Communication device, base station, and communication method

Abstract

To provide user equipment, a base station, and a communication method that enable appropriate control of transmission timing of an uplink signal for a second cell when a first cell that is a serving cell and the second cell that belongs to the same frequency as the first cell are set.SOLUTION: In a mobile communication system, user equipment in which a first cell C1 and a second cell C2 are set by a base station that manages the first cell and the second cell that belongs to the same frequency as the first cell, upon receiving RA resource information indicating a random access resource to be used in random access to the second cell from the first cell, determines a random access preamble to be transmitted in random access using the RA resource information, transmits the determined random access preamble to the second cell, and receives, from the base station, a response to the random access preamble, including timing advance for adjusting transmission timing of an uplink signal to the second cell.SELECTED DRAWING: Figure 15

Description

[Technical Field]

[0001] The present invention relates to a user equipment, a base station, and a communication method used in a mobile communication system. [Background technology]

[0002] In the 3GPP (3rd Generation Partnership Project), a standardization project for mobile communication systems, the introduction of multiple transmission / reception point (TRP) transmission is being considered as an extension of MIMO (multi-input multi-output).

[0003] In a scenario of multiple TRP transmission, a model is assumed in which a first cell, which is a serving cell, and a second cell belonging to the same frequency (intra-frequency) as the first cell are configured in a user equipment, and the user equipment performs data communication with the second cell while maintaining the first cell as the serving cell (see Non-Patent Documents 1 to 3). Here, the second cell is configured with a TRP different from that of the first cell and has a physical cell identity (PCI) different from that of the first cell (cell having TRP with different PCI).

[0004] In order to compensate for propagation delay, user equipment (UE) devices located far from a cell transmit uplink signals earlier than user equipment (UE) devices located close to the cell. Specifically, the UEs adjust the transmission timing of their uplink signals based on the timing advance received from the base station. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] 3GPP contribution: RP-211190, “Discussion on work scope for Rel-17 feNR-MIMO in RAN2” [Non-patent document 2] 3GPP contribution: R2-2106787, “LS Reply on TCI State Update for L1 / L2-Centric Inter-Cell Mobility” [Non-patent document 3] 3GPP contribution: RP-211586, “Revised WID: Further enhancements on MIMO for NR” Summary of the Invention [Problem to be solved by the invention]

[0006] In the above-mentioned multiple TRP transmission scenario, it is considered that the user equipment needs to adjust the transmission timing of the uplink signal for each of the first cell and the second cell. However, a method for adjusting the uplink transmission timing for the second cell has not been realized, and there is a concern that the transmission timing of the uplink signal for the second cell cannot be appropriately controlled.

[0007] Therefore, an object of the present invention is to provide a user equipment, a base station, and a communication method that, when a first cell that is a serving cell and a second cell that belongs to the same frequency as the first cell are configured, enable appropriate control of the transmission timing of an uplink signal to the second cell. [Means for solving the problem]

[0008] A user equipment (100) according to a first aspect is a user equipment (100) in which a first cell (C1) that is a serving cell and a second cell (C2) that belongs to the same frequency as the first cell (C1) are configured by a base station (200) that manages the first cell (C1) and the second cell (C2). The user equipment (100) includes: a receiver (112) that receives, from the first cell (C1), RA resource information indicating a random access resource to be used in random access to the second cell (C2); a controller (120) that determines a random access preamble to be transmitted in the random access using the RA resource information; and a transmitter (111) that transmits the determined random access preamble to the second cell (C2). The receiver (112) receives, from the base station (200), a response to the random access preamble that includes a timing advance for adjusting the transmission timing of an uplink signal to the second cell (C2).

[0009] A base station (200) according to a second aspect is a base station (200) that configures a first cell (C1) that is a serving cell and a second cell (C2) that belongs to the same frequency as the first cell (C1) for a user device (100). The base station includes: a transmitter (211) that transmits RA resource information indicating a random access resource to be used in random access to the second cell (C2) to the user device (100) in the first cell (C1); and a receiver (212) that receives a random access preamble transmitted using the random access resource from the user device (100) in the second cell (C2). The transmitter (211) transmits a response to the random access preamble to the user device (100), the response including a timing advance for adjusting the transmission timing of an uplink signal to the second cell (C2).

[0010] A communication method according to a third aspect is a communication method executed in a user equipment (100) in which a first cell (C1) that is a serving cell and a second cell (C2) that belongs to the same frequency as the first cell (C1) are configured by a base station (200) that manages the first cell (C1) and the second cell (C2). The communication method includes the steps of receiving, from the first cell (C1), RA resource information indicating a random access resource to be used in random access to the second cell (C2), determining a random access preamble to be transmitted in the random access using the RA resource information, transmitting the determined random access preamble to the second cell (C2), and receiving, from the base station (200), a response to the random access preamble that includes a timing advance for adjusting the transmission timing of an uplink signal to the second cell (C2). [Effects of the Invention]

[0011] According to one aspect of the present invention, when a first cell that is a serving cell and a second cell that belongs to the same frequency as the first cell are configured, it is possible to provide a user equipment, a base station, and a communication method that can appropriately control the transmission timing of an uplink signal to the second cell. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram illustrating a configuration of a mobile communication system according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating an example of the configuration of a protocol stack in the mobile communication system according to the embodiment. [Figure 3] 1 is an explanatory diagram for explaining the relationship between an uplink frame and a downlink frame in a mobile communication system according to an embodiment. FIG. [Figure 4] FIG. 1 is a diagram illustrating an assumed scenario in a mobile communication system according to an embodiment. [Figure 5] FIG. 1 is a diagram illustrating a basic procedure in a hypothetical scenario according to an embodiment. [Figure 6] FIG. 1 is a diagram illustrating a configuration of a UE according to an embodiment. [Figure 7] FIG. 2 is a diagram illustrating a configuration of a base station according to an embodiment. [Figure 8] FIG. 2 is a diagram showing a sequence of a first operation example in the mobile communication system according to the embodiment. [Figure 9] FIG. 2 is an explanatory diagram illustrating a first operation example in the mobile communication system according to the embodiment. [Figure 10] FIG. 10 is a diagram showing a sequence of a second operation example in the mobile communication system according to the embodiment. [Figure 11] FIG. 10 is an explanatory diagram illustrating a second operation example in the mobile communication system according to the embodiment. [Figure 12] FIG. 10 is a diagram showing a sequence of a third operation example in the mobile communication system according to the embodiment. [Figure 13] FIG. 10 is a diagram showing a sequence (part 1) of a fourth operation example in the mobile communication system according to the embodiment. [Figure 14] FIG. 10 is a diagram showing a sequence (part 2) of a fourth operation example in the mobile communication system according to the embodiment. [Figure 15] FIG. 10 is a diagram showing a sequence of a fifth operation example in the mobile communication system according to the embodiment. [Figure 16] FIG. 10 is a diagram showing a sequence of a sixth operation example in the mobile communication system according to the embodiment. [Figure 17] FIG. 11 is a diagram showing a sequence of a seventh operation example in the mobile communication system according to the embodiment. [Figure 18] FIG. 13 is a diagram showing a sequence of an eighth operation example in the mobile communication system according to the embodiment. [Figure 19] FIG. 13 is an explanatory diagram illustrating a MAC CE of an eighth operation example in the mobile communication system according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] A mobile communication system according to an embodiment will be described with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[0014] (Configuration of a mobile communication system) The configuration of a mobile communication system 1 according to an embodiment will be described with reference to Fig. 1. The mobile communication system 1 is, for example, a system that complies with the 3GPP Technical Specification (TS). In the following, the mobile communication system 1 will be described using as an example a 5th Generation System (5GS) of the 3GPP standard, that is, a mobile communication system based on NR (New Radio).

[0015] The mobile communication system 1 includes a network 10 and user equipment (UE) 100 that communicates with the network 10. The network 10 includes a next generation radio access network (NG-RAN) 20 that is a 5G radio access network, and a 5G core network (5GC) 30 that is a 5G core network.

[0016] The UE 100 is a device used by a user. The UE 100 is a mobile device, such as a mobile phone terminal such as a smartphone, a tablet terminal, a laptop PC, a communication module, or a communication card. The UE 100 may be a vehicle (e.g., a car, a train, etc.) or a device provided therein. The UE 100 may be a transport vehicle other than a vehicle (e.g., a ship, an airplane, etc.) or a device provided therein. The UE 100 may be a sensor or a device provided therein. Note that the UE 100 may be called by other names such as a mobile station, a mobile terminal, a mobile device, a mobile unit, a subscriber station, a subscriber terminal, a subscriber device, a subscriber unit, a wireless station, a wireless terminal, a wireless device, a wireless unit, a remote station, a remote terminal, a remote device, or a remote unit.

[0017] The NG-RAN 20 includes multiple base stations 200. Each base station 200 manages at least one cell. A cell constitutes the smallest unit of a communication area. For example, one cell belongs to one frequency (carrier frequency) and is composed of one component carrier. The term "cell" may refer to wireless communication resources or to a communication target of the UE 100. Each base station 200 can perform wireless communication with the UE 100 located in its own cell. The base station 200 communicates with the UE 100 using a RAN protocol stack. The base station 200 provides NR user plane and control plane protocol termination for the UE 100 and is connected to the 5GC 30 via an NG interface. Such an NR base station 200 is sometimes referred to as a gNodeB (gNB).

[0018] The 5GC 30 includes a core network device 300. The core network device 300 includes, for example, an Access and Mobility Management Function (AMF) and / or a User Plane Function (UPF). The AMF performs mobility management for the UE 100. The UPF provides functions specialized for user plane processing. The AMF and the UPF are connected to the base station 200 via an NG interface.

