactivate the execution condition on a beam-by-beam basis. The ID may be transmitted to the UE 200, and the activation or deactivation of a specific execution condition may be instructed based on the ID.

[0076] When the control unit 140 first sets an execution condition for the UE 200, the control unit 140 may determine to deactivate the execution condition. That is, it is desirable that the execution condition be in a deactivation state at an initial stage. The control unit 140 may activate an execution condition in a deactivation state at a predetermined timing.

[0077] Furthermore, the control unit 140 may separately configure a target cell (candidate cell config) as a transfer destination and configure an execution condition for the UE 200. For example, the control unit 140 may configure the candidate cell config first, and then configure the execution condition for the UE 200 after early TA acquisition. Note that if the candidate cell config is configured before the execution condition, the candidate cell config may be configured after early TA acquisition.

[0078] (2.2) UE 200 As shown in FIG. 4, the UE 200 includes a radio communication unit 210, a measurement reporting unit 220, a handover execution unit 230, and a control unit 240.

[0079] 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.

[0080] The measurement reporting unit 220 performs measurement reporting based on the configuration (measurement configuration) of quality measurements of the serving cell and neighboring cells. Specifically, the measurement reporting unit 220 may perform measurement reporting based on the measurement configuration in Layer 3, or may perform measurement reporting based on the measurement configuration in Layer 1 and / or Layer 2.

[0081] The measurement reporting unit 220 can measure the quality of the serving cell of the UE 200 and neighboring cells of the serving cell and report the measurement results (Measurement Report) to the network. The measurement reporting unit 220 can perform measurement reporting of the source cell and the target cell during handover.

[0082] The quality to be measured may be, for example, the quality included in the Measurement Report specified in 3GPP TS38.331 (e.g., Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ)).

[0083] 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.

[0084] The handover execution unit 230 can also execute processes related to normal handover (legacy handover), handover according to L1 / L2 Mobility (LTM), conditional handover (CHO), and DAPS handover. The handover execution unit 230 may also support RACH-less HO. LTM may include network-triggered LTM and UE-triggered LTM.

[0085] 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 a reference signal (RS), specifically, the value of RSRP, RSRQ, or SINR.

[0086] Furthermore, the handover execution unit 230 may execute handover based on not only L3 Mobility but also L1 / L2 Mobility (LTM). 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.

[0087] The type of the command is not particularly limited, and may be, for example, an L1 / L2 Mobility command (e.g., MAC). The L1 / L2 Mobility command may be replaced with another command of the RRC layer.

[0088] The handover execution unit 230 may receive an instruction to activate or deactivate the execution condition from the network. In this embodiment, the handover execution unit 230 may be configured as a receiver that receives an instruction to activate or deactivate the execution condition from the network.

[0089] Specifically, the handover execution unit 230 may receive a MAC CE from the source cell that includes an instruction for activation / deactivation of an execution condition. The instruction may be directed to a specific execution condition, or to some or all of the execution conditions.

[0090] Furthermore, the handover executor 230 may receive a MAC CE including the TA value of the target cell from the serving cell. In this embodiment, the handover executor 230 may configure a receiver that receives a timing adjustment value of the target cell. Specifically, the handover executor 230 may receive a MAC CE including the TA value of the target cell from the source cell.

[0091] The timing of receiving the MAC CE is not particularly limited, but the handover executing unit 230 may receive the MAC CE after the UE 200 has executed a random access procedure with the target cell.

[0092] 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.

[0093] The control unit 240 can also perform L1 / L2 Mobility (LTM), i.e., mobility control of at least one of layer 1 and layer 2. Mobility control by L1 / L2 Mobility may include quality measurement of service areas and neighboring cells in layer 1 or layer 2, setting of destination candidate cells, cell reselection (transition), handover, etc. In this way, the control unit 240 can perform handover in accordance with mobility control by a lower layer.

[0094] Furthermore, the control unit 240 can select a cell as a transfer destination when L1 / L2 Mobility (LTM) fails (LTM failure). Note that an LTM failure may include a failure in a measurement or transfer (handover) procedure associated with cell transfer by LTM.

[0095] In this embodiment, the control unit 240 executes cell transition regardless of an instruction from the network when the execution condition of the cell transition is satisfied. Such cell transition may be interpreted as UE triggered LTM, or may be interpreted as targeting RACH less HO (which may include early TA acquisition) without being limited to LTM.

[0096] The control unit 240 may activate or deactivate an execution condition based on an instruction to activate or deactivate the execution condition received by the handover execution unit 230.

[0097] Furthermore, the control unit 240 may activate the execution condition when the handover execution unit 230 acquires the TA value of the target cell of the transfer destination. Alternatively, the control unit 240 may activate the execution condition when the acquisition of the TA value and the activation of the transmission configuration indication state (TCI state) are completed.

[0098] The control unit 240 may execute cell transition to the target cell using the TA value of the target cell received by the handover execution unit 230. Specifically, the control unit 240 may execute UL synchronization establishment and the like using the TA value of the target cell.

