Communication device, base station, and communication method

Abstract

A communication device (100) according to an embodiment of the present invention is provided with: a reception unit (112) that receives, from a base station (200), updated system information indicating a change in the period of a physical random access channel (PRACH) timing, and control information indicating a change in the period of the physical random access channel (PRACH) timing; the control information is information indicating a change in the period of the PRACH timing and is carried by signaling of a lower layer lower than a radio resource control (RRC) layer; and a control unit (120) that prioritizes either the updated system information or the control information in accordance with priority information received from the base station or a predetermined rule, and changes the period of the PRACH on the basis of the prioritized information.

Description

Cross Reference to Related Applications

[0001] This application is based on and claims priority to patent application No. 2023-174676, filed on October 6, 2023, the entire contents of which are incorporated herein by reference. Technical Field

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

[0003] In 3GPP (Third Generation Partnership Project), a standardization project for mobile communication systems, Network Energy Saving (NES) is being discussed. As one NES, a scheme for dynamically changing the period of the Physical Random Access Channel (PRACH) timing (hereinafter referred to as PRACH period) has been proposed (see, for example, Non-Patent Literature 1).

[0004] In the dynamic adaptation of PRACH timing, for example by changing the PRACH period based on downlink control information (DCI), the PRACH period can be changed at shorter time intervals compared to, for example, changing the PRACH period by updating system information blocks. As a result, network energy can be saved. Existing technical documents Non-patent literature

[0005] Non-patent literature 1: "RWS-230156" (On NW Energy Savings for Rel-19) Summary of the Invention

[0006] The communication equipment involved in the first aspect includes: a receiving unit that receives updated system information and control information from a base station, wherein the updated system information indicates a change in the period of the Physical Random Access Channel (PRACH) timing, and the control information is information indicating the change in the period of the PRACH timing and is carried by signaling at a lower layer below the Radio Resource Control (RRC) layer; and a control unit that, according to priority information received from the base station or a pre-defined rule, prioritizes one of the aforementioned updated system information and the aforementioned control information, and changes the period of the aforementioned PRACH based on the aforementioned priority information.

[0007] The second aspect involves a base station that sends updated system information and control information to a communication device. The updated system information changes the timing period of the Physical Random Access Channel (PRACH), and the control information changes the timing period of the PRACH and is carried by signaling at a lower layer than the Radio Resource Control (RRC) layer. The transmitting unit sends priority information to the communication device, which is used by the communication device to determine which information, the updated system information or the control information, takes precedence.

[0008] The third aspect relates to a communication method performed by a communication device. The aforementioned communication method includes: the steps of receiving updated system information and control information from a base station, wherein the updated system information indicates a change in the period of the Physical Random Access Channel (PRACH) timing, and the aforementioned control information is information indicating the change in the period of the aforementioned PRACH timing and is carried by signaling at a lower layer below the Radio Resource Control (RRC) layer; and the steps of prioritizing one of the aforementioned updated system information and the aforementioned control information according to priority information received from the aforementioned base station or a predefined rule, and changing the period of the aforementioned PRACH based on the aforementioned priority information. Attached Figure Description

[0009] The purpose, features, and advantages of this disclosure will become clearer from the following detailed description, taken in conjunction with the accompanying drawings. Figure 1 This is a diagram illustrating the configuration of a mobile communication system according to an embodiment. Figure 2 This is a diagram illustrating a configuration example of the protocol stack involved in the implementation. Figure 3 This is a diagram illustrating the configuration of the UE involved in the implementation method. Figure 4 This is a diagram illustrating the configuration of a base station according to an implementation method. Figure 5 This is a sequence diagram used to illustrate the first example of an action involved in the implementation method. Figure 6 This is a flowchart used to illustrate the first example of an action involved in the implementation method. Figure 7 This is a diagram (one of) used to illustrate the first example of an action involved in the implementation method. Figure 8 This is a diagram (second one) used to illustrate the first example of an action involved in the implementation method. Figure 9 This is a diagram (third one) used to illustrate the first example of the action involved in the implementation method. Figure 10 This is a sequence diagram used to illustrate a second example of an implementation method. Figure 11 This is a diagram used to illustrate a second example of an action involved in the implementation method. Detailed Implementation

[0010] The mobile communication system according to the embodiments will be described with reference to the accompanying drawings. In the drawings, the same or similar parts are labeled with the same or similar reference numerals.

[0011] However, the specific actions related to the dynamic adaptation of PRACH timing are not specified. Therefore, there are concerns that communication devices may be unable to properly perform the dynamic adaptation of PRACH timing.

[0012] Therefore, one of the objectives of this disclosure is to provide a communication device, base station, and communication method that can dynamically adapt to the timing of PRACH appropriately.

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

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

[0015] UE 100 is a communication device that communicates via base station 200. UE 100 can be a device used by a user. UE 100 can be, for example, a mobile phone terminal such as a smartphone, a tablet computer terminal, a laptop PC (personal computer), a communication module, or a communication card, or other portable device. UE 100 can be a vehicle (e.g., a car, tram, etc.) or a device installed therein (e.g., Vehicle UE: Vehicle User Equipment). UE 100 can be a transport vehicle other than a vehicle (e.g., a ship, airplane, etc.) or a device installed therein (e.g., Aerial UE: Airborne User Equipment). UE 100 can be a sensor or a device installed therein. Furthermore, UE 100 can also be referred to as a 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, or other names. Additionally, UE 100 is an example of a terminal, which may include factory equipment, etc.

