Communication device, base station, and communication method

Abstract

A communication device (100) according to one embodiment comprises: a reception unit (112) that receives, from a cell, a short message including information indicating a warning message related to a PWS; and a control unit (120). The control unit performs control to acquire an SIB1 message from the cell on-demand on the basis of reception of a positive acknowledgement to information requesting on-demand SIB1, immediately acquire the SIB1 message from the cell on the basis of reception of the short message, and acquire a predetermined SIB related to the PWS on the basis of scheduling information included in the SIB1 message.

Description

Communication device, base station, and communication method CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on and claims the benefit of priority from patent application serial number 2024-120633, filed July 25, 2024, the entire contents of which are incorporated herein by reference.

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

[0003] 3GPP (Third Generation Partnership Project, a registered trademark; the same applies hereinafter), a standardization project for mobile communication systems, is currently discussing Network Energy Saving (NES). As one NES feature, the introduction of System Information Block Type 1 (hereinafter referred to as "on-demand SIB1"), which is transmitted upon request from a communication device, is being considered (see, for example, Non-Patent Document 1). A cell supporting on-demand SIB1 (hereinafter referred to as "NES cell") can save energy by eliminating the need to periodically transmit SIB1.

[0004] 3GPP contribution “R2-2405295” (Discussion on On-demand SIB1)

[0005] A communication device according to a first aspect includes a receiver configured to receive a short message from a cell, the short message including information indicating a warning message related to a public warning system (PWS), and a controller configured to: retrieve an on-demand system information block 1 (SIB1) message from the cell on demand based on reception of an acknowledgment to information requesting an on-demand SIB1; immediately retrieve the SIB1 message from the cell based on reception of the short message; and retrieve a predetermined SIB related to the PWS based on scheduling information included in the SIB1 message.

[0006] A base station according to a second aspect includes a transmitter configured to transmit a master information block (MIB) from a cell to a communication device, the transmitter configured to transmit a physical downlink control channel in accordance with at least one of CORESET#0 and search space#0 indicated using information included in the MIB when a short message including information indicating a warning message related to a public warning system (PWS) is transmitted from the cell to the communication device, and the transmitter configured to transmit a physical downlink control channel in accordance with at least one of information indicating CORESET#0 and search space#0 included in configuration information for acquiring on-demand system information block 1 (on-demand SIB1) when information requesting on-demand system information block 1 (on-demand SIB1) is received from the communication device.

[0007] A communication method according to a third aspect is a communication method executed by a communication device, the communication method comprising the steps of receiving a short message from a cell including information indicating a warning message related to a public warning system (PWS), retrieving an on-demand system information block 1 (SIB1) message from the cell on demand based on receipt of an acknowledgment for information requesting an on-demand SIB1, immediately retrieving the SIB1 message from the cell based on receipt of the short message, and controlling retrieval of a predetermined SIB related to the PWS based on scheduling information included in the SIB1 message.

[0008] Objects, features, advantages, etc. of the present disclosure will become clearer from the following detailed description taken in conjunction with the accompanying drawings. FIG. 1 is a diagram illustrating a configuration of a mobile communication system according to an embodiment. FIG. 2 is a diagram illustrating an example configuration of a protocol stack according to an embodiment. FIG. 3 is a diagram illustrating a configuration of a UE according to an embodiment. FIG. 4 is a diagram illustrating a configuration of a base station according to an embodiment. FIG. 5 is a diagram illustrating a first embodiment. FIG. 6 is a sequence diagram (part 1) illustrating the first embodiment. FIG. 7 is a sequence diagram (part 2) illustrating the first embodiment. FIG. 8 is a sequence diagram illustrating a first modified example of the first embodiment. FIG. 9 is a flowchart illustrating a second modified example of the first embodiment. FIG. 10 is a flowchart illustrating a second embodiment. FIG. 11 is a flowchart illustrating a first modified example of the second embodiment. FIG. 12 is a flowchart illustrating a second modified example of the second embodiment. FIG. 13 is a flowchart illustrating a third embodiment. FIG. 14 is a flowchart illustrating a first modified example of the third embodiment. FIG. 15 is a flowchart illustrating a second modified example of the third embodiment. Fig. 16 is a flowchart for explaining a third modified example of the third embodiment, Fig. 17 is a flowchart for explaining a fourth modified example of the third embodiment, and Fig. 18 is a flowchart for explaining a fifth modified example of the third embodiment.

[0009] A mobile communication system according to an embodiment will be described with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[0010] An object of the present disclosure is to provide a communication device, a base station, and a communication method that enable a communication device to properly acquire SIB1 of an NES cell.

[0011] (System Configuration) First, the configuration of a mobile communication system 1 according to this embodiment will be described with reference to Fig. 1. The mobile communication system 1 is, for example, a system that complies with the 3GPP Technical Specification (TS). In the following, the mobile communication system 1 will be described using as an example a 5th Generation System (5G system) of the 3GPP standard, i.e., a mobile communication system based on NR (NR (New Radio) radio access).

[0012] 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 a next generation radio access network (NG-RAN) 20, which is a 5G radio access network, and a 5G core network (5GC) 30, which is a 5G core network.

[0013] The UE 100 is a communication device that communicates via the base station 200. The UE 100 may be a device used by a user. The UE 100 may be a mobile device such as a mobile phone terminal such as a smartphone, a tablet terminal, a laptop PC, a communication module, or a communication card. The UE 100 may be a vehicle (e.g., a car, a train, etc.) or a device provided therein (e.g., a Vehicle UE). The UE 100 may be a transport vehicle other than a vehicle (e.g., a ship, an airplane, etc.) or a device provided therein (e.g., an Aerial UE). The UE 100 may be a sensor or a device provided therein. Note that the UE 100 may be referred to by other names such as a terminal, a terminal device, a mobile station, a mobile terminal, a mobile device, a mobile unit, a subscriber station, a subscriber terminal, a subscriber device, a subscriber unit, a wireless station, a wireless terminal, a wireless device, a wireless unit, a remote station, a remote terminal, a remote device, or a remote unit. Furthermore, the UE 100 is an example of a terminal, and the terminal may include factory equipment or the like.

[0014] The NG-RAN 20 includes multiple 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 with a cell, or a cell may be replaced with 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 refer to wireless communication resources or to a communication target of the UE 100. Each base station 200 can perform wireless communication with the UE 100 located in its own cell. The base station 200 communicates with the UE 100 using a RAN protocol stack. Details of the protocol stack will be described later. Furthermore, the base station 200 is connected to other base stations 200 (which may be referred to as neighbor base stations) via an Xn interface. The base station 200 communicates with the neighbor base stations via the Xn interface. In addition, the base station 200 provides NR user plane and control plane protocol termination for the UE 100 and is connected to the 5GC 30 via an NG interface. Such an NR base station 200 is sometimes referred to as a gNodeB (gNB).

[0015] The 5GC 30 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 UE 100. The UPF provides functions specialized for U-plane processing. The AMF and the UPF are connected to the base station 200 via an NG interface.

[0016] (Configuration Example of Protocol Stack) Next, a configuration example of a protocol stack according to this embodiment will be described with reference to FIG.

[0017] The protocol of the wireless section between UE 100 and base station 200 includes a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, and a radio resource control (RRC) layer.

[0018] The PHY layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Data and control information are transmitted between the PHY layer of the UE 100 and the PHY layer of the base station 200 via a physical channel.

[0019] The MAC layer performs data priority control, retransmission processing using Hybrid ARQ (HARQ), random access procedures, etc. Data and control information are transmitted between the MAC layer of UE 100 and the MAC layer of base station 200 via a transport channel. The MAC layer of base station 200 includes a scheduler. The scheduler determines the uplink and downlink transport format (transport block size, modulation and coding scheme (MCS)) and the resources to be allocated to UE 100.

[0020] The RLC layer transmits data to the RLC layer on the receiving side using the functions of the MAC layer and the PHY layer. Data and control information are transmitted between the RLC layer of the UE 100 and the RLC layer of the base station 200 via logical channels.

[0021] The PDCP layer performs header compression / decompression and encryption / decryption.

[0022] A Service Data Adaptation Protocol (SDAP) layer may be provided as an upper layer above the PDCP layer. The SDAP layer maps IP flows, which are units for Quality of Service (QoS) control by the core network, to radio bearers, which are units for QoS control by an Access Stratum (AS).

[0023] The RRC layer controls logical channels, transport channels, and physical channels according to the establishment, re-establishment, and release of radio bearers. RRC signaling for various settings is transmitted between the RRC layer of the UE 100 and the RRC layer of the base station 200. When there is an RRC connection between the RRC layer of the UE 100 and the RRC layer of the base station 200, the UE 100 is in an RRC connected state. When there is no RRC connection between the RRC layer of the UE 100 and the RRC layer of the base station 200, the UE 100 is in an RRC idle state. When the RRC connection between the RRC layer of the UE 100 and the RRC layer of the base station 200 is suspended, the UE 100 is in an RRC inactive state.

[0024] The NAS layer, which is located above the RRC layer in the UE 100, performs session management and mobility management for the UE 100. NAS signaling is transmitted between the NAS layer of the UE 100 and the NAS layer of the core network device 300.

[0025] The UE 100 has an application layer and the like in addition to the radio interface protocol.

[0026] (Radio Frame Configuration) In a 5G system, downlink transmission and uplink transmission are configured within a radio frame having a duration of 10 ms. For example, a radio frame is represented by a system frame number (SFN) ranging from 0 to 1023. For example, a radio frame is configured with 10 subframes. For example, one subframe may be 1 ms. Furthermore, one subframe may be configured with one or more slots. For example, the number of symbols that make up one slot is 14 for a normal CP (Cyclic Prefix) and 12 for an extended CP. Furthermore, the number of slots that make up one subframe varies depending on the set subcarrier spacing. For example, for a normal CP, if the subcarrier spacing is set to 15 kHz, the number of slots per subframe is 1 (i.e., 14 symbols); if the subcarrier spacing is set to 30 kHz, the number of slots per subframe is 2 (i.e., 28 symbols); if the subcarrier spacing is set to 60 kHz, the number of slots per subframe is 4 (i.e., 56 symbols); and if the subcarrier spacing is set to 120 kHz, the number of slots per subframe is 8 (i.e., 112 symbols). Furthermore, if the subcarrier spacing is set to 60 kHz for an extended CP, the number of slots per subframe is 4 (i.e., 48 symbols). That is, the number of slots constituting one subframe is determined based on the subcarrier spacing set by the base station 200. Furthermore, the number of symbols constituting one subframe is determined based on the subcarrier spacing set by the base station 200. That is, the number of symbols constituting a 1 ms subframe is determined based on the subcarrier spacing set by the base station 200, and the length of each symbol (length in the time direction) changes.

[0027] (Configuration of User Equipment) The configuration of the UE 100 according to the embodiment will be described with reference to Fig. 3. The UE 100 includes a communication unit 110 and a control unit 120.

[0028] The communication unit 110 performs wireless communication with the base station 200 by transmitting and receiving radio signals to and from the base station 200. The communication unit 110 has at least one transmission unit 111 and at least one reception unit 112. The transmission unit 111 and the reception unit 112 may be configured to include multiple antennas and RF (Radio Frequency) circuits. The antenna converts a signal into radio waves and radiates the radio waves into space. The antenna also receives radio waves in space and converts the radio waves into a signal. The RF circuit performs analog processing of the signal transmitted and received via the antenna. The RF circuit may include a high-frequency filter, an amplifier, a modulator, a low-pass filter, etc.

[0029] The control unit 120 performs various controls in the UE 100. The control unit 120 controls communication with the base station 200 via the communication unit 110. The operations of the UE 100 described above and below may be operations controlled by the control unit 120. The control unit 120 may include at least one processor capable of executing a program and a memory that stores the program. The processor may execute the program to perform the operations of the control unit 120. The control unit 120 may include a digital signal processor that performs digital processing of signals transmitted and received via the antenna and the RF circuit. The digital processing includes processing of a RAN protocol stack. The memory stores the program executed by the processor, parameters related to the program, and data related to the program. The memory may include at least one of read-only memory (ROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), random access memory (RAM), and flash memory. All or a portion of the memory may be contained within the processor.

[0030] (Configuration of Base Station) The configuration of the base station 200 according to this embodiment will be described with reference to Fig. 4. The base station 200 includes a communication unit 210, a network communication unit 220, and a control unit 230.

[0031] The communication unit 210 receives, for example, a radio signal from the UE 100 and transmits the radio signal to the UE 100. The communication unit 210 has at least one transmission unit 211 and at least one reception unit 212. The transmission unit 211 and the reception unit 212 may be configured to include an RF circuit. The RF circuit performs analog processing of signals transmitted and received via an antenna. The RF circuit may include a high-frequency filter, an amplifier, a modulator, a low-pass filter, etc.

[0032] The network communication unit 220 transmits and receives signals to and from the network. For example, the network communication unit 220 receives signals from adjacent base stations connected via an Xn interface, which is an interface between base stations, and transmits the signals to the adjacent base stations. The network communication unit 220 also receives signals from the core network device 300 connected via an NG interface, and transmits the signals to the core network device 300.

[0033] The control unit 230 performs various controls in the base station 200. The control unit 230 controls, for example, communication with the UE 100 via the communication unit 210. The control unit 230 also controls, for example, communication with a node (e.g., a neighboring base station, the core network device 300) via the network communication unit 220. The operations of the base station 200 described above and below may be controlled by the control unit 230. The control unit 230 may include at least one processor capable of executing a program and a memory that stores the program. The processor may execute the program to perform the operations of the control unit 230. The control unit 230 may include a digital signal processor that performs digital processing of signals transmitted and received via the antenna and the RF circuit. The digital processing includes processing of a RAN protocol stack. The memory stores programs executed by the processor, parameters related to the programs, and data related to the programs. All or a part of the memory may be included in the processor.

[0034] (First Embodiment) A first embodiment will be described with reference to Figs. 5 to 7 . Currently, as one of the discussions on NES, introduction of an SIB1 (hereinafter, appropriately referred to as an on-demand SIB1) that is transmitted (e.g., broadcast) in response to a request from a UE 100 is being considered. In introducing the on-demand SIB1, multiple scenarios for a procedure for acquiring the on-demand SIB1 (hereinafter, appropriately referred to as an on-demand SIB1 acquisition procedure) are being discussed. Here, SIB1 may be used to specify the scheduling of other system information blocks (e.g., SIBX (X is a natural number equal to or greater than 2) other than SIB1). That is, SIB1 may include information regarding the scheduling of other system information blocks. SIB1 may also include information indicating the availability of other system information blocks. SIB1 may also include information indicating whether other system information blocks are provided only on-demand and / or configuration information for requesting transmission of other system information blocks. SIB1 may also include information required for initial access. Here, SIB1 is also referred to as Remaining Minimum System Information (RMSI). SIB1 may also be periodically transmitted on a Downlink Shared Channel (DL-SCH). Here, the DL-SCH is mapped to a Physical Downlink Shared Channel (PDSCH). That is, as described below, SIB1 may be transmitted on (or carried on) the PDSCH. For example, the default transmission period of SIB1 may be 20 ms. Here, SIB1 and / or other system information blocks other than SIB1 may be referred to as system information (system information message).

[0035] For example, there are listed scenarios in which UE 100 transmits information for requesting transmission of on-demand SIB1 to a cell supporting on-demand SIB1 (hereinafter, sometimes referred to as an NES cell), and a scenario in which UE 100 transmits information for requesting transmission of on-demand SIB1 to a cell different from the NES cell (hereinafter, sometimes referred to as cell A). There are also listed scenarios in which UE 100 receives on-demand SIB1 from the NES cell, and a scenario in which UE 100 receives on-demand SIB1 from cell A.

