Communication device, base station, and communication method

Abstract

A communication device (100) comprises: a reception unit that receives a system information block (SIB) from a base station (200); and a control unit (120) that determines the number of bits in an availability indicator bitmap of a tracking reference signal (TRS) in downlink control information (DCI). If a TRS resource set configuration, which is a TRS resource set list, is included in the SIB, the control unit (120) determines the number of bits on the basis of an identifier corresponding to the TRS resource set. If the TRS resource set configuration is not included in the SIB, the control unit (120) determines the number of bits to be zero.

Description

Cross-reference to related applications

[0001] This application is based on and claims the benefit of priority of patent application No. 2022-001588 filed on January 7, 2022, and all the contents of the patent application are incorporated herein by reference.

Technical Field

[0002] The present disclosure relates to a communication device, a base station, and a communication method used in a mobile communication system.

Background Art

[0003] In a mobile communication system compliant with the technical specifications of 3GPP (registered trademark; the same shall apply hereinafter) (3rd Generation Partnership Project), which is a standardization project for mobile communication systems, for a communication device in the radio resource control (RRC) connected state, there is a tracking reference signal (TRS) in the reference signal (RS) individually set for the communication device. The TRS is a reference signal for performing time-frequency synchronization (time-frequency tracking).

[0004] In 3GPP, discussions are being held on the standardization of technologies for reducing power consumption for communication devices in the RRC idle state or the RRC inactive state. In such technologies, it has been considered to make the TRS resources (also referred to as "TRS opportunities") set for communication devices in the RRC connected state available also for communication devices in the RRC idle state or the RRC inactive state (see, for example, Non-Patent Document 1). Specifically, the base station broadcasts the TRS resource setting by means of a system information block (also referred to as "notification information").

[0005] A communication device in the RRC idle state or RRC inactive state can achieve synchronization by receiving the TRS using the TRS resource setting configured by the system information block, without receiving the SSB (SS / PBCH Block), and can shorten the wake-up duration from when synchronization is established until paging is monitored. And by not receiving the SSB, an increase in power consumption associated with the reception of the SSB is suppressed.

[0006] The base station transmits downlink control information (DCI) including an availability indicator indicating whether the TRS is transmitted based on the TRS resource set configured by the TRS resource setting to the communication device. The communication device determines whether the TRS is transmitted based on the configured TRS resource set based on the availability indicator (see, for example, Non-Patent Document 1). Note that the availability indicator field in which the availability indicator is stored is a variable-length field indicated by a maximum of 6 bits.

Prior Art Documents

Non-Patent Documents

[0007]

Non-Patent Document 1

Summary of the Invention

[0008] According to a first aspect Communication The apparatus includes a receiving unit that receives a system information block (SIB) from a base station, and a control unit that determines the number of bits of a bitmap of an availability indicator of a tracking reference signal (TRS) in downlink control information (DCI). When the TRS resource set configuration, which is a list of TRS resource sets, is included in the SIB, the control unit determines the number of bits based on an identifier associated with the TRS resource set, and when the TRS resource set configuration is not included in the SIB, the control unit determines the number of bits to be 0.

[0009] The base station according to the second aspect includes a transmission unit that transmits a system information block (SIB), and a control unit that determines the number of bits of a bitmap of an availability indicator of a tracking reference signal (TRS) in downlink control information (DCI). The control unit determines the number of bits based on an identifier associated with the TRS resource set when the TRS resource set configuration, which is a list of TRS resource sets, is included in the SIB, and determines the number of bits to be 0 when the TRS resource set configuration is not included in the SIB. is is included in the SIB rare In the case, based on the identifier associated with the TRS resource set and determines the number of bits, and when the TRS resource set configuration is not included in the SIB, determines the number of bits to be 0.

[0010] The communication method according to the third aspect is a communication method executed by a communication device. The communication method includes a step of receiving a system information block (SIB) from a base station, and a step of determining the number of bits of a bitmap of an availability indicator of a tracking reference signal (TRS) in downlink control information (DCI). In the determining step, when the TRS resource set configuration, which is a list of TRS resource sets, is included in the SIB, the number of bits is determined based on an identifier associated with the TRS resource set, and when the TRS resource set configuration is not included in the SIB, the number of bits is determined to be 0.

Brief Description of the Drawings

[0011] The objects, features, advantages, etc. of the present disclosure will become clearer from the following detailed description with reference to the accompanying drawings.

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DETAILED DESCRIPTION OF THE INVENTION

[0012] 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.

[0013] In the current 3GPP specification, a method for a communication device to determine the number of bits of the availability indicator field is not defined. As a result, there is a possibility that the communication device may misidentify the availability indicator field and cannot correctly determine whether to transmit the TRS based on the set TRS resource set. Therefore, one of the objectives of the present disclosure is to provide a communication device, a base station, and a communication method that can correctly determine whether to transmit the TRS based on the set TRS resource set.

[0014] (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, for example, a system compliant with the 3GPP Technical Specification (TS). Hereinafter, as the mobile communication system 1, a 5th Generation System (5GS) of the 3GPP standard, that is, a mobile communication system based on NR (New Radio) will be described as an example.

[0015] 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.

[0016] UE100 is an example of a communication device. UE100 may be a mobile wireless communication device. UE100 may be a device used by a user. UE100 may be a user equipment defined in the 3GPP technical specifications. UE100 is, for example, a mobile device such as a mobile phone terminal like 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 transportation 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.

[0017] 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 composed of one component carrier. The term "cell" may represent a wireless communication resource and may also represent a communication target of UE100. Each base station 200 can perform wireless communication with UE100 present in its cell. The base station 200 communicates with UE100 using the RAN protocol stack. 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).

[0018] 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 the UE100. 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] Referring to FIG. 2, a configuration example of a protocol stack in the mobile communication system 1 according to the embodiment will be described.

[0020] The protocol of the radio section between the UE100 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.

[0021] The PHY layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Between the PHY layer of the UE100 and the PHY layer of the base station 200, data and control information are transmitted via a physical channel.

[0022] 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 spacing can be included in a subframe.

[0023] Among 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.

[0024] 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. For the UE 100, for example, up to four BWPs can be set. Each BWP may have a different subcarrier spacing or the frequencies may overlap with each other. When multiple BWPs are set for the UE 100, the base station 200 can specify which BWP to activate by control in the downlink. Thereby, the base station 200 can dynamically adjust the UE bandwidth according to, for example, the amount of UE data traffic, and can reduce UE power consumption.