[0016] NG-RAN 20 includes multiple base stations 200. Each base station 200 manages at least one cell. One or more base stations 200 may correspond to one or more cells. A base station 200 can be replaced by a cell, and a cell can be replaced by a base station 200. A cell constitutes the smallest unit of a communication area. A cell belongs to a frequency (carrier frequency). The term "cell" sometimes refers to a wireless communication resource and sometimes to a communication target of UE 100. Each base station 200 is capable of wireless communication with UE 100 located in its cell. Base stations 200 communicate with UE 100 using the RAN's protocol stack. Details about the protocol stack are described later. In addition, base stations 200 are connected to other base stations 200 (also referred to as neighboring base stations) via the Xn interface. Base stations 200 communicate with neighboring base stations via the Xn interface. In addition, base stations 200 provide NR user plane and control plane protocol termination for UE 100, connected to 5GC 30 via the NG interface. Such an NR base station 200 is sometimes referred to as a gNodeB (gNB).

[0017] 5GC 30 includes a core network device 300. The core network device 300 includes, for example, an AMF (Access and Mobility Management Function) and / or a UPF (User Plane Function). The AMF performs mobility management for the UE 100. The UPF provides functions dedicated to user plane (U-plane) processing. Both the AMF and UPF are connected to the base station 200 via an NG interface.

[0018] (Protocol stack configuration example) Next, refer to Figure 2 The following describes a configuration example of the protocol stack involved in this implementation.

[0019] The protocol for the radio segment between UE 100 and base station 200 includes the physical (PHY) layer, MAC (Medium Access Control) layer, RLC (Radio Link Control) layer, PDCP (Packet Data Convergence Protocol) layer, and RRC (Radio Resource Control) layer.

[0020] 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 UE100 and the PHY layer of base station 200 via physical channels.

[0021] The MAC layer performs data priority control, retransmission processing using Hybrid ARQ (HARQ), and random access procedures. Data and control information are transmitted between the MAC layer of UE 100 and the MAC layer of base station 200 via a transport channel. The MAC layer of base station 200 includes a scheduler. The scheduler determines the uplink and downlink transmission formats (transmission block size, modulation and coding scheme (MCS)) and allocates resources to UE 100.

[0022] The RLC layer utilizes 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 a logical channel.

[0023] The PDCP layer performs header compression / expansion and encoding / decoding.

[0024] The SDAP (Service Data Adaptation Protocol) layer can be configured as a higher layer than the PDCP layer. The SDAP layer maps IP flows to radio bearers: IP flows are the unit for QoS (Quality of Service) control in the core network, while radio bearers are the unit for QoS control in the AS (Access Stratum).

[0025] The RRC layer responds to the establishment, re-establishment, and release of radio bearers to control logical channels, transport channels, and physical channels. RRC signaling for various configurations is transmitted between the RRC layer of UE 100 and the RRC layer of base station 200. When an RRC connection exists between the RRC layers of UE 100 and base station 200, UE 100 is in an RRC connected state. When there is no RRC connection between UE 100 and base station 200, UE 100 is in an RRC idle state. When the RRC connection between UE 100 and base station 200 is suspended, UE 100 is in an RRC inactive state.

[0026] Session management and mobility management for UE 100 are performed at the NAS layer, which is located higher than the RRC layer in UE 100. NAS signaling is transmitted between the NAS layer of UE 100 and the NAS layer of the core network device 300.

[0027] In addition to the wireless interface protocol, UE 100 also includes the application layer, etc.

[0028] (Wireless frame configuration) In 5G systems, downlink and uplink transmissions are configured within radio frames of 10ms duration. For example, radio frames are represented by System Frame Numbers (SFNs) from 0 to 1023. For example, a radio frame may consist of 10 subframes. For example, a subframe may be 1ms long. Furthermore, a subframe may include more than one time slot. For example, the number of symbols constituting a time slot is 14 in a standard CP (Cyclic Prefix) and 12 in an extended CP. Additionally, the number of time slots constituting a subframe varies depending on the configured subcarrier spacing. For example, for a standard CP, with a subcarrier spacing configured at 15kHz, the number of time slots per subframe is 1 (i.e., 14 symbols); with a subcarrier spacing configured at 30kHz, the number of time slots per subframe is 2 (i.e., 28 symbols); with a subcarrier spacing configured at 60kHz, the number of time slots per subframe is 4 (i.e., 56 symbols); and with a subcarrier spacing configured at 120kHz, the number of time slots per subframe is 8 (i.e., 112 symbols). Furthermore, for an extended CP, with a subcarrier spacing configured at 60kHz, the number of time slots per subframe is 4 (i.e., 48 symbols). That is, the number of time slots constituting one subframe is determined based on the subcarrier spacing configured by the base station 200. Additionally, the number of symbols constituting one subframe is determined based on the subcarrier spacing configured by the base station 200. That is, based on the subcarrier spacing configured by the base station 200, the number of symbols constituting a 1ms subframe is determined, and the length (length in the time direction) of each symbol varies.

[0029] (Determining the timing of PRACH transmission) The determination of the PRACH transmission timing is explained. For example, when performing a random access (RA) procedure, UE 100 determines the PRACH timing (or is referred to as the PRACH transmission timing).

[0030] UE 100 may execute the RA procedure, for example, if triggered by any of the following events: (a) initial access from the RRC idle state, (b) RRC connection re-establishment procedure, (c) arrival of downlink or uplink data during an RRC connection state when the uplink synchronization state is "asynchronous", (d) arrival of uplink data when no physical uplink control channel (PUCCH) resource is available for a scheduling request (SR), (e) SR failure, (f) a request via RRC during synchronization reconfiguration (e.g., handover), (g) an RRC connection recovery procedure from the RRC inactive state, (h) time adjustment for establishing a secondary timing advance group (TAG), (i) a request for other system information (Other SI), (j) beam failure recovery, and (k) consistent uplink listen-before-talk (UL) in the Sp cell. LBT failure, (l) small data transmission (SDT) in RRC inactive state, (m) location purpose during RRC connection state requiring RA procedure (e.g., when UE location needs to be timed in advance), etc.

