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 serving cell, system information including information relating to settings for requesting an on-demand system information block type 1 (SIB1); and a control unit (120). The information relating to the setting for requesting the on-demand SIB1 includes one or more physical cell identifiers, and information indicating the time and frequency resources of a physical random access channel (PRACH) corresponding to each of the one or more physical cell identifiers. The control unit performs control to transmit a request for the on-demand SIB1 to a cell identified by any one of the one or more physical cell identifiers using a PRACH resource indicated on the basis of the information indicating the time and frequency resources of the PRACH.

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 No. 2024-061781, filed April 5, 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 broadcast 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] "R1-2400600" (Discussion on the enhancement to support on demand SIB1 for idle / inactive mode UE)

[0005] A communication device according to a first aspect includes a receiving unit configured to receive system information from a serving cell, the system information including information regarding a configuration for requesting an on-demand system information block type 1 (SIB1), and a control unit. The information regarding the configuration for requesting the on-demand SIB1 includes one or more physical cell identifiers and information indicating time and frequency resources of a Physical Random Access Channel (PRACH) corresponding to each of the one or more physical cell identifiers. The control unit controls transmission of the on-demand SIB1 request to a cell identified by any of the one or more physical cell identifiers using PRACH resources indicated based on the information indicating the time and frequency resources of the PRACH.

[0006] A base station according to a second aspect includes a transmitter configured to transmit system information to a communication device, the system information including information regarding a configuration for requesting an on-demand system information block type 1 (SIB1). The information regarding the configuration for requesting the on-demand SIB1 includes information indicating one or more physical cell identifiers and time and frequency resources of a physical random access channel (PRACH) corresponding to each of the one or more physical cell identifiers. The information indicating the time and frequency resources of the PRACH indicates PRACH resources for the communication device to transmit a request for the on-demand SIB1 to a cell identified by any of the one or more physical cell identifiers.

[0007] A communication method according to a third aspect is a communication method executed by a communication device. The communication method includes a step of receiving system information from a serving cell, the system information including information regarding a configuration for requesting an on-demand system information block type 1 (SIB1). The information regarding the configuration for requesting the on-demand SIB1 includes one or more physical cell identifiers and information indicating time and frequency resources of a physical random access channel (PRACH) corresponding to each of the one or more physical cell identifiers. The communication method further includes a step of controlling transmission of the request for the on-demand SIB1 to a cell identified by any of the one or more physical cell identifiers using PRACH resources indicated based on the information indicating the time and frequency resources of the PRACH.

[0008] A communication method according to a fourth aspect is a communication method executed by a base station. The communication method includes a step of transmitting system information including information regarding a configuration for requesting an on-demand system information block type 1 (SIB1) to a communication device. The information regarding the configuration for requesting the on-demand SIB1 includes information indicating one or more physical cell identifiers and time and frequency resources of a physical random access channel (PRACH) corresponding to each of the one or more physical cell identifiers. The information indicating the time and frequency resources of the PRACH indicates PRACH resources for the communication device to transmit a request for the on-demand SIB1 to a cell identified by any of the one or more physical cell identifiers.

[0009] 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 sequence diagram illustrating a first operation example. FIG. 6 is a diagram illustrating a first operation example. FIG. 7 is a sequence diagram illustrating a second operation example. FIG. 8 is a sequence diagram illustrating a third operation example. FIG. 9 is a sequence diagram illustrating a fourth operation example. FIG. 10 is a sequence diagram illustrating a fifth operation example. FIG. 11 is a sequence diagram illustrating a sixth operation example. FIG. 12 is a sequence diagram illustrating a seventh operation example. FIG. 13 is a sequence diagram illustrating an eighth operation example. FIG. 14 is a sequence diagram illustrating a ninth operation example. FIG. 15 is a sequence diagram illustrating a tenth operation example. FIG. 16 is a flowchart illustrating an eleventh operation example.

[0010] 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.

[0011] One of the objectives 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 an SIB of an NES cell.

[0012] (System Configuration) First, the configuration of a mobile communication system 11 according to this embodiment will be described with reference to Fig. 1. The mobile communication system 11 is, for example, a system that complies with the 3GPP Technical Specification (TS). In the following, the mobile communication system 11 will be described using as an example a 3GPP standard 5th Generation System (5G system), i.e., a mobile communication system based on NR (NR (New Radio) radio access).

[0013] The mobile communication system 11 includes a network 10 and a user equipment (UE) 100 that communicates with the network 10. The network 10 includes a 5G radio access network, a Next Generation Radio Access Network (NG-RAN) 20, and a 5G core network, a 5G Core Network (5GC) 30.

[0014] 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. The UE 100 may be a transport vehicle other than a vehicle (e.g., a ship, an airplane, etc.) or a device provided therein. The UE 100 may be a sensor or a device provided therein. The UE 100 may be called 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. The UE 100 is an example of a terminal, and the terminal may include factory equipment, etc.

[0015] 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).

[0016] 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.

[0017] (Configuration Example of Protocol Stack) Next, a configuration example of a protocol stack according to this embodiment will be described with reference to FIG.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] The PDCP layer performs header compression / decompression and encryption / decryption.

[0023] 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).

[0024] 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 an RRC connection exists between the RRC of the UE 100 and the RRC of the base station 200, the UE 100 is in an RRC connected state. When there is no RRC connection between the RRC of the UE 100 and the RRC of the base station 200, the UE 100 is in an RRC idle state. When the RRC connection between the RRC of the UE 100 and the RRC of the base station 200 is suspended, the UE 100 is in an RRC inactive state.

[0025] 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.

[0026] The UE 100 has an application layer and the like in addition to the radio interface protocol.

[0027] (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.

[0028] (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.

[0029] 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.

[0030] 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.

[0031] As described above, although the introduction of on-demand SIB1 as one of the NESs is being considered, there is a concern that UE 100 may not be able to properly acquire on-demand SIB1 from a target cell when there are multiple cells (hereinafter, sometimes referred to as second cells) that support on-demand SIB1. In UE 100 according to this embodiment, the receiver 112 receives, from the first cell, an SIB1 request configuration related to a configuration for requesting on-demand SIB1 from multiple second cells that support on-demand SIB1 broadcast in response to a request. The transmitter 111 transmits a request for on-demand SIB1 to one second cell using uplink resource information corresponding to one second cell from uplink resource information used for transmitting requests corresponding to each of the multiple second cells included in the SIB1 request configuration. As a result, UE100 can receive on-demand SIB1 from the target second cell by sending a request for on-demand SIB1 using uplink resource information included in the SIB1 request setting corresponding to the target second cell, and can properly acquire on-demand SIB1.

[0032] Furthermore, even if the UE 100 fails to request the on-demand SIB1, there is a concern that the UE 100 may continue to attempt to receive the SIB1 without being able to determine whether the on-demand SIB1 request has failed. In the UE 100 according to this embodiment, the receiver 112 receives from the first cell a SIB1 request configuration related to a configuration for requesting the on-demand SIB1 from a second cell that supports the on-demand SIB1 broadcast in response to the request. The transmitter 111 transmits a request for the on-demand SIB1 to the second cell based on the SIB1 request configuration. The controller 120 determines the waiting period based on period information included in the SIB1 request configuration and related to the waiting period until a positive response to the request is received. As a result, if the UE 100 does not receive a positive response until the determined waiting period has elapsed, the UE 100 can determine that the request for the SIB1 has failed. As a result, the UE 100 can avoid continuing to attempt to receive the SIB1, and can appropriately acquire the SIB1. Furthermore, the network can control the waiting period of the UE 100 using the period information.

[0033] Furthermore, in a case where the UE 100 requests the on-demand SIB1, a method for acquiring other SIBs different from the on-demand SIB1 is not specified. Therefore, there is a concern that the UE 100 may not be able to properly acquire the other SIBs. In the UE 100 according to this embodiment, the receiving unit 112 receives, from the first cell, a SIB1 request configuration related to a configuration for requesting the on-demand SIB1 from a second cell that supports the on-demand SIB1 broadcast upon request. The control unit 120 executes control to acquire other system information blocks (SIBs) of the second cell different from the on-demand SIB1 based on the SIB1 request configuration. As a result, the UE 100 executes an operation to acquire the other SIBs based on the SIB1 request configuration, so that the network can control the acquisition of the other SIBs, and the other SIBs of the second cell can be properly acquired.

[0034] (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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] The base station 200 configured as described above is a base station that manages a first cell. In the base station 200, the transmitter 211 transmits, from the first cell to the UE 100, an SIB1 request configuration related to a configuration for requesting an on-demand SIB1 from a plurality of second cells that support system information block type 1 (on-demand SIB1) broadcast upon request. The SIB1 request configuration includes uplink resource information used to transmit the request corresponding to each of the plurality of second cells. As a result, the UE 100 can receive the SIB1 from the target second cell by transmitting a request for the SIB1 using the uplink resource information included in the SIB1 request configuration corresponding to the target second cell, and can appropriately acquire the SIB1.

[0039] Furthermore, the transmitting unit 211 transmits, from the first cell to the UE 100, an SIB1 request configuration regarding a configuration for requesting a second cell that supports system information block type 1 (on-demand SIB1) broadcast upon request. The SIB1 request configuration includes period information regarding a waiting period until an acknowledgment for the request is received. As a result, if the UE 100 does not receive an acknowledgment until the determined waiting period has elapsed, the UE 100 can determine that the request for SIB1 has failed. As a result, the UE 100 can avoid continuing to attempt to receive SIB1, and can appropriately acquire SIB1. Furthermore, the network can control the waiting period of the UE 100 using the period information.

[0040] Furthermore, the transmission unit 211 transmits, from the first cell to the UE 100, an SIB1 request configuration related to a configuration to request a second cell that supports system information block type 1 (on-demand SIB1) broadcast upon request. The SIB1 request configuration is used by the UE 100 to acquire other system information blocks (SIBs) of the second cell that are different from the on-demand SIB1. As a result, the UE 100 performs an operation to acquire other SIBs based on the SIB1 request configuration, and the network can control the acquisition of other SIBs, making it possible to appropriately acquire other SIBs of the second cell.

[0041] (First Operation Example) A first operation example according to this embodiment will be described with reference to Figures 5 and 6. Previously described explanations may be omitted.

[0042] In FIG. 5 , UE 100 may be in an RRC idle state or an RRC inactive state with cell C1 managed by base station 200. Alternatively, UE 100 may be in an RRC connected state with cell C1. That is, 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, or 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. That is, cell C1 may be a serving cell.

[0043] Cell C1, cell C2, and cell C3 may be managed by the same base station 200. Cell C1, cell C2, and cell C3 may be managed by different base stations 200. For example, one base station 200 may manage cell C1 and cell C2. A first base station 201 may manage cell C1, and a second base station 202 may manage cell C2. In this operation example, the explanation will proceed assuming that base station 200 manages cell C1 and cell C2, and another base station 200 manages cell C3.

[0044] In this operation example, a cell that periodically broadcasts (i.e., transmits) system information block type 1 (SIB1) is referred to as a first cell. The first cell may be a cell that does not support on-demand SIB1 (i.e., the on-demand SIB1 function). The first cell may be a cell that broadcasts SIB1 without a request from the UE 100. The first cell may be referred to as an anchor cell. The first cell may be a general cell that does not transmit on-demand SIB1. In this operation example, the first cell is cell C1. Cell C1 may be, for example, a primary cell (i.e., a P-cell) for the UE 100.

[0045] In this operation example, a cell that does not periodically broadcast (i.e., transmit) system information block type 1 (SIB1) is referred to as a second cell. The second cell may be a cell that transmits on-demand SIB1. The second cell may be a cell that supports on-demand SIB1 (i.e., the on-demand SIB1 function). The second cell may be a cell that starts broadcasting SIB1 based on a request from the UE 100. The second cell may be referred to as a non-anchor cell or an NES cell. The second cell may be a special cell that transmits on-demand SIB1. For example, the second cell (i.e., base station 200 managing the second cell) may broadcast information indicating that it supports on-demand SIB1. For example, the information indicating that it supports on-demand SIB1 may be included in the MIB (i.e., SSB), SIB1, or system information (system information block) other than SIB1. Furthermore, information indicating that the second cell supports the on-demand SIB1 may be transmitted from the first cell (i.e., the base station 200 that manages the first cell) to the UE 100. For example, the information indicating that the on-demand SIB1 is supported may be included in a SIB1 request configuration, which will be described later. The UE 100 may perform an operation related to an on-demand SIB1 request, which will be described later, based on the information indicating that the on-demand SIB1 is supported. In this operation example, the cell C2 and the cell C3 are the second cells.

[0046] Note that, in this specification, for UE 100, communication with base station 200 may be communication with a cell. For example, base station 200 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 base station 200. Similarly, base station 200 may receive information / messages, etc. from UE 100 via a certain cell (or in a certain cell). For UE, transmitting information / messages, etc. to a cell may be transmitting information / messages, etc. to base station 200.