[0099] (3) Operation of the Wireless Communication System Next, a description will be given of the operation of the wireless communication system 10. Specifically, a description will be given of the operation related to RACH-less HO in accordance with UE triggered LTM.

[0100] (3.1) Operation Example 1 (3.1.1) Assumptions and Issues As described above, in the wireless communication system 10, UE triggered LTM is applied, and the UE can perform RACH less HO.

[0101] In UE triggered LTM, when an execution condition and a candidate cell configuration are simultaneously set by the RRC layer (message), the UE starts monitoring the execution condition without delay. Then, when the monitored execution condition is satisfied, the UE promptly performs RACH less HO, i.e., LTM cell switch.

[0102] However, in the case of RACH less HO according to UE triggered LTM, the UE needs to perform early synchronization (early TA acquisition) with the target cell (target gNB) in advance. If the execution condition is satisfied before the TA acquisition of the target cell is completed by early TA acquisition, the UE does not have the TA information of the target cell, and therefore, UL synchronization with the target cell cannot be established, which may result in LTM failure.

[0103] The procedure for early TA acquisition is roughly as follows:

[0104] (i) The gNB transmits a PDCCH to the UE instructing it to perform RACH with the candidate cell in advance.

[0105] (ii) According to the instruction, the UE performs RACH with the candidate cell (PDCCH ordered RACH).

[0106] The PDCCH ordered RACH in (ii) may be defined as a RACH without an RAR (RA response). In a conventional (legacy) RACH, the gNB can notify the UE of the TA by the RAR, but the LTM PDCCH ordered RACH does not have an RAR, so TA cannot be obtained.

[0107] (3.1.2) Operational Example An operational example that can solve the above-mentioned problem will be described below. In this operational example, activation / deactivation may be applied to the execution condition. As described above, the deactivation state of the execution condition may be defined as the UE 200 not performing monitoring for the set execution condition. Also, the activation state of the execution condition may be defined as the UE performing monitoring for the set execution condition.

[0108] An ID may be assigned to the execution condition. This ID may be the measurement identification information (measId) that manages the event-triggered L1 measurement, or may be a separate ID associated with the measId. As mentioned above, the ID may be assigned to the execution condition itself, and it is desirable to make it possible to identify the beam-level execution condition.

[0109] When the network (gNB) first sets an execution condition for UE200 (which may be set via the RRC layer), the execution condition may be set to the deactivation state.

[0110] In addition, the execution condition may automatically transition to the activation state when the UE completes acquiring the TA of the target cell (candidate cell), or when the UE completes both TA acquisition of the target cell and TCI state activation.

[0111] The source cell (source gNB) may send an instruction to activate the execution condition to the UE. The instruction may be implemented by MAC CE or by the physical layer (PHY) (e.g., PDCCH (DCI)). Alternatively, a message from a higher layer (RRC) may be used. Note that the target cell may also be allowed to send the instruction, rather than the source cell.

[0112] In addition, as for the timing of transmitting the instruction, for example, in early TA acquisition, after the UE receives the PDCCH ordered RACH instruction (see FIG. 11), the UE executes RACH with the target cell, and the target cell may transmit the TA value for its own cell to the source cell. The source cell may transmit an instruction to activate the execution condition to the UE in response to acquiring the TA value from the target cell.

[0113] Furthermore, the source cell may separately configure a target cell (candidate cell config) as a transfer destination and configure an execution condition for the UE 200. For example, the source cell may configure the candidate cell config first, and then configure the execution condition for the UE 200 after early TA acquisition.

[0114] In this way, when the network transmits the candidate cell config and the execution condition separately to the UE, the execution condition may be included in the RRC Reconfiguration message, or the execution condition (operating at the MAC layer) may be included in the MAC CE (which may be new).

[0115] In addition, if the UE is configured with UE-based TA measurement (UE measured TA) by the network, the UE may autonomously activate the execution condition after completing the UE measured TA measurement.

[0116] When the UE completes TA acquisition of a target cell (candidate cell) through UE-based TA measurement, the UE may notify the network of the completion of TA acquisition. The notification may be performed using MAC CE, PUCCH, or PUSCH. Note that the target cell may be interpreted as the same as the candidate cell, or may be interpreted as one or more cells selected from multiple candidate cells.

[0117] Fig. 5 shows a first example of a sequence relating to the activation of the execution condition and the notification of the TA value of the target cell. As shown in Fig. 5, the TA value acquired by the network may be notified to the UE using a new MAC CE, and activation of the execution condition may be instructed.

[0118] Specifically, when a source cell (source gNB) receives a TA information transfer from a target cell (target gNB), it may send a MAC CE to the UE that includes the TA value of the target cell included in the TA information transfer and an activation instruction for the execution condition.

[0119] The UE may start monitoring the execution condition based on the MAC CE, and if the execution condition is satisfied, apply the cell configuration of the target cell.

[0120] Fig. 6 shows a second example of a sequence relating to the activation of the execution condition and the notification of the TA value of the target cell. As shown in Fig. 6, the TA value acquired by the network may be notified to the UE using a new MAC CE, and activation of the execution condition may be instructed (similar to Example 1). In Example 2, the RRC Reconfiguration includes only the candidate cell config, and the MAC CE transmitted after early TA acquisition includes the setting of the execution condition.

