Communication device, base station, and communication method

Abstract

To provide a base station that appropriately controls 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 100 in which a first cell C1 and a second cell C2 are set by a base station 200 that manages a serving cell and the second cell C2 includes: a control unit that adjusts first transmission timing, which is transmission timing of an uplink signal to the first cell C1, and second transmission timing, which is transmission timing of an uplink signal to the second cell; and a transmission unit that transmits the uplink signal to the first cell C1 at the first transmission timing and transmits the uplink signal to the second cell C2 at the second transmission timing. The control unit stops transmission of the uplink signal to the second cell C2 when a difference between the first transmission timing and the second transmission timing exceeds an allowable maximum value.SELECTED DRAWING: Figure 18

Description

Technical Field

[0001] The present invention relates to a user device and a communication method used in a mobile communication system.

Background Art

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

[0003] In a scenario of multi-TRP transmission, a first cell serving as a serving cell and a second cell belonging to the same frequency (intra-frequency) as the first cell are set in a user device, and a model is assumed in which the user device maintains the first cell as a serving cell while performing data communication with the second cell (see Non-Patent Documents 1 to 3). Here, the second cell is a cell having a different TRP from the first cell and a physical cell identifier (PCI) different from that of the first cell.

[0004] By the way, a user device located far from a cell transmits an uplink signal at an earlier timing compared to a user device located close to the cell in order to compensate for propagation delay. Specifically, the user device adjusts the transmission timing of the uplink signal based on the timing advance from the base station.

Prior Art Documents

Non-Patent Documents

[0005]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the above-described plurality of TRP transmission scenarios, it is considered necessary for the user equipment to perform uplink signal transmission timing adjustment 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 uplink signal transmission timing for the second cell cannot be appropriately controlled.

[0007] Therefore, an object of the present invention is to provide a user equipment and a communication method capable of appropriately controlling the uplink signal transmission timing for a second cell when a first cell that is a serving cell and a second cell belonging to the same frequency as the first cell are set.

Means for Solving the Problems

[0008] The user equipment (100) according to the first aspect is a user equipment (100) in which a first cell (C1) serving as a serving cell and a second cell (C2) belonging to the same frequency as the first cell (C1) are set by a base station (200) that manages the first cell (C1) and the second cell (C2). The user equipment includes a control unit (120) that adjusts a first transmission timing that is a transmission timing of an uplink signal to the first cell (C1) and a second transmission timing that is a transmission timing of an uplink signal to the second cell (C2), and a transmission unit (111) that transmits an uplink signal to the first cell (C1) at the first transmission timing and transmits an uplink signal to the second cell (C2) at the second transmission timing. When a difference between the first transmission timing and the second transmission timing exceeds an allowable maximum value, the control unit (120) stops transmission of an uplink signal to the second cell (C2).

[0009] The communication method according to the second aspect is a communication method executed by a user equipment (100) in which a first cell (C1) serving as a serving cell and a second cell (C2) belonging to the same frequency as the first cell (C1) are set by a base station (200) that manages the first cell (C1) and the second cell (C2). The communication method includes a step of adjusting a first transmission timing that is a transmission timing of an uplink signal to the first cell (C1) and a second transmission timing that is a transmission timing of an uplink signal to the second cell (C2), a step of transmitting an uplink signal to the first cell (C1) at the first transmission timing and transmitting an uplink signal to the second cell (C2) at the second transmission timing, and a step of stopping transmission of an uplink signal to the second cell (C2) when a difference between the first transmission timing and the second transmission timing exceeds an allowable maximum value.

Advantages of the Invention

[0010] According to one aspect of the present invention, there can be provided a user equipment and a communication method capable of appropriately controlling the transmission timing of an uplink signal with respect to a second cell when a first cell serving as a serving cell and a second cell belonging to the same frequency as the first cell are set.

Brief Description of Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Embodiments for Carrying Out the Invention

[0012] The mobile communication system according to the 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.

[0013] (Configuration of the Mobile Communication System) With reference to FIG. 1, the configuration of the mobile communication system 1 according to the embodiment will be described. The mobile communication system 1 is a system compliant with, for example, the technical specifications (Technical Specification: TS) of 3GPP. Hereinafter, as the mobile communication system 1, a fifth-generation system (5th Generation System: 5GS) of the 3GPP standard, that is, a mobile communication system based on NR (New Radio) will be taken as an example for description.

[0014] The mobile communication system 1 includes a network 10 and a user equipment (UE) 100 that communicates with the network 10. The network 10 includes an NG-RAN (Next Generation Radio Access Network) 20 which is a 5G radio access network and a 5GC (5G Core Network) 30 which is a 5G core network.

[0015] UE100 is a device used by a user. UE100 is a movable device such as, for example, a mobile phone terminal such as a smartphone, a tablet terminal, a notebook PC, a communication module, or a communication card. UE100 may be a vehicle (e.g., a car, a train, etc.) or a device provided thereon. UE100 may be a transport aircraft other than a vehicle (e.g., a ship, an airplane, etc.) or a device provided thereon. UE100 may be a sensor or a device provided thereon. Note that UE100 may be called by another name 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.

[0016] NG-RAN20 includes a plurality of 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 constituted by one component carrier. The term "cell" may represent a radio communication resource or may represent a communication target of UE100. Each base station 200 can perform radio communication with UE100 present in its cell. The base station 200 communicates with UE100 using the protocol stack of the RAN. The base station 200 provides NR user plane and control plane protocol terminations towards UE100 and is connected to 5GC30 via the NG interface. Such an NR base station 200 may be referred to as a gNodeB (gNB).

[0017] 5GC30 includes a core network device 300. The core network device 300 includes, for example, an AMF (Access and Mobility Management Function) and / or a UPF (User Plane Function). The AMF performs mobility management of UE100. The UPF provides a function specialized for user plane processing. The AMF and the UPF are connected to the base station 200 via the NG interface.

[0018] Referring to FIG. 2, a configuration example of a protocol stack in the mobile communication system 1 according to the embodiment will be described.

[0019] The protocol for the radio section between the UE 100 and the base station 200 has a physical (PHY) layer, a MAC (Medium Access Control) layer, an RLC (Radio Link Control) layer, a PDCP (Packet Data Convergence Protocol) layer, and an RRC (Radio Resource Control) layer.

[0020] The PHY layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Between the PHY layer of the UE 100 and the PHY layer of the base station 200, data and control information are transmitted via a physical channel.

[0021] The physical channel is composed of a plurality of OFDM symbols in the time domain and a plurality of subcarriers in the frequency domain. One subframe is composed of a plurality of OFDM symbols in the time domain. A resource block is a resource allocation unit and is composed of a plurality of OFDM symbols and a plurality of subcarriers. A frame can be composed of 10 ms and can include 10 subframes composed of 1 ms. The number of slots corresponding to the subcarrier interval can be included in a subframe.

[0022] Among the physical channels, the physical downlink control channel (PDCCH) plays a central role, for example, for purposes such as downlink scheduling assignment, uplink scheduling grant, and transmission power control.

[0023] In NR, the UE 100 can use a bandwidth narrower than the system bandwidth (i.e., the cell bandwidth). The base station 200 sets a bandwidth part (BWP) consisting of consecutive PRBs for the UE 100. The UE 100 transmits and receives data and control signals in the active BWP. Up to, for example, four BWPs can be set for the UE 100. Each BWP may have a different subcarrier spacing or may have overlapping frequencies. When multiple BWPs are set for the UE 100, the base station 200 can specify which BWP to activate by means of downlink control. Thereby, the base station 200 can dynamically adjust the UE bandwidth according to the amount of UE 100 data traffic, etc., and can reduce UE power consumption.

