Communication device, base station, and communication method

Abstract

A communication device (100) according to an embodiment comprises: a reception unit (111) that uses system information to receive, from a base station (200), a random access configuration including first configuration information including information indicating a first PRACH resource, and that receives DCI from the base station; and a control unit (120). The control unit (120) determines, on the basis of second configuration information including information indicating a second PRACH resource which is included in the random access configuration, that the DCI includes a bit indicating the availability of the second PRACH resource indicated by the information indicating the second PRACH resource, and determines, on the basis of the value of the bit indicating the availability of the second PRACH resource, whether the second PRACH resource is available.

Description

Communication Device, Base Station, and Communication Method Cross - Reference to Related Applications

[0001] This application is based on Patent Application No. 2024 - 174507 filed on October 3, 2024, claims the benefit of its priority, and all the contents of that patent application are incorporated herein by reference.

[0002] This disclosure relates to a communication device, a base station, and a communication method.

[0003] In the 3GPP (Registered Trademark. The same shall apply hereinafter) (Third Generation Partnership Project), which is a standardization project for mobile communication systems, network energy saving (NES) is being discussed. As one of the NES, the introduction of time - domain PRACH adaptation (hereinafter referred to as PRACH adaptation) that enables the addition of PRACH resources separately from existing physical random access channel (PRACH) resources has been considered (see, for example, Non - Patent Document 1).

[0004] In PRACH adaptation, it is assumed that downlink control information (DCI) indicates whether additional PRACH resources are available. By increasing the period of existing PRACH resources while making additional PRACH resources available by DCI as needed, it is possible to achieve flexible PDCCH transmission while saving network energy.

[0005] “R1 - 2407039” (Adaptation of common channel transmissions)

[0006] The communication device according to the first embodiment includes a receiving unit (111) that receives a random access setting from a base station using system information, which includes first setting information including information indicating a first physical random access channel (PRACH) resource, and a control unit (120) that receives downlink control information (DCI) from the base station. The control unit determines, based on the second setting information which includes information indicating a second PRACH resource included in the random access setting, that the DCI includes a bit indicating the availability of the second PRACH resource as indicated by the information indicating the second PRACH resource, and determines whether the second PRACH resource is available or not based on the value of the bit indicating the availability of the second PRACH resource.

[0007] A base station according to the second embodiment includes a transmitting unit that transmits a random access setting to a communication device using system information, the setting including first setting information which includes information indicating a first physical random access channel (PRACH) resource. The transmitting unit transmits downlink control information (DCI) to the communication device. The random access setting includes second setting information which includes information indicating a second PRACH resource. The second setting information is used by the communication device to determine that the DCI includes a bit indicating the availability of the second PRACH resource, as indicated by the information indicating the second PRACH resource. The value of the bit indicating the availability of the second PRACH resource is used by the communication device to determine whether the second PRACH resource is available or not.

[0008] The third aspect of the communication method is a communication method performed by a communication device. The communication method comprises the steps of: receiving a random access setting from a base station using system information, which includes a first setting information including information indicating a first physical random access channel (PRACH) resource; receiving downlink control information (DCI) from the base station; determining, based on the second setting information including information indicating a second PRACH resource included in the random access setting, that the DCI includes a bit indicating the availability of the second PRACH resource as indicated by the information indicating the second PRACH resource; and determining, based on the value of the bit indicating the availability of the second PRACH resource, whether or not the second PRACH resource is available.

[0009] The fourth aspect of the communication method is a communication method performed at a base station. The communication method comprises the steps of: transmitting a random access setting, which includes first setting information including information indicating a first physical random access channel (PRACH) resource, to a communication device using system information; and transmitting downlink control information (DCI) to the communication device. The random access setting includes second setting information including information indicating a second PRACH resource. The second setting information is used by the communication device to determine that the DCI includes a bit indicating the availability of the second PRACH resource, as indicated by the information indicating the second PRACH resource. The value of the bit indicating the availability of the second PRACH resource is used by the communication device to determine whether the second PRACH resource is available or not.

[0010] The purpose, features, and advantages of this disclosure will become clearer with reference to the attached drawings and the detailed description below. Figure 1 is a diagram showing the configuration of a mobile communication system according to an embodiment. Figure 2 is a diagram showing an example of the configuration of a protocol stack according to an embodiment. Figure 3 is a diagram showing the configuration of a UE according to an embodiment. Figure 4 is a diagram showing the configuration of a base station according to an embodiment. Figure 5 is a sequence diagram for illustrating an example of operation according to an embodiment. Figure 6 is a diagram for illustrating an example of operation according to an embodiment.

[0011] A mobile communication system according to an embodiment will be described with reference to the drawings. In the drawings, identical or similar parts are denoted by the same or similar reference numerals.

[0012] One of the objectives of this disclosure is to provide a communication device, base station, and communication method that enable proper PRACH adaptation.

[0013] (System Configuration) First, the configuration of the mobile communication system 1 according to this embodiment will be described with reference to Figure 1. The mobile communication system 1 is, for example, a system that conforms to the Technical Specifications (TS) of 3GPP. In the following, the mobile communication system 1 will be described using as an example the 5th Generation System (5G system) of the 3GPP standard, that is, a mobile communication system based on NR (New Radio).

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

[0015] UE100 is a communication device that communicates via base station 200. UE100 may be a device used by a user. UE100 may be a mobile device such as a smartphone or other mobile phone terminal, tablet terminal, notebook PC, communication module, or communication card. UE100 may be a vehicle (e.g., car, train, etc.) or a device installed thereon (e.g., Vehicle UE). UE100 may be a transport vehicle other than a vehicle (e.g., ship, airplane, etc.) or a device installed thereon (e.g., Aerial UE). UE100 may be a sensor or a device installed thereon. Note that UE100 may also be referred to by other names such as terminal, terminal device, mobile station, mobile terminal, mobile device, mobile unit, subscriber station, subscriber terminal, subscriber device, subscriber unit, wireless station, wireless terminal, wireless device, wireless unit, remote station, remote terminal, remote device, or remote unit. Furthermore, UE100 is just one example of a terminal, and terminals may include factory equipment, etc.

[0016] NG-RAN20 includes a plurality of base stations 200. Each base station 200 manages at least one cell. One or more base stations 200 may correspond to one or more cells. A base station 200 may be replaced by a cell, and a cell may be replaced by a base station 200. A cell constitutes the smallest unit of a communication area. One cell belongs to one frequency (carrier frequency). The term "cell" may represent a radio communication resource, or it may represent a communication target of UE100. Each base station 200 can perform radio communication with UE100 located within its own cell. Base stations 200 communicate with UE100 using the RAN protocol stack. Details of the protocol stack will be described later. Base stations 200 are also connected to other base stations 200 (which may be called adjacent base stations) via the Xn interface. Base stations 200 communicate with adjacent base stations via the Xn interface. Furthermore, the base station 200 provides NR user plane and control plane protocol termination for UE100 and is connected to 5GC30 via the NG interface. Such an NR base station 200 is sometimes referred to as gNodeB (gNB).

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

[0018] (Example of protocol stack configuration) Next, an example of the protocol stack configuration according to this embodiment will be described with reference to Figure 2.

[0019] The protocol for the radio section between UE100 and base station 200 comprises a physical (PHY) layer, a MAC (Medium Access Control) layer, an RLC (Radio Link Control) layer, a PDCP (Packet Data Convergence Protocol) layer, and an RRC (Radio Resource Control) layer.

[0020] The PHY layer performs encoding and decoding, modulation and demodulation, antenna mapping and demapping, and resource mapping and demapping. Data and control information are transmitted between the PHY layer of UE100 and the PHY layer of base station 200 via a physical channel.

[0021] The MAC layer performs data priority control, retransmission processing using Hybrid ARQ (HARQ), and random access procedures. Data and control information are transmitted between the MAC layer of UE100 and the MAC layer of base station 200 via the transport channel. The MAC layer of base station 200 includes a scheduler. The scheduler determines the transport format for the uplink and downlink (transport block size, modulation and coding scheme (MCS)) and the resources to be allocated to UE100.

[0022] The RLC layer transmits data to the receiving RLC layer using the functions of the MAC layer and PHY layer. Data and control information are transmitted between the RLC layer of UE100 and the RLC layer of base station 200 via a logical channel.

[0023] The PDCP layer performs header compression / decompression, encryption / decryption.

[0024] A Service Data Adaptation Protocol (SDAP) layer may be provided as a layer above the PDCP layer. The SDAP layer maps IP flows, which are the units in which the core network performs Quality of Service (QoS) control, to wireless bearers, which are the units in which the Access Stratum (AS) performs QoS control.