[0121] Fig. 7 shows a third example of a sequence relating to activation of an execution condition and notification of a TA value of a target cell. As shown in Fig. 7, a TA value acquired by the network may be notified to a UE using a new MAC CE, and the setting of the execution condition may be notified using RRC Reconfiguration.

[0122] Figure 8 shows a fourth example of a sequence relating to activation of an execution condition and notification of a TA value of a target cell. As shown in Figure 8, the UE may perform UE-based TA measurement (automatic activation of the execution condition is not applied), and the source cell may instruct activation of the execution condition using a new MAC CE.

[0123] 9 shows a fifth example of a sequence relating to activation of an execution condition and notification of a TA value of a target cell. As shown in FIG. 9, the UE performs UE-based TA measurement (automatic activation of the execution condition is not applied), and the source cell may notify the setting of the execution condition or instruct activation of the execution condition using a new MAC CE.

[0124] 10 shows a sixth example of a sequence relating to activation of an execution condition and notification of a TA value of a target cell. As shown in FIG. 10, a UE may perform UE-based TA measurement and automatically activate an execution condition.

[0125] (3.2) Operation Example 2 (3.2.1) Assumptions and Issues As described above, RACH-less HO is premised on the fact that the TA value of the target cell is acquired in advance by early TA acquisition.

[0126] However, in the existing 3GPP specifications (Release 18), in the case of RACH-less HO according to UE-triggered LTM, the TA value is included in the cell switch command (Cell Switch Command MAC-CE), and there is no MAC CE that can notify the TA value of the target cell without cell switch.

[0127] It is possible to reuse the Cell Switch Command MAC-CE. However, since RACH less HO according to UE triggered LTM triggers cell switching (cell transition) when the execution condition is satisfied, simply reusing the MAC CE to notify the TA value of the target cell may confuse the UE.

[0128] Although the existing TA command MAC CE for notifying TA is also specified, the TA command MAC CE is for notifying the TA of the serving cell (source cell), and the serving cell cannot notify the TA of the target cell.

[0129] (3.2.2) Example of Operation An example of operation that can solve the above-mentioned problem will be described below. In this example of operation, a new MAC CE that notifies the TA value of the target cell may be used.

[0130] 11 shows an example sequence of a random access procedure and early TA acquisition. As shown in FIG. 11, when a UE receives a PDCCH ordered RACH indication from a source cell (source gNB), the UE may perform a contention-free random access procedure (CFRA) with a target cell. The target cell (target gNB) may acquire a TA value for its own cell and transmit the acquired TA value to the source cell.

[0131] When the source cell receives the TA value from the target cell, the source cell may send a MAC CE including the TA value to the UE.

[0132] The MAC CE may include both the TA value of the target cell and an activation instruction for the execution condition. Alternatively, the MAC CE may include the TA value of the target cell, an activation instruction for the execution condition, and a RACH resource associated with the SSB.

[0133] Fig. 12 shows format example 1 of a MAC CE according to operation example 2. As shown in Fig. 12, the MAC CE may include a field indicating a TA value (Timing Advance Command) of the target cell.

[0134] When the UE receives the MAC CE, the UE may activate the execution condition associated with the cell. That is, the reception of the MAC CE by the UE may mean that the execution condition associated with the cell is automatically activated. Alternatively, it may mean that the execution conditions associated with all candidate cells are automatically activated. Note that other fields of the MAC CE may be the same as those of the Cell Switch Command MAC-CE in 3GPP Release 18 (the same applies below).

[0135] Fig. 13 shows format example 2 of MAC CE according to operation example 2. The following mainly describes the parts that are different from format example 1 shown in Fig. 12. Field "A" (underlined) may mean that the execution condition associated with the cell is activated.

[0136] 14 shows a format example 3 of a MAC CE according to the operation example 2. The field “Execution condition” (underlined) may mean activating the execution condition associated with the candidate target cell.

[0137] The content of the execution condition may be set in advance by signaling such as RRC. The field "Execution condition" may be identification information (execution condition ID) that associates the execution condition set in advance by RRC, or may be measId. The measId may manage event-triggered L1 measurement reporting. The event-triggered L1 measurement reporting is a measurement report triggered by an event in a lower layer, and the field "Execution condition" may be any ID that can identify the execution condition.

[0138] 15 shows a format example 4 of a MAC CE according to the operation example 2. The field "A" (underlined) may mean that the execution condition associated with the cell is activated. The MAC CE may consist of only one octet.

[0139] 16 shows a format example 5 of a MAC CE according to the operation example 2. The field "A" (underlined) may mean that the execution conditions associated with all candidate cells are activated. The MAC CE may consist of only one octet.

[0140] 17 shows a format example 6 of a MAC CE according to the operation example 2. The field "Ci" (C1 to C7) may indicate the activation / deactivation state of the execution condition associated with the LTM candidate cell (corresponding to ltm-candidateId minus 1). "1" may indicate that the execution condition is in the activated state, and "0" may indicate that the execution condition is in the deactivated state. Note that "1" and "0" may indicate the opposite states.

