WO2025211152A1 - Communication device, base station, and communication method - Google Patents

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 a setting for requesting an on-demand SIB1; and a control unit (120). The information relating to the setting for requesting the on-demand SIB1 includes information indicating time and frequency resources of a physical random access channel (PRACH), and information indicating a random access response window defined by the length of a slot. When the request for the on-demand SIB1 is transmitted using a PRACH resource indicated on the basis of the information indicating the time and frequency resources of the PRACH, the control unit controls to monitor the random access response, corresponding to the request of the on-demand SIB1, in a period indicated on the basis of the information indicating the random access response window.

Description

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

This application is based on and claims the benefit of priority from Patent Application No. 2024-061782, filed April 5, 2024, the entire contents of which are incorporated herein by reference.

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

3GPP (registered trademark; the same applies hereinafter) (Third Generation Partnership Project), a standardization project for mobile communications systems, is 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 in response to a request from a communication device, is being considered (see, for example, Non-Patent Document 1). Cells that support on-demand SIB1 (hereinafter referred to as "NES cells") can save energy by not having to periodically transmit SIB1.

“R1-2400600” (Discussion on the enhancement to upport on demand SIB1 for idle/inactive mode UE)

A communications device according to a first aspect includes a receiver that receives system information from a serving cell, the system information including information regarding settings for requesting an on-demand SIB1, and a controller. The information regarding settings for requesting the on-demand SIB1 includes information indicating time and frequency resources of a physical random access channel (PRACH), and information indicating a window of a random access response defined by a slot length. When the request for the on-demand SIB1 is transmitted using PRACH resources indicated based on the information indicating the time and frequency resources of the PRACH, the controller controls to monitor the random access response corresponding to the request for the on-demand SIB1 during the period indicated based on the information indicating the window of the random access response.

A base station according to a second aspect includes: a receiving unit that receives, from a communication device that has received system information including information regarding settings for requesting an on-demand SIB1, a request for the on-demand SIB1 using physical random access channel (PRACH) resources indicated based on information indicating time and frequency resources of the PRACH included in the information regarding settings for requesting the on-demand SIB1; and a transmitting unit that transmits the random access response corresponding to the request for the on-demand SIB1 during a period indicated based on information indicating a random access response window defined by the slot length included in the information regarding settings for requesting the on-demand SIB1.

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 settings for requesting an on-demand SIB1. The information regarding settings for requesting the on-demand SIB1 includes information indicating time and frequency resources of a physical random access channel (PRACH) and information indicating a window for a random access response defined by a slot length. When the request for the on-demand SIB1 is transmitted using PRACH resources indicated based on the information indicating the time and frequency resources of the PRACH, the communication method further includes a step of controlling to monitor the random access response corresponding to the request for the on-demand SIB1 during the period indicated based on the information indicating the window for the random access response.

A communication method according to a fourth aspect is a communication method executed by a base station. The communication method includes the steps of: receiving, from a communication device that has received system information including information related to settings for requesting an on-demand SIB1, a request for the on-demand SIB1, the request being transmitted using physical random access channel (PRACH) resources indicated based on information indicating time and frequency resources of the PRACH included in the information related to settings for requesting the on-demand SIB1; and transmitting the random access response corresponding to the request for the on-demand SIB1 during a period indicated based on information indicating a random access response window defined by a slot length included in the information related to settings for requesting the on-demand SIB1.

The objects, features, advantages, and other features of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.
FIG. 1 is a diagram showing a configuration of a mobile communication system according to an embodiment. FIG. 2 is a diagram illustrating an example of the configuration of a protocol stack according to the embodiment. FIG. 3 is a diagram illustrating a configuration of a UE according to the embodiment. FIG. 4 is a diagram illustrating a configuration of a base station according to the embodiment. FIG. 5 is a sequence diagram for explaining the first operation example. FIG. 6 is a diagram for explaining the first operation example. FIG. 7 is a sequence diagram for explaining the second operation example. FIG. 8 is a sequence diagram for explaining the third operation example. FIG. 9 is a sequence diagram for explaining the fourth operation example. FIG. 10 is a sequence diagram for explaining the fifth operation example. FIG. 11 is a sequence diagram for explaining the sixth operation example. FIG. 12 is a sequence diagram for explaining the seventh operation example. FIG. 13 is a sequence diagram for explaining the eighth operation example. FIG. 14 is a sequence diagram for explaining the ninth operation example. FIG. 15 is a sequence diagram for explaining the tenth operation example. FIG. 16 is a flowchart for explaining the eleventh operation example.

The mobile communication system according to the embodiment will be described with reference to the drawings. In the drawings, the same or similar parts are denoted by the same or similar reference numerals.

One of the objectives of this disclosure is to provide a communication device, base station, and communication method that enables a communication device to properly acquire the SIB of an NES cell.

(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).

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

UE100 is a communication device that communicates via base station 200. UE100 may be a device used by a user. UE100 may be a mobile device such as a mobile phone terminal such as a smartphone, a tablet terminal, a laptop PC, a communication module, or a communication card. UE100 may be a vehicle (e.g., a car, a train, etc.) or a device installed therein. UE100 may be a transport vehicle other than a vehicle (e.g., a ship, an airplane, etc.) or a device installed therein. UE100 may be a sensor or a device installed therein. Note that UE100 may be referred to by other names such as terminal, terminal device, mobile station, mobile terminal, mobile device, mobile unit, subscriber station, subscriber terminal, subscriber device, subscriber unit, wireless station, wireless terminal, wireless device, wireless unit, remote station, remote terminal, remote device, or remote unit. UE100 is an example of a terminal, and terminals may include factory equipment, etc.

NG-RAN20 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 by a cell, or a cell may be replaced by a base station 200. A cell constitutes the smallest unit of a communication area. One cell belongs to one frequency (carrier frequency). The term "cell" can refer to wireless communication resources or to a communication target of UE100. Each base station 200 can perform wireless communication with UE100 located in its own cell. The base station 200 communicates with UE100 using the RAN protocol stack. Details of the protocol stack will be described later. In addition, the base station 200 is connected to other base stations 200 (which may be referred to as neighboring base stations) via an Xn interface. The base station 200 communicates with neighboring 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).

5GC30 includes a core network device 300. The core network device 300 includes, for example, an AMF (Access and Mobility Management Function) and/or a UPF (User Plane Function). The AMF manages the mobility of the UE 100. The UPF provides functions specialized for U-plane processing. The AMF and UPF are connected to the base station 200 via an NG interface.

(Example of protocol stack configuration)
Next, an example of the configuration of a protocol stack according to this embodiment will be described with reference to FIG.

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

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 UE 100 and the PHY layer of base station 200 via a physical channel.

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 UE100 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 UE100.

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

The PDCP layer performs header compression/decompression, and encryption/decryption.

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

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

The NAS layer, which is located above the RRC layer in UE100, performs session management and mobility management for UE100. NAS signaling is transmitted between the NAS layer of UE100 and the NAS layer of the core network device 300.

In addition to the radio interface protocol, UE100 also has an application layer, etc.

(Radio frame structure)
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 in a normal CP (Cyclic Prefix) and 12 in 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.

(Configuration of user device)
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.

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 reception unit 112 may be configured to include multiple antennas and RF (Radio Frequency) circuits. The antenna converts signals into radio waves and radiates the radio waves into space. The antenna also receives radio waves in space and converts the radio waves into signals. The RF circuit performs analog processing of signals transmitted and received via the antenna. The RF circuit may include high-frequency filters, amplifiers, modulators, low-pass filters, etc.

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 programs and memory for storing the programs. The processor may execute the programs 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 RF circuit. The digital processing includes processing of the RAN protocol stack. The memory stores the programs executed by the processor, parameters related to the programs, and data related to the programs. The memory may include at least one of ROM (Read Only Memory), EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory), RAM (Random Access Memory), and flash memory. All or part of the memory may be contained within the processor.