[0025] 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.

[0026] The MAC layer performs priority control of data, retransmission processing by Hybrid ARQ (HARQ), and random access procedures, etc. Between the MAC layer of UE100 and the MAC layer of base station 200, data and control information are transmitted via the transport channel. The MAC layer of base station 200 includes a scheduler. The scheduler determines the uplink and downlink transport formats (transport block size, modulation and coding scheme (MCS)) and the allocated resources for UE100.

[0027] 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 UE100 and the RLC layer of base station 200, data and control information are transmitted via the logical channel.

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

[0029] 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.

[0030] The RRC layer controls the logical channel, transport channel, and physical channel according to the establishment, re - establishment, and release of radio bearers. Between the RRC layer of UE100 and the RRC layer of base station 200, RRC signaling for various settings is transmitted. When there is an RRC connection between the RRC of UE100 and the RRC of base station 200, UE100 is in the RRC connected state. When there is no RRC connection between the RRC of UE100 and the RRC of base station 200, UE100 is in the RRC idle state. When the RRC connection between the RRC of UE100 and the RRC of base station 200 is suspended, UE100 is in the RRC inactive state.

[0031] The NAS layer located above the RRC layer performs session management and mobility management of UE100. Between the NAS layer of UE100 and the NAS layer of core network device 300 (AMF), NAS signaling is transmitted. Note that UE100 has an application layer etc. in addition to the protocol of the radio interface.

[0032] (Assumed scenario) With reference to FIGS. 3 to 6, the assumed scenarios in the mobile communication system 1 according to the embodiment will be described.

[0033] UE 100 in the RRC idle state or the RRC inactive state monitors paging from the base station 200. Specifically, UE 100 checks whether there is paging addressed to UE 100 by receiving the PDCCH (Physical Downlink Control Channel) from the base station 200. For example, UE 100 may receive (decode) the downlink control information (DCI) with a cyclic redundancy check (CRC) (CRC parity bits) scrambled by the P-RNTI (Paging Radio Network Temporary Identifier) in the PDCCH to receive the paging message. Here, the base station 200 may set the P-RNTI for UE 100. Also, the DCI may be a DCI format used for scheduling the PDSCH (Physical Downlink Shared Channel). That is, the paging message may be transmitted in the PDSCH. Here, the DCI with the CRC (CRC parity bits) scrambled by the P-RNTI is also referred to as paging DCI.

[0034] Here, UE 100 intermittently monitors paging using discontinuous reception (DRX: Discontinuous Reception) to reduce power consumption. The period for monitoring such paging is referred to as the DRX period. Also, the frame in which UE 100 should monitor paging is called the paging frame (PF), and the subframe in the PF in which UE 100 should monitor paging is called the paging occasion (PO: Paging Occasion).

[0035] Fig. 3 shows an operation example of an eDRX UE (i.e., an eDRX user device) that performs extended discontinuous reception (eDRX).

[0036] eDRX is a technology that uses a longer DRX cycle compared to normal DRX to achieve further power savings for UE100. The UE100 with DRX configured wakes up every DRX cycle to monitor the PDCCH, and when this monitoring ends, it enters the sleep state until the next DRX cycle. Therefore, by using a DRX cycle (hereinafter referred to as "eDRX cycle") that is longer than normal DRX, the period during which the receiver of UE100 can be turned off becomes longer, and further power savings are achieved.

[0037] In normal DRX, the DRX cycle is set to a time duration of, for example, 32 radio frames, 64 radio frames, 128 radio frames, or 256 radio frames. In contrast, the eDRX cycle used in eDRX is set to a time duration that is an integer multiple of a hyperframe consisting of 1024 radio frames.

[0038] On the other hand, the UE100 with eDRX configured (i.e., eDRX UE) attempts to receive paging in a specific hyperframe (PH: Paging Hyperframe) every eDRX cycle. At this time, the time width for monitoring paging is called PTW (Paging Timing Window), and during the PTW period, the PO (Paging Occasion) is monitored according to normal DRX.

[0039] FIG. 4 shows an operation example for a UE in the RRC idle state or RRC inactive state.

[0040] As shown in FIG. 4, in step S11, the base station 200 transmits the SSB to the UE 100. The SSB is another example of a downlink reference signal. 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, the SSB may be composed of four consecutive OFDM symbols in the time domain. Also, the SSB may be composed of 240 subcarriers (i.e., 20 resource blocks) consecutive in the frequency domain. The PBCH is a physical channel that carries the Master Information Block (MIB). The UE 100 performs time and frequency synchronization by receiving the SSB.

[0041] In step S12, the UE 100 monitors and receives paging at the PO. Note that the UE 100 maintains a wake-up state from the reception of the SSB in step S11 until the PO. Therefore, the longer the time from the reception timing of the SSB to the timing of the PO, the longer the wake-up duration, and the power consumption of the UE 100 increases.

[0042] In 3GPP, discussions are being held towards standardizing technologies for reducing power consumption for the UE 100 in the RRC idle state or the RRC inactive state. In such technologies, it is being considered to make the TRS resources (also referred to as "TRS opportunities") set for the UE 100 in the RRC connected state available also for the UE 100 in the RRC idle state or the RRC inactive state. Specifically, the base station 200 broadcasts a TRS resource setting, which is a setting for the TRS resources, by means of a System Information Block (also referred to as "notification information").

[0043] FIG. 5 shows an operation example for UE 100 in the RRC idle state or the RRC inactive state to receive a TRS. Note that the TRS may be a CSI-RS (Channel State Information - Reference Signal) used for tracking purposes. That is, in the present embodiment, the TRS resource may include a CSI-RS resource.

[0044] In step S21, the base station 200 transmits a specific system information block (hereinafter sometimes referred to as a specific SIB) including a TRS resource setting. Specifically, the base station 200 broadcasts a system information block including one or a plurality of TRS resource setting parameter groups on a broadcast channel. The specific system information block may be an existing system information block other than the system information block type 1 (SIB1), or may be a newly introduced type of system information block. UE 100 receives the specific system information block.

[0045] UE 100 sets a TRS resource set according to the TRS resource setting included in the specific system information block. Specifically, UE 100 sets a TRS resource set based on one or a plurality of TRS resource setting parameter groups.

