Terminal and wireless communication method

Abstract

To provide a terminal and a wireless communication method that appropriately control operations related to a TRS.SOLUTION: In a wireless communication system, a terminal 10 includes a receiving unit 101 that receives system information, and a control unit 103 that sets a resource or period for a tracking reference signal based on the system information. The receiving unit 101 receives indication information indicating that the tracking reference signal is available in the resource and / or period. The control unit 103 controls a timer related to a valid period of the indication information based on whether the system information is area-specific when a cell to camp on is re-selected.SELECTED DRAWING: Figure 12

Description

[Technical field]

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

[0002] The Third Generation Partnership Project (3GPP), an international standardization organization, has specified Release 15 of New Radio (NR), a fifth generation (5G) RAT, as a successor to Long Term Evolution (LTE), a 3.9th generation radio access technology (RAT), and LTE-Advanced, a fourth generation RAT (for example, Non-Patent Document 1). LTE and / or LTE-Advanced are also called Evolved Universal Terrestrial Radio Access (E-UTRA). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] 3GPP TS 38.300 V15.2.0 (2018-06) Summary of the Invention [Problem to be solved by the invention]

[0004] Currently, 3GPP is considering performing synchronization in the time domain and / or frequency domain (hereinafter referred to as "time / frequency synchronization") using a tracking reference signal (hereinafter referred to as "Tracking Reference Signal (TRS)"). For example, it is expected that a terminal in an idle state or in an inactive state will use the TRS instead of a synchronization signal to perform time / frequency synchronization before a paging occasion (PO), thereby reducing the power consumption of the terminal.

[0005] It is also being considered to make it possible to control whether or not to actually transmit a TRS during the resources and / or period set for the TRS by notifying the terminal of instruction information regarding the availability of the TRS during the resources and / or period set for the TRS (hereinafter referred to as "TRS availability instruction") and / or by setting a validity period for the instruction information.

[0006] The present disclosure has been made in consideration of the above circumstances, and one of its objectives is to provide a terminal and a wireless communication method capable of appropriately controlling operations related to TRS. [Means for solving the problem]

[0007] A terminal according to one embodiment of the present disclosure includes a receiving unit that receives system information and a control unit that sets resources and / or a period for a tracking reference signal based on the system information, wherein the receiving unit receives indication information indicating that the tracking reference signal is available in the resources and / or the period, and the control unit controls a timer for a validity period of the indication information based on whether the system information is area-specific when reselecting a cell to camp on. Effect of the Invention

[0008] According to one aspect of the present disclosure, it is an object to provide a terminal and a wireless communication method capable of appropriately controlling operations related to TRS. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram illustrating an example of an overview of a wireless communication system according to an embodiment of the present invention. [Diagram 2] FIG. 11 is a diagram showing an example of obtaining an SI message according to the present embodiment. [Diagram 3] 3A and 3B are diagrams showing an example of a TRS availability indication and a validity period according to the present embodiment. [Figure 4] A figure showing another example of a TRS availability indication and validity period according to the embodiment. [Diagram 5] FIG. 11 is a diagram showing an example of a TRS-related operation at the time of cell reselection according to the present embodiment. [Figure 6] FIG. 11 is a diagram showing another example of TRS-related operations at the time of cell reselection according to the present embodiment. [Figure 7] 7A and 7B are diagrams showing an example of the operation during activation of the validity timer according to this embodiment. [Figure 8] FIG. 11 is a diagram illustrating an example of an SI update procedure according to the present embodiment. [Figure 9] 11 is a diagram showing an example of a control operation of a validity period of a TRS availability instruction according to the present embodiment. FIG. [Figure 10] A figure showing another example of the control operation of the validity period of a TRS availability instruction in this embodiment. [Figure 11] FIG. 2 is a diagram illustrating an example of the hardware configuration of each device in the wireless communication system according to the present embodiment. [Figure 12] FIG. 2 is a diagram illustrating an example of a functional block configuration of a terminal according to the present embodiment. [Figure 13] FIG. 2 is a diagram illustrating an example of a functional block configuration of a base station according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the present embodiment will be described with reference to the accompanying drawings. In order to facilitate understanding of the description, the same components in each drawing are denoted by the same reference numerals as much as possible, and duplicated description will be omitted.

[0011] Fig. 1 is a diagram showing an example of an overview of a wireless communication system according to the present embodiment. As shown in Fig. 1, the wireless communication system 1 may include a terminal 10, a base station 20, and a core network 30. Note that the numbers of terminals 10 and base stations 20 shown in Fig. 1 are merely examples and are not limited to the numbers shown in the figure.

[0012] The radio access technology (RAT) of the wireless communication system 1 is assumed to be, for example, NR, but is not limited thereto, and various RATs such as, for example, RATs of the sixth generation or later can be used.

[0013] The terminal 10 is a specific terminal or device, such as a smartphone, a personal computer, an in-vehicle terminal, an in-vehicle device, a stationary device, a telematics control unit (TCU), etc. The terminal 10 may be called a user equipment (UE), a mobile station (MS), a terminal (User Terminal), a radio apparatus, a subscriber terminal, an access terminal, etc. The terminal 10 may be of a mobile type or a fixed type. The terminal 10 is configured to be capable of communicating using, for example, NR as a RAT.

[0014] The base station 20 forms one or more cells C and communicates with the terminal 10 using the cells. The cell C may be interchangeably referred to as a serving cell, a carrier, a component carrier (CC), or the like. For example, the base station 20 may set one primary cell and one or more secondary cells for the terminal 10 and communicate with the terminal 10 (also referred to as carrier aggregation). That is, the one or more cells C include at least a primary cell, and may also include a secondary cell.

[0015] Furthermore, one or more bandwidth parts (BWPs) may be set for one cell C. Here, the BWPs mainly used when the terminal 10 initially accesses the cell are also referred to as an initial downlink BWP (Initial DL BWP) and an initial uplink BWP (Initial UL BWP). For example, the base station 20 may broadcast information used to set the frequency position, bandwidth, subcarrier spacing, and / or cyclic prefix for each of the initial downlink BWP and the initial uplink BWP by including them in the system information.

[0016] The base station 20 may be called a gNodeB (gNB), en-gNB, a Next Generation-Radio Access Network (NG-RAN) node, a low-power node, a Central Unit (CU), a Distributed Unit (DU), a gNB-DU, a Remote Radio Head (RRH), an Integrated Access and Backhaul / Backhauling (IAB) node, etc. The base station 20 is not limited to one node, and may be configured with multiple nodes (for example, a combination of a lower node such as a DU and an upper node such as a CU).

[0017] The core network 30 is, for example, a core network (5G Core Network: 5GC) compatible with NR, but is not limited to this. An apparatus on the core network 30 (hereinafter also referred to as a "core network apparatus") performs mobility management such as paging and location registration of the terminal 10. The core network apparatus may be connected to the base station 20 via a predetermined interface (for example, an S1 or NG interface).

[0018] The core network device may include, for example, at least one of an Access and Mobility Management Function (AMF) that manages C-plane information (e.g., information related to access and mobility management, etc.) and a User Plane Function (UPF) that controls the transmission of U-plane information (e.g., user data).

[0019] In the wireless communication system 1, a terminal 10 receives a downlink (DL) signal and / or transmits an uplink (UL) signal from a base station 20. One or more cells C are configured in the terminal 10, and at least one of the configured cells is activated. The maximum bandwidth of each cell is, for example, 20 MHz or 400 MHz.

[0020] Furthermore, the terminal 10 performs a cell search based on a synchronization signal (e.g., a Primary Synchronization Signal (PSS) and / or a Secondary Synchronization Signal (SSS)) from the base station 20. The cell search is a procedure in which the terminal 10 acquires time and frequency synchronization in a cell and detects an identifier of the cell (e.g., a physical layer cell ID).

[0021] A block including at least one of the above synchronization signal, broadcast channel (e.g., Physical Broadcast Channel (PBCH)), and demodulation reference signal (DMRS) of the broadcast channel is also called a synchronization signal block (SSB), SS / PBCH block, etc. One or more SSBs constitute one SS burst, and one or more SS bursts may constitute one SS burst set. The SS burst set may be transmitted at a predetermined period (e.g., 20 ms (2 radio frames)). In the case of multi-beam operation, SSBs with different indices correspond to different beams, and may be transmitted by sequentially switching the beam direction by beam sweeping.

[0022] The terminal 10 determines a search space and / or a control resource set (CORESET) based on parameters (hereinafter referred to as "RRC parameters") included in a Radio Resource Control (RRC) message, and monitors downlink control information (DCI) transmitted via a downlink control channel (e.g., a physical downlink control channel (PDCCH)) within the search space associated with the CORESET. The RRC message may include, for example, an RRC setup message, an RRC reconfiguration message, an RRC resume message, system information, etc.