As mentioned above, while the introduction of on-demand SIB1 as one of the NESs is being considered, there is a concern that if there are multiple cells (hereinafter sometimes referred to as second cells) that support on-demand SIB1, UE100 may not be able to properly acquire on-demand SIB1 from the target cell. In UE100 of this embodiment, the receiver 112 receives from the first cell a 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 the 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 transmitting a request for on-demand SIB1 using uplink resource information included in the SIB1 request configuration corresponding to the target second cell, and can appropriately acquire the on-demand SIB1.

Furthermore, even if UE100 fails to request on-demand SIB1, there is a concern that UE100 may continue to attempt to receive SIB1 without being able to determine whether or not the request for on-demand SIB1 has failed. In UE100 according to this embodiment, receiver 112 receives from the first cell a SIB1 request setting related to settings for requesting on-demand SIB1 from a second cell that supports on-demand SIB1 broadcast in response to a request. Transmitter 111 transmits a request for on-demand SIB1 to the second cell based on the SIB1 request setting. Controller 120 determines the waiting period based on period information included in the SIB1 request setting and related to the waiting period until a positive response to the request is received. As a result, UE100 can determine that the request for SIB1 has failed if it does not receive a positive response until the determined waiting period has elapsed. As a result, UE100 can avoid continuing to attempt to receive SIB1, and can properly acquire SIB1. In addition, the network can control the waiting period of the UE 100 using the period information.

Furthermore, in cases where UE100 requests on-demand SIB1, a method for acquiring other SIBs different from on-demand SIB1 is not specified. This raises concerns that UE100 may not be able to properly acquire other SIBs. In UE100 according to this embodiment, receiver 112 receives from the first cell a SIB1 request setting related to a setting for requesting on-demand SIB1 from a second cell that supports on-demand SIB1 broadcast in response to a request. Based on the SIB1 request setting, controller 120 controls the acquisition of other system information blocks (SIBs) of the second cell different from on-demand SIB1. As a result, UE100 performs an operation for acquiring other SIBs based on the SIB1 request setting, enabling the network to control the acquisition of other SIBs and making it possible to properly acquire other SIBs of the second cell.

(Base station configuration)
The configuration of the base station 200 according to the 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.

The communication unit 210, for example, receives radio signals from the UE 100 and transmits radio signals 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 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.

The network communication unit 220 transmits and receives signals to 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 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 signals to the core network device 300.

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

Base station 200 configured in this manner is a base station that manages a first cell. In base station 200, transmitter 211 transmits from the first cell to UE 100 an SIB1 request configuration related to a configuration for requesting on-demand SIB1 from multiple 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 requests corresponding to each of the multiple second cells. As a result, UE 100 can receive SIB1 from the target second cell by transmitting a request for SIB1 using uplink resource information included in the SIB1 request configuration corresponding to the target second cell, making it possible to properly acquire SIB1.

Furthermore, the transmitting unit 211 transmits from the first cell to the UE 100 an SIB1 request setting regarding the setting to be requested of a second cell that supports system information block type 1 (on-demand SIB1) that is broadcast upon request. The SIB1 request setting includes period information regarding the waiting period until an acknowledgment to the request is received. As a result, if the UE 100 does not receive an acknowledgment until the determined waiting period has elapsed, it 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 properly acquire SIB1. Furthermore, the network can control the waiting period of the UE 100 using the period information.

In addition, the transmitter 211 transmits, from the first cell to the UE 100, an SIB1 request setting related to the setting to be requested of the second cell that supports system information block type 1 (on-demand SIB1) broadcast upon request. The SIB1 request setting 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 setting, allowing the network to control the acquisition of other SIBs and enabling the other SIBs of the second cell to be appropriately acquired.

(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.

In FIG. 5, UE100 may be in an RRC idle state or an RRC inactive state with cell C1 managed by base station 200. Alternatively, UE100 may be in an RRC connected state with cell C1. That is, the RRC state of UE100 may be an RRC idle state, an RRC inactive state, or an RRC connected state. Cell C1 may be a cell on which UE100 is camped, or may be a cell that UE100 has (re)selected. Cell C1 may be a cell with which UE100 has established an RRC connection. That is, cell C1 may be a serving cell.

Cells C1, C2, and C3 may be managed by the same base station 200. Cells C1, C2, and C3 may be managed by different base stations 200. For example, one base station 200 may manage cells C1 and 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 a base station 200 manages cells C1 and C2, and another base station 200 manages cell C3.

In this operation example, a cell that periodically broadcasts (i.e., transmits) System Information Block Type 1 (SIB1) is referred to as the first cell. The first cell may be a cell that does not support on-demand SIB1 (i.e., on-demand SIB1 functionality). The first cell may be a cell that broadcasts SIB1 without a request from UE100. The first cell may also 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., P-cell) for UE100.

In this operation example, a cell that does not always periodically broadcast (i.e., transmit) system information block type 1 (SIB1) is referred to as the 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 functionality). The second cell may be a cell that starts broadcasting SIB1 based on a request from 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 on-demand SIB1 may be transmitted from the first cell (i.e., base station 200 managing the first cell) to UE 100. For example, information indicating support for on-demand SIB1 may be included in a SIB1 request configuration, which will be described later. UE 100 may perform operations related to an on-demand SIB1 request, which will be described later, based on the information indicating support for on-demand SIB1. In this operation example, cell C2 and cell C3 are second cells.

Note that in this specification, for UE100, communication with base station 200 may also be communication with a cell. For example, base station 200 may transmit information/messages, etc. to UE100 from a certain cell (or in a certain cell). For UE100, receiving information/messages, etc. from a cell may also be receiving information/messages, etc. from base station 200. Similarly, base station 200 may receive information/messages, etc. from UE100 via a certain cell (or in a certain cell). For the UE, transmitting information/messages, etc. to a cell may also be transmitting information/messages, etc. to base station 200.

Step S101:
The transmitter 211 of the base station 200 transmits the 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.

The SIB1 request configuration may be information (e.g., On-demand SIB1 request config.) regarding the 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 the SIB1 from cell C1 (i.e., the SIB1 message). The SIB1 request configuration may be included in a system information block associated with 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). UE100 may request cell C1 to broadcast SIBX. In response to a request from UE 100, base station 200 may transmit a SIBX including an SIB1 request configuration to UE 100.

When UE100 is in the RRC connected state, the transmitter 211 of base station 200 may transmit an individual RRC message including the SIB1 request setting from cell C1 to UE100. The receiver 112 of UE100 may receive the individual RRC message from cell C1. The controller 120 of UE100 may store the SIB1 request setting 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 UE100 is in the RRC connected state, it transitions to the RRC idle state or the RRC inactive state before step S103 described below.

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

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 for 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 set by the BWP information. Furthermore, the information indicating the subcarrier spacing may indicate the subcarrier spacing used for all channels and/or reference signals in the bandwidth portion set by the BWP information.

The ULBWP information may include initial uplink BWP information (e.g., initialUplinkBWP) indicating settings for the initial uplink BWP. The initial uplink BWP information may be information used only for requesting on-demand SIB1. Therefore, for example, an RRC message including a SIB1 request setting 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 on-demand SIB1 may also be used for initial access to the second cell. The initial uplink BWP information may be common to both settings for requesting on-demand SIB1 and settings for initial access. In this case, the RRC message including the SIB1 request setting does not need to include 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.

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 on-demand SIB1. Thus, for example, an RRC message including a SIB1 request setting 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 on-demand SIB1 may also be used for initial access to the second cell. The RACH resource information may be common to the settings for requesting an on-demand SIB1 and for initial access. In this case, the RRC message including the SIB1 request settings does not need to include RACH resource information for initial access to the second cell.