[0047] Step S101: The transmitter 211 of the base station 200 transmits an SIB1 request configuration from the cell C1 to the UE 100. The receiver 112 of the UE 100 receives the SIB1 request configuration from the cell C1.

[0048] The SIB1 request configuration may be information (e.g., On-demand SIB1 request config.) regarding a configuration for requesting on-demand SIB1 from the second cell. That is, the SIB1 request configuration may be a configuration (i.e., information) used for transmitting information indicating a request for broadcasting SIB1. Hereinafter, transmitting information indicating a request for broadcasting SIB1 will also be simply referred to as transmitting a request. The SIB1 request configuration may be included in an RRC message. As shown in FIG. 5 , the SIB1 request configuration may be included, for example, in SIB1 from cell C1 (i.e., SIB1 message). The SIB1 request configuration may be included in a system information block related to the SIB of another cell. That is, the SIB1 request configuration may be included in a system information message (SI message, hereinafter also referred to as SIBX). The UE 100 may request the cell C1 to broadcast the SIBX. In response to a request from UE 100, base station 200 may transmit a SIBX including an SIB1 request configuration to UE 100.

[0049] When UE 100 is in the RRC connected state, the transmission unit 211 of the base station 200 may transmit an individual RRC message including the SIB1 request configuration from the cell C1 to UE 100. The reception unit 112 of UE 100 may receive the individual RRC message from the cell C1. The control unit 120 of UE 100 may store the SIB1 request configuration even after transitioning from the RRC connected state to the RRC idle state or the RRC inactive state. Note that in this operation example, when UE 100 is in the RRC connected state, it transitions to the RRC idle state or the RRC inactive state before step S103 described below.

[0050] The SIB1 request configuration may include uplink resource information used to transmit the request. The uplink resource information may include, for example, configuration information for configuring an uplink bandwidth portion (uplink BWP) for transmitting the request (hereinafter referred to as ULBWP information). The uplink resource information may also include configuration information used to specify random access parameters for transmitting the request (hereinafter referred to as RACH resource information).

[0051] The ULBWP information may include, for example, information used to configure an additional uplink bandwidth portion (not for the initial BWP) (e.g., BWP-Uplink information). The ULBWP information may include, for example, information used to configure common parameters for the uplink BWP (e.g., BWP-UplinkCommon). The ULBWP information may include BWP information (e.g., BWP) used to configure parameters of the bandwidth portion. The BWP information may include at least one of information indicating the frequency location and bandwidth of the bandwidth portion configured by the BWP information (e.g., locationAndBandwidth), information indicating an extended cyclic prefix for the bandwidth portion configured by the BWP information (e.g., cyclicPrefix), and information indicating the subcarrier spacing for the bandwidth portion configured by the BWP information (e.g., subcarrierSpacing). Here, the information indicating the extended cyclic prefix may indicate whether an extended cyclic prefix or a normal cyclic prefix is ​​used in the bandwidth portion configured by the BWP information, and the information indicating the subcarrier spacing may indicate the subcarrier spacing used for all channels and / or reference signals in the bandwidth portion configured by the BWP information.

[0052] The ULBWP information may include initial uplink BWP information (e.g., initialUplinkBWP) indicating a configuration for the initial uplink BWP. The initial uplink BWP information may be information used only for requesting the on-demand SIB1. Therefore, for example, an RRC message including the SIB1 request configuration may include initial uplink BWP information for initial access to the second cell, separate from the initial uplink BWP information. Alternatively, the initial uplink BWP information for requesting the on-demand SIB1 may also be used for initial access to the second cell. The initial uplink BWP information may be common to both the configuration for requesting the on-demand SIB1 and the configuration for initial access. In this case, the RRC message including the SIB1 request configuration does not need to include the initial uplink BWP information for initial access to the second cell. In this embodiment, the RRC message may include a system information message and / or a separate RRC message.

[0053] The RACH resource information may include information used to specify cell-specific random access parameters (e.g., RACH-ConfigCommon). The RACH resource information may include information used to specify cell-specific random access parameters (e.g., RACH-ConfigCommon). The RACH resource information may include information used to specify cell-specific random access parameters for both normal random access and beam failure recovery (e.g., RACH-ConfigGeneric). The RACH resource information may be information used only for requesting the on-demand SIB1. Thus, for example, an RRC message including a SIB1 request configuration may include RACH resource information for initial access to the second cell, separate from the RACH resource information. Alternatively, the RACH resource information for requesting the on-demand SIB1 may also be used for initial access to the second cell. The RACH resource information may be a common setting for the request of the on-demand SIB1 and for the initial access. In this case, the RRC message including the SIB1 request setting does not need to include the RACH resource information for the initial access to the second cell.

[0054] That is, the RACH resource information may include random access parameters used by the UE 100 to request the on-demand SIB1. For example, the RACH resource information may include information for setting a random access opportunity for the request for the on-demand SIB1. The random access opportunity may correspond to an opportunity for transmitting a physical random access channel (PRACH) (i.e., transmitting message 1 in the random access procedure). That is, the RACH resource information may include information for setting time and / or frequency resources (indexes corresponding to time and / or frequency resources) for the PRACH. Furthermore, the RACH resource information may include information for setting an index of a random access preamble for the request for the on-demand SIB1. For example, the random access preamble is defined as 64 numbers having indices from 0 to 63, and the random access preamble for the request for the on-demand SIB1 may be set by including information for setting the starting index of the random access preamble in the RACH resource information. That is, the UE 100 may request a broadcast of the on-demand SIB1 from the cell C2 (i.e., start of broadcast) by transmitting a random access preamble at a random access opportunity of the uplink BWP. The RACH resource information may also include information for setting a period (window) for receiving a message 2 corresponding to the transmission of the PRACH. For example, the period for receiving the message 2 may be defined as the length of a slot, and the UE 100 may consider the random access procedure to be successfully completed if it receives the message 2 during that period in response to the transmission of the PRACH. That is, as described below, the UE 100 may consider the request for the on-demand SIB1 to be successfully completed if it receives the message 2 during that period.

[0055] The uplink resource information may include information indicating a resource configuration for message 1 used by UE 100 to request SIB1 or an SI message for SIB1 (for example, si-RequestConfig). Also, the uplink resource information may include information including information necessary for requesting SIB1 or an SI message for SIB1 (for example, SI-SchedulingInfo). Also, information indicating a resource configuration for message 1 used by UE 100 (for example, si-RequestConfig) may include uplink resource information and / or information including information necessary for requesting SIB1 or an SI message for SIB1 (for example, SI-SchedulingInfo). For example, information indicating a resource configuration for message 1 used by UE 100 (for example, si-RequestConfig) may correspond to the SIB1 request configuration. Base station 200 may configure UE 100 to request on-demand SIB1 by including an SIB1 request setting in the RRC message. That is, as described below, UE 100 may determine whether to transmit an on-demand SIB1 request. For example, UE 100 may request on-demand SIB1 when the SIB1 request setting is included in the RRC message. Furthermore, UE 100 may not request on-demand SIB1 when the SIB1 request setting is not included in the RRC message. Furthermore, base station 200 may configure UE 100 to request on-demand SIB1 by including uplink resource information (e.g., random access parameters) in the SIB1 request setting. That is, UE 100 may request on-demand SIB1 when the SIB1 request setting includes uplink resource information. Furthermore, when the SIB1 request configuration does not include uplink resource information, the UE 100 does not need to request the on-demand SIB1.

[0056] The SIB1 request configuration may include a cell identifier corresponding to the second cell. The cell identifier is an identifier for identifying a cell. The cell identifier may be, for example, a physical cell identifier (e.g., physCellId). The cell identifier may be associated with uplink resource information. The uplink resource information associated with the cell identifier may be uplink resource information for the second cell identified by the cell identifier.

[0057] The SIB1 request configuration may include information regarding the transmission of the on-demand SIB1 (hereinafter, referred to as transmission information). The transmission information may include information indicating at least one of the number of transmissions of the on-demand SIB1, the transmission period of the on-demand SIB1, and the transmission duration of the on-demand SIB1. The transmission information may include information indicating a modification period during which the content of the system information from the second cell may be modified. The transmission information may include information regarding a synchronization signal (SS) burst set composed of SSBs from the second cell. For example, the information regarding the SS burst set may include information indicating the period of the SS burst set. Here, the period of the SS burst set may be referred to as the SSB period. The information regarding the SS burst set may also include information indicating the position in the time domain at which the SSBs are actually transmitted. The information regarding the SS burst set may also include information indicating an association (correspondence) between the SSBs and random access opportunities and / or information indicating a threshold used for selecting the SSBs. The transmission information may include, for example, information indicating the number of times (e.g., a multiple) of the modification period and / or the period of the SS burst set. The control unit 120 of the UE 100 may determine at least one of the number of times to transmit the on-demand SIB1, the transmission period of the on-demand SIB1, and the transmission duration of the on-demand SIB1 based on the modification period and / or the period of the SS burst set.

[0058] Here, the modification period may be a period used for updating a system information message (e.g., updating the content of SIB1). That is, a system information message with the same content may be broadcast in the modification period. For example, the modification period may be specified by a radio frame number and may be set (determined) based on a value (modificationPeriodCoeff) and / or a paging cycle (e.g., a default paging cycle). That is, the SIB1 request configuration may include information indicating a value used to set the modification period and / or information indicating the cycle. Here, the information indicating the cycle may be information indicating the paging cycle (e.g., a default paging cycle). Furthermore, the information indicating the cycle may be information corresponding to the paging cycle (e.g., a default paging cycle) in cell C2.

[0059] Further, the modification period (for example, the boundary of the modification period) may be specified by the value of the system frame number (SFN). Here, information indicating the value of the SFN may be included in the MIB transmitted on the PBCH included in the SSB. That is, the UE 100 may acquire the on-demand SIB1 from the cell C2 based on the SIB1 request setting from the cell C1 and / or the SSB from the cell C2 (for example, information indicating the value of the SFN included in the MIB). Furthermore, the information indicating the value of the SFN may be included in the SIB1 request setting and transmitted from the cell C1.

[0060] As described above, the UE 100 may request the broadcast of the on-demand SIB1 based on the transmission of a random access preamble in a random access opportunity configured for the request of the on-demand SIB1. Here, the UE 100 may transmit the request for the on-demand SIB1 only in the current modification period. That is, since the random access opportunity and / or the random access preamble configured for the request of the on-demand SIB1 may be changed from the start of the next modification period, the UE 100 may transmit the request for the SIB1 only in the current modification period. Alternatively, the UE 100 may transmit the request for the on-demand SIB1 from the start of the next modification period. That is, since the random access opportunity and / or the random access preamble used in the current modification period may not correspond to the random access opportunity and / or the random access preamble for the request of the on-demand SIB1, the UE 100 may transmit the request for the on-demand SIB1 from the start of the next modification period.

[0061] Here, base station 200 may notify UE 100 of an update of the system information message based on information included in the short message. For example, the short message may be transmitted on a PDCCH with a cyclic redundancy check (CRC, also referred to as a CRC parity bit) scrambled by a paging radio network temporary identifier (P-RNTI). When UE 100 is notified of the update of the system information message, UE 100 may acquire the system information message in the next modification period. For example, UE 100 may monitor the PDCCH with a CRC scrambled by the P-RNTI based on successful completion of the request for on-demand SIB1. UE 100 may receive notification of the update of the system information message (e.g., on-demand SIB1) based on the short message transmitted on the PDCCH with the CRC scrambled by the P-RNTI, and may acquire the system information message (e.g., on-demand SIB1) from the start of the next modification period.

[0062] Furthermore, UE 100 may select a random access opportunity to be used for requesting on-demand SIB1 based on information about the SS burst set. For example, UE 100 may determine a random access opportunity associated with an SSB based on information indicating an association (correspondence) between the SSB and the random access opportunity. UE 100 may also measure received power (e.g., reference reference signal power (RSRP)) based on the SSB, select an SSB with received power higher than a threshold set by information indicating a threshold used for selecting the SSB, and select a random access opportunity associated with the selected SSB. UE 100 may select a random access opportunity based on information about the SS burst set and request broadcast (i.e., start of broadcast) of on-demand SIB1 by transmitting a random access preamble in the selected random access opportunity.

[0063] Furthermore, the SIB1 request configuration may include information regarding the transmission of the on-demand SIB1 request (hereinafter, referred to as transmission request information). The transmission request information may include information indicating at least one of the number of transmissions of the on-demand SIB1 request, the transmission period of the on-demand SIB1 request, and the transmission duration of the on-demand SIB1 request. The transmission request information may include, for example, information indicating the number of modification periods and / or the period of the SS burst set (e.g., multiples). The control unit 120 of the UE 100 may determine at least one of the number of transmissions of the on-demand SIB1 request, the transmission period of the on-demand SIB1 request, and the transmission duration of the on-demand SIB1 request based on the modification period and / or the period of the SS burst set.