[0031] During the RA process, UE 100 can, for example, use multiple predefined random access configurations and random access (RA) parameters included in System Information Block Type 1 (SIB 1) to determine the resources (i.e., PRACH timing) for PRACH transmission.

[0032] The random access (RA) configuration is defined by a table (RA configuration table) that associates the time-domain allocation configuration indicating the PRACH preamble format and PRACH timing with the PRACH configuration index. The UE 100 stores this table in advance.

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

[0034] Common RACH configuration information may include, for example, PRACH configuration indices (e.g., prach-ConfigurationIndex, msgA-PRACH-ConfigurationIndex(-r16)) and information on the number of PRACH transmission opportunities (e.g., msg1-FDM, msgA-RO-FDM(-r16)). “msg1-FDM” can indicate the number of PRACH transmission opportunities that are FDM-ized in a single instance. “msgA-RO-FDM” can indicate the number of msgA PRACH transmission opportunities that are frequency-division multiplexed in a single instance. The PRACH configuration index indicates which RA configuration among the multiple RA configurations defined in the RA configuration table is used for the PRACH transmission. UE 100 uses the RA configuration indicated by the PRACH configuration index to determine the PRACH opportunity.

[0035] In addition, UE 100 maps synchronization signals (SS) and physical broadcast channel (PBCH) block (SSB) indices (hereinafter sometimes referred to as SSB indices) to PRACH timings.

[0036] The SSB index uses parameters provided by RACH configuration public information (e.g., ssb-perRACH-OccasionAndCB-PreamblesPerSSB included in RACH-ConfigCommon and / or msgA-SSB-PerRACH-OccasionAndCB-PreamblesPerSSB included in RACH-ConfigCommonTwoStepRA) (e.g., the number of SSBs associated with a PRACH timing, the number of contention-based preambles for each SSB of each valid PRACH timing), and is mapped to valid PRACH timings in the following order, for example. First, the ascending order of the preamble index within a single PRACH timeframe. Second, the ascending order of the frequency resource index for frequency multiplexed PRACH occasions. Third, the ascending order of time resources for time-multiplexed PRACH occasions within a PRACH slot. Fourth, ascending order of the index used for PRACH slots.

[0037] An association period is specified for when UE 100 performs this mapping. The association period is the minimum value within the set determined by the PRACH configuration period. The association period begins in frame 0. Within the association period, a predetermined number of SSB indices are mapped to PRACH timings at least once. UE 100 obtains this predetermined number from information within SIB 1 or from serving cell configuration common information (e.g., ServingCellConfigCommon) (e.g., ssb-PositionsInBurst). Furthermore, within the set determined by the PRACH configuration period, the PRACH configuration period (ms) is associated with the association period (the number of PRACH configuration periods) in this table.

[0038] If, within the associated period, there exists a set of PRACH events or PRACH preambles that are not mapped to a predetermined number of SSB indices after the integer of the SSB index from the PRACH event to the mapping period, the SSB index is not mapped to that set of PRACH events or PRACH preambles.

[0039] The association pattern period includes one or more association periods. The association pattern period is determined such that the pattern between the PRACH timing and the SSB index repeats every 160 milliseconds. PRACH timings not associated with an SSB index after an integer association period are not used for PRACH transmission.

[0040] (SI Change) This section explains SI Modification.

[0041] When system information (part of it) is changed, network 10 first notifies UE 100 of the change. Network 10 may send the change notification to UE 100 in a specific change period (hereinafter, sometimes referred to as the first change period). Furthermore, the change notification may be sent multiple times during the first change period. In the next change period following the first change period (hereinafter, sometimes referred to as the second change period), network 10 sends the updated system information (i.e., the changed system information).

[0042] The summary of UE 100's actions during an SI change is explained in detail. UE 100 receives a DCI including a short message. This DCI may be a DCI with a CRC (also known as a CRC parity bit) scrambled using a Paging Radio Network Temporary Identifier (P-RNTI). Therefore, UE 100 instructs to update (change) the system information in the next change cycle (second change cycle) following the first change cycle after receiving the DCI.

[0043] The modification period is determined based on parameters included in the SIB 1 message (e.g., modificationPeriodCoeff, defaultPagingCycle). For example, the modification period (m) is determined by the following formula. The modification period is represented by the number of radio frames.

[0044] modification period m = modificationPeriodCoeff defaultPagingCycle In addition, "modificationPeriodCoeff" indicates the value used to calculate the actual modification period. "defaultPagingCycle" is the default paging period. The value of the default paging period corresponds to the number of radio frames (e.g., 32, 64, 128, 256). Furthermore, the boundaries of the modification period are defined by the SFN value where SFN mod m = 0.

[0045] Based on the change notification received in the first change cycle, UE 100 obtains new system information (i.e., updated system information) from the beginning of the second change cycle. UE 100 applies the previously obtained system information until it obtains new system information.

[0046] (Imagined scenario) In 3GPP, a standardization project for mobile communication systems, Network Energy Saving (NES) is being discussed. As one aspect of NES, a scheme for dynamic adaptation has been proposed, which involves dynamically changing the timing of the Physical Random Access Channel (PRACH) (hereinafter referred to as the PRACH period).

[0047] In the dynamic adaptation of PRACH timing, for example by changing the PRACH period based on downlink control information (DCI), the PRACH period can be changed at shorter time intervals compared to, for example, changing the PRACH period by updating system information blocks. As a result, network energy can be saved.

[0048] However, specific actions related to the dynamic adaptation of PRACH timing are not specified. Therefore, there is a concern that UE 100 may not be able to properly perform the dynamic adaptation of PRACH timing. Therefore, actions for enabling the proper performance of dynamic adaptation of PRACH timing will be described later.