[0141] According to the above-described operation example 1, in RACH less HO according to UE triggered LTM, activation / deactivation of an execution condition can be appropriately configured. Specifically, the MAC CE that configures the activation / deactivation of an execution condition for a UE can control the activation / deactivation of a specific execution condition at the initiative of the network.

[0142] Therefore, even when the UE performs RACH less HO, the UE can avoid a state in which the execution condition is satisfied when the UE does not have the target cell TA. This can eliminate the possibility that the UE cannot establish UL synchronization with the target cell and the LTM (cell transition) fails because the UE does not have the target cell TA.

[0143] Furthermore, according to the above-described operation example 2, a new MAC CE is used to notify the TA value of the target cell. Therefore, the source cell (source gNB) can notify the UE of the TA of the target cell (candidate cell) after early TA acquisition. In other words, when early TA acquisition is required to perform RACH less HO, the UE can reliably acquire the TA of the target cell from the serving cell (source cell). This makes it possible to more reliably perform RACH less HO according to UE triggered LTM without performing UE-based TA measurement.

[0144] (4) Other Embodiments Although the embodiments have been described above, it will be obvious to those skilled in the art that the present invention is not limited to the description of the embodiments, and that various modifications and improvements are possible.

[0145] For example, in the above-described embodiment, RACH less HO is described assuming UE triggered LTM, but as described above, similar operations may be applied to other handovers (e.g., CHO) without being limited to LTM when RACH is omitted. More specifically, similar operations may be applied to RACH less mobility using early TA acquisition (early synchronization).

[0146] Also, in the above description, configure, activate, update, indicate, enable, specify, and select may be interchangeable. Similarly, link, associate, correspond, and map may be interchangeable, and allocate, assign, monitor, and map may be interchangeable.

[0147] Furthermore, specific, dedicated, UE-specific, and UE-dedicated may be interchangeable. Similarly, common, shared, group-common, UE-common, and UE-shared may be interchangeable.

[0148] In this disclosure, terms such as "precoding," "precoder," "weight (precoding weight)," "Quasi-Co-Location (QCL)," "Transmission Configuration Indication state (TCI state)," "spatial relation," "spatial domain filter," "transmit power," "phase rotation," "antenna port," "antenna port group," "layer," "number of layers," "rank," "resource," "resource set," "resource group," "beam," "beam width," "beam angle," "antenna," "antenna element," "panel," etc. may be used interchangeably.

[0149] The block diagram ( FIG. 3 ) used to explain the above-described embodiment shows functional blocks. These functional blocks (components) are realized by any combination of hardware and / or software. Furthermore, the method for realizing each functional block is not particularly limited. That is, each functional block may be realized using a single device that is physically or logically coupled, or may be realized using two or more physically or logically separated devices that are connected directly or indirectly (e.g., via wire, wireless, etc.) and these multiple devices. The functional block may be realized by combining the single device or multiple devices with software.

[0150] Functions include, but are not limited to, judgment, determination, judgment, calculation, computation, processing, derivation, investigation, search, confirmation, reception, transmission, output, access, resolution, selection, selection, establishment, comparison, assumption, expectation, consideration, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating, mapping, and assignment. For example, a functional block (component) that performs transmission is called a transmitting unit or transmitter. As mentioned above, there are no particular limitations on how each is implemented.

[0151] Furthermore, the above-described gNB100 and UE200 (the devices) may function as a computer that performs processing of the wireless communication method of the present disclosure. Figure 18 is a diagram showing an example of the hardware configuration of the devices. As shown in Figure 18, the devices may be configured as a computer 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.

[0152] In the following description, the term "apparatus" can be interpreted as a circuit, a device, a unit, etc. The hardware configuration of the apparatus may be configured to include one or more of the apparatuses shown in the drawings, or may be configured to exclude some of the apparatuses.

[0153] Each functional block of the device (see FIG. 3) is realized by any hardware element of the computer device or a combination of the hardware elements.

[0154] In addition, each function of the device is realized by loading specified software (programs) onto hardware such as processor 1001 and memory 1002, causing processor 1001 to perform calculations, control communication via communication device 1004, and control at least one of reading and writing data in memory 1002 and storage 1003.

[0155] The processor 1001 controls the entire computer by running, for example, an operating system, and may be configured as a central processing unit (CPU) including an interface with peripheral devices, a control unit, an arithmetic unit, and registers.

[0156] The processor 1001 also reads programs (program codes), software modules, data, etc. from at least one of the storage 1003 and the communication device 1004 into the memory 1002 and executes various processes in accordance with these. The programs used are those that cause a computer to execute at least some of the operations described in the above-described embodiments. Furthermore, the various processes described above may be executed by a single processor 1001, or may be executed simultaneously or sequentially by two or more processors 1001. The processor 1001 may be implemented by one or more chips. The programs may be transmitted from a network via a telecommunications line.

