Terminal and communication method

Abstract

This terminal has: a reception unit that receives a cell switch command of mobility control by a lower layer; and a control unit that performs uplink synchronization with one among a plurality of transmission / reception points of a target cell before reception of the cell switch command, and performs uplink synchronization with the rest of the plurality of transmission / reception points after reception of the cell switch command.

Description

Terminal and communication method

[0001] The present disclosure relates to a terminal and a communication method.

[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 18 discusses extensions to Layer 1 / Layer 2 mobility (L1 / L2 mobility). L1 / L2 mobility, also known as Lower Layer Triggered Mobility (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)) (Non-Patent Document 1). HO based on L1 / L2 mobility is realized by lower layers such as the Medium Access Control layer (MAC).

[0004] L1 / L2 mobility is also planned to be supported between a CU (Central Unit) and a DU (Distributed Unit) of a base station (gNB), and it is also being considered to enable a UE to perform HO without performing a random access procedure (RA procedure) (which may be called RACH-less handover) (Non-Patent Document 1).

[0005] In addition, in 3GPP Release-18, when a configuration with multiple transmission / reception points (TRPs) is adopted, the use of two Timing Advances (TAs) is also being considered (Non-Patent Document 2).

[0006] "Revised WID on Further NR mobility enhancements", RP-223520, 3GPP TSG RAN Meeting #98-e, 3GPP, December 2022 "WID Update: MIMO Evolution for Downlink and Uplink", RP-223276, 3GPP TSG RAN Meeting #98-e, 3GPP, December 2022 3GPP TS 38.401 V18.0.0 (2023-12)

[0007] However, there has been insufficient consideration of the operation of UpLink (UL) synchronization when multiple TRPs are configured in LTM, and there is a possibility that appropriate cell switching will not be performed.

[0008] One aspect of the present disclosure is to provide a terminal and a communication method in which an appropriate cell switch is performed even when a multiple TRP configuration is adopted in LTM.

[0009] A terminal according to one aspect of the present disclosure has a receiving unit that receives a cell switch command in mobility control by a lower layer, and a control unit that performs uplink synchronization with one of a plurality of transmission / reception points of a target cell before receiving the cell switch command, and performs uplink synchronization with the remaining of the plurality of transmission / reception points after receiving the cell switch command.

[0010] A terminal according to one aspect of the present disclosure has a receiving unit that receives a cell switch command in mobility control by a lower layer, and a control unit that performs uplink synchronization with all multiple transmission and reception points of a target cell before receiving the cell switch command.

[0011] A terminal according to one aspect of the present disclosure has a receiving unit that receives a cell switch command in mobility control by a lower layer, and a control unit that performs uplink synchronization with all multiple transmission and reception points of a target cell after receiving the cell switch command.

[0012] FIG. 1 is a schematic diagram of an overall configuration of a wireless communication system according to the present embodiment. FIG. 2 is a diagram illustrating an overview of an LTM signaling procedure. FIG. 3 is a diagram illustrating CSC. FIG. 4 is a diagram illustrating switching from a source cell to a target cell. FIG. 5 is a diagram illustrating an LTM procedure between gNB-DU in intra-NR. FIG. 6 is a diagram illustrating CSC according to proposal 1. FIG. 7 is a diagram illustrating CSC according to proposal 2. FIG. 8 is a diagram illustrating CSC according to proposal 3. FIG. 9 is a block diagram illustrating an example of the configuration of a base station according to the embodiment. FIG. 10 is a block diagram illustrating an example of the configuration of a terminal according to the embodiment. FIG. 11 is a diagram illustrating an example of the hardware configuration of a base station and a terminal according to the embodiment. FIG. 12 is a diagram illustrating an example of the configuration of a vehicle.

[0013] Hereinafter, an embodiment according to one aspect of the present disclosure will be described with reference to the drawings.

[0014] <Wireless System Configuration> Fig. 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 New Radio (NR) and includes a Next Generation-Radio Access Network (hereinafter, NG-RAN 20 and a terminal 200). The wireless communication system 10 may be a wireless communication system conforming to a method called 5G, 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). The terminal is also referred to as User Equipment (UE).

[0015] The NG-RAN 20 includes a base station 100. The base station 100 may be, for example, a gNB or an ng-eNB. The NG-RAN 20 is connected to a core network (e.g., 5GC, not shown) conforming to NR. The NG-RAN 20 and 5GC may simply be referred to as a network. In 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.

[0016] The base station 100 may employ a fronthaul (FH) interface defined by the Open Radio Access Network Alliance (O-RAN). The base station may include an O-RAN Central Unit (O-CU), an O-RAN Distributed Unit (O-DU), and an O-RAN Radio Unit (O-RU). The O-CU, O-DU, and O-RU may be referred to as a CU, a DU, and an RU, respectively, or as a gNB-CU, a gNB-DU, and a gNB-RU.

[0017] The O-DU may be separated from the O-CU and installed in a different geographical location. One or more DUs may be connected to the O-CU. Furthermore, the base stations 100 (gNB-CUs) may be connected via an Xn interface, and the CU and DU may be connected via an F1 interface.

[0018] The NG-RAN 20 is connected to an Access and Mobility Management Function (AMF), which is included in the 5G system architecture and provides a function for managing access and mobility of the terminal 200, a Session Management Function (SMF), which provides a function for managing sessions, and the like. In addition, a UDM / UDR (Unified Data Management / User Data Repository) may be connected to the AMF and / or SMF.

[0019] The base station 100 is a base station that complies with NR and performs NR wireless communication with the terminal 200. The base station 100 and the terminal 200 are capable of supporting Massive MIMO (Multi-Input Multi-Output), which generates a more directional beam by controlling radio signals transmitted from multiple antenna elements, Carrier Aggregation (CA), which uses multiple component carriers (CCs) by bundling them together, and Dual Connectivity (DC), which performs simultaneous communication between multiple NG-RAN nodes and the terminal.

[0020] In this embodiment, multi-radio dual connectivity (MR-DC) may be implemented in which one of the base stations 100 constitutes a master node (MN) and the other base stations 100 constitute secondary nodes (SNs). Specifically, NR-NR dual connectivity (NR-DC) in which an MN (MgNB) and an SN (SgNB) are configured may be implemented. Alternatively, E-UTRA-NR dual connectivity (EN-DC) or NR-E-UTRA dual connectivity (NE-DC) may be implemented.

[0021] In this way, the terminal 200 supports dual connectivity, which allows connection to a plurality of base stations 100 .

[0022] Any of the base stations 100 may be included in a master cell group (MCG), and other base stations 100 may be included in a secondary cell group (SCG). The other base stations 100 may be interpreted as SNs included in the SCG. The MNs or SNs may form cells C1 and C2.