[0049] For example, there is a concern that UE 100 may perform or not perform dynamic adaptation without knowing whether the (re)selected cell supports it. Furthermore, even if UE 100 attempts to change the PRACH period via DCI, it cannot determine how to change the PRACH period (e.g., it cannot determine which RA configuration to use as the changed RA configuration), thus raising concerns about PRACH transmission / reception failures between UE 100 and base station 200 (cell). Therefore, the actions for ensuring appropriate PRACH timing will be explained later.

[0050] Furthermore, when both mechanisms for changing the PRACH timing period through updating system information (system information block) and mechanisms for changing the PRACH timing period through DCI coexist, these two mechanisms may compete. In this case, it becomes unclear which mechanism UE 100 should follow to change the PRACH timing period, raising concerns about unexpected errors. Therefore, when UE 100 performs PRACH transmission, it is impossible to properly determine which change should be applied to the PRACH transmission, raising concerns about PRACH transmission / reception failures between UE 100 and base station 200 (cell). Therefore, the actions for dynamic adaptation to ensure proper execution of PRACH timing will be explained later.

[0051] (User equipment configuration) Reference Figure 4 The configuration of the UE 100 according to the implementation method will be described. The UE 100 includes a communication unit 110 and a control unit 120.

[0052] The communication unit 110 performs wireless communication with the base station 200 by transmitting and receiving wireless signals. The communication unit 110 includes at least one transmitting unit 111 and at least one receiving unit 112. The transmitting unit 111 and the receiving unit 112 can be configured to include multiple antennas and RF (Radio Frequency) circuitry. The antennas convert signals into radio waves and radiate these waves into space. Additionally, the antennas receive radio waves in space and convert them back into signals. The RF circuitry performs analog processing on the signals transmitted and received via the antennas. The RF circuitry may include high-frequency filters, amplifiers, modulators, and low-pass filters, etc.

[0053] The control unit 120 performs various controls within 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 can be controlled by the control unit 120. The control unit 120 may include at least one processor capable of executing a program and a memory storing the program. The processor can execute the program to perform the operations of the control unit 120. The control unit 120 may include a digital signal processor that performs digital processing of signals transmitted and received via an antenna and RF circuitry. This digital processing includes processing of the RAN protocol stack. Furthermore, the memory stores the program executed by the processor, parameters related to the program, and data related to the program. The memory may include at least one of ROM (Read Only Memory), EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory), RAM (Random Access Memory), and flash memory. All or part of the memory may be included within the processor.

[0054] In the UE 100 configured in this way, the receiving unit 112 receives updated system information and control information from the base station 200. The updated system information indicates a change in the PRACH timing period, and the control information is information indicating the change in the PRACH timing period and is carried by lower-layer signaling below the RRC layer. The control unit 120 prioritizes one of the updated system information and control information according to priority information received from the base station 200 or a pre-defined rule, and changes the PRACH period based on this priority information. Therefore, when performing PRACH transmission, the UE 100 can appropriately determine which change should be applied to the PRACH transmission according to the priority information received from the base station 200 or the pre-defined rule. The applicable change can be shared between the UE 100 and the base station 200 (cell), and PRACH transmission / reception failures can be suppressed. As a result, dynamic adaptation can be appropriately performed. Furthermore, the priority information is used to determine which of the updated system information and control information takes priority. Additionally, the pre-defined rule is a rule used to determine which of the updated system information and control information takes priority.

[0055] (Base station configuration) Reference Figure 5The configuration of the base station 200 according to the implementation method will be described. The base station 200 includes a communication unit 210, a network communication unit 220, and a control unit 230.

[0056] Communication unit 210, for example, receives wireless signals from UE 100 and transmits wireless signals to UE 100. Communication unit 210 includes at least one transmitting unit 211 and at least one receiving unit 212. Transmitting unit 211 and receiving unit 212 may be configured to include RF circuitry. The RF circuitry performs analog processing of signals transmitted and received via antenna. The RF circuitry may include high-frequency filters, amplifiers, modulators, and low-pass filters, etc.

[0057] The network communication unit 220 transmits and receives signals with the network. For example, the network communication unit 220 receives signals from neighboring base stations connected via an Xn interface, which serves as an inter-base station interface, and transmits signals to neighboring base stations. Additionally, the network communication unit 220 receives signals from, for example, a core network device 300 connected via an NG interface, and transmits signals to the core network device 300.

[0058] Control unit 230 performs various controls within base station 200. For example, control unit 230 controls communication with UE 100 via communication unit 210. Additionally, control unit 230 controls communication with nodes (e.g., neighboring base stations, core network device 300) via network communication unit 220. The operation of base station 200 described above and below can be controlled by control unit 230. Control unit 230 may include at least one processor capable of executing a program and a memory storing the program. The processor can execute the program to perform the operations of control unit 230. Control unit 230 may include a digital signal processor that performs digital processing of signals transmitted and received via antennas and RF circuitry. This digital processing includes processing of the RAN protocol stack. Furthermore, the memory stores the program executed by the processor, parameters related to the program, and data related to the program. All or part of the memory may be included within the processor.

[0059] In this base station 200 configuration, the transmitting unit 211 sends updated system information and control information to the UE 100. The updated system information indicates a change in the PRACH timing period, and the control information, which also indicates a change in the PRACH timing period, is carried by lower-layer signaling below the RRC layer. The transmitting unit 211 sends priority information to the UE 100, which is used by the UE 100 to determine which information—the updated system information or the control information—takes priority. Therefore, when performing PRACH transmission, the UE 100 can appropriately determine which change to apply for PRACH transmission based on the priority information received from the base station 200. The applicable changes can be shared between the UE 100 and the base station 200 (cell), suppressing PRACH transmission / reception failures. As a result, dynamic adaptation can be appropriately performed.

[0060] (Example of the first action) Reference Figures 5 to 9 The first action example is explained. Sometimes, explanations that have already appeared are omitted.