That is, the RACH resource information may include random access parameters used by UE100 to request on-demand SIB1. For example, the RACH resource information may include information for setting a random access opportunity for the request for on-demand SIB1. The random access opportunity may correspond to an opportunity for transmission of a physical random access channel (PRACH) (i.e., transmission of 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. The RACH resource information may also include information for setting an index of a random access preamble for the request for on-demand SIB1. For example, the random access preamble may be specified as 64 numbers having indices from 0 to 63, and the random access preamble for the request for 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, UE 100 may request broadcast (i.e., start of broadcast) of on-demand SIB1 from cell C2 by transmitting a random access preamble during a random access opportunity of the uplink BWP. The RACH resource information may also include information for setting a period (window) for receiving message 2 corresponding to the PRACH transmission. For example, the period for receiving message 2 may be defined as the length of a slot, and UE 100 may consider the random access procedure to be successfully completed if it receives message 2 during that period in response to the PRACH transmission. That is, as described below, UE 100 may consider the request for on-demand SIB1 to be successfully completed if it receives message 2 during that period.

The uplink resource information may include information (e.g., si-RequestConfig) indicating the configuration of resources for Message 1 used by UE 100 to request SIB1 or an SI message for SIB1. Furthermore, the uplink resource information may include information (e.g., SI-SchedulingInfo) including information necessary for requesting SIB1 or an SI message for SIB1. Furthermore, the information (e.g., si-RequestConfig) indicating the configuration of resources for Message 1 used by UE 100 may include uplink resource information and/or information (e.g., SI-SchedulingInfo) including information necessary for requesting SIB1 or an SI message for SIB1. For example, the information (e.g., si-RequestConfig) indicating the configuration of resources for Message 1 used by UE 100 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, if the SIB1 request configuration does not include uplink resource information, the UE 100 does not need to request an on-demand SIB1.

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.

The SIB1 request setting may include information regarding the transmission of on-demand SIB1 (hereinafter referred to as transmission information). The transmission information may include information indicating at least one of the number of times on-demand SIB1 is transmitted, the transmission period of on-demand SIB1, and the transmission duration of 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 changed. 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 the association (correspondence) between the SSBs and random access opportunities and/or information indicating the threshold used to select the SSBs. The transmission information may include, for example, information indicating the number of modification periods and/or the number of periods 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, 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.

Here, the modification period may be a period used for updating system information messages (e.g., updating the contents of SIB1). That is, system information messages with the same contents may be broadcast during 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 a paging cycle (e.g., a default paging cycle). Furthermore, the information indicating the cycle may be information corresponding to a paging cycle in cell C2 (e.g., a default paging cycle).

Furthermore, the modification period (e.g., the boundary of the modification period) may be specified by the value of the system frame number (SFN). Here, information indicating the SFN value may be included in the MIB transmitted on the PBCH included in the SSB. That is, UE100 may acquire the on-demand SIB1 from cell C2 based on the SIB1 request setting from cell C1 and/or the SSB from cell C2 (e.g., information indicating the SFN value included in the MIB). Furthermore, information indicating the SFN value may be included in the SIB1 request setting and transmitted from cell C1.

As described above, UE100 may request broadcast of on-demand SIB1 based on transmission of a random access preamble in a random access opportunity configured for a request for on-demand SIB1. Here, UE100 may transmit a request for on-demand SIB1 only in the current modification period. That is, since the random access opportunity and/or random access preamble configured for a request for on-demand SIB1 may change from the start of the next modification period, UE100 may transmit a request for SIB1 only in the current modification period. UE100 may also transmit a request for on-demand SIB1 from the start of the next modification period. That is, since the random access opportunity and/or random access preamble used in the current modification period may not correspond to the random access opportunity and/or random access preamble for a request for on-demand SIB1, UE100 may transmit a request for on-demand SIB1 from the start of the next modification period.

Here, base station 200 may notify UE 100 of an update to 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 to the system information message, it 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 the successful completion of the request for on-demand SIB1. UE 100 may receive notification of the update to the system information message (e.g., on-demand SIB1) based on the short message transmitted on the PDCCH with a CRC scrambled by the P-RNTI, and acquire the system information message (e.g., on-demand SIB1) from the start of the next modification period.

UE100 may also select a random access opportunity to be used for requesting on-demand SIB1 based on information about the SS burst set. For example, UE100 may determine a random access opportunity associated with an SSB based on information indicating the association (correspondence) between the SSB and the random access opportunity. UE100 may also measure the received power (e.g., reference signal power (RSRP)) based on the SSB, select an SSB with a received power higher than a threshold set by information indicating the threshold used for selecting the SSB, and select a random access opportunity associated with the selected SSB. UE100 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.

Furthermore, the SIB1 request setting may include information regarding the transmission of an 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 an on-demand SIB1 request, the transmission period of an on-demand SIB1 request, and the transmission duration of an on-demand SIB1 request. The transmission request information may include, for example, information indicating the number of modification periods and/or the period of an SS burst set (e.g., a multiple). The control unit 120 of the UE 100 may determine at least one of the number of transmissions of an on-demand SIB1 request, the transmission period of an on-demand SIB1 request, and the transmission duration of an on-demand SIB1 request based on the modification period and/or the period of an SS burst set.

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

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 UE 100 is identical to the newly received SIB1 request configuration. The validity information may include information indicating a timer value or period used to measure the validity of the SIB1 request configuration. Based on the validity information (e.g., based on receiving a validity information value that is not identical to the stored validity information value), the control unit 120 of UE 100 may start a timer or period set to the timer 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) that includes the validity information.

For example, UE100 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, UE100 may request an on-demand SIB1 from cell C2 based on a system information message (e.g., SIB1 request setting) set from cell C1. UE100 may store the system information message (e.g., SIB1 request setting) as a valid version of the system information message. UE100 may also determine whether the stored system information message is valid based on validity information included in the received system information message. For example, UE100 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 setting may include a cell identifier. Here, the validity information may be set corresponding to the cell identifier (i.e., may be set 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 configuration 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 configuration for cell C2) that is stored, UE 100 may consider the system information message for the certain cell that is stored (e.g., SIB1 request configuration for cell C2) to be valid.

The SIB1 request configuration (hereinafter sometimes referred to as the 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 the second SIB1 request configuration). The first SIB1 request configuration (specifically, "On-demand SIB1 request config." in Figure 5) may include multiple second SIB1 request configurations. Therefore, the SIB1 request configuration may be composed of multiple SIB1 request configurations (i.e., multiple second SIB1 request configurations) corresponding to multiple second cells. Therefore, the transmitter 211 of the base station 200 may transmit multiple SIB1 request configurations from cell C1 to UE100. The receiver 112 of the UE 100 may receive multiple SIB1 request configurations from the cell C1. The SIB1 request configuration may also be configured with SIB1 request configurations corresponding to multiple second cells. Therefore, the transmitter 211 of the base station 200 may transmit the SIB1 request configurations corresponding to multiple second cells from the cell C1 to the UE 100. The receiver 112 of the UE 100 may receive the SIB1 request configurations corresponding to multiple second cells from the cell C1.

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

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 neighboring cell information. The neighboring cell information may, for example, be a list in which each of the cell identifiers of multiple neighboring cells that are candidates for cell reselection is entered. The neighboring cell information may be an intra-frequency neighboring cell list (e.g., intraFreqNeighBellList), which is a list of intra-frequency neighboring cells accompanied by specific cell reselection parameters. The neighboring cell information may also be an inter-frequency neighboring cell list (e.g., interFreqNeighBellList), which is a list of inter-frequency neighboring cells accompanied by specific cell reselection parameters. The receiving unit 112 of the UE 100 may have received the list of neighboring cell information (i.e., the intra-frequency neighboring cell list and/or the inter-frequency neighboring cell list) from the first cell. For example, the intra-frequency neighboring 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.

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

The SIB1 request settings 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 UE100 holds the list of neighboring cell information, it can determine which SIB1 request settings correspond to which second cell based on the position of the SIB1 request settings entry in the list of SIB1 request settings. Therefore, each SIB1 request setting 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 setting field for a cell that is not the second cell may include, for example, dummy information that is ignored by UE100.