[0019] An example of the configuration of a protocol stack in the mobile communication system 1 according to the embodiment will be described with reference to FIG.

[0020] The protocol for the wireless section between UE 100 and base station 200 includes a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, and a radio resource control (RRC) layer.

[0021] The PHY layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Data and control information are transmitted between the PHY layer of the UE 100 and the PHY layer of the base station 200 via a physical channel.

[0022] A physical channel consists of multiple OFDM symbols in the time domain and multiple subcarriers in the frequency domain. One subframe consists of multiple OFDM symbols in the time domain. A resource block is a resource allocation unit and consists of multiple OFDM symbols and multiple subcarriers. A frame can be configured for 10 ms and can include 10 subframes, each of which is 1 ms long. A subframe can include the number of slots corresponding to the subcarrier spacing.

[0023] Among the physical channels, the Physical Downlink Control Channel (PDCCH) plays a central role for purposes such as downlink scheduling assignment, uplink scheduling grant, and transmit power control.

[0024] In NR, the UE 100 can use a bandwidth narrower than the system bandwidth (i.e., the cell bandwidth). The base station 200 configures the UE 100 with a bandwidth portion (BWP) consisting of consecutive PRBs. The UE 100 transmits and receives data and control signals in the active BWP. For example, up to four BWPs can be configured for the UE 100. Each BWP may have a different subcarrier spacing or may overlap in frequency. When multiple BWPs are configured for the UE 100, the base station 200 can specify which BWP to activate by controlling the downlink. This allows the base station 200 to dynamically adjust the UE bandwidth according to the amount of data traffic of the UE 100, etc., and can reduce UE power consumption.

[0025] For example, base station 200 can configure up to three control resource sets (CORESETs) for each of up to four BWPs on the serving cell. A CORESET is a radio resource for control information to be received by UE 100. Up to 12 CORESETs can be configured for UE 100 on the serving cell. Each CORESET has an index of 0 to 11. For example, a CORESET consists of six resource blocks (PRBs) and one, two, or three consecutive OFDM symbols in the time domain.

[0026] The MAC layer performs data priority control, retransmission processing using Hybrid ARQ (HARQ), random access procedures, etc. Data and control information are transmitted between the MAC layer of UE 100 and the MAC layer of base station 200 via a transport channel. The MAC layer of base station 200 includes a scheduler. The scheduler determines the uplink and downlink transport format (transport block size, modulation and coding scheme (MCS)) and the resources to be allocated to UE 100.

[0027] The RLC layer transmits data to the RLC layer on the receiving side using the functions of the MAC layer and PHY layer. Data and control information are transmitted between the RLC layer of the UE 100 and the RLC layer of the base station 200 via logical channels.

[0028] The PDCP layer performs header compression / decompression and encryption / decryption.

[0029] An SDAP (Service Data Adaptation Protocol) layer may be provided above the PDCP layer, which maps IP flows, which are units for QoS control by the core network, to radio bearers, which are units for QoS control by the AS (Access Stratum).

[0030] The RRC layer controls logical channels, transport channels, and physical channels according to the establishment, re-establishment, and release of radio bearers. RRC signaling for various settings is transmitted between the RRC layer of the UE 100 and the RRC layer of the base station 200. When there is an RRC connection between the RRC of the UE 100 and the RRC of the base station 200, the UE 100 is in an RRC connected state. When there is no RRC connection between the RRC of the UE 100 and the RRC of the base station 200, the UE 100 is in an RRC idle state. When the RRC connection between the RRC of the UE 100 and the RRC of the base station 200 is suspended, the UE 100 is in an RRC inactive state.

[0031] The NAS layer located above the RRC layer performs session management and mobility management for the UE 100. NAS signaling is transmitted between the NAS layer of the UE 100 and the NAS layer of the core network device 300 (AMF). Note that the UE 100 has an application layer and the like in addition to a radio interface protocol.

[0032] (Method for adjusting uplink transmission timing) An example of a method for adjusting uplink transmission timing in the mobile communication system 1 according to the embodiment will be described with reference to Fig. 3. That is, a method for synchronizing uplink transmission timing will be described.

[0033] The base station 200 controls the transmission timing of the uplink signal from each UE 100 in the cell under its management so that the reception timing of the uplink signal from each UE 100 falls within a predetermined time range. The base station 200 determines a timing advance (hereinafter, TA) for the UE 100 to adjust the transmission timing of the uplink signal. The base station 200 provides the determined TA to each UE 100.

[0034] The UE 100 adjusts the timing of uplink transmission based on the downlink frame timing. The UE 100 uses TA to adjust the uplink frame timing relative to the downlink frame. As shown in FIG. 4, the UE 100 shifts the i-th uplink frame forward relative to the i-th downlink frame by a time of (NTA+NTA,offset)Tc. The UE 100 calculates an adjustment value (TTA) to be shifted relative to the downlink frame, for example, using the following formula:

[0035]

number

[0036] NTA is a value (referred to as a TA value as appropriate) calculated based on the TA (TA) notified from base station 200 (cell). NTA can be calculated using Equations 2 and 3.

[0037] TA (TA) in Equation 2 is the value of the timing advance command (TA command) included in the medium access control (MAC) control element (CE). In response to receiving the TA command, UE 100 calculates a new TA value (NTA_NEW) from the TA value (NTA_old) it has stored. TA (TA) in Equation 3 is the timing advance value included in the random access response. Note that μ is the subcarrier spacing setting.

[0038] NTA,offset is a fixed offset value used to calculate the adjustment value (TTA). NTA,offset may be notified from base station 200 (cell). When UE 100 is not notified of NTA,offset from base station 200, UE 100 may determine NTA,offset as a default value. UE 100 may determine the offset value (NTA,offset) based on conditions such as the frequency band, the presence or absence of MR-DC, and the presence or absence of coexistence of NR and NB-IoT. UE 100 may determine the offset value (NTA,offset) using, for example, Table 1 below.

[0039] [Table 1]

[0040] Tc is a basic time unit. Tc is a predetermined fixed value. The UE 100 stores information about Tc in advance. Tc is, for example, 0.509 ns.

[0041] The downlink frame timing, which is the reference for adjusting the timing of uplink transmission, is the timing of the beginning of the downlink frame. Specifically, the downlink frame timing is defined as the time when the first detected path (within the time period) of the downlink frame is received from base station 200 (specifically, the reference cell). Note that the radio frames constituting the uplink and downlink frames are made up of ten 1-ms subframes. Each frame is divided into two half-frames of the same size, each consisting of five subframes.

[0042] UE 100 can grasp the downlink frame timing in the BWP in which the SSB is received by performing downlink timing synchronization using a synchronization signal included in a reference signal (SSB: SS / PBCH Block) transmitted in the BWP.

[0043] The SSB includes a Primary Synchronization Signal (PSS), a Secondary Synchronization Signal (SSS), a Physical Broadcast Channel (PBCH), and a Demodulation Reference Signal (DMRS). For example, an SSB may consist of four consecutive OFDM symbols in the time domain. Alternatively, an SSB may consist of 240 consecutive subcarriers (i.e., 20 resource blocks) in the frequency domain. The PBCH is a physical channel that carries a Master Information Block (MIB).

[0044] (Assumed scenario) With reference to FIG. 4, an assumed scenario in the mobile communication system 1 according to the embodiment will be described.

[0045] The base station 200 includes a TRP 201#1, a TRP 201#2, a DU (Distributed Unit) 202, and a CU (Central Unit) 203. While an example in which the base station 200 is separated into the DU 202 and the CU 203 is shown in Fig. 4, the base station 200 does not necessarily have to be separated into the DU 202 and the CU 203. Furthermore, while an example in which the number of TRPs 201 in the base station 200 is two is shown, the number of TRPs 201 in the base station 200 may be three or more.

[0046] The TRP201#1 and the TRP201#2 are distributed and constitute different cells. Specifically, the TRP201#1 forms a cell C1, and the TRP201#2 forms a cell C2.

[0047] Cell C1 and cell C2 belong to the same frequency. Cell C1 and cell C2 have different physical cell identities (PCIs). That is, cell C2 is configured with a TRP#2 that is different from the TRP201#1 corresponding to cell C1, and has a different PCI from cell C1 (cell having TRP with different PCI). Although FIG. 4 shows an example in which the coverage of cell C2 is within the coverage of cell C1, the coverage of cell C2 may at least partially overlap with the coverage of cell C1.

[0048] The DU202 controls the TRP201#1 and TRP201#2. In other words, the TRP201#1 and TRP201#2 are under the control of the same DU202. The DU202 is a unit including lower layers included in the above-mentioned protocol stack, such as the RLC layer, MAC layer, and PHY layer. The DU202 is connected to the CU203 via an F1 interface, which is a fronthaul interface.

[0049] The CU 203 controls the DU 202. The CU 203 is a unit including upper layers included in the above-mentioned protocol stack, such as an RRC layer, an SDAP layer, and a PDCP layer. The CU 203 is connected to the core network (5GC 30) via an NG interface, which is a backhaul interface.

[0050] The UE 100 is in an RRC connected state and performs wireless communication with the base station 200. NR is capable of wideband transmission using high frequency bands such as millimeter waves, but to compensate for radio wave attenuation in such high frequency bands, beamforming is used between the base station 200 and the UE 100 to obtain a high beam gain. The base station 200 and the UE 100 establish a beam pair.