[0023] DCI monitoring refers to the terminal 10 blind decoding of PDCCH candidates in a search space set in an assumed DCI format. The number of bits (also referred to as size, bit width, etc.) of the DCI format is predefined or derived according to the number of bits of a field included in the DCI format. The terminal 10 detects DCI for the terminal 10 based on the number of bits of the DCI format and a specific Radio Network Temporary Identifier (RNTI) used for scrambling (hereinafter referred to as "CRC scrambling") of Cyclic Redundancy Check (CRC) bits (also referred to as CRC parity bits) of the DCI format. DCI monitoring is also called PDCCH monitoring, monitor, etc. A period during which DCI monitoring is performed is also called a PDCCH monitoring occasion.

[0024] The search space set is a collection of one or more search spaces, and may include a search space set used in common by one or more terminals 10 (hereinafter referred to as a "Common search space (CSS) set") and a terminal-specific search space set (UE-specific search space (USS) set). The search space set used for PDCCH monitoring of the terminal 10 may be configured in the terminal 10 using higher layer parameters (for example, RRC Information Element (IE) "SearchSpace", RRC IE "pagingSearchSpace", RRC IE "searchSpaceSIB1", RRC IE "searchSpaceOtherSystemInformation", etc.). The terminal 10 detects DCI that is CRC-scrambled by a specific RNTI (e.g., Cell(C)-RNTI, Paging(P)-RNTI, etc.) by PDCCH monitoring using a search space set, and controls reception of a PDSCH scheduled using the DCI and / or transmission of an uplink shared channel (e.g., a physical uplink shared channel (PUSCH)).

[0025] (System Information) The system information broadcast in cell C may include a Master Information Block (MIB) and / or one or more System Information Blocks (SIB). The MIB is broadcast via a Broadcast Channel (BCH). The MIB and SIB1 are also called Minimum System Information, and SIB1 is also called Remaining Minimum System Information (RMSI). The SIB1 is broadcast via a Downlink Shared Channel (DL-SCH). SIBx (x=any character string such as 2, 3, ...) other than SIB1 is also called Other System Information (OSI). The SIB1 is cell-specific, and the SIBx other than SIB1 is cell-specific or area-specific including one or more cells. The area is also called a system information area, etc.

[0026] One or more SIBx are mapped to a system information (SI) message, and the SI message is broadcast via DL-SCH. Each SI message may be associated with a periodically occurring time domain window (hereinafter, referred to as an "SI window") and transmitted within the SI window. Note that the BCH and DL-SCH may be interchangeably referred to as the PBCH and the Physical Downlink Shared Channel (PDSCH), respectively.

[0027] FIG. 2 is a diagram showing an example of acquiring SI messages according to the present embodiment. In FIG. 2, as an example, it is assumed that SIBx and SIBy are mapped to SI message #0, and SIBz is mapped to SI message #1. Here, x, y, and z are arbitrary character strings such as 2, 3, ..., and may be identifiers of SIB types (hereinafter, referred to as "SIB types"). SI messages #0 and #1 may be broadcast at a predetermined cycle, or may be broadcast on demand in response to a request from terminal 10. In addition, each SI message #0 may be the same within an update period (modification). Note that FIG. 2 is merely an example, and the number of SI messages, the number of SIBs mapped to each SI message, whether SIBx, SIBy, and SIBz are area-specific or cell-specific, and the like are not limited to those shown in the figure.

[0028] For example, as shown in Fig. 2, the terminal 10 detects an SSB and acquires an MIB broadcasted via a PBCH. The terminal 10 monitors a search space set (e.g., Type0-PDCCH CSS set) set for SIB1, detects a DCI CRC-scrambled with a specific RNTI (e.g., System Information (SI)-RNTI), and receives SIB1 via a PDSCH scheduled by the DCI. The search space set for the SIB1 may be set based on a parameter in the MIB, but is not limited to this.

[0029] SIB1 may also include at least one of the following: Information about each SI message (e.g., each "schedulingInfo" in the RRC IE "schedulingInfoList") - Identification of the area to which the area-specific SIB belongs (e.g., the RRC IE "systemInformationAreaID") · Information about the length of the SI window (eg RRC IE "si-WindowLength"), where said length is indicated for example in number of slots. Information regarding the periodicity of each SI message (eg "si-Periodicity" in the RRC IE "schedulingInfo"), where the periodicity is indicated for example in number of radio frames. Information on each SIB mapped to each SI message (e.g., each "SIB-TypeInfo" in "SIB-Mapping" in the RRC IE "schedulingInfo"), where the information on each SIB may include at least one of information on the SIB type (e.g., RRC IE "type"), information on the version or number of updates of each SIB (hereinafter referred to as "version information", e.g., RRC IE "valueTag"), and information indicating that each SIB is area-specific (e.g., RRC IE "areaScope"). Note that not including information indicating that each SIB is area-specific may indicate that each SIB is cell-specific.

[0030] Terminal 10 monitors a search space set (e.g., Type 0A-PDCCH CSS set) configured for OSI, detects DCI CRC-scrambled with a specific RNTI (e.g., SI-RNTI), receives SI messages #0 and #1 via a PDSCH scheduled by the DCI, and performs operations based on the OSI (here, SIBx, SIBy, and SIBz) contained in SI messages #0 and #1, respectively.

[0031] For example, in FIG. 2, SIBx and SIBy included in SI message #0 are area-specific, and SIBz included in SI message #1 is cell-specific. In addition, the version information of SIB1 (for example, RRC IE "valueTag") indicates that SIBx and SIBz have been updated once and have a version of v1, and SIBy has not been updated and has a version of v0. For example, the terminal 10 may determine whether the stored SIBx is valid based on the version indicated by the version information and the version of SIBx stored in the terminal 10. For example, when the "v1" indicated by the valueTag in SIB1 matches the version of the stored SIBz, the terminal 10 may not need to re-receive the SI message #1 including SIBz. On the other hand, when the version "v1" indicated by the valueTag in SIB1 does not match the version of the stored SIBx, the terminal 10 may re-receive the SI message #0 including SIBx. In this way, the valuetag of SIBx, SIBy, and SIBz may be counted up by 1 every time the contents are changed.

[0032] (paging) In paging, when the terminal 10 is in an idle state or an inactive state, a message for setting up a connection at the initiative of the network (hereinafter, a "paging message") is transmitted to the terminal 10. In addition, in paging, for example, a short message used for notifying a change in system information and / or a public warning (e.g., Earthquake and Tsunami Warning System (ETWS), Commercial Mobile Alert Service (CMAS), etc.) is transmitted to the terminal 10. The short message may be transmitted to the terminal 10 regardless of the state of the terminal 10 (e.g., an idle state, an inactive state, a connected state, etc.).

[0033] Here, the idle state is a state in which an RRC layer connection (hereinafter referred to as an "RRC connection") between the terminal 10 and the base station 20 has not been established, and is also called RRC_IDLE, idle mode, RRC idle mode, etc. The terminal 10 in the idle state receives system information broadcast in the cell on which it is camped. When an RRC connection is established, the terminal 10 in the idle state transitions to the connected state.

[0034] The inactive state is a state in which the RRC connection is established but suspended, and is also called an RRC_INACTIVE state, an inactive mode, an RRC inactive mode, etc. The terminal 10 in the inactive state receives system information broadcast in the cell in which it is camped. The terminal 10 in the inactive state transitions to a connected state when the RRC connection is resumed, and transitions to an idle state when the RRC connection is released.

[0035] The connected state is a state in which the RRC connection is established, and is also called an RRC_CONNECTED state, a connected mode, an RRC connected mode, etc. The terminal 10 in the connected state transitions to an idle state when the RRC connection is released, and transitions to an inactive state when the RRC connection is suspended.

[0036] A terminal 10 in an idle state or an inactive state receives a paging message at a paging occasion (PO), which is a period of a predetermined cycle, by discontinuous reception (DRX). A PO is associated with a paging frame (PF) of a predetermined cycle. A PF may be configured, for example, by a radio frame identified by a specific number (for example, a system frame number (SFN)). A PO may be configured, for example, by a subframe, a slot, or a symbol of a predetermined cycle.

[0037] Here, a radio frame may be composed of 10 subframes, and one subframe may be 1 ms. A slot is a time unit based on numerology (e.g., subcarrier spacing (SCS)), and for example, when SCS=15 kHz, one slot may be equal to one subframe. One slot may include a predetermined number of symbols (e.g., 14 symbols).

[0038] For example, a PF may be set in the terminal 10 in a period (hereinafter referred to as a "paging cycle") determined based on the DRX period, and one PO may be set for each PF. That is, a PO may be set in the paging cycle in the terminal 10. A PO may include one or more PDCCH monitoring opportunities. In the following, a PO is exemplified as a paging period, but the present invention is not limited to this, and it goes without saying that other terms equivalent to a PF or a paging period may be used.