[0024] The base station 200 can set up to three control resource sets (CORESETs) for each of up to four BWPs on the serving cell, for example. A CORESET is a radio resource for control information that the UE 100 should receive. Up to 12 CORESETs can be set for the UE 100 on the serving cell. Each CORESET has an index from 0 to 11. For example, a CORESET is composed of six resource blocks (PRBs) and one, two, or three consecutive OFDM symbols in the time domain.

[0025] The MAC layer performs priority control of data, retransmission processing by hybrid automatic repeat request (HARQ), and random access procedures, etc. Data and control information are transmitted between the MAC layer of the UE 100 and the MAC layer of the base station 200 via a transport channel. The MAC layer of the base station 200 includes a scheduler. The scheduler determines the transport format (transport block size, modulation and coding scheme (MCS)) for the uplink and downlink and the resources allocated to the UE 100.

[0026] The RLC layer transmits data to the RLC layer on the receiving side by utilizing the functions of the MAC layer and the PHY layer. Between the RLC layer of the UE100 and the RLC layer of the base station 200, data and control information are transmitted via logical channels.

[0027] The PDCP layer performs header compression / expansion and encryption / decryption.

[0028] An SDAP (Service Data Adaptation Protocol) layer may be provided as the upper layer of the PDCP layer. The SDAP (Service Data Adaptation Protocol) layer performs the mapping between the IP flow, which is the unit for the core network to perform QoS control, and the radio bearer, which is the unit for the AS (Access Stratum) to perform QoS control.

[0029] The RRC layer controls the logical channel, transport channel, and physical channel in response to the establishment, re - establishment, and release of radio bearers. Between the RRC layer of the UE100 and the RRC layer of the base station 200, RRC signaling for various settings is transmitted. When there is an RRC connection between the RRC of the UE100 and the RRC of the base station 200, the UE100 is in the RRC connected state. When there is no RRC connection between the RRC of the UE100 and the RRC of the base station 200, the UE100 is in the RRC idle state. When the RRC connection between the RRC of the UE100 and the RRC of the base station 200 is suspended, the UE100 is in the RRC inactive state.

[0030] The NAS layer located above the RRC layer performs session management and mobility management of the UE100. Between the NAS layer of the UE100 and the NAS layer of the core network device 300 (AMF), NAS signaling is transmitted. Note that the UE100 has an application layer etc. in addition to the protocol of the radio interface.

[0031] (Method for Adjusting Uplink Transmission Timing) Referring to FIG. 3, an example of a method for adjusting uplink transmission timing in the mobile communication system 1 according to the embodiment will be described. That is, a method for synchronizing uplink transmission timing will be described.

[0032] The base station 200 controls the uplink signal transmission timing of each UE 100 in order to keep the reception timing of the uplink signal from each UE 100 within a predetermined time range in the cell it manages. The base station 200 determines a timing advance (hereinafter, TA) for the UE 100 to adjust the uplink signal transmission timing. The base station 200 provides the determined TA to each UE 100.

[0033] The UE 100 adjusts the uplink transmission timing with reference to the downlink frame timing. The UE 100 uses TA to adjust the uplink frame timing with respect to the downlink frame. As shown in FIG. 4, the UE 100 advances the i-th uplink frame by the time of (N TA +N TA,offset )T c with respect to the i-th downlink frame. The UE 100 calculates an adjustment value (T TA ) for shifting with respect to the downlink frame using, for example, the following formula.

[0034]

Equation

[0035] N TA is a value (appropriately referred to as a TA value) calculated based on the TA (T A ) notified from the base station 200 (cell). N TA can be calculated by Equations 2 and 3.

[0036] The TA (T A ) in Equation 2 is the value of the timing advance command (TA command) included in the medium access control (MAC) control element (CE). The UE 100, in response to receiving the TA command, updates the held TA value (N TA_old ) to a new TA value (NTA_NEW ) is calculated. In Equation 3, TA(T A ) is the value of the timing advance included in the random access response. Note that μ is the subcarrier spacing setting.

[0037] N TA,offset is a fixed offset value used to calculate the adjustment value (T TA ). N TA,offset may be notified from the base station 200 (cell). If UE100 is not notified of N TA,offset , it may determine N TA,offset as a default value. UE100 may determine the offset value (N TA,offset ) according to conditions such as the frequency band, the presence or absence of MR-DC, and the presence or absence of coexistence of NR·NB-IoT. UE100 may determine the offset value (N TA,offset ), for example, using Table 1 below.

[0038]

Table 1

[0039] T c is the basic time unit. T c is a predetermined fixed value. UE100 holds the information of T c in advance. T c is, for example, 0.509 ns.

[0040] The downlink frame timing that serves as a reference for adjusting the uplink transmission timing is the timing at the start of the downlink frame. Specifically, the downlink frame timing is defined as the time when the first path detected (within the time) in the downlink frame is received from the base station 200 (specifically, the reference cell). Note that the radio frames constituting the uplink frame and the downlink frame are composed of 10 1-ms subframes. Each frame is divided into two half-frames of the same size consisting of 5 subframes.

[0041] UE100 uses the synchronization signal included in the reference signal (SSB: SS / PBCH Block) transmitted in the BWP to perform downlink timing synchronization, thereby being able to grasp the downlink frame timing in the BWP where the SSB is received.

[0042] Note that the SSB includes a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a PBCH (Physical Broadcast Channel), and a demodulation reference signal (DMRS). For example, the SSB may be composed of four consecutive OFDM symbols in the time domain. Also, the SSB may be composed of 240 consecutive subcarriers (i.e., 20 resource blocks) in the frequency domain. The PBCH is a physical channel that carries the master information block (MIB).

[0043] (Assumed Scenario) Referring to FIG. 4, an assumed scenario in the mobile communication system 1 according to the embodiment will be described.

[0044] The base station 200 includes a TRP201#1, a TRP201#2, a DU (Distributed Unit) 202, and a CU (central unit) 203. In FIG. 4, an example where the base station 200 is separated into the DU202 and the CU203 is shown, but the base station 200 may not be separated into the DU202 and the CU203. Also, an example where the number of TRPs 201 of the base station 200 is two is shown, but the number of TRPs 201 of the base station 200 may be three or more.

[0045] The TRP201#1 and the TRP201#2 are distributed and configured to form different cells. Specifically, the TRP201#1 forms cell C1, and the TRP201#2 forms cell C2.

[0046] Cell C1 and cell C2 belong to the same frequency. The physical cell identifiers (PCIs) of cell C1 and cell C2 are different from each other. That is, cell C2 is a cell having a TRP different from TRP201#1 corresponding to cell C1 and having a PCI different from that of cell C1. In FIG. 4, an example where the coverage of cell C2 is within the coverage of cell C1 is shown, but the coverage of cell C2 only needs to overlap at least partially with the coverage of cell C1.

[0047] DU202 controls TRP201#1 and TRP201#2. In other words, TRP201#1 and TRP201#2 are under the same DU202. DU202 is a unit including lower layers included in the above protocol stack, for example, the RLC layer, the MAC layer, and the PHY layer. DU202 is connected to CU203 via the F1 interface which is a fronthaul interface.

[0048] CU203 controls DU202. CU203 is a unit including upper layers included in the above protocol stack, for example, the RRC layer, the SDAP layer, and the PDCP layer. CU203 is connected to the core network (5GC30) via the NG interface which is a backhaul interface.

[0049] UE100 is in the RRC connected state and performs wireless communication with the base station 200. NR enables broadband transmission in a high-frequency band such as the millimeter-wave band. In order to compensate for the radio wave attenuation in the radio waves of such a high-frequency band, beamforming is utilized between the base station 200 and UE100 to obtain a high beam gain. The base station 200 and UE100 establish a beam pair.