[0051] The UE 100 is serving cell Specifically, the UE 100 performs data communication with the cell C1 using a beam corresponding to the transmission configuration indicator (TCI) state #1. In addition to the cell C1, the UE 100 also has a cell C1 (TRP201#1) that is a non-serving cell. C For example, the UE 100 is configured with an SSB (SS / PBCH Block) for performing beam measurement for the cell C2, and C The radio resources for data communication with the mobile station 2 are set from the cell C1.

[0052] UE 100 reports the beam measurement results for cell C2 to cell C1. Base station 200 (DU 202) receives the beam measurement results from UE 100 in cell C1 and activates TCI state #2 corresponding to the beam of cell C2 based on the beam measurement results.

[0053] Thus, in the embodiment, in a scenario of multiple TRP transmission, a model is assumed in which cell C1, which is a serving cell, and cell C2, which belongs to the same frequency (intra-frequency) as cell C1, are configured for UE100, and UE100 maintains cell C1 as the serving cell while performing data communication with cell C2.

[0054] With reference to FIG. 5, a basic procedure in an assumed scenario according to the embodiment will be described.

[0055] In step S1, the UE 100 receives configuration information from the cell C1 (TRP201#1) by, for example, RRC signaling. The configuration information includes SSB configurations used for beam measurement for the cell C2 (TRP201#2) and configurations required for using radio resources for data transmission and reception (including data transmission and reception with the cell C2). The configuration information may be transmitted from the CU 203 to the UE 100 via the DU 202 and the cell C1 (TRP201#1).

[0056] In step S2, UE 100 performs beam measurement for cell C2 (TRP201#2) using the setting information (particularly, SSB setting) received in step S1 (step S2a), and transmits a report including the measurement result to cell C1 (TRP201#1) (step S2b). DU 202 receives the beam measurement result via cell C1 (TRP201#1).

[0057] In step S3, based on the beam measurement result received in step S2, DU202 transmits an instruction to UE100 via cell C1 (TRP201#1) to activate the TCI state associated with cell C2 (TRP201#2). Such an activation instruction is performed by signaling of layer 1 (PHY layer) and layer 2 (MAC layer, etc.). In response to receiving the activation instruction from cell C1, UE100 activates the TCI state associated with cell C2 (TRP201#2). As a result, a beam pair between UE100 and cell C2 (TRP201#2) is established.

[0058] In step S4, the UE 100 transmits and receives data to and from the cell C2 (TRP201#2) using a UE-dedicated channel on the cell C2 (TRP201#2). The DU 202 transmits and receives data to and from the UE 100 via the cell C2 (TRP201#2).

[0059] The UE 100 is within the coverage of the cell C1 (TRP201#1) and receives a broadcast channel (BCCH) and a paging channel (PCH), which are common channels, from the cell C1 (TRP201#1).

[0060] According to such a scenario and procedure, the UE 100 can switch data communication from the cell C1 (TRP201#1) to the cell C2 (TRP201#2) by beam management in layer 1 (PHY layer) and layer 2 (MAC layer, etc.) without relying on a switching instruction from a higher layer (particularly, the RRC layer) and without performing handover from the cell C1 (TRP201#1) to the cell C2 (TRP201#2). That is, the cell for performing data communication can be realized by beam switching by layer 1 (PHY layer) and layer 2 (MAC layer, etc.).

[0061] In the above-described scenario, it is considered that the UE 100 needs to adjust the transmission timing of the uplink signal for each of the cell C1 (TRP201#1) and the cell C2 (TRP201#2). However, a method for adjusting the uplink transmission timing for the cell C2 (TRP201#2) has not been realized, and there is a concern that the transmission timing of the uplink signal for the cell C2 (TRP201#2) cannot be appropriately controlled. In one embodiment described later, a method for appropriately controlling the transmission timing of the uplink signal for the cell C2 (TRP201#2) will be described.

[0062] In the above scenario, the UE 100 may acquire a timing advance (TA) by random access in order to adjust the uplink transmission timing for the cell C2 (TRP201#2). However, how to perform the random access is not specified. Therefore, there is a concern that the UE 100 may not be able to appropriately acquire the TA by random access in order to adjust the uplink transmission timing for the cell C2 (TRP201#2). In one embodiment described later, a method for appropriately acquiring the TA by random access in order to adjust the uplink transmission timing for the cell C2 (TRP201#2) will be described.

[0063] Furthermore, in the above-described scenario, it is considered that the base station 200 transmits a timing advance (TA) to the UE 100 by the MAC CE in order to adjust the uplink transmission timing for the cell C2 (TRP201#2). However, in the existing MAC CE, a TA command as a timing advance is associated with an identifier of a timing advance group. For this reason, there is a concern that the base station 200 cannot notify the UE 100 of the TA for adjusting the uplink transmission timing for the cell C2 (TRP201#2) by the MAC CE. In an embodiment described later, a method for appropriately acquiring the TA by the MAC CE in order to adjust the uplink transmission timing for the cell C2 (TRP201#2) will be described.

[0064] (Configuration of user device) The configuration of the UE 100 according to the embodiment will be described with reference to Fig. 6. The UE 100 includes a communication unit 110 and a control unit 120.

[0065] The communication unit 110 performs wireless communication with the base station 200 by transmitting and receiving radio signals to and from the base station 200. The communication unit 110 has at least one transmission unit 111 and at least one reception unit 112. The transmission unit 111 and the reception unit 112 may be configured to include multiple antennas and RF circuits. The antenna converts a signal into radio waves and radiates the radio waves into space. The antenna also receives radio waves in space and converts the radio waves into a signal. The RF circuit performs analog processing of the signal transmitted and received via the antenna. The RF circuit may include a high-frequency filter, an amplifier, a modulator, a low-pass filter, etc.

[0066] The control unit 120 performs various controls in the UE 100. The control unit 120 controls communication with the base station 200 via the communication unit 110. The operations of the UE 100 described above and below may be controlled by the control unit 120. The control unit 120 may include at least one processor capable of executing a program and a memory that stores the program. The processor may execute the program to perform the operations of the control unit 120. The control unit 120 may include a digital signal processor that performs digital processing of signals transmitted and received via the antenna and the RF circuit. The digital processing includes processing of a RAN protocol stack. The memory stores programs executed by the processor, parameters related to the programs, and data related to the programs. The memory may include at least one of a read-only memory (ROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a random access memory (RAM), and a flash memory. All or a part of the memory may be included in the processor.

[0067] In one embodiment, the cell C1 (TRP201#1) and the cell C2 (TRP201#2) are configured in the UE 100 by the base station 200 that manages the cell C1 (TRP201#1) that is a serving cell and the cell C2 (TRP201#2) that belongs to the same frequency as the cell C1 (TRP201#1). The receiver 112 receives RA resource information from the cell C1 (TRP201#1) that indicates random access resources to be used in random access to the cell C2 (TRP201#2). The controller 120 determines a random access preamble to be transmitted in the random access using the RA resource information. The transmitter 111 transmits the determined random access preamble to the cell C1 (TRP201#1). The receiver 112 receives a response to the random access preamble from the base station 200, the response including a timing advance for adjusting the transmission timing of an uplink signal to the cell C2 (TRP201#2). This allows the UE 100 to appropriately acquire a timing advance for adjusting the transmission timing of the uplink signal to the cell C2 (TRP201#2) by random access. As a result, it becomes possible to appropriately control the transmission timing of the uplink signal to the cell C2 (TRP201#2).

[0068] In one embodiment, the cell C1 (TRP201#1) and the cell C2 (TRP201#2) are configured in the UE 100 by the base station 200 that manages the cell C1 (TRP201#1) that is a serving cell and the cell C2 (TRP201#2) that belongs to the same frequency as the cell C1 (TRP201#1). The receiving unit 112 receives a medium access control (MAC) control element from the base station (200), the medium access control (MAC) control element including a timing advance for adjusting the transmission timing of an uplink signal to the cell C2 (TRP201#2) and a cell identifier associated with the timing advance and uniquely identifying the cell C2 (TRP201#2). The control unit 120 identifies the cell C2 (TRP201#2) as a target cell for adjusting the transmission timing by the timing advance based on the cell identifier. As a result, the UE 100 can identify the target cell even if it transmits a TA by MAC CE, and can appropriately acquire a timing advance for adjusting the uplink transmission timing for the cell C2 (TRP201#2) by MAC CE. As a result, it becomes possible to appropriately control the transmission timing of the uplink signal for the cell C2 (TRP201#2).

[0069] (Base station configuration) The configuration of the base station 200 according to the embodiment will be described with reference to Fig. 7. The base station 200 includes a plurality of TRPs 201 (TRP 201#1 and TRP 201#2 in the example of Fig. 7), a communication unit 210, a network interface 220, and a control unit 230.

[0070] Each TRP 201 includes multiple antennas and is configured to be capable of beamforming. The TRP 201 may also be referred to as a panel or antenna panel. The antenna converts signals into radio waves and radiates the radio waves into space. The antenna also receives radio waves in space and converts the radio waves into signals. The TRPs 201 are distributed and each form a cell.

[0071] The communication unit 210 receives a radio signal from the UE 100 and transmits the radio signal to the UE 100, for example. The communication unit 210 has at least one transmission unit 211 and at least one reception unit 212. The transmission unit 211 and the reception unit 212 may be configured to include an RF circuit. The RF circuit performs analog processing of a signal transmitted and received via an antenna. The RF circuit may include a high-frequency filter, an amplifier, a modulator, a low-pass filter, etc.