[0039] The terminal 10 may monitor a search space set (e.g., Type2-PDCCH CSS set) configured by a higher layer parameter (e.g., RRC IE "pagingSearchSpace"), and detect DCI (hereinafter also referred to as "paging DCI") that is CRC scrambled by a specific RNTI (e.g., paging (P)-RNTI). The terminal 10 receives a paging message via a PDSCH scheduled using the paging DCI. Here, information indicating the specific RNTI (e.g., P-RNTI) may be configured in the terminal 10 by higher layer signaling.

[0040] Furthermore, the terminal 10 may receive a short message transmitted by the paging DCI. In this manner, the paging DCI is used for scheduling the PDSCH used for transmitting the paging message and / or for transmitting the short message.

[0041] (TRS) It is being considered that the terminal 10 performs time / frequency synchronization using TRS. For example, the terminal 10 in an idle state or inactive state will in principle enter a sleep state in which power consumption is reduced between POs by DRX, but will enter a wake-up state for time / frequency synchronization during a predetermined period before the next PO. Specifically, it is assumed that the terminal 10 will enter a deep sleep state from the previous PO until the predetermined period, and enter a microsleep state after the predetermined period until the next PO.

[0042] Here, the deep sleep state is a state in which power consumption is further reduced than in the microsleep state. For example, when time / frequency synchronization is performed using a TRS arranged at a time position closer to the next PO than the SS burst, the period of the deep sleep state of the terminal 10 between POs can be made longer than when time / frequency synchronization is performed using the SS burst. For this reason, it is expected that the power consumption of the terminal 10 will be reduced by time / frequency synchronization using a TRS.

[0043] Here, the TRS is, for example, but not limited to, a Channel State Information-Reference Signal (CSI-RS). The TRS may be rephrased as CSI-RS, non-zero power-CSI-RS (NZP-CSI-RS), TRS / CSI-RS, reference signal, etc.

[0044] The purpose of the TRS may be, for example, at least one of the above-mentioned time / frequency synchronization, tracking, path delay spread, Doppler spread estimation, and loop convergence. Tracking refers to tracking and / or compensating for time and / or frequency variations of a local oscillator of the terminal 10. The TRS may be any signal used for the above-mentioned purposes. Furthermore, when the TRS is set in the terminal 10, the terminal 10 can achieve time / frequency synchronization without referring to the SS burst.

[0045] The resources for TRS as described above (hereinafter "TRS resources" may be composed of, for example, a set (hereinafter "NZP-CSI-RS resource set") of one or more resources for NZP-CSI-RS (hereinafter referred to as "NZP-CSI-RS resources"). The TRS resources may be composed of a predetermined number of symbols and a predetermined number of subcarriers in a predetermined number of slots of a predetermined period (hereinafter referred to as a "TRS period", for example, a period of 10, 20, 40 or 80 ms). A period of the predetermined period including the TRS resources (for example, the above-mentioned predetermined number of slots) is also referred to as a TRS opportunity, a TRS / CSI-RS opportunity, etc.

[0046] The terminal 10 receives information (hereinafter, referred to as "TRS resource / opportunity information") regarding a TRS resource and / or a TRS opportunity (hereinafter, referred to as "TRS resource / opportunity"). The terminal 10 may set the TRS resource / opportunity based on the TRS resource / opportunity information from the base station 20.

[0047] Note that the TRS resource / opportunity information for the terminal 10 in the idle state or inactive state may be at least a part of the TRS resource / opportunity information for the terminal 10 in the connected state. The TRS resource / opportunity information for the terminal 10 in the connected state (e.g., RRC IE "NZP-CSI-RS ResourceSet", RRC IE "CSI-ResourceConfig", etc.) may be included in an RRC message (e.g., an RRC Setup message for establishing an RRC connection or an RRC Reconfiguration message for reconfiguring an RRC connection).

[0048] On the other hand, the TRS resource / opportunity information for the terminal 10 in the idle state or inactive state may be included in system information (e.g., SIB1 or SIBx) and / or an RRC message (e.g., an RRC release message (RRCRelease message) used to release or suspend an RRC connection, etc.). For example, the TRS resource / opportunity information for the terminal 10 in the idle state or inactive state may include information on the power of the TRS (e.g., powerControlOffsetSS indicating the power offset of the TRS relative to the SSS), information on the scrambling ID of the TRS (scramblingID), information on the time domain resource to which the TRS is mapped (e.g., firstOFDMSymbolInTimeDomain indicating the first symbol for the TRS), and information on the frequency domain resource to which the TRS is mapped (e.g., startingRB indicating the starting resource block of the TRS, nrofRBs indicating the number of resource blocks of the TRS, etc.).

[0049] Furthermore, the TRS resource / opportunity information for the terminal 10 in the idle or inactive state may include information on quasi co-location (QCL), and an index of an SSB may be set. That is, the terminal 10 may identify a quasi-co-location relationship between a TRS transmitted in a corresponding TRS resource / opportunity and the SSB by setting an index of the SSB as the TRS resource / opportunity information. Here, quasi-co-location may indicate that the large-scale properties of a signal (e.g., a TRS) may be assumed to be the same in whole or in part as the large-scale properties of another signal (e.g., an SSB). For example, two antenna ports being quasi-co-located may indicate that a signal (or a channel) transmitted at one antenna port may be estimated from a signal (or a channel) transmitted at another antenna port. Here, for example, the wide area characteristics may include Doppler spread, Doppler shift, delay spread, average gain, and / or average delay.

[0050] Here, the index of the SSB set as information on quasi-collocation may be the index of the SSB (also referred to as Cell-Defining SSB) associated with SIB1. That is, when information on quasi-collocation is set for the terminal 10 as TRS resource / opportunity information for the terminal 10 in an idle state or an inactive state, the index of the SSB associated with SIB1 may be set. The terminal 10 may consider that the TRS transmitted in the corresponding TRS resource / opportunity and the SSB are quasi-collocated (have a quasi-collocated relationship) based on the index of the SSB associated with SIB1 set by the base station 20. Here, SIB1 may be referred to as RMSI (Remaining Minimum System Information).

[0051] Additionally, at least one parameter used to configure TRS resources / opportunities for a terminal 10 in an idle or inactive state may be predetermined in a specification. The parameter may be, for example, at least one of information about the BWP (e.g., bwp-id indicating a BWP ID), information about the TRS resource in the time domain (e.g., resourceType indicating aperiodic, semi-persistent, or periodic), information about repetition (e.g., repetition indicating on or off of repetition), aperiodicTriggeringOffset indicating the time offset between the triggering of aperiodic TRS and the TRS resource, trs-Info indicating that the antenna ports of all NZP CSI-RS resources in a CSI-RS resource set are the same, information about the power of the TRS (e.g., powerControlOffset indicating the power offset of the PDSCH for the NZP-CSI-RS), information about the number of antenna ports for the TRS (e.g., nrofPorts indicating the number of ports), information about the time domain resource (e.g., firstOFDMSYmbolInTimeDomain2 indicating the time domain allocation in a resource block), cdm-Type indicating the type of Code Division Multiplexing (CDM) for the TRS, and information about the density of the TRS resource (e.g., density). As mentioned above, the TRS here may be rephrased as NZP CSI-RS, etc.

[0052] Furthermore, the TRS resource / opportunity information may include parameters commonly used in the configuration of multiple TRS resources / opportunities and / or parameters used independently. An index may be assigned to each of the multiple TRS resources / opportunities. For example, an index may be assigned to each of parameters (e.g., a set of parameters) used independently in the configuration of multiple TRS resources / opportunities. In other words, an index may not be assigned to a parameter commonly used in the configuration of multiple TRS resources / opportunities. In this way, the TRS resources / opportunities may be controlled based on higher layer parameters (e.g., RRC parameters and / or MAC CE, etc.) and / or physical layer parameters (e.g., DCI format, etc.).

[0053] It is being considered to signal instruction information regarding the availability of TRS in the above-mentioned TRS resources / opportunities (hereinafter referred to as "TRS availability instruction") from the base station 20 to the terminal 10. Note that the availability of TRS can be rephrased as the possibility of transmitting TRS in the TRS resources / opportunities, and vice versa. In the following, "TRS is or is not actually transmitted (from the base station 20)" can be rephrased as "TRS is or is not available (to the terminal 10)."

[0054] The TRS availability indication may be comprised of a predetermined number of bits, where a first value of the bit (e.g., "1") indicates that the TRS is available (i.e., is actually transmitted by the base station 20) and a second value of the bit (e.g., "0") indicates that the TRS is not available (i.e., is not actually transmitted by the base station 20). The predetermined number of bits that make up the TRS availability indication may also indicate whether the TRS is available (i.e., is actually transmitted by the base station 20) at a particular TRS resource / opportunity. For example, when the TRS resources are composed of an NZP-CSI-RS resource set including NZP-CSI-RS resources #0 to #3, a first bit value (e.g., "000") may indicate that the TRS is not transmitted over the entire NZP-CSI-RS resource set, a second bit value (e.g., "001" to "110") may indicate that the TRS is transmitted over an NZP-CSI-RS resource that is part of the NZP-CSI-RS resource set and is indicated by the second bit value, and a third bit value (e.g., "111") may indicate that the TRS is transmitted over the entire NZP-CSI-RS resource set.