[0050] UE100 is serving CellIt performs data communication with cell C1 (TRP201#1). Specifically, UE100 performs data communication with cell C1 using the beam corresponding to transmission configuration indicator (TCI) state #1. In addition to cell C1, cell C 2, which is a non-serving cell, is configured for UE100. For example, for UE100, an SSB (SS / PBCH Block) for performing beam measurement for cell C2, and C radio resources for performing data communication with cell

[0051] 2 are configured from cell C1. UE100 reports the result of beam measurement for cell C2 to cell C1. The base station 200 (DU202) receives the beam measurement result from UE100 in cell C1, and activates TCI state #2 corresponding to the beam of cell C2 based on the beam measurement result.

[0052] Thus, in the embodiment, in the scenario of multi-TRP transmission, cell C1, which is the serving cell, and cell C2 belonging to the same frequency (intra-frequency) as cell C1 are configured for UE100, and a model is assumed in which UE100 performs data communication with cell C2 while maintaining cell C1 as the serving cell.

[0053] Referring to FIG. 5, the basic procedure in the assumed scenario according to the embodiment will be described.

[0054] In step S1, UE100 receives configuration information from cell C1 (TRP201#1) by, for example, RRC signaling. The configuration information includes the configuration of the SSB used for beam measurement for cell C2 (TRP201#2) and the configuration necessary for using radio resources for data transmission and reception (including data transmission and reception with cell C2). The configuration information may be transmitted from CU203 to UE100 via DU202 and cell C1 (TRP201#1).

[0055] In step S2, UE100 performs beam measurement on cell C2 (TRP201#2) using the configuration information (especially, SSB configuration) received in step S1 (step S2a), and transmits a report including the measurement results to cell C1 (TRP201#1) (step S2b). DU202 receives the beam measurement results via cell C1 (TRP201#1).

[0056] In step S3, DU202 transmits an instruction to activate the TCI state associated with cell C2 (TRP201#2) to UE100 via cell C1 (TRP201#1) based on the beam measurement results received in step S2. 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.

[0057] In step S4, UE100 transmits and receives data with cell C2 (TRP201#2) using the UE-dedicated channel on cell C2 (TRP201#2). DU202 transmits and receives data with UE100 via cell C2 (TRP201#2).

[0058] Note that UE100 is within the coverage of cell C1 (TRP201#1) and receives the broadcast channel (BCCH) and paging channel (PCH), which are common channels, from cell C1 (TRP201#1).

[0059] According to such a scenario and procedure, without relying on a handover instruction from a higher layer (especially the RRC layer), and without performing a handover from cell C1 (TRP201#1) to cell C2 (TRP201#2), UE100 can switch data communication from cell C1 (TRP201#1) to cell C2 (TRP201#2) through beam management in layer 1 (PHY layer) and layer 2 (MAC layer, etc.). That is, the cell for data communication can be realized by beam switching in layer 1 (PHY layer) and layer 2 (MAC layer, etc.).

[0060] In the above scenario, it is considered necessary for UE100 to perform uplink signal transmission timing adjustment for each of cell C1 (TRP201#1) and cell C2 (TRP201#2). However, a method for adjusting the uplink transmission timing for cell C2 (TRP201#2) has not been realized, and there is a concern that the uplink signal transmission timing for cell C2 (TRP201#2) cannot be appropriately controlled. In an embodiment described later, a method for enabling appropriate control of the uplink signal transmission timing for cell C2 (TRP201#2) will be described.

[0061] Also, in the above scenario, it is assumed that the uplink signal transmission timing for cell C1 (TRP201#1) (the first transmission timing) is different from the uplink signal transmission timing for cell C2 (TRP201#2) (the second transmission timing). Here, within the range of the transmission window provided on the transmission circuit side of UE100, uplink simultaneous transmission can be performed on multiple carriers. When the difference between the first transmission timing and the second transmission timing is large, there is a concern that uplink simultaneous transmission to cell C1 (TRP201#1) and cell C2 (TRP201#2) cannot be accommodated within the range of the transmission window, and the uplink signal transmission cannot be appropriately executed. In an embodiment described later, when a first cell that is a serving cell and a second cell belonging to the same frequency as the first cell are set, a method for enabling appropriate control of the uplink signal transmission will be described.

[0062] (Configuration of User Equipment) With reference to FIG. 6, the configuration of UE 100 according to the embodiment will be described. UE 100 includes a communication unit 110 and a control unit 120.

[0063] 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 includes 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 a plurality of antennas and RF circuits. The antenna converts a signal into a radio wave and radiates the radio wave into space. Also, the antenna receives a radio wave in space and converts the radio wave into a signal. The RF circuit performs analog processing of signals transmitted and received via the antenna. The RF circuit may include a high-frequency filter, an amplifier, a modulator, a low-pass filter, and the like.

[0064] The control unit 120 performs various controls in the UE 100. The control unit 120 controls the communication with the base station 200 via the communication unit 110. The operations of the UE 100 described above and below may be operations under the control of the control unit 120. The control unit 120 may include at least one processor capable of executing a program and a memory for storing 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 RF circuits. The digital processing includes the processing of the RAN protocol stack. Note that the memory stores the program executed by the processor, the parameters related to the program, and the data related to the program. The memory may include at least one of ROM (Read Only Memory), EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory), RAM (Random Access Memory), and flash memory. All or part of the memory may be included in the processor.

[0065] In one embodiment, for the UE 100, the base station 200 that manages the serving cell, cell C1 (TRP201#1), and cell C2 (TRP201#2) belonging to the same frequency as cell C1 (TRP201#1) sets cell C1 (TRP201#1) and cell C2 (TRP201#2). The control unit 120 adjusts a first transmission timing that is the transmission timing of the uplink signal to cell C1 (TRP201#1) and a second transmission timing that is the transmission timing of the uplink signal to cell C2 (TRP201#2). The transmission unit 111 transmits the uplink signal to cell C1 (TRP201#1) at the first transmission timing and transmits the uplink signal to cell C2 (TRP201#2) at the second transmission timing. When the difference between the first transmission timing and the second transmission timing exceeds the maximum allowable value, the control unit (120) stops the transmission of the uplink signal to cell C2 (TRP201#2).

[0066] As a result, when the transmission of the uplink signal to cell C1 (TRP201#1) and the transmission of the uplink signal to cell C2 (TRP201#2) do not fall within the range of the transmission window and there is a possibility that the uplink signal cannot be transmitted to cell C1 (TRP201#1) at the first transmission timing, by stopping the transmission of the uplink signal to cell C2 (TRP201#2), First the uplink signal can be transmitted to cell C1 (TRP201#1) at the transmission timing. By such an operation, the transmission timing of the uplink signal to cell C2 (TRP201#2) can be appropriately controlled. As a result, when cell C1 (TRP201#1) which is a serving cell and cell C2 (TRP201#2) belonging to the same frequency as the cell C1 (TRP201#1) are set, the transmission of the uplink signal can be appropriately controlled. above the uplink signal can be transmitted. By such an operation, the transmission timing of the uplink signal to cell C2 (TRP201#2) can be appropriately controlled. As a result, when cell C1 (TRP201#1) which is a serving cell and cell C2 (TRP201#2) belonging to the same frequency as the cell C1 (TRP201#1) are set, the transmission of the uplink signal can be appropriately controlled.

[0067] (Configuration of Base Station) With reference to FIG. 7, the configuration of the base station 200 according to the embodiment will be described. The base station 200 includes a plurality of TRPs 201 (in the example of FIG. 7, TRP201#1 and TRP201#2), a communication unit 210, a network interface 220, and a control unit 230.

[0068] Each TRP 201 includes a plurality of antennas and is configured to be capable of beamforming. The TRP 201 may be referred to as a panel or an antenna panel. The antenna converts a signal into a radio wave and radiates the radio wave into space. Also, the antenna receives a radio wave in space and converts the radio wave into a signal. Each TRP 201 is dispersedly arranged and constitutes a cell respectively.