[0025] The RRC layer controls the logical channel, transport channel, and physical channel in response to the establishment, re-establishment, and release of the radio bearer. RRC signaling for various settings is transmitted between the RRC layer of UE100 and the RRC layer of base station 200. If there is an RRC connection between the RRC layer of UE100 and the RRC layer of base station 200, UE100 is in the RRC connected state. If there is no RRC connection between the RRC layer of UE100 and the RRC layer of base station 200, UE100 is in the RRC idle state. If the RRC connection between the RRC layer of UE100 and the RRC layer of base station 200 is suspended, UE100 is in the RRC inactive state.

[0026] In UE100, the NAS layer, located above the RRC layer, performs session management and mobility management for UE100. NAS signaling is transmitted between the NAS layer of UE100 and the NAS layer of the core network device 300.

[0027] Furthermore, the UE100 has an application layer and other components in addition to the wireless interface protocol.

[0028] (Wireless Frame Configuration) In a 5G system, downlink and uplink transmissions are composed within wireless frames with a duration of 10ms. For example, a wireless frame is represented by a System Frame Number (SFN) from 0 to 1023. For example, a wireless frame consists of 10 subframes. For example, one subframe may be 1ms long. Also, one subframe may consist of one or more slots. For example, the number of symbols that make up one slot is usually 14 for a Cyclic Prefix (CP) and 12 for an extended CP. Also, the number of slots that make up one subframe changes according to the set subcarrier interval. For example, for a normal CP, if the subcarrier interval is set to 15 kHz, the number of slots per subframe is 1 (i.e., 14 symbols); if the subcarrier interval is set to 30 kHz, the number of slots per subframe is 2 (i.e., 28 symbols); if the subcarrier interval is set to 60 kHz, the number of slots per subframe is 4 (i.e., 56 symbols); and if the subcarrier interval is set to 120 kHz, the number of slots per subframe is 8 (i.e., 112 symbols). Also, for an extended CP, if the subcarrier interval is set to 60 kHz, the number of slots per subframe is 4 (i.e., 48 symbols). In other words, the number of slots constituting one subframe is determined based on the subcarrier interval set by the base station 200. Also, the number of symbols constituting one subframe is determined based on the subcarrier interval set by the base station 200. In other words, the number of symbols constituting a 1 ms subframe is determined based on the subcarrier interval set by the base station 200, and the length (length in the time direction) of each symbol changes.

[0029] (Determination of PRACH transmission opportunity) The determination of a PRACH transmission opportunity will be explained. The UE100 determines a PRACH opportunity (or PRACH transmission opportunity) when, for example, executing a random access (RA) procedure.

[0030] UE100 may, for example, (a) initial access from an RRC idle state, (b) RRC connection re-establishment procedure, (c) arrival of downlink or uplink data during an RRC connected state when the uplink synchronization status is "asynchronous", (d) arrival of uplink data when there are no available physical uplink control channel (PUCCH) resources for a scheduling request (SR), (e) SR failure, (f) RRC request for synchronization re-establishment (e.g., handover), (g) RRC connection resume procedure from an RRC inactive state, (h) establish time adjustment for a secondary timing advance group (TAG), and (i) Other System Information The RA procedure may be executed if it is triggered by any of the following events: (j) a request for SI, (k) beam fault recovery, (l) a consistent uplink listen-before-talk (UL LBT) failure in an SpCell, (i) small data transmission (SDT) in an RRC inactive state, or (m) for positioning purposes in an RRC connected state that requires the RA procedure (e.g., when timing advance is required for UE positioning).

[0031] In the RA procedure, UE100 determines resources (i.e., PRACH opportunities) for PRACH transmission, for example, using a set of predefined random access configurations and random access (RA) parameters included in System Information Block Type 1 (SIB1).

[0032] Random access (RA) settings are defined by a table (RA setting table) that shows the PRACH preamble format, the allocation of time domains for PRACH opportunities, and their association with PRACH setting indexes. UE100 stores this table in advance.

[0033] RA parameters are specified by RACH configuration common information (e.g., RACH-ConfigCommon, RACH-ConfigCommonTwoStepRA) used to specify random access parameters. "RACH-ConfigCommon" may be information used to identify cell-specific random access parameters. "RACH-ConfigCommonTwoStepRA" may be information used to identify cell-specific two-step random access type parameters.

[0034] Common RACH configuration information may include, for example, a PRACH configuration index (e.g., prach-ConfigurationIndex, msgA-PRACH-ConfigurationIndex(-r16)), information on the number of PRACH transmission opportunities (e.g., msg1-FDM, msgA-RO-FDM(-r16)), etc. "msg1-FDM" may indicate the number of PRACH transmission opportunities that are FDM-converted in a single instance. "msgA-RO-FDM" may indicate the number of msgA PRACH transmission opportunities that are multi-frequency-divided (Frequency-Division Multiplexed) in a single instance. The PRACH setting index indicates which of the multiple RA settings defined in the RA setting table will be used for the PRACH opportunity during a PRACH transmission. UE100 determines the PRACH opportunity using the RA setting indicated by the PRACH setting index.

[0035] Furthermore, the UE100 maps the synchronization signal (SS) and the physical broadcast channel (PBCH) block (SSB) index (hereinafter sometimes referred to as the SSB index) to the PRACH opportunity.

[0036] The SSB index is mapped to active PRACH opportunities, for example, in the following order, using parameters provided by RACH configuration common information (e.g., ssb-perRACH-OccasionAndCB-PreamblesPerSSB included in RACH-ConfigCommon, and / or msgA-SSB-PerRACH-OccasionAndCB-PreamblesPerSSB included in RACH-ConfigCommonTwoStepRA) (e.g., the number of SSBs associated with one PRACH occasion, the number of contention-based preambles per SSB per active PRACH opportunity):

[0037] Firstly, ascending order of preamble index within a single PRACH opportunity. Secondly, ascending order of frequency resource index for frequency multiplexed PRACH opportunities. Thirdly, ascending order of time resources for time multiplexed PRACH opportunities within a PRACH slot. Fourthly, ascending order of index for PRACH slots.

[0038] The association period for when UE100 performs the mapping is defined. The association period is the minimum value within the set determined by the PRACH configuration period. The association period starts from frame 0. Within the association period, a predetermined number of SSB indexes are mapped to a PRACH opportunity at least once. UE100 obtains this predetermined number from information within SIB1 or within the ServingCell Configuration Common Information (e.g., ServingCellConfigCommon) (e.g., ssb-PositionsInBurst). In the set determined by the PRACH configuration period, the PRACH configuration period (ms) and the association period (number of PRACH configuration periods) are associated in the table.

[0039] If, within the association period, after an integer of the SSB index to the mapping cycle of PRACH opportunities, there is a predetermined number of sets of PRACH opportunities or PRACH preambles that are not mapped to an SSB index, the SSB index will not map to those sets of PRACH opportunities or PRACH preambles.

[0040] An association pattern period consists of one or more association periods. The association pattern period is determined so that the pattern between PRACH opportunities and SSB indices repeats every 160 msec. PRACH opportunities that are not associated with an SSB index after an integer association period are not used for PRACH transmissions.

[0041] (Assumed Scenario) In the 3GPP, a standardization project for mobile communication systems, Network Energy Saving (NES) is being discussed. As one aspect of NES, the introduction of time-domain PRACH adaptation (hereinafter referred to as PRACH adaptation), which allows for the addition of PRACH resources separate from existing physical random access channel (PRACH) resources, is being considered.

[0042] PRACH adaptation is expected to indicate whether additional PRACH resources are available via downlink control information (DCI). By extending the cycle of existing PRACH resources while making additional PRACH resources available as needed via DCI, it becomes possible to achieve flexible physical downlink control channel (PDCCH) transmission while saving network energy.

[0043] However, there are concerns that PRACH adaptation may not be performed properly because specific procedures for PRACH adaptation based on DCI are not defined. Therefore, the procedures necessary to enable proper PRACH adaptation will be described below.

[0044] (Configuration of User Equipment) Referring to FIG. 4, the configuration of UE 100 according to the embodiment will be described. UE 100 includes a communication unit 110 and a control unit 120.

[0045] The communication unit 110 performs wireless communication with the base station 200 by transmitting and receiving radio signals to and from the base station 200. The communication unit 110 has at least one transmitter 111 and at least one receiver 112. The transmitter 111 and the receiver 112 may be configured to include a plurality of antennas and RF (Radio Frequency) circuits. The antenna converts a signal into an electromagnetic wave and radiates the electromagnetic wave into space. Also, the antenna receives an electromagnetic wave in space and converts the electromagnetic 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.