[0055] Also, for example, base station 20 may configure the correspondence between the value (for example, each of "000", "001" to "110", and / or "111") set as the TRS availability indication and the NZP-CSI-RS resource set, using higher layer signaling such as an RRC message. Here, #0 to #3 in NZP-CSI-RS resources #0 to #3 may correspond to indexes assigned to TRS resources / opportunities. For example, as described above, an index may be assigned to each parameter (for example, a set of parameters) used independently for configuring multiple TRS resources / opportunities, and the index may be indicated in response to the TRS availability indication (or a bit value), thereby identifying each of the multiple TRS resources / opportunities. That is, terminal 10 may identify the TRS resource / opportunity based on a parameter commonly used for configuring multiple TRS resources / opportunities and a parameter of the TRS resource / opportunity corresponding to the index indicated by the TRS availability indication (or a bit value). The terminal 10 may also determine TRS availability at the identified TRS resource / opportunity based on the TRS availability indication (or bit value).

[0056] Alternatively, the TRS availability indication may indicate that the TRS is available (i.e., is actually transmitted from the base station 20). For example, the TRS availability indication may be notified (or set to true) to the terminal 10 only when the TRS is actually transmitted from the base station 20 in the TRS resource / opportunity, and the TRS availability indication may not be notified to the terminal 10 when the TRS is not actually transmitted. Conversely, the TRS availability indication may be notified to the terminal 10 only when the TRS is not actually transmitted.

[0057] Such signaling of the TRS availability indication may use physical layer (L1) based signaling (hereinafter referred to as "L1 signaling") or RRC layer signaling (hereinafter referred to as "RRC signaling").

[0058] When L1 signaling is used, the TRS availability indication may be a value of a predetermined field of a DCI, or may be a specific signal (e.g., SSB or TRS, etc.) or a specific sequence of the specific signal. The DCI including the TRS availability indication may be a DCI used for scheduling a PDSCH that carries a paging message (also called a "paging DCI"), or may be a DCI including a field used for a paging early indication (PEI) (also called a "PEI DCI"). For example, the paging DCI and / or the PEI DCI may be CRC scrambled by a specific RNTI (e.g., P-RNTI) configured using higher layer signaling such as an RRC message.

[0059] The PEI is indication information regarding a paging target in a PO. The terminal 10 determines whether the terminal 10 or a group (or subgroup) to which the terminal 10 belongs is a paging target in a PO based on the PEI (or based on whether the PEI is detected). The terminal 10 can reduce power consumption by skipping PDCCH monitoring and / or reception and / or decoding of a paging message for a PO that is not a paging target. Note that the PEI is not limited to a value of a predetermined field of the DCI, and may be a specific signal (for example, SSB or TRS) or a specific sequence of the specific signal. The specific signal may be used as a TRS availability indication.

[0060] When RRC signaling is used, the TRS availability indication may be a parameter or IE value included in system information (e.g., SIB1 or a SIBx other than SIB1) or an RRC message (e.g., an RRC release message used to release an RRC connection).

[0061] The period during which such a TRS availability indication is considered valid (hereinafter, referred to as "validity time") may be determined in advance in a specification. Alternatively, information regarding the validity time (hereinafter, referred to as "validity time information") may be signaled from the base station 20 to the terminal 10. The validity time information may be included in, for example, system information, an RRC message, or a DCI (for example, the above-mentioned paging DCI or PEI DCI). The validity time may be indicated by the number of a predetermined time unit (for example, radio frames, slots, subframes, or symbols), may be indicated by time (for example, milliseconds), or may be indicated by the number of paging cycles, POs, or DRX periods. If the terminal receives a TRS availability indication within the validity time, it does not need to reacquire another TRS availability indication within the validity time.

[0062] The validity period may be controlled using a timer (hereinafter referred to as a "validity timer"). The validity timer may be started, for example, based on detection of a TRS availability indication, or based on detection of system information, paging DCI or PEI DCI, or based on an SSB, SS burst or PO. The validity timer may expire after a period predefined in the specification or a period indicated by the validity period information. If the terminal 10 does not receive a TRS availability indication before the validity timer expires, the terminal 10 may assume that TRS is not available for the corresponding TRS resource / opportunity.

[0063] 3(A) and (B) are diagrams showing an example of the TRS availability indication and the validity period according to the present embodiment. For example, in FIG. 3(A) and (B), the terminal 10 is in a deep sleep state from the end timing T0 of the previous PO to the start timing T1 of the reception of the SS burst, and is in a microsleep state from the end timing T3 of the SS burst to the start timing T4 of the next PO, except for the TRS availability indication and the reception period of the TRS. The same applies to the timings T5 to T9 as to the timings T0 to T4. Note that FIG. 3(A) and (B) are merely examples, and the period in which the terminal 10 is in a deep sleep state and / or a microsleep state can be changed as appropriate.

[0064] For example, in FIG. 3(A), a TRS availability indication is included in the PEI DCI. The terminal 10 detects the PEI DCI by monitoring in a PDCCH monitoring opportunity set for the PEI. The terminal 10 determines whether or not a TRS is transmitted before a subsequent PO based on the TRS availability indication in the PEI DCI. For example, the terminal 10 determines that a TRS is transmitted in a TRS resource / opportunity before the next PO based on the PEI DCI detected at timing T2. On the other hand, the terminal 10 determines that a TRS is not transmitted in a TRS resource / opportunity before the next PO based on the PEI DCI detected at timing T8.

[0065] As shown in Fig. 3(A), the validity period of the TRS availability indication indicating that the TRS is available may be from the detection timing of the PEI DCI including the TRS availability indication to the start timing of the next PO. Note that in Fig. 3(A), a timer may be started at the detection timing T2 of the PEI DCI, and the timer may be stopped or expire at the start timing T4 of the next PO.

[0066] On the other hand, Fig. 3(B) differs from Fig. 3(A) in that a TRS availability indication is included in the paging DCI. In Fig. 3(B), the terminal 10 may operate by replacing the PEI DCI in Fig. 3(A) with a paging DCI. As shown in Fig. 3(B), the valid period of the TRS availability indication may be from the end timing of the PO in which the paging DCI including the TRS availability indication is detected to the start timing of the next PO. According to the TRS availability indication using the paging DCI, even if the PEI is not transmitted, it is possible to flexibly change whether or not to transmit the TRS in the configured TRS resource.

[0067] Figures 4(A) and (B) are diagrams showing other examples of TRS availability indications and validity periods according to the present embodiment. Figures 4(A) and (B) differ from Figures 3(A) and 3(B) in that the validity period of the TRS availability indication spans one or more POs.

[0068] In Fig. 4(A), the TRS availability indication included in the paging DCI will be described with a focus on differences from Fig. 3(B). The validity period spanning one or more POs can also be applied to the TRS availability indication using the PEI described in Fig. 3(A). For example, in Fig. 4(A), the validity period of the TRS availability indication may be four paging cycles. For example, as shown in Fig. 4(A), when a paging DCI including a TRS availability indication is detected in a certain PO, the TRS availability indication may indicate whether or not a TRS is transmitted in a TRS resource set from the PO for four paging cycles.

[0069] In FIG. 4B, an example of a TRS availability indication in system information (e.g., SIB1 or SIBx) is shown. The terminal 10 may determine whether a TRS is transmitted in the TRS resource set before each PO based on the availability indication in the system information. The TRS availability indication using the system information is suitable for cases where the validity period is relatively long.

[0070] 3 and 4, the PDCCH monitoring opportunity for the DCI used for the TRS availability indication may be determined based on at least one time position of the SS burst, the SS burst set, and the PO. For example, the PDCCH monitoring opportunity may be determined based on the time position and a time offset relative to the time position. The time offset may be based on a subcarrier spacing of an SSB or a bandwidth part (BWP).

[0071] (TRS related operations) As described above, when it is possible to control whether or not to actually transmit a TRS in a TRS resource / period by notifying the terminal 10 of a TRS availability indication and / or by providing a validity period for the TRS availability indication, it is desirable to appropriately control operations related to TRS (hereinafter, "TRS-related operations"). In the following, the TRS-related operations in the cases of (1) reselection of a cell on which the terminal 10 camps (hereinafter, "cell reselection"), (2) when a validity timer is running, and (3) when system information is used to indicate the availability of TRS will be described.

[0072] In the following, SIBx (x is an identifier of an SIB type such as 2, 3, 4, etc.) other than SIB1 will be described as an example of system information, but the system information in this embodiment is not limited to SIBx. In the following, the terminal 10 is assumed to be in an idle state or an inactive state, but this does not prevent application in a connected state.