[0069] The communication unit 210 receives, for example, a radio signal from the UE 100 and transmits a radio signal to the UE 100. The communication unit 210 includes 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 signals transmitted and received via an antenna. The RF circuit may include a high-frequency filter, an amplifier, a modulator, a low-pass filter, and the like.

[0070] The network interface 220 transmits and receives signals to and from the network. The network interface 220 receives, for example, a signal from an adjacent base station connected via an Xn interface which is a base station interface, and transmits a signal to the adjacent base station. Also, the network interface 220 receives, for example, a signal from a core network device 300 connected via an NG interface, and transmits a signal to the core network device 300.

[0071] 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. Also, the control unit 230 controls, for example, communication with nodes (for example, an adjacent 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 under the control of the control unit 230. The control unit 230 may include at least one processor capable of executing a program and a memory storing 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 an antenna and an RF circuit. The digital processing includes processing of the RAN protocol stack. Note that the memory stores a program executed by the processor, parameters related to the program, and data related to the program. All or part of the memory may be included in the processor.

[0072] In addition, 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.

[0073] (System operation) (1) First operation example Referring to FIGS. 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 the group information indicating that the cell C1 (TRP 201#1) and the cell C2 (TRP 201#2) belong to the same timing advance group.

[0074] In step S101, the base station 200 (transmission unit 211) transmits a first timing advance (first TA) for adjusting the transmission timing of the uplink signal to the cell C1 (TRP 201#1) to the UE 100 in the cell C1 (TRP 201#1). The UE 100 (reception unit 112) receives the first TA from the cell C1 (TRP 201#1).

[0075] The base station 200 (transmission unit 211) may transmit the first TA by means of a MAC CE, or may transmit it by means of a response (RA response) to a random access (RA) preamble from the UE 100 in random access.

[0076] In step S102, the UE 100 (control unit 120) determines a first adjustment value (T TA1 ). The UE 100 (control unit 120) determines a first adjustment value (T TA1 ) for adjusting the transmission timing (hereinafter, appropriately referred to as the first transmission timing) of the uplink signal to the cell C1 (TRP 201#1) (hereinafter, appropriately referred to as the first uplink signal).

[0077] The UE 100 (control unit 120) determines, for example, a first TA value (N A1 ) based on the first TA (T TA1 using Equation 2 or Equation 3.Calculate it. Also, the UE 100 (control unit 120) may determine a first offset value (N TA,offset ) to be added to the first TA value. The UE 100 (control unit 120) may use the above formula 1 to determine a first adjustment value (T TA1 ) based on the first TA value and the determined first offset value.

[0078] The UE 100 (control unit 120) uses the downlink timing from cell C1 (TRP201#1) as the timing reference for the first uplink transmission (hereinafter, appropriately referred to as the first timing reference). As shown in FIG. 9, the UE 100 (control unit 120) determines the timing shifted by the first adjustment value (T TA1 ) determined from the first timing reference as the first transmission timing.

[0079] In step S103, the UE 100 (transmission unit 111) transmits a first uplink signal to cell C1 (TRP201#1) at the determined first transmission timing. The base station 200 (reception unit 212) receives the uplink signal in cell C1 (TRP201#1).

[0080] After that, the base station 200 (control unit 230) starts an operation for performing data communication with cell C2 (TRP201#2) while the UE 100 maintains cell C1 (TRP201#1) as a serving cell.

[0081] The base station 200 (control unit 230) determines whether cell C1 (TRP201#1) and cell C2 (TRP201#2) belong to the same timing advance group.

[0082] The base station 200 (control unit 230) may determine that cell C1 (TRP201#1) and cell C2 (TRP201#2) belong to the same timing advance group if, for example, both of the following conditions (a) and (b) are satisfied. The base station 200 (control unit 230) may determine that cell C1 (TRP201#1) and cell C2 (TRP201#2) belong to different timing advance groups if at least one of conditions (a) and (b) is not satisfied.

[0083] (a) When the first TA can be applied as the second adjustment value (T TA2 ) for adjusting the transmission timing of the uplink signal to cell C2 (TRP201#2) (hereinafter appropriately referred to as the second uplink signal) (hereinafter appropriately referred to as the second transmission timing) (b) When the first timing reference can be used as the timing reference when adjusting the second transmission timing

[0084] The base station 200 (control unit 230) generates group information indicating whether cell C1 (TRP201#1) and cell C2 (TRP201#2) belong to the same timing advance group based on the determination result. In the group information, for example, by setting a timing advance group identifier for each cell, it may indicate whether cell C1 (TRP201#1) and cell C2 (TRP201#2) belong to the same timing advance group. For example, in the group information, if cell C1 (TRP201#1) is associated with a timing advance group identifier #1 and cell C2 (TRP201#2) is associated with the timing advance group identifier #1, the group information may indicate that cell C1 (TRP201#1) and cell C2 (TRP201#2) belong to the same timing advance group. For example, in the group information, if cell C1 (TRP201#1) is associated with a timing advance group identifier #1 and cell C2 (TRP201#2) is associated with a 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 description will proceed assuming that the 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.

[0085] In step S104, the base station 200 (transmission unit 211) transmits the group information to the UE100 in cell C1 (TRP201#1). The UE100 (reception unit 112) receives the group information from cell C1 (TRP201#1).

[0086] The base station 200 (transmission unit 211) may transmit group information to the UE 100 in the cell C1 (TRP201#1) between step S1 and step S4 in the procedure shown in FIG. 5. The base station 200 (transmission unit 211) may transmit, for example, setting information including the group information and beam measurement setting information for setting a beam measurement reference signal used for beam measurement for the cell C2 (TRP201#2) to the UE 100. The UE 100 (reception unit 112) receives the group information and the beam measurement setting information from the cell C1 (TRP201#1). Thereby, before data transmission and reception between the UE 100 and the cell C2 (TRP201#2) (that is, step S4 in FIG. 5), it is possible to determine whether the second transmission timing can be adjusted using the first TA as described later. Also, compared with the case where the group information and the beam measurement setting information are transmitted separately, the signaling between the UE 100 and the base station 200 can be reduced.

[0087] The beam measurement setting information includes reference signal information indicating an SSB or a channel state information reference signal (CSI-RS) transmitted by the cell C2 (TRP201#2).

[0088] Note that the base station 200 (transmission unit 211) may transmit the group information to the UE 100 in the cell C2 (TRP201#2). The UE 100 (reception unit 112) may receive the group information from the cell C2 (TRP201#2).

[0089] 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 operations.

[0090] In step S105, the UE 100 (control unit 120) determines whether the cell C1 (TRP201#1) and the cell C2 (TRP201#2) belong to the same timing advance group based on the group information.

[0091] In this operation example, since the group information indicates that cell C1 (TRP201#1) and cell C2 (TRP201#2) belong to the same timing advance group, UE100 (control unit 120) determines that cell C1 (TRP201#1) and cell C2 (TRP201#2) belong to the same timing advance group.

[0092] In step S106, UE100 (control unit 120) determines a second adjustment value (T TA2 ) for adjusting the second transmission timing.

[0093] If it is shown that cell C1 (TRP201#1) and cell C2 (TRP201#2) belong to the same timing advance group, UE100 (control unit 120) may adjust the second transmission timing using the first TA. That is, UE100 (control unit 120) may determine the second adjustment value using the first TA. UE100 (control unit 120) may use the first adjustment value as the second adjustment value. Thereby, since UE100 does not need to obtain a second timing advance (hereinafter appropriately referred to as the second TA) different from the first TA from the base station 200, the signaling between UE100 and the base station 200 can be reduced.

[0094] When determining the second adjustment value, UE100 (control unit 120) may use the first TA as the second TA and use the first offset value determined in step S102 as the second offset value (N TA,offset ). Thereby, UE100 can omit the process of determining the second offset value using, for example, Table 1. As a result, the processing load on UE100 can be reduced.