[0061] UE 100 can be in an RRC idle state or an RRC inactive state with the cell managed by base station 200. Additionally, UE 100 can be in an RRC connected state with the cell. The cell can be the cell where UE 100 is camped, or it can be a cell (re)selected by UE 100. The cell can be a cell with which UE 100 has established an RRC connection. Furthermore, in this example, it is assumed that UE 100 is in an RRC idle state, and the explanation will continue.

[0062] Furthermore, for UE 100, communication with base station 200 can be communication with the cell. Therefore, for UE 100, receiving information / messages from base station 200 can be receiving information / messages from the cell, and sending information / messages to base station 200 can be sending information / messages to the cell.

[0063] Step S101: The transmitting unit 211 of base station 200 sends a System Information Block Type 1 (SIB 1) message to UE 100. The transmitting unit 211 of base station 200 broadcasts the SIB 1 message. The receiving unit 112 of UE 100 receives the SIB 1 message from base station 200 (cell).

[0064] The SIB 1 message includes information related to assessing whether the UE 100 is allowed to access the cell. The SIB 1 message may include support information related to the cell's dynamic adaptation capabilities. The control unit 230 of the base station 200 can control whether to include support information in the SIB 1 message based on whether the cell supports dynamic adaptation.

[0065] Support information can indicate whether a cell supports dynamic adaptation. If the cell supports dynamic adaptation, the support information indicates that the cell supports dynamic adaptation. Conversely, if the cell does not support dynamic adaptation, the support information indicates that the cell does not support dynamic adaptation. Additionally, the support information can indicate whether a cell supports dynamic adaptation based on whether it is included in the SIB 1 message.

[0066] The control unit 230 of base station 200 can control whether to include support information in the SIB 1 message based on whether the cell of base station 200 supports dynamic adaptation. For example, if the cell supports dynamic adaptation, the control unit 230 of base station 200 can (always) include support information indicating that the cell supports dynamic adaptation (e.g., "true") in the SIB 1 message. Alternatively, the control unit 230 can omit support information indicating that the cell does not support dynamic adaptation in the SIB 1 message. In this case, the control unit 120 of UE 100 can determine that the cell supports dynamic adaptation by omitting the support information in the SIB 1 message.

[0067] Furthermore, if the cell does not support dynamic adaptation, the control unit 230 of base station 200 may (always) include support information indicating that the cell does not support dynamic adaptation (e.g., "false") in the SIB 1 message. Alternatively, the control unit 230 may omit the support information indicating that the cell supports dynamic adaptation in the SIB 1 message. In this case, the control unit 120 of UE 100 can determine that the cell does not support dynamic adaptation by omitting the support information in the SIB 1 message.

[0068] Supporting information can indicate whether dynamic adaptation is enabled or disabled. Supporting information can also indicate whether dynamic adaptation (its execution) is permitted within a cell.

[0069] Here, dynamic adaptation may be referred to as dynamic RACH adaptation, for example. Dynamic adaptation may be, for example, at least any of the following actions (or definitions). UE 100 switches RA configuration via signaling from a lower layer below the RRC layer. UE 100 supports multiple PRACH configurations. • Configure multiple PRACH configurations for a single cell to UE 100 • Configure multiple PRACH configurations for a single bandwidth portion (BWP) to UE 100 • Configure multiple PRACH configurations for a single subcarrier interval to UE 100 • Configure multiple PRACH configurations for a single component carrier to UE 100 • Changes to configuration and / or parameters used for PRACH transport

[0070] In addition, the configuration and / or parameters used for PRACH transmission may be, for example, at least one of the following: PRACH preamble index, preamble SCS (Subcarrier Spcaing), PRACH resources (time resources, frequency resources), and / or the period (cycle) of PRACH timing.

[0071] In addition to support information, base station 200 may also include configuration information related to dynamic adaptation (hereinafter referred to as DA configuration information) in SIB 1 message.

[0072] Furthermore, when the cell supports dynamic adaptation, the transmitting unit 211 of the base station 200 can send a dedicated PDCCH configuration to the UE 100 for monitoring changes that trigger RA configuration. The receiving unit 112 of the UE 100 can receive the dedicated PDCCH configuration from the base station 200.

[0073] The control unit 230 of base station 200 may include a dedicated PDCCH configuration, for example, in a system information block (e.g., SIBx). Base station 200 may also include the dedicated PDCCH configuration in a specific (dedicated) RRC message. The dedicated PDCCH configuration may be information used to configure a search space (common search space) and / or CORESET dedicated to dynamic adaptation.

[0074] Furthermore, when the cell supports dynamic adaptation, the transmitting unit 211 of the base station 200 can send configuration information to the UE 100. This configuration information is used to configure multiple RA configurations for determining the PRACH timing in the UE 100. The UE 100 receives this configuration information. The control unit 230 of the UE 100 can perform control based on this configuration information, thereby configuring multiple RA configurations in the UE 100.

[0075] Furthermore, multiple RA configurations may (only) include general RA configurations that are not dedicated RA configurations, may (only) include dedicated RA configurations described later, or may include a combination of general RA configurations and dedicated RA configurations. Additionally, a general RA configuration may be, for example, a configuration that can also be configured for UE 100 (which may be referred to as a legacy UE) that does not support dynamic adaptation (i.e., does not have the ability to dynamically adapt). A general RA configuration may, for example, be an RA configuration specified in a version of the technical specification document prior to the version that supports dynamic adaptation.

[0076] Step S102: The control unit 120 of UE 100 performs a support determination. Specifically, the control unit 120 determines whether the cell supports dynamic adaptation. For example, as described above, the control unit 120 can determine whether the cell supports dynamic adaptation based on support information. The control unit 120 can also determine whether the cell supports dynamic adaptation based on whether the SIB 1 message includes support information.