[0046] The control unit 120 performs various controls in UE 100. The control unit 120 controls communication with the base station 200 via the communication unit 110. The operations of 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.

[0047] (Configuration of the Base Station) Referring to FIG. 5, 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.

[0048] The communication unit 210 receives, for example, a radio signal from the UE 100 and transmits a radio signal to the UE 100. The communication unit 210 includes at least one transmission unit 211 and at least one reception unit 212. The transmission unit 211 and the reception unit 212 may be configured to include an RF circuit. The RF circuit performs analog processing of signals transmitted and received via an antenna. The RF circuit may include a high-frequency filter, an amplifier, a modulator, a low-pass filter, and the like.

[0049] 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 an interface between base stations, 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.

[0050] The control unit 230 performs various controls on the base station 200. For example, the control unit 230 controls communication with the UE 100 via the communication unit 210. The control unit 230 also controls communication with nodes (e.g., adjacent 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 controlled by the control unit 230. The control unit 230 may include at least one processor capable of executing programs and a memory for storing programs. The processor may execute programs to perform the operations of the control unit 230. The control unit 230 may include a digital signal processor that performs digital processing of signals transmitted and received via the antenna and RF circuit. This digital processing includes processing of the RAN protocol stack. The memory stores programs executed by the processor, parameters related to the programs, and data related to the programs. All or part of the memory may be contained within the processor.

[0051] (Example of Operation) An example of operation will be explained with reference to Figures 5 and 6. Previously explained details may be omitted.

[0052] UE100 may be in an RRC idle state or an RRC inactive state with respect to the cell managed by base station 200. Alternatively, UE100 may be in an RRC connected state with respect to the cell. The cell may be the cell where UE100 is camping, or it may be the cell that UE100 has (re)selected. The cell may also be the cell with which UE100 has established an RRC connection. In this example, we will proceed with the explanation assuming that UE100 is in an RRC idle state.

[0053] Furthermore, for UE100, communication with base station 200 may also be communication with a cell. Therefore, for UE100, receiving information / messages from base station 200 may be receiving information / messages from a cell, and sending information / messages to base station 200 may be sending information / messages to a cell.

[0054] Step S101: The transmitter 211 of the base station 200 may transmit a radio resource control (RRC) message to the UE 100. The receiver 112 of the UE 100 receives the RRC message from the base station 200 (cell). The transmitter 211 of the base station 200 may transmit the RRC message by broadcast, or it may transmit the RRC message to the UE 100 individually.

[0055] An RRC message may contain system information including specific information as described below. An RRC message containing system information including specific information may be a system information block type 1 (SIB1) message, or a system information message used to carry one or more system information blocks. An SIB1 message may contain information relevant when UE 100 evaluates whether access to a cell is permitted. A system information message may contain a specific system information block including specific information. An RRC message containing system information may be transmitted by broadcast. In addition, RRC messages transmitted individually to UE 100 may be, for example, an RRC release message used to command the release or suspension of an RRC connection, or an RRC reset message which is a command to change an RRC connection.

[0056] The control unit 230 of the base station 200 may control whether or not to include specific information in the RRC message. The control unit 230 may include specific information in the RRC message when setting up (for example, applying, allowing) a PRACH adaptation for the UE 100.

[0057] Identifying information is information used to determine whether the DCI contains the fields described below (specifically, the PRACH availability indicator field (hereinafter referred to as the PRACH availability field)). Identifying information may also be information used to determine whether the PRACH availability field exists in the DCI. Identifying information may include at least one of the following pieces of information.

[0058] Firstly, the specific information may include configuration information for setting up the second PRACH resource described below (hereinafter referred to as the second PRACH configuration information). The second PRACH configuration information may include, for example, information for setting parameters for the second PRACH resource. The second PRACH configuration information may include information indicating the second PRACH resource. The second PRACH configuration information may include information for monitoring the DCI including the PRACH availability field (for example, search space and / or CORESET information). The second PRACH configuration information may also be referred to as the PRACH adaptation resource set configuration.

[0059] Here, the second PRACH resource is a PRACH resource that can be added separately from the first PRACH resource. The first PRACH resource may be an (existing) PRACH resource configured for a legacy UE. The first PRACH resource may also be configured for a UE that supports NES (hereinafter, NES UE). The first PRACH resource may be a PRACH resource to which PRACH adaptation is not applied. The first PRACH resource does not have to be a PRACH resource that becomes available / unavailable based on DCI. The first PRACH resource may be configured based on configuration information for configuring the first PRACH resource (hereinafter, first PRACH configuration information). Here, the specific information may include the first PRACH configuration information. The first PRACH configuration information may include, for example, information for configuring parameters for the first PRACH resource. The first PRACH configuration information may include information indicating the first PRACH resource.

[0060] On the other hand, the second PRACH resource may be a PRACH resource configured for NES UE. The second PRACH resource may not be configurable for legacy UE. The second PRACH resource may be configurable only for UE that support NES, and may be configurable only for UE that support PRACH adaptation. The second PRACH resource may be a PRACH resource to which PRACH adaptation is applied. The second PRACH resource may be a PRACH resource that becomes available / unavailable based on DCI. As described above, the second PRACH resource may be configured based on second PRACH configuration information. That is, the second PRACH resource may be configured based on configuration information different from the first PRACH configuration information (i.e., second PRACH configuration information). For example, a second PRACH resource may be configured based on the second PRACH configuration information only if the specific information includes the first PRACH configuration information. As described below, the specific information (e.g., the first PRACH configuration information and / or the second PRACH configuration information) may be configured for each uplink bandwidth portion (BWP). That is, the first PRACH configuration information may be configured for one uplink bandwidth portion (BWP), and the second PRACH configuration information may be configured for that same uplink bandwidth portion (BWP).

[0061] A legacy UE may be a UE prior to the introduction of the PRACH adaptation, and may be UE100 prior to a specific release (e.g., release 18) of the technical specification developed before the introduction of the PRACH adaptation.

[0062] The second PRACH resource may be one or more PRACH resources. The second PRACH resource may also be referred to as a subset of the second PRACH resource, or as a second PRACH resource set, additional PRACH resource, etc. The second PRACH resource (and the first PRACH resource) may be, for example, a PRACH preamble index, a preamble SCS (Subcarrier Speccing), a PRACH resource (time resource, frequency resource), and / or the duration (period) of a PRACH opportunity, at least one of these. The second PRACH setting may be able to configure one or more PRACH resources. A subset of the second PRACH resource may be a portion of the PRACH opportunities set by the second PRACH resource or the PRACH preamble index of the first PRACH resource.

[0063] The second PRACH configuration information may include information for configuring a specific second PRACH resource (hereinafter referred to as "specific second PRACH configuration information"). This information may be information for providing a configuration for early paging indication (PEI) (pei-ConfigBWP). This information may include, for example, an identifier for a separate search space for PEI (e.g., pei-SearchSpace). The specific second PRACH resource may be, for example, a resource for PEI. The second PRACH configuration information may also include a search space configuration for paging, or a search space configuration for PEI. The search space for paging may also be referred to as the search space for monitoring PDCCH for DCI format 1_0 with CRC scrambled by P-RNTI, which is CRC scrambled with P-RNTI. The search space for PEI may also be referred to as the search space for monitoring PDCCH for DCI format 2_7 with CRC scrambled by PEI-RNTI, which is CRC scrambled with PEI-RNTI. In other words, DCI (DCI format) is transmitted as PDCCH. For example, UE100 may monitor PDCCH (also referred to as PDCCH candidate) according to the corresponding search space. UE100 may monitor the PDCCH in the downlink bandwidth portion (BWP) of a serving cell where PDCCH monitoring is configured, according to the search space. Here, UE100 may monitor the PDCCH in the CORESET in the downlink BWP. Here, monitoring may include receiving the corresponding PDCCH and / or decoding the PDCCH according to the corresponding DCI (DCI format).

[0064] Here, information for providing settings for PEI (pei-ConfigBWP), identifiers for individual search spaces for PEI (e.g., pei-SearchSpace), information for configuring search spaces for paging, and / or information for configuring search spaces for PEI may be included in the PDCCH configuration information (e.g., PDCCH-ConfigCommon). This PDCCH configuration information (e.g., PDCCH-ConfigCommon) may be included in the system information. For example, this PDCCH configuration information (e.g., PDCCH-ConfigCommon) may be included in SIB1. Furthermore, information for providing settings for PEI (pei-ConfigBWP), identifiers for individual search spaces for PEI (e.g., pei-SearchSpace), information for setting up search spaces for paging, and / or information for setting up search spaces for PEI may be set for each downlink bandwidth portion (BWP). Accordingly, this information may be associated with (or linked to) one or more downlink BWPs that are set up by information indicating downlink BWPs. For example, information used to set common parameters for downlink bandwidth portions (BWPs) (hereinafter referred to as BWP downlink common information (e.g., BWP-DownlinkCommon)) may include information used to set general parameters for bandwidth portions as information indicating downlink BWPs (e.g., "BWP").