[0046] Here, the TRS resource configuration for setting the TRS for the UE 100 in the RRC idle state or the RRC inactive state is CSI-ResourceConfig / NZP-CSI-RS-ResourceSet, and may include bwp-ID, resourceType, trs-Info, repetition, powerControlOffset, powerControlOffsetSS, frequencyDomainAllocation, firstOFDMSymbolInTimeDomain, Density, startingRB, nrofRBs, and subcarrierSpacing as each parameter (see 3GPP TS38.331). The TRS resource configuration may be only a part of the parameter group set for the UE 100 in the RRC connected state.

[0047] In step S22, the base station 200 transmits downlink control information (DCI) to the UE 100. The UE 100 receives the DCI from the base station 200.

[0048] The DCI includes an availability indicator indicating whether the TRS is transmitted based on the set TRS resource set. The availability indicator may be referred to as the TRS availability indicator.

[0049] The UE 100 determines whether the TRS is transmitted based on the set TRS resource set according to the availability indicator. If the UE 100 determines that the TRS is transmitted, it executes the process of step S23. If the UE 100 determines that the TRS is not transmitted, it does not have to execute the process of step S23. In this case, the UE 100 may execute the process of receiving the SSB.

[0050] In this way, the base station 200 can flexibly control the time-frequency synchronization based on the TRS by notifying the UE 100 via the DCI whether to transmit the TRS.

[0051] In step S23, the base station 200 transmits the TRS. The UE 100 receives the TRS using the TRS resource configuration. By receiving the TRS, the UE 100 can achieve time and frequency synchronization without receiving the SSB.

[0052] In step S24, the UE 100 monitors and receives paging at the PO. Note that the UE 100 maintains a wake-up state from the reception of the TRS in step S21 until the PO. When the time from the reception timing of the TRS to the timing of the PO is short, the wake-up duration becomes short, and the power consumption of the UE 100 is reduced. Also, by not receiving the SSB, the UE 100 can reduce the power consumption associated with the reception of the SSB.

[0053] Here, the availability indicator field including the availability indicator is a variable-length field indicated by up to 6 bits. However, in the current 3GPP specification, the method for the UE 100 to determine the number of bits of the availability indicator field is not defined. As a result, there is a possibility that the UE 100 may misidentify the availability indicator field and cannot correctly determine whether the TRS is transmitted based on the set TRS resource set. In an embodiment described later, an operation for correctly determining whether the TRS is transmitted based on the set TRS resource set will be described.

[0054] Also, when a specific SIB includes a TRS resource set for a general UE performing DRX and a TRS resource set for an eDRX UE performing eDRX, it is unclear how the UE 100 determines the number of bits of the availability indicator field. As a result, there is a possibility that the UE 100 may misidentify the availability indicator field and cannot correctly determine whether the TRS is transmitted based on the set TRS resource set. In an embodiment described later, an operation for correctly determining whether the TRS is transmitted based on the set TRS resource set will be described.

[0055] (Configuration of User Equipment) Referring to FIG. 6, the configuration of the UE 100 according to the embodiment will be described. The UE 100 includes a communication unit 110 and a control unit 120.

[0056] The communication unit 110 performs wireless communication with the base station 200 by transmitting and receiving wireless 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 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.

[0057] 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 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 the 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. 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.

[0058] The UE 100 configured as described above performs time and frequency synchronization in the downlink using the TRS. In the UE 100, the receiving unit 112 receives from the base station 200 a specific SIB including the TRS resource setting and a DCI including an availability indicator indicating whether the TRS is transmitted based on the TRS resource set configured by the TRS resource setting. The control unit 120 determines, based on the availability indicator, whether the TRS is transmitted based on the configured TRS resource set. The control unit 120 determines the number of bits of the availability indicator field in which the availability indicator is stored based on the number of TRS resource set groups defined by the TRS resource setting. Thereby, the UE 100 can identify the availability indicator field and correctly determine whether the TRS is transmitted based on the configured TRS resource set.

[0059] (Configuration of the 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 communication unit 210, a network communication unit 220, and a control unit 230.

[0060] 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 transmitting unit 211 and at least one receiving unit 212. The transmitting unit 211 and the receiving 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.

[0061] The network communication unit 220 transmits and receives signals to and from the network. The network communication unit 220 receives, for example, a signal from an adjacent base station connected via an Xn interface which is a base station-to-base station interface, and transmits a signal to the adjacent base station. Also, the network communication unit 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.

[0062] The control unit 230 performs various controls in the base station 200. For example, the control unit 230 controls communication with the UE 100 via the communication unit 210. Also, for example, the control unit 230 controls communication with nodes (e.g., neighboring base stations, core network devices 300) via the network communication unit 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 for storing the program. The processor may execute the program to perform the operations of the control unit 230. The control unit 230 may also 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.

[0063] The base station 200 configured as described above performs wireless communication with the UE 100 that performs time and frequency synchronization in the downlink using the TRS. In the base station 200, the transmission unit 211 transmits to the UE 100 an SIB including a TRS resource setting and a DCI including an availability indicator indicating whether the TRS is transmitted based on the TRS resource set set by the TRS resource setting. The control unit 230 determines the number of bits of the availability indicator field in which the availability indicator is stored based on the number of TRS resource set groups defined by the TRS resource setting. Thereby, the UE 100 can identify the availability indicator field and correctly determine whether the TRS is transmitted based on the set TRS resource set.

[0064] (First operation example) With reference to FIGS. 8 to 11, the first operation example will be described. This operation is premised on the above-described configuration and operation. Therefore, the description given above may be omitted.

[0065] In step S101, the transmission unit 211 of the base station 200 transmits a specific SIB including TRS resource configuration. The reception unit 112 of the UE 100 receives the specific SIB. Hereinafter, the specific SIB may include the configuration of a tracking TRS (for example, CSI-RS) that can be used by the UE 100 in the RRC idle state or the RRC inactive state. The specific SIB may be referred to as SIBXX.

[0066] The specific SIB includes the TRS resource configuration. As shown in FIG. 9, the specific SIB may include, as the TRS resource configuration, a TRS resource set configuration (trs-ResourceSetConfig-r17 / TRS-ResourceSetConfig-r17), an individual TRS configuration list (nzp-CSI-RS-ResourceListForTracking-r17), and a common TRS configuration (nzp-CSI-RS-ResourceCommon-r17 / NZP-CSI-RS-ResourceCommon-r17) (see E91 in FIG. 9). Note that “-r17” means an information element introduced in Release 17 of the 3GPP technical specification, but these information elements may be introduced after Release 18.