[0095] As shown in FIG. 9, when the UE 100 (control unit 120) indicates that the cell C1 (TRP 201#1) and the cell C2 (TRP 201#2) belong to the same timing advance group, the UE 100 (control unit 120) may use the first timing reference as the timing reference for the second uplink transmission (hereinafter appropriately referred to as the second timing reference) to adjust the second transmission timing. Therefore, the UE 100 (control unit 120) may have the same first transmission timing and second transmission timing.

[0096] Note that the UE 100 (control unit 120) may use the downlink timing from the cell C2 (TRP 201#2) as the second timing reference. Therefore, the UE 100 (control unit 120) may determine the second transmission timing by shifting the determined second adjustment value (T TA2 ), that is, the first adjustment value (T TA1 ) by the second adjustment value (T

[0097] In this way, the UE 100 (control unit 120) adjusts the second transmission timing using the first TA.

[0098] Note that 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.

[0099] When the UE 100 (control unit 120) receives the first MAC CE including the 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 the second MAC CE including the second TA as a TA command from the base station 200, the UE 100 (control unit 120) may manage the second TA value independently of the first TA value based on the second 2 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.

[0100] Further, 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 regarding the adjustment of the transmission timing of the uplink signal independently for each cell.

[0101] Also, when the UE 100 (control unit 120) uses the first TA value as the second TA value, it may store only the first TA value and not store the second TA value. Similarly, when the UE 100 (control unit 120) uses the first adjustment value as the second adjustment value, it may store only the first adjustment value and not store the second adjustment value.

[0102] In step S107, the UE 100 (transmission unit 111) transmits the second uplink signal to cell C2 (TRP201#2) at the determined second transmission timing. The base station 200 (reception unit 212) receives the uplink signal in cell C2 (TRP201#2).

[0103] Note that when the UE 100 (control unit 120) receives a MAC CE including the first TA from the base station 200 as a TA command, it can adjust the second transmission timing in addition to the first transmission timing using the first TA.

[0104] (2) Second operation example With reference to FIGS. 10 and 11, the second operation example in the mobile communication system 1 will be mainly described in terms of differences from the above-described operation example. In the second operation example, a case where cell C1 (TRP201#1) and cell C2 (TRP201#2) belong to different timing advance groups will be described.

[0105] The operations from step S111 to step S115 are the same as those in the above-described operation example. Note that in this operation example, the base station 200 (control unit 230) generates group information indicating whether cell C1 (TRP201#1) and 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 cell C1 (TRP201#1).

[0106] UE100 (control unit 120) determines, based on the group information, that cell C1 (TRP201#1) and cell C2 (TRP201#2) belong to different timing advance groups.

[0107] UE100 (control unit 120) may perform an operation to obtain the second TA. UE100 (control unit 120) may, for example, perform a random access to cell C2 (TRP201#2). In the random access, UE100 (transmission unit 111) may transmit a random access (RA) preamble to cell C2 (TRP201#2).

[0108] In step S116, base station 200 (transmission unit 211) transmits a second timing advance (second TA) for adjusting the second transmission timing to UE100 in cell C1 (TRP201#1). UE100 (reception unit 112) receives the second TA from cell C1 (TRP201#1).

[0109] Base station 200 (transmission unit 211) may transmit the second TA by means of a MAC CE, or may transmit it by means of a response (RA response) to a random access (RA) preamble from UE100 in the random access. UE100 (reception unit 112) may receive the second TA from cell C2 (TRP201#2). By receiving the TA (second TA) used for transmitting the second uplink signal from the cell to which the second uplink signal is to be transmitted, it is easier to grasp the TA to be applied.

[0110] In step S117, UE100 (control unit 120) determines a second adjustment value (T TA2 ) for adjusting the second transmission timing.

[0111] UE100 (control unit 120) calculates, for example, a second TA value (N A2 ) based on the second TA (T TA2 ) using the above-described equation 2 or equation 3.

[0112] UE100 (control unit 120) may determine a second offset value (N TA,offset ) to be assigned to the second TA value. UE100 (control unit 120) may use the first offset value determined when adjusting the first transmission timing as the second offset value. While independently managing the first TA value (N TA1 ) and the second TA value (N TA2 ), UE100 may use the first offset value as the second offset value. Thereby, UE100 can, for example, omit the process of determining the second offset value using Table 1. As a result, the processing load on UE100 can be reduced.

[0113] UE100 (control unit 120) may use the first offset value as the second offset value regardless of (i) whether the first TA value and the second TA value are the same, (ii) whether the first adjustment value and the second adjustment value are the same, (iii) whether the first timing reference and the second timing reference are the same, or (iv) whether the transmission timing of the adjusted uplink signal is the same. Therefore, when cell C2 (TRP201#2) is set together with cell C1 (TRP201#1), UE100 can apply the same offset value (N TA,offset ) to both cells.

[0114] UE100 (control unit 120) may determine a second adjustment value (T TA2 ) based on the calculated second TA value and the determined second offset value using Equation 1 above.

[0115] When the group information indicates that cell C1 (TRP201#1) and cell C2 (TRP201#2) belong to different timing advance groups, the UE100 (control unit 120) may adjust the second transmission timing using the downlink timing from cell C2 (TRP201#2) as the second timing reference. Specifically, as shown in FIG. 11, the UE100 (control unit 120) determines the second transmission timing as the timing shifted by the determined second adjustment value (T TA2 ) from the second timing reference. In this way, the UE100 (control unit 120) adjusts the second transmission timing using the second TA. Thereby, the network can flexibly set the second transmission timing of the UE100 (control unit 120).

[0116] The operation of step S118 is the same as the above-described operation example.

[0117] (3) Third operation example Referring to FIG. 12, differences from the above-described operation example will be mainly described for the third operation example in the mobile communication system 1. In the third operation example, a case where the transmission timing of the uplink signal to cell C2 (TRP201#2) is adjusted in response to the activation of the TCI state by the UE100 will be described. In this operation example, the UE100 (control unit 120) adjusts the second transmission timing using the first TA.

[0118] The operations from step S201 to step S203 are the same as the above-described operation example.

[0119] In step S204, the base station 200 (transmission unit 211) transmits an activation instruction for activating the TCI state associated with cell C2 (TRP201#2) to the UE100 in cell C1 (TRP201#1). The UE100 (reception unit 112) receives the activation instruction from cell C1 (TRP201#1). Note that the activation instruction may include group information.

[0120] UE100 (control unit 120) activates the TCI state in response to receiving an activation instruction. Further, UE100 (control unit 120) adjusts the second transmission timing of the uplink signal to cell C2 (TRP201#2) in response to activating the TCI state. Therefore, UE100 (control unit 120) may start the following operations in response to activating the TCI state.

[0121] In step S205, UE100 (control unit 120) determines, based on the group information, whether cell C1 (TRP201#1) and cell C2 (TRP201#2) belong to the same timing advance group, in the same manner as in the above operation example. 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.

[0122] Alternatively, UE100 (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, UE100 (control unit 120) determines to adjust the second transmission timing using the first TA.

[0123] Alternatively, UE100 (control unit 120) may execute an operation of adjusting the second transmission timing using the first TA (i.e., the operation of step S106 in the first operation example) without performing the above determination.

[0124] In step S206, UE100 (control unit 120) determines a second adjustment value (T TA2 ) for adjusting the second transmission timing, in the same manner as in the above operation example. That is, UE100 (control unit 120) adjusts the second transmission timing using the first TA.

[0125] The operation of step S207 is the same as in the above operation example.

[0126] According to the above, the UE 100 can adjust the transmission timing of the uplink signal for cell C2 (TRP201#2) at an appropriate opportunity. As a result, the transmission timing of the uplink signal for cell C2 (TRP201#2) can be appropriately controlled.