[0064] The transmission information may include information indicating the transmission status of the on-demand SIB1. The information indicating the transmission status of the on-demand SIB1 may indicate whether the on-demand SIB1 is being (temporarily) transmitted. For example, when the control unit 230 of the base station 200 is transmitting the on-demand SIB1 from the cell C2 in response to a request from another UE 100, the control unit 230 may include, in the SIB1 request configuration, transmission information indicating that the on-demand SIB1 is being transmitted. That is, the SIB1 request configuration may include information indicating that the on-demand SIB1 has already been broadcast in the corresponding cell. On the other hand, for example, when the control unit 230 is not transmitting the on-demand SIB1 from the cell C2, the control unit 230 may include, in the SIB1 request configuration, transmission information indicating that the on-demand SIB1 is not being transmitted. That is, the SIB1 request configuration may include information indicating whether the on-demand SIB1 is being broadcast in the corresponding cell (i.e., whether it is being broadcast or not). In addition, the control unit 230 of the base station 200 may update the validity information, which will be described later, included in the SIB1 request configuration depending on whether or not the on-demand SIB1 is being transmitted (i.e., whether or not the on-demand SIB1 is being transmitted).

[0065] The SIB1 request configuration may include validity information used to determine the validity of the SIB1 request configuration. The validity information may include, for example, information (e.g., valueTag) indicating whether the SIB1 request configuration stored by the UE 100 is identical to the newly received SIB1 request configuration. The validity information may include information indicating a timer value or a period used to measure the validity of the SIB1 request configuration. The control unit 120 of the UE 100 may start a timer or period to which the timer value is set based on the validity information (e.g., based on receiving a validity information value that is not identical to the stored validity information value). As described above, the SIB1 request configuration may be included in a system information message (SIB). That is, the validity information may be applied to the system information message (SIB) including the validity information.

[0066] For example, UE 100 may use a valid, stored version of the system information message after cell (re)selection. That is, after performing cell (re)selection to cell C2, UE 100 may request on-demand SIB1 from cell C2 based on a system information message (e.g., SIB1 request configuration) configured from cell C1. UE 100 may store the system information message (e.g., SIB1 request configuration) as a valid version of the system information message. UE 100 may also determine whether the stored system information message is valid based on validity information included in the received system information message. For example, UE 100 may consider the stored system information message to be valid if the validity information (validity information value) included in the system information message is the same as the validity information (validity information value) included in the stored system information message. As described above, the SIB1 request configuration may include a cell identifier. Here, the validity information may be configured corresponding to the cell identifier (i.e., may be configured for each of multiple cells). For example, if the validity information (value of the validity information) included in a system information message for a certain cell (e.g., SIB1 request setting for cell C2) is the same as the validity information (value of the validity information) included in a system information message for the certain cell (e.g., SIB1 request setting for cell C2) that UE100 has stored, UE100 may consider the system information message for the certain cell (e.g., SIB1 request setting for cell C2) that UE100 has stored to be valid.

[0067] The SIB1 request configuration (hereinafter, sometimes referred to as a first SIB1 request configuration) may include information about the second cell corresponding to each of the multiple second cells. The information about the second cell may be, for example, the SIB1 request configuration of the corresponding second cell (hereinafter, sometimes referred to as a second SIB1 request configuration). The first SIB1 request configuration (specifically, "On-demand SIB1 request config." in FIG. 5) may include multiple second SIB1 request configurations. Therefore, the SIB1 request configuration may be configured by multiple SIB1 request configurations (i.e., multiple second SIB1 request configurations) corresponding to multiple second cells. Therefore, the transmission unit 211 of the base station 200 may transmit multiple SIB1 request configurations from the cell C1 to the UE 100. The reception unit 112 of the UE 100 may receive multiple SIB1 request configurations from the cell C1. Furthermore, the SIB1 request configuration may be configured by SIB1 request configurations corresponding to a plurality of second cells. Therefore, the transmission unit 211 of the base station 200 may transmit the SIB1 request configurations corresponding to a plurality of second cells from the cell C1 to the UE 100. The reception unit 112 of the UE 100 may receive the SIB1 request configurations corresponding to a plurality of second cells from the cell C1.

[0068] Each of the multiple SIB1 request configurations (i.e., multiple second SIB1 request configurations) may include uplink resource information. Furthermore, each of the multiple SIB1 request configurations may include uplink resource information corresponding to multiple second cells and cell identifiers (of the second cells) corresponding to the uplink resource information. Furthermore, each of the SIB1 request configurations may include uplink resource information corresponding to multiple second cells. Furthermore, each of the SIB1 request configurations may include uplink resource information corresponding to multiple second cells and cell identifiers of the second cells corresponding to the uplink resource information.

[0069] The SIB1 request configuration may be configured as a list corresponding to multiple second cells. The SIB1 request configuration (list) may have a configuration similar to that of a list of neighbor cell information. The neighbor cell information may be, for example, a list in which cell identifiers of multiple neighbor cells that are candidates for cell reselection are entered. The neighbor cell information may be an intra-frequency neighbor cell list (e.g., intraFreqNeighBellList) that is a list of intra-frequency neighbor cells accompanied by specific cell reselection parameters. Alternatively, the neighbor cell information may be an inter-frequency neighbor cell list (e.g., interFreqNeighBellList) that is a list of inter-frequency neighbor cells accompanied by specific cell reselection parameters. The receiving unit 112 of the UE 100 may have received the list of neighbor cell information (i.e., the intra-frequency neighbor cell list and / or the inter-frequency neighbor cell list) from the first cell. For example, the intra-frequency neighbor cell list may be included in system information block type 3 (SIB3) from the first cell. The inter-frequency neighbor cell list may also be included in the system information block type 4 (SIB4) from the first cell.

[0070] The (list of) SIB1 request configuration may be configured as a neighbor cell list (e.g., NeighCellList) consisting of a list of neighbor cell information (e.g., NeighCellInfo) as shown in Figure 6 (see E1 in Figure 6). Therefore, the SIB1 request configuration may include a cell identifier (e.g., PhysCellId) of the second cell and uplink resource information (e.g., BWP-UplinkCommon) of the second cell (see E2 in Figure 6). The uplink resource information may include ULBWP information (e.g., BWP) and RACH resource information (e.g., RACH-ConfigCommon) (see E3 in Figure 6).

[0071] The SIB1 request configuration may include the same number of entries as the list of neighboring cell information, and may be listed in the same order as the list of neighboring cell information. In this case, if the control unit 120 of the UE 100 holds the list of neighboring cell information, it can determine which SIB1 request configuration corresponds to which second cell based on the position at which the SIB1 request configuration is entered in the list of SIB1 request configuration. Therefore, each SIB1 request configuration does not need to include the cell identifier of the corresponding second cell. Note that, in the list of neighboring cell information (i.e., the intra-frequency neighboring cell list and / or the inter-frequency neighboring cell list), the SIB1 request configuration field of a cell that is not the second cell may include, for example, dummy information that is ignored by the UE 100.

[0072] That is, UE 100 may determine the second cell based on the intra-frequency neighbor cell list included in SIB3. For example, UE 100 may transmit a request for on-demand SIB1 based on a plurality of SIB1 request configurations included in SIB1 and the intra-frequency neighbor cell list included in SIB3. That is, UE 100 may transmit a request for on-demand SIB1 to a cell (e.g., cell C2) determined based on the intra-frequency neighbor cell list included in SIB3, using the corresponding SIB1 request configuration included in SIB1. UE 100 may also determine the second cell based on the inter-frequency neighbor cell list included in SIB4. For example, UE 100 may transmit a request for on-demand SIB1 based on a plurality of SIB1 request configurations included in SIB1 and the inter-frequency neighbor cell list included in SIB4. That is, UE100 may transmit a request for on-demand SIB1 to a cell (e.g., cell C2) determined based on the inter-frequency neighbor cell list included in SIB4 using the corresponding SIB1 request setting included in SIB1.

[0073] The SIB1 request configuration may be configured by only the SIB1 request configuration corresponding to the second cell in the neighboring cell information list (i.e., the intra-frequency neighboring cell list and / or the inter-frequency neighboring cell list), in which case each SIB1 request configuration may include a cell identifier of the second cell and uplink resource information of the second cell.

[0074] As described above, the SIB1 request configuration may have the same configuration as a list of neighbor cell information (i.e., an intra-frequency neighbor cell list and / or an inter-frequency neighbor cell list). Thus, the SIB1 request configuration may be divided into a list of intra-frequency second cells and a list of inter-frequency second cells, or the SIB1 request configuration may be a single common list for the intra-frequency second cells and the inter-frequency second cells.

[0075] The receiving unit 112 of the UE 100 may receive a list of cell identifiers of second cells and a list of SIB1 request configurations associated with each cell identifier. That is, one SIB1 request configuration may include a list of cell identifiers associated with each of a plurality of second cells and a list of configurations for requests for on-demand SIB1. That is, for example, each of the information included in the SIB1 request configuration described above may be included as a list. For example, cell identifiers corresponding to each of a plurality of second cells may be configured as a list, and a plurality of uplink resource information, a plurality of transmission information, a plurality of transmission request information, a plurality of information indicating the transmission status of on-demand SIB1, a plurality of validity information, and / or a plurality of downlink resource information described later may be configured correspondingly as a list. For example, UE 100 may determine uplink resource information, transmission information, transmission request information, information indicating a transmission status of on-demand SIB1, and / or validity information corresponding to a cell identifier from the order of cell identifiers included in the list and the order of uplink resource information, transmission information, transmission request information, information indicating a transmission status of on-demand SIB1, and / or validity information included in the list. In this embodiment, it is described that a plurality of SIB1 request settings are set, but the setting of a plurality of SIB1 request settings also includes the setting of corresponding settings and / or information as a list.

[0076] That is, when transmitting SIB1 request configurations including information on a plurality of second cells to UE 100, control unit 230 of base station 200 may notify UE 100 of validity information corresponding to each of the SIB1 request configurations. Here, control unit 230 of base station 200 may notify UE 100 of one piece of validity information common to a plurality of SIB1 request configurations. That is, one piece of validity information (value of the validity information) may be transmitted to UE 100 for a plurality of SIB1 request configurations corresponding to a plurality of cells included in the system information message.

[0077] Here, the RRC message (system information message and / or individual RRC message) may be a message exchanged at the RRC layer in the UE 100 and / or the base station 200. Furthermore, the random access procedure may be exchanged at the MAC layer in the UE 100 and / or the base station 200. That is, for example, the RRC layer in the UE 100 may notify the MAC layer of the SIB1 request setting, and the MAC layer in the UE 100 may perform (trigger) a random access procedure for requesting the on-demand SIB1 based on the notification of the SIB1 request setting from the RRC layer. Further, for example, the MAC layer in UE 100 notifies the RRC layer of information indicating that it has received an acknowledgement message (described later) (i.e., that the random access procedure for the request for on-demand SIB1 has been successfully completed), and the RRC layer in UE 100 may acquire the on-demand SIB1 (may start acquiring the on-demand SIB1) based on the notification of the reception of the acknowledgement message from the MAC layer. Furthermore, monitoring of the PDCCH with a CRC scrambled by the system information radio network temporary identifier (SI-RNTI) is performed by the PHY layer in UE 100. That is, the MAC layer in UE 100 notifies the PHY layer of information indicating that it has received the acknowledgement message, and the PHY layer in UE 100 may (may start) monitoring the PDCCH with a CRC scrambled by the SI-RNTI based on the notification of the reception of the acknowledgement message from the MAC layer.

[0078] Step S102: The transmitter 211 of the base station 200 transmits the SSB from cell C2. The transmitter 211 of another base station 200 transmits the SSB from cell C3. The receiver 112 of the UE 100 receives the SSB from each of cell C2 and cell C3. The SSB is a synchronization signal (SS) and a physical broadcast channel (PBCH) block (SS / PBCH block). The SSB may also be a synchronization signal block.

[0079] Step S103: The control unit 120 of the UE 100 performs cell (re)selection. The control unit 120 (re)selects an appropriate cell as a cell to camp on based on the SSB measurement results received from each cell. In this operation example, the description will proceed assuming that cell C2 is (re)selected. That is, the description will proceed assuming that cell C2 is (re)selected as the serving cell.

[0080] Step S104: The transmitter 111 of the UE 100 transmits a request for an on-demand SIB1 (hereinafter referred to as an on-demand SIB1 request) to the cell C2 based on the SIB1 request setting. The receiver 212 of the base station 200 receives the on-demand SIB1 request from the UE 100 in the cell C2.

[0081] The transmitter 111 of the UE 100 transmits an on-demand SIB1 request to the cell C2 using radio resources (e.g., random access opportunities) based on the uplink resource information. The transmitter 111 may transmit the on-demand SIB1 request to the cell C2, for example, in the uplink BWP set by the ULBWP information. The transmitter 111 may transmit the on-demand SIB1 request to the cell C2, for example, using random access parameters set by the RACH resource information.