[0073] (1) TRS-related operations during cell reselection The TRS-related operation of the terminal 10 during cell reselection will be described. The terminal 10 receives SIBx during cell selection or cell reselection. It is assumed that the SIBx is either area-specific or cell-specific. When the terminal 10 performs cell reselection between cells in the same area, it is not necessary to re-receive the area-specific SIBx. It is assumed that the SIBx used for setting the TRS resource / opportunity is either area-specific or cell-specific.

[0074] Therefore, when the terminal 10 reselects a cell to camp on, it controls the validity timer for the validity period of the TRS availability indication indicating that TRS is available in the TRS resource / opportunity based on whether the SIBx used to configure the TRS resource / opportunity is area-specific or not.

[0075] Fig. 5 is a diagram showing an example of TRS-related operations at the time of cell reselection according to the present embodiment. For example, in Fig. 5, it is assumed that cells #0 and #1 are included in area #1, and cells #2 and #3 are included in area #2. In Fig. 5, terminal 10 camps on cell #0 and receives SIBx specific to area #1 from base station 20 that forms cell #0. Terminal 10 may set TRS resources / opportunities based on TRS resource / opportunity information included in the SIBx.

[0076] Furthermore, the terminal 10 camped on the cell #0 receives a TRS availability indication. The TRS availability indication may be included in any of the above-mentioned area #1 specific SIBx, paging DCI, PEI DCI, TRS as PEI, or RRC message. The terminal 10 starts a valid timer for the TRS availability indication at timing T1.

[0077] For example, in Fig. 5, the terminal 10 reselects cell #1 that belongs to the same area #1 as cell #0 at timing T2. Since the SIBx received in cell #0 is specific to area #1 and the reselected cell #1 belongs to the same area #1 as cell #0, the terminal 10 does not stop the validity timer at timing T2 and continues running the TRS-related operation. Furthermore, since the terminal 10 has received the SIBx specific to area #1 in cell #0, it does not need to receive the SIBx again when reselecting cell #1.

[0078] 5, the terminal 10 reselects cell #2 that belongs to area #2 different from cell #1 at timing T3. Since the reselected cell #2 belongs to area #2 different from area #1 to which cell #1 belongs, the terminal 10 stops the validity timer at timing T3 without waiting for expiration at timing T4. Note that stopping the validity timer may be rephrased as resetting, discarding, or the like.

[0079] When the terminal 10 reselects the cell #2, the area IDs to which the cells #1 and #2 belong are different, so the terminal 10 receives an SIBx from the base station 20 that forms the cell #2. Note that in FIG. 5, the SIBx is specific to the area #2, but is not limited to this. The terminal 10 may set a TRS resource / opportunity based on the TRS resource / opportunity information included in the SIBx. The terminal 10 camped on the cell #2 may receive a TRS availability indication and start a validity timer for the TRS availability indication at timing T3. The validity timer expires at timing T5, and the validity period of the TRS availability indication received in the cell #2 ends.

[0080] In this way, when the SIBx including the TRS resource / opportunity information is area-specific, if the terminal 10 performs cell reselection between cells #0 and #1 belonging to the same area #1, the validity timer continues without being reset. On the other hand, if the terminal 10 performs cell reselection between cells #1 and #2 belonging to different areas #1 and #2, respectively, the validity timer is reset. Therefore, even if the terminal 10 moves between cells belonging to the same area or between cells belonging to different areas, the validity period of the TRS availability indication can be appropriately controlled.

[0081] Fig. 6 is a diagram showing another example of TRS-related operations at the time of cell reselection according to the present embodiment. For example, in cells #4 and #5 in Fig. 6, it is assumed that cell-specific SIBx is broadcast. In Fig. 6, terminal 10 camps on cell #4 and receives cell #4-specific SIBx from base station 20 that forms cell #4. Terminal 10 may set TRS resources / opportunities based on TRS resource / opportunity information included in the SIBx.

[0082] Also, the terminal 10 camped on the cell #4 receives a TRS availability indication. The TRS availability indication may be included in any of the cell #4 specific SIBx, paging DCI, PEI DCI, TRS as PEI, or RRC message. The terminal 10 starts a validity timer for the TRS availability indication at timing T1. For example, in FIG. 6, the validity period is from timing T1 to T3.

[0083] In FIG. 6, the terminal 10 reselects a cell #5 different from the cell #4 at timing T2. The terminal 10 stops the validity timer at timing T2 without waiting for expiration at timing T3. The terminal 10 also receives a SIBx specific to the cell #5, and sets a TRS resource / opportunity based on the TRS resource / opportunity information in the SIBx. The terminal 10 camped on the cell #5 may receive a TRS availability indication, and start the validity timer of the TRS availability indication at timing T2. The validity timer expires at timing T4, and the validity period of the TRS availability indication received in the cell #5 ends.

[0084] As described above, the terminal 10 controls the validity timer of the TRS availability indication based on whether the SIBx including the TRS resource / opportunity information is area-specific. Therefore, even if the terminal 10 moves between cells, the validity period of the TRS availability indication can be appropriately controlled.

[0085] (2) TRS-related operations while a valid timer is running Next, the operation of the terminal 10 in the case where the transmission of the TRS is stopped while the validity timer is running will be described. The terminal 10 may use the validity timer to control the validity period of the TRS availability indication. For example, the terminal 10 may determine that the TRS availability indication is valid during the period from when the validity timer is started until it expires or is stopped (i.e., while the validity timer is running). Even while such a validity timer is running, an operation in which the transmission of the TRS is stopped for reasons such as the absence of a terminal in a connected state in the cell is also assumed.

[0086] 7(A) and (B) are diagrams showing an example of TRS operation during the validity timer according to the present embodiment. In FIG. 7(A) and (B), the TRS availability indication is included in the paging DCI, but is not limited thereto, and may be signaled to the terminal 10 using higher layer signaling such as system information or an RRC message, or physical layer signaling such as a PEI DCI or a specific signal for the PEI. In addition, the start timing of the validity timer is of course not limited to that shown in the figure.

[0087] FIG. 7(A) shows an example in which a validity timer started at timing T1 expires at timing T2. As shown in FIG. 7(A), the terminal 10 detects a paging DCI including a TRS availability indication (first indication information) indicating that the TRS is available in a PDCCH monitoring opportunity in PO#0. The terminal 10 may start a validity timer in response to the detection of the TRS availability indication, and determine that the period until the validity timer expires is the validity period of the TRS availability indication. The terminal 10 determines that the TRS is available in the TRS resource / opportunity within the validity period based on the TRS availability indication.

[0088] Furthermore, the terminal 10 detects a paging DCI indicating that the TRS is not available in the PDCCH monitoring opportunity in PO#4 after the validity timer expires. The terminal 10 determines that the TRS is not available in the TRS resource / opportunity based on the paging DCI.

[0089] In Fig. 7(B), an example is shown in which the validity timer started at timing T1 stops at timing T1'. As shown in Fig. 7(B), the terminal 10 differs from Fig. 7(A) in that it receives a TRS availability indication (second indication information) indicating that the TRS is not available at timing T1' while the validity timer is running. Fig. 7(B) will be described focusing on the differences from Fig. 7(A).

[0090] The terminal 10 detects a paging DCI including a TRS availability indication indicating that the TRS is not available during a PDCCH monitoring opportunity in PO#2 during which the validity timer is running. The terminal 10 stops the validity timer in response to the detection of the TRS availability indication. The terminal 10 determines that the TRS is not available in the TRS resource / opportunity after the timer is stopped. In this way, when the terminal 10 stops the validity timer at timing T1', the terminal 10 may determine that the validity period of the TRS availability indication detected in PO#0 has ended without waiting for the validity timer to expire.

[0091] In addition, the TRS availability indication indicating that the TRS notified while the validity timer is running is not available may be a specific value of at least some of the bits of the reserved field of the paging DCI (for example, the value "00" of 2 bits out of 6 bits).

[0092] As described above, when a TRS availability indication indicating that the TRS is unavailable is received while a validity timer for the validity period of a TRS availability indication indicating that the TRS is available is running, the terminal 10 may stop the validity timer and assume that the TRS is unavailable in the subsequent TRS resource / opportunity. This allows the terminal 10 to operate appropriately even when the system side changes whether or not to transmit the TRS.

[0093] (3) TRS-related operations based on SIBx Next, the operation of the terminal 10 when instructing the availability of TRS using SIBx will be described. Specifically, (3.1) Operation of changing the instruction regarding the availability of TRS using SIBx, and (3.2) Operation of controlling the validity period of the instruction regarding the availability of TRS using SIBx will be described.