[0067] The TRS resource set configuration (TRS-ResourceSetConfig-r17) may be constituted by one or a plurality of TRS resource set groups (TRS-ResourceSetGroup-r17) (see E92 in FIG. 9). Specifically, the TRS resource set configuration may be constituted in a list format including the TRS resource set group. In this way, the TRS resource set configuration may define the TRS resource set group.

[0068] The TRS resource set group may be a list of TRS resource sets (NZP-CSI-RS-ResourceSetSIB-r17) (see E93 in Figure 9). Therefore, the TRS resource set group is composed of grouped TRS resource sets. That is, the TRS resource set configuration may be a parameter for grouping TRS resource sets.

[0069] The TRS resource set may be a set of a TRS resource set identifier (nzp-CSI-ResourceSetId-r17 / NZP-CSI-RS-ResourceSetId) and TRS resources (nzp-CSI-RS-Resources-r17). Note that the TRS resources may be a list of identifiers (NZP-CSI-RS-ResourceId) of the TRS resources associated with the TRS resources.

[0070] The individual TRS configuration list is a list of individual TRS configurations (NZP-CSI-RS-ResourceSIB-r17). As shown in Figure 10, the individual TRS configuration may include an identifier (nzp-CSI-RS-ResourceId / NZP-CSI-RS-ResourceId) of the TRS resource, a parameter (frequencyDomainAllocation) indicating the allocation in the frequency direction of the TRS, a parameter (firstOFDMSymbolInTimeDomain) indicating the allocation in the time direction of the TRS, and a parameter (scramblingID / ScramblingId) indicating the scrambling identifier of the TRS.

[0071] The common TRS configuration may be a set of parameters that are commonly applied to all individual TRS configurations. As shown in FIG. 10, the common TRS configuration may include a parameter (csi-FrequencyOccupation-r17 / CSI-FrequencyOccupation) indicating the occupied range of the TRS in the frequency direction, a parameter (powerControlOffsetSS-r17) indicating the power offset of the TRS with respect to the synchronization signal, a parameter (periodicityAndOffset-r17 / CSI-ResourcePeriodicityAndOffsetSIB-r17) indicating the periodicity and time offset of the TRS, and a parameter (qcl-InfoForTracking-r17) regarding the QCL of the TRS.

[0072] In step S102, the control unit 120 of the UE 100 determines the number of bits of the availability indicator field. Specifically, the control unit 120 of the UE 100 determines the number of bits of the availability indicator field based on the number of TRS resource set groups. When the TRS resource set configuration is in a list form including TRS resource set groups, the control unit 120 of the UE 100 determines the number of bits of the availability indicator field based on the number of entries of one or more TRS resource set groups in the list form. When the number of entries (which may be the entry size) of the TRS resource set group is N, the control unit 120 of the UE 100 determines that the number of bits of the availability indicator field is N.

[0073] In step S103, the transmission unit 211 of the base station 200 transmits the DCI to the UE 100. The reception unit 112 of the UE 100 receives the DCI from the base station 200.

[0074] The DCI may be DCI format 1_0 used for PDSCH scheduling in one downlink cell. As shown in FIG. 11, DCI format 1_0 may include a TRS availability indication (see E111 in FIG. 11). The availability indicator may be stored in the availability indicator field within DCI format 1_0. The availability indicator may be transmitted by DCI format 1_0 scrambled by a paging - radio network temporary identifier (P-RNTI).

[0075] When the TRS-ResourceSetConfig is configured, the availability indicator is a bitmap with a bit number of any one from 1 to 6. Therefore, the availability indicator field is indicated by a bit number of any one from 1 to 6. On the other hand, when the TRS-ResourceSetConfig is not configured, the availability indicator (i.e., the availability indicator field) is 0 bits.

[0076] The bit positions of the bitmap constituting the availability indicator are associated with the entries of the TRS resource set group configured by the TRS-ResourceSetConfig. Specifically, the first bit or the leftmost bit corresponds to the first entry of the TRS resource set group configured by the TRS-ResourceSetConfig, and the second bit corresponds to the second entry of the TRS resource set group configured by the TRS-ResourceSetConfig. The number of bits in the availability indicator field corresponds to the number of TRS resource set groups configured by the TRS-ResourceSetConfig.

[0077] Alternatively, the DCI may be DCI format 2_7 used to notify one or more UEs 100 of paging early indicators and availability indicators. As shown in FIG. 11, the DCI format 2_7 may include an availability indicator (see E112 in FIG. 11). The availability indicator may be stored in an availability indicator field within the DCI format 2_7. The availability indicator may be transmitted by the DCI format 2_7 scrambled by a paging early indicator - radio network temporary identifier (PEI-RNTI).

[0078] In step S104, the control unit 120 of the UE 100 determines whether a TRS is transmitted.

[0079] The control unit 120 of the UE 100 identifies the availability indicator (or the availability indicator field) based on the determined number of bits of the availability indicator. The control unit 120 determines whether a TRS is transmitted based on the identified availability indicator.

[0080] Specifically, when the value at the bit position of the bitmap constituting the availability indicator is a predetermined value (e.g., "1"), the control unit 120 of the UE 100 determines that the TRS of the corresponding entry's TRS resource set group is being transmitted. On the other hand, when the value at the bit position is a value different from the predetermined value (e.g., "0"), the control unit 120 determines that the TRS of the corresponding entry's TRS resource set group is not being transmitted.

[0081] The control unit 120 determines whether a TRS is transmitted based on the TRS resource set, based on the value at the bit position corresponding to the entry of the TRS resource set group to which the TRS resource set set for the UE 100 belongs. When the control unit 120 determines that a TRS is transmitted based on the set TRS resource set, the process of step S105 is executed. If the UE 100 determines that a TRS is not transmitted, the process of step S105 does not have to be executed. In this case, the UE 100 may execute the process of receiving an SSB.

[0082] Steps S105 and S106 correspond to steps S23 and S24.