[0036] Here, when multiple scenarios are supported in the mobile communication system 1, it is not clear for which cell, the NES cell or cell A, the UE 100 should perform the on-demand SIB1 acquisition procedure. Therefore, for example, there is a concern that the network 10 cannot control the on-demand SIB1 acquisition procedure, causing a malfunction and preventing the UE 100 from properly acquiring the SIB1 of the NES cell. Therefore, one of the objectives of the present disclosure is to enable the UE 100 to properly acquire the SIB1 of the NES cell.

[0037] As shown in FIG. 5 , UE 100 is located within the coverage of cell C1 managed by base station 201 and can receive radio signals from cell C1. At the initial stage of FIG. 6 , UE 100 may be in an RRC idle state or an RRC inactive state with cell C1. Alternatively, UE 100 may be in an RRC connected state with cell C1. That is, in cell C1, the RRC state of UE 100 may be an RRC idle state, an RRC inactive state, or an RRC connected state. Cell C1 may be a cell on which UE 100 is camped. Alternatively, cell C1 may be a cell that UE 100 has (re)selected. Cell C1 may be a cell to which UE 100 has established an RRC connection. Cell C1 may be referred to as a serving cell.

[0038] Also, as shown in FIG. 5 , UE 100 may be located within the coverage of cell C2 managed by base station 202 and may be able to receive radio signals from cell C2. UE 100 may be in a state before (re)selecting cell C2, for example. Therefore, cell C2 may be a cell on which UE 100 is not camped. Alternatively, UE 100 may be in an RRC idle state or an RRC inactive state in cell C2. Alternatively, UE 100 may be in an RRC connected state in cell C2. Cell C2 may be a cell on which UE 100 is camped. Alternatively, cell C2 may be a cell that UE 100 has (re)selected. Cell C2 may be referred to as a serving cell.

[0039] In this embodiment, a case is given in which base station 201 manages cell C1 and base station 202 manages cell C2, but one base station 200 may manage both cell C1 and cell C2.

[0040] Cell C1 may be the first cell. The first cell may be at least one of (a1) a cell that always periodically broadcasts SIB1, (a2) a cell that (starts) transmitting SIB1 without a request from UE100, (a3) ​​a cell that does not support on-demand SIB1 (i.e., the on-demand SIB1 function), (a4) a cell that does not transmit on-demand SIB1, and (a5) a cell that transmits configuration information for acquiring (and / or requesting) on-demand SIB1. Furthermore, the first cell may be a serving cell for UE100 or a primary cell (i.e., P-cell) for UE100. The first cell may be cell A. The first cell may also be referred to as an anchor cell. That is, UE100 may receive configuration information for acquiring (and / or requesting) on-demand SIB1 from the first cell (e.g., base station 201 of the first cell). For example, UE 100 may receive configuration information for acquiring (and / or requesting) on-demand SIB1 from the first cell on which it is camped.

[0041] Cell C2 may be a second cell. The second cell may be at least one of (b1) a cell that temporarily broadcasts SIB1, (b2) a cell that transmits SIB1 in response to a request from UE 100, (b3) a cell that supports on-demand SIB1 (i.e., the on-demand SIB1 function), (b4) a cell that transmits on-demand SIB1, and (b5) a cell associated with configuration information for acquiring (and / or requesting) on-demand SIB1. The second cell may be an NES cell. The second cell may also be referred to as a non-anchor cell. That is, UE 100 may acquire on-demand SIB1 from a cell associated with configuration information for acquiring (and / or requesting) on-demand SIB1 (UL WUS configuration information, described later). UE 100 may also transmit information (i.e., UL WUS, described later) for requesting transmission of on-demand SIB1 to a cell associated with configuration information for acquiring (and / or requesting) on-demand SIB1. The information for requesting transmission of the on-demand SIB1 may be referred to as a request for the on-demand SIB1. Here, the cell associated with the configuration information for acquiring (and / or requesting) the on-demand SIB1 may be a cell to which the configuration information for acquiring (and / or requesting) the on-demand SIB1, described later, applies. For example, the UE 100 may identify the second cell based on information indicating a physical cell identifier (PCI) included in the configuration information for acquiring (and / or requesting) the on-demand SIB1. Furthermore, the UE 100 may identify the second cell based on information indicating a frequency (e.g., information indicating an absolute radio frequency channel number (ARFCN)) included in the configuration information for acquiring (and / or requesting) the on-demand SIB1. That is, UE100 may identify the cell (i.e., the second cell) from which to acquire (and / or request) on-demand SIB1 based on information indicating the PCI and / or information indicating the frequency included in the configuration information for acquiring (and / or requesting) on-demand SIB1.For example, the UE 100 may acquire the on-demand SIB1 from the second cell on which the UE 100 is camped. Furthermore, the UE 100 may transmit information for requesting transmission of the on-demand SIB1 to the second cell on which the UE 100 is camped. That is, the UE 100 may acquire the on-demand SIB1 from the (re)selected second cell. Furthermore, the UE 100 may transmit information for requesting transmission of the on-demand SIB1 to the (re)selected second cell. Here, the information for requesting transmission of the on-demand SIB1 (UL WUS, described later) may include a random access preamble. That is, the information for requesting transmission of the on-demand SIB1 may include a random access preamble (message 1) transmitted in a random access opportunity (e.g., time resources and / or frequency resources of a physical random access channel (PRACH)). Hereinafter, the transmission of the random access preamble (transmission of message 1) at the random access opportunity will also be simply referred to as the transmission of the PRACH.

[0042] In this specification, for UE 100, communication with a cell may be communication with a base station, and for UE 100, communication with a base station may be communication with a cell. For example, the base station may transmit information / messages, etc. to UE 100 from a certain cell (or in a certain cell). For UE 100, receiving information / messages, etc. from a cell may be receiving information / messages, etc. from the base station. Similarly, the base station may receive information / messages, etc. from UE 100 via a certain cell (or in a certain cell). For UE 100, transmitting information / messages, etc. to a cell may be transmitting information / messages, etc. to the base station.

[0043] Step S10: The transmitter 211 of the base station 202 transmits a master information block (MIB) from cell C2 to the UE 100. The receiver 112 of the UE 100 receives the MIB from cell C2. The MIB includes system information transmitted on a broadcast channel (BCH). The MIB may also be transmitted on a physical broadcast channel (PBCH). For example, the receiver 112 of the UE 100 may receive a synchronization signal and a PBCH block (SSB: Synchronization Signal / PBCH block) in cell C2 and receive the MIB on the PBCH of the SSB. Here, the UE 100 may select cell C2 by cell (re)selection. For example, the UE 100 may select cell C2 as a suitable cell based on SSB measurements and camp on the selected cell C2. Here, step S10 may be executed after step S20.

[0044] In this embodiment, the UE 100 may receive information for determining a target cell (hereinafter, target cell information) from cell C1 (base station 201 of cell C1) and / or cell C2 (base station 202 of cell C2). Here, the target cell may be a cell that is a target of the on-demand SIB1 acquisition procedure (and / or on-demand SIB1 request procedure). For example, the target cell may be at least one of a first cell and a second cell. That is, the target cell may be at least one of a cell (hereinafter, appropriately referred to as a first target cell) that is a transmission destination of an on-demand SIB1 request (information for requesting transmission of on-demand SIB1) and a cell (hereinafter, appropriately referred to as a second target cell) that acquires (receives) the on-demand SIB1. Here, the information for setting the first target cell is also referred to as first target cell information (or first information). Furthermore, the information for setting the second target cell is also referred to as second target cell information (or second information). That is, the target cell information may include first information and / or second information. For example, the first information may be used to set a cell (destination cell) from which the UE 100 transmits information for requesting transmission of the on-demand SIB1 (i.e., UL WUS, described later). Furthermore, the second information may be used to set a cell from which the UE 100 acquires the on-demand SIB1 (a source cell from which the on-demand SIB1 is transmitted). The UE 100 may determine (specify) a cell from which to transmit information for requesting transmission of the on-demand SIB1 based on the target cell information (e.g., the first information). Furthermore, the UE 100 may determine (specify) a cell from which to acquire the on-demand SIB1 based on the target cell information (e.g., the second information).

[0045] The target cell information may include information indicating the target cell. The target cell information may include, for example, information indicating a first target cell, i.e., a transmission destination of the request for on-demand SIB1. The target cell information may indicate, for example, whether the transmission destination is cell C2, i.e., whether the transmission destination is the first cell or the second cell. The target cell information may indicate the transmission destination with one bit (e.g., 0 / 1). Note that the information (or signal) for requesting transmission of on-demand SIB1 may be referred to as an uplink wake-up signal (UL WUS).

[0046] As described above, the target cell information may include, for example, information indicating the second target cell, i.e., the source of the on-demand SIB1. The target cell information may indicate, for example, whether the source is cell C2, i.e., whether the source is the first cell or the second cell. The target cell information may indicate the source with one bit (e.g., 0 / 1). That is, the target cell information may include information indicating the PCI of the target cell and / or information indicating the frequency of the target cell. For example, the first information may include information indicating the PCI of the first target cell and / or information indicating the frequency of the first target cell. Furthermore, the second information may include information indicating the PCI of the second target cell and / or information indicating the frequency of the second target cell. For example, when the first target cell is indicated by one-bit information, a value of "0" may correspond to the first cell, and a value of "1" may correspond to the second cell. Furthermore, when the second target cell is indicated by 1-bit information, a value of "0" may correspond to the first cell, and a value of "1" may correspond to the second cell. Furthermore, the first information may be information for setting the cell C1. That is, the first information may be information for setting the cell C1 as a cell from which the UE 100 transmits information for requesting transmission of the on-demand SIB1. Here, when the first information is not set, the UE 100 may determine the cell C2 as a cell from which the information for requesting transmission of the on-demand SIB1 is transmitted. Furthermore, the second information may be information for setting the cell C1. That is, the second information may be information for setting the cell C1 as a cell from which the UE 100 acquires the on-demand SIB1. Here, when the second information is not set, the UE 100 may determine the cell C2 as a cell from which the on-demand SIB1 is acquired. Here, the first information may be information for setting the cell C2, and when the second information is not set, the UE 100 may determine the cell C1 as the cell that transmits information for requesting transmission of the on-demand SIB1. Also, the second information may be information for setting the cell C2, and when the second information is not set, the UE 100 may determine the cell C1 as the cell that transmits information for requesting transmission of the on-demand SIB1.

[0047] The target cell information may include information indicating one cell as the first target cell and one cell as the second target cell. The target cell information may indicate, for example, whether cell C2 (i.e., the second cell) is a target cell (i.e., the first target cell and the second target cell). For example, the target cell information may include information indicating one PCI and / or information indicating one frequency, and the first target cell and the second target cell may be indicated using the information indicating one PCI and / or the information indicating one frequency. That is, the cell to which the information for requesting transmission of the on-demand SIB1 is to be transmitted and the cell from which the on-demand SIB1 is to be acquired may be determined using the information indicating one PCI and / or the information indicating one frequency. Here, the target cell information may be included in the MIB. That is, the target cell information may be included in the MIB transmitted from cell C2 (the base station 202 of cell C2) in step S10.

[0048] Step S20: The transmitter 211 of the base station 201 transmits, from the cell C1 to the UE 100, configuration information (hereinafter referred to as UL WUS configuration information (UL WUS config.)) for acquiring (and / or requesting) SIB1 of the cell C2 (i.e., on-demand SIB1) transmitted in response to a request from the UE 100. The receiver 112 of the UE 100 receives the UL WUS configuration information from the cell C1. That is, the UE 100 may receive the UL WUS configuration information in the cell C1 on which it is camped.

[0049] The transmitter 211 of the base station 201 may transmit the UL WUS configuration information, for example, by system information of the cell C1 (e.g., SIB1 and / or another SIB other than SIB1). Alternatively, the transmitter 211 may transmit the UL WUS configuration information by an individual RRC message that is individually transmitted to the UE 100. The transmitter 211 of the base station 201 may transmit, as an individual RRC message including the UL WUS configuration information, for example, an RRC release message used to command (instruct) the release of an RRC connection or the suspension of an RRC connection. That is, the transmitter 211 of the base station 201 may transmit system information including the UL WUS configuration information from the cell C1. Alternatively, the transmitter 211 of the base station 201 may transmit, from the cell C1, an RRC release message including the UL WUS configuration information. The UE 100 may receive system information including UL WUS setting information from the cell C1 (the base station 201 of the cell C1). Also, the UE 100 may receive an RRC release message including the UL WUS setting information from the cell C1 (the base station 201 of the cell C1).

[0050] The UL WUS configuration information may include target cell information. The target cell information may be information similar to the target cell information included in the above-mentioned MIB. Therefore, the target cell information may indicate, for example, whether the transmission destination is cell C1 or not, that is, whether the transmission destination is the first cell or the second cell. Furthermore, the target cell information may indicate whether the transmission destination is cell C1 or not, that is, whether the transmission destination is the first cell or the second cell. Alternatively, the target cell information may include information for setting cell C1 as the target cell. For example, when the UL WUS configuration information includes information for setting cell C1 as the target cell (i.e., the first target cell and / or the second target cell), the UE 100 may set cell C1 as the target cell. On the other hand, when the UL WUS configuration information does not include this information, the UE 100 may set cell C2 as the target cell. The target cell information may be information for setting cell C2 as the target cell. The UL WUS configuration information may include first information and / or second information.

[0051] The UL WUS configuration information may include information indicating a second cell to which the UL WUS configuration information is applied in order to acquire the on-demand SIB1. This information may include, for example, information indicating the PCI of the second cell and / or information indicating the frequency of the second cell (e.g., ARFCN: Absolute radio-frequency channel number). That is, the UL WUS configuration information may include information indicating a cell to which the UL WUS configuration information is applied. Here, the information indicating a cell to which the UL WUS configuration information is applied may correspond to the first information. That is, the first target cell configured using the first information may be a cell to which the UL WUS configuration information is applied. Furthermore, the cell to which the UL WUS configuration information is applied may be a cell associated with configuration information for acquiring (and / or requesting) the above-mentioned on-demand SIB1. For example, the UL WUS configuration information may include information indicating random access parameters related to the second cell (e.g., RACH-ConfigCommon). That is, the UL WUS configuration information may include information for configuring a random access opportunity (e.g., information for configuring a time resource and / or a frequency resource of the PRACH). Furthermore, the UL WUS configuration information may include information for configuring transmission of a random access preamble (e.g., information for configuring an index of the random access preamble and / or information for configuring power for transmitting the random access preamble). As described above, the UE 100 may transmit message 1 (random access preamble) in the random access procedure as a WUS. Here, the UL WUS configuration information may include information indicating an uplink bandwidth part (UL BWP) over which the UE 100 transmits the random access preamble. For example, the information indicating the UL BWP may include information indicating a position in the frequency domain and / or a bandwidth of the UL BWP, and may also include information indicating an index of the UL BWP.The UE 100 may transmit the UL WUS in the UL BWP indicated by using information indicating the UL BWP in a cell to which the UL WUS configuration information is applied. Here, the UL WUS configuration information may include information regarding an uplink carrier to which the UE 100 transmits the random access preamble. For example, the information regarding the uplink carrier may include information indicating a frequency (ARFCN) of the uplink carrier. That is, information regarding the frequency of the uplink carrier of the cell to which the UL WUS configuration information is applied may be indicated using the information regarding the uplink carrier.