[0094] (3.1) Change of TRS availability indication using SIBx As described in FIG. 2, in general, when the content of SIBx is changed, the terminal 10 detects notification information regarding the change of the SIBx (hereinafter, referred to as "SI change notification") in a certain update period, and acquires an SI message including the changed SIBx in the next update period. The SI change notification is also called "SI change indication" or the like. For the SI change notification, for example, a short message in a paging DCI may be used. The paging DCI may be monitored in each PO in the certain update period.

[0095] The terminal 10 may receive an SI message including an updated SIBx in the next update period based on an SI change notification detected in the previous update period. The update period may be composed of, for example, a predetermined number of radio frames. The boundary of the update period may be determined based on, for example, the SFN and the number of radio frames constituting the update period.

[0096] Incidentally, it is desirable to be able to change whether or not a TRS is actually transmitted in a TRS resource / opportunity depending on various factors. For example, when the traffic of the entire system increases, it is expected that overhead due to TRS will be reduced by not actually transmitting a TRS in the set TRS resource / opportunity. On the other hand, when the traffic of the entire system decreases, it is expected that the effect of reducing power consumption of terminal 10 will be enhanced by actually transmitting a TRS in the set TRS resource / opportunity.

[0097] In this way, when there is a change in whether or not a TRS is actually transmitted in a TRS resource / opportunity, a problem arises as to how to notify the change to the terminal 10. Here, when the terminal 10 determines whether or not a TRS is actually transmitted in a TRS resource / opportunity based on a TRS availability indication in the SIBx, it is assumed that an SI message update procedure (hereinafter, referred to as an "SI update procedure") is used.

[0098] However, the SI update procedure does not assume that the value of the TRS availability indication in the SIBx (or whether the SIBx contains a TRS availability indication or not) is changed, so there is a risk that the timing at which the TRS availability indication becomes effective and / or the validity period of the TRS availability indication cannot be appropriately controlled by using only the SI update procedure.

[0099] Therefore, when the TRS availability indication in the SIBx modified by the SI update procedure indicates that the TRS will actually be transmitted on the TRS resource / opportunity, the terminal 10 may determine the timing at which the TRS availability indication becomes effective (i.e., the start timing of the effective timer) based on a reference timing (hereinafter referred to as "reference timing").

[0100] The reference timing may be, for example, a timing related to reception of an SIBx including a TRS availability indication indicating that the TRS is available, a timing related to reception of an SIBx or SIB1 other than the SIBx, or a boundary of an update period. The timing related to reception may be a start or end timing of a received radio frame, slot, or symbol, or a start or end timing of a period (e.g., an SI window) used for reception.

[0101] Furthermore, the terminal 10 may determine the start timing of the valid timer based on the reference timing and an offset with respect to the reference timing. The offset may be specified by the number of slots, the number of radio frames, the number of hyper radio frames, time (e.g., milliseconds), an integer multiple of a paging cycle, or an integer multiple of a DRX period. The offset may be determined in advance in a specification, or may be notified by the base station 20. Furthermore, the value of the offset may be 0, and the terminal 10 may determine the reference timing as the timing at which the TRS availability indication becomes valid.

[0102] Furthermore, the terminal 10 may receive information related to the offset (hereinafter, referred to as "offset information") from the base station 20. The offset information may be included in the SIBx including the TRS availability indication, or may be included in another SIBx, or may be included in the SIB1, or may be included in another RRC message.

[0103] Fig. 8 is a diagram showing an example of an SI update procedure according to the present embodiment. For example, in Fig. 8, the TRS availability indication in the SIBx indicates that the TRS is actually transmitted in the TRS resource / opportunity, and if the TRS is not actually transmitted, the SIBx does not include the TRS availability indication. However, as described above, the TRS availability indication indicating whether the TRS is actually transmitted in the TRS resource / opportunity may be included in the SIBx.

[0104] For example, in FIG. 8, the SIBx transmitted in the previous update period does not include a TRS availability indication, indicating that the TRS is not actually transmitted in the TRS resource / opportunity. On the other hand, when a cause for the TRS to be actually transmitted is detected in the previous update period, the base station 20 transmits an SI change notification of an SI message including the SIBx in the PO. When the terminal 10 detects the SI change notification by PDCCH monitoring in the PO, the terminal 10 receives SIB1 in the next update period and receives an SI message including the changed SIBx based on the SIB1. Although not shown, the terminal 10 may receive an MIB before the post-boundary SIB1.

[0105] Also, the version information of SIBx in SIB1 in Fig. 8 (e.g., RRC IE "valueTag") indicates v1, which is incremented by 1 from v0. Since the version information of SIBx in SIB1 (here, v1) does not match the version information of SIBx stored in terminal 10 (here, v0), terminal 10 may obtain an SI message including SIBx of v1. Terminal 10 determines that a TRS is actually transmitted on a TRS resource / opportunity based on the TRS availability indication in SIBx of v1.

[0106] Also, in Fig. 8, the terminal 10 may determine the timing at which the TRS availability indication becomes valid based on the reference timing and an offset, with the boundary of the update period as the reference timing. The terminal 10 may start a validity timer at the determined timing. The terminal 10 may determine the period from when the validity timer is started to when the validity timer expires as the validity period of the TRS availability indication. The validity period may be specified as an integer multiple of the update period.

[0107] As shown in FIG. 8, when the validity timer expires, the base station 20 stops transmitting the TRS in the TRS resource / opportunity. The base station 20 may also stop broadcasting the SIBx of v1. Even if the base station 20 stops transmitting the TRS after the validity timer expires, it may not transmit an SI change notification. That is, the base station 20 does not need to broadcast the SIBx of v2 indicating that the TRS will not be transmitted after the validity timer expires. Also, the version information of the SIBx in the SIB1 may not be updated, and v1 may be maintained.

[0108] In Figure 8, the boundary of the update period is used as the reference timing, but as described above, the reference timing may be the timing related to the reception of an SI message including an SIBx of v1 containing a TRS availability indication, the timing related to the SI window in which the SI message is transmitted, or the timing related to the reception of SIB1, etc.

[0109] As described above, even if the TRS availability indication in the SIBx changed by the SI update procedure indicates that the TRS will actually be transmitted on the TRS resource / opportunity, the start timing of the validity timer and / or the validity period of the TRS availability indication can be appropriately controlled.

[0110] (3.2) Control of validity period using SIBx Incidentally, it is assumed that while a terminal 10 camping on a certain cell is activating the validity timer based on SIBx, another terminal 10 starts camping on the certain cell. In this case, when the validity timer expires, the base station 20 does not actually transmit a TRS in the TRS resource / opportunity, so that the expiration timing of the validity timer (i.e., the end timing of the validity period of the TRS availability indication in SIBx) needs to be consistent between terminals 10 belonging to the same cell.

[0111] Therefore, when base station 20 broadcasts information on the validity period of the TRS availability indication (hereinafter, "validity period information"), it generates the validity period information based on the elapsed time since the active validity timer started. The validity period information may be included in SIBx including the TRS availability indication, or may be included in another SIB (e.g., another SIBx or SIB1, etc.). For example, the validity period information may indicate how long the TRS availability indication is valid. Note that the elapsed time since the active validity timer started may be rephrased as the remaining time until the validity timer expires.

[0112] The validity period information may indicate, for example, the remaining time until the expiration timing of the validity timer, and the remaining time may be updated based on the elapsed time from the start timing of the validity period. Alternatively, the validity period information may indicate, for example, the time of expiration of the validity timer, a radio frame number, or a hyper radio frame number. That is, the validity period information may indicate the expiration timing of the validity timer in an absolute sense. For example, the validity period information may be specified using UTC (Universal Time Coordinated) time, and may indicate when the TRS availability indication (e.g., the content of the TRS availability indication) will expire.

[0113] Fig. 9 is a diagram showing an example of the control operation of the validity period of the TRS availability indication according to the present embodiment. For example, in Fig. 9, it is assumed that the terminal 10A is camped on a certain cell, and the validity timer indicating the validity period of the TRS availability indication in the SIBx is running. Note that in Fig. 9, the start timing of the activation of the validity timer is equal to the end timing of the reception of the SIBx, but this is merely an example and is not limited to this. As described above, the start timing may be determined based on the reference timing and the offset.

[0114] For example, in FIG. 9, the validity period information in the SIBx indicates the remaining time until the validity timer expires. As shown in FIG. 9, when the SIBx is broadcast at a predetermined cycle, the remaining time indicated by the validity period information included in each SIBx may be determined based on the elapsed time since the validity timer was started from the initial value. For example, the validity period information in the SIBx received while the validity timer is not running indicates the initial value of 10 seconds. On the other hand, the validity period information in the SIBx received while the validity timer is running may indicate the remaining time of 3 seconds based on the elapsed time from the initial value of 10 seconds.

[0115] In this way, the value indicated by the validity period information in the SIBx may be updated based on the elapsed time from the start timing of the validity timer. This makes it possible to avoid a mismatch in the expiration timing of the validity timer between the terminals 10A and 10B even when the terminal 10B camps on the same cell as the terminal 10A while the validity timer in the terminal 10A is running.