[0072] The network interface 220 transmits and receives signals to and from the network. For example, the network interface 220 receives signals from adjacent base stations connected via an Xn interface, which is an interface between base stations, and transmits signals to the adjacent base stations. The network interface 220 also receives signals from the core network device 300 connected via an NG interface, and transmits signals to the core network device 300.

[0073] The control unit 230 performs various controls in the base station 200. The control unit 230 controls, for example, communication with the UE 100 via the communication unit 210. The control unit 230 also controls, for example, communication with a node (e.g., a neighboring base station, the core network device 300) via the network interface 220. The operations of the base station 200 described above and below may be operations controlled by the control unit 230. The control unit 230 may include at least one processor capable of executing a program and a memory that stores the program. The processor may execute the program to perform the operations of the control unit 230. The control unit 230 may include a digital signal processor that performs digital processing of signals transmitted and received via the antenna and the RF circuit. The digital processing includes processing of a protocol stack of the RAN. The memory stores the program executed by the processor, parameters related to the program, and data related to the program. All or a part of the memory may be included in the processor.

[0074] In one embodiment, the base station 200 (control unit 230) configures the UE 100 with a first cell (C1) that is a serving cell and a cell C2 (TRP201#2) that belongs to the same frequency as the first cell (C1). The transmitter 211 transmits, to the UE 100 in the first cell (C1), RA resource information indicating a random access resource to be used in random access to the cell C2 (TRP201#2). The receiver 112 receives, from the UE 100 in the cell C2 (TRP201#2), a random access preamble transmitted using the random access resource. The transmitter 211 transmits, to the UE 100, a response to the random access preamble that includes a timing advance for adjusting the transmission timing of an uplink signal to the cell C2 (TRP201#2). This enables the UE 100 to appropriately acquire a timing advance for adjusting the transmission timing of an uplink signal to the cell C2 (TRP201#2) by random access. As a result, it becomes possible to appropriately control the transmission timing of the uplink signal to the cell C2 (TRP201#2).

[0075] In one embodiment, the base station 200 (control unit 230) configures the UE 100 with a first cell (C1) that is a serving cell and a cell C2 (TRP201#2) that belongs to the same frequency as the first cell (C1). The control unit 230 generates a medium access control (MAC) control element (CE) that includes a timing advance for adjusting the transmission timing of an uplink signal to the cell C2 (TRP201#2) and a cell identifier that is associated with the timing advance and uniquely identifies the cell C2 (TRP201#2). The transmitter 211 transmits the MAC CE to the UE 100. As a result, the UE 100 can identify the target cell even when transmitting a TA using the MAC CE, and therefore can appropriately acquire a timing advance for adjusting the uplink transmission timing for the cell C2 (TRP201#2) using the MAC CE. As a result, the transmission timing of an uplink signal to the cell C2 (TRP201#2) can be appropriately controlled.

[0076] When the base station 200 is separated into the DU 202 and the CU 203, the communication unit 210 may be provided in the DU 202, and the control unit 230 may be provided in the DU 202 and / or the CU 203.

[0077] (System Operation) (1) First operation example 8 and 9, a first operation example in the mobile communication system 1 will be described. In the first operation example, the UE 100 adjusts the transmission timing of the uplink signal to the cell C2 based on group information indicating that the cell C1 (TRP201#1) and the cell C2 (TRP201#2) belong to the same timing advance group.

[0078] In step S101, the base station 200 (transmitter 211) transmits a first timing advance (first TA) for adjusting the transmission timing of an uplink signal to the cell C1 (TRP201#1) to the UE 100 in the cell C1 (TRP201#1). The UE 100 (receiver 112) receives the first TA from the cell C1 (TRP201#1).

[0079] The base station 200 (transmitter 211) may transmit the first TA by MAC CE, or may transmit the first TA by a response (RA response) to a random access (RA) preamble from the UE 100 in random access.

[0080] In step S102, the UE 100 (control unit 120) calculates a first adjustment value (T TA1 ) is determined. A first adjustment value (T TA1 ) to determine

[0081] The UE 100 (control unit 120) calculates the first TA (T A1 ) based on the first TA value (N TA1) to be assigned to the first TA value. TA,offset The UE 100 (control unit 120) may determine the first adjustment value (T TA1 ) may be determined.

[0082] The UE 100 (control unit 120) uses the downlink timing from the cell C1 (TRP201#1) as a timing reference for the first uplink transmission (hereinafter referred to as the first timing reference). As shown in FIG. 9, the UE 100 (control unit 120) adjusts the first adjustment value (T TA1 ) is determined as the first transmission timing.

[0083] In step S103, the UE 100 (transmitter 111) transmits the first uplink signal to the cell C1 (TRP 201#1) at the determined first transmission timing. The base station 200 (receiver 212) receives the uplink signal in the cell C1 (TRP 201#1).

[0084] Thereafter, the base station 200 (control unit 230) starts an operation for the UE 100 to perform data communication with the cell C2 (TRP 201#2) while maintaining the cell C1 (TRP 201#1) as the serving cell.

[0085] The base station 200 (control unit 230) determines whether the cell C1 (TRP201#1) and the cell C2 (TRP201#2) belong to the same timing advance group.

[0086] For example, the base station 200 (control unit 230) may determine that the cell C1 (TRP201#1) and the cell C2 (TRP201#2) belong to the same timing advance group when both of the following conditions (a) and (b) are satisfied. The base station 200 (control unit 230) may determine that the cell C1 (TRP201#1) and the cell C2 (TRP201#2) belong to different timing advance groups when at least one of the conditions (a) and (b) is not satisfied.

[0087] (a) A second adjustment value (T TA2 ) as the first TA is applicable (b) When adjusting the second transmission timing, the first timing reference can be used as the timing reference.

[0088] Based on the determination result, the base station 200 (control unit 230) generates group information indicating whether the cell C1 (TRP201#1) and the cell C2 (TRP201#2) belong to the same timing advance group. In the group information, for example, a timing advance group identifier may be set for each cell to indicate whether the cell C1 (TRP201#1) and the cell C2 (TRP201#2) belong to the same timing advance group. For example, if the group information associates the cell C1 (TRP201#1) with the timing advance group identifier #1 and associates the cell C2 (TRP201#2) with the timing advance group identifier #1, the group information may indicate that the cell C1 (TRP201#1) and the cell C2 (TRP201#2) belong to the same timing advance group. For example, if the group information associates cell C1 (TRP201#1) with timing advance group identifier #1 and associates cell C2 (TRP201#2) with timing advance group identifier #2, the group information may indicate that cell C1 (TRP201#1) and cell C2 (TRP201#2) belong to different timing advance groups. In this operation example, the explanation will proceed assuming that base station 200 (control unit 230) determines that cell C1 (TRP201#1) and cell C2 (TRP201#2) belong to the same timing advance group. Therefore, the group information indicates that cell C1 (TRP201#1) and cell C2 (TRP201#2) belong to the same timing advance group.

[0089] In step S104, the base station 200 (transmitter 211) transmits the group information in the cell C1 (TRP201#1) to the UE 100. The UE 100 (receiver 112) receives the group information from the cell C1 (TRP201#1).

[0090] The base station 200 (transmitter 211) may transmit group information to the UE 100 in the cell C1 (TRP201#1) during steps S1 to S4 in the procedure shown in FIG. 5 . The base station 200 (transmitter 211) may transmit, for example, configuration information including the group information and beam measurement configuration information for configuring a beam measurement reference signal to be used for beam measurement for the cell C2 (TRP201#2) to the UE 100. The UE 100 (receiver 112) receives the group information and the beam measurement configuration information from the cell C1 (TRP201#1). This allows the UE 100 to determine whether or not the second transmission timing can be adjusted using the first TA, as described below, before transmitting and receiving data to and from the cell C2 (TRP201#2) (i.e., step S4 in FIG. 5 ). Furthermore, signaling between the UE 100 and the base station 200 can be reduced compared to a case in which the group information and the beam measurement configuration information are transmitted separately.

[0091] The beam measurement setting information includes reference signal information indicating the SSB or channel state information reference signal (CSI-RS) transmitted by cell C2 (TRP201#2).

[0092] Note that the base station 200 (transmitter 211) may transmit the group information in the cell C2 (TRP201#2) to the UE 100. The UE 100 (receiver 112) may receive the group information from the cell C2 (TRP201#2).

[0093] The UE 100 (control unit 120) adjusts the transmission timing of the uplink signal to the cell C2 (TRP201#2) based on the group information. For example, the UE 100 performs the following operation.

[0094] In step S105, the UE 100 (control unit 120) determines, based on the group information, whether or not the cell C1 (TRP201#1) and the cell C2 (TRP201#2) belong to the same timing advance group.

[0095] In this operation example, UE100 (control unit 120) determines that cell C1 (TRP201#1) and cell C2 (TRP201#2) belong to the same timing advance group because the group information indicates that cell C1 (TRP201#1) and cell C2 (TRP201#2) belong to the same timing advance group.

[0096] In step S106, the UE 100 (control unit 120) determines a second adjustment value (T TA2 ) to determine

[0097] When the UE 100 (control unit 120) indicates that cell C1 (TRP201#1) and cell C2 (TRP201#2) belong to the same timing advance group, the UE 100 (control unit 120) may adjust the second transmission timing using the first TA. That is, the UE 100 (control unit 120) may determine the second adjustment value using the first TA. The UE 100 (control unit 120) may use the first adjustment value as the second adjustment value. This eliminates the need for the UE 100 to acquire a second timing advance (hereinafter, appropriately referred to as the second TA) different from the first TA from the base station 200, thereby reducing signaling between the UE 100 and the base station 200.