[0065] The second PRACH setting information may include an identifier (hereinafter referred to as a determination identifier) ​​for associating one or more second PRACH resources with the PRACH availability field. For example, the determination identifier may indicate any bitmap information from a list of bitmap information in which one or more second PRACH resources are associated with the PRACH availability field. Here, the list is defined in the technical specification, and the control unit 120 of UE 100 may store the list in advance. Alternatively, the second PRACH setting information may include the list.

[0066] Secondly, the specific information may include information that (explicitly) indicates that the DCI includes the PRACH availability field (hereinafter referred to as availability information). The availability information may indicate that the DCI includes the PRACH availability field. If the RRC message does not include availability information, it may indicate that the DCI does not include the PRACH availability field.

[0067] Availability information may indicate whether multiple types of DCIs include the PRACH availability field, for example, if multiple types of DCIs can include the PRACH availability field. For example, availability information may indicate whether multiple types of DCIs include the PRACH availability field in common. For example, availability information may indicate whether all of the multiple types of DCIs include the PRACH availability field. Availability information may indicate independently whether multiple types of DCIs include the PRACH availability field. For example, availability information may be bitmap information consisting of multiple bits associated with multiple types of DCIs. Each bit constituting the bitmap information may be associated with each of the multiple types of DCIs. In the bitmap information, a first value (e.g., "1") may be set for the bit corresponding to the DCI that includes the PRACH availability field, and a second value (e.g., "0") may be set for the bit corresponding to the DCI that does not include the PRACH availability field.

[0068] Furthermore, multiple types of DCIs (i.e., DCIs that can include a PRACH availability field) may include, for example, "DCI format 1_0" and "DCI format 2_7". DCI format 1_0 may be a DCI (DCI format) used for scheduling (PDSCH) in a single DL cell (i.e., a serving cell). DCI format 1_0 may be a DCI (DCI format) used to notify the PRACH availability indication field. DCI format 2_7 may be a DCI (DCI format) used to notify paging early indication and TRS availability indication. DCI format 2_7 may be a DCI (DCI format) used to notify the PRACH availability indication field. In addition, a DCI that can include a PRACH availability field may be a cyclic redundancy check (CRC) scrambled DCI (DCI format) scrambled with a specific radio network temporary identifier (RNTI). The DCI may be a DCI (DCI format) to which a CRC (also called a CRC parity bit) scrambled with a predetermined radio network temporary identifier (RNTI) is added. For example, the DCI may be DCI format 1_0 with a CRC scrambled with a paging radio network temporary identifier (P-RNTI). The DCI may be DCI format 2_7 with a CRC scrambled with a paging early indication radio network temporary identifier (PEI-RNTI).

[0069] Furthermore, specific information may be set for each uplink bandwidth portion (BWP). Accordingly, specific information may be associated with (or linked to) one or more uplink BWPs set by information indicating an uplink BWP. The specific information associated with an uplink BWP set in UE100 may be information for determining whether the DCI transmitted in the uplink BWP includes a PRACH availability field. For example, information used to set common parameters for uplink bandwidth portions (BWPs) (hereinafter referred to as BWP uplink common information (e.g., BWP-UplinkCommon)) may include information used to set general parameters for the bandwidth portion as information indicating an uplink BWP (e.g., "BWP") and RACH setting common information. The specific information included in the RACH setting common information may be associated with an uplink BWP set by information indicating an uplink BWP within the BWP uplink common information. Alternatively, the BWP uplink common information may include information indicating the uplink BWP, RACH setting common information, and specific information outside of the said RACH setting common information. The information indicating the uplink BWP included in the BWP uplink common information may be associated with the specific information.

[0070] If the specific information is not the second PRACH setting information, the control unit 230 of the base station 200 may include the second PRACH setting information separately in the RRC message from the specific information. The transmission unit 211 of the base station 200 may also send the specific information to the UE 100 in an RRC message separate from the RRC message containing the second PRACH setting information.

[0071] Furthermore, the RRC message may include information indicating the validity period of the second PRACH resource (hereinafter referred to as validity period information). The control unit 230 of the base station 200 may include information used to determine the validity period as validity period information in the above-mentioned RRC message (system information and / or individual RRC message). The validity period of the second PRACH resource may indicate the period during which the second PRACH resource is available, or it may indicate the period during which the second PRACH resource is available as indicated by the PRACH availability indication. It may also indicate the period during which PRACH adaptation is available.

[0072] Step S102: The control unit 120 of UE100 may determine whether the DCI includes a PRACH availability field. The control unit 120 may determine whether a PRACH availability field exists in the DCI. The control unit 120 may determine (or assume) whether the DCI includes a PRACH availability field based on specific information. The control unit 120 may determine this using, for example, at least one of the following determination methods.

[0073] Firstly, the control unit 120 may determine whether the DCI includes the PRACH availability field based on specific information. For example, the control unit 120 may determine whether the DCI includes the PRACH availability field based on whether the RRC message includes specific information. If the RRC message includes specific information, the control unit 120 may determine that the DCI includes the PRACH availability field. On the other hand, if the RRC message does not include specific information, the control unit 120 may determine that the DCI does not include the PRACH availability field. Furthermore, the control unit 120 may determine whether the DCI includes the PRACH availability field based on whether a second PRACH resource is set up by the specific information. For example, if a second PRACH resource is set up, the control unit 120 may determine that the DCI includes the PRACH availability field. On the other hand, if a second PRACH resource is not set up, the control unit 120 may determine that the DCI does not include the PRACH availability field. For example, the control unit 120 may determine that the DCI includes the PRACH availability field if the specific information includes the second PRACH setting information. On the other hand, the control unit 120 may determine that the DCI does not include the PRACH availability field if the specific information does not include the second PRACH setting information.

[0074] That is, for example, the control unit 120 may determine that the DCI includes the PRACH availability field when the RRC message includes the second PRACH setting information (and therefore, the second PRACH setting information is set by the RRC message). On the other hand, the control unit 120 may determine that the DCI does not include the PRACH availability field when the RRC message does not include the second PRACH setting information (and therefore, the second PRACH setting information is not set by the RRC message).

[0075] Secondly, the control unit 120 may determine whether the DCI includes the PRACH availability field based on whether the availability information indicates that the DCI includes the PRACH availability field. If the availability information indicates that the DCI includes the PRACH availability field, the control unit 120 may determine that the DCI includes the PRACH availability field. Also, if the RRC message does not include availability information (for example, availability information indicating only "unavailable"), the control unit 120 may determine that the DCI includes the PRACH availability field. On the other hand, if the availability information does not indicate that the DCI includes the PRACH availability field, the control unit 120 may determine that the DCI does not include the PRACH availability field. Also, if the RRC message does not include availability information (for example, availability information indicating only "available"), the control unit 120 may determine that the DCI does not include the PRACH availability field.

[0076] Furthermore, the control unit 120 may determine, based on specific information, whether or not multiple types of DCI include a PRACH availability field. For example, if a second PRACH resource is set, and therefore the specific information includes second PRACH setting information, the control unit 120 may determine that the first DCI among the multiple types of DCI includes a PRACH availability field. The first DCI may be DCI format 1_0, or DCI format 1_0 scrambled with P-RNTI's CRC. For example, if the specific information includes second PRACH setting information, the control unit 120 may determine that the DCI format 1_0 scrambled with P-RNTI's CRC includes a PRACH availability field. The control unit 120 may also determine that the DCI format 1_0 includes a PRACH availability field if it successfully decodes the DCI format 1_0 scrambled with P-RNTI's CRC. In other words, the control unit 120 may determine that the first DCI includes a PRACH availability field if, for example, information for setting a search space for paging is set. The control unit 120 may also determine that the first DCI includes a PRACH availability field if second PRACH setting information is set and information for setting a search space for paging is set.