[0116] As shown in Fig. 9, the remaining time indicated by the validity period information in SIBx may be updated every SIBx period. The base station 20 may not transmit the above SI change notification even if the validity period information in SIBx is updated. On the other hand, when extending the initial value indicated by the validity period information in SIBx (10 seconds in Fig. 9), the base station 20 may perform an SI update procedure based on the above SI change notification and broadcast the SIBx of v2 including the validity period information indicating the extended initial value.

[0117] Fig. 10 is a diagram showing another example of the control operation of the validity period of the TRS availability indication according to the present embodiment. For example, in Fig. 10, the validity period information indicates SFN#128 as the expiration timing of the validity period. Note that the other operations in Fig. 10 are as described in Fig. 9.

[0118] In this way, the validity period information in the SIBx indicates the time at which the validity period expires or an index in time units, so that it is not necessary to update it sequentially based on the elapsed time from the start timing of the validity timer. Therefore, even if the update operation of the validity period information in the base station 20 described in FIG. 9 is not performed, it is possible to avoid discrepancies in the expiration timing of the validity timers between the terminals 10.

[0119] (Configuration of wireless communication system) Next, a description will be given of the configuration of each device of the above-described wireless communication system 1. Note that the following configuration is intended to show the configuration required in the description of this embodiment, and does not exclude each device from having a functional block other than that shown in the figure.

[0120] <Hardware configuration> 11 is a diagram showing an example of a hardware configuration of each device in the wireless communication system according to the present embodiment. Each device (e.g., a terminal 10, a base station 20, a CN 30, etc.) in the wireless communication system 1 includes a processor 11, a storage device 12, a communication device 13 that performs wired or wireless communication, and an input device that accepts various input operations and an input / output device 14 that outputs various information.

[0121] The processor 11 is, for example, a CPU (Central Processing Unit) and controls each device in the wireless communication system 1. The processor 11 may execute various processes described in the present embodiment by reading and executing a program from the storage device 12. Each device in the wireless communication system 1 may be configured with one or more processors 11. Furthermore, each of the devices may be called a computer.

[0122] The storage device 12 is configured with, for example, storage such as a memory, a hard disk drive (HDD) and / or a solid state drive (SSD), etc. The storage device 12 may store various information necessary for the processor 11 to execute processing (for example, a program executed by the processor 11, etc.).

[0123] The communication device 13 is a device that communicates via a wired and / or wireless network, and may include, for example, a network card, a communication module, a chip, an antenna, etc. The communication device 13 may also include an amplifier, an RF (Radio Frequency) device that performs processing related to wireless signals, and a BB (BaseBand) device that performs baseband signal processing.

[0124] The RF device performs, for example, D / A conversion, modulation, frequency conversion, power amplification, etc. on the digital baseband signal received from the BB device to generate a radio signal to be transmitted from the antenna A. The RF device also performs frequency conversion, demodulation, A / D conversion, etc. on the radio signal received from the antenna to generate a digital baseband signal and transmit it to the BB device. The BB device performs a process of converting the digital baseband signal into a packet, and a process of converting the packet into a digital baseband signal.

[0125] The input / output device 14 includes, for example, input devices such as a keyboard, a touch panel, a mouse, and / or a microphone, and output devices such as a display and / or a speaker.

[0126] The hardware configuration described above is merely an example. Each device in the wireless communication system 1 may omit some of the hardware shown in Fig. 11, or may include hardware not shown in Fig. 11. Furthermore, the hardware shown in Fig. 11 may be configured by one or more chips.

[0127] <Function block configuration> <Device> 12 is a diagram showing an example of a functional block configuration of a terminal according to this embodiment. As shown in FIG. 12, the terminal 10 includes a receiving unit 101, a transmitting unit 102, and a control unit 103.

[0128] All or part of the functions realized by the receiving unit 101 and the transmitting unit 102 can be realized by using the communication device 13. All or part of the functions realized by the receiving unit 101 and the transmitting unit 102 and the control unit 103 can be realized by the processor 11 executing a program stored in the storage device 12. The program can be stored in a storage medium. The storage medium storing the program may be a non-transitory computer readable medium. The non-transitory storage medium is not particularly limited, and may be, for example, a storage medium such as a USB memory or a CD-ROM.

[0129] The receiving unit 101 receives a downlink signal. The receiving unit 101 may also receive information and / or data transmitted via the downlink signal. Here, "receive" may include performing at least one of reception-related processes such as reception, demapping, demodulation, decoding, monitoring, and measurement of a radio signal. The downlink signal may include at least one of a PDSCH, a PDCCH, a downlink reference signal, a synchronization signal, a PBCH, and the like.

[0130] The receiver 101 monitors PDCCH candidates in a search space to detect DCI. The receiver 101 may receive downlink user data and / or higher layer control information (e.g., Medium Access Control Element (MAC CE), an RRC message, or a NAS message) via a PDSCH scheduled using DCI.

[0131] Specifically, the receiving unit 101 receives SIBx (system information). The receiving unit 101 may also receive indication information indicating that TRS is available in a TRS resource / period (resource and / or period) (for example, see (1) and (2) above). The indication information may be included in the SIBx, paging DCI, or PEI DCI.

[0132] Furthermore, while the validity timer is running, the receiving unit 101 may receive an indication (second indication) indicating that the TRS is available in the TRS resource / opportunity (for example, see (2) above). The indication may be included in the paging DCI, or may be a specific value of at least some bits of the reserved field of the paging DCI.

[0133] The receiving unit 101 may also receive an SIBx including indication information indicating that a TRS is available in a TRS resource / opportunity (for example, see (3) above). The receiving unit 101 may receive the SIBx in the next update period based on an SI change notification (system information change notification) detected in the previous update period (for example, see FIG. 8). The receiving unit 101 may also receive offset information for a reference timing.

[0134] Furthermore, the receiving unit 101 may receive validity period information regarding the validity period of the indication information indicating that the TRS is available in the TRS resource / opportunity. The validity period information indicates the remaining time until the expiration timing of the validity timer, and the remaining time may be updated based on the elapsed time from the start timing of the validity period (e.g., FIG. 9). Alternatively, the validity period information may indicate the time of expiration timing, the radio frame number, or the hyper radio frame number (e.g., FIG. 10).

[0135] The transmitting unit 102 transmits an uplink signal. The transmitting unit 102 may also transmit information and / or data transmitted via the uplink signal. Here, "transmitting" may include performing processing related to transmission, such as at least one of encoding, modulation, mapping, and transmission of a radio signal. The uplink signal may include at least one of an uplink shared channel (e.g., a Physical Uplink Shared channel (PUSCH)), a random access preamble (e.g., a Physical Random Access Channel (PRACH)), an uplink reference signal, etc.

[0136] The transmitting unit 102 may transmit uplink user data and / or higher layer control information (for example, MAC CE, RRC message, etc.) via a PUSCH scheduled using the DCI received by the receiving unit 101.

[0137] The control unit 103 performs various controls in the terminal 10 .

[0138] For example, the control unit 103 may set the TRS resource / opportunity based on SIBx or an RRC message.

[0139] Furthermore, when reselecting a cell to camp on, the control unit 103 may control a validity timer related to the validity period of the TRS availability indication based on whether or not the SIBx is area-specific (for example, see (1) above, FIGS. 5 and 6). Specifically, when the SIBx is area-specific, if cell reselection is performed between cells belonging to the same area while the validity timer is running, the control unit 103 may continue the validity timer. When the SIBx is area-specific, if cell reselection is performed between cells belonging to different areas while the validity timer is running, the control unit 103 may stop the validity timer. When the SIBx is not area-specific, if cell reselection is performed between cells while the validity timer is running, the control unit 103 may stop the validity timer.

[0140] Furthermore, the control unit 103 controls a validity timer related to the validity period of the TRS availability indication. Specifically, the control unit 103 starts a timer related to the validity period of the first indication information indicating that the TRS is available in the TRS resource / opportunity (for example, see (2) above, FIG. 7(A)). Furthermore, the control unit 103 may stop the validity timer when the receiving unit 101 receives second indication information indicating that the TRS is not available in the TRS resource / opportunity while the validity timer is running (for example, see (2) above, FIG. 7(B)).

[0141] Specifically, when a DCI (e.g., a paging DCI) CRC-scrambled by a specific RNTI is detected in a PDCCH monitoring opportunity in a PO, the control unit 103 may stop the validity timer based on the second instruction information in the DCI (e.g., see FIG. 7(B)). Also, the control unit 103 may determine that a TRS is not transmitted in a TRS resource / opportunity after a predetermined timing after the validity timer is stopped (e.g., see FIG. 7(B)).