[0023] In the wireless communication system 10, not only mobility control of the terminal 200 in layer 3 (L3 mobility) but also mobility control in layer 1 and / or layer 2 (LTM) may be applied.

[0024] L3 mobility may be interpreted as mobility control at the radio resource control layer (RRC).

[0025] On the other hand, LTM (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). In LTM, for example, an LTM cell switch decision is made in the lower layers such as PHY and MAC and in the DU, and an early cell switch is realized. The terms cell switch, HO, and carrier switch may be used interchangeably.

[0026] LTM may also be supported between the CU and DU of a base station, and may include subsequent LTM, which allows cell switching to be performed continuously without initializing information about candidate cells. Even in this case, LTM and L3 mobility may coexist, and processing based on each may be performed in parallel.

[0027] In a broad sense, the mobility of terminal 200 may mean the ease of movement and maneuverability of terminal 200, but in this embodiment, it may also mean minimizing call drops, radio link (including beam) failures, unnecessary HO, ping-pong states, etc.

[0028] Furthermore, LTM may support RACH-less handover, in which terminal 200 performs handover without performing an RA procedure. Execution of the RA procedure may be interpreted as transmission of a random access channel (PRACH: Physical Random Access Channel) or Msg1 (which may be a random access preamble). RACH-less handover may be referred to as RACH-less LTM or RACH-less cell switch. RACH is an abbreviation for Random Access Channel.

[0029] <LTM Signaling Procedure> FIG. 2 is a diagram illustrating an outline of the LTM signaling procedure.

[0030] 1. The terminal (UE) sends a measurement report to the base station (gNB). The base station decides to configure LTM and starts LTM preparation. 2. The base station sends an RRCReconfiguration message including an LTM candidate configuration to the terminal. 3. The terminal saves the LTM candidate configuration and sends an RRCReconfigurationComplete message to the base station. Steps 1 to 3 may be referred to as LTM preparation. 4a. The terminal performs DL synchronization with a candidate cell before receiving a cell switch command (CSC). 4b. The terminal performs early TA acquisition with a candidate cell before receiving a CSC. TA stands for Time Advance. Steps 4a and 4b may be referred to as early synchronization. 5. The terminal performs L1 measurements in the configured candidate cell and sends an L1 measurement report to the base station. 6. The base station decides to perform a cell switch to the target cell and sends a MAC CE triggering cell switch (cell switch command) including a candidate configuration index of the target cell. The terminal switches to the target cell and applies the configuration indicated by the candidate configuration index. Note that the CSC includes a TA command (see FIG. 3). 7. If the terminal does not have a valid TA for the target cell, it performs an RA procedure toward the target cell. If the terminal has a valid TA for the target cell, it can skip the RA procedure (RACH-less LTM). Steps 5 to 7 may be referred to as LTM cell switch execution. 8. The terminal sends an RRCReconfigurationComplete message to the target cell to complete the LTM cell switch procedure. Step 8 may be referred to as LTM cell switch completion.

[0031] If the RA procedure is executed in step 7, the execution of the LTM cell switch is deemed to have been completed successfully when the RA procedure is completed successfully. On the other hand, in the case of RACH-less LTM, the execution of the LTM cell switch is deemed to have been completed successfully when the network determines that the first UL data has been received successfully.

[0032] <Cell Switch Command: CSC> Fig. 3 is a diagram for explaining the CSC. The CSC is transmitted, for example, from the base station of the source cell to the terminal in L2 (MAC CE).

[0033] The R field indicates a reserved bit.

[0034] The Target Config ID field indicates the index of the candidate target configuration to be applied to the LTM cell switch. The length of the Target Config ID field is 3 bits.

[0035] The TA command field indicates whether TA is valid for the LTM target cell (i.e., the SpCell corresponding to the target configuration indicated by the Target Config ID field). Note that the SpCell is called a Special Cell, which is a collective name for the Primary Cell (PCell) and the Primary SCell (PSCell). The PCell is a CC that ensures connectivity among multiple carriers used in CA. The PSCell is a CC that ensures connectivity among CCs supported by a secondary base station in DC or MR-DC.

[0036] If the value of the TA command field is set to FFF, the TA command field indicates that no valid TA adjustment is available for the Primary Timing Advance Group (pTAG) of the LTM target cell. Otherwise, the TA command field indicates an index value used by the MAC entity to control the amount of timing adjustment and indicates that the terminal can skip the RA procedure for an LTM cell switch. The TA command field is 12 bits long.

[0037] The TCI state ID field indicates the TCI state of the LTM target cell (i.e., the SpCell of the target configuration indicated by the Target Config ID field) to activate. The TCI state ID field indicates the DL TCI state and is 7 bits long. TCI stands for Transmission Configuration Indication. The TCI state can provide information on antenna ports that are quasi-colocated with the antenna ports of the Physical Downlink Control Channel (PDCCH). The terms Quasi-Co-Location (QCL), TCI state, and beam can be used interchangeably.

[0038] The UL TCI state ID field indicates the UL TCI state of the LTM target cell (i.e., the SpCell of the target configuration indicated by the Target Config ID field) to activate. The UL TCI state ID field indicates the UL TCI state and is 8 bits in length.

[0039] The C field indicates the presence of the contention-free Random Access Resources field. If the C field is set to 1, the RA Preamble Index field, S / U field, SS / PBCH Index field, and PRACH Mask Index field are present. If the C field is set to 0, the RA Preamble Index field, SS / PBCH Index field, and PRACH Mask Index field are not present, and the S / U field is considered a reserved field. SS stands for Primary Synchronization Signal (PSS) and Secondary Synchronization Signal (SSS). PBCH stands for Physical Broadcast Channel.

[0040] The S / U field indicates on which UL carrier the PRACH of the contention-free RA resource is transmitted. If the S / U field is set to 1, SUL (supplemental uplink) is used. Otherwise, NUL (normal uplink) is used. The length of the S / U field is 1 bit.

[0041] The RA Preamble Index field indicates the RA preamble index of the contention-free RA resource. The length of the RA Preamble Index field is 6 bits.

[0042] The SS / PBCH index field indicates the SS / PBCH used to determine the RACH occasion for PRACH transmission on a contention-free RA resource. The SS / PBCH index field is 6 bits in length.

[0043] The PRACH Mask Index field indicates the RACH occasion associated with the SS / PBCH indicated by the "SS / PBCH Index" for PRACH transmission on a contention-free RA resource. The PRACH Mask Index field is 4 bits in length.

[0044] <Analysis> There was insufficient consideration given to the operation of UL synchronization when multiple TRPs are configured in LTM, and there is a possibility that appropriate cell switching may not be performed.

[0045] For example, in Fig. 4, a terminal (UE) moves from a source cell to a target cell. If the timing and order of the RACH procedures for UL synchronization are not determined for two TRP1 and TRP2 of the target cell, an appropriate cell switch may not be performed.