[0098] When determining the second adjustment value, the UE 100 (control unit 120) uses the first TA as the second TA and determines the second offset value (N TA,offset ) may use the first offset value determined in step S102. This allows UE 100 to omit the process of determining the second offset value using Table 1, for example. As a result, the processing load of UE 100 can be reduced.

[0099] 9, when the cell C1 (TRP201#1) and the cell C2 (TRP201#2) belong to the same timing advance group, the UE 100 (control unit 120) may adjust the second transmission timing using the first timing reference as the timing reference for the second uplink transmission (hereinafter referred to as the second timing reference as appropriate). Therefore, the UE 100 (control unit 120) may adjust the first transmission timing and the second transmission timing to be the same.

[0100] The UE 100 (control unit 120) may use the downlink timing from the cell C2 (TRP201#2) as the second timing reference. Therefore, the UE 100 (control unit 120) may use the determined second adjustment value (T TA2 ), i.e., the first adjustment value (T TA1 ) may be determined as the second transmission timing.

[0101] In this way, the UE 100 (control unit 120) adjusts the second transmission timing using the first TA.

[0102] The UE 100 (control unit 120) may manage the first TA value and the second TA value independently. That is, the UE 100 (control unit 120) may store the first TA value and the second TA value, respectively.

[0103] When the UE 100 (control unit 120) receives a first MAC CE including a first TA as a TA command from the base station 200, the UE 100 (control unit 120) may manage the first TA value based on the first MAC CE. That is, the UE 100 (control unit 120) updates the first TA value based on the first TA and stores the updated first TA value. On the other hand, when the UE 100 (control unit 120) receives a second MAC CE including a second TA as a TA command from the base station 200, the UE 100 (control unit 120) may manage the first TA value based on the first MAC CE. 2 The second TA value may be managed independently of the first TA value based on the MAC CE. The UE 100 (control unit 120) updates the second TA value based on the second TA and stores the updated second TA value.

[0104] Furthermore, the UE 100 (control unit 120) may manage the first adjustment value and the second adjustment value independently. The UE 100 (control unit 120) may manage information relating to adjustment of the transmission timing of the uplink signal independently for each cell.

[0105] Furthermore, when the first TA value is used as the second TA value, UE 100 (control unit 120) may store only the first TA value and not store the second TA value. Similarly, when the first adjustment value is used as the second adjustment value, UE 100 (control unit 120) may store only the first adjustment value and not store the second adjustment value.

[0106] In step S107, the UE 100 (transmitter 111) transmits the second uplink signal to the cell C2 (TRP201#2) at the determined second transmission timing. The base station 200 (receiver 212) receives the uplink signal in the cell C2 (TRP201#2).

[0107] When the UE 100 (control unit 120) receives a MAC CE including a first TA as a TA command from the base station 200, the UE 100 can adjust the second transmission timing in addition to the first transmission timing using the first TA.

[0108] (2) Second operation example 10 and 11, a second operation example in the mobile communication system 1 will be described, focusing on differences from the above-mentioned operation example. In the second operation example, a case will be described in which cell C1 (TRP201#1) and cell C2 (TRP201#2) belong to different timing advance groups.

[0109] The operations from step S111 to step S115 are the same as those in the above-described operation example. In this operation example, the base station 200 (control unit 230) generates group information indicating whether the cell C1 (TRP201#1) and the cell C2 (TRP201#2) belong to the same timing advance group. The base station 200 (control unit 230) transmits the generated group information to the UE 100 in the cell C1 (TRP201#1).

[0110] The UE 100 (control unit 120) determines, based on the group information, that the cell C1 (TRP201#1) and the cell C2 (TRP201#2) belong to different timing advance groups.

[0111] The UE 100 (control unit 120) may perform an operation to acquire the second TA. The UE 100 (control unit 120) may perform random access to, for example, cell C2 (TRP201#2). In the random access, the UE 100 (transmitting unit 111) may transmit a random access (RA) preamble to cell C2 (TRP201#2).

[0112] In step S116, the base station 200 (transmitter 211) transmits a second timing advance (second TA) for adjusting the second transmission timing to the UE 100 in the cell C1 (TRP201#1). The UE 100 (receiver 112) receives the second TA from the cell C1 (TRP201#1).

[0113] The base station 200 (transmitter 211) may transmit the second TA by MAC CE, or may transmit the second TA by a response (RA response) to a random access (RA) preamble from the UE 100 during random access. The UE 100 (receiver 112) may receive the second TA from the cell C2 (TRP201#2). Receiving the TA (second TA) used for transmitting the second uplink signal from the cell to which the second uplink signal is transmitted makes it easier to determine the TA to be applied.

[0114] In step S117, the UE 100 (control unit 120) calculates a second adjustment value (T TA2 ) to determine

[0115] The UE 100 (control unit 120) calculates the second TA (T A2 ) based on the second TA value (N TA2 ) is calculated.

[0116] The UE 100 (control unit 120) determines a second offset value (N TA,offset ) may be determined. The UE 100 (control unit 120) may use the first offset value determined when adjusting the first transmission timing as the second offset value. The UE 100 may determine the first TA value (N TA1 ) and the second TA value (N TA2 ) may be managed independently, and the first offset value may be used as the second offset value. This allows UE 100 to omit the process of determining the second offset value using Table 1, for example. As a result, the processing load of UE 100 can be reduced.

[0117] The UE100 (control unit 120) may (i) use the first offset value as the second offset value regardless of whether the first TA value and the second TA value are the same or not, (ii) use the first offset value as the second offset value regardless of whether the first adjustment value and the second adjustment value are the same or not, (iii) use the first offset value as the second offset value regardless of whether the first timing reference and the second timing reference are the same or not, or (iv) use the first offset value as the second offset value regardless of whether the transmission timing of the uplink signal after adjustment is the same or not. Therefore, when the cell C2 (TRP201#2) is configured together with the cell C1 (TRP201#1), the UE100 may assign the same offset value (N TA,offset ) can be applied.

[0118] The UE 100 (control unit 120) calculates a second adjustment value (T TA2 ) may be determined.

[0119] When the group information indicates that the cell C1 (TRP201#1) and the cell C2 (TRP201#2) belong to different timing advance groups, the UE 100 (control unit 120) may adjust the second transmission timing using the downlink timing from the cell C2 (TRP201#2) as the second timing reference. Specifically, as shown in FIG. 11, the UE 100 (control unit 120) may adjust the second transmission timing by using the determined second adjustment value (T TA2 ) as the second transmission timing. In this way, UE 100 (control unit 120) adjusts the second transmission timing using the second TA. This allows the network to flexibly set the second transmission timing of UE 100 (control unit 120).

[0120] The operation in step S118 is the same as the example of operation described above.

[0121] (3) Third operation example 12, a third operation example in the mobile communication system 1 will be described, focusing on differences from the above-described operation examples. In the third operation example, a case will be described in which the UE 100 adjusts the transmission timing of an uplink signal to cell C2 (TRP201#2) in response to activation of the TCI state. In this operation example, the UE 100 (control unit 120) adjusts the second transmission timing using the first TA.

[0122] The operations from step S201 to step S203 are the same as those in the above-described operation example.

[0123] In step S204, the base station 200 (transmitter 211) transmits an activation instruction to the UE 100 in the cell C1 (TRP201#1) to activate the TCI state associated with the cell C2 (TRP201#2). The UE 100 (receiver 112) receives the activation instruction from the cell C1 (TRP201#1). The activation instruction may include group information.

[0124] In response to receiving the activation instruction, UE 100 (control unit 120) activates the TCI state. Furthermore, in response to activating the TCI state, UE 100 (control unit 120) adjusts the second transmission timing of the uplink signal to cell C2 (TRP201#2). Therefore, in response to activating the TCI state, UE 100 (control unit 120) may start the following operation.

[0125] In step S205, UE 100 (control unit 120) determines whether cell C1 (TRP201#1) and cell C2 (TRP201#2) belong to the same timing advance group based on the group information, as in the above-described operation example. In this operation example, UE 100 (control unit 120) determines that cell C1 (TRP201#1) and cell C2 (TRP201#2) belong to the same timing advance group.

[0126] Alternatively, UE 100 (control unit 120) may determine whether to adjust the second transmission timing using the first TA or to adjust the second transmission timing using the second TA. In this operation example, UE 100 (control unit 120) determines to adjust the second transmission timing using the first TA.

[0127] Alternatively, the UE 100 (control unit 120) may perform the operation of adjusting the second transmission timing (that is, the operation of step S106 in the first operation example) using the first TA without making the above determination.

[0128] In step S206, the UE 100 (control unit 120) determines a second adjustment value (T TA2 That is, the UE 100 (control unit 120) adjusts the second transmission timing using the first TA.

[0129] The operation in step S207 is the same as the example of operation described above.

[0130] According to the above, the UE 100 can adjust the transmission timing of the uplink signal for the cell C2 (TRP201#2) at an appropriate opportunity. As a result, it is possible to appropriately control the transmission timing of the uplink signal for the cell C2 (TRP201#2).

[0131] (4) Fourth operation example 13 and 14, a fourth operation example in the mobile communication system 1 will be described, focusing on differences from the above-described operation examples. In the fourth operation example, similar to the third operation example, the UE 100 adjusts the transmission timing of the uplink signal to cell C2 (TRP201#2) in response to the activation of the TCI state. In this operation example, the UE 100 (control unit 120) adjusts the second transmission timing using the second TA.