[0052] Furthermore, the UL WUS configuration information may include information used to acquire the on-demand SIB1 (hereinafter referred to as on-demand SIB1 acquisition information). The on-demand SIB1 acquisition information may include information used to acquire the on-demand SIB1 for the first cell (hereinafter referred to as acquisition information for the first cell), or may include information used to acquire the on-demand SIB1 for the second cell (hereinafter referred to as acquisition information for the second cell). For example, the on-demand SIB1 acquisition information may include second information. Based on the second information, the UE 100 may determine which of the acquisition information for the first cell and the acquisition information for the second cell to use to acquire the on-demand SIB1. Furthermore, the on-demand SIB1 acquisition information may include information indicating control resource set #0 (CORESET #0) and / or information indicating search space set #0 (SearchSpace #0). The UE 100 may monitor a physical downlink control channel (PDCCH) in a control resource set (i.e., CORESET #0) indicated using information indicating the control resource set #0, and / or a search space set (i.e., SearchSpace #0) indicated using information indicating the search space set #0. Here, the PDCCH may be used to transmit downlink control information (DCI) for scheduling the PDSCH on which the on-demand SIB1 is transmitted. Furthermore, the DCI (which may be the PDCCH) may be added with a system information radio network temporary identifier (SI-RNTI). That is, the DCI (which may be the PDCCH) may be added with a cyclic redundancy check (CRC, which may be a CRC parity bit) scrambled by the SI-RNTI. For example, the acquisition information for the first cell may include information indicating CORESET #0 used to acquire the on-demand SIB1 in the first cell, and / or information indicating SearchSpace #0. In addition, the acquisition information for the second cell may include information indicating control resource set #0 used to acquire on-demand SIB1 in the second cell and / or information indicating search space set #0.

[0053] For example, when the acquisition information for the first cell is included in the system information of the cell C1, it may include information (e.g., SI-SchedulingInfo) necessary to acquire the system information (SI) message of the cell C1. For example, a specific SIB related to the on-demand SIB1 may be entered in the SI-SchedulingInfo as the acquisition information for the first cell. Furthermore, the acquisition information for the first cell may include information (e.g., si-RequestConfig) for transmitting a request for the on-demand SIB1 (i.e., UL WUS) to the cell C1, or may include information for receiving the on-demand SIB1 from the cell C1. Here, the si-RequestConfig may include information for setting a random access opportunity used for transmitting information (UL WUS) for requesting the transmission of the on-demand SIB1 to the cell C1. In addition, the information for receiving on-demand SIB1 from cell C1 may include information indicating control resource set #0 used to acquire on-demand SIB1 in the first cell and / or information indicating search space set #0.

[0054] The information for receiving the on-demand SIB1 from the cell C1 may include scheduling information (e.g., schedulingInfoList, si-BroadcastStatus, si-WindowLength, si-Periodicity, and / or si-WindowPosition, etc.) and may include information regarding the reception timing and / or time window of the on-demand SIB1. The information may be expressed, for example, by a system frame number (SFN), a subframe, a slot, or a symbol. Also, as described above, the information for receiving the on-demand SIB1 may include, for example, information for monitoring the PDCCH (e.g., information indicating CORESET #0 of the cell C1 and / or information indicating SearchSpace #0). Here, si-BroadcastStatus may include information indicating whether the on-demand SIB1 is being broadcast (transmitted) (whether the on-demand SIB1 has already been broadcast in the cell). Furthermore, si-WindowLength may include information indicating the length of the window for transmitting the on-demand SIB1. Furthermore, si-Periodicity may include information indicating the period for transmitting the on-demand SIB1. Furthermore, si-WindowPosition may include information indicating the position of the window for transmitting the on-demand SIB1. The UE 100 may acquire (receive) the on-demand SIB1 from the cell C1 based on the scheduling information, the reception timing, and / or information regarding the time window.

[0055] The acquisition information for the second cell may include information for transmitting a request for the on-demand SIB1 to the cell C2 (e.g., si-RequestConfig, information on a random access opportunity (RACH opportunity), and / or information on a preamble, etc.), and may include information for receiving the on-demand SIB1 from the cell C2. Similarly to the above, the information for receiving the on-demand SIB1 from the cell C2 may include scheduling information, information on the reception timing and / or time window of the on-demand SIB1, information for monitoring the PDCCH, etc. The UE 100 may acquire (receive) the on-demand SIB1 from the cell C2 based on the scheduling information, the reception timing, and / or the information on the time window.

[0056] The UL WUS configuration information may also include configuration information for receiving a random access response (message 2 in the random access procedure). As described below, for example, the UE 100 may determine whether the transmission of the random access preamble (message 1) has been successfully completed based on the reception of the random access response. That is, the UE 100 may determine whether the random access procedure has been successfully completed based on the reception of the random access response. For example, when the UE 100 receives the random access response, the UE 100 may consider that the request for the on-demand SIB1 has been successfully completed (that is, a positive response to the request for the on-demand SIB1 has been received). For example, the configuration information for receiving the random access response may include information indicating a period for receiving the random access response (random access response window), information indicating a control resource set used to monitor a DCI (which may be a PDCCH) to which a random access radio network temporary identifier (RA-RNTI) is attached, and / or information indicating a search space set. Here, the PDSCH to which the random access response is transmitted may be scheduled using DCI to which the RA-RNTI is attached. That is, the UE 100 may monitor DCI to which a CRC scrambled by the RA-RNTI is attached, and receive the random access response in the PDSCH scheduled using the DCI. Furthermore, the configuration information for receiving the random access response may include information indicating a time resource (for example, a slot and / or a symbol) for the UE 100 to monitor the DCI to which the RA-RNTI is attached.

[0057] Here, the UE 100 may determine whether to perform cell (re)selection for the cell C2. For example, the UE 100 may perform cell (re)selection for the cell C2 based on intra-frequency measurements (i.e., measurements of intra-frequency neighboring cells) and / or inter-frequency measurements (i.e., measurements of inter-frequency neighboring cells). That is, the cell (re)selection for the cell C2 may be intra-frequency cell (re)selection and / or inter-frequency cell (re)selection. Furthermore, the UE 100 may perform cell (re)selection for the cell C2 based on the fact that the cell C2 (the base station 202 of the cell C2) does not broadcast SIB1 (which may be on-demand SIB1) and / or supports on-demand SIB1.

[0058] For example, the UE 100 may determine whether the cell C2 broadcasts SIB1 (which may be on-demand SIB1) and / or supports on-demand SIB1 based on the closest RMSI opportunity. Furthermore, the UE 100 may determine whether the cell C2 broadcasts SIB1 (which may be on-demand SIB1) and / or supports on-demand SIB1 based on information included in an MIB transmitted in the cell C2. Here, the information included in the MIB may include information indicating the cell status and / or information indicating whether SIB1 (which may be on-demand SIB1) is provided. The information indicating the cell status may indicate that the cell is allowed (e.g., "allow," "allowed," "notBarred," etc.) or that the cell is barred (e.g., "bar," "barred," "notAllowed," etc.). For example, the UE 100 may determine that the cell C2 supports the on-demand SIB1 when the information indicating the cell status indicates that the cell is permitted. Furthermore, the UE 100 may determine that the cell C2 does not support the on-demand SIB1 when the information indicating the cell status indicates that the cell is prohibited. In another example, the UE 100 may determine that the cell C2 supports the on-demand SIB1 when the information indicating the cell status indicates that the cell is prohibited. Furthermore, the UE 100 may determine whether the cell C2 broadcasts the SIB1 (which may be the on-demand SIB1) and / or whether the cell C2 supports the on-demand SIB1 based on information indicating whether the SIB1 (which may be the on-demand SIB1) is provided.

[0059] Furthermore, the UE 100 may perform cell (re)selection for the cell C2 on the basis that the UE 100 has UL WUS setting information for the cell C2 (the UL WUS setting information is set).

[0060] The UE 100 determines to perform cell (re)selection for the cell C2, and when the cell C2 is (re)selected, the UE 100 may execute (trigger) transmission of information (UL WUS) for requesting transmission of the on-demand SIB1. That is, the UE 100 may execute (trigger) transmission of information (UL WUS) for requesting transmission of the on-demand SIB1 based on (re)selection of the cell C2 by cell (re)selection. Furthermore, when the UE 100 (re)selects the cell C2 by cell (re)selection, the UE 100 may execute (trigger) determination of a target cell (step S30) described later.

[0061] Step S30: The control unit 120 of the UE 100 determines a target cell. The control unit 120 may determine a first target cell as the target cell. The control unit 120 may determine both the first target cell and the second target cell as the target cells. Furthermore, for example, when the on-demand SIB1 of the cell C2 has already been broadcast in response to a request from another UE 100, the control unit 120 may determine a second target cell without determining a first target cell. In this case, the processes of steps S40 and S50 may be omitted. Details of the determination of the second target cell will be described in step S50.

[0062] The control unit 120 may determine the target cell based on the target cell information. For example, the control unit 120 may determine a first target cell, i.e., a cell indicated by information indicating a transmission destination of the on-demand SIB1 request, as the target cell. If the information (e.g., first information) indicates cell C1 (or the first cell), the control unit 120 may determine cell C1 as the target cell, and if the information (e.g., first information) indicates cell C2 (or the second cell), the control unit 120 may determine cell C2 as the target cell.

[0063] Furthermore, the target cell information may include on-demand SIB1 acquisition information. The control unit 120 may determine the target cell based on the on-demand SIB1 acquisition information as the target cell information. For example, when using information for transmitting a request for on-demand SIB1 to cell C1 (e.g., when the information is set), the control unit 120 may determine cell C1 as the first target cell. On the other hand, when using information for transmitting a request for on-demand SIB1 to cell C2 (e.g., when the information is set), the control unit 120 may determine cell C2 as the first target cell. For example, the control unit 120 may determine cell C1 as the first target cell for a random access opportunity for transmitting a request for on-demand SIB1 to cell C1. Furthermore, the control unit 120 may determine cell C2 as the first target cell for a random access opportunity for transmitting a request for on-demand SIB1 to cell C2. That is, the control unit 120 may determine the first target cell based on a random access opportunity used to transmit a random access preamble.

[0064] In addition, when the control unit 120 has both acquisition information for the first cell and acquisition information for the second cell (for example, both acquisition information are set), it may (i) preferentially use the acquisition information for the first cell, (ii) preferentially use the acquisition information for the second cell, or (iii) use the acquisition information corresponding to the target cell determined based on the target cell information indicating the target cell.

[0065] The control unit 120 executes an on-demand SIB1 acquisition procedure (and / or a request procedure) for the determined target cell. The control unit 120 may execute subsequent processes.

[0066] Step S40: The UE 100 transmits a request for on-demand SIB1, i.e., a UL WUS, to the determined target cell (i.e., cell C1 or cell C2). An example of a method for transmitting a request for on-demand SIB1 will be described with reference to Fig. 7. The following mainly describes the case where the first target cell is cell C2.

[0067] Step S411: The transmitter 111 of the UE 100 may transmit a message 1 (MSG1) for requesting an on-demand SIB1 to the target cell. The MSG1 may correspond to UL WUS. The transmitter 111 of the UE 100 may transmit the PRACH (message 1) using, for example, a random access opportunity and / or a random access preamble based on the above-described configuration information. That is, the transmitter 111 of the UE 100 may transmit the PRACH (message 1) based on information for transmitting a request for the on-demand SIB1 to the cell C2 and / or information indicating random access parameters for the second cell. The receiver 212 of the base station 202 receives the message 1 for requesting the on-demand SIB1 from the UE 100 in the cell C2.

[0068] Step S412: The transmitter 211 of the base station 202 transmits a physical downlink control channel (PDCCH) from the cell C2 to the UE 100. The receiver 112 of the UE 100 receives the PDCCH from the cell C2. The receiver 112 of the UE 100 may receive the PDCCH from the cell C2 based on the above-mentioned UL WUS setting information.

[0069] As described above, the PDCCH carries a CRC scrambled by the RA-RNTI. The PDCCH carries scheduling information (also referred to as a downlink assignment) indicating radio resource allocation in Message 2. That is, for example, resources for the PDSCH may be scheduled using the PDCCH with a CRC scrambled by the RA-RNTI. Here, Message 2 may include the PDCCH with a CRC scrambled by the RA-RNTI and the PDSCH scheduled by the PDCCH. Message 2 may also be referred to as a random access response (RAR).

[0070] The control unit 120 of the UE 100 monitors the PDCCH with the CRC scrambled by the RA-RNTI in the cell C2. If the control unit 120 successfully decodes (i.e., receives) the PDCCH, the control unit 120 may attempt to receive message 2 (PDSCH) based on the scheduling information carried by the PDCCH. For example, the control unit 120 of the UE 100 may monitor the PDCCH with the CRC scrambled by the RA-RNTI within the period (random access response window) corresponding to the transmission of the PRACH described above.

[0071] Step S413: The transmitter 211 of the base station 202 transmits the message 2 from the cell C2 to the UE 100. The receiver 112 of the UE 100 receives the message 2 from the cell C2. The receiver 112 of the UE 100 may receive the message 2 based on the UL WUS configuration information. That is, the receiver 112 of the UE 100 may receive the message 2 based on the configuration information for receiving a random access response. The message 2 may be a message for acknowledgment to the message 1.

[0072] For example, when the control unit 120 of the UE 100 receives the message 2, the control unit 120 may determine whether or not the message 2 (i.e., the random access response) includes specific information. The specific information may be, for example, a MAC sub-PDU including a random access preamble identifier (RAPID) corresponding to the random access preamble (i.e., the index of the random access preamble) transmitted as the request for the on-demand SIB1.

[0073] The control unit 120 may determine that reception of Message 2 is successful if Message 2 includes specific information. On the other hand, the control unit 120 may determine that reception of Message 2 is not successful if Message 2 does not include specific information. That is, the control unit 120 may determine that reception of Message 2 is successful if Message 2 (i.e., the random access response) includes a MAC sub-PDU including a RAPID corresponding to the transmitted random access preamble (i.e., the index of the random access preamble). Furthermore, when the control unit 120 determines that reception of Message 2 is successful, it may determine that the random access procedure is successfully completed if Message 2 (i.e., the random access response) includes a MAC sub-PDU including only the RAPID. That is, the control unit 120 (e.g., the MAC layer) may instruct an upper layer (e.g., the RRC layer) that it has received an acknowledgment message for Message 1. Furthermore, the control unit 120 (for example, the MAC layer) may notify the PHY layer that a message for acknowledging the receipt of the message 1 has been received.

[0074] The RAR may include target cell information. The target cell information may include target cell information indicating a second target cell. The target cell information may include, for example, a RAPID. The target cell information may also include information used to receive the on-demand SIB1.

[0075] Step S50: The control unit 120 of the UE 100 may determine a target cell (specifically, a second target cell). The control unit 120 may determine, for example, the second target cell, i.e., the cell indicated by information indicating the source of the on-demand SIB1, as the target cell. If the information indicates cell C1 (or the first cell), the control unit 120 may determine cell C1 as the target cell, and if the information indicates cell C2 (or the second cell), the control unit 120 may determine cell C2 as the target cell.

[0076] Furthermore, when using information for receiving on-demand SIB1 from cell C1 (for example, when the information is set), control unit 120 may determine cell C1 as the second target cell. On the other hand, when using information for receiving on-demand SIB1 from cell C2 (for example, when the information is set), control unit 120 may determine cell C2 as the second target cell.

[0077] Furthermore, the control unit 120 may determine the cell that transmitted the request for on-demand SIB1 as the target cell. Thus, when the control unit 120 transmitted the request for on-demand SIB1 to cell C1, the control unit 120 may determine cell C1 as the second target cell, and when the control unit 120 transmitted the request for on-demand SIB1 to cell C2, the control unit 120 may determine cell C2 as the second target cell.