[0046] For example, in an LTM consisting of multiple TRPs, if the format of the CSC (information to be notified) is not determined, appropriate cell switching may not be performed. For example, in Figure 4, if the format of the CSC notified from DU1 of the source cell to the terminal is not determined, appropriate cell switching may not be performed.

[0047] Therefore, in the present disclosure, in proposals 1 to 3, techniques are provided for executing an appropriate cell switch.

[0048] <Proposal 1> Before a cell switch, the terminal performs RACH for one of the TRPs to establish UL synchronization. After a cell switch, the terminal performs RACH for the remaining TRPs in the target cell to establish UL synchronization.

[0049] Before a cell switch may be read as before receiving a CSC. After a cell switch may be read as after receiving a CSC. The terms RACH, PRACH, RA, RACH procedure, and RA procedure may be used interchangeably.

[0050] Regarding RACH for multiple TRPs, the following options 1 to 4 are proposed:

[0051] <Proposal 1: Option 1> The terminal performs PDCCH ordered RACH for one of multiple TRPs during early synchronization before a cell switch (in the early synchronization process) to achieve UL synchronization. After a cell switch, the terminal performs PDCCH ordered RACH for the remaining TRPs in the target cell to achieve UL synchronization.

[0052] For example, in Figure 4, a terminal moves from a source cell to a target cell. The terminal performs PDCCH ordered RACH for one TRP1 of two TRPs 1 and 2 at the time of early synchronization before a cell switch, and achieves UL synchronization. After the cell switch, the terminal performs PDCCH ordered RACH for the remaining TRP2 in the target cell, and achieves UL synchronization.

[0053] When the source node instructs the terminal to perform PDCCH ordered RACH, the source node instructs the terminal to perform PDCCH ordered RACH for one TRP. For example, in Figure 4, DU1 of the source cell instructs the terminal to perform PDCCH ordered RACH for TRP1.

[0054] <Proposal 1: Option 1: TA Acquisition> At the time of early synchronization before cell switching, the TRP in which PDCCH ordered RACH is performed acquires TA. For example, in Fig. 4, TRP1 acquires TA.

[0055] The target node (target DU) associates the TA value acquired by the TRP with the TAG ID and transmits it to the source node (source DU) via the F1 interface.

[0056] Figure 5 is a diagram showing an LTM procedure between gNB-DUs in intra-NR. Figure 5 shows the LTM procedure when a terminal moves from one gNB-DU to another gNB-DU in the same gNB-CU. For example, Figure 5 shows the LTM procedure when the terminal shown in Figure 4 moves from DU1 to another DU2 in the same CU. For details of each step in Figure 5, see Chapter 8.2.1.5 of Non-Patent Document 3.

[0057] The candidate gNB-DU associates the TA value acquired by the TRP with the TAG ID and transmits it to the source gNB-DU using the DU-CU TA INFORMATION TRANSFER message shown in "14" in Figure 5 and the CU-DU TA INFORMATION TRANSFER message shown in "15" in Figure 5. For example, DU2 in Figure 4 associates the TA value acquired by TRP1 with the TAG ID and transmits it to DU1 using the DU-CU TA INFORMATION TRANSFER message and the CU-DU TA INFORMATION TRANSFER message.

[0058] The transmission (association) of "TAG ID=0" may be omitted. A TA value for which the association of a TAG ID is omitted may be implicitly interpreted as the TA value of "TAG ID=0" (the TA value of pTAG).

[0059] Note that "1" to "12" in Fig. 5 may correspond to, for example, the LTM preparation in Fig. 2. "13" to "15" in Fig. 5 may correspond to, for example, the early synchronization in Fig. 2. "16" to "22" in Fig. 5 may correspond to, for example, the LTM cell switch execution in Fig. 2. "23" to "26" in Fig. 5 may correspond to the LTM cell switch completion in Fig. 2.

[0060] The correspondence between Figure 5 and Figure 2 is an example. For example, "13" in Figure 5 may correspond to the early operation in Figure 2. For example, after the terminal receives the CSC shown in "18" in Figure 5, the cell switch process (not shown) performed by the terminal may correspond to the LTM cell switch execution in Figure 2.

[0061] The term "target" may be read as "candidate." The term "TA" may be understood as a parameter for adjusting the communication timing of an UL signal. The terms "TA," "TA value," and "TA command" may be used interchangeably.

[0062] <Proposal 1: Option 1: Transmission of TA value and TAG ID> The source DU transmits the TA value and the TAG ID linked to the TA value in a CSC to the terminal.

[0063] Fig. 6 is a diagram illustrating a CSC according to Proposal 1. As shown in Fig. 6, the CSC has a TAG ID field. The TAG ID field indicates the index of a TAG associated with a TA value included in the CSC.

[0064] The TAG ID field of "TAG ID=0" may be omitted and used as an R field. A TA command in which the TAG ID field is omitted may be implicitly interpreted as a TA command with "TAG ID=0".

[0065] <Proposal 1: Option 2> The terminal performs PDCCH ordered RACH for one TRP among multiple TRPs at early synchronization before a cell switch to achieve UL synchronization. At the time of a cell switch (in the cell switch process), the terminal performs RACH such as Contention Based Random Access (CBRA) or Contention Free Random Access (CFRA) with the remaining TRPs to achieve UL synchronization. At the time of a cell switch, "after receiving CSC" may be interpreted as "after receiving CSC."

[0066] For example, in FIG. 4, the UE moves from a source cell to a target cell. At the time of early synchronization before a cell switch, the UE performs a PDCCH ordered RACH for one TRP1 of two TRPs 1 and 2, and achieves UL synchronization. At the time of a cell switch, the UE performs a RACH such as CBRA or CFRA for the remaining TRP2, and achieves UL synchronization. When performing a RACH for CFRA, the UE may perform the RACH using a RACH resource indicated by the CSC.

[0067] When the source node instructs the terminal to perform PDCCH ordered RACH, the source node instructs the terminal to perform PDCCH ordered RACH for one TRP. For example, in Figure 4, DU1 of the source cell instructs the terminal to perform PDCCH ordered RACH for TRP1.

[0068] <Proposal 1: Option 2: TA Acquisition> At the time of early synchronization before cell switching, the TRP in which PDCCH ordered RACH is performed acquires TA. For example, in Fig. 4, TRP1 acquires TA.

[0069] The target node (target DU) associates the TA value acquired by the TRP with the TAG ID and transmits it to the source node (source DU) via the F1 interface.

[0070] For example, DU2 in FIG. 4 associates the TA value acquired by TRP1 with the TAG ID, and transmits it to DU1 using a DU-CU TA INFORMATION TRANSFER message and a CU-DU TA INFORMATION TRANSFER message.