[0077] Furthermore, the control unit 120 may determine that, if a specific second PRACH resource is configured, and therefore the specific information includes specific second PRACH configuration information, the second DCI corresponding to the specific second PRACH resource also includes a PRACH availability field, in addition to the first DCI. The second DCI may be DCI format 2_7, or DCI format 2_7 scrambled with PEI-RNTI CRC. For example, if the specific information includes an identifier for a separate search space for PEI, the control unit 120 may determine that the DCI format 2_7 scrambled with PEI-RNTI CRC includes a PRACH availability field. The control unit 120 may also determine that the DCI format 2_7 includes a PRACH availability field if it successfully decodes the DCI format 2_7 scrambled with PEI-RNTI CRC. In other words, the control unit 120 may determine that the second DCI includes a PRACH availability field if, for example, information for providing settings for PEI (pei-ConfigBWP), an identifier for a separate search space for PEI (e.g., pei-SearchSpace), and / or information for setting up a search space for PEI is set. The control unit 120 may determine that the second DCI includes a PRACH availability field if the second PRACH setting information is set, and information for providing settings for PEI (pei-ConfigBWP), an identifier for a separate search space for PEI (e.g., pei-SearchSpace), and / or information for setting up a search space for PEI is set.

[0078] Furthermore, the control unit 120 will, of course, determine that a DCI other than the multiple types of DCIs that can include a PRACH availability field does not include a PRACH availability field when it receives such a DCI.

[0079] In this example, we will proceed with the assumption that UE100 has determined (assumed) that DCI contains the PRACH availability field. Furthermore, UE100 may perform at least the following processes.

[0080] The control unit 120 of UE100 may determine the number of bits (i.e., size) of the PRACH availability field. The control unit 120 may determine the number of bits of the PRACH availability field based on the number of PRACH resources set by the second PRACH setting information (for example, the number of PRACH settings included in the second PRACH setting information for setting PRACH resources). The number of PRACH resources may be the number of the second PRACH resources (or subsets thereof). The number of bits of the PRACH availability field may be a fixed number. For example, the number of bits of the PRACH availability field may be (always) 1 bit or 2 bits. The control unit 120 may determine the number of bits by at least one of the following methods.

[0081] Firstly, if only one PRACH resource is configured as the second PRACH resource, the number of bits in the PRACH availability field may always be set to 1 bit. The control unit 120 may determine the number of bits in the PRACH availability field to be 1 bit. For example, if the second PRACH resource is configured based on one PRACH setting included in the second PRACH setting information, the control unit 120 may determine the number of bits in the PRACH availability field to be 1 bit.

[0082] Secondly, when multiple PRACH resources are set as the second PRACH resource, the number of bits in the PRACH availability field may be set to be the same size as the multiple PRACH resources. The control unit 120 may determine the number of bits in the PRACH availability field as the number of PRACH resources set. For example, if two PRACH resources are set based on two PRACH settings included in the second PRACH setting information, the control unit 120 may determine the number of bits in the PRACH availability field to be 2 bits. Also, if three PRACH resources are set based on three PRACH settings included in the second PRACH setting information, the control unit 120 may determine the number of bits in the PRACH availability field to be 2 bits (or 3 bits). The control unit 120 may also determine the number of bits in the PRACH availability field based on the number of PRACH settings included in the second PRACH setting information for setting each of the multiple PRACH resources.

[0083] Thirdly, when multiple PRACH resources are set as the second PRACH resource, the control unit 120 may determine the number of bits based on the determination identifier. The control unit 120 may determine the number of bits based on the maximum value of the determination identifier (or the value of "maximum value + 1"). For example, the control unit 120 may determine the number of bits in the PRACH availability field based on the maximum value of the number of valid bits constituting the bitmap information indicated by the determination identifier (or the value of "maximum value + 1"). The maximum value of the number of valid bits (or the value of "maximum value + 1") may indicate one or the number of PRACH resources. The number of valid bits may be the last valid value (e.g., "1") among the values ​​(e.g., "0" and "1") set for each bit of the bitmap information. For example, an identifier (i.e., a determination identifier) ​​may be set (assigned) for each of the multiple PRACH resources set as the second PRACH resource. Also, each of the multiple PRACH resources to which an identifier has been set may correspond to each bit of the bitmap information. The control unit 120 may consider a corresponding PRACH resource to be valid if a bit in the bitmap information is set to "1" (for example, it may consider that the corresponding PRACH resource exists). The control unit 120 may also consider a corresponding PRACH resource to be invalid if a bit in the bitmap information is set to "0" (for example, it may consider that the corresponding PRACH resource does not exist). Furthermore, each bit in the PRACH availability field included in the DCI may correspond to each of a plurality of PRACH resources, and the control unit 120 may apply PRACH adaptation to the PRACH resource that it considers to be valid. The control unit 120 may determine the number of bits in the PRACH availability field based on the identifier set for the PRACH resource corresponding to the bit set to "1". For example, the control unit 120 may determine the number of bits in the PRACH availability field based on the maximum value (or "maximum value + 1") of the identifier set for the PRACH resource corresponding to the bit set to "1".

[0084] Fourth, if multiple PRACH resources are set as the second PRACH resource, the PRACH availability field may indicate the availability of all of the multiple PRACH resources. In this case, the control unit 120 may determine the number of bits in the PRACH availability field to be 1 bit.

[0085] Step S103: The transmitting unit 211 of the base station 200 transmits the DCI to the UE 100. The receiving unit 112 of the UE 100 receives the DCI from the base station 200.

[0086] The control unit 230 of the base station 200 may include the PRACH availability field in the DCI if the specific information indicates that the field is included. On the other hand, if the specific information does not indicate that the PRACH availability field is included, the control unit 230 does not need to include the field in the DCI.

[0087] The PRACH availability indicator field (PRACH availability field) may be a field on which a PRACH availability indicator is set. The PRACH availability field (i.e., PRACH availability indicator) may indicate the availability of a second PRACH resource. The PRACH availability field may indicate the availability of a PRACH adaptation. The PRACH availability field may be called a PRACH resource availability indicator or a PRACH adaptation indicator.

[0088] The control unit 120 of UE100 may receive DCI based on the second PRACH setting information. It may also receive DCI in the search space and / or CORESET set by the second PRACH setting information (and / or PDCCH setting information). For example, the control unit 120 may monitor DCI in the search space based on the second PRACH setting information (and / or PDCCH setting information). If a search space for paging is set in response to the setting of the second PRACH resource, the control unit 120 may monitor DCI format 1_0, which has been CRC scrambled with P-RNTI, in that search space. If a search space for PEI is set in response to the setting of the second PRACH resource, the control unit 120 may monitor DCI format 2_7, which has been CRC scrambled with PEI-RNTI, in that search space. When a search space for paging and a search space for PEI are set, the control unit 120 may monitor DCI format 1_0 scrambled with P-RNTI and / or DCI format 2_7 scrambled with PEI-RNTI.

[0089] For example, when the control unit 230 receives DCI format 1_0 scrambled with P-RNTI and / or DCI format 2_7 scrambled with PEI-RNTI based on the second PRACH setting information (and / or PDCCH setting information), it may determine that the received DCI includes a PRACH availability field. That is, the control unit 230 may monitor the DCI assuming that DCI format 1_0 scrambled with P-RNTI and / or DCI format 2_7 scrambled with PEI-RNTI include a PRACH availability field (i.e., it may attempt to decode the DCI).

[0090] Furthermore, the control unit 120 may determine whether the received DCI includes a PRACH availability field based on a short message indicator (hereinafter referred to as the SM indicator). The SM indicator may indicate whether or not a PRACH availability field exists in the received DCI (i.e., the DCI containing the SM indicator). In other words, the control unit 230 may determine whether or not a PRACH availability field exists in the DCI based on the value of the SM indicator in the DCI.

[0091] As shown in Figure 6, for example, if the SM indicator in the DCI is set to a predetermined value (for example, "01", "10", and "11"), it may be indicated that a PRACH availability field exists in the DCI. For example, if the second PRACH setting information (also referred to as PRACH adaptation resource set config) is set, the control unit 120 may determine that the DCI includes a PRACH availability field based on the value of the SM indicator in the DCI. On the other hand, if the DCI does not include an SM indicator showing the predetermined value, or if the second PRACH setting information (also referred to as PRACH adaptation resource set config) is not set, the control unit 120 may determine that the DCI does not include a PRACH availability field. In other words, the control unit 120 may determine that a PRACH availability field does not exist in the DCI if, for example, the SM indicator in the DCI is not set to a predetermined value (i.e., a value other than the predetermined value is set). Also, the control unit 120 may determine that a PRACH availability field does not exist in the DCI if the second PRACH setting information (also referred to as PRACH adaptation resource set config) is not set. Note that the DCI may be DCI format 1_0 scrambled with P-RNTI.

[0092] Furthermore, the control unit 120 of the UE 100 may determine the validity period of the second PRACH resource. The control unit 120 may determine the validity period of the second PRACH resource based on validity period information, for example. The control unit 120 may use, for example, a paging cycle (or default paging cycle) or an intermittent reception (DRX) cycle as validity period information. The control unit 120 may determine a period that is an integer multiple of the paging cycle (or default paging cycle) or DRX cycle as the validity period.