[0078] Furthermore, when the RAR includes target cell information, the control unit 120 may determine the second target cell based on the target cell information included in the RAR. The control unit 120 may determine the second target cell by prioritizing the target cell information included in the RAR over, for example, the target cell information included in the UL WUS setting information.

[0079] Step S60: The UE 100 receives the on-demand SIB1 from the determined second target cell (i.e., cell C1 or cell C2). An example of a method for receiving the on-demand SIB1 will be described below using FIG. 7. The case where the second target cell is cell C2 will be mainly described as an example.

[0080] Step S611: The transmitter 211 of the base station 202 transmits the PDCCH from the cell C2 to the UE 100. The receiver 112 of the UE 100 receives the PDCCH from the cell C2.

[0081] As mentioned above, the PDCCH carries a CRC scrambled by the SI-RNTI. The PDCCH carries scheduling information indicating the radio resource allocation for the SI message.

[0082] The control unit 120 of the UE 100 monitors the PDCCH with the CRC scrambled by the SI-RNTI. For example, the control unit 120 (e.g., the PHY layer) of the UE 100 may start monitoring the PDCCH with the CRC scrambled by the SI-RNTI based on an indication of reception of an acknowledgment message for message 1 from the MAC layer. The control unit 120 may determine a control resource set #0 (CORESET #0) and a search space #0 (SS #0) for monitoring downlink control information (DCI) dedicated to SIB1 (e.g., dedicated to on-demand SIB1) based on the UL WUS configuration information. The control unit 120 may determine the CORESET #0 and / or the search space #0 for the PDCCH with the CRC scrambled by the SI-RNTI based on the UL WUS configuration information. Alternatively, the control unit 120 may determine CORESET #0 and / or search space #0 based on the SSB (specifically, the MIB) of cell C2. The control unit 120 may monitor the PDCCH based on the determined control resource set #0 and search space #0. If the control unit 120 successfully decodes the PDCCH with a CRC scrambled by the SI-RNTI, the control unit 120 may attempt to receive an SI message (e.g., on-demand SIB1) based on the scheduling information carried by the PDCCH. Here, if the control unit 120 of the UE 100 is unable to acquire (receive) the on-demand SIB1, the control unit 120 may consider the cell (cell state) to be barred (bar). For example, the cell state may be defined as allowed or barred (bar). Here, the cell state being allowed is the same as the cell state being not barred (barred). For example, when the control unit 120 of the UE 100 cannot acquire the on-demand SIB 1 in response to transmission of information for requesting transmission of the on-demand SIB 1, the control unit 120 of the UE 100 may consider the state of the cell that transmitted the information for requesting transmission of the on-demand SIB 1 (the destination cell) to be barred (bar). When the control unit 120 of the UE 100 considers the state of the cell to be barred (bar), the control unit 120 may not perform cell (re)selection for the cell.For example, when the control unit 120 of the UE 100 considers that the state of a cell is barred (bar), the control unit 120 of the UE 100 may exclude the cell from candidates for cell (re)selection. For example, the control unit 120 of the UE 100 may exclude the cell from candidates for cell (re)selection for a predetermined period (for example, up to 300 seconds).

[0083] Step S612: The transmitter 211 of the base station 202 transmits the on-demand SIB1 from the cell C2 to the UE 100. The receiver 112 of the UE 100 receives the on-demand SIB1 from the cell C2. The on-demand SIB1 may be included in an SI message. Note that the SIB1 (SI message) may be carried by the Physical Downlink Shared Channel (PDSCH).

[0084] As described above, the transmitter 211 of the base station 201 may transmit, to the UE 100, UL WUS configuration information for acquiring (and / or requesting) the on-demand SIB1, which is the system information block type 1 of the second cell, transmitted from the cell C1 in response to a request from the UE 100. The transmitter 211 of the base station 201 and / or the base station 202 may transmit, to the UE 100, target cell information for determining the target cell when the UE 100 executes, for a target cell that is at least one of the cells C1 and C2, an on-demand SIB1 acquisition procedure for acquiring the on-demand SIB1 of the second cell based on the UL WUS configuration information. The receiver 112 of the UE 100 may receive, from the cell C1, UL WUS configuration information for acquiring the on-demand SIB1 of the cell C2. The control unit 120 may execute, for the target cell, an on-demand SIB1 acquisition procedure for acquiring the on-demand SIB1 based on the UL WUS configuration information. The control unit 120 may determine the target cell based on the target cell information. This allows the network 10 to control the determination of the target cell. As a result, the UE 100 can appropriately acquire the SIB1 of the cell C2.

[0085] Furthermore, the control unit 120 may determine the target cell based on the target cell information. The transmission unit 111 may transmit a request for the on-demand SIB1 to the determined target cell in the on-demand SIB1 acquisition procedure. This allows the network 10 to control the transmission destination of the request for the on-demand SIB1.

[0086] Furthermore, the target cell information may include information indicating a transmission destination of the request for the on-demand SIB1. The control unit 120 may determine the cell indicated by the information indicating the transmission destination as the target cell. This allows the UE 100 to explicitly know the transmission destination of the request for the on-demand SIB1.

[0087] Furthermore, the target cell information may include information for transmitting a request for on-demand SIB1. When using information for transmitting a request for on-demand SIB1 to a first cell, the control unit 120 may determine the first cell as the target cell. When using information for transmitting a request for on-demand SIB1 to a second cell, the control unit 120 may determine the second cell as the target cell. This allows the UE 100 to determine the target cell based on the information used to transmit the request for on-demand SIB1, even if the destination of the request for on-demand SIB1 is not explicitly indicated.

[0088] Furthermore, the control unit 120 may determine the target cell based on the target cell information. The receiving unit 112 may receive the on-demand SIB1 from the determined target cell in the on-demand SIB1 acquisition procedure. This allows the network 10 to control the destination of the on-demand SIB1 request.

[0089] Furthermore, the target cell information may include information indicating a transmission source of the on-demand SIB1. The control unit 120 may determine the cell indicated by the information indicating the transmission source as the target cell. This allows the UE 100 to explicitly grasp the transmission source of the on-demand SIB1.

[0090] Furthermore, the target cell information may include information for receiving the on-demand SIB1. When the control unit 120 uses information for receiving the on-demand SIB1 for the first cell, the control unit 120 may determine the first cell as the target cell. When the control unit 120 uses information for receiving the on-demand SIB1 for the second cell, the control unit 120 may determine the second cell as the target cell. This allows the UE 100 to determine the cell as the target cell based on the information used to receive the on-demand SIB1, even if the transmission source of the on-demand SIB1 is not explicitly indicated.

[0091] Furthermore, in the on-demand SIB1 acquisition procedure, the transmitter 111 may transmit a request for the on-demand SIB1 to the first cell or the second cell. The controller 120 may determine the cell that transmitted the request for the on-demand SIB1 as the target cell. This allows the UE 100 to explicitly grasp the source of the on-demand SIB1.

[0092] (First Modification of First Embodiment) A first modification of the first embodiment will be described with reference to Figs. 6 and 8. Previously described descriptions may be omitted. In this modification, a request for on-demand SIB1 is made by message 3. An example of a method for transmitting a request for on-demand SIB1 and a method for receiving on-demand SIB1 will be described below. The following mainly describes the case where the first target cell is cell C2.

[0093] Step S321: The transmitter 111 of the UE 100 transmits the message 1 to the cell C2. The receiver 212 of the base station 200 receives the message 1 from the UE 100 in the cell C2. The transmitter 111 may transmit the message 1 to the cell C2 based on the UL WUS setting information. For example, the transmitter 111 may transmit the message 1 to the cell C2 based on information indicating the random access parameters for the cell C2 included in the UL WUS setting information.

[0094] Step S322: The transmitter 211 of the base station 200 transmits the message 2 from the cell C2 to the UE 100. The receiver 112 of the UE 100 receives the message 2 from the cell C2.

[0095] Step S323: The transmitter 111 of the UE 100 transmits the on-demand SIB1 request message 3 to the cell C2. The receiver 212 of the base station 200 receives the on-demand SIB1 request message 3 from the UE 100 in the cell C2.

[0096] Message 3 may be a message (e.g., an RRCSystemInfoRequest message) used by UE 100 to request an SI message. Message 3 may also be used to request another SIB other than (on-demand) SIB1. The other SIB may be one or more SIBs subsequent to SIB1. Message 3 may be a message that requests on-demand SIB1 and another SIB together.

[0097] Step S324: The transmitter 211 of the base station 200 transmits the message 4 from the cell C2 to the UE 100. The receiver 112 of the UE 100 receives the message 4 from the cell C2.

[0098] Message 4 may be an acknowledgment message to message 3 .

[0099] Steps S621 and S622 correspond to steps S611 and S612. If the receiving unit 112 of the UE 100 has requested another SIB, the receiving unit 112 may receive an SI message including the other SIB in addition to the SI message including the on-demand SIB 1. The UE 100 may receive an SI message including the on-demand SIB 1 and the other SIB.

[0100] (Second Modification of First Embodiment) A second modification of the first embodiment will be described with reference to FIG. 9. Previous descriptions may be omitted. In this modification, the UE 100 determines a target cell based on the camped cell. The control unit 120 of the UE 100 may perform this operation in at least one of the above steps S30 and S50.

[0101] Step S710: The control unit 120 of the UE 100 may determine whether the UE 100 is camped on cell C2. If the UE 100 is camped on cell C2 (i.e., the second cell), the control unit 120 executes the process of step S720. On the other hand, if the UE 100 is not camped on cell C2, the control unit 120 executes the process of step S730.

[0102] Step S720: The control unit 120 determines the cell C2 as a target cell (i.e., the first target cell and / or the second target cell). That is, when the UE 100 is camped on the cell C2, the control unit 120 may ignore the target cell information and determine the target cell to be the cell C2.

[0103] Step S730: The control unit 120 may determine the target cell based on the target cell information (see steps S30 and S50). Alternatively, the control unit 120 may determine the camped cell C1 as the target cell.

[0104] As described above, when the UE 100 is camped on the cell C2, the control unit 120 may determine the cell C2 as the target cell regardless of the target cell information. As a result, after the UE 100 camps on the second cell, the UE 100 does not need to determine again which cell is the target cell each time it is necessary to perform the on-demand SIB1 acquisition procedure, and the processing load of the UE 100 can be reduced.

[0105] Second Embodiment A second embodiment will be described with reference to Fig. 10. Previous descriptions may be omitted. In this embodiment, a method for determining the validity of SIB1 stored in the UE 100 will be mainly described.

[0106] When the on-demand SIB1 is introduced in the mobile communication system 1, there is a concern that the UE 100 may not be able to properly determine the validity of the SIB1 and may not be able to properly acquire the SIB1 of the NES cell. Therefore, one of the objectives of the present disclosure is to enable the UE 100 to properly acquire the SIB1 of the NES cell.

[0107] In FIG. 10, the state of UE 100 may be the same as in the first embodiment.

[0108] Step S811: The transmitter 211 of the base station 201 transmits UL WUS configuration information from the cell C1 to the UE 100. The receiver 112 of the UE 100 receives the UL WUS configuration information from the cell C1. Alternatively, the transmitter 211 of the base station 201 may transmit the UL WUS configuration information from the cell C2 to the UE 100. The receiver 112 of the UE 100 may receive the UL WUS configuration information from the cell C2.

[0109] The UL WUS configuration information may include the same information as in the first embodiment. The UL WUS configuration information may include validity information (third information) for determining the validity of the on-demand SIB1. As a result, the receiving unit 112 of the UE 100 receives the validity information.

[0110] The validity information may include at least one of parameter information for identifying the version of the on-demand SIB1 (e.g., valueTag), a Public Land Mobile Network (PLMN) identifier (e.g., PLMN-Identity), a cell identifier (e.g., cellIdentity), information indicating whether the on-demand SIB1 is area-specific or cell-specific (e.g., areaScope), and an area identifier indicating the area to which the cell belongs (e.g., systemInformationAreaID). Here, the cell identifier may be information indicating the PCI.

[0111] Step S812: The control unit 120 of the UE 100 stores the validity information.

[0112] Steps S813 and S814 correspond to steps S40 and S60. As a result, the UE 100 acquires the on-demand SIB 1. Note that, although the UE 100 executes the on-demand SIB 1 acquisition procedure for the cell C2 in FIG. 10 , the UE 100 may execute the on-demand SIB 1 acquisition procedure for the cell C1.

[0113] Step S815: The control unit 120 of the UE 100 stores the SIB1. The control unit 120 associates the SIB1 with the validity information and stores them.

[0114] Step S816: As in step S811, the transmission unit 211 of the base station 201 transmits UL WUS configuration information from the cell C1 to the UE 100. The reception unit 112 of the UE 100 receives the UL WUS configuration information from the cell C1. For example, the reception unit 112 of the UE 100 may receive the UL WUS configuration information from a serving cell. That is, the reception unit 112 of the UE 100 may receive the UL WUS configuration information from a camped cell. As a result, the reception unit 112 of the UE 100 receives the latest UL WUS configuration information from the cell C1 for acquiring the latest on-demand SIB1 of the second cell. The latest UL WUS configuration information includes the latest validity information. That is, the reception unit 112 of the UE 100 may receive the UL WUS configuration information from the cell C1 for acquiring the on-demand SIB1 transmitted in the second cell. For example, the on-demand SIB1 transmitted in the second cell may be the on-demand SIB1 currently transmitted in the second cell. That is, the UL WUS configuration information may be configuration information for acquiring the on-demand SIB1 currently transmitted in the second cell. That is, the UL WUS configuration information may include validity information of the on-demand SIB1 currently transmitted in the second cell. Hereinafter, the latest validity information may include the meaning of the current validity information and may simply be referred to as validity information (received validity information). That is, the latest validity information may be replaced with the validity information (received validity information).

[0115] The control unit 120 may receive the UL WUS setting information when executing the process of step S817. Alternatively, the control unit 120 may execute the process of step S817 when the control unit 120 receives the UL WUS setting information.

[0116] The control unit 120 may execute the process of step S817 when performing cell reselection for cell C2. Furthermore, the control unit 120 may execute the process of step S817 at least at the time of cell selection (for example, when selecting a cell with power on), when returning from outside the coverage of cell C2, or after resetting due to completion of synchronization. Furthermore, the control unit 120 may execute the process of step S817 when using on-demand SIB1.

[0117] If the control unit 120 does not store the on-demand SIB1, the control unit 120 may omit the process of step S817. Therefore, the control unit 120 may start the procedure for acquiring the on-demand SIB1.

[0118] Step S817: The control unit 120 of the UE 100 determines the validity of the on-demand SIB1 based on the validity information. For example, the control unit 120 of the UE 100 may determine the validity of the on-demand SIB1 of the acquired cell C2 based on the validity information. Furthermore, the control unit 120 may determine the validity of the stored on-demand SIB1 based on the latest validity information and the stored validity information.

[0119] The control unit 120 determines whether the latest validity information and the stored validity information are the same. The control unit 120 may, for example, determine whether parameter information included in the latest validity information is the same as parameter information included in the stored validity information. For example, the control unit 120 may determine whether a PLMN identifier included in the latest validity information is the same as a PLMN identifier included in the stored validity information. Furthermore, the control unit 120 may determine whether a cell identifier included in the latest validity information is the same as a cell identifier included in the stored validity information.

[0120] Here, as a first identity determination method, the control unit 120 may determine (or may regard) the stored on-demand SIB1 as valid if it determines that the latest validity information and the stored validity information are identical for at least one of the multiple pieces of information including the parameter information, the PLMN identifier, and the cell identifier. On the other hand, the control unit 120 may determine (or may regard) the stored on-demand SIB1 as invalid if it determines that the latest validity information and the stored validity information are not identical for all of the multiple pieces of information used for the determination.