[0157] The memory 1002 is a computer-readable recording medium and may be configured by at least one of, for example, a read-only memory (ROM), an erasable programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM), a random access memory (RAM), etc. The memory 1002 may also be called a register, a cache, a main memory (primary storage device), etc. The memory 1002 may store a program (program code), a software module, etc., capable of executing a method according to an embodiment of the present disclosure.

[0158] Storage 1003 is a computer-readable recording medium, and may be, for example, at least one of an optical disk such as a Compact Disc ROM (CD-ROM), a hard disk drive, a flexible disk, a magneto-optical disk (e.g., a compact disk, a digital versatile disk, a Blu-ray disc), a smart card, a flash memory (e.g., a card, a stick, a key drive), a floppy disk, a magnetic strip, etc. Storage 1003 may also be referred to as an auxiliary storage device. The above-mentioned recording medium may be, for example, a database, a server, or other suitable medium including at least one of memory 1002 and storage 1003.

[0159] The communication device 1004 is hardware (transmission / reception device) for communicating between computers via at least one of a wired network and a wireless network, and is also called, for example, a network device, a network controller, a network card, or a communication module.

[0160] The communication device 1004 may be configured to include a high-frequency switch, a duplexer, a filter, a frequency synthesizer, etc. to realize, for example, at least one of Frequency Division Duplex (FDD) and Time Division Duplex (TDD).

[0161] The input device 1005 is an input device (e.g., a keyboard, a mouse, a microphone, a switch, a button, a sensor, etc.) that receives input from the outside. The output device 1006 is an output device (e.g., a display, a speaker, an LED lamp, etc.) that outputs to the outside. Note that the input device 1005 and the output device 1006 may be integrated into one device (e.g., a touch panel).

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

[0164] Furthermore, the notification of information is not limited to the aspects / embodiments described in the present disclosure, and may be performed using other methods. For example, the notification of information may be performed by physical layer signaling (e.g., Downlink Control Information (DCI), Uplink Control Information (UCI)), higher layer signaling (e.g., RRC signaling, Medium Access Control (MAC) signaling, broadcast information (Master Information Block (MIB), System Information Block (SIB))), other signals, or a combination thereof. Furthermore, the RRC signaling may be referred to as an RRC message, and may be, for example, an RRC Connection Setup message, an RRC Connection Reconfiguration message, or the like.

[0165] Each aspect / embodiment described in the present disclosure may be applied to at least one of a system using Long Term Evolution (LTE), LTE-Advanced (LTE-A), SUPER 3G, IMT-Advanced, a 4th generation mobile communication system (4G), a 5th generation mobile communication system (5G), a 6th generation mobile communication system (6G), an xth generation mobile communication system (xG) (where x is, for example, an integer or a decimal), Future Radio Access (FRA), New Radio (NR), W-CDMA (registered trademark), GSM (registered trademark), CDMA2000, Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi (registered trademark)), IEEE 802.16 (WiMAX (registered trademark)), IEEE 802.20, Ultra-WideBand (UWB), Bluetooth (registered trademark), or other suitable system, and a next-generation system extended based on these. Furthermore, a combination of multiple systems (e.g., a combination of at least one of LTE and LTE-A with 5G) may also be applied.

[0166] 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.

[0167] In the present disclosure, a specific operation described as being performed by a base station may also be performed by its upper node in some cases. In a network consisting of one or more network nodes having a base station, it is clear that various operations performed for communication with a terminal may be performed by at least one of the base station and another network node other than the base station (e.g., MME or S-GW, etc., but are not limited to these). Although the above example illustrates a case where there is one other network node other than the base station, a combination of multiple other network nodes (e.g., MME and S-GW) may also be used.

[0168] Information, signals (information, etc.) may be output from a higher layer (or a lower layer) to a lower layer (or a higher layer), or may be input and output via multiple network nodes.

[0169] The input and output information may be stored in a specific location (for example, a memory) or may be managed using a management table. The input and output information may be overwritten, updated, or added. The output information may be deleted. The input information may be transmitted to another device.

[0170] 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).

[0171] The aspects / embodiments described in this disclosure may be used alone, in combination, or switched depending on the implementation. Notification of predetermined information (e.g., notification that "X is true") is not limited to explicit notification, but may be implicit (e.g., not notifying the predetermined information).

[0172] 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.

[0173] 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.

[0174] 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.

[0175] Note that terms described in this disclosure and terms necessary for understanding this disclosure may be replaced with terms having the same or similar meanings. For example, at least one of a channel and a symbol may be a signal (signaling). Furthermore, a signal may be a message. Furthermore, a component carrier (CC) may be called a carrier frequency, a cell, a frequency carrier, etc.

[0176] As used in this disclosure, the terms "system" and "network" are used interchangeably.

[0177] 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.

[0178] 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.

[0179] 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.

[0180] A base station can accommodate one or more (e.g., three) cells (also called sectors). When a base station accommodates multiple cells, the overall coverage area of ​​the base station can be divided into multiple smaller areas, and each smaller area can be provided with communication services by a base station subsystem (e.g., a small indoor base station (Remote Radio Head: RRH)).