[0071] The transmission (association) of "TAG ID=0" may be omitted. A TA value for which the association of a TAG ID is omitted may be implicitly interpreted as the TA value of "TAG ID=0" (the TA value of pTAG).

[0072] <Proposal 1: Option 2: Transmission of TA Value and TAG ID> The source DU transmits the TA value and the TAG ID associated with the TA value in a CSC to the terminal. For example, as shown in Figure 6, the CSC has a TAG ID field. The TAG ID field indicates the index of the TAG associated with the TA value included in the CSC.

[0073] The TAG ID field of "TAG ID=0" may be omitted and used as an R field. A TA command in which the TAG ID field is omitted may be implicitly interpreted as a TA command with "TAG ID=0".

[0074] <Proposal 1: Option 3> The terminal performs RACH such as CBRA or CFRA for one of the TRPs during early synchronization before a cell switch to achieve UL synchronization. At the time of a cell switch, the terminal performs PDCCH ordered RACH with the remaining TRPs to achieve UL synchronization.

[0075] For example, in Fig. 4, a terminal moves from a source cell to a target cell. At the time of early synchronization before a cell switch, the terminal performs a RACH such as CBRA or CFRA for one TRP1 of two TRPs 1 and 2 to achieve UL synchronization. At the time of a cell switch, the terminal performs a PDCCH ordered RACH for the remaining TRP2 to achieve UL synchronization.

[0076] When a source node instructs a terminal to perform CFRA or CBRA, the source node instructs the terminal to perform CFRA or CBRA for one TRP. For example, in FIG. 4, DU1 of the source cell instructs the terminal to perform CFRA or CBRA for TRP1.

[0077] <Proposal 1: Option 3: Acquire TA> At the time of early synchronization before cell switching, the TRP where CBRA or CFRA is performed acquires TA. For example, in FIG. 4, TRP1 acquires TA.

[0078] The target node (target DU) associates the TA value acquired by the TRP with the TAG ID and transmits it to the source node (source DU) via the F1 interface.

[0079] For example, DU2 in FIG. 4 associates the TA value acquired by TRP1 with the TAG ID, and transmits it to DU1 using a DU-CU TA INFORMATION TRANSFER message and a CU-DU TA INFORMATION TRANSFER message.

[0080] The transmission (association) of "TAG ID=0" may be omitted. A TA value for which the association of a TAG ID is omitted may be implicitly interpreted as the TA value of "TAG ID=0" (the TA value of pTAG).

[0081] <Proposal 1: Option 3: Transmission of TA Value and TAG ID> The source DU transmits the TA value and the TAG ID associated with the TA value in a CSC to the terminal. For example, as shown in Figure 6, the CSC has a TAG ID field. The TAG ID field indicates the index of the TAG associated with the TA value included in the CSC.

[0082] The TAG ID field of "TAG ID=0" may be omitted and used as an R field. A TA command in which the TAG ID field is omitted may be implicitly interpreted as a TA command with "TAG ID=0".

[0083] <Proposal 1: Option 4> The terminal performs RACH such as CBRA or CFRA with one of the TRPs during early synchronization before a cell switch to achieve UL synchronization. The terminal performs RACH such as CBRA or CFRA with the remaining TRPs during a cell switch to achieve UL synchronization.

[0084] For example, in FIG. 4, the UE moves from a source cell to a target cell. At the time of early synchronization before a cell switch, the UE performs a RACH such as CBRA or CFRA with one of two TRPs (TRP1 and TRP2) (TRP1, TRP2) to achieve UL synchronization. At the time of a cell switch, the UE performs a RACH such as CBRA or CFRA with the remaining TRP2 to achieve UL synchronization. When performing a RACH with CFRA, the UE may perform the RACH on a RACH resource indicated by the CSC.

[0085] When a source node instructs a terminal to perform CFRA or CBRA, the source node instructs the terminal to perform CFRA or CBRA for one TRP. For example, in FIG. 4, DU1 of the source cell instructs the terminal to perform CFRA or CBRA for TRP1.

[0086] <Proposal 1: Option 3: Acquire TA> At the time of early synchronization before cell switching, the TRP where CBRA or CFRA is performed acquires TA. For example, in FIG. 4, TRP1 acquires TA.

[0087] The target node (target DU) associates the TA value acquired by the TRP with the TAG ID and transmits it to the source node (source DU) via the F1 interface.

[0088] For example, DU2 in FIG. 4 associates the TA value acquired by TRP1 with the TAG ID, and transmits it to DU1 using a DU-CU TA INFORMATION TRANSFER message and a CU-DU TA INFORMATION TRANSFER message.

[0089] The transmission (association) of "TAG ID=0" may be omitted. A TA value for which the association of a TAG ID is omitted may be implicitly interpreted as the TA value of "TAG ID=0" (the TA value of pTAG).

[0090] <Proposal 1: Option 3: Transmission of TA Value and TAG ID> The source DU transmits the TA value and the TAG ID associated with the TA value in a CSC to the terminal. For example, as shown in Figure 6, the CSC has a TAG ID field. The TAG ID field indicates the index of the TAG associated with the TA value included in the CSC.

[0091] The TAG ID field of "TAG ID=0" may be omitted and used as an R field. A TA command in which the TAG ID field is omitted may be implicitly interpreted as a TA command with "TAG ID=0".

[0092] <Proposal 1: Summary> As described above, the terminal receives a CSC in the LTM. Before receiving the CSC, the terminal performs UL synchronization with one of the multiple TRPs of the target cell, and after receiving the CSC, performs UL synchronization with the remaining TRPs. This operation enables appropriate cell switching even when a multiple TRP configuration is adopted in the LTM.

[0093] <Proposal 2> Before cell switching, the terminal performs RACH for multiple TRPs to achieve UL synchronization.

[0094] For example, the terminal performs PDCCH ordered RACH with all of the multiple TRPs at the time of early synchronization before the cell switch, and achieves UL synchronization. For example, in FIG. 4, the terminal performs PDCCH ordered RACH with two TRPs 1 and 2 at the time of early synchronization before the cell switch, and achieves UL synchronization.

[0095] When the source node instructs the terminal to perform PDCCH ordered RACH, the source node instructs the terminal to perform PDCCH ordered RACH for multiple TRPs. For example, in Figure 4, DU1 of the source cell instructs the terminal to perform PDCCH ordered RACH for TRP1 and TRP2.

[0096] The source node may instruct the terminal to perform PDCCH ordered RACH for multiple TRPs using one PDCCH, or may instruct the terminal to perform PDCCH ordered RACH for multiple TRPs using individual PDCCHs (PDCCHs corresponding to each of the multiple TRPs).