[0083] As described above, the transmission unit 211 of the base station 200 transmits to the UE 100 an SIB including a TRS resource setting and a DCI including an availability indicator indicating whether a TRS is transmitted based on a TRS resource set set by the TRS resource setting. The control unit 230 of the base station 200 determines the number of bits of the availability indicator field in which the availability indicator is stored based on the number of TRS resource set groups defined by the TRS resource setting. The reception unit 112 of the UE 100 receives from the base station 200 an SIB including a TRS resource setting and a DCI including an availability indicator indicating whether a TRS is transmitted based on a TRS resource set set by the TRS resource setting. The control unit 120 determines whether a TRS is transmitted based on the set TRS resource set based on the availability indicator. The control unit 120 determines the number of bits of the availability indicator field in which the availability indicator is stored based on the number of TRS resource set groups defined by the TRS resource setting. Thereby, the UE 100 can identify the availability indicator field and correctly determine whether a TRS is transmitted based on the set TRS resource set.

[0084] Also, the TRS resource setting may include a TRS resource set setting composed of one or more TRS resource set groups. The control unit 120 may determine the number of bits of the availability indicator field based on the number of TRS resource set groups constituting the TRS resource set setting. The control unit 120 can determine the number of bits of the availability indicator field according to the TRS resource set setting and correctly determine whether a TRS is transmitted based on the set TRS resource set.

[0085] Also, the TRS resource set configuration may be configured in a list format including one or more TRS resource set groups. The control unit 120 may determine the number of bits of the availability indicator field based on the number of entries of the one or more TRS resource set groups in the list format. Thereby, even if the TRS resource set configuration does not include an identifier for identifying a group, the control unit 120 can determine the number of bits of the availability indicator field and can reduce the amount of information of the TRS resource configuration.

[0086] Also, the bit positions of the bitmap constituting the availability indicator may be associated with the entries. When the value at the bit position is a predetermined value, the control unit 120 may determine that the TRS of the TRS resource set group of the corresponding entry is being transmitted. Thereby, the control unit 120 can determine whether the TRS is being transmitted based on the TRS resource set included in the TRS resource set group of the corresponding entry. As a result, it is possible to suppress the UE 100 from attempting to receive the TRS even though the TRS is not being transmitted.

[0087] (Second operation example) With reference to FIGS. 8, 12, and 13, a second operation example will be described. Descriptions similar to those in the above operation example will be omitted as appropriate. In the second operation example, the UE 100 determines the number of bits of the availability indicator field based on the group identifier.

[0088] In step S101, the transmission unit 211 of the base station 200 transmits the following specific SIB. The reception unit 112 of the UE 100 receives the specific SIB.

[0089] As shown in FIG. 12, the TRS resource set configuration (trs-ResourceSetConfig-r17) included in a specific SIB may be a list of TRS resource sets (NZP-CSI-RS-ResourceSetSIB-r17) (see E121 in FIG. 12). A TRS resource set may include a TRS resource set identifier (nzp-CSI-ResourceSetId-r17 / NZP-CSI-RS-ResourceSetId), TRS resources (nzp-CSI-RS-Resources-r17), and a group identifier (trs-ResourceSetGroupId-r17) that identifies a TRS resource set group (see E122 in FIG. 12). Therefore, one or more TRS resource sets are associated with a group identifier. The group identifier is an identifier (ID) of the TRS resource set group to which the associated TRS resource set belongs. Therefore, each TRS resource set group is configured by TRS resource sets with the same value of the corresponding group identifier. Note that the base station 200 (network 10) configures TRS resource set groups with consecutive IDs starting from 0.

[0090] In step S102, the control unit 120 of the UE 100 determines the number of bits of the availability indicator field based on the number of group identifiers. When the number of group identifiers is N, the control unit 120 determines the number of bits of the availability indicator field to be N.

[0091] In the DCI transmitted in step S103, each code point of the "availability indicator" in the DCI field, that is, the bit position of the bitmap of the availability indicator, is associated with the TRS resource set group ID. Specifically, the first bit or the leftmost bit of the bitmap constituting the availability indicator corresponds to the TRS resource set group ID0, and the second bit corresponds to the TRS resource set group ID1 (see E131 and E132 in FIG. 13).

[0092] In step S104, the control unit 120 of the UE 100 determines whether a TRS is being transmitted based on the set TRS resource set, based on the value at the bit position corresponding to the group identifier that identifies the TRS resource set group to which the set TRS resource set of the UE 100 belongs.

[0093] As described above, the TRS resource setting may include a TRS resource set setting composed of one or more TRS resource sets associated with a group identifier. The control unit 120 may determine the number of bits in the availability indicator field based on the number of group identifiers. Thereby, the UE 100 can identify the availability indicator field and correctly determine whether a TRS is being transmitted based on the set TRS resource set.

[0094] (Third operation example) Referring to FIGS. 8 and 14, the third operation example will be described. Descriptions similar to those of the above operation examples will be omitted as appropriate. In the third operation example, one or more TRS resource set groups and group identifiers are associated in a different format from the second operation example.

[0095] As shown in FIG. 14, a specific SIB includes a TRS resource setting, similar to the first operation example. In the TRS resource set setting (trs-ResourceSetConfig-r17 / TRS-ResourceSetConfig-r17) included in the TRS resource setting, one or more TRS resource set groups (TRS-ResourceSetGroup-r17) and a group identifier (trs-ResourceSetGroupId-r17) are associated (E141 in FIG. 14). Therefore, the TRS resource setting includes a TRS resource set setting in which one or more TRS resource set groups and a group identifier are associated.

[0096] In step S102, similar to the second operation example, the control unit 120 of the UE 100 determines the number of bits of the availability indicator field based on the number of group identifiers. Thereby, the UE 100 can identify the availability indicator field and correctly determine whether the TRS is transmitted based on the set TRS resource set.

[0097] (Fourth operation example) Referring to FIGS. 15 and 16, the fourth operation example will be described. Descriptions similar to the above operation examples will be omitted as appropriate. In the fourth operation example, the TRS resource setting includes separate TRS resource set groups for general UEs performing DRX and eDRX UEs.

[0098] As shown in FIG. 15, in step S201, the transmission unit 211 of the base station 200 transmits the following specific SIB. The reception unit 112 of the UE 100 receives the specific SIB.

[0099] The specific SIB includes a first TRS resource set group for general UEs performing DRX and a second TRS resource set group for eDRX UEs performing eDRX. In this operation example, different group identifiers are assigned to the first TRS resource set group and the second TRS resource set group.