[0181] The terms "cell" or "sector" refer to part or all of the coverage area of ​​a base station and / or base station subsystem that provides communication services within that coverage area.

[0182] 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.

[0183] In this disclosure, the terms "Mobile Station (MS)," "user terminal," "User Equipment (UE)," "terminal," etc. may be used interchangeably.

[0184] 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.

[0185] 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.

[0186] Furthermore, a base station in the present disclosure may be read as a mobile station (user terminal, the same applies hereinafter). For example, the aspects / embodiments of the present disclosure may be applied to a configuration in which communication between a base station and a mobile station is replaced with communication between multiple mobile stations (which may be called, for example, Device-to-Device (D2D) or Vehicle-to-Everything (V2X)). In this case, the mobile station may be configured to have the functions of a base station. Furthermore, terms such as "uplink" and "downlink" may be read as terms corresponding to terminal-to-terminal communication (for example, "side"). For example, terms such as an uplink channel and a downlink channel may be read as a side channel (or sidelink).

[0187] Similarly, a mobile station in the present disclosure may be interpreted as a base station, in which case the base station may have the functions of a mobile station.

[0188] A radio frame may be composed of one or more frames in the time domain. Each of the one or more frames in the time domain may be called a subframe. A subframe may further be composed of one or more slots in the time domain. A subframe may have a fixed time length (e.g., 1 ms) that is independent of numerology.

[0189] Numerology may be communication parameters that apply to the transmission and / or reception of a signal or channel, such as subcarrier spacing (SCS), bandwidth, symbol length, cyclic prefix length, transmission time interval (TTI), number of symbols per TTI, radio frame structure, specific filtering operations performed by the transceiver in the frequency domain, and specific windowing operations performed by the transceiver in the time domain.

[0190] A slot may consist of one or more symbols in the time domain (such as an Orthogonal Frequency Division Multiplexing (OFDM) symbol, a Single Carrier Frequency Division Multiple Access (SC-FDMA) symbol, etc.) A slot may be a numerology-based time unit.

[0191] A slot may include multiple minislots. Each minislot may consist of one or more symbols in the time domain. A minislot may also be called a subslot. A minislot may consist of fewer symbols than a slot. A PDSCH (or PUSCH) transmitted in a time unit larger than a minislot may be called PDSCH (or PUSCH) mapping type A. A PDSCH (or PUSCH) transmitted using a minislot may be called PDSCH (or PUSCH) mapping type B.

[0192] 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.

[0193] For example, one subframe may be referred to as a transmission time interval (TTI), multiple consecutive subframes may be referred to as a TTI, or one slot or one minislot may be referred to as a TTI. That is, at least one of the subframe and the TTI may be a subframe (1 ms) in existing LTE, a period shorter than 1 ms (e.g., 1-13 symbols), or a period longer than 1 ms. Note that the unit representing the TTI may be called a slot, minislot, etc., instead of a subframe.

[0194] Here, TTI refers to, for example, the smallest time unit for scheduling in wireless communication. For example, in an LTE system, a base station schedules each user terminal to allocate radio resources (such as frequency bandwidth and transmission power that can be used by each user terminal) in TTI units. Note that the definition of TTI is not limited to this.

[0195] 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.

[0196] In addition, when one slot or one minislot is called a TTI, one or more TTIs (i.e., one or more slots or one or more minislots) may be the minimum time unit for scheduling, and the number of slots (minislots) constituting the minimum time unit for scheduling may be controlled.

[0197] A TTI having a time length of 1 ms may be referred to as a regular TTI (TTI in LTE Rel. 8-12), normal TTI, long TTI, regular subframe, normal subframe, long subframe, slot, etc. A TTI shorter than a regular TTI may be referred to as a shortened TTI, short TTI, partial or fractional TTI, shortened subframe, short subframe, minislot, subslot, slot, etc.

[0198] 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.

[0199] A resource block (RB) is a resource allocation unit in the time domain and the frequency domain, and may include one or more consecutive subcarriers in the frequency domain. The number of subcarriers included in an RB may be the same regardless of numerology, for example, 12. The number of subcarriers included in an RB may be determined based on numerology.

[0200] The time domain of an RB may include one or more symbols and may have a length of one slot, one minislot, one subframe, or one TTI, each of which may consist of one or more resource blocks.

[0201] Note that one or more RBs may also be called a physical resource block (PRB), a sub-carrier group (SCG), a resource element group (REG), a PRB pair, an RB pair, etc.

[0202] 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.

[0203] 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.

[0204] 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.

[0205] 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."

[0206] The above-described structures of the radio frame, subframe, slot, minislot, and symbol are merely examples. For example, the number of subframes included in a radio frame, the number of slots per subframe or radio frame, the number of minislots included in a slot, the number of symbols and RBs included in a slot or minislot, the number of subcarriers included in an RB, the number of symbols in a TTI, the symbol length, the cyclic prefix (CP) length, and other configurations may be changed in various ways.

[0207] 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.

[0208] The reference signal may also be abbreviated as Reference Signal (RS) and may be called a pilot depending on the applicable standard.