[0121] Alternatively, as a second method of determining whether the on-demand SIB1 is valid, the control unit 120 may determine (or consider) that the stored on-demand SIB1 is valid if it determines that the latest validity information and the stored validity information are identical for all of the pieces of information used in the determination. On the other hand, the control unit 120 may determine (or consider) that the stored on-demand SIB1 is invalid if it determines that the latest validity information and the stored validity information are not identical for at least one piece of information.

[0122] Furthermore, when the validity information includes information indicating whether the on-demand SIB1 is area-specific or cell-specific (hereinafter referred to as scope information), the control unit 120 may change (determine) the method for determining the validity of the on-demand SIB1 depending on whether the on-demand SIB1 is area-specific or cell-specific. Here, the scope information is referred to as information indicating area scope. The scope information may also be information indicating that the on-demand SIB1 is area-specific. That is, when the UL WUS configuration information includes scope information (when the WUS configuration information includes scope information), the on-demand SIB1 may be indicated as area-specific. Furthermore, when the UL WUS configuration information includes scope information (when the WUS configuration information does not include scope information), the on-demand SIB1 may be indicated as cell-specific.

[0123] The control unit 120 may determine that the on-demand SIB1 is area-specific if the scope information associated with the stored on-demand SIB1 indicates that the on-demand SIB1 is area-specific. On the other hand, the control unit 120 may determine that the on-demand SIB1 is cell-specific if the scope information indicates that the on-demand SIB1 is cell-specific. Alternatively, the control unit 120 may determine that the on-demand SIB1 is cell-specific if the control unit 120 does not store (or does not exist) scope information associated with the on-demand SIB1.

[0124] If the on-demand SIB1 is cell-specific, the control unit 120 may perform the same determination as described above. That is, if the on-demand SIB1 is cell-specific, the control unit 120 may determine whether the on-demand SIB1 is valid using the first identity determination method and / or the second identity determination method. On the other hand, if the on-demand SIB1 is area-specific, the control unit 120 may perform the determination for each of the parameter information and the PLMN identifier as described above. In addition, if the on-demand SIB1 is area-specific, the control unit 120 may determine whether the area identifier included in the latest validity information is identical to the area identifier included in the stored validity information. If the on-demand SIB1 is area-specific, the control unit 120 may perform the determination for multiple pieces of information including the parameter information, the PLMN identifier, and the area identifier as described above using the first identity determination method or the second identity determination method. Here, the area identifier may be information indicating the area of ​​the on-demand SIB1 belonging to the cell. That is, if the on-demand SIB1 is area-specific, the on-demand SIB1 may belong to the area identifier (ie, may be transmitted in the area indicated by the area identifier).

[0125] If the control unit 120 determines (or deems) that the stored on-demand SIB1 is invalid, the control unit 120 may execute the process of step S818. If the control unit 120 determines (or deems) that the stored on-demand SIB1 is invalid, the control unit 120 may delete the stored on-demand SIB1. On the other hand, if the control unit 120 determines (or deems) that the stored on-demand SIB1 is valid, the control unit 120 may omit the following process. Therefore, if the control unit 120 determines (or deems) that the stored on-demand SIB1 is valid, the control unit 120 may use the stored on-demand SIB1 without starting the on-demand SIB1 acquisition procedure. The control unit 120 may delete the stored on-demand SIB1 three hours after determining the validity of the stored on-demand SIB1.

[0126] Steps S818 and S819: Corresponding to steps S40 and S60. The control unit 120 of the UE 100 may start an on-demand SIB1 acquisition procedure for the cell C2 using the latest UL WUS configuration information.

[0127] As described above, the base station 201 may transmit, from the cell C1, to the UE 100, UL WUS configuration information and validity information for acquiring the on-demand SIB1 of the cell C2. The receiving unit 112 of the UE 100 may receive the UL WUS configuration information and the validity information from the cell C1. The control unit 120 may determine the validity of the on-demand SIB1 acquired based on the UL WUS configuration information, based on the validity information. As a result, the UE 100 can receive the validity information from the cell C1 that transmits the UL WUS configuration information. Therefore, for example, if the UE 100 stores a valid on-demand SIB1, the cell C2 does not need to transmit the SIB1, thereby enabling power saving of the cell C2.

[0128] Furthermore, the control unit 120 may store the on-demand SIB1 and the validity information. The receiving unit 112 may receive the latest validity information from the cell C1. The control unit 120 may determine the validity of the stored on-demand SIB1 based on the latest validity information and the stored validity information. This allows the UE 100 to appropriately determine the validity of the stored on-demand SIB1 by making a determination based on the latest validity information.

[0129] Furthermore, the receiving unit 112 may receive from the cell C1 the latest configuration information for acquiring the latest on-demand SIB1 of the cell C2. The latest configuration information may include the latest validity information. As a result, even if the stored on-demand SIB1 is not valid, the UE 100 has the latest configuration information, and therefore, can transmit a request for the on-demand SIB1 based on the latest configuration information.

[0130] The validity information includes at least one of parameter information for identifying a version of the on-demand SIB1, a PLMN identifier, a cell identifier, information indicating whether the on-demand SIB1 is area-specific or cell-specific, and an area identifier indicating the area to which the cell belongs. This allows the UE 100 to flexibly determine the validity of the on-demand SIB1 based on multiple types of information.

[0131] The validity information may also include information indicating whether the on-demand SIB1 is area-specific or cell-specific. The control unit 120 may change the method for determining the validity of the on-demand SIB1 depending on whether the on-demand SIB1 is area-specific or cell-specific. This allows the validity range of the on-demand SIB1 to be flexibly changed depending on whether the on-demand SIB1 is area-specific or cell-specific.

[0132] Furthermore, when performing cell reselection to cell C2, the control unit 120 may determine the validity of the stored on-demand SIB1. As a result, when the UE 100 stores a valid on-demand SIB1, the UE 100 can perform reselection to cell C2 using the stored valid on-demand SIB1 without performing a process of requesting the on-demand SIB1 from cell C2 or receiving the on-demand SIB1. As a result, power saving of the UE 100 can be achieved. Furthermore, since cell C2 does not need to transmit SIB1, power saving of cell C2 can also be achieved.

[0133] Furthermore, if the stored on-demand SIB1 is not valid, the control unit 120 may start a procedure to acquire the latest on-demand SIB1 of the cell C2. If the stored on-demand SIB1 is valid, the control unit 120 may use the stored on-demand SIB1 without starting the on-demand SIB1 acquisition procedure. This allows the UE 100 to avoid requesting the on-demand SIB1 even if it has a valid on-demand SIB1, thereby enabling power saving in the cell C2.

[0134] (First Modification of Second Embodiment) A first modification of the second embodiment will be described with reference to Fig. 11. Previous descriptions may be omitted. In this modification, a case will be described in which validity information is included in SIB1.

[0135] Step S831: In the cell C1, the transmission unit 211 of the base station 201 transmits the SIB1 of the cell C1 to the UE 100. The reception unit 112 of the UE 100 receives the SIB1 from the cell C1.

[0136] SIB1 may include scheduling information (e.g., SchedulingInfo) of a specific SIB (hereinafter referred to as SIBX as appropriate) including UL WUS configuration information. SIB1 may also include validity information of the SIBX. The validity information is information for determining the validity of the SIBX. The validity information may include at least one of parameter information (e.g., valueTag) for identifying a version of the specific SIB, a PLMN identifier (e.g., PLMN-Identity), a cell identifier (e.g., cellIdenity), scope information (e.g., areaScope), and an area identifier (e.g., systemInformationAreaID). Here, the cell identifier may be information indicating a PCI.

[0137] Step S832: The transmitter 111 of the UE 100 may transmit an SI request message to request SIBX to the cell C1. The receiver 212 of the base station 201 may receive the SI request message in the cell C1.

[0138] Step S833: In cell C1, the transmitter 211 of the base station 201 transmits a SIBX including the UL WUS setting information to the UE 100. The transmitter 211 of the base station 201 may transmit the SIBX based on the SI request message. The receiver 112 of the UE 100 receives the SIBX including the UL WUS setting information.

[0139] Step S834: The control unit 120 of the UE 100 stores the validity information of the SIBX. The control unit 120 may store the SIBX and the validity information in association with each other.

[0140] Steps S835 and S836: correspond to steps S40 and S60.

[0141] Step S837: The control unit 120 of the UE 100 stores the SIB1 of the cell C2. The control unit 120 associates the SIB1 of the cell C2 with validity information and stores the SIB1. The validity information may be validity information stored in association with the SIBX of the cell C1.

[0142] Step S838: As in step S831, the transmitting unit 211 of the base station 201 transmits the SIB1 of the cell C1 from the cell C1 to the UE 100. The receiving unit 112 of the UE 100 receives the SIB1 of the cell C1 from the cell C1. As a result, the receiving unit 112 of the UE 100 receives the latest SIB1 of the second cell from the cell C1. The latest SIB1 includes the latest validity information of the SIBX.

[0143] The control unit 120 may receive the SIB1 of the cell C1. When the control unit 120 determines to perform reselection to the cell C2, the control unit 120 may receive the SIB1 of the cell C1. When the SIB acquisition procedure is triggered, the control unit 120 may receive the SIB1 of the cell C1. The control unit 120 may perform the following process based on receiving the SIB1 of the cell C1. Furthermore, the control unit 120 may perform the following process based on performing reselection to the cell C2 after receiving the SIB1 of the cell C1, for example. Note that, when the control unit 120 already has a valid SIB1 of the cell C1, the control unit 120 may perform the following process without newly performing the process of step S838.

[0144] Step S839: The control unit 120 of the UE 100 determines the validity of the SIBX based on the validity information. The control unit 120 determines the validity of the stored SIBX based on the latest validity information and the stored validity information. The control unit 120 may make the determination in the same manner as in step S817.

[0145] If the control unit 120 determines that the stored SIBX is valid, it may determine (or may consider) that the on-demand SIB1 acquired and stored based on the UL WUS setting information included in the SIBX is valid. On the other hand, if the control unit 120 determines that the stored SIBX is invalid, it may determine (or may consider) that the on-demand SIB1 acquired and stored based on the UL WUS setting information included in the SIBX is invalid.

[0146] If the control unit 120 determines (or considers) that the stored on-demand SIB1 is invalid, the control unit 120 may execute the process of step S840 or S841. The control unit 120 may delete the stored on-demand SIB1. On the other hand, if the control unit 120 determines (or considers) that the stored on-demand SIB1 is valid, the control unit 120 may omit the following process.

[0147] Steps S840 to S843: correspond to steps S832, S833, S835, and S836. Note that the UE 100 may execute the processes of steps S834 and S837.

[0148] As described above, the receiving unit 112 of the UE 100 may receive an SIBX including UL WUS configuration information from the cell C1. The receiving unit 112 of the UE 100 may receive information for determining the validity of a specific SIB as the latest validity information, via the system information block type 1 of the first cell. The control unit 120 may determine the validity of the stored on-demand SIB1 based on the validity of the specific SIB. This allows the validity of the on-demand SIB1 to be determined by extending the existing method for determining the validity of an SIB, thereby reducing the impact on the mobile communication system 1.

[0149] (Second Modification of Second Embodiment) A second modification of the second embodiment will be described with reference to Fig. 12. Previous descriptions may be omitted. In this modification, a case will be described in which validity information is included in the MIB.

[0150] Step S851: The transmitting unit 211 of the base station 202 transmits the MIB from the cell C2 to the UE 100. The receiving unit 112 of the UE 100 receives the MIB from the cell C2. The MIB includes validity information of the SIB1.

[0151] The validity information includes at least one of parameter information for identifying the version of on-demand SIB1, a PLMN identifier, a cell identifier, information indicating whether on-demand SIB1 is area-specific or cell-specific, and an area identifier indicating the area to which the cell belongs.

[0152] Step S852: corresponds to step S812.

[0153] Step S853: Corresponds to step S811. However, the UL WUS setting information does not need to include validity information.

[0154] Steps S854 to S856: Corresponding to steps S813 to S815. That is, the control unit 120 of the UE 100 associates the SIB1 with the validity information related to the SIB1 acquired from the MIB and stores the SIB1.

[0155] Step S857: As in step S851, the transmitter 211 of the base station 201 transmits the MIB from the cell C2 to the UE 100. The receiver 112 of the UE 100 receives the MIB from the cell C2. The MIB includes validity information of the SIB1. As a result, the receiver 112 of the UE 100 receives the latest configuration information for acquiring the latest on-demand SIB1 of the second cell from the cell C2. The latest configuration information includes the latest validity information.

[0156] Step S858: corresponds to step S817.

[0157] Steps S859 to S861: correspond to steps S853 to S855.

[0158] Third Embodiment A third embodiment will be described with reference to Fig. 13. Previously described descriptions may be omitted.

[0159] Currently, in the mobile communication system 1, when the UE 100 receives a short message, the UE 100 may start a procedure for reacquiring the periodically broadcasted SIB1. However, when the on-demand SIB1 is introduced, the SIB is not periodically broadcast in the second cell, so it is unclear what action the UE 100 will take when it receives a short message. For this reason, there is a concern that the UE 100 may not be able to properly acquire the SIB1 of the second cell. Therefore, one of the objectives of the present disclosure is to enable the UE 100 to properly acquire the SIB1 of the NES cell.

[0160] At the beginning of FIG. 13 , UE 100 is located within the coverage of cell C2 managed by base station 202 and can receive radio signals from cell C2. UE 100 may be in an RRC idle state or an RRC inactive state in cell C2. Alternatively, UE 100 may be in an RRC connected state in cell C2. That is, the RRC state of UE 100 may be an RRC idle state, an RRC inactive state, or an RRC connected state. Cell C2 may be a cell on which UE 100 is camped or a cell that UE 100 has (re)selected. Cell C2 may be a cell to which UE 100 has established an RRC connection. Cell C2 may be referred to as a serving cell.

[0161] Step S911: The transmitter 211 of the base station 202 transmits a short message including bit information from the cell C2 to the UE 100. The transmitter 211 may transmit the short message via downlink control information (DCI) on a PDCCH with a CRC scrambled by a paging network temporary identifier (P-RNTI).

[0162] In this embodiment, the bit information may include, for example, an indication of a change to a broadcast channel (BCCH) other than SIB6, SIB7, SIB8, and posSIB (e.g., a system information modification (systemInfoModification) bit). When SIBs other than SIB6, SIB7, SIB8, and posSIB are to be changed from the next modification period (Modification Period: MP), the control unit 230 of the base station 202 sets the system information modification bit ("1") as bit information. Therefore, bit information can be set in the short message. When the SIB is not to be changed in the next modification period, the control unit 230 does not need to set the system information modification bit. That is, the UE 100 may consider that the system information (e.g., SIB1 and / or other SIBXs other than SIB1) will be changed based on the system information change bit (which may be a value set in the system information change bit) included in the short message. Here, in this embodiment, SIB1 may include an SIB1 that is broadcast without a request from the UE 100 and / or an on-demand SIB1. The UE 100 may consider that the system information will be changed from the modification period next to the period in which the UE 100 received the short message with the system information change bit set (i.e., the current modification period).

[0163] The control unit 120 of the UE 100 performs monitoring at a PDCCH monitoring opportunity to receive a short message at a paging opportunity. That is, the control unit 120 may monitor a PDCCH with a CRC scrambled by the P-RNTI at a paging opportunity. If the control unit 120 successfully decodes the PDCCH, the control unit 120 may perform the process of step S912 below.