[0077] like Figure 6 As shown, for example, in step S121, if the SIB 1 message includes support information indicating that the cell supports dynamic adaptation, the control unit 120 can perform the processing of step S122. On the other hand, if the SIB 1 message does not include support information indicating that the cell supports dynamic adaptation, the control unit 120 can perform the processing of step S123.

[0078] In step S122, the control unit 120 determines that the cell supports dynamic adaptation. When the cell supports dynamic adaptation, the control unit 120 can perform dynamic adaptation.

[0079] In step S123, the control unit 120 determines that the cell does not support dynamic adaptation. If the cell does not support dynamic adaptation, the control unit 120 may not perform dynamic adaptation.

[0080] Step S103: The transmitting unit 211 of base station 200 sends lower-layer signaling (below the RRC layer) to UE 100. The receiving unit 112 of UE 100 receives the lower-layer signaling from base station 200. The lower-layer signaling may be DCI. The lower-layer signaling may be a PDCCH carrying DCI. The lower-layer signaling may be signaling in the MAC layer (e.g., MAC CE). In this example, the lower-layer signaling is set to DCI, and the explanation continues.

[0081] When the cell of base station 200 supports dynamic adaptation, the control unit 230 of base station 200 may send a DCI (hereinafter sometimes referred to as a specific DCI) that includes a specific field (or is configured with a specific field) for changing the period of PRACH timing. On the other hand, when the cell of base station 200 does not support dynamic adaptation, the control unit 230 may send a DCI that does not include a specific field (or is not configured with a specific field) (hereinafter referred to as a normal DCI).

[0082] The specific field can be a field used to change the period of PRACH timing. Alternatively, the specific field can be, for example, a field used to change the random access configuration. The specific field can include specific information. Specific information can be information used to change the period of PRACH timing. Alternatively, specific information can be information used to change the random access configuration. Details of the specific information are described later.

[0083] When a dedicated PDCCH configuration is configured for UE 100, the transmitting unit 211 of base station 200 can transmit a specific DCI in a search space and / or CORESET dedicated to dynamic adaptation. Alternatively, the transmitting unit 211 can transmit a normal DCI in a search space and / or CORESET configured by the normal PDCCH configuration.

[0084] Furthermore, a specific DCI can be a DCI with an added CRC (also known as a CRC parity bit) scrambled using a predetermined Radio Network Temporary Identifier (RNTI). A specific DCI can be information that triggers a change in the RA configuration. A PDCCH including a specific DCI can be called a PDCCH accompanied by a predetermined RNTI, or a PDCCH addressed to a predetermined RNTI. The predetermined RNTI can be an SI-RNTI, P-RNTI, RA-RNTI, and / or an RNTI dedicated to dynamic adaptation.

[0085] Furthermore, in UE 100, each of the more than one DL BWP can be configured to monitor the search space and CORESET of a specific DCI. In this case, the control unit 120 of UE 100 can control the execution of (based on) dynamic adaptation (PRACH transmission) in the uplink bandwidth portion (UL BWP) corresponding to the DL BWP that received the DCI.

[0086] Step S104: The control unit 120 of UE 100 can perform DCI determination. Specifically, the control unit 120 can determine whether the received DCI is a normal DCI or a specific DCI. In addition, when a predetermined signaling of a layer lower than the RRC layer is received, the control unit 120 can determine whether a specific field is included in the predetermined signaling.

[0087] When a predetermined signaling message (e.g., DCI) is received from a cell, control unit 120 can determine, based on support information, whether a specific field is included in the received predetermined signaling message (e.g., DCI). If, based on the support information, it is determined that the cell supports dynamic adaptation, control unit 120 can determine that the specific field is included in the predetermined signaling message. Control unit 230 can determine that the received DCI is a specific DCI. On the other hand, if, based on the support information, it is determined that the cell does not support dynamic adaptation, control unit 120 can determine that the specific field is not included in the predetermined signaling message. Control unit 230 can determine that the received DCI is a normal DCI.

[0088] Furthermore, if the PDCCH is successfully decoded using a predetermined RNTI (e.g., an RNTI specifically for dynamic adaptation), the control unit 120 can determine that the DCI included (carried) in the PDCCH is a specific DCI.

[0089] In addition, when specific field information is received from the cell, the control unit 120 can determine whether the specific field is included in the received predetermined signaling (e.g., DCI) based on the specific field information.

[0090] Specific field information can be information indicating whether a specific field is included in a predetermined signaling (e.g., DCI). In this case, control unit 120 determines that the specific field is included in the predetermined signaling (e.g., DCI). Therefore, control unit 120 can determine that the received DCI is a specific DCI. On the other hand, specific field information can also indicate that a specific field is not included in the predetermined signaling (e.g., DCI). In this case, control unit 120 determines that the specific field is not included in the predetermined signaling (e.g., DCI). Therefore, control unit 120 can determine that the received DCI is a normal DCI.

[0091] Furthermore, the transmitting unit 211 of the base station 200 can send specific field information to the UE 100. The transmitting unit 211 can include the specific field information, for example, in a Radio Resource Control (RRC) message. The control unit 230 of the base station 200 can include the specific field information, for example, in a specific Radio Resource Control (RRC) message sent to the UE 100 (e.g., an RRC reconfiguration message). The control unit 230 can be included in a System Information Block (SIB) transmitted via broadcast.

[0092] When a dedicated PDCCH configuration is configured, the control unit 120 of UE 100 can determine that a DCI received in the search space and / or CORESET dedicated to dynamic adaptation is a specific DCI. Furthermore, the control unit 120 can determine that a DCI received in the search space and / or CORESET configured by the normal PDCCH configuration is a normal DCI.

[0093] Furthermore, the control unit 120 can perform the aforementioned determination before receiving the DCI. Based on the determination result, the control unit 120 can determine whether the received DCI is a normal DCI or a specific DCI. The control unit 120 can perform the determination at the timing of receiving support information. The control unit 120 can perform the determination at the timing of receiving specific field information.