[0132] 13, the operations from step S211 to step S215 are the same as those in the above-described operation example. In this operation example, UE 100 (control unit 120) determines that cell C1 (TRP201#1) and cell C2 (TRP201#2) belong to different timing advance groups. Also, in this operation example, UE 100 (control unit 120) may determine to adjust the second transmission timing using the second TA.

[0133] Alternatively, the UE 100 (control unit 120) may execute the subsequent operations without making the above determination.

[0134] When adjusting the second transmission timing using the second TA, UE100 (control unit 120) may determine whether or not the second TA is held. When the second TA is not held, UE100 (control unit 120) may execute the process of step S216. On the other hand, when the second TA is held, UE100 (control unit 120) may execute the process of step S218 without executing the process of step S216.

[0135] Here, the UE 100 (control unit 120) may hold a second adjustment timer (timeAlignmentTimer) that controls the time at which the transmission timing of the uplink signal to the cell C2 (TRP201#2) is considered to have been adjusted. For example, when the UE 100 (control unit 120) receives a second TA from the base station 200, the UE 100 (control unit 120) may start (or restart) the second adjustment timer.

[0136] The UE 100 (control unit 120) adjusts the second transmission timing using the second TA value within a predetermined time after receiving the second TA from the base station 200. The UE 100 (control unit 120) may measure the predetermined time using a second adjustment timer. When the second adjustment timer expires, the UE 100 (control unit 120) may retain the second TA value.

[0137] The UE 100 (control unit 120) may hold a first adjustment timer (timeAlignmentTimer) that controls the time at which the transmission timing of the uplink signal to the cell C1 (TRP201#1) is considered to have been adjusted.

[0138] In this operation example, the description will proceed assuming that UE 100 (control unit 120) does not hold the second TA value. If UE 100 (control unit 120) does not hold the second TA value when activating the TCI state, UE 100 (control unit 120) may perform random access (RA) to cell C2 (TRP201#2) to acquire the second TA. Therefore, UE 100 (control unit 120) may perform control to start the following operation. This allows UE 100 to acquire the second TA and calculate the second TA value.

[0139] In step S216, the UE 100 (transmitter 111) transmits an RA preamble to the cell C2 (TRP201#2). The base station 200 (receiver 212) receives the RA preamble in the cell C1 (TRP201#1). The RA preamble transmission is referred to as Msg1 in the RA procedure.

[0140] In response to receiving the RA preamble, the base station 200 (control unit 230) generates an RA response, and includes the second TA in the RA response.

[0141] The base station 200 (control unit 230) may allocate RA resources to be used for RA for the cell C2 (TRP201#2) to the UE 100. The base station 200 (transmission unit 211) may transmit information indicating the RA resources allocated to the UE 100 to the UE 100 in the cell C1 (TRP201#1) before step S216.

[0142] The RA resource may be a dedicated RA preamble that is assigned exclusively to the UE 100 from an RA preamble group prepared for the cell C2 (TRP201#2) and does not conflict with other UEs 100 in an RA for the cell C2 (TRP201#2). Alternatively, the RA resource may be one or more RA resources (CBRA preamble group) available for CBRA for the cell C2 (TRP201#2). A preamble included in the CBRA preamble group is an RA preamble that may conflict with other UEs 100.

[0143] In step S217, the base station 200 (transmitter 211) transmits an RA response to the UE 100 in the cell C1 (TRP201#1). Alternatively, the base station 200 (transmitter 211) may transmit the RA response to the UE 100 in the cell C2 (TRP201#2). The UE 100 (receiver 112) receives the RA response from the cell C1 (TRP201#1) or the cell C2 (TRP201#2). Note that the RA response transmission is referred to as Msg2 in the RA procedure.

[0144] The operations in steps S218 and S219 are the same as those in the above-described example of operation.

[0145] 14, in step S220, the base station 200 (transmitter 211) transmits a deactivation instruction to the UE 100 in the cell C1 (TRP201#1) to deactivate the TCI state associated with the cell C2 (TRP201#2). The UE 100 (receiver 112) receives the deactivation instruction from the cell C1 (TRP201#1).

[0146] In response to the deactivation instruction, the UE 100 (control unit 120) deactivates the TCI state associated with the cell C2 (TRP201#2).

[0147] In addition, the UE 100 (control unit 120) may regard the second adjustment timer as having expired in response to deactivating the TCI state. The UE 100 (control unit 120) may discard the second TA when the second adjustment timer has expired (or is deemed to have expired).

[0148] Step S221 is the same operation as step S214.

[0149] Step S222 is the same operation as step S215. UE 100 (control unit 120) may determine whether or not the second TA value is held. In this operation example, the description will proceed assuming that UE 100 (control unit 120) determines that the second TA value is held.

[0150] The UE 100 (control unit 120) does not execute the same process as the process of step S216, but executes the process of step S223.

[0151] Steps S223 and S224 are the same as in the above-described operation example.

[0152] The UE 100 (control unit 120) adjusts the second transmission timing by using the second TA value, which allows the UE 100 to omit an operation for acquiring the second TA, thereby reducing signaling between the UE 100 and the base station 200.

[0153] According to the above, the UE 100 can adjust the transmission timing of the uplink signal for the cell C2 (TRP201#2) at an appropriate opportunity. As a result, it is possible to appropriately control the transmission timing of the uplink signal for the cell C2 (TRP201#2).

[0154] (5) Fifth operation example 15, a fifth operation example in the mobile communication system 1 will be described, focusing on differences from the above-described operation examples. In this operation example, the UE 100 performs random access to the cell C2 (TRP201#2). The random access is contention-free random access (CFRA).

[0155] 15, in step S301, the base station 200 (transmitter 211) transmits cell identification information in the cell C1 (TRP201#1) to the UE 100. The UE 100 (receiver 112) receives the cell identification information from the cell C1 (TRP201#1).

[0156] The cell identification information is information for identifying the second cell. The cell identification information may include a cell identifier for identifying the second cell. The cell identifier may be used as an identifier indicating a transmission target of a random access (RA) preamble.

[0157] The cell identifier may be a physical cell identifier (PCI). Also, the cell identifier may be the radio network temporary identifier (RNTI) of the cell C2 (TRP201#2). The radio network temporary identifier (RNTI) of the cell C2 (TRP201#2) may be the cell radio network temporary identifier (C-RNTI) assigned to the UE 100. In this case, the C-RNTI (hereinafter, appropriately referred to as the second C-RNTI) of the cell C2 (TRP201#2) is different from the C-RNTI (hereinafter, appropriately referred to as the first C-RNTI) of the cell C1 (TRP201#1) assigned to the UE 100.

[0158] The cell identifier may be an index assigned to the cell C2 (TRP201#2) by the base station 200 (control unit 230). The index may be represented by a smaller number of bits than the PCI.

[0159] The cell identification information may be a list of cells managed by the base station 200 (control unit 230). The index assigned to the cell C2 (TRP201#2) by the base station 200 (control unit 230) may be implicitly notified to the UE 100 by the list of cells. For example, the index may be implicitly assigned to the cell in the order of the list of cells (for example, descending order). The UE 100 (control unit 120) may know the index (i.e., cell identifier) ​​of the cell C2 (TRP201#2) in the order of the cell C2 (TRP201#2) described in the list of cells.

[0160] The cell identification information may be included in the setting information for the cell C2. The setting information for the cell C2 includes the setting of the SSB used for beam measurement for the cell C2 (TRP201#2) and the setting required for using the radio resources for data transmission and reception (including data transmission and reception with the cell C2). Note that the cell identification information may be transmitted separately from the setting information for the cell C2.

[0161] Note that base station 200 (control unit 230) may omit transmitting cell identification information when PCI is included in the PDCCH command in step S302. Base station 200 (transmission unit 211) may transmit cell identification information (for example, C-RNTI) even when PCI is included in the PDCCH command in step S302.

[0162] Thereafter, the base station 200 (control unit 230) decides to have the UE 100 perform random access (RA) for the cell C2 (TRP201#2). The base station 200 (control unit 230) also decides random access (RA) resources to be used for the RA for the cell C2 (TRP201#2). In this operation example, the base station 200 (control unit 230) allocates a dedicated RA preamble to the UE 100 as the RA resource. The dedicated RA preamble is an RA preamble that is allocated exclusively to the UE 100 from among the RA preamble group prepared for the cell C2 (TRP201#2), and does not conflict with other UEs 100 in the RA for the cell C2 (TRP201#2).

[0163] In step S302, the base station 200 (transmitter 211) transmits a PDCCH command instructing the UE 100 to perform an RA for the cell C2 (TRP201#2) in the cell C1 (TRP201#1). For example, the base station 200 (transmitter 211) transmits downlink control information (DCI) of format 1_0 as a PDCCH command to the UE 100 on the PDCCH of the cell C1 (TRP201#1). The UE 100 (receiver 112) receives the PDCCH command. Note that the PDCCH command that causes the UE 100 to perform an RA for the cell C2 (TRP201#2) may be transmitted to the UE 100 in a manner different from the PDCCH command that causes the UE 100 to perform an RA for the cell C1 (TRP201#1).

[0164] The UE 100 (control unit 120) determines to perform RA based on the PDCCH command. The UE 100 (control unit 120) may understand that the PDCCH command instructs execution of RA for the cell C2 (TRP201#2) by including a cell identifier described later in the DCI.

[0165] The PDCCH command may include an index of a dedicated RA preamble to be used for RA for cell C2 (TRP201#2) as RA resource information indicating the RA resource. The dedicated RA preamble is the RA preamble assigned to UE 100 in step S301. UE 100 (receiving unit 112) receives the PDCCH command to receive RA resource information from cell C1 (TRP201#1). Since the PDCCH command includes the index of the dedicated RA preamble, UE 100 (control unit 120) can recognize the dedicated RA preamble together with an instruction to execute RA.