That is, UE100 may determine the second cell based on the intra-frequency neighboring cell list included in SIB3. For example, UE100 may transmit a request for on-demand SIB1 based on multiple SIB1 request settings included in SIB1 and the intra-frequency neighboring cell list included in SIB3. That is, UE100 may transmit a request for on-demand SIB1 to a cell (e.g., cell C2) determined based on the intra-frequency neighboring cell list included in SIB3 using the corresponding SIB1 request setting included in SIB1. UE100 may also determine the second cell based on the inter-frequency neighboring cell list included in SIB4. For example, UE100 may transmit a request for on-demand SIB1 based on multiple SIB1 request settings included in SIB1 and the inter-frequency neighboring 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 neighboring cell list included in SIB4 using the corresponding SIB1 request setting included in SIB1.

The SIB1 request configuration may be composed of only the SIB1 request configuration corresponding to the second cell from the list of neighboring cell information (i.e., the intra-frequency neighboring cell list and/or the inter-frequency neighboring cell list). In this case, each SIB1 request configuration may include the cell identifier of the second cell and uplink resource information of the second cell.

As described above, the SIB1 request setting may have a similar configuration to a list of neighboring cell information (i.e., an intra-frequency neighboring cell list and/or an inter-frequency neighboring cell list). Therefore, the SIB1 request setting may be divided into a list of intra-frequency second cells and a list of inter-frequency second cells, or the SIB1 request setting may be a single common list for both intra-frequency second cells and inter-frequency second cells.

In addition, the receiving unit 112 of UE 100 may receive a list of cell identifiers of second cells and a list of SIB1 request settings associated with each cell identifier. That is, one SIB1 request setting may include a list of cell identifiers associated with each of multiple second cells and a list of settings for on-demand SIB1 requests. That is, for example, each of the information included in the SIB1 request setting described above may be included as a list. For example, cell identifiers corresponding to each of multiple second cells may be set as a list, and multiple uplink resource information, multiple transmission information, multiple transmission request information, information indicating the transmission status of multiple on-demand SIB1s, multiple validity information, and/or multiple downlink resource information described below may be set correspondingly as a list. For example, UE 100 may determine the uplink resource information, transmission information, transmission request information, information indicating the transmission status of on-demand SIB1, and/or validity information corresponding to the cell identifier from the order of the cell identifiers included in the list and the order of the uplink resource information, transmission information, transmission request information, information indicating the transmission status of on-demand SIB1, and/or validity information included in the list. In this embodiment, it is described that multiple SIB1 request settings are configured, but the configuration of multiple SIB1 request settings also includes the corresponding settings and/or information being configured as a list.

In other words, when the control unit 230 of the base station 200 transmits SIB1 request settings including information about multiple second cells to the UE 100, the control unit 230 may notify the UE 100 of validity information corresponding to each of the SIB1 request settings. Here, the control unit 230 of the base station 200 may notify the UE 100 of one piece of validity information common to the multiple SIB1 request settings. In other words, one piece of validity information (validity information value) may be transmitted to the UE 100 for the multiple SIB1 request settings corresponding to the multiple cells included in the system information message.

Here, the RRC message (system information message and/or individual RRC message) may be a message exchanged at the RRC layer in UE100 and/or base station 200. Furthermore, the random access procedure may be exchanged at the MAC layer in UE100 and/or base station 200. That is, for example, the RRC layer in UE100 may notify the MAC layer of the SIB1 request setting, and the MAC layer in UE100 may perform (trigger) a random access procedure to request on-demand SIB1 based on the notification of the SIB1 request setting from the RRC layer. Furthermore, for example, the MAC layer in UE 100 may notify the RRC layer of information indicating that an acknowledgment message (described below) has been received (i.e., 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 (or start acquiring the on-demand SIB1) based on the notification of the reception of the acknowledgment message from the MAC layer. Furthermore, the PDCCH with a CRC scrambled by the System Information Radio Network Temporary Identifier (SI-RNTI) is monitored by the PHY layer in UE 100. That is, the MAC layer in UE 100 may notify the PHY layer of information indicating that the acknowledgment message has been received, and the PHY layer in UE 100 may start monitoring the PDCCH with a CRC scrambled by the SI-RNTI based on the notification of the reception of the acknowledgment message from the MAC layer.

Step S102:
The transmitter 211 of the base station 200 transmits SSB from cell C2. The transmitter 211 of another base station 200 transmits SSB from cell C3. The receiver 112 of the UE 100 receives 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.

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 the cell C2 is (re)selected. That is, the description will proceed assuming that the cell C2 is (re)selected as the serving cell.

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.

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.

When the SIB1 request setting includes information about multiple second cells (cells C2 and C3 in this embodiment), the control unit 120 of UE100 may transmit an on-demand SIB1 request to cell C2, which is the (re)selected cell, based on the SIB request setting corresponding to cell C2. That is, UE100 may transmit an on-demand SIB1 request to a (re)selected and/or camped-on cell (e.g., cell C2) based on the SIB1 request setting corresponding to the cell. The control unit 120 may transmit an on-demand SIB1 request to cell C2, for example, based on the SIB1 request setting associated with the cell identifier indicating cell C2 in the SIB1 request setting.

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

If the control unit 120 determines that an on-demand SIB1 request should be sent, it may execute this step. On the other hand, if the control unit 120 determines that an on-demand SIB1 request should not be sent, it may execute the operation of receiving SIB1 as usual without sending an on-demand SIB1 request.

Furthermore, if the SIB request configuration includes information indicating the transmission status of on-demand SIB1, the control unit 120 of UE100 may determine whether to transmit an on-demand SIB1 request based on the information indicating the transmission status of on-demand SIB1. If the information indicates that on-demand SIB1 is not being transmitted, the control unit 120 of UE100 may determine to transmit an on-demand SIB1 request. On the other hand, if the information indicates that on-demand SIB1 is being (temporarily) transmitted, the control unit 120 of UE100 may determine not to transmit an on-demand SIB1 request.

The control unit 120 may determine whether the SIB1 request setting corresponding to cell C2 is valid based on the validity information. For example, the control unit 120 may determine whether the value of the validity information corresponding to the SIB1 request setting is the same as the value of the validity information corresponding to the newly received SIB1 request setting. That is, even after performing cell (re)selection to cell C2, UE100 may continue to use the SIB1 request setting set from cell C1 and stored. Furthermore, UE100 may update the contents of the stored SIB1 request setting based on the value of the validity information indicating that the contents of the SIB1 request setting have been updated, rather than updating the contents every time it receives the SIB1 request setting that is included in a system information message and broadcast periodically.

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

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

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

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. The control unit 230 of the base station 200 may also 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 UE 100 of an update to 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 UE 100 of an update to the system information message.

The receiving unit 112 of UE100 may receive on-demand SIB1 from cell C2 based on the transmission information. The control unit 120 of UE100 may execute control to receive on-demand SIB1 based on the transmission information. The control unit 120 may, for example, determine at least one of the number of transmissions of on-demand SIB1, the transmission period of on-demand SIB1, and the transmission duration of on-demand SIB1 based on the transmission information. The control unit 120 may also determine at least one of the number of transmissions of on-demand SIB1, the transmission period of on-demand SIB1, and the transmission duration of 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 on-demand SIB1 at the timing when on-demand SIB1 is being transmitted based on at least one of the determined number of transmissions of on-demand SIB1, the transmission period of on-demand SIB1, and the transmission duration of on-demand SIB1. Furthermore, the control unit 120 of the UE 100 (e.g., the RRC layer of the UE 100) may immediately start acquiring the on-demand SIB1 based on notification of the reception of an 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.

Then, 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.

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

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

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 desired second cell.

Furthermore, the uplink resource information may include configuration information for setting the uplink bandwidth portion for transmitting the request. This allows UE 100 to appropriately request on-demand SIB 1 by transmitting a request for on-demand SIB 1 using the uplink bandwidth portion set by the configuration information.