[0142] Furthermore, the control unit 103 may determine the start timing of the valid timer using a timing related to reception of SIBx, a timing related to reception of system information other than the system information, or a boundary of an update period as a reference timing (for example, see (3) above and FIG. 8). The control unit 103 may determine the start timing of the valid timer based on the reference timing and an offset indicated by the offset information. The control unit 103 may also determine the expiration timing of the valid timer based on the validity period information.

[0143] ≪Base station≫ 13 is a diagram showing an example of a functional block configuration of a base station according to this embodiment. As shown in FIG. 13, the base station 20 includes a receiving unit 201, a transmitting unit 202, and a control unit 203.

[0144] All or part of the functions realized by the receiving unit 201 and the transmitting unit 202 can be realized by using the communication device 13. All or part of the functions realized by the receiving unit 201 and the transmitting unit 202 and the control unit 203 can be realized by the processor 11 executing a program stored in the storage device 12. The program can be stored in a storage medium. The storage medium storing the program may be a computer-readable non-transitory storage medium. The non-transitory storage medium is not particularly limited, and may be, for example, a storage medium such as a USB memory or a CD-ROM.

[0145] The receiving unit 201 receives the upstream signal. The receiving unit 201 may also receive information and / or data transmitted via the upstream signal.

[0146] The transmitting unit 202 transmits the downlink signal. The transmitting unit 202 may also transmit information and / or data transmitted via the downlink signal. Specifically, the transmitting unit 202 transmits SIBx (system information). The transmitting unit 202 may also transmit indication information indicating that the TRS is available in a TRS resource / period (resource and / or period).

[0147] In addition, while the validity timer is running, the transmitting unit 202 may transmit indication information (second indication information) indicating that the TRS is available in the TRS resource / opportunity (for example, see (2) above).

[0148] Furthermore, the transmitting unit 202 may transmit an SIBx including indication information indicating that a TRS is available in a TRS resource / opportunity (see, for example, (3) above). The transmitting unit 202 may transmit the SIBx in the next update period based on an SI change notification (system information change notification) detected in the previous update period (see, for example, FIG. 8). The transmitting unit 202 may also transmit offset information for the reference timing. The transmitting unit 202 may also transmit validity period information regarding the validity period.

[0149] The control unit 203 performs various controls in the base station 20. For example, the control unit 203 may control whether or not to transmit a TRS in a TRS resource / opportunity based on various factors. Note that some information transmitted from the transmission unit 202 of the base station may be transmitted by a transmission unit in a device on the core network 30.

[0150] (supplement) Various signals, information, and parameters in the above embodiments may be signaled in any layer. That is, the above various signals, information, and parameters may be replaced with signals, information, and parameters of any layer, such as an upper layer (e.g., a Non Access Stratum (NAS) layer, an RRC layer, a MAC layer, etc.) or a lower layer (e.g., a physical layer). In addition, notification of predetermined information is not limited to being explicitly performed, and may be performed implicitly (e.g., by not notifying information or by using other information).

[0151] Furthermore, the names of various signals, information, parameters, IEs, channels, time units, and frequency units in the above embodiments are merely examples and may be replaced with other names. For example, a slot may be named in any way as long as it is a time unit having a predetermined number of symbols. Furthermore, an RB may be named in any way as long as it is a frequency unit having a predetermined number of subcarriers. Furthermore, "first..." and "second..." are merely identifiers of multiple pieces of information or signals, and the order may be changed as appropriate.

[0152] In addition, the applications of the terminal 10 in the above embodiments (e.g., RedCap, IoT, etc.) are not limited to those exemplified, and as long as it has similar functions, it may be used for any application (e.g., eMBB, URLLC, Device-to-Device (D2D), Vehicle-to-Everything (V2X), etc.). In addition, the format of various information is not limited to the above embodiments, and may be changed as appropriate to bit representation (0 or 1), boolean value (Boolean: true or false), integer value, character, etc. In addition, singular and plural in the above embodiments may be changed mutually.

[0153] The above-described embodiments are intended to facilitate understanding of the present disclosure, and are not intended to limit the present disclosure. The flowcharts, sequences, elements included in the embodiments, and their arrangements, indexes, conditions, etc. described in the embodiments are not limited to those exemplified, and can be changed as appropriate. In addition, at least some of the configurations described in the above embodiments can be partially replaced or combined. [Explanation of symbols]

[0154] 1... wireless communication system, 20... base station, 30... core network, 101... receiving unit, 102... transmitting unit, 103... control unit, 201... receiving unit, 202... transmitting unit, 203... control unit, 11... processor, 12... storage device, 13... communication device, 14... input / output device

Claims

1. A method for receiving system information including information indicating resources for a tracking reference signal (TRS) and information indicating a validity period for information indicating availability of the TRS, A receiver that receives downlink control information including information regarding availability of the TRS via a physical downlink control channel; A control unit that controls a validity period for information indicating availability of the TRS based on the information indicating the validity period in an idle state or an inactive state; The receiving unit receives the system information broadcast in a reselected cell when reselection of a cell to camp on is performed, The control unit controls a validity period for information indicating availability of the TRS based on information indicating the validity period included in the system information broadcast in the reselected cell. Terminal.

2. The control unit discards the validity period based on the fact that a reselection of a cell to camp on is performed. The terminal according to claim 1.

3. The control unit: When the system information is specific to an area including a plurality of cells, and reselection of a cell to camp on is performed among a plurality of cells in the same area, the validity period is not discarded; discarding the validity period if the system information is specific to an area including a plurality of cells and a reselection of a cell to camp on is performed among a plurality of cells in a different area; The terminal according to claim 1.

4. The system information is specific to a cell; The control unit stops the validity period of the information indicating the availability of the TRS when reselection of a cell to camp on is performed. A terminal according to any one of claims 1 to 3.

5. The control unit controls the validity period based on information indicating a resource for the TRS and information indicating the validity period; The downlink control information includes a field used for a pre-paging indication (PEI) or has a cyclic redundancy check (CRC) scrambled by the P-RNTI added thereto. A terminal according to any one of claims 1 to 4.

6. Transmitting system information including information indicating resources for a tracking reference signal (TRS) and information indicating a validity period for information indicating availability of the TRS; A transmitter that transmits downlink control information including information regarding availability of the TRS on a physical downlink control channel; A control unit that controls a validity period for information indicating availability of the TRS for a terminal in an idle state or an inactive state based on the information indicating the validity period; The validity period for the information indicating the availability of the TRS is controlled based on information indicating the validity period included in the system information broadcast in the reselected cell when the terminal reselects the cell to which it camps. Base station.

7. The validity period is discarded based on the terminal performing a reselection of a cell on which to camp. The base station according to claim 6.

8. The validity period is not discarded when the system information is specific to an area including a plurality of cells and the terminal performs reselection of a cell to camp on among a plurality of cells in the same area, The validity period is discarded when the system information is specific to an area including a plurality of cells, and the terminal performs reselection of a cell to camp on among a plurality of cells in a different area. The base station according to claim 6.

9. The system information is cell-specific; The validity period of the information indicating the availability of the TRS is suspended when the terminal reselects a cell to camp on. A base station according to any one of claims 6 to 8.

10. The validity period is controlled based on information indicating a resource for the TRS and information indicating the validity period; The downlink control information includes a field used for a pre-paging indication (PEI) or has a cyclic redundancy check (CRC) scrambled by the P-RNTI added thereto. A base station according to any one of claims 6 to 9.

11. A method for receiving system information including information indicating resources for a tracking reference signal (TRS) and information indicating a validity period for information indicating availability of the TRS; receiving downlink control information including information regarding availability of the TRS on a physical downlink control channel; and controlling, in an idle state or an inactive state, a validity period for information indicating availability of the TRS based on the information indicating the validity period; The receiving step includes receiving the system information broadcast in a reselected cell when a reselection of a cell to camp on is performed; The controlling step controls a validity period for the information indicating the availability of the TRS based on information indicating the validity period included in the system information broadcast in the reselected cell. The terminal's wireless communication method.

12. The step of controlling discards the validity period based on a reselection of a cell to camp on. The wireless communication method according to claim 11.

13. The controlling step comprises: When the system information is specific to an area including a plurality of cells, and reselection of a cell to camp on is performed among a plurality of cells in the same area, the validity period is not discarded; discarding the validity period if the system information is specific to an area including a plurality of cells and a reselection of a cell to camp on is performed among a plurality of cells in a different area; The wireless communication method according to claim 11.

14. The system information is cell specific; The step of controlling includes suspending the validity period of the information indicating the availability of the TRS when a reselection of a cell to camp on is performed. A wireless communication method according to any one of claims 11 to 13.

15. The step of controlling includes controlling the validity period based on information indicating a resource for the TRS and information indicating the validity period; The downlink control information includes a field used for a pre-paging indication (PEI) or has a cyclic redundancy check (CRC) scrambled by the P-RNTI added thereto. A wireless communication method according to any one of claims 11 to 14.

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