[0082] When the SIB1 request configuration includes information about a plurality of second cells (cells C2 and C3 in this embodiment), the control unit 120 of the UE 100 may transmit an on-demand SIB1 request to cell C2 based on the SIB request configuration corresponding to cell C2, which is the (re)selected cell. That is, the UE 100 may transmit an on-demand SIB1 request to a cell (e.g., cell C2) based on the SIB1 request configuration corresponding to the (re)selected and / or camped-on cell. The control unit 120 may transmit the on-demand SIB1 request to cell C2 based on, for example, the SIB1 request configuration associated with a cell identifier indicating cell C2 among the SIB1 request configurations.

[0083] Here, as described above, the control unit 120 of the UE 100 may determine whether to transmit an on-demand SIB1 request. For example, when the SIB1 request configuration includes a SIB1 request configuration corresponding to the cell C2, the control unit 120 may determine to transmit an on-demand SIB1 request corresponding to the cell C2. On the other hand, when the SIB1 request configuration does not include a SIB1 request configuration corresponding to the cell C2, the control unit 120 may determine not to transmit an on-demand SIB1 request corresponding to the cell C2.

[0084] When the control unit 120 determines to transmit an on-demand SIB1 request, the control unit 120 may execute this step. On the other hand, when the control unit 120 determines not to transmit an on-demand SIB1 request, the control unit 120 may execute the operation of receiving SIB1 as usual without transmitting the on-demand SIB1 request.

[0085] Furthermore, when the SIB request configuration includes information indicating the transmission status of on-demand SIB1, the control unit 120 of the UE 100 may determine whether to transmit an on-demand SIB1 request based on the information indicating the transmission status of on-demand SIB1. When the information indicates that on-demand SIB1 is not being transmitted, the control unit 120 of the UE 100 may determine to transmit an on-demand SIB1 request. On the other hand, when the information indicates that on-demand SIB1 is being (temporarily) transmitted, the control unit 120 of the UE 100 may determine not to transmit an on-demand SIB1 request.

[0086] The control unit 120 may determine whether the SIB1 request configuration corresponding to cell C2 is valid based on the validity information. The control unit 120 may determine, for example, whether the value of the validity information corresponding to the SIB1 request configuration and the value of the validity information corresponding to the newly received SIB1 request configuration are the same. That is, even after performing cell (re)selection to cell C2, the UE 100 may use the SIB1 request configuration configured from cell C1 and stored. Furthermore, the UE 100 may update the content of the stored SIB1 request configuration based on the value of the validity information indicating that the content of the SIB1 request configuration has been updated, rather than updating the content every time it receives the SIB1 request configuration that is included in a system information message and periodically broadcasted.

[0087] Furthermore, the control unit 120 may determine that the SIB1 request setting is invalid when a timer set with a timer value based on the validity information expires. The control unit 120 may determine to transmit an on-demand SIB1 request when the timer is running or stopped (or not yet started). The control unit 120 may also transmit an on-demand SIB1 request during a period when the SIB1 request setting is valid. In other words, if the SIB1 request setting is invalid, it is not necessary to transmit an on-demand SIB1 request.

[0088] The control unit 120 may execute this step if it determines that the SIB1 request setting is valid. On the other hand, if it determines that the SIB1 request setting is not valid, it may execute control to acquire a new SIB1 request setting from the cell C1. The control unit 120 may execute the operation of step S101, for example.

[0089] Step S105: The transmitter 211 of the base station 200 broadcasts the on-demand SIB1 from the cell C2 in response to the request from the UE 100. The receiver 112 of the UE 100 receives the on-demand SIB1 from the cell C2.

[0090] The control unit 230 of the base station 200 may determine at least one of the number of transmissions of the on-demand SIB1, the transmission period of the on-demand SIB1, and the transmission duration of the on-demand SIB1 based on the transmission information. The control unit 230 may determine at least one of the number of transmissions of the on-demand SIB1, the transmission period of the on-demand SIB1, and the transmission duration of the on-demand SIB1 based on the modification period and / or the period of the SS burst set. The control unit 230 may control the transmission of the on-demand SIB1 based on the determined number of transmissions of the on-demand SIB1, the transmission period of the on-demand SIB1, and the transmission duration of the on-demand SIB1. Furthermore, the control unit 230 of the base station 200 may immediately start broadcasting the on-demand SIB1 in response to a request from the UE 100. That is, the control unit 230 of the base station 200 may start broadcasting the on-demand SIB1 in response to a request from the UE 100 during the current modification period. Here, in response to a request from UE 100, control unit 230 of base station 200 may start broadcasting on-demand SIB1 from the start of the next modification period. As described above, base station 200 may control UE 100 to acquire on-demand SIB1 by notifying the UE 100 of an update of the system information message based on information included in the short message. Here, for on-demand SIB1, base station 200 may control UE 100 to acquire on-demand SIB1 without notifying the UE 100 of an update of the system information message.

[0091] The receiving unit 112 of the UE 100 may receive the on-demand SIB1 from the cell C2 based on the transmission information. The control unit 120 of the UE 100 may execute control to receive the on-demand SIB1 based on the transmission information. For example, the control unit 120 may determine at least one of the number of transmissions of the on-demand SIB1, the transmission period of the on-demand SIB1, and the transmission duration of the on-demand SIB1 based on the transmission information. Furthermore, the control unit 120 may determine at least one of the number of transmissions of the on-demand SIB1, the transmission period of the on-demand SIB1, and the transmission duration of the on-demand SIB1 based on the modification period and / or the period of the SS burst set. The control unit 120 may control to receive the on-demand SIB1 at the timing when the on-demand SIB1 is being transmitted based on at least one of the determined number of transmissions of the on-demand SIB1, the transmission period of the on-demand SIB1, and the transmission duration of the on-demand SIB1. Furthermore, the control unit 120 of the UE 100 (for example, the RRC layer of the UE 100) may immediately start acquiring the on-demand SIB1 based on notification of the reception of the acknowledgment message from the MAC layer of the UE 100. That is, the control unit 120 of the UE 100 may start acquiring the on-demand SIB1 in response to the request for the on-demand SIB1 in the current modification period. Here, the control unit 120 of the UE 100 may start acquiring the on-demand SIB1 in response to the request for the on-demand SIB1 from the start of the next modification period. That is, the control unit 120 of the UE 100 may start acquiring the on-demand SIB1 corresponding to the request for the on-demand SIB1 from the start of the next modification period in which the request for the on-demand SIB1 is transmitted. Also, the control unit 120 of the UE 100 may start acquiring the on-demand SIB1 from the start of the next modification period in which the reception of the acknowledgment message from the MAC layer of the UE 100 is notified.

[0092] Thereafter, the control unit 230 of the UE 100 may perform initial access to the cell C2, for example, based on the received on-demand SIB1.

[0093] As described above, the transmitter 211 of the base station 200 may transmit, from the first cell to the UE 100, an SIB1 request configuration related to a configuration for requesting the on-demand SIB1 from a plurality of second cells that support the on-demand SIB1. The SIB1 request configuration may include uplink resource information used for transmitting the request corresponding to each of the plurality of second cells. The receiver 112 of the UE 100 receives, from the first cell, the SIB1 request configuration related to a configuration for requesting the on-demand SIB1 from a plurality of second cells that support the on-demand SIB1. The transmitter 111 transmits a request for the on-demand SIB1 to one second cell using uplink resource information corresponding to one second cell from the uplink resource information used for transmitting the request corresponding to each of the plurality of second cells included in the SIB1 request configuration. As a result, UE100 can receive on-demand SIB1 from the target second cell by sending a request for on-demand SIB1 using uplink resource information included in the SIB1 request setting corresponding to the target second cell, and can properly acquire on-demand SIB1.

[0094] Furthermore, the SIB1 request configuration may include uplink resource information corresponding to a plurality of second cells and cell identifiers of the second cells corresponding to the uplink resource information. This allows the control unit 230 of the UE 100 to grasp the uplink resource information corresponding to the target second cell even when receiving a plurality of pieces of uplink resource information. As a result, the UE 100 can transmit a request for the on-demand SIB1 using appropriate uplink resource information corresponding to the target second cell.

[0095] Furthermore, the transmitting unit 211 of the base station 200 may transmit a list of neighboring cell information, in which each of the cell identifiers of a plurality of neighboring cells that are candidates for cell reselection is entered, from the first cell to the UE 100. The receiving unit 112 of the UE 100 may receive, from the first cell, the list of neighboring cell information, in which each of the cell identifiers of a plurality of neighboring cells that are candidates for cell reselection is entered. The SIB1 request configuration may include the same number of entries as the list of neighboring cell information, and may be listed in the same order as the list of neighboring cell information. As a result, since the information included in the SIB1 request configuration corresponds to the neighboring cell information, the UE 100 can determine which cell the SIB1 request configuration corresponds to. As a result, the UE 100 can transmit a request for on-demand SIB1 using appropriate uplink resource information corresponding to the target second cell.

[0096] The uplink resource information may also include configuration information for configuring an uplink bandwidth portion for transmitting the request. This allows the UE 100 to appropriately request the on-demand SIB1 by transmitting the request for the on-demand SIB1 in the uplink bandwidth portion configured by the configuration information.

[0097] Furthermore, the uplink resource information may include configuration information used to identify random access parameters for transmitting the request. As a result, the UE 100 can appropriately request the on-demand SIB1 by transmitting the request for the on-demand SIB1 using the random access parameters identified by the configuration information.

[0098] The SIB1 request configuration may also include transmission information regarding transmission of the on-demand SIB1 from each of the second cells. The receiving unit 112 of the UE 100 may receive the on-demand SIB1 from the second cell based on the transmission information. This allows the UE 100 to appropriately acquire the on-demand SIB1.

[0099] The transmission information may include information indicating at least one of the number of transmissions of the on-demand SIB1, the transmission period of the on-demand SIB1, and the transmission duration of the on-demand SIB1. The receiving unit 112 of the UE 100 can appropriately acquire the on-demand SIB1 by knowing at least one of the number of transmissions of the on-demand SIB1, the transmission period of the on-demand SIB1, and the transmission duration of the on-demand SIB1.

[0100] Furthermore, the transmitting unit 211 of the base station 200 may transmit validity information used to determine the validity of the SIB1 request configuration from the first cell to the UE 100. The receiving unit 112 of the UE 100 may receive the validity information used to determine the validity of the SIB1 request configuration from the first cell. The control unit 120 of the UE 100 may determine whether or not the SIB1 request configuration corresponding to one second cell is valid, based on the validity information. This allows the UE 100 to appropriately request the on-demand SIB1 by transmitting a request for the on-demand SIB1 based on the valid SIB1 request configuration.

[0101] Furthermore, when the SIB1 request configuration corresponding to one second cell is not valid, the control unit 120 of the UE 100 may execute control to acquire a new SIB1 request configuration from the first cell. As a result, the UE 100 can appropriately request the on-demand SIB1 by transmitting a request for the on-demand SIB1 based on the new SIB1 request configuration.

[0102] (Second Operation Example) A second operation example will be described with reference to Fig. 7. Previously described explanations may be omitted. In this operation example, the operation from requesting on-demand SIB1 to acquiring on-demand SIB1 will be mainly described. In this operation example, a request for on-demand SIB1 is made by message 1. This operation example may be executed in the first operation example.

[0103] The description will proceed assuming that the UE 100 has already received the SIB1 request configuration from the cell C1. The SIB1 request configuration may include downlink resource information.

[0104] The downlink resource information may include information indicating a downlink bandwidth portion (DLBWP) in which a message 2 described below is transmitted. The downlink resource information may include information (e.g., PDCCH-ConfigCommon) indicating a configuration for receiving (monitoring) a PDCCH described below. The information may be information used for configuring cell-specific PDCCH parameters. The information may be information for configuring a common search space (CSS). The CSS may be, for example, a type 1 PDCCH CSS for receiving message 2. The CSS may also be a type 1 PDCCH CSS for the PDCCH corresponding to message 2. The downlink resource information may also include information for configuring a value of the RA-RNTI. The CSS may also be a type 2 PDCCH CSS for receiving a short message. That is, the CSS may be a Type 2 PDCCH CSS for a PDCCH with a CRC scrambled by the P-RNTI. Also, the downlink resource information may include information for setting the value of the P-RNTI.

[0105] Step S201: Based on the SIB1 request configuration, the transmitter 111 of the UE 100 transmits Message 1 for an on-demand SIB1 request to the cell C2 in the random access procedure. For example, the transmitter 111 of the UE 100 may transmit the PRACH (Message 1) using a random access opportunity configured for the cell C2 and / or a random access preamble configured for the cell C2. The receiver 212 of the base station 200 receives Message 1 for an on-demand SIB1 request from the UE 100 in the cell C2. This step may correspond to Step S104.