[0166] The UE 100 (control unit 120) determines an RA preamble to be transmitted in the RA using the RA resource information. In this operation example, the UE 100 (control unit 120) determines a dedicated RA preamble corresponding to the index of the dedicated RA preamble as the RA preamble to be transmitted in the RA.

[0167] The PDCCH command may include a cell identifier as an identifier indicating a transmission target of the RA preamble. The cell identifier included in the PDCCH command may be, for example, at least one of (a) an index assigned to cell C2 (TRP201#2) by base station 200, (b) a PCI of cell C2 (TRP201#2), and (c) a second C-RNTI. The cell identifier may be included in DCI format 1_0.

[0168] The UE 100 (control unit 120) may recognize the cell C2 (TRP201#2) indicated by the cell identifier as the transmission target of the RA preamble. The PDCCH command can specify the transmission target of the RA by including the cell identifier, and the UE 100 (control unit 120) can recognize the transmission target of the RA together with the instruction to execute the RA. Furthermore, the UE 100 (control unit 120) can recognize that the use target of the information notified by the DCI format 1_0 is the cell C2 (TRP201#2), even though the DCI format is from the cell C1 (TRP201#1). Furthermore, the UE 100 (control unit 120) can recognize the transmission target of the RA preamble when the number of TRP201 of the base station 200 is three or more.

[0169] In step S303, the UE 100 (transmitter 111) transmits the determined RA preamble (dedicated RA preamble) to the cell C2 (TRP201#2). The base station 200 (receiver 212) receives the dedicated RA preamble in the cell C2 (TRP201#2).

[0170] In response to receiving the RA preamble, the base station 200 (control unit 230) generates an RA response. The base station 200 (control unit 230) includes in the RA response a second TA for adjusting the second transmission timing to the cell C2 (TRP201#2).

[0171] In step S304, the base station 200 (transmitter 211) transmits an RA response including the second TA to the UE 100 in the cell C1 (TRP201#1). Alternatively, the base station 200 (transmitter 211) may transmit the RA response to the UE 100 in the cell C2 (TRP201#2). After transmitting the dedicated RA preamble, the UE 100 (receiver 112) receives the RA response from the cell C1 (TRP201#1) or the cell C2 (TRP201#2).

[0172] Step S305 is the same as the above-described example of operation.

[0173] As described above, the UE 100 can appropriately acquire the second TA by the CFRA in order to adjust the uplink transmission timing for the cell C2 (TRP201#2).

[0174] (6) Sixth operation example 16, a sixth operation example in the mobile communication system 1 will be described, focusing mainly on differences from the above-mentioned operation examples. Unlike the fifth operation example, this operation example is a case in which the PDCCH command does not include a cell identifier as an identifier indicating the transmission target of the RA preamble.

[0175] 16, in step S311, the base station 200 (control unit 230) assigns the cell radio network temporary identifier (1st C-RNTI) of the cell C1 (TRP201#1) to the UE 100 as the radio network temporary identifier (RNTI) of the cell C1 (TRP201#1). The base station 200 (transmission unit 211) transmits the 1st C-RNTI to the UE 100 in the cell C1 (TRP201#1). The UE 100 (reception unit 112) receives the 1st C-RNTI from the cell C1 (TRP201#1).

[0176] In step S312 , basis The base station 200 (control unit 230) assigns a second C-RNTI different from the first C-RNTI to the UE 100. The base station 200 (transmission unit 211) transmits the second C-RNTI to the UE 100 in the cell C1 (TRP201#1) as the above-mentioned cell identification information. The UE 100 (reception unit 112) receives the second C-RNTI from the cell C1 (TRP201#1).

[0177] Thereafter, similarly to the above-described operation example, the base station 200 (control unit 230) determines to have the UE 100 execute random access (RA) for the cell C2 (TRP201#2). In addition, the base station 200 (control unit 230) determines an RA resource to be used for the RA for the cell C2 (TRP201#2), and includes RA resource information indicating the determined RA resource in the PDCCH command.

[0178] Furthermore, the base station 200 (control unit 230) includes, in the PDCCH command, cyclic redundancy check (CRC) bits scrambled with the RNTI (2nd C-RNTI in this operation example) of the cell C2 (TRP201#2).

[0179] In step S313, base station 200 (transmitter 211) transmits a PDCCH command instructing UE 100 to perform RA for cell C2 (TRP201#2) in cell C1 (TRP201#1), similar to the above-described operation example. The PDCCH command does not need to include the above-described cell identifier. UE 100 (controller 120) can determine the transmission target of the RA preamble based on the second C-RNTI, even if the PDCCH command does not include a cell identifier, as shown below.

[0180] The UE 100 (control unit 120) determines whether or not the CRC bits included in the PDCCH command are scrambled with the second C-RNTI. If the UE 100 (control unit 120) can decode the CRC bits with the second C-RNTI, it determines that the CRC bits are scrambled with the second C-RNTI. On the other hand, if the UE 100 (control unit 120) cannot decode the CRC bits with the second C-RNTI, it determines that the CRC bits are not scrambled with the second C-RNTI.

[0181] When UE100 (control unit 120) determines that the CRC bits are scrambled with the second C-RNTI, it determines that the transmission target of the RA preamble is cell C2 (TRP201#2). In this case, UE100 (control unit 120) performs the same operation as the above-described operation example (step S302). On the other hand, when UE100 (control unit 120) determines that the transmission target of the RA preamble is not cell C2 (TRP201#2), it determines that the transmission target of the RA preamble is not cell C2 (TRP201#2).

[0182] In addition, when multiple cells (multiple TRP201) belonging to the same frequency as the serving cell, cell C1 (TRP201#1), are configured, UE100 (control unit 120) determines that the cell corresponding to the C-RNTI whose CRC bit can be decoded is the target to transmit the RA preamble.

[0183] The operations in steps S315 and S316 are the same as those in the above-described example of operation.

[0184] (7) Seventh operation example 17, a seventh operation example in the mobile communication system 1 will be described, focusing on differences from the above-described operation examples. In this operation example, the UE 100 performs contention based random access (CBRA) to the cell C2 (TRP201#2).

[0185] 17, in step S321, the base station 200 (transmitter 211) transmits configuration information for the cell C2, including RA resource information, to the UE 100 in the cell C1 (TRP201#1). The UE 100 (receiver 112) receives the configuration information for the cell C2 from the cell C1 (TRP201#1).

[0186] In this operation example, the RA resource information indicates one or more RA resources (CBRA preamble groups) available for CBRA for the cell C2 (TRP201#2). The CBRA preambles included in the CBRA preamble group are RA preambles that may conflict with other UEs 100.

[0187] In step S322, UE 100 (control unit 120) selects an RA preamble from one or more RA resources (CBRA preamble group) indicated by the RA resource information. UE 100 (control unit 120) may randomly select an RA preamble. UE 100 (control unit 120) determines the selected CBRA preamble as the RA preamble to be transmitted. This allows UE 100 to properly perform CBRA to obtain TA via RA.

[0188] In step S323, the UE 100 (transmitter 111) transmits the CBRA preamble determined as the RA preamble to be transmitted to the cell C2 (TRP201#2). The base station 200 (receiver 212) receives the CBRA preamble in the cell C2 (TRP201#2). In response to receiving the CBRA preamble, the base station 200 (controller 230) generates an RA response.

[0189] Steps S324 and S325 are the same as in the above-described operation example.

[0190] As described above, the UE 100 can appropriately acquire the second TA by the CBRA in order to adjust the uplink transmission timing for the cell C2 (TRP201#2).

[0191] (8) Eighth operation example 18 and 19, an eighth operation example in the mobile communication system 1 will be described, focusing mainly on differences from the above-described operation examples. In this operation example, the UE 100 acquires the second TA by the MAC CE.

[0192] As shown in FIG. 18, in step S401, the base station 200 (control unit 230) generates a MAC CE. The MAC CE may be a TRP-specific timing advance command MAC CE (hereinafter referred to as TRP-MAC CE as appropriate) as shown in FIG. 19. The TRP-MAC CE is a MAC CE that is different from a conventional timing advance command MAC CE. The TRP-MAC CE may be identified by a MAC subheader that has a logical channel identifier (LCID). The TRP-MAC CE may have a fixed size. The TRP-MAC CE may consist of a single octet.

[0193] The TRP-MAC CE includes a TA command as a second TA for adjusting the second transmission timing to cell C2 (TRP201#2) and a cell identifier that uniquely identifies cell C2 (TRP201#2). In the TRP-MAC CE, the cell identifier is an identifier associated with the second TA.

[0194] As shown in Figure 18, the cell identifier may be referred to as a TRP identifier (TRP ID). The TRP identifier may be, for example, an identifier of an addressed TRP provided by a cell different from cell C1 (TRP201#1) that has a PCI different from that of cell C1 (TRP201#1). Note that the TA command may be an index used to control the amount of timing adjustment that the MAC entity needs to apply.

[0195] Note that, similarly to the above-described fifth operation example, the base station 200 (control unit 230) may notify the UE 100 of the cell identifier by the cell identification information before transmitting the TRP-MAC CE. The base station 200 (control unit 230) may, for example, include the cell identification information (cell identifier) ​​in the setting information related to the cell C2.