[0127] (4) Fourth operation example With reference to FIGS. 13 and 14, the fourth operation example in the mobile communication system 1 will be mainly described in terms of differences from the above-described operation examples. In the fourth operation example, similarly to the third operation example, the transmission timing of the uplink signal to cell C2 (TRP201#2) is adjusted in response to the activation of the TCI state by the UE 100. In this operation example, the UE 100 (control unit 120) adjusts the second transmission timing using the second TA.

[0128] In FIG. 13, the operations from step S211 to step S215 are the same as those in the above-described operation examples. In this operation example, the 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, the UE 100 (control unit 120) may determine to adjust the second transmission timing using the second TA.

[0129] Alternatively, the UE 100 (control unit 120) may execute the subsequent operations without performing the above determination.

[0130] When the UE 100 (control unit 120) adjusts the second transmission timing using the second TA, it may determine whether it holds the second TA. When the UE 100 (control unit 120) does not hold the second TA, it may execute the process of step S216. On the other hand, when the UE 100 (control unit 120) holds the second TA, it may execute the process of step S218 without executing the process of step S216.

[0131] Here, the UE 100 (control unit 120) may hold a second adjustment timer (timeAlignmentTimer) that controls the time when it is considered that the transmission timing of the uplink signal to cell C2 (TRP201#2) has been adjusted. For example, when the UE 100 (control unit 120) receives the second TA from the base station 200, it may start (or restart) the second adjustment timer.

[0132] Within a predetermined time after the UE 100 (control unit 120) receives the second TA from the base station 200, it adjusts the second transmission timing using the second TA value. The UE 100 (control unit 120) may measure the predetermined time using the second adjustment timer. When the second adjustment timer expires, the UE 100 (control unit 120) may hold the second TA value.

[0133] Note that the UE 100 (control unit 120) may also hold a first adjustment timer (timeAlignmentTimer) that controls the time when it is considered that the transmission timing of the uplink signal to cell C1 (TRP201#1) has been adjusted.

[0134] In this operation example, the description will proceed on the assumption that the UE 100 (control unit 120) does not hold the second TA value. When the UE 100 (control unit 120) does not hold the second TA value when activating the TCI state, it may perform a random access (RA) to cell C2 (TRP201#2) in order to acquire the second TA. Therefore, the UE 100 (control unit 120) may perform control to start the following operations. As a result, the UE 100 can acquire the second TA and calculate the second TA value.

[0135] In step S216, the UE 100 (transmission unit 111) transmits an RA preamble to cell C2 (TRP201#2). The base station 200 (reception unit 212) receives the RA preamble in cell C1 (TRP201#1). Note that the RA preamble transmission is referred to as Msg1 in the RA procedure.

[0136] The base station 200 (control unit 230) generates an RA response in response to the reception of an RA preamble. The base station 200 (control unit 230) includes a second TA in the RA response.

[0137] Note that the base station 200 (control unit 230) may allocate to the UE 100 the RA resources to be used for the RA for the cell C2 (TRP201#2). The base station 200 (transmission unit 211) may transmit to the UE 100 in the cell C1 (TRP201#1) information indicating the RA resources allocated to the UE 100 before step S216.

[0138] The RA resources, the dedicated RA preamble, may be dedicatedly allocated to the UE 100 from among the RA preamble groups prepared for the cell C2 (TRP201#2), and may be RA preambles that do not conflict with other UEs 100 in the RA for the cell C2 (TRP201#2). Alternatively, the RA resources may be one or more RA resources (CBRA preamble groups) available for the CBRA for the cell C2 (TRP201#2). The preambles included in the CBRA preamble groups are RA preambles that may conflict with other UEs 100.

[0139] In step S217, the base station 200 (transmission unit 211) transmits the RA response to the UE 100 in the cell C1 (TRP201#1). Alternatively, the base station 200 (transmission unit 211) may transmit the RA response to the UE 100 in the cell C2 (TRP201#2). The UE 100 (reception unit 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.

[0140] The operations in steps S218 and S219 are the same as those in the above-described operation example.

[0141] As shown in FIG. 14, in step S220, the base station 200 (transmission unit 211) transmits a deactivation instruction for deactivating the TCI state associated with cell C2 (TRP201#2) to the UE 100 in cell C1 (TRP201#1). The UE 100 (reception unit 112) receives the deactivation instruction from cell C1 (TRP201#1).

[0142] The UE 100 (control unit 120) deactivates the TCI state associated with cell C2 (TRP201#2) in response to the deactivation instruction.

[0143] Note that the UE 100 (control unit 120) may consider that the second adjustment timer has 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 (is considered to have expired).

[0144] Step S221 is the same operation as step S214.

[0145] Step S222 is the same operation as step S215. The UE 100 (control unit 120) may determine whether it is holding the second TA value. In this operation example, the description will proceed assuming that the UE 100 (control unit 120) has determined that it is holding the second TA value.

[0146] The UE 100 (control unit 120) executes the process of step S223 without executing the same process as that of step S216.

[0147] Steps S223 and S224 are the same as the above-described operation example.

[0148] The UE 100 (control unit 120) adjusts the second transmission timing using the second TA value. Thereby, the UE 100 can omit the operation for acquiring the second TA, and the signaling between the UE 100 and the base station 200 can be reduced.

[0149] According to the above, the UE 100 can perform the transmission timing adjustment of the uplink signal for the cell C2 (TRP201#2) at an appropriate opportunity. As a result, the transmission timing of the uplink signal for the cell C2 (TRP201#2) can be appropriately controlled.

[0150] (5) Fifth operation example With reference to FIGS. 15 and 16, the fifth operation example in the mobile communication system 1 will be mainly described with differences from the above-described operation examples.

[0151] In FIG. 15, the TCI state associated with the cell C2 (TRP201#2) is activated.

[0152] In step S301, the base station 200 (transmission unit 211) transmits, to the UE 100 in the cell C1 (TRP201#1), first resource information indicating a first resource related to the transmission of an uplink signal to the cell C1 (TRP201#1) and second resource information indicating a second resource related to the transmission of an uplink signal to the cell C2 (TRP201#2). Alternatively, the base station 200 (transmission unit 211) may transmit the first resource information to the UE 100 in the cell C1 (TRP201#1) and transmit the second resource information to the UE 100 in the cell C2 (TRP201#2). The UE 100 (reception unit 112) receives the first resource information and the second resource information from the cell C1 (TRP201#1). The UE 100 (reception unit 112) may receive the first resource information from the cell C1 (TRP201#1) and receive the second resource information from the cell C2 (TRP201#2).

[0153] The first resource and the second resource are physical uplink control channel (PUCCH) configuration information for configuring the PUCCH for the UE 100, sounding reference signal (SRS) configuration information for configuring the SRS for the UE 100, a downlink allocation allocated for downlink transmission to the UE 100, an uplink grant allocated for uplink transmission to the UE 100, and semi-permanent channel state information report(It may include at least any one of the PUSCH resources for the report of CSI).

[0154] In step S302, the UE 100 (transmission unit 111) transmits a first uplink signal to cell C1 (TRP201#1) at a first transmission timing. Also, the UE 100 (transmission unit 111) transmits a second uplink signal to cell C2 (TRP201#2) at a second transmission timing.

[0155] The UE 100 (control unit 120) holds a first adjustment timer and a second adjustment timer. The first adjustment timer (timeAlignmentTimer) is a timer that controls the time considered for the transmission timing of the uplink signal to cell C1 (TRP201#1) to be adjusted. The second adjustment timer (timeAlignmentTimer) is a timer that controls the time considered for the transmission timing of the uplink signal to cell C2 (TRP201#2) to be adjusted.

[0156] As shown in FIG. 16, in step S311, the UE 100 (control unit 120) determines whether the first adjustment timer has expired. If the first adjustment timer has expired, the UE 100 (control unit 120) executes the process of step S312. If the first adjustment timer has not expired, the UE 100 (control unit 120) executes the process of step S314.