[0209] 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."

[0210] The "means" in the configuration of each of the above devices may be replaced with "part," "circuit," "device," etc.

[0211] As used in this disclosure, any reference to an element using a designation such as "first," "second," etc. does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient method of distinguishing between two or more elements. Thus, a reference to a first and a second element does not imply that only two elements may be employed therein or that the first element must precede the second element in some way.

[0212] When the terms "include," "including," and variations thereof are used in this disclosure, these terms are intended to be inclusive, similar to the term "comprising." Furthermore, when the term "or" is used in this disclosure, it is not intended to be an exclusive or.

[0213] 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.

[0214] 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.

[0215] 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."

[0216] 19 shows an example of the configuration of a vehicle 2001. As shown in Fig. 19, the vehicle 2001 includes a drive unit 2002, a steering unit 2003, an accelerator pedal 2004, a brake pedal 2005, a shift lever 2006, left and right front wheels 2007, left and right rear wheels 2008, an axle 2009, an electronic control unit 2010, various sensors 2021 to 2029, an information service unit 2012, and a communication module 2013.

[0217] The drive unit 2002 is composed of, for example, an engine, a motor, or a hybrid of an engine and a motor. The steering unit 2003 includes at least a steering wheel (also called a handle) and is configured to steer at least one of the front wheels and the rear wheels based on the operation of the steering wheel operated by the user. The electronic control unit 2010 is composed of a microprocessor 2031, memory (ROM, RAM) 2032, and a communication port (IO port) 2033. Signals from various sensors 2021 to 2027 provided in the vehicle are input to the electronic control unit 2010. The electronic control unit 2010 may also be called an ECU (Electronic Control Unit).

[0218] The signals from the various sensors 2021 to 2028 include a current signal from a current sensor 2021 that senses the current of the motor, a rotation speed signal of the front and rear wheels obtained by a rotation speed sensor 2022, an air pressure signal of the front and rear wheels obtained by an air pressure sensor 2023, a vehicle speed signal obtained by a vehicle speed sensor 2024, an acceleration signal obtained by an acceleration sensor 2025, an accelerator pedal depression amount signal obtained by an accelerator pedal sensor 2029, a brake pedal depression amount signal obtained by a brake pedal sensor 2026, a shift lever operation signal obtained by a shift lever sensor 2027, and a detection signal for detecting obstacles, vehicles, pedestrians, etc. obtained by an object detection sensor 2028.

[0219] The information service unit 2012 is composed of various devices, such as a car navigation system, an audio system, speakers, a television, and a radio, for providing (outputting) various types of information, such as driving information, traffic information, and entertainment information, and one or more ECUs for controlling these devices. The information service unit 2012 uses information acquired from external devices via the communication module 2013, etc., to provide various types of multimedia information and multimedia services to the occupants of the vehicle 1.

[0220] 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.

[0221] The driving assistance system unit 2030 is composed of various devices that provide functions for preventing accidents and reducing the driver's driving burden, such as millimeter-wave radar, LiDAR (Light Detection and Ranging), cameras, positioning locators (e.g., GNSS, etc.), map information (e.g., high-definition (HD) maps, autonomous vehicle (AV) maps, etc.), gyro systems (e.g., IMU (Inertial Measurement Unit), INS (Inertial Navigation System), etc.), AI (Artificial Intelligence) chips, and AI processors, as well as one or more ECUs that control these devices. The driving assistance system unit 2030 also transmits and receives various information via the communication module 2013 to realize driving assistance functions or autonomous driving functions.

[0222] The communication module 2013 can communicate with the microprocessor 2031 and components of the vehicle 1 via the communication port. For example, the communication module 2013 transmits and receives data via the communication port 2033 to and from a driving unit 2002, a steering unit 2003, an accelerator pedal 2004, a brake pedal 2005, a shift lever 2006, left and right front wheels 2007, left and right rear wheels 2008, an axle 2009, a microprocessor 2031 and memory (ROM, RAM) 2032 in the electronic control unit 2010, and sensors 2021 to 2028, which are provided in the vehicle 2001.

[0223] 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.

[0224] The communication module 2013 may transmit at least one of signals from the above-mentioned various sensors 2021 to 2028 input to the electronic control unit 2010, information obtained based on the signals, and information based on input from the outside (user) obtained via the information service unit 2012 to an external device via wireless communication. The electronic control unit 2010, the various sensors 2021 to 2028, the information service unit 2012, etc. may be referred to as input units that accept input. For example, the PUSCH transmitted by the communication module 2013 may include information based on the above-mentioned input.

[0225] The communication module 2013 receives various information (traffic information, traffic signal information, vehicle-to-vehicle information, etc.) transmitted from external devices and displays it on an information service unit 2012 provided in the vehicle. The information service unit 2012 may also be called an output unit that outputs information (for example, outputs information to a device such as a display or speaker based on the PDSCH (or data / information decoded from the PDSCH) received by the communication module 2013). The communication module 2013 also stores the various information received from external devices in a memory 2032 that can be used by the microprocessor 2031. Based on the information stored in the memory 2032, the microprocessor 2031 may control the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, left and right front wheels 2007, left and right rear wheels 2008, axles 2009, sensors 2021 to 2028, and the like provided in the vehicle 2001.