[0196] The TRP-MAC CE may include an index for identifying the cell C2 (TRP201#2) as a cell identifier. Note that this index may be the index assigned to the cell C2 (TRP201#2) by the base station 200 (control unit 230), as described in the above-mentioned fifth operation example. When the cell identifier is this index, the UE 100 (receiving unit 112) receives this index from the base station 200 before receiving the TRP-MAC CE. The UE 100 (receiving unit 112) may receive configuration information related to the cell C2 including this index before receiving the TRP-MAC CE.

[0197] Furthermore, the TRP-MAC CE may include the radio network temporary identifier (RNTI) of the cell C2 (TRP201#2) as the cell identifier. The RNTI of the cell C2 (TRP201#2) may be, for example, the second C-RNTI described in the fifth operation example above. When the cell identifier is the RNTI of the cell C2 (TRP201#2), the UE 100 (receiving unit 112) has received the RNTI (for example, the second C-RNTI) of the cell C2 (TRP201#2) before receiving the TRP-MAC CE.

[0198] Furthermore, the TRP-MAC CE may use a physical cell identifier (PCI) as the cell identifier.

[0199] Note that the conventional timing advance command MAC CE includes a timing advance group identifier (TAG ID) but does not include a cell identifier.

[0200] In step S402, the base station 200 (transmitter 211) transmits the MAC CE to the UE 100 in the cell C1 (TRP201#1). Alternatively, the base station 200 (transmitter 211) may transmit the MAC CE to the UE 100 in the cell C2 (TRP201#2). The UE 100 (receiver 112) receives the MAC CE from the cell C1 (TRP201#1) or the cell C2 (TRP201#2).

[0201] Based on the cell identifier included in the TRP-MAC CE, the UE 100 (control unit 120) identifies the cell C2 (TRP201#2) as a target cell for adjusting the transmission timing by the TA (i.e., the second TA) indicated by the TA command.

[0202] The operations in steps S403 and S404 are the same as those in the above-described example of operation.

[0203] (Other embodiments) The operational sequences (and operational flows) in the above-described embodiments do not necessarily have to be executed in chronological order according to the order depicted in the flow diagrams or sequence diagrams. For example, the steps in the operations may be executed in an order different from that depicted in the flow diagrams or sequence diagrams, or may be executed in parallel. Some of the steps in the operations may be deleted, or additional steps may be added to the processing. The operational sequences (and operational flows) in the above-described embodiments may be executed independently, or two or more operational sequences (and operational flows) may be executed in combination. For example, some steps in one operational flow may be added to another operational flow, or some steps in one operational flow may be replaced with some steps in another operational flow.

[0204] In the above-described embodiment, an NR-based mobile communication system has been described as an example of the mobile communication system 1. However, the mobile communication system 1 is not limited to this example. The mobile communication system 1 may be a system compliant with a TS of either LTE or another generation system (e.g., 6th generation) of the 3GPP standard. The base station 200 may be an eNB that provides E-UTRA user plane and control plane protocol termination for the UE 100 in LTE. The mobile communication system 1 may be a system compliant with a TS of a standard other than the 3GPP standard. The base station 200 may be an IAB (Integrated Access and Backhaul) donor or an IAB node.

[0205] A program may be provided that causes a computer to execute each process performed by the UE 100 or the base station 200. The program may be recorded on a computer-readable medium. Using the computer-readable medium, the program can be installed on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM. Furthermore, circuits that execute each process performed by the UE 100 or the base station 200 may be integrated, and at least a part of the UE 100 or the base station 200 may be configured as a semiconductor integrated circuit (chip set, SoC).

[0206] In the above embodiments, "transmit" may mean performing processing at least one layer in a protocol stack used for transmission, or may mean physically transmitting a signal wirelessly or via a wired connection. Alternatively, "transmit" may mean a combination of performing processing at least one layer and physically transmitting a signal wirelessly or via a wired connection. Similarly, "receive" may mean performing processing at least one layer in a protocol stack used for reception, or may mean physically receiving a signal wirelessly or via a wired connection. Alternatively, "receive" may mean a combination of performing processing at least one layer and physically receiving a signal wirelessly or via a wired connection. Similarly, "obtain / acquire" may mean obtaining information from stored information, obtaining information from information received from another node, or obtaining information by generating the information. Similarly, "include" and "comprise" do not mean including only the enumerated items, but may mean including only the enumerated items or including additional items in addition to the enumerated items. Similarly, in this disclosure, "or" does not mean an exclusive or, but rather a logical or.

[0207] The above describes the embodiments in detail with reference to the drawings, but the specific configuration is not limited to that described above, and various design changes can be made within the scope that does not deviate from the gist of the invention. [Explanation of symbols]

[0208] 100:UE 110: Communications Department 111: Transmitter 112: Receiving unit 120: Control unit 200:Base station 210: Communications Department 211: Transmission unit 212: Receiving unit 220: Network Interface 230: Control unit 300: Core network equipment C1, C2: Cells

Claims

1. A communication device (100), a receiving unit (112) that receives, from a base station (200), radio resource control (RRC) signaling including first information for setting a list of physical cell identifiers including a second physical cell identifier different from a first physical cell identifier of a serving cell, and second information for setting resources used to transmit a random access preamble based on information for indicating the second physical cell identifier, and receives, from the base station (200), a downlink control information format used for a physical downlink control channel (PDCCH) command instructing execution of a random access procedure; When the downlink control information format includes information for indicating the second physical cell identifier included in the list of physical cell identifiers corresponding to transmission of the random access preamble, transmitting the random access preamble using resources configured based on the second information; a control unit (120) that executes transmission of a random access preamble corresponding to the first physical cell identifier when the downlink control information format includes information for indicating the first physical cell identifier corresponding to transmission of the random access preamble. Communication equipment.

2. the receiving unit (112) receives information for setting an identifier of a first timing advance group and an identifier of a second timing advance group from the base station (200), and receives a random access response from the base station (200) based on transmission of the random access preamble; The control unit (120) controls a timing adjustment value for uplink transmission in the second timing advance group based on a timing advance command corresponding to the second timing advance group included in the random access response. The communication device according to claim 1 .

3. The receiving unit (112) receives the first information and setting information including information for setting an SS / PBCH Block (SSB) from the base station (200), The control unit (120) performs measurements based on the information for setting up the SSB.

3. The communication device according to claim 1 or 2.

4. The receiving unit (112) receives the downlink control information format including information for indicating the second physical cell identifier corresponding to the transmission of the random access preamble from the base station (100) in the serving cell.

3. The communication device according to claim 1 or 2.

5. A base station (200), a transmitter (211) that transmits, to a communication device (100), radio resource control (RRC) signaling including first information for setting a list of physical cell identifiers including a second physical cell identifier different from a first physical cell identifier of a serving cell, and second information for setting resources used to transmit a random access preamble based on information for indicating the second physical cell identifier, and transmits, to the communication device (100), a downlink control information format used in a physical downlink control channel (PDCCH) command instructing execution of a random access procedure; When the downlink control information format includes information for indicating the second physical cell identifier included in the list of physical cell identifiers corresponding to the transmission of the random access preamble, the random access preamble is received from the communication device (100) using resources set based on the second information; a receiving unit (212) that receives a random access preamble corresponding to the first physical cell identifier from the communication device (100) when information for indicating the first physical cell identifier corresponding to transmission of the random access preamble is included in the downlink control information format. Base station.

6. the transmitting unit (211) transmits information for setting an identifier of a first timing advance group and an identifier of a second timing advance group to the communication device (100), and transmits a random access response to the communication device (100) based on reception of the random access preamble; a timing adjustment value for uplink transmission in the second timing advance group is controlled based on a timing advance command corresponding to the second timing advance group included in the random access response; The base station according to claim 5.

7. The transmitting unit (211) transmits the first information and setting information including information for setting an SS / PBCH Block (SSB) to the communication device (200).

7. The base station according to claim 5 or 6.

8. The transmitting unit (211) transmits the downlink control information format including information for indicating the second physical cell identifier corresponding to the transmission of the random access preamble to the communication device (200) in the serving cell.

7. The base station according to claim 5 or 6.

9. A communication method executed in a communication device (100), comprising: receiving, from a base station (200), radio resource control (RRC) signaling including first information for configuring a list of physical cell identifiers including a second physical cell identifier different from a first physical cell identifier of a serving cell, and second information for configuring resources used to transmit a random access preamble based on information for indicating the second physical cell identifier; and receiving, from the base station (200), a downlink control information format used in a physical downlink control channel (PDCCH) command instructing execution of a random access procedure; transmitting the random access preamble using resources configured based on the second information when the downlink control information format includes information indicating the second physical cell identifier included in the list of physical cell identifiers corresponding to transmission of the random access preamble; transmitting a random access preamble corresponding to the first physical cell identifier when the downlink control information format includes information indicating the first physical cell identifier corresponding to transmission of the random access preamble. Communication method.

10. receiving information for setting a first timing advance group identifier and a second timing advance group identifier from the base station (200); and receiving a random access response from the base station (200) based on the transmission of the random access preamble; and controlling a timing adjustment value for uplink transmissions in the second timing advance group based on a timing advance command corresponding to the second timing advance group included in the random access response. The communication method according to claim 9.

11. receiving the first information and configuration information including information for configuring an SS / PBCH Block (SSB) from the base station (200); and performing measurements based on the information to configure the SSB. The communication method according to claim 9 or 10.

12. In the step of receiving the downlink control information format, the downlink control information format including information for indicating the second physical cell identifier corresponding to the transmission of the random access preamble is received from the base station (200) in the serving cell. The communication method according to claim 9 or 10.

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