[0157] In step S312, the UE 100 (control unit 120) releases the first resource. As an operation of releasing the first resource, the UE 100 (control unit 120) may execute the following operations.

[0158] The UE 100 (control unit 120) may flush all hybrid ARQ (HARQ) buffers for cell C1 (TRP201#1) in the MAC layer.

[0159] When the PUCCH configuration information for cell C1 (TRP201#1) is set, UE100 (control unit 120) may notify the RRC layer to release the PUCCH configuration information for cell C1 (TRP201#1) in the MAC layer. UE100 (control unit 120) may release the PUCCH configuration information in response to the notification in the RRC layer.

[0160] UE100 (control unit 120) for cell C1 (TRP201#1) SRS When the configuration information is set, UE100 (control unit 120) may notify the RRC layer to release the SRS configuration information for cell C1 (TRP201#1) in the MAC layer. UE100 (control unit 120) may release the SRS configuration information in response to the notification in the RRC layer.

[0161] UE100 (control unit 120) may erase the downlink allocation for cell C1 (TRP201#1) in the MAC layer. UE100 (control unit 120) may erase the uplink grant for cell C1 (TRP201#1) in the MAC layer. UE100 (control unit 120) may erase the PUSCH resource for semi-persistent CSI reporting for cell C1 (TRP201#1) in the MAC layer.

[0162] UE100 (control unit 120) may hold the first TA value (N A1 ) calculated based on the first TA (T TA1 ).

[0163] In step S313, UE100 (control unit 120) releases the second resource. UE100 (control unit 120) may perform the following operations as the operation of releasing the second resource.

[0164] UE100 (control unit 120) may flush all hybrid ARQ (HARQ) buffers for cell C2 (TRP201#2) in the MAC layer.

[0165] When the PUCCH configuration information for cell C2 (TRP201#2) is configured, UE100 (control unit 120) may notify the RRC layer to release the PUCCH configuration information for cell C2 (TRP201#2) in the MAC layer. UE100 (control unit 120) may release the PUCCH configuration information in response to the notification in the RRC layer.

[0166] UE100 (control unit 120) SRS When the configuration information for cell C2 (TRP201#2) is configured, UE100 (control unit 120) may notify the RRC layer to release the SRS configuration information for cell C2 (TRP201#2) in the MAC layer. UE100 (control unit 120) may release the SRS configuration information in response to the notification in the RRC layer.

[0167] UE100 (control unit 120) may cancel the downlink allocation for cell C2 (TRP201#2) in the MAC layer. UE100 (control unit 120) may cancel the uplink grant for cell C2 (TRP201#2) in the MAC layer. UE100 (control unit 120) may cancel the PUSCH resource for semi-persistent CSI reporting for cell C2 (TRP201#2) in the MAC layer.

[0168] UE100 (control unit 120) A2 may hold the second TA value (N TA2 ) calculated based on the second TA (T

[0169] In step S314, UE100 (control unit 120) determines whether the second adjustment timer has expired. If the second adjustment timer has expired, UE100 (control unit 120) executes the process of step S312. If the second adjustment timer has not expired, UE100 (control unit 120) may end the process.

[0170] According to the above, when the first adjustment timer expires, the UE 100 (control unit 120) releases the first resource and also releases the second resource. Thereby, when the first resource is released, the second resource is also released, so that communication with the cell C2 (TRP201#2) where a problem may occur is no longer performed. Therefore, when communication with the cell C2 (TRP201#2) can be appropriately controlled, by performing communication with the cell C2 (TRP201#2), transmission of the uplink signal to the cell C2 (TRP201#2) can be appropriately controlled.

[0171] Also, the UE 100 (control unit 120) may hold the first TA value and the second TA value even when the first adjustment timer expires. Also, the UE 100 (control unit 120) may hold the second TA value even when the second adjustment timer expires. Thereby, when the UE 100 (control unit 120) communicates with the cell C2 (TRP201#2), it is not necessary to newly acquire the first TA value and / or the second TA value, so that the signaling between the UE 100 and the base station 200 can be reduced.

[0172] Also, when the second adjustment timer expires, the UE 100 (control unit 120) may release the second resource and hold the first resource. Thereby, the UE 100 (control unit 120) can continue to perform data communication with the cell C1 (TRP201#1) using the first resource even when communication with the cell C2 (TRP201#2) is not performed due to the release of the second resource.

[0173] (6) Sixth operation example With reference to FIGS. 17 and 18, the sixth operation example in the mobile communication system 1 will be mainly described in terms of differences from the above-described operation examples. In this operation example, the UE 100 (control unit 120) independently manages the first adjustment value and the second adjustment value. Therefore, the first adjustment value and the second adjustment value may be different.

[0174] As shown in FIG. 17, in step S401, UE100 (control unit 120) calculates the transmission timing difference (time difference) between the first transmission timing and the second transmission timing (see FIG. 18).

[0175] UE100 (control unit 120) determines the first adjustment value and the second adjustment value, respectively, in order to adjust the first transmission timing and the second transmission timing, for example, in the same manner as the above-described operation example. Next, UE100 (control unit 120) calculates the difference between the first adjustment value and the second adjustment value as the transmission timing difference (time difference).

[0176] In step S402, UE100 (control unit 120) determines whether or not the calculated time difference (transmission timing difference) exceeds the maximum allowable value.

[0177] The maximum allowable value is a value equal to or less than the range of the transmission window provided on the transmission circuit side of UE100 (control unit 120). The maximum allowable value may be the maximum transmission timing difference between the first transmission timing and the second transmission timing. The maximum allowable value may be defined in the 3GPP specification.

[0178] If the calculated time difference exceeds the maximum allowable value, UE100 (control unit 120) executes the process of step S403. On the other hand, if the calculated time difference does not exceed the maximum allowable value, UE100 (control unit 120) executes the process of step S405.

[0179] In step S403, UE100 (control unit 120) stops transmitting the second uplink signal to cell C2 (TRP201#2). UE100 (control unit 120) may stop transmitting the second uplink signal to cell C2 (TRP201#2), for example, in the MAC layer.

[0180] On the other hand, UE100 (control unit 120) does not stop transmitting the first uplink signal to cell C1 (TRP201#1). Therefore, UE100 (transmission unit 111) transmits the first uplink signal to cell C1 (TRP201#1) at the first transmission timing.

[0181] UE100 (control unit 120) may execute the process of step S404 in addition to the process of step S403.

[0182] Alternatively, until UE100 (control unit 120) receives the first TA or the second TA from base station 200, except for random access, UE100 may stop transmitting the second uplink signal to cell C2 (TRP201#2). UE100 (control unit 120) may calculate the first adjustment value or the second adjustment value based on the new first TA or second TA, and execute the process of step S401. UE100 may perform random access to cell C2 (TRP201#2) in response to the calculated time difference exceeding the maximum allowable value.

[0183] In step S404, UE100 (control unit 120) considers that the second adjustment timer has expired. If the difference between the first transmission timing and the second transmission timing exceeds the maximum allowable value, UE100 (control unit 120) may consider that the second adjustment timer has expired. When UE100 (control unit 120) considers that the second adjustment timer has expired, UE100 can execute an operation example similar to the above operation example. UE100 (control unit 120) may, for example, release the second resource. UE100 (control unit 120) may hold the second TA value calculated based on the second TA.

[0184] As a result, when UE100 (control unit 120) communicates with cell C2 (TRP201#2) after the second adjustment timer has expired, it is not necessary to newly acquire the second TA value, so the signaling between UE100 and base station 200 can be reduced.

[0185] In step S405, UE100 (control unit 120) executes simultaneous transmission. UE100 (control unit 120) controls UE100 (transmission unit 111) so that UE100 (transmission unit 111) transmits the first uplink signal to cell C1 (TRP201#1) at the first transmission timing and transmits the second uplink signal to cell C2 (TRP201#2) at the second transmission timing.