Furthermore, the uplink resource information may include configuration information used to identify random access parameters for transmitting the request. This allows UE 100 to appropriately request on-demand SIB 1 by transmitting a request for on-demand SIB 1 using the random access parameters identified by the configuration information.

Furthermore, the SIB1 request configuration may include transmission information regarding the transmission of the on-demand SIB1 from each of the multiple 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.

The transmission information may also include information indicating at least one of the number of times on-demand SIB1 is transmitted, the transmission cycle of on-demand SIB1, and the transmission period of on-demand SIB1. By knowing at least one of the number of times on-demand SIB1 is transmitted, the transmission cycle of on-demand SIB1, and the transmission period of on-demand SIB1, the receiving unit 112 of UE100 can appropriately acquire on-demand SIB1.

Furthermore, the transmitter 211 of the base station 200 may transmit validity information used to determine the validity of the SIB1 request setting from the first cell to the UE 100. The receiver 112 of the UE 100 may receive the validity information used to determine the validity of the SIB1 request setting from the first cell. The controller 120 of the UE 100 may determine whether the SIB1 request setting corresponding to one second cell is valid based on the validity information. This allows the UE 100 to appropriately request an on-demand SIB1 by transmitting a request for the on-demand SIB1 based on the valid SIB1 request setting.

Furthermore, if the SIB1 request setting 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 setting from the first cell. This allows the UE 100 to appropriately request an on-demand SIB1 by transmitting a request for the on-demand SIB1 based on the new SIB1 request setting.

(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.

The following description will be given assuming that UE100 has already received the SIB1 request configuration from cell C1. The SIB1 request configuration may include downlink resource information.

The downlink resource information may include information indicating the downlink bandwidth portion (DLBWP) over which Message 2, described below, is transmitted. The downlink resource information may include information (e.g., PDCCH-ConfigCommon) indicating settings for receiving (monitoring) the PDCCH, described below. This information may be information used to set cell-specific PDCCH parameters. This information may be information for setting a common search space (CSS). This CSS may be, for example, a Type 1 PDCCH CSS for receiving Message 2. This 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 setting the value of the RA-RNTI. This CSS may also be a Type 2 PDCCH CSS for receiving short messages. That is, the CSS may be a Type 2 PDCCH CSS for a PDCCH with a CRC scrambled by the P-RNTI. The downlink resource information may also include information for setting the value of the P-RNTI.

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 corresponding to the cell C2 and/or a random access preamble configured corresponding to 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.

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.

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 a downlink assignment) indicating the radio resource allocation of message 2. That is, for example, PDSCH resources may be scheduled using a PDCCH with a CRC scrambled by the RA-RNTI. Here, message 2 may include a PDCCH with a CRC scrambled by the RA-RNTI and a PDSCH scheduled by the PDCCH. Message 2 may also be referred to as a random access response.

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

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.

Message 2 may be an acknowledgment message to message 1.

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

When receiving message 2, the control unit 120 of UE 100 may determine whether specific information is included. 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) sent in the on-demand SIB1 request.

The control unit 120 may determine that reception of Message 2 is successful if Message 2 contains 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 contain 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) contains a MAC sub-PDU containing 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) contains a MAC sub-PDU containing 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). Additionally, the control unit 120 (e.g., MAC layer) may notify the PHY layer that it has received a positive response message to the SIB1 request (message 1).

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.

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 message.

The control unit 120 of UE100 monitors the PDCCH with a CRC scrambled by the SI-RNTI. For example, the control unit 120 (e.g., the PHY layer) of UE100 may start monitoring the PDCCH with a CRC scrambled by the SI-RNTI based on notification of the reception of a message for a positive response to the SIB1 request (message 1) from the MAC layer. The control unit 120 may determine the control resource set #0 (CORESET #0) and search space #0 (SS #0) in which the downlink control information (DCI) dedicated to SIB1 exists based on the SSB (specifically, the MIB) of cell C2. That is, the control unit 120 may determine the CORESET #0 and/or search space #0 for the PDCCH with a 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.

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

Here, the control unit 120 of UE 100 may monitor the PDCCH with a CRC scrambled by the P-RNTI. For example, the control unit 120 (e.g., the PHY layer) of UE 100 may start monitoring the PDCCH with a 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 a CRC scrambled by the P-RNTI, it may receive a notification of an update to 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 an update to the system information message. For example, the control unit 120 may attempt to receive the SI message (SIB1) from the start of the next modification period after receiving the notification of an update to the system information message.

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).

(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.

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.

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

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.

Note that the receiver 112 of UE 100 may receive message 2 in the same manner as in steps S202 and S203.

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.

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 requests on-demand SIB1 and SIBX together.

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.

Message 4 may be an acknowledgment message to message 3.

Steps S305 and S306:
This corresponds to steps S205 and S206.

Note that if the receiver 112 of UE 100 has requested another SIB, it may receive an SI message including SIBX in addition to the SI message including on-demand SIB1. UE 100 may also receive an SI message including on-demand SIB1 and SIBX.

(Fourth operation example)
A fourth operation example will be described with reference to FIG. 9. The previously mentioned explanation may be omitted. The explanation about cell C3 is the same as that of the first operation example, and therefore the explanation will be omitted. In this operation example, a case where UE 100 fails to receive on-demand SIB1 will be described.

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.

The SIB1 request setting may include duration information regarding the waiting period until an acknowledgment to the request is received. Here, 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 including the on-demand SIB1.

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 of modification periods and/or the period of the SS burst set (e.g., multiples).

The SIB1 request setting may include retransmission information regarding retransmission of on-demand SIB1 requests. The retransmission information may include at least one of retransmission count information that sets the maximum number of retransmissions of on-demand SIB1 requests and retransmission power information that sets the transmission power when retransmitting on-demand SIB1 requests. The retransmission power information may be information for setting power ramping.

Steps S402 to S404:
This corresponds to steps S102 to S104.

Step S405:
The control unit 120 of the UE 100 determines the 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.

Step S406:
The transmitter 211 of the base station 200 broadcasts the on-demand SIB1 from the cell C2 in response to a 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.

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

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 assume) 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.

The control unit 120 of UE100 may determine that the request for on-demand SIB1 has failed, for example, if it is unable to receive (a) a PDCCH with a CRC scrambled by the SI-RNTI as an affirmative response before the elapse of the elapsed period. The control unit 120 of UE100 may determine that the request for on-demand SIB1 has failed if it is unable to receive (b) a PDSCH carrying on-demand SIB1 as an affirmative response before the elapse of the elapsed period. The control unit 120 of UE100 may determine that the request for on-demand SIB1 has failed if it is unable to receive (c) a PDCCH with a CRC scrambled by the RA-RNTI as an affirmative response, or (d) message 2, which is a response to message 1 for the on-demand SIB1 request, 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 message 4, which is a response to message 3 for requesting (e) on-demand SIB1, as an affirmative response 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 an SI message including (f) on-demand SIB1 as an affirmative response before the elapse of the elapsed period.

If the waiting period has elapsed, the control unit 120 may execute the process of step S408. For example, if the SIB1 request setting includes retransmission information, the control unit 120 may execute the process of step S408. If the SIB1 request setting does not include retransmission information, the control unit 120 may omit the process of step S408.

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.

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 cell C2 at the transmission power based on the retransmission power information.

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 resend the request for the on-demand SIB1. If the number of times the on-demand SIB1 request has been sent 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 processing of step S409.

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.

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.

Step S410:
This corresponds to step S105.

As described above, the transmitter 211 of the base station 200 may transmit an SIB1 request setting related to settings for requesting an on-demand SIB1 from a second cell that supports the on-demand SIB1 to the UE 100 from the first cell. The SIB1 request setting may include period information related to the waiting period until an acknowledgment to the request is received. The receiver 112 may receive an SIB1 request setting related to settings for requesting an on-demand SIB1 from a second cell that supports the on-demand SIB1 from the first cell. The transmitter 111 may transmit a request for the on-demand SIB1 to the second cell based on the SIB1 request setting. The controller 120 may determine the waiting period based on the period information included in the SIB1 request setting and related to the waiting period until an acknowledgment to 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, UE100 can avoid continuously attempting to receive on-demand SIB1, and can appropriately acquire on-demand SIB1. In addition, the network can control the waiting period of UE100 using the period information.