[0100] Specifically, in FIG. 16, the first TRS resource set group includes a TRS resource set group constituted by a TRS resource set associated with group identifier #0 and a TRS resource set group constituted by a TRS resource set associated with group identifier #1. The second TRS resource set includes a TRS resource set group constituted by a TRS resource set associated with group identifier #2.

[0101] Each TRS resource set associated with each of group identifier #0 and group identifier #1 is a TRS resource set for normal UEs. Each TRS resource set associated with group identifier #2 is a TRS resource set for eDRX UEs.

[0102] Note that the specific SIB may include a group identifier and information indicating whether the TRS resource set associated with the group identifier is for eDRX UEs (or for normal UEs). Alternatively, each TRS resource set may be associated with information indicating whether the TRS resource set is for eDRX UEs (or for normal UEs). Alternatively, the group identifier may be associated with information indicating whether the TRS resource set associated with the group identifier is for eDRX UEs (or for normal UEs). The control unit 120 of the UE 100 can determine whether each TRS resource set is for normal UEs or for eDRX UEs based on the information.

[0103] The specific SIB may include period information indicating the validity duration of the availability indicator indicated by the availability indicator field for each of the first TRS resource set and the second TRS resource set. The period information may include first period information which is the validity duration of the availability indicator for the first TRS resource set and second period information which is the validity duration of the availability indicator for the second TRS resource set. The control unit 120 can determine the validity duration of the availability indicator for the first TRS resource set based on the first period information. Similarly, the control unit 120 can determine the validity duration of the availability indicator for the second TRS resource set based on the second period information.

[0104] The validity duration for the first TRS resource set may be an integer multiple of a first time unit. The first time unit may be, for example, one default paging cycle.

[0105] The validity period for the second TRS resource set may be an integer multiple of a second time unit that is longer than the first time unit. The first time unit may be, for example, an eDRX cycle, or may be an acquisition period (specifically, an eDRX acquisition period) that triggers the UE 100 with eDRX set to acquire an updated SIB.

[0106] In step S202, the control unit 120 of the UE 100 determines the number of bits of the availability indicator field. The control unit 120 determines the number of bits of the availability indicator field based on the total number of the first TRS resource set group and the second TRS resource set group.

[0107] For example, the control unit 120 may determine the number of bits of the availability indicator field based on the total number of group identifiers of the first TRS resource set group and the second TRS resource set group. In the example of FIG. 16, the control unit 120 may determine 3, which is the total number (i.e., the sum value) of 2, which is the number of group identifiers of the first TRS resource set group, and 1, which is the number of group identifiers of the second TRS resource set group, as the number of bits of the availability indicator field.

[0108] Steps S203 to S206 are the same as steps S103 to S106.

[0109] Note that, for example, when the first TRS resource set associated with the group identifier #0 is set, the control unit 120 determines whether the TRS is being transmitted based on the value of the first bit position of the bitmap constituting the availability indicator. Similarly, for example, when the second TRS resource set associated with the group identifier #2 is set, the control unit 120 determines whether the TRS is being transmitted based on the value of the third bit position of the bitmap constituting the availability indicator.

[0110] Note that when the UE 100 is a normal UE, the control unit 120 receives the TRS based on the first TRS resource set. When the UE 100 is an eDRX UE, the control unit 120 receives the TRS based on the second TRS resource set. For example, when a DRX setting is configured (e.g., a DRX cycle is applied), the control unit 120 determines that the UE 100 is a normal UE. On the other hand, for example, when an eDRX setting is configured (e.g., an eDRX cycle is applied), the control unit 120 determines that the UE 100 is an eDRX UE.

[0111] As described above, the control unit 120 may determine the number of bits of the availability indicator field based on the total number of the first TRS resource set group and the second TRS resource set group. Also, the control unit 120 may determine the number of bits of the availability indicator field based on the total number of the group identifiers of the first TRS resource set group and the second TRS resource set group. Thereby, even when a specific SIB includes a TRS resource set for a general UE performing DRX and a TRS resource set for an eDRX UE performing eDRX, the UE 100 can identify the availability indicator field and correctly determine whether the TRS is transmitted based on the configured TRS resource set.

[0112] Also, since different group identifiers are assigned to the first TRS resource set group and the second TRS resource set group, the base station 200 (network 10) can determine whether to transmit each of the TRS transmitted based on the first TRS resource set and the TRS transmitted based on the second TRS resource set. Thereby, the base station 200 can flexibly control the transmission of the TRS.

[0113] In addition, the receiving unit 112 receives, from the base station 200, a specific SIB including period information indicating the validity period of the availability indicator for each of the first TRS resource set and the second TRS resource set. Thereby, even when the first TRS resource set and the second TRS resource set are included in the specific SIB, the control unit 120 can grasp the validity period of the availability indicator for each of the first TRS resource set and the second TRS resource set. As a result, the UE 100 can correctly determine whether or not the TRS is transmitted based on the set TRS resource set.

[0114] (Fifth operation example) Referring to FIG. 17, the fifth operation example will be described. Similar descriptions to the above operation examples will be omitted as appropriate. In the fifth operation example, the UE 100 determines the number of bits of the availability indicator field based on the total number of the group with the larger number between the first TRS resource set group and the second TRS resource set group.

[0115] As shown in FIG. 17, in this operation example, group identifiers are individually assigned to the first TRS resource set group and the second TRS resource set group.

[0116] Specifically, in FIG. 17, the first TRS resource set group includes a TRS resource set group configured by a TRS resource set associated with group identifier #0 and a TRS resource set group configured by a TRS resource set associated with group identifier #1. The second TRS resource set includes a TRS resource set group configured by a TRS resource set associated with group identifier #0.

[0117] Each TRS resource set associated with each of group identifier #0 and group identifier #1 is a TRS resource set for a normal UE. Each TRS resource set associated with group identifier #0 is a TRS resource set for an eDRX UE.

[0118] The control unit 120 of the UE 100 may determine the number of bits of the availability indicator field based on the total number of the group with a larger number between the first TRS resource set group and the second TRS resource set group. The control unit 120 may determine the number of bits of the availability indicator field based on the total number of the group identifiers of the group with a larger number.