[0093] The control unit 120 may determine the start position of the validity period of the second PRACH resource. The control unit 120 may determine the start position of the validity period of the second PRACH resource based on, for example, the received DCI. For example, the control unit 120 may determine the start position of the validity period of the second PRACH resource based on the DCI reception timing. The reception timing may be at least one of the slot, symbol, or system frame number (SFN). The DCI reception timing may be the timing when the control unit 120 of the UE 100 detects the DCI.

[0094] Furthermore, the control unit 120 may determine the validity period of the second PRACH resource and / or the start position of the validity period based on at least one of the period-related information, such as the association period, association pattern period, SSB-RO mapping cycle, SFN, etc. The control unit 120 may also determine the validity period as a period that is an integer multiple of the period, such as the association period, association pattern period, SSB-RO mapping cycle, SFN, etc. The start position of the validity period may be predetermined. The control unit 120 may determine the start position of the validity period based on the predetermined start position of the validity period. The control unit 120 may also determine the start position of the validity period based on the above-mentioned periods.

[0095] For example, the control unit 120 may determine the start position of the validity period as the start position of the association period in which DCI was detected, or the start position of the association period following the association period in which DCI was detected. Alternatively, the control unit 120 may determine the start position of the validity period as the start position of the association pattern period in which DCI was detected, or the start position of the association pattern period following the association pattern period in which DCI was detected. Furthermore, the control unit 120 may determine the start position of the validity period as the start position of the system frame in which DCI was detected, or the start position of the system frame following the system frame in which DCI was detected. The association period, association pattern period, and SSB-RO mapping cycle may be determined based on a second PRACH resource. That is, a second association period, association pattern period, and SSB-RO mapping cycle separate from the first PRACH resource may be set. The control unit 120 may determine the validity period of the second PRACH resource and / or the start position of the validity period based on at least one of the period-related information, such as the second association period, association pattern period, SSB-RO mapping cycle, SFN, etc.

[0096] The control unit 120 of UE 100 may also determine the end of the validity period of the second PRACH resource. The control unit 120 may determine the end position of the validity period in the same way as the start position of the validity period. For example, the control unit 120 may determine the end position of the validity period of the second PRACH resource based on the received DCI. The control unit 120 may also determine the end position of the validity period based on at least one of the period-related information such as the association period, association pattern period, SSB-RO mapping cycle, SFN, etc.

[0097] Step S104: The control unit 120 of UE100 may determine a PRACH opportunity. If the DCI includes a PRACH availability field, the control unit 120 may determine whether a second PRACH resource is available based on the PRACH availability field.

[0098] For example, the PRACH availability field may be set to a first value as the PRACH availability indicator, indicating that the second PRACH resource is available. The PRACH availability field may also be set to a second value as the PRACH availability indicator, indicating that the second PRACH resource is unavailable. The control unit 120 may determine (estimate) that the second PRACH resource is available if the PRACH availability indicator shows a first value (e.g., "1"). On the other hand, if the PRACH availability indicator shows a second value (e.g., "0"), the control unit 120 may determine (estimate) that the second PRACH resource is unavailable. That is, the first value (e.g., "1") may indicate that the second PRACH resource is available (e.g., the second PRACH resource exists, or the second PRACH resource is active). Additionally, a second value (for example, "0") may indicate that the second PRACH resource is unavailable (for example, the second PRACH resource does not exist, or the second PRACH resource is not enabled (invalid)).

[0099] Alternatively, the PRACH availability field may be set to a second value (e.g., "0") as the PRACH availability indicator, indicating that there is no change from the current determination (or estimation) regarding the availability of the second PRACH resource. The control unit 120 may, as described above, determine (estimate) that the second PRACH resource is available if the PRACH availability indicator shows a first value (e.g., "1"). On the other hand, if the PRACH availability indicator shows a second value (e.g., "0"), the control unit 120 may determine that there is no change from the current determination (or estimation, assumption) regarding the availability of the second PRACH resource. That is, the second value (e.g., "0") may indicate that there is no change from the current determination (or estimation, assumption) regarding the availability (and / or unavailability) of the corresponding second PRACH resource. Therefore, after the control unit 120 determines (estimates) that the second PRACH resource is available, if the PRACH availability indicator in the subsequent DCI shows a second value, the control unit 120 may determine (estimate) that the second PRACH resource is available (until the validity period of the second PRACH resource has expired). On the other hand, after the control unit 120 determines (estimates) that the second PRACH resource is unavailable, if the PRACH availability indicator in the subsequent DCI shows a second value, the control unit 120 may determine (estimate) that the second PRACH resource is unavailable.

[0100] The control unit 120 may determine a PRACH opportunity based on the second PRACH resource (second PRACH setting information) if the second PRACH resource is available. Furthermore, if both the first and second PRACH resources are available, the control unit 120 may determine a PRACH opportunity based on both the first and second PRACH resources. Additionally, the control unit 120 may determine an earlier PRACH opportunity based on the first and second PRACH resources to be used for PRACH transmission.

[0101] On the other hand, if the DCI does not include the PRACH availability field, the control unit 120 may determine a PRACH opportunity based on the first PRACH resource (first PRACH setting information). Also, if the second PRACH resource is unavailable, the control unit 120 may determine a PRACH opportunity based on the first PRACH resource. Furthermore, if the validity period of the second PRACH resource has expired, the control unit 120 may determine a PRACH opportunity based on the first PRACH resource, even if the second PRACH resource is available.

[0102] The control unit 120 may start a timer for counting the validity period from the start position of the validity period. For example, if the timer is running and a second PRACH resource is available, the control unit 120 may determine a PRACH opportunity based on the second PRACH resource. In response to the expiration of the timer, the control unit 120 may determine a PRACH opportunity based on the first PRACH resource until the second PRACH resource becomes available again.

[0103] Step S105: The transmitter 111 of UE100 performs a PRACH transmission at the determined PRACH opportunity. The receiver 212 of base station 200 receives the PRACH from UE100.

[0104] As described above, the receiving unit 112 of the UE 100 may receive the DCI from the base station 200. The control unit 120 may determine whether the second PRACH resource is available based on the PRACH availability field if the DCI includes a field indicating the availability of the second PRACH resource. The receiving unit 112 may receive an RRC message from the base station 200 that includes specific information for determining whether the DCI includes the PRACH availability field. The control unit 120 may determine whether the DCI includes the PRACH availability field based on the specific information. As a result, the UE 100 can determine whether the received DCI includes the PRACH availability field, and thus can perform PRACH adaptation appropriately.

[0105] Furthermore, the RRC message may include system information containing specific information. This allows the UE100 to receive specific information even when it is idle. Consequently, the idle UE100 can perform PRAC transmission through PRAC adaptation, thus saving network energy.

[0106] Furthermore, the specific information may include second PRACH configuration information for configuring a second PRACH resource. This allows UE 100 to determine whether DCI includes the PRACH availability field when the second PRACH resource is available. UE 100 does not need to determine that DCI includes the PRACH availability field when the second PRACH resource is unavailable, thus enabling power savings.

[0107] Furthermore, multiple PRACH resources may be configured as the second PRACH resource. The control unit 120 may determine the number of bits in the PRACH availability field based on the number of PRACH resources configured by the configuration information. This allows the UE 100 to appropriately determine the number of bits even when the number of bits changes based on the number of PRACH resources.

[0108] Furthermore, specific information may be set for each uplink bandwidth portion (BWP). This allows the UE100 to determine whether the DCI includes the PRACH availability field for each uplink BWP, even if multiple uplink BWPs are configured. As a result, PRACH adaptation can be controlled flexibly.

[0109] Furthermore, multiple types of DCIs may include a PRACH availability field. The control unit 120 may determine, based on specific information, whether or not multiple types of DCIs include a PRACH availability field. This allows the UE 100 to understand whether or not the received DCIs include a PRACH availability field, even when PRACH adaptation can be controlled by multiple types of DCIs, thereby enabling appropriate PRACH adaptation.

[0110] Furthermore, the receiving unit 112 may receive the DCI format 1_0, which has been CRC scrambled with P-RNTI, as a DCI. The control unit 120 may determine that the DCI format 1_0 contains a PRACH availability field if the specific information includes setting information for setting a second PRACH resource. As a result, when the UE 100 receives the DCI format 1_0, which has been CRC scrambled with P-RNTI, if a second PRACH resource is set, it can determine that the DCI contains a PRACH availability field. Therefore, it can determine whether or not the DCI format 1_0 contains a PRACH availability field, and thus can perform PRACH adaptation appropriately.