[0097] <Proposal 2: TA Acquisition> During early synchronization before a cell switch, each TRP that performs PDCCH-ordered RACH acquires a TA. For example, in Figure 4, if a terminal performs PDCCH-ordered RACH with TRP1, TRP1 acquires TA1. If a terminal performs PDCCH-ordered RACH with TRP2, TRP2 acquires TA2.

[0098] The target node (target DU) associates the TA value acquired by the TRP with the TAG ID and transmits it to the source node (source DU) via the F1 interface.

[0099] 4 associates the TA1 value acquired by TRP1 with the TAG ID, and associates the TA2 value acquired by TRP2 with the TAG ID. DU2 transmits the associated TA1 value and TAG ID, and the associated TA2 value and TAG ID to DU1 using a DU-CU TA INFORMATION TRANSFER message and a CU-DU TA INFORMATION TRANSFER message.

[0100] The transmission (association) of "TAG ID=0" may be omitted. A TA value for which the association of a TAG ID is omitted may be implicitly interpreted as the TA value of "TAG ID=0" (the TA value of pTAG).

[0101] <Proposal 2: Transmission of TA Value and TAG ID> The source DU transmits the TA value and the TAG ID linked to the TA value in a CSC to the terminal.

[0102] Fig. 7 is a diagram illustrating a CSC according to Proposal 2. As shown in Fig. 7, the CSC has multiple TAG ID fields (two in Fig. 7) and multiple TA command fields corresponding to the multiple TAG ID fields. The multiple TAG ID fields and the multiple TA command fields corresponding to the multiple TAG ID fields correspond to multiple TRPs.

[0103] For example, one TAG ID field and one TA command field shown in Fig. 7 store the TAG ID and TA command for TRP1, and another TAG ID field and another TA command field shown in Fig. 7 store the TAG ID and TA command for TRP2.

[0104] As shown in Figure 7, the CSC has multiple (two in Figure 7) TCI state ID fields, which correspond to multiple TRPs.

[0105] For example, one TCI state ID field shown in Fig. 7 stores the TCI state ID of TRP1, and the other TCI state ID field shown in Fig. 7 stores the TCI state ID of TRP2.

[0106] As shown in Figure 7, the CSC has multiple (two in Figure 7) UL TCI state ID fields, which correspond to multiple TRPs.

[0107] For example, one UL TCI state ID field shown in Figure 7 stores the UL TCI state ID of TRP1, and the other UL TCI state ID field shown in Figure 7 stores the UL TCI state ID of TRP2.

[0108] If a CSC contains multiple TA commands, the TAG ID field of "TAG ID=0" may be omitted and replaced with an R field.

[0109] Fig. 8 is a diagram illustrating a CSC according to Proposal 2. As shown in Fig. 8, one TAG ID field may be omitted. A TA command in which the TAG ID field is omitted may be implicitly interpreted as a TA command with "TAG ID=0". For example, the TA command enclosed by a dotted line frame A8a in Fig. 8 may be interpreted as a TA command with "TAG ID=0".

[0110] <Proposal 2: Modification> The terminal performs RACH such as CBRA or CFRA with multiple TRPs during early synchronization before a cell switch, and achieves UL synchronization. For example, in Fig. 4, the terminal performs RACH such as CBRA or CFRA with two TRPs 1 and 2 during early synchronization before a cell switch, and achieves UL synchronization.

[0111] <Proposal 2: Summary> As described above, the terminal receives the CSC in the LTM. Before receiving the CSC, the terminal performs UL synchronization with multiple TRPs of the target cell. This operation ensures that an appropriate cell switch is performed even when a multiple TRP configuration is adopted in the LTM.

[0112] <Proposal 3> When switching cells, the terminal performs RACH for multiple TRPs to achieve UL synchronization.

[0113] For example, the terminal performs RACH, such as PDCCH ordered RACH, CBRA, or CFRA, with all of the multiple TRPs during a cell switch to achieve UL synchronization. For example, in FIG. 4, the terminal performs RACH, such as PDCCH ordered RACH, CBRA, or CFRA, with two TRPs 1 and 2 during a cell switch to achieve UL synchronization.

[0114] During LTM preparation, the target DU sends multiple RACH resources to the source DU via the F1 interface, where the multiple RACH resources correspond to multiple TRPs of the target cell.

[0115] For example, in FIG. 4, DU2 transmits RACH resources for the terminal to perform RACH for TRP1 and RACH resources for performing RACH for TRP2 to DU1 of the source cell via the F1 interface during LTM preparation.

[0116] The source node includes multiple RACH resources when transmitting a CSC to the terminal.

[0117] Fig. 9 is a diagram illustrating a CSC according to Proposal 3. As shown in dotted lines A9a and A9B in Fig. 9, the CSC has multiple (two in Fig. 9) RACH resource fields. The multiple RACH resource fields correspond to the RACH resources of multiple TRPs.

[0118] For example, the RACH resource field shown in the dotted box A9a corresponds to the RACH resource in TRP1 in Fig. 4. The RACH resource field shown in the dotted box A9b corresponds to the RACH resource in TRP2 in Fig. 4.

[0119] The terminal performs RACH for multiple TRPs based on the RACH resources of the CSC, and achieves UL synchronization. For example, the terminal performs RACH for TRP1 in Fig. 4 using the RACH resources shown by dotted line A9a in Fig. 9, and achieves UL synchronization. The terminal performs RACH for TRP2 in Fig. 4 using the RACH resources shown by dotted line A9b in Fig. 9, and achieves UL synchronization.

[0120] The terminal may perform multiple RACH procedures in sequence, for example, the terminal may perform RACH with TRP1 in FIG. 4 and then perform RACH with TRP2 in FIG. 4.

[0121] The association between the RACH resource and the TRP may be indicated by a Physical Cell Identifier (PCI). For example, the RACH resource and the PCI may be associated in the CSC. For example, the RACH resource of "PCI=1" may be the RACH resource for TRP1, and the RACH resource of "PCI=2" may be the RACH resource for TRP2.

[0122] <Proposal 3: Summary> As described above, the terminal receives the CSC in the LTM. After receiving the CSC, the terminal performs UL synchronization with multiple TRPs of the target cell. This operation ensures that an appropriate cell switch is performed even when a multiple TRP configuration is adopted in the LTM.

[0123] 4, one DU 2 is connected to TRP1 and 2, but a DU may be connected to each of TRP1 and 2. In this case, the DUs connected to TRP1 and 2 may perform LTM signaling in cooperation with each other.

[0124] <Configuration of Base Station> Fig. 10 is a block diagram showing an example of the configuration of a base station 100 according to an embodiment. The base station 100 includes, for example, a transmitting unit 101, a receiving unit 102, and a control unit 103. The base station 100 communicates with a terminal 200 (see Fig. 11) by radio. The base station 100 may be a CU, DU, or CU.