[0094] In this action example, it is assumed that UE 100 determines that the received DCI is a specific DCI, and the explanation continues.

[0095] Step S105: The control unit 120 of UE 100 determines the PRACH timing. Additionally, the control unit 120 can determine the period of the PRACH timing. For example, if the cell supports dynamic adaptation, the control unit 120 can execute at least one of the following methods.

[0096] In the first method, the control unit 120 can modify the RA configuration used to determine the PRACH timing based on low-level signaling (e.g., DCI). The control unit 120 can determine the cycle of the modified PRACH timing based on the modified RA configuration. The control unit 120 can determine the cycle of the modified PRACH timing based on specific information included in a specific field.

[0097] Specific information may include, for example, an index (e.g., a PRACH config index) indicating the period of the changed PRACH timing. Control unit 120 can change to the RA configuration indicated by the index. When multiple RA configurations are configured in UE 100, control unit 230 of UE 100 can change to the RA configuration indicated by the index among the multiple configured RA configurations.

[0098] Additionally, specific information may include information specifying a dedicated RA configuration, which includes a configuration dedicated to dynamic adaptation and related to the PRACH timing cycle. This information may, for example, indicate the dedicated RA configuration. The control unit 120 can change to the dedicated RA configuration indicated by the index. The control unit 120 can determine the changed PRACH timing cycle based on the dedicated RA configuration.

[0099] Furthermore, the dedicated RA configuration is specified, for example, by a table (e.g., a dedicated RA configuration table) that associates the time-domain allocation configuration indicating the PRACH preamble format and PRACH timing with a dedicated PRACH configuration index. The UE 100 may pre-store the dedicated RA configuration table. When the dedicated RA configuration is indicated by an index, the UE 100 may determine the dedicated RA configuration based on the dedicated RA configuration table instead of the RA configuration table. When multiple RA configurations are configured in the UE 100, the control unit 230 of the UE 100 may change to the specified dedicated RA configuration among the multiple configured RA configurations.

[0100] When multiple RA configurations are configured in UE 100, the control unit 120 of UE 100 can determine the number of bits in a specific field based on the number of RA configurations. For example, when two or fewer RA configurations are configured in UE 100, the number of bits in the specific field can be 1. When four or fewer RA configurations are configured in UE 100, the number of bits in the specific field can be 2. When eight or fewer RA configurations are configured in UE 100, the number of bits in the specific field can be 3. The control unit 120 can indicate a changed RA configuration through specific information included in a specific field represented by one or more bit counts.

[0101] like Figure 7 A, Figure 7 B and Figure 8 As shown, assume that control unit 120 applies (or uses, configures) the RA configuration associated with the PRACH configuration index of instruction 34. Assume that in this RA configuration, the PRACH configuration period is 40ms. Control unit 120 determines the radio frame in which a PRACH opportunity is allocated during the PRACH configuration period. Control unit 120 determines the time slot in the determined radio frame where the PRACH opportunity is allocated, and the symbol in which the PRACH opportunity is allocated within that time slot.

[0102] Subsequently, for example, in the case of an index indicating specific information 38 included in a specific field of a received specific DCI, the control unit 120 applies the RA configuration change (application) to the RA configuration associated with the PRACH configuration index of the indication 38. Therefore, the specific information (within) a specific DCI could be an indication to change the PRACH configuration index applied to the UE 100 from 34 to 38. Assume that in the changed RA configuration, the PRACH configuration period is 20ms. Similarly, the control unit 120 determines the radio frame for which the PRACH timing is allocated, the time slot for which the PRACH timing is allocated, and the symbol for which the PRACH timing is allocated.

[0103] In the second method, the control unit 120 can determine the changed PRACH timing period based on the configuration value used to adjust the PRACH timing period.

[0104] For example, the control unit 120 can calculate a PRACH timing period that differs from the PRACH timing period based on the configured RA configuration, based on the configuration value. The control unit 120 can then determine the calculated PRACH timing period as the changed PRACH timing period. Alternatively, the control unit 120 can calculate a PRACH timing period that differs from the PRACH timing period based on the RA configuration (or dedicated RA configuration) determined by the first method, based on the configuration value.

[0105] The configuration value can be a scaling factor for periodic changes. This scaling factor can be a periodic scaling factor that extends the RA configuration (or dedicated RA configuration) as a baseline. The control unit 230 of base station 200 can include the configuration value, for example, in a specific DCI. The receiving unit 112 of UE 100 can receive the configuration value from base station 200.

[0106] The control unit 120 of UE 100 can determine the timing for changing the RA configuration. That is, the control unit 120 can determine the timing for applying the changed RA configuration. The control unit 120 can also determine the timing of the period for changing the PRACH timing. The control unit 120 can change the RA configuration, for example, by at least one of the following methods.

[0107] In the first method, the control unit 120 can change the RA configuration (determine the timing of changing the RA configuration) based on a change cycle (hereinafter, sometimes referred to as the DA change cycle) related to the change of the PRACH timing cycle based on dynamic adaptation. For example, Figure 7 A and Figure 9 As shown, for example, the DA change cycle can be repeated periodically. The control unit 120 can change the RA configuration at or after the boundary between a specific DA change cycle (e.g., the first DA change cycle MP1) and the next DA change cycle (e.g., the second DA change cycle MP2). When a specific DCI is received in the first DA change cycle MP1, the control unit 120 can change the RA configuration in the second DA change cycle MP2. Therefore, the control unit 120 determines to change the RA configuration in the second DA change cycle MP2.

[0108] The DA change cycle can be defined or configured based on the PRACH configuration cycle, association cycle, and / or association mode cycle. The DA change cycle can, for example, be an integer (natural number) multiple of the PRACH configuration cycle, association cycle, and / or association mode cycle. The control unit 120 can determine the DA change cycle based on the PRACH configuration cycle, association cycle, and / or association mode cycle. The second DA change cycle MP2 can be defined or configured based on the PRACH configuration cycle, association cycle, and / or association mode cycle in the changed RA configuration and / or dedicated RA configuration.