[0119] In the example of FIG. 16, the control unit 120 compares the number 2 of the group identifiers of the first TRS resource set group with the number 1 of the group identifiers of the second TRS resource set group, and determines that the number of the group identifiers of the first TRS resource set group is larger. The control unit 120 may determine the number 2 of the group identifiers of the first TRS resource set group with a larger number as the number of bits of the availability indicator field.

[0120] As described above, the control unit 120 may determine the number of bits of the availability indicator field based on the total number of the group with a larger number between the first TRS resource set group and the second TRS resource set group. Also, the control unit 120 may determine the number of bits of the availability indicator field based on the total number of the group identifiers with a larger number. Thereby, even when a specific SIB includes a TRS resource set for a general UE performing DRX and a TRS resource set for an eDRX UE performing eDRX, the UE 100 can identify the availability indicator field and correctly determine whether the TRS is transmitted based on the set TRS resource set.

[0121] Also, since the group identifiers are individually assigned to the first TRS resource set group and the second TRS resource set group, the base station 200 (network 10) can increase the number of the TRS resource set groups to which the group identifiers are assigned as compared with the fourth operation example. Thereby, the base station 200 can set the TRS resource setting in detail.

[0122] Note that in this operation example, when the control unit 230 of the base station 200 assigns the same group identifier (for example, group identifier #0 in FIG. 16) to the first TRS resource set group and the second TRS resource set group, for the TRS transmitted based on the first TRS resource set and the second TRS resource set to which the same group identifier is assigned, the control unit 230 of the base station 200 determines whether to transmit both TRSs or not to transmit both TRSs. That is, the control unit 230 of the base station 200 does not perform control to transmit the TRS based on one TRS resource set and not to transmit the TRS based on the other TRS resource set.

[0123] (Sixth operation example) Referring to FIG. 18, the sixth operation example will be described. Descriptions similar to those of the above operation examples will be omitted as appropriate. In the sixth operation example, the operation in which the UE 100 determines the validity period of the availability indicator for the second TRS resource set group will be described.

[0124] The control unit 120 of the UE 100 may execute the following processing based on, for example, the reception of a specific SIB.

[0125] As shown in FIG. 18, in step S301, the control unit 120 of the UE 100 determines whether the UE 100 is an eDRX UE. If the control unit 120 determines that the UE 100 is an eDRX UE, it executes the processing of step S302. On the other hand, if the control unit 120 determines that the UE 100 is not an eDRX UE, the processing may end.

[0126] Note that the control unit 120 may determine that the UE 100 is an eDRX UE when, for example, an eDRX setting is set (for example, an eDRX cycle is applied). The control unit 120 may determine that the UE 100 is not an eDRX UE when a DRX setting is set (for example, a DRX cycle is applied).

[0127] In step S302, the control unit 120 determines whether the specific SIB includes second period information indicating the validity period of the availability indicator for the second TRS resource set. If the control unit 120 determines that the specific SIB includes the second period information, it executes the process of step S303. If the control unit 120 determines that the specific SIB does not include the second period information, it executes the process of step S304.

[0128] In step S303, the control unit 120 determines the validity period based on the second period information.

[0129] In step S304, the control unit 120 may determine the validity period based on the eDRX cycle or the eDRX acquisition period, which is the acquisition cycle that triggers the acquisition of the updated SIB by the eDRX UE.

[0130] For example, the control unit 120 may regard the period until the next eDRX cycle as the validity period as a default setting. Alternatively, for example, the control unit 120 may regard the period until the boundary of the acquisition cycle as the validity period as a default setting.

[0131] As described above, when the UE 100 is an eDRX UE, if the specific SIB includes the second period information, which is the period information for the eDRX UE, the control unit 120 may determine the validity period based on the second period information. If the specific SIB does not include the second period information, the control unit 120 may determine the validity period based on the eDRX cycle or the eDRX acquisition period. Thereby, the UE 100 can appropriately determine the validity period regardless of the presence or absence of the second period information in the specific SIB. As a result, the control unit 120 can correctly determine whether the TRS is transmitted based on the set TRS resource set.

[0132] (Other embodiments) The operation sequences (and operation flows) in the above-described embodiments do not necessarily have to be executed in time series in accordance with the order described in the flowcharts or sequence diagrams. For example, the steps in the operations may be executed in an order different from the order described as a flowchart or sequence diagram, or may be executed in parallel. Also, some of the steps in the operations may be deleted, and additional steps may be added to the processing. Further, the operation sequences (and operation flows) in the above-described embodiments may be implemented separately and independently, or may be implemented by combining two or more operation sequences (and operation flows). 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.

[0133] In the above-described embodiment, a mobile communication system 1 based on NR has been described 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 one of LTE (Long Term Evolution) or other generation systems of the 3GPP standard (for example, the sixth generation). The base station 200 may be an eNB that provides E-UTRA user plane and control plane protocol termination 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.

[0134] 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. By using a computer-readable medium, it is possible to install the program in 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 (Compact Disk Read Only Memory) or a DVD-ROM (Digital Versatile Disc Read Only Memory). Further, 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 (chipset, SoC (System On Chip)).

[0135] 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, unless otherwise specified, the descriptions "based on" and "depending on / in response to" do not mean "only based on" and "only in response to". The description "based on" means both "only based on" and "at least partially based on". Similarly, the description "depending on" means both "only depending on" and "at least partially depending on". Similarly, "include" and "comprise" do not mean including only the recited items, and may mean including only the recited items or including additional items in addition to the recited items. Similarly, in the present disclosure, "or" means logical disjunction, not exclusive logical disjunction. Further, any reference to elements using designations such as "first", "second", etc. used in the present disclosure does not generally limit the quantity or order of those elements. These designations may be used in the present disclosure as a convenient way to distinguish between two or more elements.Accordingly, references to the first and second elements do not mean that only two elements may be employed there, or that the first element must precede the second element in some form. In the present disclosure, for example, when articles are added by translation, such as a, an, and the in English, these articles shall be construed to include pluralities unless the context clearly indicates otherwise.

[0136] The present disclosure has been described with reference to embodiments, but it is understood that the present disclosure is not limited to such embodiments and structures. The present disclosure also encompasses various modifications and variations within the equivalent scope. In addition, various combinations and forms, as well as other combinations and forms including only one element, more than one element, or less than one element thereof, fall within the scope and spirit of the present disclosure.

[0137] (Appendix) The features regarding the above-described embodiments are appended.