[0125] The transmitter 101 transmits a downlink (DL) signal to the terminal 200. For example, the transmitter 101 transmits the DL signal under the control of the controller 103.

[0126] The DL signal may include, for example, a downlink data signal and control information (e.g., Downlink Control Information (DCI)). The DL signal may also include information indicating scheduling related to signal transmission of terminal 200 (e.g., an UL grant). The DL signal may also include control information of higher layers (e.g., control information of Radio Resource Control (RRC)). The DL signal may also include a reference signal.

[0127] Channels used for transmitting DL signals include, for example, data channels and control channels. For example, the data channels may include a PDSCH (Physical Downlink Shared Channel), and the control channels may include a PDCCH (Physical Downlink Control Channel). For example, the base station 100 transmits control information to the terminal 200 using the PDCCH and transmits downlink data signals using the PDSCH.

[0128] The reference signal included in the DL signal may include at least one of a demodulation reference signal (Demodulation Reference Signal (DMRS)), a Phase Tracking Reference Signal (PTRS), a Channel State Information-Reference Signal (CSI-RS), a Sounding Reference Signal (SRS), and a Positioning Reference Signal (PRS) for position information. For example, reference signals such as DMRS and PTRS are used for demodulating downlink data signals and are transmitted using the PDSCH.

[0129] The receiving unit 102 receives an uplink (UL) signal transmitted from the terminal 200. For example, the receiving unit 102 receives the UL signal under the control of the control unit 103.

[0130] The control unit 103 controls the communication operations of the base station 100 , including the transmission processing of the transmission unit 101 and the reception processing of the reception unit 102 .

[0131] For example, the control unit 103 acquires information such as data and control information from the upper layer and outputs it to the transmitting unit 101. The control unit 103 also outputs the data, control information, etc. received from the receiving unit 102 to the upper layer.

[0132] For example, the control unit 103 allocates resources (or channels) used for transmitting and receiving DL signals and / or resources used for transmitting and receiving UL signals based on signals (e.g., data and control information, etc.) received from the terminal 200 and / or data and control information, etc. acquired from a higher layer. Information related to the allocated resources may be included in control information transmitted to the terminal 200.

[0133] Control unit 103 configures PUCCH resources as an example of allocation of resources used for transmitting and receiving UL signals. Information related to PUCCH configuration such as a PUCCH cell timing pattern (PUCCH configuration information) may be reported to terminal 200 by RRC.

[0134] Here, transmission section 101 transmits an SCS in mobility control by a lower layer. The mobility control by a lower layer may be LTM. Control section 103 performs UL synchronization with terminal 200.

[0135] Control unit 103 may perform UL synchronization with terminal 200 based on the RA based on the PDCCH order before transmitting the CSC, and may perform uplink synchronization with terminal 200 based on the RA based on the PDCCH order after transmitting the CSC. The terms "RA based on the PDCCH order" and "PDCCH ordered RACH" may be used interchangeably.

[0136] Control section 103 may perform UL synchronization with terminal 200 based on RA based on the PDCCH order before transmitting the CSC, and may perform UL synchronization with terminal 200 based on CBRA or CFRA after transmitting the CSC.

[0137] Control section 103 may perform UL synchronization with terminal 200 based on CBRA or CFRA before transmitting the CSC, and may perform UL synchronization with the terminal based on RA based on the PDCCH order after transmitting the CSC.

[0138] Control unit 103 may perform UL synchronization with terminal 200 based on CBRA or CFRA before transmitting the CSC, and may perform UL synchronization with terminal 200 based on CBRA or CFRA after transmitting the CSC.

[0139] 11 is a block diagram showing an example of the configuration of a terminal 200 according to an embodiment. The terminal 200 includes, for example, a receiving unit 201, a transmitting unit 202, and a control unit 203. The terminal 200 communicates with, for example, a base station 10 wirelessly.

[0140] The receiving unit 201 receives a DL signal transmitted from the base station 10. For example, the receiving unit 201 receives the DL signal under the control of the control unit 203.

[0141] The transmitting unit 202 transmits the UL signal to the base station 10. For example, the transmitting unit 202 transmits the UL signal under the control of the control unit 203.

[0142] The UL signal may include, for example, an uplink data signal and control information (e.g., UCI). For example, information related to the processing capability of the terminal 200 (e.g., UE capability) may be included. The UL signal may also include a reference signal.

[0143] Channels used for transmitting UL signals include, for example, data channels and control channels. For example, the data channels include a PUSCH (Physical Uplink Shared Channel), and the control channels include a PUCCH (Physical Uplink Control Channel). For example, the terminal 200 receives control information from the base station 10 using the PUCCH and transmits uplink data signals using the PUSCH.

[0144] The reference signals included in the UL signal may include, for example, at least one of DMRS, PTRS, CSI-RS, SRS, and PRS. For example, the reference signals such as DMRS and PTRS are used for demodulating the uplink data signal and are transmitted using an uplink channel (for example, PUSCH).

[0145] The control unit 203 controls the communication operations of the terminal 200 , including the reception processing in the receiving unit 201 and the transmission processing in the transmitting unit 202 .

[0146] For example, the control unit 203 acquires information such as data and control information from the upper layer and outputs it to the transmitting unit 202. Also, the control unit 203 outputs, for example, the data and control information received from the receiving unit 201 to the upper layer.

[0147] For example, the control unit 203 controls transmission of information to be fed back to the base station 10. The information to be fed back to the base station 10 may include, for example, HARQ-ACK, channel state information (CSI), or a scheduling request (SR). The information to be fed back to the base station 10 may be included in UCI. The UCI is transmitted in the resources of the PUCCH.

[0148] The control unit 203 sets PUCCH resources based on configuration information (for example, configuration information such as a PUCCH cell timing pattern notified by RRC and / or DCI) received from the base station 10. The control unit 203 determines the PUCCH resources to be used for transmitting information to be fed back to the base station 10. Under the control of the control unit 203, the transmission unit 202 transmits the information to be fed back to the base station 10 in the PUCCH resources determined by the control unit 203.

[0149] Note that the channel used for transmitting the DL signal and the channel used for transmitting the UL signal are not limited to the above-mentioned examples. For example, the channel used for transmitting the DL signal and the channel used for transmitting the UL signal may include a Random Access Channel (RACH) and a Physical Broadcast Channel (PBCH). The RACH may be used to transmit Downlink Control Information (DCI) including a Random Access Radio Network Temporary Identifier (RA-RNTI), for example.

[0150] Here, the receiver 201 receives a CSC in mobility control by a lower layer. The controller 203 performs UL synchronization with one of the TRPs of the target cell before receiving the CSC, and performs UL synchronization with the remaining TRPs after receiving the CSC.

[0151] The control unit 203 may perform RA based on the PDCCH order before receiving the CSC to perform UL synchronization with one of the multiple TRPs, and may perform RA based on the PDCCH order after receiving the CSC to perform UL synchronization with the remaining of the multiple TRPs.