[0164] The modification period is set by system information (e.g., SIB1 and / or other SIBXs other than SIB1). The boundary of the modification period (MP) is defined, for example, by "SFN mod m=0" using an SFN value, where m is the number of radio frames constituting the MP. m may be determined based on information indicating a default paging cycle included in SIB1 and a coefficient. Here, the system information may be transmitted in cell C2.

[0165] Step S912: The control unit 120 of the UE 100 determines whether or not the system information (SI) will be changed from the next modification period based on the short message. For example, if the system information change bit is set in the short message, the control unit 120 determines that the SI will be changed from the next modification period. On the other hand, if the system information change bit is not set in the short message, the control unit 120 determines that the SI will not be changed from the next modification period.

[0166] If the control unit 120 determines that the SI is to be changed, the control unit 120 may execute the process of step S913. On the other hand, if the control unit 120 determines that the SI is not to be changed, the control unit 120 may omit the subsequent processes.

[0167] Step S913: The transmitter 111 of the UE 100 transmits a request for the on-demand SIB1 (i.e., an UL WUS) to the cell C2 before the start of the next modification period (MP2). For example, the transmitter 111 may start the process of step S40 in the current modification period (MP1). As described above, the current modification period may be the modification period in which a short message with the system information change bit set is received. The receiver 212 of the base station 202 receives the UL WUS from the UE 100 in the cell C2. That is, the transmitter 111 of the UE 100 may transmit information for requesting transmission of the on-demand SIB1 (i.e., an UL WUS) only in the current modification period (MP1). For example, the transmitter 111 of the UE 100 does not transmit information for requesting transmission of the on-demand SIB1 (i.e., an UL WUS) in the next modification period (MP2).

[0168] In response to receiving the request for the on-demand SIB1, the transmitter 211 of the base station 202 executes the process of step S914. On the other hand, if the transmitter 211 does not receive the request for the on-demand SIB1, the transmitter 211 may omit the process of step S914. Therefore, the transmitter 211 of the base station 202 does not need to transmit the on-demand SIB1 until receiving the request for the on-demand SIB1 in the next modification period (MP2).

[0169] Step S914: The transmitter 211 of the base station 202 transmits SIB1 in cell C2 from the start of the next modification period. For example, the transmitter 211 of the base station 202 may transmit SIB1 (periodically) in cell C2 from the start to the end of the next modification period. The receiver 112 of the UE 100 receives SIB1 from cell C2 from the start of the next modification period. Furthermore, the control unit 120 of the UE 100 may start a system information acquisition procedure from the start of the next modification period. For example, the control unit 120 of the UE 100 may execute the system information acquisition procedure in the next modification period. Note that the transmitter 211 of the base station 202 may end transmission of SIB1 in cell C2 after the end of the next modification period (MP2). The transmitter 211 does not need to transmit SIB1 until it receives a request for on-demand SIB1 from the UE 100.

[0170] As described above, the receiving unit 112 of the UE 100 may receive a short message from the cell C2 that supports the on-demand SIB1. The control unit 120 may determine, based on the short message, whether the system information will be changed from the next modification period. If the transmitting unit 111 determines that the system information will be changed, it may transmit a request for the on-demand SIB1 before the start of the next modification period. That is, if the transmitting unit 111 determines that the system information will be changed, it may transmit a request for the on-demand SIB1 only during the current modification period. This allows the base station 202 to know that the on-demand SIB1 is requested before the start of the next modification period. As a result, the base station 202 can transmit the SIB1 without delay from the next modification period. Furthermore, if the UL WUS configuration information is transmitted by system information (e.g., SIBX), the UL WUS configuration information may be changed from the next modification period. If UE 100 transmits UL WUS from the next modification period based on the UL WUS configuration information before the change, base station 200 may not be able to receive the UL WUS. By transmitting on-demand SIB1 during the current modification period, UE 100 can prevent base station 200 from failing to receive UL WUS due to a change in the UL WUS configuration information. Furthermore, if base station 200 does not receive a request for on-demand SIB1, it can omit transmitting SIB1. This allows for power saving.

[0171] (First Modification of Third Embodiment) A first modification of the third embodiment will be described with reference to Fig. 14. Previous descriptions may be omitted. In this modification, a case will be described in which the UE 100 does not transmit a request for on-demand SIB1.

[0172] Step S921: Corresponds to step S911. Here, when the control unit 230 of the base station 202 sets the system information change bit (“1”) as bit information in the short message, the control unit 230 may execute the process of step S923 regardless of whether or not the UE 100 requests the on-demand SIB1.

[0173] Alternatively, the control unit 230 of the base station 200 may include (or set) information indicating whether or not SIB1 will be broadcast in the next modification period (hereinafter, referred to as broadcast information) as bit information in the short message. For example, if SIB1 will be broadcast in the next modification period, the control unit 230 may include the broadcast information in the short message. In this case, the control unit 230 may execute the process of step S923.

[0174] On the other hand, if SIB1 will not be broadcast in the next modification period, the control unit 230 may not include the broadcast information in the short message. In this case, the control unit 230 may execute the same process as in the third embodiment.

[0175] In this modification example, the explanation will proceed on the assumption that SIB1 will be broadcast in the next modification period.

[0176] Step S922: Corresponds to step S912. However, if the control unit 120 of the UE 100 determines that the SI will be changed, it may execute the process of step S923. Therefore, the control unit 120 executes the process of receiving the SIB1 broadcast from the cell C2 in the next modification period without a request for the on-demand SIB1. The control unit 120 may assume that the SIB1 will be broadcast from the start of the next modification period. On the other hand, if the control unit 120 determines that the SI will not be changed, it may omit the subsequent processes.

[0177] Step S923 corresponds to step S914. After that, the transmitter 211 of the base station 202 may terminate the transmission of SIB1 in the cell C2 after the second modification period (MP2) that is the next modification period of the first modification period (MP1) that is the current modification period ends. The transmitter 211 does not need to transmit SIB1 until a request for on-demand SIB1 is received from the UE 100 in the third modification period that is the next modification period of the second modification period.

[0178] As described above, if the system information is changed in the modification period following the modification period in which the short message was transmitted, the transmitter 211 of the base station 202 may transmit the SIB1 in the next modification period without requesting the on-demand SIB1. If the controller 120 of the UE 100 determines that the system information is changed, the controller 120 may execute a process of receiving the SIB1 broadcast in the next modification period without requesting the on-demand SIB1. This prevents multiple UEs 100 from simultaneously transmitting requests for the on-demand SIB1 when multiple UEs 100 are present within the coverage of the cell C2. As a result, for example, congestion in the network 10 can be avoided.

[0179] Furthermore, the short message may include information indicating whether SIB1 will be broadcast in the next modification period. For example, if broadcast information is set in the short message, the control unit 120 may determine that SIB1 will be broadcast in the next modification period. If the control unit 120 determines that SIB1 will be broadcast in the next modification period, the control unit 120 may execute a process of receiving SIB1 in the next modification period without transmitting a request for on-demand SIB1. For example, if the control unit 120 determines that the system information will be changed and that SIB1 will be broadcast in the next modification period, the control unit 120 may execute a process of receiving SIB1 in the next modification period without transmitting a request for on-demand SIB1. This allows the UE 100 to appropriately determine whether to transmit a request for on-demand SIB1.

[0180] (Second Modification of Third Embodiment) A second modification of the third embodiment will be described with reference to Fig. 15. Previous descriptions may be omitted. In this modification, a case will be described in which the UE 100 determines whether or not the SIB1 has been changed.

[0181] Step S931: Corresponds to step S911. Here, the control unit 230 of the base station 202 may set or include at least one of the following information as bit information in the short message. The control unit 230 may set or include this information in the short message together with the system information change bit, or may set or include this information instead of the system information change bit.

[0182] The control unit 230 may set or include information indicating whether the on-demand SIB1 will be changed from the next modification period (hereinafter, SIB1 modification information) in the short message. For example, the control unit 230 may set or include the SIB1 modification information if the on-demand SIB1 will be changed from the next modification period. On the other hand, the control unit 230 may not set or include the SIB1 modification information if the on-demand SIB1 will not be changed from the next modification period.

[0183] In addition, the control unit 230 may set or include in the short message information indicating whether on-demand SIB1 will not be changed and system information other than on-demand SIB1 will be changed from the next change period (hereinafter referred to as other SIB change information).

[0184] Step S932: The control unit 120 of the UE 100 determines whether the on-demand SIB1 has been changed from the next modification period. If the control unit 120 determines based on the SIB1 modification information that the on-demand SIB1 has been changed from the next modification period, the control unit 120 may transmit a request for the on-demand SIB1 before the start of the next modification period (see step S913 in the third embodiment). Alternatively, the control unit 120 may assume that the on-demand SIB1 will be broadcast from the start of the next modification period (see step S923 in the first modification example). On the other hand, if the control unit 120 determines that the on-demand SIB1 has not been changed from the next modification period based on the SIB1 modification information, the control unit 120 may assume that other SIBs other than the on-demand SIB1 have been changed. For example, if the system information change bit is set in the short message and the on-demand SIB1 modification information is not included, the control unit 120 may assume that other SIBs other than the on-demand SIB1 have been changed from the next modification period. In this case, the control unit 120 may execute the process of step S933.

[0185] Furthermore, the control unit 120 may determine, based on the other SIB change information, whether other SIBs other than the on-demand SIB1 have been changed from the next change period. If the control unit 120 determines, based on the other SIB change information, that other SIBs have been changed from the next change period, the control unit 120 may omit (or skip) the processes of steps S933 and S934 and execute the process of step S935. That is, if the control unit 120 determines that the on-demand SIB1 will not be changed from the next change period and that other SIBs will be changed, the control unit 120 may execute the process of step S935. If the control unit 120 does not store a valid SIB1 for cell C2, the control unit 120 may execute the process of step S933 or S934. On the other hand, if the control unit 120 determines that other SIBs have not been changed from the next change period, the control unit 120 may omit the subsequent processes.

[0186] Step S933: The transmitter 111 of the UE 100 may transmit the UL WUS to the cell C2 after the start of the next modification period (MP2), rather than before the start of the next modification period. The receiver 212 of the base station 202 receives the UL WUS from the UE 100 in the cell C2 after the start of the next modification period.

[0187] Step S934: corresponds to step S914.

[0188] Step S935: The transmitter 111 of the UE 100 may transmit an SI request message to the cell C2 to request the changed SIB. The receiver 212 of the base station 202 may receive the SI request message in the cell C2.

[0189] Step S936: In the cell C2, the transmitter 211 of the base station 202 transmits an SI message including the changed SIB to the UE 100. The receiver 112 of the UE 100 receives the SI message.

[0190] As described above, the short message may be set with information indicating whether the on-demand SIB1 will be changed from the next modification period (i.e., SIB1 modification information). If the transmission unit 111 of the UE 100 determines that the on-demand SIB1 has been changed based on the information, the transmission unit 111 may transmit a request for the on-demand SIB1 before the start of the next modification period. This allows the UE 100 to understand that the on-demand SIB1 will be changed from the start of the next modification period, and allows the UE 100 to appropriately transmit a request for the on-demand SIB1.

[0191] Furthermore, the short message may be capable of setting information indicating whether or not system information other than the on-demand SIB1 has been changed without the on-demand SIB1 being changed from the next modification period (i.e., other SIB modification information). When the transmission unit 111 of the UE 100 determines based on the information that an SIB other than the on-demand SIB1 has been changed, the transmission unit 111 may transmit a request for the on-demand SIB1 after the start of the next modification period, rather than before the start of the next modification period. This allows the UE 100 to understand that the other SIBs will be changed from the start of the next modification period. By the UE 100 transmitting a request for the on-demand SIB1 after the start of the next modification period, the base station 202 can understand that it is requesting transmission of the other SIBs after the change. Therefore, the UE 100 can appropriately transmit a request for the on-demand SIB1.

[0192] Furthermore, the short message may be capable of setting information indicating whether or not system information other than the on-demand SIB1 has been changed without changing the on-demand SIB1 from the next change period (i.e., other SIB change information). When the transmission unit 111 of the UE 100 determines based on the information that other SIBs other than the on-demand SIB1 have been changed, the transmission unit 111 may transmit a request for other SIBs other than the on-demand SIB1. This allows the UE 100 to omit the operation of acquiring SIB1, thereby reducing the processing load of the UE 100.

[0193] (Third Modification of Third Embodiment) A third modification of the third embodiment will be described with reference to Fig. 16. Previous descriptions may be omitted. In this modification, a case will be described in which the UE 100 receives a short message regarding a warning message related to a public warning system (PWS). Public warning systems include, for example, an earthquake and tsunami warning system (ETWS) and a commercial mobile alert system (CMAS).

[0194] In this modification, the UE 100 is assumed to have capabilities related to ETWS and / or CMAS. That is, the UE 100 is compatible with ETWS and / or CMAS.

[0195] Step S941: The transmitter 211 of the base station 202 transmits, from the cell C2, a short message including the bit information (or in which the bit information is set), to the UE 100. The transmitter 211 may transmit the short message via downlink control information (DCI) on a PDCCH with a CRC scrambled by the P-RNTI.

[0196] In this embodiment, the bit information may be an indication of a warning message regarding the PWS (hereinafter referred to as a warning indication bit). The bit information may be, for example, an indication of an ETWS primary notification and / or an ETWS secondary notification and / or a CMAS notification (e.g., an etwsAndCmasIndication bit).

[0197] The control unit 230 of the base station 202 sets the warning indication bit ("1") as bit information when a warning message regarding the PWS is being broadcast. The control unit 230 does not need to set the warning indication bit ("1") when a warning message is not being broadcast.

[0198] The control unit 120 of the UE 100 performs monitoring at the PDCCH monitoring opportunity to receive a short message at the paging opportunity. The control unit 120 may monitor the PDCCH with a CRC scrambled by the P-RNTI. If the control unit 120 successfully decodes the PDCCH, it may perform the process of step S942 below.

[0199] Step S942: The control unit 120 of the UE 100 determines whether or not a warning message is being broadcast based on the short message. For example, if the warning indication bit is set in the short message, the control unit 120 determines that a warning message is being broadcast. On the other hand, if the warning indication bit is not set in the short message, the control unit 120 determines that a warning message is not being broadcast.

[0200] If the control unit 120 determines that a warning message has been broadcast, it may execute the process of step S943. On the other hand, if the control unit 120 determines that a warning message has not been broadcast, it may omit the subsequent processes.

[0201] Step S943: The transmitter 111 of the UE 100 immediately transmits a request for the on-demand SIB1 (i.e., an UL WUS) to the cell C2. The transmitter 111 may start the process of step S40, for example. The receiver 212 of the base station 202 receives the UL WUS from the UE 100 in the cell C2.

[0202] In response to receiving the request for the on-demand SIB1, the transmitting unit 211 of the base station 202 executes the process of step S944. On the other hand, if the transmitting unit 211 does not receive the request for the on-demand SIB1, the transmitting unit 211 may omit the process of step S944.

[0203] Step S944: The transmitter 211 of the base station 202 transmits SIB1 in cell C2. The receiver 112 of the UE 100 receives SIB1 from cell C2. After transmitting the on-demand SIB1, the receiver 112 of the UE 100 may immediately start (or attempt to start) a process of receiving (acquiring) SIB1 from cell C2. For example, the controller 120 of the UE 100 may start the system information acquisition procedure in the current modification period. Alternatively, the controller 120 of the UE 100 may start the system information acquisition procedure from the start of the next modification period.

[0204] SIB1 may include scheduling information for a predetermined SIB related to a warning message. The predetermined SIB may be, for example, SIB6 including an ETWS primary notification, SIB7 including an ETWS secondary notification, and / or SIB8 including a CMAS warning notification. Thus, the predetermined SIB may be composed of multiple types of SIBs.