[0226] (Additional Note) The above disclosure may be expressed as follows: A first feature is a radio base station including: a control unit that determines whether to activate or deactivate an execution condition for a terminal that executes cell transition when the execution condition for cell transition is satisfied without following an instruction from a network; and a transmission unit that transmits an instruction to activate or deactivate the execution condition to the terminal.

[0227] A second feature is that, in the first feature, the execution condition is assigned identification information that can identify a beam transmitted from the radio base station, and the control unit determines whether to activate or deactivate the execution condition on a beam-by-beam basis.

[0228] A third feature based on the first or second feature is that the control unit determines to deactivate the execution condition when the execution condition is set for the terminal for the first time.

[0229] A fourth feature is the first to third features, wherein the control unit separately sets a target cell as a transfer destination and sets the execution condition for the terminal.

[0230] A fifth feature is a terminal that includes a control unit that executes a cell transition without an instruction from a network when a condition for executing a cell transition is satisfied, and a receiving unit that receives an instruction from the network to activate or deactivate the execution condition, and the control unit activates or deactivates the execution condition based on the instruction.

[0231] A sixth feature is that, in the fifth feature, the control unit activates the execution condition when it acquires a timing adjustment value of a target cell to which the transition is made, or when it completes acquisition of the timing adjustment value and activation of the transmission setting display state.

[0232] A seventh feature is a radio base station including: a terminal that performs cell transition to a target cell without performing a random access procedure; a control unit that performs early acquisition of a timing adjustment value of the target cell; a receiving unit that receives the timing adjustment value from the target cell; and a transmitting unit that transmits, to the terminal, a control element of a medium access control layer including the timing adjustment value received by the receiving unit.

[0233] According to an eighth feature in the seventh feature, the receiver receives the timing adjustment value after the terminal performs a random access procedure with the target cell.

[0234] According to a ninth feature in the seventh or eighth feature, the transmitter transmits the control element including the timing adjustment value and an instruction to activate an execution condition for cell transfer.

[0235] According to a tenth feature, in any one of the seventh to ninth features, the transmitter transmits the control element including a resource of a random access channel associated with a synchronization signal block.

[0236] An eleventh feature is a terminal including: a control unit that performs cell transition to a target cell without performing a random access procedure; and a receiving unit that receives, from a serving cell, a control element of a medium access control layer including a timing adjustment value of the target cell, wherein the control unit performs cell transition to the target cell using the timing adjustment value received by the receiving unit.

[0237] The twelfth feature based on the eleventh feature is that the receiving unit receives the control element after the terminal performs a random access procedure with the target cell.

[0238] 10 Wireless communication system 20 NG-RAN 100 gNB 110 Wireless communication unit 120 Handover processing unit 130 TA setting unit 140 Control unit 200 UE 210 Wireless communication unit 220 Measurement reporting unit 230 Handover execution unit 240 Control unit 1001 Processor 1002 Memory 1003 Storage 1004 Communication device 1005 Input device 1006 Output device 1007 Bus 2001 Vehicle 2002 Drive unit 2003 Steering unit 2004 Accelerator pedal 2005 Brake pedal 2006 Shift lever 2007 Left and right front wheels 2008 Left and right rear wheels 2009 Axle 2010 Electronic control unit 2012 Information service unit 2013 Communication module 2021 Current sensor 2022 RPM sensor 2023 Air pressure sensor 2024 Vehicle speed sensor 2025 Acceleration sensor 2026 Brake pedal sensor 2027 Shift lever sensor 2028 Object detection sensor 2029 Accelerator pedal sensor 2030 Driving assistance system section 2031 Microprocessor 2032 Memory (ROM, RAM) 2033 Communication port

Claims

1. A radio base station comprising: a terminal that performs cell transition to a target cell without performing a random access procedure; a control unit that performs early acquisition of a timing adjustment value of the target cell; a receiving unit that receives the timing adjustment value from the target cell; and a transmitting unit that transmits to the terminal a control element of a medium access control layer including the timing adjustment value received by the receiving unit.

2. The radio base station according to claim 1, wherein the receiver receives the timing adjustment value after the terminal executes a random access procedure with the target cell.

3. The radio base station according to claim 1, wherein the transmitter transmits the control element including the timing adjustment value and an instruction to activate a condition for performing a cell transfer.

4. The radio base station according to claim 3, wherein the transmitter transmits the control element including a resource of a random access channel associated with a synchronization signal block.

5. A terminal comprising: a control unit that performs cell transition to a target cell without performing a random access procedure; and a receiving unit that receives a control element of a medium access control layer including a timing adjustment value of the target cell from a serving cell, wherein the control unit performs cell transition to the target cell using the timing adjustment value received by the receiving unit.

6. The terminal according to claim 5, wherein the receiver receives the control element after the terminal has performed a random access procedure with the target cell.

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