[0152] The control unit 203 may perform RA based on the PDCCH order before receiving the CSC to achieve UL synchronization with one of the multiple TRPs, and may perform CBRA or CFRA after receiving the CSC to achieve UL synchronization with the remaining of the multiple TRPs.

[0153] The control unit 203 may perform CBRA or CFRA before receiving the CSC to achieve UL synchronization with one of the multiple TRPs, and may perform RA based on the PDCCH order after receiving the CSC to achieve UL synchronization with the remaining multiple TRPs.

[0154] The control unit 203 may perform CBRA or CFRA before receiving the CSC to achieve UL synchronization with one of the multiple TRPs, and may perform CBRA or CFRA after receiving the CSC to achieve UL synchronization with the remaining multiple TRPs.

[0155] The receiver 201 may receive a CSC in mobility control by a lower layer. The controller 203 may perform UL synchronization with all of the TRPs of the target cell before receiving the CSC.

[0156] Furthermore, the receiver 201 may receive a CSC in mobility control by a lower layer. The controller 203 may perform UL synchronization with all of the multiple TRPs of the target cell after receiving the CSC.

[0157] 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).

[0158] <Hardware Configuration, etc.> The block diagrams used to explain the above embodiments show functional blocks. These functional blocks (components) are realized by any combination of at least one of hardware and software. Furthermore, the method for realizing each functional block is not particularly limited. That is, each functional block may be realized using a single device that is physically or logically coupled, or may be realized using two or more physically or logically separated devices that are directly or indirectly connected (e.g., using wires, wirelessly, etc.) and these multiple devices. The functional block may also be realized by combining software with the single device or the multiple devices.

[0159] Functions include, but are not limited to, judgment, determination, assessment, 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 these functions are implemented.

[0160] For example, a base station, a terminal, or the like 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. 12 is a diagram illustrating an example of the hardware configuration of a base station and a terminal according to the 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, and the like.

[0161] 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.

[0162] Each function in the base station 100 and the terminal 200 is realized by loading specified 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.

[0163] The processor 1001 controls the entire computer by running, for example, an operating system. The processor 1001 may be configured by a central processing unit (CPU) including an interface with peripheral devices, a control device, an arithmetic unit, a register, etc. For example, the above-mentioned control unit 103 and control unit 203 may be realized by the processor 1001.

[0164] 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. For example, the control unit 203 of the terminal 200 may be implemented by a control program stored in the memory 1002 and running on the processor 1001, and similar implementations may be made for other functional blocks. While the above-described various processes have been described as being executed by one processor 1001, they may also be executed simultaneously or sequentially by two or more processors 1001. The processor 1001 may be implemented by one or more chips. The programs may also be transmitted from a network via a telecommunications line.

[0165] The memory 1002 is a computer-readable recording medium and may be configured by, for example, at least one of a read-only memory (ROM), an erasable programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM), a random access memory (RAM), etc. The memory 1002 may also be called a register, a cache, a main memory (primary storage device), etc. The memory 1002 can store executable programs (program codes), software modules, etc. for implementing a wireless communication method according to an embodiment of the present disclosure.

[0166] 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 (registered trademark) disk), a smart card, a flash memory (e.g., a card, a stick, a key drive), a floppy (registered trademark) 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.

[0167] 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, a communication module, etc. The communication device 1004 may be configured to include a high-frequency switch, a duplexer, a filter, a frequency synthesizer, etc. to realize at least one of frequency division duplex (FDD) and time division duplex (TDD). For example, the above-mentioned transmitter 101, receiver 102, receiver 201, transmitter 202, etc. may be realized by the communication device 1004.

[0168] 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. The input device 1005 and the output device 1006 may be integrated into one device (e.g., a touch panel).

[0169] 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.

[0170] 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.

[0171] <Notification of Information, Signaling> Notification of information is not limited to the embodiments described in the present disclosure and may be performed using other methods. For example, 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, 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.

[0172] <Applicable Systems> The embodiments described in the present disclosure are applicable to LTE (Long Term Evolution), LTE-Advanced (LTE-A), SUPER 3G, IMT-Advanced, 4G (4th generation mobile communication system), 5G (5th generation mobile communication system), 6th generation mobile communication system (6G), xth generation mobile communication system (xG) (xG (x is, for example, an integer or a decimal)), 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 802.17 (WiMAX (registered trademark)), IEEE 802.19 (WiMAX (registered trademark)), IEEE 802.20 (WiMAX (registered trademark)), IEEE 802.21 (Wi-Fi (registered trademark)), IEEE 802.22 (WiMAX (registered trademark)), IEEE 802.23 (WiMAX (registered trademark)), IEEE 802.24 (WiMAX (registered trademark)), IEEE 802.25 (WiMAX (registered trademark)), IEEE 802.26 (WiMAX (registered trademark)), IEEE 802.27 (WiMAX (registered trademark)), IEEE 802.28 (WiMAX (registered trademark)), IEEE 802.29 (WiMAX (registered trademark)), IEEE 802.30 (WiMAX (registered trademark)), IEEE 802.31 (Wi-Fi (registered trademark)), IEEE 802.32 (WiMAX (registered trademark)), IEEE 802.33 (WiMAX (registered trademark)), IEEE 802.34 (WiMAX (registered trademark The present invention may be applied to at least one of systems using 802.20, UWB (Ultra-Wide Band), Bluetooth (registered trademark), or other suitable systems, and next-generation systems that are extended, modified, created, or defined based on these systems. The present invention may also be applied to a combination of multiple systems (e.g., a combination of LTE and / or LTE-A with 5G).

[0173] <Processing Procedures, etc.> The processing procedures, sequences, flowcharts, etc. of each aspect / embodiment described in this disclosure may be rearranged unless inconsistent. 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.

[0174] <Operation of Base Station> In the present disclosure, specific operations described as being performed by a base station may also be performed by its upper node in some cases. In a network consisting of one or more network nodes having a base station, it is clear that various operations performed for communication with a terminal may be performed by at least one of the base station and another network node other than the base station (for example, an MME or an S-GW, etc., but are not limited to these). Although the above example illustrates a case where there is one other network node other than the base station, a combination of multiple other network nodes (for example, an MME and an S-GW) may also be used.

[0175] <Direction of Input / Output> Information, etc. (see <Information, Signal>) 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.

[0176] <Handling of Input / Output Information, etc.> Input / output information, etc. may be stored in a specific location (for example, memory) or may be managed using a management table. Input / output information, etc. may be overwritten, updated, or added. Output information, etc. may be deleted. Input information, etc. may be sent to another device.

[0177] <Determination 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 comparison of numerical values ​​(e.g., comparison with a predetermined value).