[0106] Step S202: The transmitter 211 of the base station 200 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.

[0107] The PDCCH carries a cyclic redundancy check (CRC) scrambled by a random access radio network temporary identifier (RA-RNTI). The PDCCH carries scheduling information (also referred to as downlink assignment) indicating radio resource allocation in message 2. That is, for example, resources for a 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.

[0108] 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 the 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 (window) corresponding to the transmission of the PRACH described above.

[0109] Step S203: 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.

[0110] Message 2 may be an acknowledgment message to message 1.

[0111] The receiver 112 of the UE 100 may receive the message 2 based on the downlink resource information. The receiver 112 may receive the message 2, for example, in the downlink BWP based on the downlink resource information. That is, the controller 120 of the UE 100 may receive the random access response based on the downlink resource information. For example, the controller 120 of the UE 100 may monitor the PDCCH with the CRC scrambled by the RA-RNTI in the Type 1 PDCCH CSS of the downlink bandwidth portion.

[0112] When receiving the message 2, the control unit 120 of the UE 100 may determine whether the message 2 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 in the on-demand SIB1 request.

[0113] 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 notify the RRC layer that it has received an acknowledgment message for the SIB1 request (Message 1). Furthermore, the control unit 120 (for example, the MAC layer) may notify the PHY layer that it has received a message for acknowledging the SIB1 request (message 1).

[0114] Step S204: The transmitter 211 of the base station 200 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.

[0115] The PDCCH carries a Cyclic Redundancy Check (CRC) scrambled by the System Information Radio Network Temporary Identifier (SI-RNTI). The PDCCH carries scheduling information indicating the radio resource allocation for the SI messages.

[0116] 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 notification of the reception of a message for an acknowledgment to the SIB1 request (message 1) from the MAC layer. The control unit 120 may determine the control resource set #0 (CORESET #0) and the search space #0 (SS #0) in which the downlink control information (DCI) dedicated to SIB1 exists based on the SSB (specifically, the MIB) of the cell C2. That is, 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 information included in the MIB. The control unit 120 may monitor the PDCCH based on the determined control resource set #0 and search space #0.

[0117] If the control unit 120 successfully decodes the PDCCH with the CRC scrambled by the SI-RNTI, the control unit 120 may attempt to receive the SI message (SIB1) based on the scheduling information carried by the PDCCH.

[0118] Here, the control unit 120 of the UE 100 may monitor the PDCCH with the CRC scrambled by the P-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 P-RNTI based on a notification of the reception of a message for an acknowledgment to the SIB1 request (message 1) from the MAC layer. If the control unit 120 successfully decodes the PDCCH with the CRC scrambled by the P-RNTI, the control unit 120 may receive a notification of an update of the system information message based on a short message. Furthermore, the control unit 120 may attempt to receive the SI message (SIB1) based on receiving the notification of the update of the system information message. For example, the control unit 120 may attempt to receive the SI message (SIB1) from the start of the modification period next after receiving the notification of the update of the system information message.

[0119] Step S205: The transmitter 211 of the base station 200 transmits an SI message including the on-demand SIB1 from the cell C2 to the UE 100. The receiver 112 of the UE 100 receives the SI message including the on-demand SIB1 from the cell C2. As a result, the receiver 112 receives the on-demand SIB1. This step may correspond to step S105. Note that the SIB1 (SI message) may be carried by the physical downlink shared channel (PDSCH).

[0120] (Third Operation Example) A third operation example will be described with reference to Fig. 8. Previously described explanations may be omitted. In this operation example, the operation from requesting on-demand SIB1 to acquiring on-demand SIB1 will be mainly described. In this operation example, a request for on-demand SIB1 is made by message 3. This operation example may be executed in the first operation example.

[0121] Step S301: 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 in the cell C2 from the UE 100. This step may correspond to step S104.

[0122] The transmitter 111 may transmit message 1 to cell C2 based on the SIB1 request setting.

[0123] Step S302: 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.

[0124] Note that the receiving unit 112 of the UE 100 may receive the message 2 in the same manner as in steps S202 and S203.

[0125] Step S303: 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 in the cell C2 from the UE 100. This step may correspond to step S104.

[0126] 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. The other SIB may be referred to as an SIBX. Message 3 may be a message that jointly requests on-demand SIB1 and SIBX.

[0127] Step S304: 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.

[0128] Message 4 may be an acknowledgment message to message 3 .

[0129] Steps S305 and S306: correspond to steps S205 and S206.

[0130] If the receiving unit 112 of the UE 100 has requested another SIB, the receiving unit 112 may receive an SI message including the SIBX in addition to the SI message including the on-demand SIB1. The UE 100 may receive an SI message including the on-demand SIB1 and the SIBX.

[0131] (Fourth Operation Example) A fourth operation example will be described with reference to FIG. 9. The previous description may be omitted. The description of cell C3 is the same as that of the first operation example, and therefore will be omitted. In this operation example, a case will be described in which UE 100 fails to receive on-demand SIB1.

[0132] Step S401: As in step S101, the transmission unit 211 of the base station 200 transmits the SIB1 request configuration from the cell C1 to the UE 100. The reception unit 112 of the UE 100 receives the SIB1 request configuration from the cell C1.

[0133] The SIB1 request configuration may include duration information regarding a waiting period until receiving an acknowledgment for the request, where the acknowledgment may be, for example, at least one of (a) a PDCCH with a CRC scrambled by the SI-RNTI or P-RNTI, (b) a PDSCH carrying the on-demand SIB1, (c) a PDCCH with a CRC scrambled by the RA-RNTI, (d) a message 2 that is a response to a message 1 for an on-demand SIB1 request, (e) a message 4 that is a response to a message 3 for an on-demand SIB1 request, and (f) an SI message that includes the on-demand SIB1.

[0134] The period information may include, for example, a timer value used to time the waiting period. The period information may include information used to calculate the period based on the modification period and / or the period of the SS burst set. The period information may include, for example, information indicating the number (e.g., multiple) of the modification period and / or the period of the SS burst set.

[0135] The SIB1 request setting may include retransmission information regarding retransmission of the on-demand SIB1 request. The retransmission information may include at least one of retransmission count information for setting the maximum number of retransmissions of the on-demand SIB1 request and retransmission power information for setting transmission power when the on-demand SIB1 request is retransmitted. The retransmission power information may be information for setting power ramping.

[0136] Steps S402 to S404: correspond to steps S102 to S104.

[0137] Step S405: The control unit 120 of the UE 100 determines a waiting period based on the period information. The control unit 120 may determine the waiting period based on the modification period and / or the period of the SS burst set in addition to the period information. The control unit 120 may determine a timer value based on the period information as the waiting period. The control unit 120 may start a timer (hereinafter, a waiting timer) to which a timer value used to measure the waiting period is set.

[0138] Step S406: The transmitter 211 of the base station 200 broadcasts the on-demand SIB1 from the cell C2 in response to the request from the UE 100. This step corresponds to step S105. However, in this operation example, the description will proceed assuming that the receiver 112 of the UE 100 cannot receive the on-demand SIB1 from the cell C2.

[0139] If the control unit 120 of the UE 100 receives a positive response before the waiting period has elapsed, the control unit 120 may determine (or may consider) that the request for the on-demand SIB1 has been successful. The control unit 120 may stop the waiting timer.

[0140] Step S407: The control unit 120 of the UE 100 determines that the waiting period has elapsed. The control unit 120 determines that the waiting period has elapsed, for example, based on the expiration of a waiting timer. If the waiting period has elapsed, the control unit 120 may determine (or may consider) that the request for the on-demand SIB1 has failed. If the request for the on-demand SIB1 has failed, the control unit 120 may execute the process of step S409.

[0141] For example, the control unit 120 of the UE 100 may determine that the request for the on-demand SIB1 has failed if, for example, it is unable to receive (a) a PDCCH with a CRC scrambled by the SI-RNTI as an acknowledgment before the elapse of the elapsed period. The control unit 120 of the UE 100 may determine that the request for the on-demand SIB1 has failed if, for example, it is unable to receive (b) a PDSCH carrying the on-demand SIB1 as an acknowledgment before the elapse of the elapsed period. The control unit 120 of the UE 100 may determine that the request for the on-demand SIB1 has failed if, for example, it is unable to receive (c) a PDCCH with a CRC scrambled by the RA-RNTI and (d) a message 2 that is a response to the message 1 for the on-demand SIB1 request as an acknowledgment before the elapse of the elapsed period. The control unit 120 of the UE 100 may determine that the request for the on-demand SIB1 has failed if it is unable to receive, as a positive response, (e) message 4 that is a response to the message 3 for the on-demand SIB1 request, before the elapse of ... UE 100. The control unit 120 of the UE 100 may determine that the request for the on-demand SIB1 has failed if it is unable to receive, as a positive response, (f) an SI message including the on-demand SIB1, before the elapse of the elapse of the elapse of the elapse of the elapse of the elapse of the elapse of the

[0142] When the waiting period has elapsed, the control unit 120 may execute the process of step S408. When the SIB1 request setting includes retransmission information, for example, the control unit 120 may execute the process of step S408. When the SIB1 request setting does not include retransmission information, the control unit 120 may omit the process of step S408.

[0143] Step S408: The transmitter 111 of the UE 100 retransmits the on-demand SIB1 request to the cell C2. The receiver 212 of the base station 200 receives the on-demand SIB1 request from the UE 100 in the cell C2.

[0144] The control unit 120 may determine the transmission power based on the retransmission power information. The control unit 120 may retransmit the on-demand SIB1 request to the cell C2 at the transmission power based on the retransmission power information.

[0145] The control unit 120 may perform the operation of step S405. If the control unit 120 does not receive the on-demand SIB1 before the waiting period has elapsed, the control unit 120 may retransmit the request for the on-demand SIB1. If the number of times the on-demand SIB1 request has been transmitted exceeds the maximum number of retransmissions, the control unit 120 may consider the request for the on-demand SIB1 to have failed. If the request for the on-demand SIB1 has failed, the control unit 120 may perform the process of step S409.

[0146] Step S409: The control unit 120 of the UE 100 may execute control to acquire a new SIB request configuration from the cell C1. As a result, the reception unit 112 of the UE 100 receives the on-demand SIB1 request configuration from the cell C1.

[0147] Step S410: The transmitter 111 of the UE 100 transmits a request for the on-demand SIB1 to the cell C2 based on the new SIB1 request setting. The receiver 212 of the base station 200 receives the request for the on-demand SIB1 from the UE 100 in the cell C2.

[0148] Step S410: corresponds to step S105.

[0149] As described above, the transmitter 211 of the base station 200 may transmit, from the first cell to the UE 100, an SIB1 request configuration related to a configuration for requesting the second cell supporting the on-demand SIB1. The SIB1 request configuration may include period information related to a waiting period until an acknowledgment for the request is received. The receiver 112 may receive, from the first cell, an SIB1 request configuration related to a configuration for requesting the on-demand SIB1 from the second cell supporting the on-demand SIB1. The transmitter 111 may transmit a request for the on-demand SIB1 to the second cell based on the SIB1 request configuration. The controller 120 may determine the waiting period based on the period information included in the SIB1 request configuration and related to a waiting period until an acknowledgment for the request is received. As a result, the UE 100 can determine that the request for the on-demand SIB1 has failed if it does not receive an acknowledgment until the determined waiting period has elapsed. As a result, it is possible to prevent the UE 100 from continuously attempting to receive the on-demand SIB 1, and to appropriately acquire the on-demand SIB 1. Furthermore, the network can control the waiting period of the UE 100 by using the period information.

[0150] Furthermore, the period information may indicate a waiting period until a PDCCH including a CRC scrambled by the SI-RNTI is received from the second cell as an acknowledgment. The receiving unit 112 may receive the on-demand SIB1 from the second cell based on the scheduling information carried by the PDCCH. As a result, if the UE 100 has successfully received the scheduling information by the end of the waiting period, the UE 100 can determine that the request for the on-demand SIB1 has been successful.

[0151] The period information may also indicate a waiting period until the UE 100 receives a physical downlink shared channel (PDSCH) carrying the on-demand SIB1 from the second cell as an acknowledgment. This allows the UE 100 to understand that the request for the on-demand SIB1 has failed if the UE 100 cannot receive the on-demand SIB1 within the waiting period.

[0152] Furthermore, the period information may indicate a waiting period until a PDCCH including a CRC scrambled by the RA-RNTI is received from the second cell as an acknowledgment. The receiving unit 112 may receive the on-demand SIB1 from the second cell based on the scheduling information carried by the PDCCH. As a result, if the UE 100 has successfully received the scheduling information by the waiting period, the UE 100 can determine that the request for the on-demand SIB1 has been successful.