The period information may also indicate a waiting period until a PDCCH with 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, it can determine that the request for the on-demand SIB1 has been successful.

The period information may also indicate a waiting period until the physical downlink shared channel (PDSCH) carrying the on-demand SIB1 is received 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 is unable to receive the on-demand SIB1 within the waiting period.

The period information may also indicate a waiting period until a PDCCH with 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 end of the waiting period, it can determine that the request for the on-demand SIB1 has been successful.

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

In addition to the period information, the control unit 120 may determine the waiting period based on at least one of the modification period during which the content of the second cell's system information may be changed and the period of a synchronization signal (SS) burst set composed of synchronization signal blocks (SS blocks). This makes it possible for the control unit 120 to determine the waiting period based on the modification period, thereby preventing 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.

Furthermore, if the transmitter 111 does not receive the on-demand SIB1 before the waiting period has elapsed, the transmitter 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 fails.

The SIB1 request configuration may also include at least one of information for setting the maximum number of retransmissions of an on-demand SIB1 request and information for setting the transmission power when retransmitting an on-demand SIB1 request. This allows the network to control the retransmission of on-demand SIB1 requests.

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

(Fifth operation example)
A fifth operation example will be described with reference to FIG. 10 . The previous explanation may be omitted. The explanation about cell C3 is the same as that of the first operation example, and therefore the explanation will be omitted. In this operation example, a case where UE 100 requests SIBX from cell C2 will be described. Note that the control unit 120 of UE 100 may control the transmission unit 111 to perform the following operations.

Step S501:
The transmitter 211 of the base station 200 transmits the 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.

The SIB1 request configuration may include uplink resource information used to transmit the on-demand SIB1 request. This uplink resource information may be referred to as first uplink resource information.

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

Step S505:
The transmitter 211 of the base station 200 broadcasts the on-demand SIB1 from the cell C2 in response to a request from the UE 100. The receiver 112 of the UE 100 receives the on-demand SIB1 from the cell C2.

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

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.

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.

Step S507:
The transmitter 211 of the base station 200 broadcasts the SIBX from the cell C2 in response to a request from the UE 100. The receiver 112 of the UE 100 receives the SIBX from the cell C2.

As described above, the transmitter 211 may transmit an SIB1 request setting related to settings for requesting the second cell that supports on-demand SIB1 from the first cell to the UE 100. The SIB1 request setting 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 setting related to settings 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 setting. As a result, the UE 100 performs an operation to acquire other SIBs based on the SIB1 request setting, allowing the network 10 to control the acquisition of other SIBs and making it possible to appropriately acquire other SIBs of the second cell.

Furthermore, the SIB1 request configuration may include first uplink resource information used to transmit the request for on-demand SIB1. The control unit 120 may perform control to transmit the request for 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 perform 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 the existing system.

(Sixth operation example)
A sixth operation example will be described with reference to FIG. 11 . Previous descriptions may be omitted. In this operation example, as in 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 whether it receives an on-demand SIB1. The control unit 120 of the UE 100 may control the transmission unit 111 to perform the following operations.

Step S601:
The transmitter 211 of the base station 200 transmits the 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.

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 from SIB2 onwards that constitute the other SIBs.

Steps S602 to S604:
This corresponds to steps S102 to S104. Note that the transmitter 111 of the UE 100 transmits the request for the on-demand SIB1 to the cell C2 by using the radio resource based on the first uplink resource information.

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.

The control unit 120 controls the transmission of a SIBX request to the second cell using radio resources based on the second uplink resource information. The control unit may control the transmission of a specific SIBX request to the second cell using radio resources based on radio resource information corresponding to a specific SIBX requested by UE100 from among multiple SIBXs. The control unit 120 may control the transmission of the SIBX request without waiting for reception of the on-demand SIB1. Therefore, UE100 may transmit the on-demand SIB1 request and the SIBX request in parallel.

Note that steps S604 and S605 may request on-demand SIB1 and/or SIBX, as in the second operation example.

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

Step S607:
This corresponds to step S507.

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 perform control to transmit the request for the other SIB to the second cell using radio resources based on the second uplink resource information. This enables the UE 100 to request the other SIB separately from the on-demand SIB1.

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 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 multiple SIBs. This enables the UE 100 to individually request other SIBs apart from the on-demand SIB 1.

(Seventh operation example)
A seventh operation example will be described with reference to FIG. 12 . Previous descriptions may be omitted. In this operation example, as in 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. The control unit 120 of the UE 100 may control the transmission unit 111 to perform the following operations.

Step S701:
The transmitter 211 of the base station 200 transmits the 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.

The SIB1 request configuration may include uplink resource information used in 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 to request on-demand SIB1 or an SI message for on-demand SIB1.

Steps S702 to S703:
This corresponds to steps S102 and S103.

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.

Note that step S704 may request on-demand SIB1 and SIBX, as in the third operation example.

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.

As described above, the control unit 120 of the UE 100 may perform control based on the SIB1 request setting to request the on-demand SIB1 and other SIBs together from the first cell or the second cell. This allows the UE 100 to request multiple SIBs together in a single message, thereby reducing the amount of signaling between the UE 100 and the base station 200.

Furthermore, 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 control unit 120 may control the transmission of one message requesting the on-demand SIB1 and other SIBs to the second cell. This makes it possible to request multiple SIBs collectively in one message in the random access procedure, and, for example, makes it possible to acquire multiple SIBs without transitioning to the RRC connected state.

(Eighth operation example)
An eighth operation example will be described with reference to FIG. 13 . 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 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.

Step S801:
The transmitter 211 of the base station 200 transmits the 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.

The SIB1 request configuration may include first uplink resource information used to send a request for on-demand SIB1 from cell C2 to cell C1, which is the first cell.

Steps S802 to S803:
This corresponds to steps S602 and S603.

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.

Step S805:
The transmitter 211 of the base station 200 broadcasts the on-demand SIB1 from the cell C1 in response to a request from the UE 100. The receiver 112 of the UE 100 receives the on-demand SIB1 from the cell C1.

The on-demand SIB1 is the SIB1 of cell C2. The on-demand SIB1 includes information about the settings for requesting the SIBX of cell C2 (hereinafter referred to as the SIBX request settings). The SIBX request settings may include second uplink resource information used to transmit the SIBX request.

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.

After receiving the 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.

Step S807:
The transmitter 211 of the base station 200 broadcasts the SIBX from the cell C1 in response to a request from the UE 100. The receiver 112 of the UE 100 receives the SIBX from the cell C1.

Then, the control unit 230 of UE100 may perform initial access to cell C2, for example, based on the on-demand SIB1 and SIBX received from cell C1.

As described above, the receiver 212 of the base station 200 may receive from the UE 100 a request for the on-demand SIB1 transmitted using radio resources based on the first uplink resource information. The transmitter 211 may transmit to the UE 100, based on the request for the on-demand SIB1, an on-demand SIB1 including second uplink resource information indicating radio resources to be used for the request for the other SIB. The transmitter 211 may transmit to the UE 100, based on the request for the other SIB transmitted using radio resources based on the second uplink resource information. The controller 120 of the UE 100 may control the transmission of the request for the on-demand SIB1 to the first cell using 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, allowing the network 10 to control the acquisition of the other SIB and making it possible to appropriately acquire the other SIB of the second cell.

(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 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.

Step S901:
The transmitter 211 of the base station 200 transmits the 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.

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, and second uplink resource information used to transmit a request for 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.

Steps S902 to S903:
This corresponds to steps S102 and S103.

Step S904:
This corresponds to step S804.