[0178] <Variations of Aspects, etc.> Each aspect / embodiment described in the present disclosure may be used alone, in combination, or switched depending on the implementation. In addition, 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).

[0179] 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.

[0180] <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.

[0181] 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.

[0182] 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., which 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.

[0183] 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.

[0184] <System, Network> As used in this disclosure, the terms "system" and "network" are used interchangeably.

[0185] <Parameter and Channel Names> Furthermore, the information, parameters, and the like described in the present disclosure may be expressed using absolute values, relative values ​​from a predetermined value, or other corresponding information. For example, a radio resource may be indicated by an index.

[0186] 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.

[0187] <Base Station> In the present 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. A base station may also be referred to by terms such as a macrocell, a small cell, a femtocell, and a picocell.

[0188] 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 partitioned into multiple smaller areas, and each smaller area can also be provided with communication services by a base station subsystem (e.g., a remote radio head (RRH)). The terms "cell" or "sector" refer to part or the entire coverage area of ​​a base station and / or base station subsystem that provides communication services within that coverage area.

[0189] 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.

[0190] Mobile Station In this disclosure, the terms "Mobile Station (MS)," "user terminal," "User Equipment (UE)," "terminal," and the like may be used interchangeably.

[0191] 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.

[0192] <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 an autonomous mobile object operating based on an operational command. It may be a vehicle (e.g., a car, an airplane, etc.), an unmanned mobile object (e.g., a drone, an autonomous vehicle, etc.), or a robot (manned or unmanned). At least one of the base station and the mobile station may be a device that does not necessarily move during communication operations. For example, at least one of the base station and the mobile station may be an IoT (Internet of Things) device such as a sensor.

[0193] Furthermore, the 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, Device-to-Device (D2D) or Vehicle-to-Everything (V2X)). 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.

[0194] 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.

[0195] Fig. 13 shows an example configuration of a vehicle 2001. As shown in Fig. 13, 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.

[0196] 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.

[0197] 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).

[0198] 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.

[0199] 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 that control these devices. The information service unit 2012 provides various types of multimedia information and multimedia services to the occupants of the vehicle 2001 by using information acquired from external devices via the communication module 2013, etc.

[0200] 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.

[0201] The driving assistance system unit 2030 is composed of various devices that provide functions for preventing accidents and reducing the driving burden on the driver, 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. In addition, the driving assistance system unit 2030 transmits and receives various information via the communication module 2013 to realize the driving assistance function or the autonomous driving function.

[0202] 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.

[0203] 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.

[0204] The communication module 2013 may transmit at least one of signals from the above-mentioned various sensors 2021 to 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 to 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.

[0205] The communication module 2013 receives various information (traffic information, traffic signal information, vehicle distance information, etc.) transmitted from an external device 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)).

[0206] 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.

[0207] <Meaning and Interpretation of Terms> 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 a table, database, or other data structure), ascertaining something that is considered to be a "judging" or "determining," 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 that are considered to be a "judging" or "determining." 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.

[0208] 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.

[0209] <Reference Signal> A reference signal can also be abbreviated as RS (Reference Signal), and may also be called a pilot depending on the applicable standard.

[0210] <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."

[0211] "First," "Second" Any reference to an element using designations such as "first," "second," etc., used in this disclosure 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 precede the second element in some way.

[0212] <Means> The "means" in the configuration of each device above may be replaced with "section," "circuit," "device," etc.

[0213] Open Format: 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.

[0214] <Time Units such as TTI, Frequency Units such as RB, and 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 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.

[0215] Numerology may be a communication parameter that applies to the transmission and / or reception of a signal or channel, and 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 structure, specific filtering operations performed by the transceiver in the frequency domain, and specific windowing operations performed by the transceiver in the time domain.

[0216] A slot may be composed of one or more symbols in the time domain (such as an Orthogonal Frequency Division Multiplexing (OFDM) symbol or a Single Carrier Frequency Division Multiple Access (SC-FDMA) symbol). A slot may be a time unit based on numerology.

[0217] 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.

[0218] 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.

[0219] 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.

[0220] 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. Note that the definition of TTI is not limited to this.

[0221] 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.

[0222] 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.

[0223] 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.

[0224] 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 greater than or equal to 1 ms.

[0225] 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.

[0226] 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.

[0227] 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.

[0228] 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.

[0229] 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 BWP and numbered within the BWP.

[0230] 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.

[0231] 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."

[0232] The above-described structures of radio frames, subframes, slots, minislots, symbols, etc. are merely examples, and various changes may be made to 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.

[0233] <Maximum Transmit Power> The "maximum transmit power" in the present disclosure may refer to the maximum value of transmit power, the nominal UE maximum transmit power, or the rated UE maximum transmit power.

[0234] Articles 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.

[0235] <"Different"> In the present disclosure, the term "A and B are different" may mean "A and B are different from each other." Note that 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."

[0236] One aspect of the present disclosure is useful in wireless communication systems.

[0237] 10 Wireless communication system 20 NG-RAN 100 Base station 200 Terminal 101, 202 Transmitter 102, 201 Receiver 103, 203 Controller

Claims

1. A terminal having: a receiving unit that receives a cell switch command in mobility control by a lower layer; and a control unit that performs uplink synchronization with one of multiple transmission / reception points of a target cell before receiving the cell switch command, and performs uplink synchronization with the remaining of the multiple transmission / reception points after receiving the cell switch command.

2. The terminal according to claim 1, wherein the control unit performs random access based on a Physical Downlink Control Channel (PDCCH) order before receiving the cell switch command to achieve uplink synchronization with one of the plurality of transmission / reception points, and performs random access based on a PDCCH order after receiving the cell switch command to achieve uplink synchronization with the remaining of the plurality of transmission / reception points.

3. The terminal according to claim 1, wherein the control unit performs random access based on a PDCCH order before receiving the cell switch command to achieve uplink synchronization with one of the plurality of transmission / reception points, and performs Contention Based Random Access (CBRA) or Contention Free Random Access (CFRA) after receiving the cell switch command to achieve uplink synchronization with the remaining of the plurality of transmission / reception points.

4. A terminal having: a receiving unit that receives a cell switch command in mobility control by a lower layer; and a control unit that performs uplink synchronization with all of a plurality of transmitting and receiving points of a target cell before receiving the cell switch command.

5. A terminal having: a receiving unit that receives a cell switch command in mobility control by a lower layer; and a control unit that performs uplink synchronization with all of a plurality of transmission and reception points of a target cell after receiving the cell switch command.

6. A communication method in which a terminal receives a cell switch command in mobility control by a lower layer, performs uplink synchronization with one of a plurality of transmission / reception points of a target cell before receiving the cell switch command, and performs uplink synchronization with the remaining of the plurality of transmission / reception points after receiving the cell switch command.

Images