[0205] Step S945: The transmitter 211 of the base station 202 transmits a predetermined SIB related to the warning message in cell C2. The receiver 112 of the UE 100 receives the predetermined SIB based on the scheduling information included in SIB1. For example, if the scheduling information for the predetermined SIB related to the warning message is included in SIB1, the control unit 120 of the UE 100 may start a system information acquisition procedure for the predetermined SIB based on the scheduling information. For example, if the control unit 120 of the UE 100 is capable of ETWS and the scheduling information (e.g., SchedulingInfo) included in SIB1 includes scheduling information for SIB6, the control unit 120 may immediately acquire SIB6. If the control unit 120 is capable of ETWS and the scheduling information included in SIB1 includes scheduling information for SIB7, the control unit 120 may immediately acquire SIB7. If the control unit 120 of the UE 100 is capable of supporting CMAS and the scheduling information included in the SIB1 includes scheduling information for the SIB8, the control unit 120 may immediately acquire the SIB8.

[0206] As described above, the receiving unit 112 of the UE 100 may receive a short message from the cell C2. The control unit 120 may determine whether a warning message regarding the PWS is being broadcast based on the short message. If the transmitting unit 111 determines that a warning message is being broadcast, it may transmit a request for an on-demand SIB1. As a result, if the base station 200 does not receive a request for an on-demand SIB1, it can omit transmitting the SIB1. This allows power saving.

[0207] (Fourth Modification of Third Embodiment) A fourth modification of the third embodiment will be described with reference to Fig. 17. Previous descriptions may be omitted. In this modification, a case will be described in which the UE 100 does not transmit a request for on-demand SIB1 when the UE 100 receives a short message regarding a warning message related to PWS.

[0208] Step S951: Corresponds to step S941. Here, when the control unit 230 of the base station 202 sets the warning indication bit as bit information in the short message, the control unit 230 may execute the process of step S953 regardless of whether or not the UE 100 requests the on-demand SIB1.

[0209] Step S952: Corresponds to step S942. However, if the control unit 120 of the UE 100 determines that a warning message has been broadcast, it may execute the process of step S953. Therefore, the control unit 120 executes the process of receiving the SIB1 broadcasted without a request for the on-demand SIB1. The control unit 120 may consider that the SIB1 has been broadcast. On the other hand, if the control unit 120 determines that a warning message has not been broadcast, it may omit the subsequent processes.

[0210] Steps S953 and S954: correspond to steps S944 and S945.

[0211] As described above, when broadcasting a warning message related to a public warning system, the transmitter 211 of the base station 202 may transmit the on-demand SIB1 without requesting the on-demand SIB1. When the controller 120 of the UE 100 determines that a warning message is being broadcast, the controller 120 may execute a process of receiving the SIB1 broadcast without requesting the on-demand SIB1. This prevents multiple UEs 100 from simultaneously transmitting requests for the on-demand SIB1 when multiple UEs 100 are present within the coverage of the cell C2. As a result, for example, congestion in the network 10 can be avoided.

[0212] (Fifth Modification of Third Embodiment) A fifth modification of the third embodiment will be described with reference to FIG. 18. Previous descriptions may be omitted. In this modification, a method will be described in which, when the UE 100 receives a short message regarding a warning message related to PWS, it determines whether to start the procedure for acquiring SIB1 or the procedure for acquiring a predetermined SIB. When the control unit 120 of the UE 100 receives the short message, it may execute the following process.

[0213] Step S961: As in step S942, the control unit 120 determines whether a warning message has been broadcast. If the control unit 120 determines that a warning message has been broadcast, it may execute the following process. On the other hand, if the control unit 120 determines that a warning message has not been broadcast, it may end the process of this operation.

[0214] Step S962: The control unit 120 determines whether to acquire an SIB 1 or an on-demand SIB 1. The control unit 120 may perform at least one of the following determinations.

[0215] First, the control unit 120 may determine whether a procedure for acquiring SIB1 (or on-demand SIB1) is necessary. For example, the control unit 120 may determine whether a procedure for acquiring SIB1 is necessary based on whether information indicating whether a procedure for acquiring SIB1 (or on-demand SIB1) is necessary (hereinafter, first bit information) is set in the short message.

[0216] For example, if the first bit information indicating the need for a procedure to acquire SIB1 (or on-demand SIB1) is set, the control unit 120 may determine that a procedure to acquire SIB1 is necessary. In this case, the control unit 120 may determine to acquire SIB1 or on-demand SIB1. The control unit 120 may execute the process of step S963.

[0217] On the other hand, if the first bit information is not set, the control unit 120 may determine that the procedure for acquiring SIB1 is not necessary. In this case, the control unit 120 may determine not to acquire SIB1 or on-demand SIB1. The control unit 120 may execute the process of step S964. Alternatively, the control unit 120 may execute the following second determination.

[0218] If the first bit information indicates that the procedure for acquiring SIB1 (or on-demand SIB1) is not necessary, the control unit 120 may perform the opposite determination.

[0219] Second, the control unit 120 may determine whether scheduling information for a predetermined SIB is stored. The control unit 120 may determine whether the scheduling information is stored, for example, based on whether information indicating a predetermined SIB that is being broadcast among multiple types of predetermined SIBs (hereinafter, referred to as second bit information) is set in the short message. The control unit 120 may identify the predetermined SIB that is being broadcast based on the second bit information. The control unit 120 may determine whether scheduling information for the identified predetermined SIB is stored.

[0220] For example, if second bit information indicating SIB6 and / or SIB7 as the predetermined SIB is set, the control unit 120 may identify SIB6 and / or SIB7 as the predetermined SIB. In this case, if the ETWS is supported, the control unit 120 may determine whether scheduling information for the predetermined SIB is stored. On the other hand, if the ETWS is not supported, the control unit 120 may terminate the process.

[0221] Furthermore, if second bit information indicating SIB8 as the predetermined SIB is set, the control unit 120 may identify SIB8 as the predetermined SIB. In this case, if CMAS is supported, the control unit 120 may determine whether scheduling information for the predetermined SIB is stored. On the other hand, if CMAS is not supported, the control unit 120 may terminate the process.

[0222] The control unit 120 may determine that the scheduling information of a specific SIB is stored when the scheduling information of the specific SIB identified based on the second bit information is stored. That is, the control unit 120 may determine that the scheduling information of the specific SIB is stored when the scheduling information of the specific SIB identified based on the second bit information is included in a stored SIB1 (e.g., a valid SIB1). On the other hand, the control unit 120 may determine that the scheduling information of the specific SIB is not stored when the scheduling information of the specific SIB identified based on the second bit information is not stored. That is, the control unit 120 may determine that the scheduling information of the specific SIB is not stored when the scheduling information of the specific SIB identified based on the second bit information is not included in a stored SIB1 (e.g., a valid SIB1).

[0223] Alternatively, the control unit 120 may determine that the scheduling information of a specific SIB is stored when the scheduling information of SIB6, SIB7, and SIB8 is stored, for example. On the other hand, when the scheduling information of any of SIB6, SIB7, and SIB8 is not stored, the control unit 120 may determine that the scheduling information of the specific SIB is not stored.

[0224] If the control unit 120 does not store the scheduling information for the predetermined SIB, for example, if the acquired on-demand SIB1 does not include the scheduling information for acquiring the predetermined SIB, the control unit 120 executes the process of step S963. On the other hand, if the control unit 120 stores the scheduling information for the predetermined SIB, the control unit 120 may execute the process of step S964.

[0225] Step S963: The control unit 230 starts a procedure to acquire SIB1. The control unit 120 may start a procedure to acquire on-demand SIB1. For example, when camped on the second cell, the control unit 120 may start a procedure to acquire on-demand SIB1.

[0226] Step S964: The control unit 230 starts a procedure for acquiring the predetermined SIB. The control unit 230 starts the procedure for acquiring the predetermined SIB using the scheduling information of the predetermined SIB included in the stored on-demand SIB1. For example, the control unit 230 may use the scheduling information of the predetermined SIB included in the on-demand SIB1 acquired before receiving the short message.

[0227] As described above, when the control unit 120 determines that a warning message is being broadcast, the control unit 120 may start a procedure for acquiring a predetermined SIB related to the warning message using the stored on-demand SIB 1. This allows the UE 100 to omit the procedure for acquiring SIB 1, thereby enabling the UE 100 to receive the warning message more quickly.

[0228] Furthermore, if the acquired on-demand SIB 1 does not include scheduling information for acquiring a predetermined SIB, the control unit 120 may start a procedure for acquiring the on-demand SIB 1. As a result, if the on-demand SIB 1 is necessary to acquire the predetermined SIB, the UE 100 can start a procedure for acquiring the on-demand SIB 1.

[0229] Further, the short message may be able to set information indicating whether a procedure for acquiring the on-demand SIB1 is necessary. Based on the information indicating whether a procedure for acquiring the on-demand SIB1 is necessary, the control unit 120 may start either a procedure for acquiring a predetermined SIB or a procedure for acquiring the on-demand SIB1. Based on the information, the UE 100 can execute an appropriate procedure for acquiring the predetermined SIB.

[0230] (Other Embodiments) In the above-described embodiments, the case where the first cell transmits the UL WUS configuration information has been mainly described, but the present invention is not limited to this. The second cell may transmit the UL WUS configuration information. The UL WUS configuration information may include information for setting the cell C2 as the target cell as the target cell, as the target cell information. In this case, the UE 100 may set the cell C2 as the target cell. On the other hand, if the UL WUS configuration information does not include this information, the UE 100 may set the cell C1 as the target cell.

[0231] In the first embodiment, a case has been described in which multiple scenarios are supported for the procedure of acquiring the on-demand SIB 1. In the second and third embodiments, multiple scenarios may be supported, or only one scenario may be supported.

[0232] In each of the above-described embodiments, the "on-demand SIB1" may be SIB1 acquired by the UE 100 in a different manner. The UE 100 may handle the on-demand SIB1 separately from a periodically broadcasted SIB1 (a conventional SIB1). Alternatively, the UE 100 may handle the on-demand SIB1 in the same manner as a conventional SIB1. Therefore, in the above description, the "on-demand SIB1" may be appropriately replaced with "SIB1." For example, the above-described SIB1 modification information may indicate whether the SIB1 has been modified from the next modification period.

[0233] The steps in the operations of each of the above-described embodiments do not necessarily have to be executed in chronological order according to the order depicted in the flow diagrams or sequence diagrams. For example, the steps in the operations may be executed in an order different from that depicted in the flow diagrams or sequence diagrams, or may be executed in parallel. Some of the steps in the operations may be deleted, or additional steps may be added to the process. Furthermore, the above-described operational flows are not limited to being executed independently, but may be executed by combining two or more operational flows. For example, some steps of one operational flow may be added to another operational flow, or some steps of one operational flow may be replaced with some steps of another operational flow.

[0234] In the above-described embodiment, an NR-based mobile communication system has been described as an example of the mobile communication system 1. However, the mobile communication system 1 is not limited to this example. The mobile communication system 1 may be a system conforming to the TS of either LTE (Long Term Evolution) or another generation system (e.g., the sixth generation) of the 3GPP standard. The base station 200 may be an eNB that provides E-UTRA user plane and control plane protocol termination for the UE 100 in LTE. The mobile communication system 1 may be a system conforming to the TS of a standard other than the 3GPP standard. The base station 200 may be an IAB (Integrated Access and Backhaul) donor or an IAB node. The base station 200 may be functionally divided into a CU (Central Unit) and a DU (Distributed Unit).

[0235] A program may be provided that causes a computer to execute each process performed by the UE 100 or the base station 200. The program may be recorded on a computer-readable medium. Using the computer-readable medium, the program can be installed on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM (Compact Disk Read Only Memory) or a DVD-ROM (Digital Versatile Disc Read Only Memory). Furthermore, circuits that execute each process performed by the UE 100 or the base station 200 may be integrated, and at least a part of the UE 100 or the base station 200 may be configured as a semiconductor integrated circuit (chip set, SoC (System On Chip)).

[0236] In the above-described embodiments, "transmit" may mean performing processing at least one layer in a protocol stack used for transmission, or may mean physically transmitting a signal wirelessly or via a wired connection. Alternatively, "transmit" may mean a combination of performing processing at least one layer and physically transmitting a signal wirelessly or via a wired connection. Similarly, "receive" may mean performing processing at least one layer in a protocol stack used for reception, or may mean physically receiving a signal wirelessly or via a wired connection. Alternatively, "receive" may mean a combination of processing at least one layer and physically receiving a signal wirelessly or via a wired connection. Similarly, "obtain / acquire" may mean obtaining information from stored information, obtaining information from information received from another node, or obtaining information by generating the information. Similarly, the terms "based on" and "depending on / in response to" do not mean "based only on" or "depending only on," unless expressly stated otherwise. The term "based on" means both "based only on" and "based at least in part on." Similarly, the term "depending on" means both "depending only on" and "depending at least in part on." Similarly, "include" and "comprise" do not mean including only the listed items, but may mean including only the listed items or may include additional items in addition to the listed items. Similarly, in this disclosure, "or" does not mean an exclusive or, but rather a logical or. Furthermore, any reference to elements using designations such as "first," "second," etc., as used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient method of distinguishing between two or more elements.Thus, a reference to a first and a second element does not imply that only two elements may be employed therein or that the first element must precede the second element in some way. In this disclosure, where articles are added by translation, such as a, an, and the in English, these articles shall include the plural unless the context clearly indicates otherwise.

[0237] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

[0238] (Additional Notes) Additional notes will be given regarding the features of the above-described embodiment.

[0239] (Supplementary Note 1) A communications device comprising: a receiver unit that receives a short message from a cell, the short message including information indicating a warning message related to a public warning system (PWS); and a controller that controls the controller to: retrieve an SIB1 message on demand from the cell based on reception of an acknowledgment to information requesting an on-demand system information block 1 (on-demand SIB1); retrieve the SIB1 message from the cell immediately based on reception of the short message; and retrieve a predetermined SIB related to the PWS based on scheduling information included in the SIB1 message.

[0240] (Supplementary Note 2) The communication device according to Supplementary Note 1, wherein the information indicating the warning message regarding the PWS is bit information indicating at least one of an Earthquake and Tsunami Warning System (ETWS) and a Commercial Mobile Alert System (CMAS).

[0241] (Supplementary Note 3) The communication device according to Supplementary Note 1 or 2, wherein the receiving unit receives configuration information for acquiring an on-demand SIB1 from another cell different from the cell, and the control unit requests the SIB1 message on-demand from the cell when the configuration information is valid.

[0242] (Supplementary Note 4) The communication device according to any one of Supplementary Notes 1 to 3, wherein the control unit controls the communication device to immediately acquire the SIB1 message from the cell based on reception of the short message, without requesting the SIB1 message from the cell on demand.

[0243] (Supplementary Note 5) The communication device according to any one of Supplementary Notes 1 to 4, wherein the short message includes information indicating whether SIB1 will be changed in a next change period, and the control unit transmits information requesting the on-demand SIB1 based on reception of the short message including the information indicating whether SIB1 will be changed in a next change period.

[0244] (Supplementary Note 6) The communication device according to any one of Supplementary Notes 1 to 5, wherein the receiving unit receives a Master Information Block (MIB) from the cell, the receiving unit receives configuration information for acquiring an on-demand SIB1 from another cell different from the cell, and the control unit, when transmitting information requesting the on-demand SIB1 to the cell, acquires the SIB1 message on-demand from the cell based on monitoring a physical downlink control channel in accordance with at least one of information indicating CORESET #0 and information indicating search space #0 included in the configuration information for acquiring the on-demand SIB1, and when receiving the short message from the cell, controls to immediately acquire the SIB1 message from the cell based on monitoring a physical downlink control channel in accordance with at least one of CORESET #0 and search space #0 indicated using the information included in the MIB.