[0186] According to the above, when there is a possibility that the transmission of the uplink signal to cell C1 (TRP201#1) and the transmission of the second uplink signal to cell C2 (TRP201#2) do not fall within the range of the transmission window and the first uplink signal to cell C1 (TRP201#1) cannot be transmitted at the first transmission timing, by stopping the transmission of the second uplink signal to cell C2 (TRP201#2), the first uplink signal to cell C1 (TRP201#1) can be transmitted at the first transmission timing. In this way, by appropriately controlling the transmission timing of the second uplink signal for cell C2 (TRP201#2), the transmission of the uplink signal can be appropriately controlled. First

[0187] (Other Embodiments) The operation sequence (and operation flow) in the above-described embodiments does not necessarily have to be executed in time series in the order described in the flowchart or sequence diagram. For example, the steps in the operation may be executed in an order different from the order described as the flowchart or sequence diagram, or may be executed in parallel. Also, some of the steps in the operation may be deleted, and additional steps may be added to the process. Further, the operation sequence (and operation flow) in the above-described embodiments may be implemented separately and independently, or two or more operation sequences (and operation flows) may be combined and implemented. For example, some steps of one operation flow may be added to another operation flow, or some steps of one operation flow may be replaced with some steps of another operation flow.

[0188] ​In the above-described embodiments, the mobile communication system 1 has been described by taking a mobile communication system based on NR as an example. However, the mobile communication system 1 is not limited to this example. The mobile communication system 1 may be a system compliant with any TS of LTE or other generation systems (e.g., the sixth generation) of the 3GPP standard. The base station 200 may be an eNB that provides E-UTRA user plane and control plane protocol terminations to 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.

[0189] A program may be provided to cause 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. By using the computer-readable medium, it is possible to install the program in the 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. Also, circuits for executing 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 (chipset, SoC).

[0190] In the above embodiments, "transmit" may mean performing processing on at least one layer within the protocol stack used for transmission, or may mean physically transmitting a signal wirelessly or via wire. Alternatively, "transmit" may mean a combination of performing the processing on the at least one layer and physically transmitting a signal wirelessly or via wire. Similarly, "receive" may mean performing processing on at least one layer within the protocol stack used for reception, or may mean physically receiving a signal wirelessly or via wire. Alternatively, "receive" may mean a combination of performing the processing on the at least one layer and physically receiving a signal wirelessly or via wire. Similarly, "obtain / acquire" may mean obtaining information from stored information, obtaining information from information received from other nodes, or obtaining the information by generating the information. Similarly, "include" and "comprise" do not mean including only the listed items, and may mean including only the listed items or including additional items in addition to the listed items. Similarly, in the present disclosure, "or" does not mean an exclusive disjunction, but means a disjunction.

[0191] As described above, the embodiments have been described in detail with reference to the drawings. However, the specific configuration is not limited to the above, and various design changes and the like can be made without departing from the gist.

Description of Reference Numerals

[0192] 100: UE 110: Communication Unit 111: Transmission Unit 112: Reception Unit 120: Control Unit 200: Base Station 210: Communication Unit 211: Transmission Unit 212: Reception Unit 220: Network Interface 230: Control Unit 300: Core Network Device C1, C2: Cells

Claims

1. A communication device (100), receiving, by radio resource control (RRC) signaling, from a base station (200), as a setting to the communication device in one serving cell having a physical cell identifier, setting information including information for setting each of an identifier of a first timing advance group and an identifier of a second timing advance group, and receiving a random access response from the base station (200) in a random access procedure; a receiving unit (112); a control unit (120) configured to control a first time alignment timer corresponding to the first timing advance group based on reception of a timing advance command corresponding to the first timing advance group included in the random access response, and to control a second time alignment timer corresponding to the second timing advance group based on reception of a timing advance command corresponding to the second timing advance group included in the random access response; wherein the control unit controls a timing of the first uplink transmission based on a timing advance command corresponding to the first timing advance group and a first offset for adjusting a timing of the first uplink transmission corresponding to the serving cell; controls a timing of the second uplink transmission based on a timing advance command corresponding to the second timing advance group and a second offset for adjusting a timing of the second uplink transmission corresponding to a cell having a physical cell identifier different from the physical cell identifier of the serving cell; the receiving unit receives, from the base station (200), information for activating a transmission configuration indicator (TCI) state corresponding to the identifier of the second timing advance group; when the second time alignment timer expires, the control unit releases resources of a physical uplink shared channel for reporting semi-persistent channel state information corresponding to the activated TCI state, and retains an adjustment value of a timing for uplink transmission of the second timing advance group communication device.

2. When the second time alignment timer corresponding to the second timing advance group expires, the control unit holds an adjustment value for the timing of the uplink transmission in the second timing advance group. The communication device according to claim 1.

3. A base station (100), Using radio resource control (RRC) signaling, setting information including identifiers for each of a first timing advance group and a second timing advance group is transmitted to the communication device (100) as a setting for the communication device (100) in one serving cell having a physical cell identifier, and a transmission unit (211) that transmits a random access response to the communication device (100) in a random access procedure; A control unit (230) that controls a first time alignment timer corresponding to the first timing advance group based on transmission of a timing advance command corresponding to the first timing advance group included in the random access response, and controls a second time alignment timer corresponding to the second timing advance group based on transmission of a timing advance command corresponding to the second timing advance group included in the random access response, The timing of the first uplink transmission is controlled based on a timing advance command corresponding to the first timing advance group and a first offset for adjusting the timing of the first uplink transmission corresponding to the serving cell, and the timing of the second uplink transmission is controlled based on a timing advance command corresponding to the second timing advance group and a second offset for adjusting the timing of the second uplink transmission corresponding to a cell having a physical cell identifier different from the physical cell identifier of the serving cell, The transmission unit transmits information for activating a transmission configuration indicator (TCI) state corresponding to the identifier of the second timing advance group to the communication device (100), In the communication device (100), when the second time alignment timer expires, resources of a physical uplink shared channel for reporting semi-persistent channel state information corresponding to the activated TCI state are released, and an adjustment value of timing for uplink transmission of the second timing advance group is maintained. Base station.

4. When the second time alignment timer corresponding to the second timing advance group expires, the control unit maintains an adjustment value of timing for the uplink transmission in the second timing advance group. The base station according to claim 3.

5. A communication method executed by a communication device (100), comprising: receiving, from a base station (200), configuration information including information for configuring respective identifiers of a first timing advance group and a second timing advance group, as configuration to the communication device in one serving cell having a physical cell identifier, using radio resource control (RRC) signaling; receiving, from the base station (200), a random access response in a random access procedure; controlling a first time alignment timer corresponding to the first timing advance group based on reception of a timing advance command corresponding to the first timing advance group included in the random access response; controlling, by a control unit (120), a second time alignment timer corresponding to the second timing advance group based on reception of a timing advance command corresponding to the second timing advance group included in the random access response; controlling the timing of the first uplink transmission based on the timing advance command corresponding to the first timing advance group and a first offset for timing adjustment of the first uplink transmission corresponding to the serving cell; controlling the timing of the second uplink transmission based on the timing advance command corresponding to the second timing advance group and a second offset for timing adjustment of the second uplink transmission corresponding to a cell having a physical cell identifier different from the physical cell identifier of the serving cell. Receiving, from the base station, information for activating a transmission configuration indicator (TCI) state corresponding to an identifier of the second timing advance group; When the second time alignment timer expires, releasing resources of a physical uplink shared channel for reporting semi-persistent channel state information corresponding to the activated TCI state, and maintaining an adjustment value of timing for uplink transmission of the second timing advance group; A communication method.

6. When the second time alignment timer expires, comprising the step of maintaining an adjustment value of timing of the uplink transmission in the second timing advance group. The communication method according to claim 5.

Images