[0138] (Appendix 1) a receiving unit that receives a system information block (SIB) from a base station; a control unit that determines the number of bits of a bitmap of an availability indicator of a tracking reference signal (TRS) in downlink control information (DCI); The control unit: when a TRS resource set configuration, which is a list of TRS resource sets, is included in the SIB, determines the number of bits based on an identifier associated with the TRS resource set; when the TRS resource set configuration is not included in the SIB, determines the number of bits to be 0 A communication device.

[0139] (Appendix 2) The identifier is included in the TRS resource set configuration The communication device according to Appendix 1.

[0140] (Appendix 3) The DCI is accompanied by a Cyclic Redundancy Check (CRC) scrambled by a Paging Radio Network Temporary Identifier (P-RNTI). The communication device according to Appendix 1 or 2.

[0141] (Appendix 4) The DCI is accompanied by a Cyclic Redundancy Check (CRC) scrambled by a Paging Early Indicator - Radio Network Temporary Identifier (PEI-RNTI). The communication device according to any one of Appendices 1 to 3.

[0142] (Appendix 5) The receiving unit receives the DCI from the base station, Based on the determined number of bits, the control unit identifies the availability indicator of the received DCI The communication device according to any one of Appendices 1 to 4.

[0143] (Appendix 6) Based on the values of the bits of the bitmap of the determined number of bits, the receiving unit receives a Tracking Reference Signal (TRS) based on the TRS resource set The communication device according to any one of Appendices 1 to 5.

[0144] (Appendix 7) A transmitting unit that transmits a System Information Block (SIB), A control unit that determines the number of bits of a bitmap of an availability indicator of a Tracking Reference Signal (TRS) in Downlink Control Information (DCI), comprising: The control unit, A TRS resource set configuration that is a list of TRS resource sets is Is included in the SIB rare In this case, based on the identifier associated with the TRS resource set and Determine the number of bits, If the TRS resource set configuration is not included in the SIB, determine the number of bits to be 0 Base station.

[0145] (Appendix 8) A communication method executed by a communication device, comprising the steps of receiving a system information block (SIB) from a base station, and determining the number of bits of a bitmap of availability indicators of tracking reference signals (TRSs) in downlink control information (DCI), wherein in the step of determining, if a TRS resource set configuration, which is a list of TRS resource sets, is included in the SIB, the number of bits is determined based on an identifier associated with the TRS resource set, and if the TRS resource set configuration is not included in the SIB, the number of bits is determined to be 0. Communication method.

Claims

1. A receiving unit (112) that receives a system information block (SIB) from a base station (200), and A control unit (120) that determines the number of bits of a bitmap of an availability indicator of a tracking reference signal (TRS) in downlink control information (DCI), The control unit When a TRS resource set configuration, which is a list of TRS resource sets, is included in the SIB, determines the number of bits based on an identifier associated with the TRS resource set, When the TRS resource set configuration is not included in the SIB, determines the number of bits to be 0 A communication device (100).

2. The identifier is included in the TRS resource set configuration The communication device according to claim 1.

3. The DCI is accompanied by a cyclic redundancy check (CRC) scrambled by a paging radio network temporary identifier (P-RNTI) The communication device according to claim 1 or 2.

4. The DCI is accompanied by a cyclic redundancy check (CRC) scrambled by a paging early indicator - radio network temporary identifier (PEI-RNTI) The communication device according to claim 1 or 2.

5. The receiving unit receives the DCI from the base station, The control unit identifies the availability indicator of the received DCI based on the determined number of bits The communication device according to claim 1 or 2.

6. The receiving unit receives a TRS based on the TRS resource set based on the value of a bit of the bitmap of the determined number of bits The communication device according to claim 1 or 2.

7. A transmitting unit (211) that transmits a system information block (SIB), and A control unit (230) that determines the number of bits of a bitmap of an availability indicator of a tracking reference signal (TRS) in downlink control information (DCI), The control unit When a TRS resource set configuration, which is a list of TRS resource sets, is included in the SIB, determines the number of bits based on an identifier associated with the TRS resource set, When the TRS resource set configuration is not included in the SIB, determines the number of bits to be 0 A base station (200).

8. The identifier is included in the TRS resource set configuration The base station according to claim 7. **Claim 9**: The DCI is accompanied by a Cyclic Redundancy Check (CRC) scrambled by a Paging Radio Network Temporary Identifier (P-RNTI). The base station according to claim 7 or 8. **Claim 10**: The DCI is accompanied by a Cyclic Redundancy Check (CRC) scrambled by a Paging Early Indicator - Radio Network Temporary Identifier (PEI-RNTI). The base station according to claim 7 or 8. **Claim 11**: The transmitting unit transmits the DCI to a communication device. The control unit identifies the availability indicator of the received DCI based on the determined number of bits. The base station according to claim 7 or 8. **Claim 12**: The transmitting unit transmits a Tracking Reference Signal (TRS) based on the TRS resource set based on the values of the bits of the bitmap of the determined number of bits. The base station according to claim 7 or 8. **Claim 13** A communication method executed by a communication device (100), comprising: receiving a System Information Block (SIB) from a base station (200); determining the number of bits of a bitmap of an availability indicator of a Tracking Reference Signal (TRS) in Downlink Control Information (DCI). In the step of determining, if a TRS resource set configuration, which is a list of TRS resource sets, is included in the SIB, the number of bits is determined based on an identifier associated with the TRS resource set; if the TRS resource set configuration is not included in the SIB, the number of bits is determined to be 0. Communication method. **Claim 14**: The identifier is included in the TRS resource set configuration. The communication method according to claim 13. **Claim 15**: The DCI is accompanied by a Cyclic Redundancy Check (CRC) scrambled by a Paging Radio Network Temporary Identifier (P-RNTI). The communication method according to claim 13 or 14. **Claim 16**: The DCI is accompanied by a Cyclic Redundancy Check (CRC) scrambled by a Paging Early Indicator - Radio Network Temporary Identifier (PEI-RNTI). The communication method according to claim 13 or 14. **Claim 17**: In the receiving step, the DCI is received from the base station, and in the determining step, the availability indicator of the received DCI is identified based on the determined number of bits. The communication method according to claim 13 or 14. According to claim 18, in the receiving step, based on the values of the bits of the bitmap of the determined number of bits, a TRS based on the TRS resource set is received. The communication method according to claim 13 or 14.

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