[0153] Furthermore, the transmitter 111 may transmit a request for the on-demand SIB1 to the second cell by a message 1 in the random access procedure. The period information may indicate a waiting period until a message 2, which is a response to the message 1, is received from the second cell as an acknowledgment. As a result, if the UE 100 has successfully received the message 2 by the end of the waiting period, the UE 100 can recognize that the request for the on-demand SIB1 has been successful.

[0154] In addition to the period information, the control unit 120 may determine the waiting period based on at least one of a modification period in which the content of the system information of the second cell may be changed and a period of a synchronization signal (SS) burst set configured by synchronization signal blocks (SS blocks). In this way, when the control unit 120 determines the waiting period based on the modification period, it is possible to prevent the UE 100 from waiting to receive the on-demand SIB1 across the boundary between the transmission period of the on-demand SIB1 before the content is changed and the transmission period of the on-demand SIB1 after the content is changed.

[0155] Furthermore, if the transmission unit 111 does not receive the on-demand SIB1 before the waiting period has elapsed, the transmission unit 111 may retransmit the request for the on-demand SIB1. This allows the UE 100 to acquire the on-demand SIB1 even if the request for the on-demand SIB1 has failed.

[0156] The SIB1 request configuration may also include at least one of information for setting the maximum number of retransmissions of the on-demand SIB1 request and information for setting the transmission power for retransmission of the on-demand SIB1 request, thereby enabling the network to control retransmission of the on-demand SIB1 request.

[0157] Furthermore, if the control unit 120 does not receive the on-demand SIB1 before the waiting period has elapsed, the control unit 120 may execute control to acquire a new SIB1 request configuration from the first cell. This allows the UE 100 to request the on-demand SIB1 based on the latest SIB1 request configuration. This prevents the request for the on-demand SIB1 from failing due to the past SIB1 request configuration, making it easier to successfully receive the on-demand SIB1.

[0158] (Fifth Operation Example) A fifth operation example will be described with reference to FIG. 10. Previously described explanations may be omitted. The explanation for cell C3 is the same as that for the first operation example, and therefore will be omitted. In this operation example, a case will be described in which UE 100 requests SIBX from cell C2. Note that the control unit 120 of UE 100 may control the transmission unit 111 to perform the following operations.

[0159] Step S501: The transmitting unit 211 of the base station 200 transmits an SIB1 request configuration from the cell C1 to the UE 100. The receiving unit 112 of the UE 100 receives the SIB1 request configuration from the cell C1.

[0160] The SIB1 request configuration may include uplink resource information used to transmit the request for the on-demand SIB1, which may be referred to as first uplink resource information.

[0161] Steps S502 to S504: Corresponds to steps S102 to S104. Note that the transmitter 111 of the UE 100 transmits a request for the on-demand SIB1 to the cell C2 using the radio resource based on the first uplink resource information.

[0162] Step S505: The transmitting unit 211 of the base station 200 broadcasts the on-demand SIB1 from the cell C2 in response to the request from the UE 100. The receiving unit 112 of the UE 100 receives the on-demand SIB1 from the cell C2.

[0163] The on-demand SIB1 includes information on the configuration for requesting the SIBX of the second cell (hereinafter, SIBX request configuration). The SIBX request configuration may include uplink resource information used for transmitting the SIBX request (appropriately referred to as second uplink resource information). The second uplink resource information may include, for example, information indicating the configuration of resources for Message 1 used by the UE 100 to request the SIBX or an SI message for the SIBX (for example, si-RequestConfig).

[0164] Step S506: The transmitter 111 of the UE 100 transmits a SIBX request (hereinafter referred to as an on-demand SIBX request) to the cell C2 based on the SIB1X request setting. The receiver 212 of the base station 200 receives the SIBX request from the UE 100 in the cell C2.

[0165] After receiving the on-demand SIB1 from the second cell, the control unit 120 of the UE 100 may control the transmission of a SIBX request to the second cell using radio resources based on the second uplink resource information included in the on-demand SIB1.

[0166] Step S507: The transmitting unit 211 of the base station 200 broadcasts the SIBX from the cell C2 in response to the request from the UE 100. The receiving unit 112 of the UE 100 receives the SIBX from the cell C2.

[0167] As described above, the transmitter 211 may transmit, from the first cell to the UE 100, an SIB1 request configuration related to a configuration for requesting the second cell supporting the on-demand SIB1. The SIB1 request configuration may be used by the UE 100 to acquire other system information blocks (SIBs) of the second cell that are different from the on-demand SIB1. The receiver 112 may receive, from the first cell, an SIB1 request configuration related to a configuration for requesting the on-demand SIB1 from the second cell that supports the on-demand SIB1. The controller 120 may perform control to acquire other system information blocks (SIBs) of the second cell that are different from the on-demand SIB1, based on the SIB1 request configuration. As a result, the UE 100 performs an operation to acquire other SIBs based on the SIB1 request configuration, allowing the network 10 to control the acquisition of other SIBs and making it possible to appropriately acquire other SIBs of the second cell.

[0168] Furthermore, the SIB1 request configuration may include first uplink resource information used to transmit the request for the on-demand SIB1. The control unit 120 may control to transmit the request for the on-demand SIB1 to the first cell or the second cell using radio resources based on the first uplink resource information. After receiving the on-demand SIB1 from the first cell or the second cell, the control unit 120 may control to transmit a request for another SIB to the second cell using radio resources based on the second uplink resource information included in the on-demand SIB1. This allows the UE 100 to request SIBX as in the conventional case, thereby reducing the impact on existing systems.

[0169] (Sixth Operation Example) A sixth operation example will be described with reference to FIG. 11 . Previous descriptions may be omitted. In this operation example, similar to the fifth operation example, a case will be described in which the UE 100 requests SIBX from the cell C2. The UE 100 requests SIBX from the cell C2 regardless of reception of the on-demand SIB1. Note that the control unit 120 of the UE 100 may control the transmission unit 111 to perform the following operations.

[0170] Step S601: The transmitting unit 211 of the base station 200 transmits an SIB1 request configuration from the cell C1 to the UE 100. The receiving unit 112 of the UE 100 receives the SIB1 request configuration from the cell C1.

[0171] The SIB1 request configuration may include first uplink resource information used to transmit the on-demand SIB1 request and second uplink resource information used to transmit the SIBX request. The second uplink resource information may include radio resource information corresponding to each of the multiple SIBs subsequent to SIB2 that constitute the other SIBs.

[0172] Steps S602 to S604: Corresponds to steps S102 to S104. The transmitter 111 of the UE 100 transmits a request for the on-demand SIB1 to the cell C2 using the radio resource based on the first uplink resource information.

[0173] Step S605: The transmitter 111 of the UE 100 transmits a SIBX request to the cell C2 based on the SIBX request setting. The receiver 212 of the base station 200 receives the SIBX request from the UE 100 in the cell C2.

[0174] The control unit 120 controls to transmit a SIBX request to the second cell using radio resources based on the second uplink resource information. The control unit may control to transmit a specific SIBX request to the second cell using radio resources based on radio resource information corresponding to a specific SIBX requested by the UE 100 among multiple SIBXs. The control unit 120 may control to transmit the SIBX request without waiting for reception of the on-demand SIB1. Therefore, the UE 100 may transmit the on-demand SIB1 request and the SIBX request in parallel.

[0175] Note that steps S604 and S605 may request on-demand SIB1 and / or SIBX, similar to the second operation example.

[0176] Step S606: Corresponds to step S506. In this operation example, the on-demand SIB1 does not need to include the SIBX request setting.

[0177] Step S607: Corresponds to step S507.

[0178] As described above, the SIB1 request configuration may include first uplink resource information used to request the on-demand SIB1 and second uplink resource information used to request the other SIB. The control unit 120 may control to transmit the request for the other SIB to the second cell using radio resources based on the second uplink resource information. This allows the UE 100 to request the other SIB separately from the on-demand SIB1.

[0179] Furthermore, the second uplink resource information may include radio resource information corresponding to each of a plurality of SIBs subsequent to SIB2 constituting the other SIBs. The control unit 120 may perform control so that a request for the specific SIB is transmitted to the first cell or the second cell using radio resources based on radio resource information corresponding to a specific SIB requested by the UE 100 among the plurality of SIBs. This enables the UE 100 to individually request other SIBs apart from the on-demand SIB1.

[0180] (Seventh Operation Example) A seventh operation example will be described with reference to FIG. 12 . Previous descriptions may be omitted. In this operation example, similar to the fifth operation example, a case will be described in which the UE 100 requests SIBX from the cell C2. The UE 100 requests the on-demand SIB1 and SIBX together from the cell C2. Note that the control unit 120 of the UE 100 may control the transmission unit 111 to perform the following operations.

[0181] Step S701: The transmitting unit 211 of the base station 200 transmits an SIB1 request configuration from the cell C1 to the UE 100. The receiving unit 112 of the UE 100 receives the SIB1 request configuration from the cell C1.

[0182] The SIB1 request configuration may include uplink resource information used for the random access procedure in which one message requesting on-demand SIB1 and SIBX is transmitted. The uplink resource information may include, for example, information (e.g., SI-SchedulingInfo) containing information necessary for requesting on-demand SIB1 or an SI message for on-demand SIB1.

[0183] Steps S702 to S703: correspond to steps S102 to S103.

[0184] Step S704: The transmitter 111 of the UE 100 transmits one message requesting the on-demand SIB1 and the SIBX to the cell C2 using radio resources based on the uplink resource information. The controller 120 may control the UE 100 to request the on-demand SIB1 and the other SIBs together from the cell C2 based on the SIB1 request setting. For example, the controller 120 may control the UE 100 to transmit one message requesting the on-demand SIB1 and the other SIBs to the cell C2. The one message may be message 3 in the random access procedure.

[0185] In addition, step S704 may request on-demand SIB1 and SIBX, similar to the third operation example.

[0186] Step S705: The transmitter 211 of the base station 200 transmits the on-demand SIB1 and the SIBX from the cell C2 to the UE 100. The transmitter 211 may transmit an SI message including the on-demand SIB1 and the SIBX together. The receiver 112 of the UE 100 transmits the on-demand SIB1 and the SIBX from the cell C2 to the UE 100.

[0187] As described above, the control unit 120 of the UE 100 may perform control so as to request the on-demand SIB1 and other SIBs together from the first cell or the second cell based on the SIB1 request setting. This allows the UE 100 to request multiple SIBs together in one message, thereby reducing the number of signalings between the UE 100 and the base station 200.

[0188] The SIB1 request configuration may also include uplink resource information used in a random access procedure in which one message requesting the on-demand SIB1 and other SIBs is transmitted. The control unit 120 may control to transmit one message requesting the on-demand SIB1 and other SIBs to the second cell. This allows multiple SIBs to be requested collectively in one message in the random access procedure, making it possible to acquire multiple SIBs without transitioning to the RRC connected state, for example.

[0189] (Eighth Operation Example) An eighth operation example will be described with reference to FIG. 13. Previously described explanations may be omitted. The explanation for cell C3 is the same as that for the first operation example, and therefore will be omitted. In this operation example, a case will be described in which UE 100 requests SIBX from cell C1. Note that the control unit 120 of UE 100 may control the transmission unit 111 to perform the following operations.

[0190] Step S801: The transmitting unit 211 of the base station 200 transmits an SIB1 request configuration from the cell C1 to the UE 100. The receiving unit 112 of the UE 100 receives the SIB1 request configuration from the cell C1.

[0191] The SIB1 request configuration may include first uplink resource information used to transmit a request for on-demand SIB1 of cell C2 to cell C1, which is the first cell.

[0192] Steps S802 to S803: correspond to steps S602 to S603.

[0193] Step S804: The transmitter 111 of the UE 100 transmits a request for the on-demand SIB1 of the cell C2 to the cell C1 by using the radio resource based on the first uplink resource information. The receiver 212 of the base station 200 receives the request for the on-demand SIB1 from the UE 100 in the cell C1.

[0194] Step S805: The transmitting unit 211 of the base station 200 broadcasts the on-demand SIB1 from the cell C1 in response to the request from the UE 100. The receiving unit 112 of the UE 100 receives the on-demand SIB1 from the cell C1.

[0195] The on-demand SIB1 is the SIB1 of cell C2. The on-demand SIB1 includes information about a setting for requesting the SIBX of cell C2 (hereinafter, SIBX request setting). The SIBX request setting may include second uplink resource information used for transmitting the SIBX request.

[0196] Step S806: The transmitter 111 of the UE 100 transmits a SIB1X request for the cell C2 to the cell C1 based on the SIB1X request setting. The receiver 212 of the base station 200 receives the SIBX request from the UE 100 in the cell C1.

[0197] After receiving on-demand SIB1 from cell C1, the control unit 120 of UE100 may control the transmission of a SIBX request to cell C1 using radio resources based on the second uplink resource information included in the on-demand SIB1.