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.

The control unit 120 controls the transmission of a SIBX request to cell C1 using radio resources based on the second uplink resource information. The control unit may control the transmission of a specific SIBX request to cell C1 using radio resources based on radio resource information corresponding to a specific SIBX requested by UE100 from among multiple SIBXs. The control unit 120 may control the transmission of a SIBX request without waiting for reception of on-demand SIB1. Therefore, UE100 may transmit a request for on-demand SIB1 and a SIBX request in parallel.

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

Step S907:
This corresponds to step S507.

Then, the control unit 230 of UE100 may perform initial access to cell C2, for example, based on the on-demand SIB1 and SIBX received from cell C1.

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 receiver 212 of the base station 200 may receive the request for the other SIB from the UE 100 using radio resources based on the second uplink resource information. The controller 120 of the UE 100 may control the transmission of the request for the other SIB to the second cell using radio resources based on the second uplink resource information. This enables the UE 100 to request the other SIB separately from the on-demand SIB1.

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 receiver 212 of the base station 200 may receive a request for a specific SIB from the UE 100 using radio resources based on radio resource information corresponding to a specific SIB requested by the UE 100 out of the multiple SIBs. This allows the UE 100 to individually request other SIBs apart from the on-demand SIB1.

(Tenth operation example)
A tenth operation example will be described with reference to FIG. 15 . Previous descriptions may be omitted. In this operation example, as in the fifth operation example, a case will be described in which the UE 100 requests SIBX from the cell C1. As in 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.

Step S1001:
The transmitter 211 of the base station 200 transmits the 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.

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

Steps S1002 to S1003:
This corresponds to steps S102 and S103.

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. 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, for example. The one message may be message 3 in the random access procedure.

Note that step S1004 may request on-demand SIB1 and SIBX, as in the third operation example.

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.

Then, the control unit 230 of UE100 may perform initial access to cell C2, for example, based on the on-demand SIB1 and SIBX received from cell C1.

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

(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.

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.

If the SIB1 request setting includes specific resource information, the control unit 120 may execute the process of step S1102. On the other hand, if the SIB1 request setting does not include specific resource information, the control unit 120 may execute the process of step S1103. Based on the SIB1 request setting, the control unit 120 may determine the transmission method for transmitting requests for other SIBs to cell C1 or cell C2 as follows:

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

Step S1103:
The control unit 120 determines, as a transmission method, a method of 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.

As described above, the control unit 120 of the UE 100 may determine the 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 multiple transmission methods.

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

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

(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.

In the above-described embodiment, the SIB1 request setting may be, for example, a specification that predefines multiple settings (e.g., a second SIB1 request setting) for requesting an on-demand SIB1. The base station 200 may transmit to the UE 100 a SIB1 request setting (a first SIB1 request setting) that includes information specifying one of the multiple settings. The UE 100 may apply the specified SIB1 request setting based on the specifying information.

In the above-described embodiment, an NR-based mobile communication system was used 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 of the 3GPP standard (e.g., the 6th generation). 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).

A program may be provided that causes a computer to execute each process performed by UE100 or 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, but may be, for example, 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 UE100 or base station 200 may be integrated, and at least a portion of UE100 or base station 200 may be configured as a semiconductor integrated circuit (chipset, SoC (System On Chip)).

In the above 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 other nodes, or obtaining information by generating 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 does mean 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.

Although the present disclosure has been described with reference to examples, it is understood that the present disclosure is not limited to those examples or structures. The present disclosure also encompasses various modifications and modifications within the scope of equivalents. In addition, various combinations and forms, as well as other combinations and forms including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

(Additional Note)
The following additional notes are about the features of the above-described embodiment.

(Appendix 1)
a receiving unit (112) for receiving system information from a serving cell, the system information including information regarding a setting for requesting an on-demand SIB1;
a control unit (120),
The information regarding the configuration for requesting the on-demand SIB1 includes information indicating time and frequency resources of a physical random access channel (PRACH) and information indicating a window of a random access response defined by a slot length;
When the control unit transmits the request for the on-demand SIB1 using a PRACH resource indicated based on information indicating the time and frequency resources of the PRACH, the control unit controls the communication device to monitor the random access response corresponding to the request for the on-demand SIB1 during a period indicated based on information indicating a window for the random access response.
(Appendix 2)
The information on the configuration for requesting the on-demand SIB1 includes one or more physical cell identifiers, information indicating time and frequency resources of the PRACH corresponding to each of the one or more physical cell identifiers, and information indicating a window of the random access response corresponding to each of the one or more physical cell identifiers;
a transmitter (111) for transmitting a request for the on-demand SIB1 to a cell identified by one or more physical cell identifiers using a PRACH resource indicated based on information indicating the time and frequency resource of the PRACH;
The communication device according to Supplementary Note 1, wherein the control unit controls to monitor the random access response in a cell having a physical cell identifier corresponding to transmission of the on-demand SIB1 request.
(Appendix 3)
3. The communications device of claim 1, wherein the random access response indicates a positive response corresponding to transmission of the request for the on-demand SIB1.
(Appendix 4)
a receiving unit (212) that receives, from a communication device that has received system information including information regarding a setting for requesting an on-demand SIB1, a request for the on-demand SIB1 transmitted using a physical random access channel (PRACH) resource indicated based on information indicating time and frequency resources of the PRACH included in the information regarding the setting for requesting the on-demand SIB1;
a transmitting unit (211) configured to transmit the random access response corresponding to the request for the on-demand SIB1 during a period indicated based on information indicating a window of the random access response, the window being defined by a slot length included in information regarding settings for requesting the on-demand SIB1.
(Appendix 5)
The information on the configuration for requesting the on-demand SIB1 includes one or more physical cell identifiers, information indicating time and frequency resources of the PRACH corresponding to each of the one or more physical cell identifiers, and information indicating a window of the random access response corresponding to each of the one or more physical cell identifiers;
The receiving unit receives, from the communication device, a request for the on-demand SIB1 transmitted using a PRACH resource indicated based on information indicating a time and frequency resource of the PRACH in a cell identified by any of the one or more physical cell identifiers;
The base station according to Supplementary Note 4, wherein the transmitter transmits the random access response in a cell having a physical cell identifier corresponding to transmission of the on-demand SIB1 request.
(Appendix 6)
6. The base station according to claim 4, wherein the random access response indicates an acknowledgement corresponding to transmission of the request for the on-demand SIB1.
(Appendix 7)
1. A communication method performed in a communication device, comprising:
receiving system information from a serving cell, the system information including information regarding a configuration for requesting an on-demand SIB1;
The information regarding the configuration for requesting the on-demand SIB1 includes information indicating time and frequency resources of a physical random access channel (PRACH) and information indicating a window of a random access response defined by a slot length;
When the request for the on-demand SIB1 is transmitted using a PRACH resource indicated based on information indicating a time and frequency resource of the PRACH, controlling to monitor the random access response corresponding to the request for the on-demand SIB1 during a period indicated based on information indicating a window of the random access response.
Communication method.
(Appendix 8)
1. A communication method performed in a base station, comprising:
receiving, from a communication device that has received system information including information about a setting for requesting an on-demand SIB1, a request for the on-demand SIB1 transmitted using a Physical Random Access Channel (PRACH) resource indicated based on information indicating time and frequency resources of the PRACH included in the information about the setting for requesting the on-demand SIB1;
and transmitting the random access response corresponding to the request for the on-demand SIB1 during a period indicated based on information indicating a window for the random access response, the window being defined by a slot length included in information regarding settings for requesting the on-demand SIB1.
(Appendix 9)
a receiving unit for receiving, from a first cell, a SIB1 request configuration for requesting an on-demand system information block type 1 (on-demand SIB1) from a second cell that supports the on-demand SIB1;
a transmitter configured to transmit a request for the on-demand SIB1 to the second cell based on the SIB1 request configuration;
A control unit that determines the waiting period based on period information included in the SIB1 request configuration and related to a waiting period until an acknowledgment for the request is received.