[0245] (Supplementary Note 7) The communication device according to any one of Supplementary Notes 1 to 6, wherein the communication device has a capability related to the PWS.

[0246] (Supplementary Note 8) A base station comprising: a transmitter unit that transmits a Master Information Block (MIB) from a cell to a communication device, wherein the transmitter unit, when transmitting a short message including information indicating a warning message related to a Public Warning System (PWS) from the cell to the communication device, transmits a physical downlink control channel in accordance with at least one of CORESET #0 and search space #0 indicated using information included in the MIB; and, when receiving information requesting an On-Demand System Information Block 1 (On-Demand SIB1) from the communication device, transmits a physical downlink control channel in accordance with at least one of information indicating CORESET #0 and information indicating search space #0 included in setting information for acquiring On-Demand SIB1.

[0247] (Supplementary Note 9) A communication method comprising: a step of receiving a short message from a cell including information indicating a warning message related to a public warning system (PWS); a step of obtaining an on-demand system information block 1 (on-demand SIB1) message from the cell on demand based on receiving a positive response to information requesting the on-demand SIB1; a step of immediately obtaining the SIB1 message from the cell based on receiving the short message; and a step of controlling the obtaining of a predetermined SIB related to the PWS based on scheduling information included in the SIB1 message.

[0248] (Supplementary Note 10) The communication method according to Supplementary Note 9, wherein the information indicating the warning message regarding the PWS is bit information indicating at least one of an Earthquake and Tsunami Warning System (ETWS) and a Commercial Mobile Alert System (CMAS).

[0249] (Supplementary Note 11) The communication method according to Supplementary Note 9 or 10, further comprising: a step of receiving configuration information for acquiring an on-demand SIB1 from another cell different from the cell; and a step of requesting the SIB1 message on-demand from the cell when the configuration information is valid.

[0250] (Supplementary Note 12) The communication method according to any one of Supplementary Notes 9 to 11, further comprising the step of controlling, based on reception of the short message, to immediately obtain the SIB1 message from the cell without requesting the SIB1 message on demand from the cell.

[0251] (Supplementary Note 13) The communication method according to any one of Supplementary Notes 9 to 12, further comprising: a step of transmitting information requesting the on-demand SIB1 based on reception of the short message including information indicating whether SIB1 will be changed in a next modification period, wherein the short message includes information indicating whether SIB1 will be changed in a next modification period.

[0252] (Supplementary Note 14) The communication method according to any one of Supplementary Notes 9 to 13, further comprising: a step of receiving a Master Information Block (MIB) from the cell; a step of receiving configuration information for acquiring an on-demand SIB1 from another cell different from the cell; a step of acquiring the SIB1 message on-demand from the cell based on monitoring a physical downlink control channel in accordance with at least one of information indicating CORESET#0 and information indicating search space#0 included in the configuration information for acquiring the on-demand SIB1 when information requesting the on-demand SIB1 is transmitted to the cell; and a step of controlling to immediately acquire the SIB1 message from the cell based on monitoring a physical downlink control channel in accordance with at least one of CORESET#0 and search space#0 indicated using information included in the MIB when the short message is received from the cell.

[0253] (Supplementary Note 15) The communication method according to any one of Supplementary Notes 9 to 14, wherein the communication device has capabilities related to the PWS.

[0254] (Supplementary Note 16) A communication device comprising: a receiving unit that receives a short message from a cell that supports an on-demand SIB1, which is a system information block type 1, transmitted in response to a request from the communication device; a control unit that determines whether system information will be changed from a next modification period based on the short message; and a transmitting unit that transmits a request for the on-demand SIB1 before a start of the next modification period when it is determined that the system information will be changed.

[0255] (Supplementary Note 17) The communication device according to Supplementary Note 16, wherein the short message includes information indicating whether the on-demand SIB1 has been changed since the next modification period, and when the transmitting unit determines that the on-demand SIB1 has been changed based on the information, the transmitting unit transmits a request for the on-demand SIB1 before the start of the next modification period.

[0256] (Supplementary Note 18) The communication device according to Supplementary Note 16 or 17, wherein the short message includes information indicating whether the on-demand SIB1 has not been changed since the next modification period and system information other than the on-demand SIB1 has been changed, and when the transmitting unit determines based on the information that a SIB other than the on-demand SIB1 has been changed, it transmits a request for the on-demand SIB1 after the start of the next modification period, rather than before the start of the next modification period.

[0257] (Supplementary Note 19) The communication device according to any one of Supplementary Notes 16 to 18, wherein the short message includes information indicating whether the on-demand SIB1 has not been changed since the next change period and system information other than the on-demand SIB1 has been changed, and when the transmitting unit determines based on the information that other SIBs other than the on-demand SIB1 have been changed, it transmits a request for other SIBs other than the on-demand SIB1.

[0258] (Supplementary Note 20) A communication device comprising: a receiving unit that receives a short message from a cell that supports an on-demand SIB1, which is a system information block type 1, transmitted in response to a request from the communication device; and a control unit that determines, based on the short message, whether system information will be changed from a next modification period, wherein, when it is determined that the system information will be changed, the control unit executes a process of receiving SIB1 that will be broadcast in the next modification period without a request for the on-demand SIB1.

[0259] (Supplementary Note 21) The communication device according to Supplementary Note 20, wherein the short message includes information indicating whether the SIB1 will be broadcast in the next modification period, and when the control unit determines that the SIB1 will be broadcast in the next modification period, the control unit executes a process of receiving the SIB1 in the next modification period without transmitting a request for the on-demand SIB1.

[0260] (Supplementary Note 22) A communication device comprising: a receiving unit that receives a short message from a cell that supports an on-demand SIB1, which is a system information block type 1, and which is transmitted in response to a request from the communication device; a control unit that determines, based on the short message, whether a warning message related to a public warning system is being broadcast; and a transmitting unit that transmits a request for the on-demand SIB1 when it is determined that the warning message is being broadcast.

[0261] (Supplementary Note 23) A communication device comprising: a receiving unit that receives a short message from a cell that supports an on-demand SIB1, which is a system information block type 1, and which is transmitted in response to a request from the communication device; and a control unit that determines, based on the short message, whether a warning message related to a public warning system is being broadcast, wherein, when the control unit determines that the warning message is being broadcast, the control unit executes a process of receiving the SIB1 broadcast without a request for the on-demand SIB1.

[0262] (Supplementary Note 24) A communication device comprising: a receiving unit that receives a short message from a cell that supports an on-demand SIB1, which is a system information block type 1, transmitted in response to a request from the communication device; and a control unit that determines, based on the short message, whether a warning message related to a public warning system is being broadcast, wherein, when the control unit determines that the warning message is being broadcast, the control unit initiates a procedure to acquire a predetermined system information block (SIB) related to the warning message using the on-demand SIB1 that was acquired before receiving the short message.

[0263] (Supplementary Note 25) The communication device according to Supplementary Note 24, wherein the control unit starts a procedure for acquiring the on-demand SIB1 when the acquired on-demand SIB1 does not include scheduling information for acquiring the predetermined SIB.

[0264] (Supplementary Note 26) The communication device according to Supplementary Note 24 or 25, wherein the short message includes information indicating whether a procedure for acquiring the on-demand SIB1 is necessary, and the control unit starts either a procedure for acquiring the specified SIB or a procedure for acquiring the on-demand SIB1 based on the information indicating whether a procedure for acquiring the on-demand SIB1 is necessary.

[0265] (Supplementary Note 27) A communication method executed by a communication device, comprising: a step of receiving a short message from a cell supporting an on-demand SIB1, which is a system information block type 1, transmitted in response to a request from the communication device; a step of determining, based on the short message, whether or not system information will be changed from a next modification period; and a step of transmitting a request for the on-demand SIB1 before a start of the next modification period if it is determined that the system information will be changed.

[0266] (Supplementary Note 28) A communication method executed by a communication device, comprising: a step of receiving a short message from a cell supporting an on-demand SIB1, which is a system information block type 1 transmitted in response to a request from the communication device; a step of determining whether or not system information will be changed from a next modification period based on the short message; and a step of executing a process of receiving SIB1 broadcast in the next modification period without a request for the on-demand SIB1, if it is determined that the system information will be changed.

[0267] (Supplementary Note 29) A communication method executed by a communication device, comprising: a step of receiving a short message from a cell supporting an on-demand SIB1, which is a system information block type 1, transmitted in response to a request from the communication device; a step of determining based on the short message whether a warning message related to a public warning system is being broadcast; and a step of transmitting a request for the on-demand SIB1 if it is determined that the warning message is being broadcast.

[0268] (Supplementary Note 30) A communication method executed by a communication device, comprising: receiving a short message from a cell supporting an on-demand SIB1, which is a system information block type 1 transmitted in response to a request from the communication device; determining based on the short message whether a warning message related to a public warning system is being broadcast; and, if it is determined that the warning message is being broadcast, executing a process to receive the SIB1 broadcast without a request for the on-demand SIB1.

[0269] (Supplementary Note 31) A communication method executed by a communication device, comprising: receiving a short message from a cell supporting an on-demand SIB1, which is a system information block type 1 transmitted in response to a request from the communication device; determining based on the short message whether a warning message related to a public warning system is being broadcast; and, if it is determined that the warning message is being broadcast, initiating a procedure for acquiring a predetermined system information block (SIB) related to the warning message using the on-demand SIB1 acquired before receiving the short message.

[0270] (Supplementary Note 32) A base station comprising: a transmitter that transmits a short message from a cell that supports on-demand SIB1, which is a system information block type 1 that is transmitted in response to a request from a communication device; and the transmitter that transmits SIB1 in the next modification period without a request for the on-demand SIB1 if system information is to be changed in the next modification period after the modification period in which the short message was transmitted.

[0271] (Supplementary Note 33) A base station comprising: a transmitter that transmits a short message from a cell that supports an on-demand SIB1, which is a system information block type 1 that is transmitted in response to a request from a communication device; when the transmitter receives a request for the on-demand SIB1, the transmitter transmits the on-demand SIB1 from a modification period next to a modification period in which the short message was transmitted; and the base station is capable of setting information in the short message indicating whether the on-demand SIB1 has been modified from the next modification period.

[0272] (Supplementary Note 34) A base station comprising: a transmitter for transmitting a short message from a cell supporting an on-demand SIB1, which is a system information block type 1 transmitted in response to a request from a communication device; wherein the transmitter transmits the on-demand SIB1 without a request for the on-demand SIB1 when broadcasting a warning message related to a public warning system.

[0273] (Supplementary Note 35) A base station comprising: a transmitter for transmitting a short message from a cell supporting an on-demand SIB1, which is a system information block type 1, transmitted in response to a request from the communication device; and capable of setting information in the short message indicating whether a procedure for acquiring the on-demand SIB1 is required.

Claims

1. A communications device comprising: a receiver that receives a short message from a cell containing information indicating a warning message related to a public warning system (PWS); and a controller that controls the controller to: retrieve an on-demand system information block 1 (SIB1) message from the cell on demand based on receiving a positive response to information requesting an on-demand SIB1; immediately retrieve the SIB1 message from the cell based on receiving the short message; and retrieve a specified SIB related to the PWS based on scheduling information included in the SIB1 message.

2. The communication device of claim 1, wherein the information indicating a warning message regarding the PWS is bit information indicating at least one of the Earthquake and Tsunami Warning System (ETWS) and the Commercial Mobile Alert System (CMAS).

3. A communication device as described in claim 1 or 2, wherein the receiving unit receives configuration information for acquiring an on-demand SIB1 from a cell other than the cell, and the control unit requests the SIB1 message from the cell on demand when it has valid configuration information.

4. The communication device according to claim 1 or 2, wherein the control unit controls the device to immediately obtain the SIB1 message from the cell based on the reception of the short message, without requesting the SIB1 message from the cell on demand.

5. The communication device according to claim 1 or 2, wherein the short message includes information indicating whether SIB1 will be changed in the next change period, and the control unit transmits information requesting the on-demand SIB1 based on reception of the short message including information indicating whether SIB1 will be changed in the next change period.

6. The communication device of claim 1 or 2, wherein the receiving unit receives a master information block (MIB) from the cell, the receiving unit receives configuration information for acquiring on-demand SIB1 from another cell different from the cell, and the control unit, when transmitting information requesting the on-demand SIB1 to the cell, acquires the SIB1 message on-demand from the cell based on monitoring a physical downlink control channel in accordance with at least one of information indicating CORESET #0 and information indicating search space #0 included in the configuration information for acquiring the on-demand SIB1, and when receiving the short message from the cell, controls to immediately acquire the SIB1 message from the cell based on monitoring a physical downlink control channel in accordance with at least one of CORESET #0 and search space #0 indicated using the information included in the MIB.

7. The communication device according to claim 1 or 2, wherein the communication device has capabilities related to the PWS.

8. A base station comprising: a transmitter unit that transmits a master information block (MIB) from a cell to a communication device, wherein the transmitter unit, when a short message including information indicating a warning message related to a public warning system (PWS) is transmitted from the cell to the communication device, transmits a physical downlink control channel in accordance with at least one of CORESET #0 and search space #0 indicated using information contained in the MIB; and, when information requesting an on-demand system information block 1 (on-demand SIB1) is received from the communication device, transmits a physical downlink control channel in accordance with at least one of information indicating CORESET #0 and information indicating search space #0 included in configuration information for acquiring on-demand SIB1.

9. A communication method executed in a communication device, comprising: receiving a short message from a cell containing information indicating a warning message related to a public warning system (PWS); retrieving an on-demand system information block 1 (on-demand SIB1) message from the cell on demand based on receiving an acknowledgment to information requesting an on-demand SIB1; immediately retrieving the SIB1 message from the cell based on receiving the short message; and controlling the retrieval of a predetermined SIB related to the PWS based on scheduling information included in the SIB1 message.

10. The communication method according to claim 9, wherein the information indicating a warning message regarding the PWS is bit information indicating at least one of the Earthquake and Tsunami Warning System (ETWS) and the Commercial Mobile Alert System (CMAS).

11. A communication method according to claim 9 or 10, further comprising the steps of: receiving configuration information for acquiring an on-demand SIB1 from a cell different from the cell; and, if the configuration information is valid, requesting the SIB1 message on-demand from the cell.

12. The communication method according to claim 9 or 10, further comprising a step of controlling, based on reception of the short message, to immediately obtain the SIB1 message from the cell without requesting the SIB1 message on demand from the cell.

13. The communication method according to claim 9 or 10, further comprising the step of: the short message including information indicating whether SIB1 will be changed in the next modification period; and transmitting information requesting the on-demand SIB1 based on receipt of the short message including information indicating whether SIB1 will be changed in the next modification period.

14. The communication method according to claim 9 or 10, further comprising the steps of: receiving a Master Information Block (MIB) from the cell; receiving configuration information for acquiring an on-demand SIB1 from another cell different from the cell; when information requesting the on-demand SIB1 is transmitted to the cell, acquiring the SIB1 message on-demand from the cell based on monitoring a physical downlink control channel in accordance with at least one of information indicating CORESET #0 and information indicating search space #0 included in the configuration information for acquiring the on-demand SIB1; and when the short message is received from the cell, controlling to immediately acquire the SIB1 message from the cell based on monitoring a physical downlink control channel in accordance with at least one of CORESET #0 and search space #0 indicated using information included in the MIB.

15. The communication method according to claim 9 or 10, wherein the communication device has capabilities related to the PWS.

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