[0111] Furthermore, the receiving unit 112 may receive DCI format 2_7, which has been scrambled with cyclic redundancy check (CRC) using the Paging Early Indication Wireless Network Temporary Identifier (PEI-RNTI), as DCI. The control unit 120 may determine that DCI format 2_7 includes a PRACH availability field if the specific information further includes an identifier for a separate search space for PEI. This allows the system to determine whether or not DCI format 2_7 includes a PRACH availability field, thereby enabling appropriate PRACH adaptation.

[0112] Furthermore, the PRACH availability field may be set to a value indicating that there has been no change from the current determination regarding the availability of the second PRACH resource. This prevents a UE that has the second PRACH resource available from making unnecessary PRACH transmissions using the second PRACH resource if it fails to receive a DCI indicating that the resource is unavailable. In addition, if UE 100 fails to receive a DCI that may include the PRACH availability field, it may be controlled not to perform a transmission using the second PRACH resource, even if the previous DCI indicated that the second PRACH resource was available.

[0113] Furthermore, the DCI may include an SM indicator that indicates whether or not a field exists within the DCI. The control unit 120 may determine, based on the SM indicator, whether or not the received DCI contains a PRACH availability field. This allows the UE 100 to understand whether or not the received DCI actually contains a PRACH availability field, thereby enabling it to perform PRACH adaptation appropriately.

[0114] Furthermore, the RRC message may include information indicating the validity period of the second PRACH resource. This prevents, for example, UE100 from continuing to use the second PRACH resource after it has been set up, allowing for proper control of the second PRACH resource.

[0115] Furthermore, the control unit may determine the start position of the validity period of the second PRACH resource based on the received DCI. This makes it possible to avoid, for example, the validity period of the second PRACH resource expiring before the DCI is received.

[0116] (Other Embodiments) In the above-described embodiment, the control unit 120 of UE100 may perform the processing in step S102 after receiving the DCI. For example, the control unit 120 may determine whether or not the DCI includes a PRACH availability field after receiving the DCI.

[0117] In the embodiments described above, a mobile communication system based on NR was used as an example for the mobile communication system 1. However, the mobile communication system 1 is not limited to this example. The mobile communication system 1 may be a system compliant with a TS of either LTE (Long Term Evolution) or another generation system of the 3GPP standard (e.g., 6th generation). The base station 200 may be an eNB that provides E-UTRA user plane and control plane protocol terminations directed to UE100 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 IAB node.

[0118] The steps in the operation of the above-described embodiment do not necessarily have to be executed chronologically in the order described in the flowchart or sequence diagram. For example, the steps in the operation may be executed in a different order than that described in the flowchart or sequence diagram, or they may be executed in parallel. Also, some steps in the operation may be deleted, or further steps may be added to the process. Furthermore, each of the above-described operation flows can be implemented not only separately and independently, but also by combining two or more 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.

[0119] A program may be provided that causes a computer to execute each process performed by the UE 100 or base station 200. The program may be recorded on a computer-readable medium. Using a computer-readable medium, it is possible to install the program on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transient recording medium. The non-transient recording medium is not particularly limited, but may be a recording medium such as a CD-ROM (Compact Disk Read Only Memory) or a DVD-ROM (Digital Versatile Disc Read Only Memory). Alternatively, the circuits that execute each process performed by the UE 100 or base station 200 may be integrated, and at least a part of the UE 100 or base station 200 may be configured as a semiconductor integrated circuit (chipset, SoC (System On Chip)).

[0120] In the embodiments described above, "transmit" may mean processing at least one layer in the protocol stack used for transmission, or it may mean physically transmitting a signal wirelessly or via a wire. Alternatively, "transmit" may mean a combination of processing at least one layer and physically transmitting a signal wirelessly or via a wire. Similarly, "receive" may mean processing at least one layer in the protocol stack used for reception, or it may mean physically receiving a signal wirelessly or via a wire. Alternatively, "receive" may mean a combination of processing at least one layer and physically receiving a signal wirelessly or via a wire. Similarly, "obtain / acquire" may mean obtaining information from stored information, obtaining information from information received from another node, or obtaining information by generating it. Similarly, the phrases “based on” and “depending on / in response to” do not mean “based solely on” or “in response to” unless otherwise specified. The phrase “based on” means both “based solely on” and “at least partially on.” Similarly, the phrase “in response” means both “at least partially on” and “in at least partially on.” Similarly, “include” and “comprise” do not mean “include only the listed items,” but rather “may include only the listed items, or may include additional items in addition to the listed items.” Similarly, in this disclosure, “or” does not mean exclusive OR, but rather logical OR. Furthermore, any reference to elements using designations such as “first,” “second,” etc., as used in this disclosure does not limit the quantity or order of those elements in general. These designations may be used in this disclosure as a convenient way to distinguish between two or more elements.Therefore, references to the first and second elements do not imply that only two elements may be adopted therein, or that the first element must precede the second element in any way. In this disclosure, where articles are added by translation, such as a, an, and the in English, these articles shall be plural unless it is clearly indicated from the context that they are not.

[0121] This disclosure is described in accordance with the embodiments, but it is understood that this disclosure is not limited to such embodiments or structures. This disclosure also includes various modifications and variations within the equivalence. In addition, various combinations and forms, as well as other combinations and forms that include only one, more, or fewer of those elements, fall within the scope and concept of this disclosure.

[0122] (Note) The features of the above-described embodiment are noted below.

[0123] (Note 1) A communication device comprising: a receiving unit (111) that receives a random access setting from a base station (200) using system information, which includes first setting information including information indicating a first physical random access channel (PRACH) resource, and a control unit (120) that receives downlink control information (DCI) from the base station, wherein the control unit determines, based on second setting information including information indicating a second PRACH resource included in the random access setting, that the DCI includes a bit indicating the availability of the second PRACH resource as indicated by the information indicating the second PRACH resource, and determines whether the second PRACH resource is available or not based on the value of the bit indicating the availability of the second PRACH resource.

[0124] (Note 2) The communication device according to Note 1, wherein the control unit determines that the second PRACH resource is available when the value of the bit indicates "1".

[0125] (Note 3) The communication device according to Note 1 or 2, wherein the control unit determines that the DCI includes the bit when the random access setting includes the second setting information.

[0126] (Note 4) The communication device according to any one of Notes 1 to 3, wherein the system information includes information indicating the validity period for the value of the bit indicating that the second PRACH resource is available, the control unit determines the start position of the validity period based on the reception of DCI including the value of the bit indicating that the second PRACH resource is available, and determines that the second PRACH resource is available during the validity period indicated based on the information indicating the validity period of the second PRACH resource.

[0127] (Note 5) The second configuration information, which includes information indicating the second PRACH resource, is set for each uplink bandwidth portion (BWP) in the communication device according to any one of Notes 1 to 4.

[0128] (Note 6) A base station comprising a transmitting unit (211) that transmits a random access setting to a communication device (100) using system information, the setting including first setting information including information indicating a first physical random access channel (PRACH) resource, the transmitting unit transmits downlink control information (DCI) to the communication device, the random access setting includes second setting information including information indicating a second PRACH resource, the second setting information is used by the communication device to determine that the DCI includes a bit indicating the availability of the second PRACH resource as indicated by the information indicating the second PRACH resource, and the value of the bit indicating the availability of the second PRACH resource is used by the communication device to determine whether the second PRACH resource is available or not.

[0129] (Note 7) The base station described in Note 6, which is determined to have the second PRACH resource available when the value of the bit is "1".

[0130] (Note 8) The base station according to Note 6 or 7, in which the DCI is determined to include the bit if the random access setting includes the second setting information.

[0131] (Note 9) The base station according to any one of Notes 6 to 8, wherein the system information includes information indicating the validity period for the value of the bit indicating that the second PRACH resource is available.

[0132] (Note 10) The second configuration information, which includes information indicating the second PRACH resource, is set for each uplink bandwidth portion (BWP) and is a base station as described in any one of Notes 6 to 9.

[0133] (Note 11) A communication method performed by a communication device (100), comprising: receiving a random access setting from a base station (200) using system information, which includes a first setting information including information indicating a first physical random access channel (PRACH) resource; receiving downlink control information (DCI) from the base station; determining, based on a second setting information including information indicating a second PRACH resource included in the random access setting, that the DCI includes a bit indicating the availability of the second PRACH resource as indicated by the information indicating the second PRACH resource; and determining, based on the value of the bit indicating the availability of the second PRACH resource, whether or not the second PRACH resource is available.

[0134] (Note 12) The communication method according to Note 11, further comprising the step of determining that the second PRACH resource is available if the value of the bit indicates "1".