(Appendix 10)
The period information indicates a waiting period until a physical downlink control channel (PDCCH) with a cyclic redundancy check (CRC) scrambled by a system information radio network temporary identifier (SI-RNTI) is received from the second cell as the acknowledgment; and
The communication device according to Supplementary Note 9, wherein the receiving unit receives the on-demand SIB1 from the second cell based on scheduling information carried by the PDCCH.

(Appendix 11)
The communication device according to Supplementary Note 9 or 10, wherein the period information indicates a waiting period until a Physical Downlink Shared Channel (PDSCH) carrying the on-demand SIB1 is received from the second cell as the acknowledgment.

(Appendix 12)
The period information indicates a waiting period until a physical downlink control channel (PDCCH) with a cyclic redundancy check (CRC) scrambled by a random access radio network temporary identifier (RA-RNTI) is received from the second cell as the acknowledgment; and
12. The communication device according to any one of Supplementary Notes 9 to 11, wherein the receiving unit receives the on-demand SIB1 from the second cell based on scheduling information carried by the PDCCH.

(Appendix 13)
The transmitter transmits a request for the on-demand SIB1 to the second cell by a message 1 in a random access procedure;
13. The communication device according to any one of Supplementary Notes 9 to 12, wherein the period information indicates a waiting period until a message 2 that is a response to the message 1 is received from the second cell as the acknowledgment.

(Appendix 14)
The control unit determines 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 composed of synchronization signal blocks (SS blocks), in addition to the period information. The communication device described in any one of Supplementary Notes 9 to 13.

(Appendix 15)
The communication device according to any one of Supplementary Notes 9 to 14, wherein the transmission unit retransmits the request for the on-demand SIB1 if the on-demand SIB1 is not received before the waiting period has elapsed.

(Appendix 16)
The communication device according to claim 15, wherein the SIB1 request configuration includes at least one of information for setting a maximum number of retransmissions of the on-demand SIB1 request and information for setting a transmission power when the on-demand SIB1 request is retransmitted.

(Appendix 17)
The communication device according to any one of Supplementary Notes 9 to 16, wherein the control unit, when not receiving the on-demand SIB1 until the waiting period has elapsed, executes control to acquire a new SIB1 request configuration from the first cell.

(Appendix 18)
A base station that manages a first cell,
a transmitter configured to transmit, from the first cell to a communication device, a SIB1 request configuration for requesting a second cell that supports system information block type 1 (on-demand SIB1) broadcast on demand;
The SIB1 request configuration includes duration information regarding a waiting period until an acknowledgment for the request is received.

(Appendix 19)
The base station according to Supplementary Note 18, wherein the period information indicates a waiting period until a Physical Downlink Control Channel (PDCCH) with a Cyclic Redundancy Check (CRC) scrambled by a System Information-Radio Network Temporary Identifier (SI-RNTI) is received from the second cell as the acknowledgment.

(Appendix 20)
20. The base station according to claim 18 or 19, wherein the period information indicates a waiting period until a Physical Downlink Shared Channel (PDSCH) carrying the on-demand SIB1 is received from the second cell as the acknowledgment.

(Appendix 21)
21. The base station according to any one of Supplementary Notes 18 to 20, wherein the period information indicates a waiting period until a Physical Downlink Control Channel (PDCCH) with a Cyclic Redundancy Check (CRC) scrambled by a Random Access Radio Network Temporary Identifier (RA-RNTI) is received from the second cell as the acknowledgment.

(Appendix 22)
22. The base station according to any one of Supplementary Notes 18 to 21, wherein the period information indicates a waiting period until a message 2 that is a response to a message 1 in a random access procedure is received from the second cell as the acknowledgment.

(Appendix 23)
1. A communication method performed in a communication device, comprising:
receiving a SIB1 request configuration from a first cell regarding a configuration for requesting an on-demand system information block type 1 (on-demand SIB1) from a second cell that supports the on-demand SIB1;
sending a request for the on-demand SIB1 to the second cell based on the SIB1 request configuration;
determining the waiting period based on period information included in the SIB1 request configuration regarding a waiting period until an acknowledgment for the request is received.

Claims (8)

a receiving unit (112) for receiving system information from a serving cell, the system information including information regarding a setting for requesting an on-demand SIB1;
a control unit (120),
The information regarding the configuration for requesting the on-demand SIB1 includes information indicating time and frequency resources of a physical random access channel (PRACH) and information indicating a window of a random access response defined by a slot length;
When the control unit transmits the request for the on-demand SIB1 using a PRACH resource indicated based on information indicating the time and frequency resources of the PRACH, the control unit controls the communication device to monitor the random access response corresponding to the request for the on-demand SIB1 during a period indicated based on information indicating a window for the random access response. The information on the configuration for requesting the on-demand SIB1 includes one or more physical cell identifiers, information indicating time and frequency resources of the PRACH corresponding to each of the one or more physical cell identifiers, and information indicating a window of the random access response corresponding to each of the one or more physical cell identifiers;
a transmitter (111) for transmitting a request for the on-demand SIB1 to a cell identified by one or more physical cell identifiers using a PRACH resource indicated based on information indicating the time and frequency resource of the PRACH;
The communication device according to claim 1 , wherein the control unit controls to monitor the random access response in a cell having a physical cell identifier corresponding to the transmission of the on-demand SIB1 request. The communication device according to claim 1 or 2, wherein the random access response indicates an acknowledgement corresponding to the transmission of the request for the on-demand SIB1. a receiving unit (212) that receives, from a communication device that has received system information including information regarding a setting for requesting an on-demand SIB1, a request for the on-demand SIB1 transmitted using a physical random access channel (PRACH) resource indicated based on information indicating time and frequency resources of the PRACH included in the information regarding the setting for requesting the on-demand SIB1;
a transmitting unit (211) configured to transmit the random access response corresponding to the request for the on-demand SIB1 during a period indicated based on information indicating a window of the random access response, the window being defined by a slot length included in information regarding settings for requesting the on-demand SIB1. The information on the configuration for requesting the on-demand SIB1 includes one or more physical cell identifiers, information indicating time and frequency resources of the PRACH corresponding to each of the one or more physical cell identifiers, and information indicating a window of the random access response corresponding to each of the one or more physical cell identifiers;
The receiving unit receives, from the communication device, a request for the on-demand SIB1 transmitted using a PRACH resource indicated based on information indicating a time and frequency resource of the PRACH in a cell identified by any of the one or more physical cell identifiers;
The base station according to claim 4 , wherein the transmitter transmits the random access response in a cell having a physical cell identifier corresponding to the transmission of the on-demand SIB1 request. The base station according to claim 4 or 5, wherein the random access response indicates an acknowledgement corresponding to the transmission of the request for the on-demand SIB1. 1. A communication method performed in a communication device, comprising:
receiving system information from a serving cell, the system information including information regarding a configuration for requesting an on-demand SIB1;
The information regarding the configuration for requesting the on-demand SIB1 includes information indicating time and frequency resources of a physical random access channel (PRACH) and information indicating a window of a random access response defined by a slot length;
When the request for the on-demand SIB1 is transmitted using a PRACH resource indicated based on information indicating a time and frequency resource of the PRACH, controlling to monitor the random access response corresponding to the request for the on-demand SIB1 during a period indicated based on information indicating a window of the random access response.
Communication method. 1. A communication method performed in a base station, comprising:
receiving, from a communication device that has received system information including information about a setting for requesting an on-demand SIB1, a request for the on-demand SIB1 transmitted using a Physical Random Access Channel (PRACH) resource indicated based on information indicating time and frequency resources of the PRACH included in the information about the setting for requesting the on-demand SIB1;
and transmitting the random access response corresponding to the request for the on-demand SIB1 during a period indicated based on information indicating a window for the random access response, the window being defined by a slot length included in information regarding settings for requesting the on-demand SIB1.