[0198] Step S807: The transmitting unit 211 of the base station 200 broadcasts the SIBX from the cell C1 in response to the request from the UE 100. The receiving unit 112 of the UE 100 receives the SIBX from the cell C1.

[0199] Thereafter, the control unit 230 of the UE 100 may perform initial access to the cell C2, for example, based on the on-demand SIB1 and SIBX received from the cell C1.

[0200] As described above, the receiving unit 212 of the base station 200 may receive from the UE 100 a request for the on-demand SIB1 transmitted using the radio resources based on the first uplink resource information. The transmitting unit 211 may transmit to the UE 100, based on the request for the on-demand SIB1, the on-demand SIB1 including second uplink resource information indicating the radio resources used for the request for the other SIB. The transmitting unit 211 may transmit to the UE 100, based on the request for the other SIB transmitted using the radio resources based on the second uplink resource information. The control unit 120 of the UE 100 may control the transmission of the request for the on-demand SIB1 to the first cell using the radio resources based on the first uplink resource information. As a result, the UE 100 performs an operation to acquire the other SIB based on the SIB1 request setting, and the network 10 can control the acquisition of the other SIB, thereby enabling the other SIB of the second cell to be appropriately acquired.

[0201] (Ninth Operation Example) A ninth operation example will be described with reference to FIG. 14 . Previous descriptions may be omitted. In this operation example, similar to the eighth operation example, a case will be described in which the UE 100 requests SIBX from the cell C1. Similar to the sixth operation example, the UE 100 requests SIBX from the cell C1 regardless of reception of on-demand SIB1. Note that the control unit 120 of the UE 100 may control the transmission unit 111 to perform the following operations.

[0202] Step S901: The transmitting unit 211 of the base station 200 transmits an SIB1 request configuration from the cell C1 to the UE 100. The receiving unit 112 of the UE 100 receives the SIB1 request configuration from the cell C1.

[0203] The SIB1 request configuration may include first uplink resource information used to transmit a request for the on-demand SIB1 of cell C2 to cell C1 and second uplink resource information used to transmit a request for the SIBX of cell C2 to cell C1. The second uplink resource information may include radio resource information corresponding to each of the multiple SIBs subsequent to SIB2 that constitute the other SIBs.

[0204] Steps S902 to S903: correspond to steps S102 to S103.

[0205] Step S904: corresponds to step S804.

[0206] Step S905: The transmitter 111 of the UE 100 transmits a SIBX request to the cell C1 based on the SIBX request setting. The receiver 212 of the base station 200 receives the SIBX request from the UE 100 in the cell C1.

[0207] The control unit 120 controls to transmit a SIBX request to the cell C1 using radio resources based on the second uplink resource information. The control unit may control to transmit a specific SIBX request to the cell C1 using radio resources based on radio resource information corresponding to a specific SIBX requested by the UE 100 among multiple SIBXs. The control unit 120 may control to transmit the SIBX request without waiting for reception of the on-demand SIB1. Therefore, the UE 100 may transmit the on-demand SIB1 request and the SIBX request in parallel.

[0208] Step S906: corresponds to step S506. In this operation example, the on-demand SIB1 does not need to include the SIBX request setting.

[0209] Step S907: corresponds to step S507.

[0210] Thereafter, the control unit 230 of the UE 100 may perform initial access to the cell C2, for example, based on the on-demand SIB1 and SIBX received from the cell C1.

[0211] As described above, the SIB1 request configuration may include first uplink resource information used to request the on-demand SIB1 and second uplink resource information used to request the other SIB. The receiving unit 212 of the base station 200 may receive the request for the other SIB from the UE 100 using the radio resource based on the second uplink resource information. The control unit 120 of the UE 100 may control to transmit the request for the other SIB to the second cell using the radio resource based on the second uplink resource information. This enables the UE 100 to request the other SIB separately from the on-demand SIB1.

[0212] Furthermore, the second uplink resource information may include radio resource information corresponding to each of the multiple SIBs from SIB2 onward that constitute the other SIBs. The receiving unit 212 of the base station 200 may receive a request for the specific SIB from the UE 100 using radio resources based on radio resource information corresponding to the specific SIB requested by the UE 100 among the multiple SIBs. This enables the UE 100 to individually request the other SIBs apart from the on-demand SIB1.

[0213] (Tenth Operation Example) A tenth operation example will be described with reference to FIG. 15 . Previous descriptions may be omitted. In this operation example, similar to the fifth operation example, a case will be described in which the UE 100 requests SIBX from the cell C1. Similar to the seventh operation example, the UE 100 requests the on-demand SIB1 and SIBX together from the cell C1. Note that the control unit 120 of the UE 100 may control the transmission unit 111 to perform the following operations.

[0214] Step S1001: The transmitting unit 211 of the base station 200 transmits an SIB1 request configuration from the cell C1 to the UE 100. The receiving unit 112 of the UE 100 receives the SIB1 request configuration from the cell C1.

[0215] The SIB1 request configuration may include uplink resource information used for the random access procedure in which one message is transmitted to cell C1 requesting on-demand SIB1 and SIBX of cell C2. The uplink resource information may include, for example, information (e.g., SI-SchedulingInfo) including information necessary to request on-demand SIB1 or an SI message for SIB1 of cell C2 from cell C1.

[0216] Steps S1002 to S1003: correspond to steps S102 to S103.

[0217] Step S1004: The transmitter 111 of the UE 100 transmits one message requesting the on-demand SIB1 and the SIBX to the cell C1 using radio resources based on the uplink resource information. The controller 120 may control the UE 100 to request the on-demand SIB1 and the other on-demand SIBs together from the cell C1 based on the SIB1 request setting. For example, the controller 120 may control the UE 100 to transmit one message requesting the on-demand SIB1 and the other SIBs to the cell C1. The one message may be message 3 in the random access procedure.

[0218] In addition, step S1004 may request on-demand SIB1 and SIBX, similar to the third operation example.

[0219] Step S1005: The transmitter 211 of the base station 200 transmits the on-demand SIB1 and the SIBX from the cell C1 to the UE 100. The transmitter 211 may transmit an SI message including the on-demand SIB1 and the SIBX together. The receiver 112 of the UE 100 transmits the on-demand SIB1 and the SIBX from the cell C1 to the UE 100.

[0220] Thereafter, the control unit 230 of the UE 100 may perform initial access to the cell C2, for example, based on the on-demand SIB1 and SIBX received from the cell C1.

[0221] As described above, the SIB1 request configuration may include uplink resource information used in a random access procedure in which one message requesting the on-demand SIB1 and other SIBs is transmitted. The receiver 212 of the base station 200 may receive one message requesting the on-demand SIB1 and other SIBs from the UE 100. The controller 120 of the UE 100 may control to transmit one message requesting the on-demand SIB1 and other SIBs to the first cell. This allows multiple SIBs to be requested collectively in one message in the random access procedure, making it possible to acquire multiple SIBs without transitioning to an RRC connected state, for example.

[0222] (Eleventh Operation Example) An eleventh operation example will be described with reference to Fig. 16. Previous descriptions may be omitted. In this operation example, a case where the UE 100 determines the transmission method will be described.

[0223] Step S1101: The control unit 120 of the UE 100 determines whether the SIB1 request configuration includes specific resource information. The specific resource information may be, for example, radio resource information corresponding to each of a plurality of SIBs. The specific resource information may be information (e.g., si-RequestConfig) indicating a resource configuration for Message 1 used by the UE 100 to request the on-demand SIB1 or an SI message for the on-demand SIB1. The specific resource information may be included in information (e.g., SI-SchedulingInfo) including information necessary for requesting the on-demand SIB1 or an SI message for the on-demand SIB1.

[0224] If the SIB1 request configuration includes specific resource information, the control unit 120 may execute the process of step S1102. On the other hand, if the SIB1 request configuration does not include specific resource information, the control unit 120 may execute the process of step S1103. Based on the SIB1 request configuration, the control unit 120 may determine a transmission method for transmitting a request for another SIB to cell C1 or cell C2 as follows.

[0225] Step S1102: The control unit 120 determines, as a transmission method, a method of transmitting a request from a specific SIBX to cell C1 or C2 using radio resources based on specific resource information corresponding to a specific SIBX among multiple SIBXs requested by the UE 100. The control unit 120 controls to transmit the SIBX request, for example, as in the sixth operation example.

[0226] Step S1103: The control unit 120 determines a method for transmitting a request for a specific SIBX to cell C1 or C2 using radio resources based on uplink resource information other than the specific resource information. For example, the control unit 120 controls to transmit the request for the SIBX using radio resources based on uplink resource information used in a random access procedure in which one message requesting the on-demand SIB1 and the SIBX is transmitted.

[0227] As described above, the control unit 120 of the UE 100 may determine a transmission method for transmitting a request for another SIB to the first cell or the second cell based on the SIB1 request setting. This allows the UE 100 to determine an appropriate transmission method for the SIB request from among a plurality of transmission methods.

[0228] Furthermore, when the SIB1 request configuration includes radio resource information corresponding to each of a plurality of SIBs, the control unit 120 may determine, as a transmission method, a method of transmitting the SIBX request to the first cell or the second cell using radio resources based on radio resource information corresponding to the SIBX requested by the UE 100 among the plurality of SIBs. This enables the UE 100 to transmit the SIBX request in parallel with the on-demand SIB1 request.

[0229] Furthermore, when the SIB1 request configuration does not include radio resource information corresponding to each of the plurality of SIBs and the SIB1 request configuration includes uplink resource information used in a random access procedure in which one message requesting the on-demand SIB1 and SIBX is transmitted, the control unit 120 may determine, as the transmission method, a method of transmitting one message requesting the on-demand SIB1 and SIBX to the first cell or the second cell. This allows the UE 100 to request multiple SIBs collectively in one message, thereby reducing the number of signalings between the UE 100 and the base station 200.

[0230] (Other embodiments) In the above-described first to fourth operation examples, the case where the UE 100 requests the SIB1 of the cell C2 from the cell C2 has been described as an example, but this is not limited thereto. In the first to fourth operation examples, similar to the eighth to tenth operation examples, the UE 100 may request the SIB1 of the cell C2 from the cell C1.

[0231] In the above-described embodiment, the SIB1 request configuration may be, for example, a plurality of configurations (e.g., a second SIB1 request configuration) for requesting an on-demand SIB1, which may be defined in advance in a specification. The base station 200 may transmit to the UE 100 an SIB1 request configuration (first SIB1 request configuration) including information specifying one of the plurality of configurations. The UE 100 may apply the specified SIB1 request configuration based on the specifying information.

[0232] In the above-described embodiment, an NR-based mobile communication system has been described as an example of the mobile communication system 11. However, the mobile communication system 11 is not limited to this example. The mobile communication system 11 may be a system compliant with the TS of either LTE (Long Term Evolution) or another generation system (e.g., 6th generation) of the 3GPP standard. The base station 200 may be an eNB that provides E-UTRA user plane and control plane protocol termination toward the UE 100 in LTE. The mobile communication system 11 may be a system compliant with 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).

[0233] 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)).

[0234] 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.

[0235] 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 modifications within the scope of equivalents. 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.

[0236] (Additional Notes) Additional notes will be given regarding the features of the above-described embodiment.