[0135] (Note 13) The communication method according to Note 11 or 12, further comprising the step of determining that the DCI includes the bit when the random access setting includes the second setting information.

[0136] (Note 14) The communication method according to any one of Notes 11 to 13, comprising: the steps of: determining the start position of the validity period based on the receipt of a DCI including the value of the bit indicating that the second PRACH resource is available; and determining that the second PRACH resource is available during the validity period indicated based on the information indicating the validity period of the second PRACH resource.

[0137] (Note 15) The second configuration information, which includes information indicating the second PRACH resource, is set for each uplink bandwidth portion (BWP) in the communication method described in any one of Notes 11 to 14.

[0138] (Note 16) A communication method performed at a base station (209), comprising the steps of: transmitting a random access setting to a communication device using system information, the setting including first setting information including information indicating a first physical random access channel (PRACH) resource; and transmitting downlink control information (DCI) to the communication device, wherein the random access setting includes second setting information including information indicating a second PRACH resource, the second setting information is used by the communication device to determine that the DCI includes a bit indicating the availability of the second PRACH resource as indicated by the information indicating the second PRACH resource, and the value of the bit indicating the availability of the second PRACH resource is used by the communication device to determine whether the second PRACH resource is available.

[0139] (Note 17) A communication device comprising: a receiving unit that receives downlink control information (DCI) from a base station; and a control unit that determines whether a second PRACH resource is available based on a field indicating the availability of a second PRACH resource that can be added separately from a first physical random access channel (PRACH) resource, wherein the receiving unit receives a radio resource control (RRC) message from the base station that includes specific information for determining whether the DCI includes the field; and the control unit determines whether the DCI includes the field based on the specific information.

[0140] (Note 18) The RRC message is a communication device as described in Note 17, which includes system information including the specific information.

[0141] (Note 19) The communication device described in Note 17 or 18, wherein the specified information includes setting information for setting the second PRACH resource.

[0142] (Note 20) The communication device according to Note 19, wherein multiple PRACH resources can be set as the second PRACH resource, and the control unit determines the number of bits in the field based on the number of PRACH resources set by the setting information.

[0143] (Note 21) The specified information is set for each uplink bandwidth portion (BWP) of the communication device described in any one of Notes 17 to 20.

[0144] (Note 22) A communication device according to any one of Notes 17 to 21, wherein multiple types of DCI can include the field, and the control unit determines whether or not the multiple types of DCI include the field based on the specific information.

[0145] (Note 23) The communication device according to any one of Notes 17 to 22, wherein the receiving unit receives a DCI format 1_0 scrambled with a paging wireless network temporary identifier (P-RNTI) using cyclic redundancy check (CRC) as the DCI, and the control unit determines that the DCI format 1_0 contains the field if the specific information includes configuration information for setting the second PRACH resource.

[0146] (Note 24) The communication device according to Note 23, wherein the receiving unit receives a DCI format 2_7 scrambled with a Paging Early Indication Radio Network Temporary Identifier (PEI-RNTI) as the DCI, and the control unit determines that the DCI format 2_7 contains the field if the identifying information further includes an identifier for a separate search space for the PEI.

[0147] (Note 25) The communication device according to any one of Notes 17 to 24, wherein the field can be set to a value indicating that there is no change from the current determination regarding the availability of the second PRACH resource.

[0148] (Note 26) The DCI includes a short message indicator that indicates whether or not the field exists within the DCI, and the control unit determines whether or not the received DCI includes the field based on the short message indicator. (Communication device according to any one of Notes 17 to 25)

[0149] (Note 27) The communication device according to any one of Notes 17 to 26, wherein the RRC message includes information indicating the validity period of the second PRACH resource.

[0150] (Note 28) The communication device according to any one of Notes 17 to 27, wherein the control unit determines the starting position of the validity period of the second PRACH resource based on the received DCI.

[0151] (Note 29) A base station comprising: a control unit that includes in downlink control information (DCI) a field indicating the availability of a second PRACH resource that can be added separately from a first physical random access channel (PRACH) resource; and a transmission unit that transmits a radio resource control (RRC) message to a communication device that includes specific information for determining whether the DCI includes the field.

[0152] (Note 30) A communication method performed by a communication device, comprising: receiving downlink control information (DCI) from a base station; determining whether a second PRACH resource is available based on a field indicating the availability of a second PRACH resource that can be added separately from a first physical random access channel (PRACH) resource, if the DCI includes a field indicating the availability of the second PRACH resource; receiving a radio resource control (RRC) message from the base station that includes specific information for determining whether the DCI includes the field; and determining whether the DCI includes the field based on the specific information.

Claims

1. A communication device comprising: a receiving unit (111) that receives a random access setting from a base station (200) using system information, which includes first setting information including information indicating a first physical random access channel (PRACH) resource, and a control unit (120) that receives downlink control information (DCI) from the base station, wherein the control unit determines, based on second setting information including information indicating a second PRACH resource included in the random access setting, that the DCI includes a bit indicating the availability of the second PRACH resource as indicated by the information indicating the second PRACH resource, and determines whether the second PRACH resource is available or not based on the value of the bit indicating the availability of the second PRACH resource.

2. The communication device according to claim 1, wherein the control unit determines that the second PRACH resource is available when the value of the bit indicates "1".

3. The communication device according to claim 1 or 2, wherein the control unit determines that the DCI includes the bit when the random access setting includes the second setting information.

4. The communication device according to claim 1 or 2, wherein the system information includes information indicating the validity period for the value of the bit indicating that the second PRACH resource is available, the control unit determines the start position of the validity period based on the reception of a DCI including the value of the bit indicating that the second PRACH resource is available, and determines that the second PRACH resource is available during the validity period indicated based on the information indicating the validity period of the second PRACH resource.

5. The communication device according to claim 1 or 2, wherein the second configuration information, which includes information indicating the second PRACH resource, is set for each uplink bandwidth portion (BWP).

6. A base station comprising a transmitting unit (211) that transmits a random access setting to a communication device (100) using system information, the transmitting unit transmitting downlink control information (DCI) to the communication device, the random access setting including second setting information including information indicating a second PRACH resource, the second setting information used by the communication device to determine that the DCI includes a bit indicating the availability of the second PRACH resource as indicated by the information indicating the second PRACH resource, and the value of the bit indicating the availability of the second PRACH resource used by the communication device to determine whether the second PRACH resource is available.

7. The base station according to claim 6, wherein the value of the bit indicates "1", and the second PRACH resource is determined to be available.

8. The base station according to claim 6 or 7, wherein the DCI is determined to include the bit when the random access setting includes the second setting information.

9. The base station according to claim 6 or 7, wherein the system information includes information indicating the validity period for the value of the bit indicating that the second PRACH resource is available.

10. The base station according to claim 6 or 7, wherein the second configuration information, which includes information indicating the second PRACH resource, is configured for each uplink bandwidth portion (BWP).

11. A communication method performed by a communication device (100), comprising: receiving a random access setting from a base station (200) using system information, which includes a first setting information including information indicating a first physical random access channel (PRACH) resource; receiving downlink control information (DCI) from the base station; determining, based on a second setting information including information indicating a second PRACH resource included in the random access setting, that the DCI includes a bit indicating the availability of the second PRACH resource as indicated by the information indicating the second PRACH resource; and determining, based on the value of the bit indicating the availability of the second PRACH resource, whether or not the second PRACH resource is available.

12. The communication method according to claim 11, further comprising the step of determining that the second PRACH resource is available if the value of the bit indicates "1".

13. The communication method according to claim 11 or 12, further comprising the step of determining that the DCI includes the bit if the random access setting includes the second setting information.

14. The communication method according to claim 11 or 12, comprising: determining the start position of the validity period based on the reception of a DCI including the value of the bit indicating that the second PRACH resource is available; and determining that the second PRACH resource is available during the validity period indicated based on the information indicating the validity period of the second PRACH resource.

15. The communication method according to claim 11 or 12, wherein the second configuration information, which includes information indicating the second PRACH resource, is set for each uplink bandwidth portion (BWP).

16. A communication method performed at a base station (209), comprising the steps of: transmitting a random access setting to a communication device using system information, the setting including first setting information including information indicating a first physical random access channel (PRACH) resource; and transmitting downlink control information (DCI) to the communication device, wherein the random access setting includes second setting information including information indicating a second PRACH resource, the second setting information is used by the communication device to determine that the DCI includes a bit indicating the availability of the second PRACH resource as indicated by the information indicating the second PRACH resource, and the value of the bit indicating the availability of the second PRACH resource is used by the communication device to determine whether the second PRACH resource is available.

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