[0237] (Supplementary Note 1) A communications device comprising: a receiver (112) that receives system information from a serving cell, the system information including information regarding a configuration for requesting an on-demand system information block type 1 (SIB1); and a controller (120), wherein the information regarding the configuration for requesting the on-demand SIB1 includes one or more physical cell identifiers and information indicating time and frequency resources of a Physical Random Access Channel (PRACH) corresponding to each of the one or more physical cell identifiers, and the controller controls to transmit the request for the on-demand SIB1 to a cell identified by any of the one or more physical cell identifiers, using PRACH resources indicated based on the information indicating the time and frequency resources of the PRACH. (Supplementary Note 2) The communications device according to Supplementary Note 1, wherein the information regarding the configuration for requesting the on-demand SIB1 includes information for setting uplink subcarrier spacing, and the controller controls to transmit the request for the on-demand SIB1 to a cell identified by any of the one or more physical cell identifiers based on the information for setting uplink subcarrier spacing. (Supplementary Note 3) The communication device according to Supplementary Note 1 or 2, wherein the information on the configuration for requesting the on-demand SIB1 includes information for setting a position and a bandwidth of an uplink bandwidth portion (BWP) in the frequency domain, and the controller controls to transmit the request for the on-demand SIB1 to a cell identified by any of the one or more physical cell identifiers based on the information for setting the position and bandwidth of the uplink BWP in the frequency domain. (Supplementary Note 4) The communication device according to any one of Supplementary Notes 1 to 3, wherein the information on the configuration for requesting the on-demand SIB1 includes at least one of information indicating a number of transmissions of the on-demand SIB1, information indicating a transmission cycle of the on-demand SIB1, and information indicating a transmission period of the on-demand SIB1, and the controller controls to receive the on-demand SIB1 based on at least one of the information indicating the number of transmissions of the on-demand SIB1, information indicating the transmission cycle of the on-demand SIB1, and information indicating the transmission period of the on-demand SIB1.(Supplementary Note 5) A base station comprising: a transmitter (211) that transmits system information including information regarding a configuration for requesting an on-demand system information block type 1 (SIB1) to a communication device, wherein the information regarding the configuration for requesting the on-demand SIB1 includes one or more physical cell identifiers and information indicating time and frequency resources of a Physical Random Access Channel (PRACH) corresponding to each of the one or more physical cell identifiers, and the information indicating the time and frequency resources of the PRACH indicates PRACH resources for the communication device to transmit a request for the on-demand SIB1 to a cell identified by any of the one or more physical cell identifiers. (Supplementary Note 6) The base station according to Supplementary Note 5, wherein the information regarding the configuration for requesting the on-demand SIB1 includes information for setting uplink subcarrier spacing, and the information for setting uplink subcarrier spacing is used by the communication device to transmit the request for the on-demand SIB1 to a cell identified by any of the one or more physical cell identifiers. (Supplementary Note 7) The base station according to Supplementary Note 5 or 6, wherein the information on the configuration for requesting the on-demand SIB1 includes information for setting a position and a bandwidth of an uplink bandwidth portion (BWP) in the frequency domain, and the information for setting the position and bandwidth of the uplink BWP in the frequency domain is used by the communication device to transmit the request for the on-demand SIB1 to a cell identified by any of the one or more physical cell identifiers. (Supplementary Note 8) The communication device according to any one of Supplementary Notes 5 to 7, wherein the information on the configuration for requesting the on-demand SIB1 includes at least one of information indicating the number of transmissions of the on-demand SIB1, information indicating a transmission cycle of the on-demand SIB1, and information indicating a transmission period of the on-demand SIB1, and at least one of the information indicating the number of transmissions of the on-demand SIB1, information indicating the transmission cycle of the on-demand SIB1, and information indicating the transmission period of the on-demand SIB1 is used by the communication device to receive the on-demand SIB1.(Supplementary Note 9) A communication method executed by a communication device (100), comprising: a step of receiving system information from a serving cell, the system information including information regarding a setting for requesting an on-demand system information block type 1 (SIB1); the information regarding the setting for requesting the on-demand SIB1 includes one or more physical cell identifiers and information indicating time and frequency resources of a physical random access channel (PRACH) corresponding to each of the one or more physical cell identifiers; and a step of controlling transmission of the request for the on-demand SIB1 to a cell identified by any of the one or more physical cell identifiers using PRACH resources indicated based on the information indicating the time and frequency resources of the PRACH. (Supplementary Note 10) A communication method executed in a base station, comprising: transmitting system information to a communication device, the system information including information regarding a configuration for requesting an on-demand system information block type 1 (SIB1); the information regarding the configuration for requesting the on-demand SIB1 includes information indicating one or more physical cell identifiers and time and frequency resources of a Physical Random Access Channel (PRACH) corresponding to each of the one or more physical cell identifiers; and the information indicating the time and frequency resources of the PRACH indicates PRACH resources for the communication device to transmit a request for the on-demand SIB1 to a cell identified by any of the one or more physical cell identifiers. (Supplementary Note 11) A communication device comprising: a receiving unit that receives, from a first cell, a SIB1 request configuration related to a configuration for requesting an on-demand SIB1 from a plurality of second cells that support the system information block type 1 (on-demand SIB1) that is broadcast upon request; and a transmitting unit that transmits a request for the on-demand SIB1 to the one second cell by using uplink resource information corresponding to one second cell from uplink resource information included in the SIB1 request configuration that is used for transmitting the request corresponding to each of the plurality of second cells.

[0238] (Supplementary Note 12) The communication device according to Supplementary Note 11, wherein the SIB1 request configuration includes the uplink resource information corresponding to the plurality of second cells and a cell identifier corresponding to the uplink resource information.

[0239] (Supplementary Note 13) The communication device according to Supplementary Note 11 or 12, wherein the receiving unit receives from the first cell a list of neighboring cell information in which cell identifiers of a plurality of neighboring cells that are candidates for cell reselection are entered, and the SIB1 request configuration includes the same number of entries as the list of neighboring cell information, and the entries are listed in the same order as the list of neighboring cell information.

[0240] (Supplementary Note 14) The communication device according to any one of Supplementary Notes 11 to 13, wherein the uplink resource information includes configuration information for configuring an uplink bandwidth portion for transmitting the request.

[0241] (Supplementary Note 15) The communication device according to any one of Supplementary Notes 11 to 14, wherein the uplink resource information includes configuration information used to identify random access parameters for transmitting the request.

[0242] (Supplementary Note 16) The communication device according to any one of Supplementary Notes 11 to 15, wherein the SIB1 request configuration includes transmission information regarding transmission of the on-demand SIB1 from each of the plurality of second cells, and the receiving unit receives the on-demand SIB1 from the one second cell based on the transmission information.

[0243] (Supplementary Note 17) The communication device according to Supplementary Note 16, wherein the transmission information includes information indicating at least one of a number of times the on-demand SIB1 is to be transmitted, a transmission cycle of the on-demand SIB1, and a transmission period of the on-demand SIB1.

[0244] (Supplementary Note 18) The communication device according to any one of Supplementary Notes 11 to 17, wherein the receiving unit receives validity information from the first cell, the validity information being used to determine validity of the SIB1 request configuration; and the control unit determines whether the SIB1 request configuration corresponding to the one second cell is valid based on the validity information.

[0245] (Supplementary Note 19) The communication device according to Supplementary Note 18, wherein the control unit executes control to acquire a new SIB1 request configuration from the first cell when the SIB1 request configuration corresponding to the one second cell is not valid.

[0246] (Supplementary Note 20) A base station that manages a first cell, comprising: a transmitter that transmits, from the first cell to a communication device, a SIB1 request configuration related to a configuration for requesting an on-demand system information block type 1 (on-demand SIB1) broadcast upon request from a plurality of second cells that support the on-demand SIB1, wherein the SIB1 request configuration includes uplink resource information used for transmitting the request corresponding to each of the plurality of second cells.

[0247] (Supplementary Note 21) The base station according to Supplementary Note 20, wherein the SIB1 request configuration includes the uplink resource information corresponding to the plurality of second cells and cell identifiers of the second cells corresponding to the uplink resource information.

[0248] (Supplementary Note 22) The base station according to Supplementary Note 20 or 21, wherein the transmitter transmits a list of neighboring cell information, in which cell identifiers of a plurality of neighboring cells that are candidates for cell reselection are entered, from the first cell to the communication device, and the SIB1 request configuration includes the same number of entries as the list of neighboring cell information, and the entries are listed in the same order as the list of neighboring cell information.

[0249] (Supplementary Note 23) The base station according to any one of Supplementary Notes 20 to 22, wherein the uplink resource information includes configuration information for configuring an uplink bandwidth portion for transmitting the request.

[0250] (Supplementary Note 24) The base station according to any one of Supplementary Notes 20 to 23, wherein the uplink resource information includes configuration information used to identify random access parameters for transmitting the request.

[0251] (Supplementary Note 25) The base station according to any one of Supplementary Notes 20 to 24, wherein the SIB1 request configuration includes transmission information regarding transmission of the on-demand SIB1 from each of the plurality of second cells.

[0252] (Supplementary Note 26) The base station according to Supplementary Note 25, wherein the transmission information includes information indicating at least one of a number of times the on-demand SIB1 is transmitted, a transmission cycle of the on-demand SIB1, and a transmission period of the on-demand SIB1.

[0253] (Supplementary Note 27) The base station according to any one of Supplementary Notes 20 to 26, wherein the transmitter transmits validity information used to determine validity of the SIB1 request configuration from the first cell to the communication device.

[0254] (Supplementary Note 28) A communication method executed by a communication device, comprising: a step of receiving, from a first cell, a SIB1 request configuration regarding a configuration for requesting a system information block type 1 (on-demand SIB1) broadcast upon request from a plurality of second cells that support the on-demand SIB1; and a step of transmitting a request for the on-demand SIB1 to the one second cell by using uplink resource information corresponding to one second cell from uplink resource information included in the SIB1 request configuration and used for transmitting the request corresponding to each of the plurality of second cells.

Claims

1. A communications device comprising: a receiving unit (112) that receives system information from a serving cell, the system information including information regarding settings for requesting an on-demand system information block type 1 (SIB1); and a control unit (120), wherein the information regarding settings for requesting the on-demand SIB1 includes one or more physical cell identifiers and information indicating time and frequency resources of a physical random access channel (PRACH) corresponding to each of the one or more physical cell identifiers, and the control unit controls to transmit a request for the on-demand SIB1 to a cell identified by any of the one or more physical cell identifiers using PRACH resources indicated based on the information indicating the time and frequency resources of the PRACH.

2. The communication device of claim 1, wherein the information regarding the settings for requesting the on-demand SIB1 includes information for setting uplink subcarrier spacing, and the control unit controls to transmit a request for the on-demand SIB1 to a cell identified by any of the one or more physical cell identifiers based on the information for setting uplink subcarrier spacing.

3. The communication device according to claim 1 or 2, wherein the information regarding the settings for requesting the on-demand SIB1 includes information for setting a position and bandwidth of an uplink bandwidth portion (BWP) in the frequency domain, and the control unit controls to transmit the request for the on-demand SIB1 to a cell identified by any of the one or more physical cell identifiers based on the information for setting the position and bandwidth of the uplink BWP in the frequency domain.

4. The communication device described in claim 1 or 2, wherein the information regarding the settings for requesting the on-demand SIB1 includes at least one of information indicating the number of times the on-demand SIB1 is to be transmitted, information indicating the transmission period of the on-demand SIB1, and information indicating the transmission duration of the on-demand SIB1, and the control unit controls to receive the on-demand SIB1 based on at least one of information indicating the number of times the on-demand SIB1 is to be transmitted, information indicating the transmission period of the on-demand SIB1, and information indicating the transmission duration of the on-demand SIB1.

5. A base station comprising: a transmitter (211) for transmitting system information to a communication device, the system information including information regarding settings for requesting an on-demand system information block type 1 (SIB1), wherein the information regarding settings for requesting the on-demand SIB1 includes information indicating one or more physical cell identifiers and time and frequency resources of a physical random access channel (PRACH) corresponding to each of the one or more physical cell identifiers, and the information indicating the time and frequency resources of the PRACH indicates PRACH resources for the communication device to transmit a request for the on-demand SIB1 to a cell identified by any of the one or more physical cell identifiers.

6. The base station according to claim 5, wherein the information regarding the settings for requesting the on-demand SIB1 includes information for setting uplink subcarrier spacing, and the information for setting uplink subcarrier spacing is used by the communication device to transmit a request for the on-demand SIB1 to a cell identified by any of the one or more physical cell identifiers.

7. The base station according to claim 5 or 6, wherein the information relating to the configuration for requesting the on-demand SIB1 includes information for setting a position and a bandwidth of an uplink bandwidth portion (BWP) in the frequency domain, and the information for setting a position and a bandwidth of the uplink BWP in the frequency domain is used by the communication device to transmit a request for the on-demand SIB1 to a cell identified by any of the one or more physical cell identifiers.

8. The base station described in claim 5 or 6, wherein the information regarding the settings for requesting the on-demand SIB1 includes at least one of information indicating the number of times the on-demand SIB1 is to be transmitted, information indicating the transmission period of the on-demand SIB1, and information indicating the transmission duration of the on-demand SIB1, and at least one of the information indicating the number of times the on-demand SIB1 is to be transmitted, information indicating the transmission period of the on-demand SIB1, and information indicating the transmission duration of the on-demand SIB1 is used by the communication device to receive the on-demand SIB1.

9. A communication method executed by a communication device (100), comprising: a step of receiving system information from a serving cell, the system information including information regarding settings for requesting an on-demand system information block type 1 (SIB1); the information regarding settings for requesting the on-demand SIB1 includes one or more physical cell identifiers and information indicating time and frequency resources of a physical random access channel (PRACH) corresponding to each of the one or more physical cell identifiers; and a step of controlling transmission of the request for the on-demand SIB1 to a cell identified by any of the one or more physical cell identifiers using PRACH resources indicated based on the information indicating the time and frequency resources of the PRACH.

10. A communication method executed in a base station, comprising the step of transmitting system information including information regarding settings for requesting an on-demand system information block type 1 (SIB1) to a communication device, wherein the information regarding settings for requesting the on-demand SIB1 includes information indicating one or more physical cell identifiers and time and frequency resources of a physical random access channel (PRACH) corresponding to each of the one or more physical cell identifiers, and the information indicating the time and frequency resources of the PRACH indicates PRACH resources for the communication device to transmit a request for the on-demand SIB1 to a cell identified by any of the one or more physical cell identifiers.

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