[0109] In the second method, the control unit 120 can change the RA configuration after a minimum period has elapsed since receiving a specific DCI. Therefore, the control unit 120 determines to change the RA configuration after a minimum period has elapsed since receiving the specific DCI.

[0110] The minimum period is the minimum period during which UE 100 is not expected to change its RA configuration after receiving lower-layer signaling (specific DCI). The minimum period can be specified, for example, based on the time required for UE 100 to change its RA configuration. Alternatively, the minimum period can be specified, for example, based on the time (system frame number, subframe, timeslot, and / or symbol) of receiving the lower-layer signaling (specific DCI) and the cell-specific scheduling offset (cellSpecificKoffset), the UL BWP for PRACH transmission, and / or the SCS configuration (preamble SCS) for PRACH transmission. Furthermore, "cellSpecificKoffset" is the scheduling offset for changing timing relationships in NTN (Non-Terrestrial Network).

[0111] Furthermore, the control unit 120 can determine valid and / or invalid PRACH timings during dynamic adaptation. The control unit 120 can determine valid and / or invalid PRACH timings, for example, based on pre-defined information (e.g., rules specified in technical specification documents).

[0112] A valid PRACH timing is a PRACH timing in which PRACH transmission is effective. An invalid PRACH timing is a PRACH timing in which PRACH transmission is invalid. Therefore, UE 100 cannot transmit PRACH during an invalid PRACH timing. UE 100 can only perform PRACH transmission during valid PRACH timings.

[0113] The receiving unit 112 of UE 100 can receive information from base station 200 indicating valid PRACH timings and / or invalid PRACH timings. For example, this information may be included in DA configuration information, in a specific RRC message to UE 100, or in specific information (i.e., a specific field).

[0114] Based on this information, the control unit 120 can determine valid and / or invalid PRACH timings. This information can specify valid and / or invalid PRACH timings. For example, this information may include a PRACH mask index. The control unit 120 can set the PRACH timing indicated by this index as an invalid PRACH timing.

[0115] Furthermore, the control unit 120 can identify PRACH timings with the same timing as those determined by changing the PRACH timing cycle from among one or more PRACH timings, as invalid PRACH timings. Therefore, the control unit 120 can identify PRACH timings with different timings from those determined by changing the PRACH timing cycle from among one or more PRACH timings, as valid PRACH timings. The control unit 120 can determine whether to set the aforementioned PRACH timings with the same timing as valid or invalid PRACH timings based on information indicating valid and / or invalid PRACH timings.

[0116] like Figure 8 As shown, assuming that in the RA configuration before the change, the fourth radio frame was determined to be the radio frame to be assigned a PRACH timing. Next, assuming that in the RA configuration after the change, the control unit 120 determines the second and fourth radio frames to be the radio frames to be assigned a PRACH timing. In this case, since the fourth radio frame is assigned a PRACH timing before and after the RA configuration, the control unit 120 sets the PRACH timing assigned to the fourth radio frame to an invalid PRACH timing. Therefore, it is possible to ensure that the fourth radio frame is set as the PRACH timing for the existing UE 100 and the UE 100 that does not perform dynamic adaptation.

[0117] As described above, the control unit 120 of UE 100 can, for example, determine the period of the changed PRACH timing based on the changed RA configuration. The period of the PRACH timing can be any of the PRACH configuration period, the association period, and / or the association mode period. The period of the PRACH timing can also be the DA change period.

[0118] Furthermore, when the received DCI is a normal DCI, the control unit 120 of UE 100 can determine the PRACH timing based on the already configured RA. The control unit 120 can maintain the PRACH timing period without changing the RA configuration.

[0119] Furthermore, when the RA configuration (or the PRACH timing period) is changed, the control unit 120 of the UE 100 can remap the SSB (SSB index) to the PRACH timing. The control unit 120 can consider the PRACH timing period, the PRACH configuration period, the association period, and / or the association mode period to map the SSB (SSB index) to the PRACH timing.

[0120] The SSB can be a CD-SSB (Cell-defining SSB) and / or an NCD (Non-cell-defining SSB). UE 100 can always perform dynamic adaptation based on the CD-SSB. The control unit 120 of UE 100 can include information configuring the subcarrier spacing for the SSB in the serving cell and / or the downlink bandwidth portion (DLBWP) in the SIB or in the RRC message.

[0121] Additionally, information configuring the subcarrier spacing for PRACH can be included in the RACH configuration information (e.g., RACH-config common). This information can be included in predefined configuration information within the RACH configuration information (e.g., BWP-UplinkCommon). "BWP-UplinkCommon" can be information used to configure common parameters for the uplink BWP. The subcarrier spacing can be configured for each of one or more DL BWPs (e.g., initial DL BWP and / or dedicated DL BWP) and one or more UL BWPs (e.g., initial UL BWP and / or dedicated UL BWP).

[0122] Furthermore, if the information used to configure the SSB is not included in the SIB (or RRC message), the control unit 120 of the UE100 can perform dynamic adaptation based on the SSB configuration pre-defined in the technical specification document.

[0123] Step S106: The transmitting unit 111 of UE 100 performs PRACH transmission at the determined PRACH timing. The receiving unit 212 of base station 200 receives PRACH from UE 100.

[0124] Here, the effective time period can be configured in the changed RA configuration. For example, the case where the control unit 120 of UE 100 changes the RA configuration from the first RA configuration to the second RA configuration will be explained.

[0125] like Figure 9 As shown, when the control unit 120 receives a specific DCI in the first DA change cycle MP1, the control unit 120 applies the second RA configuration in the second DA change cycle MP2. The control unit 120 determines the PRACH timing (cycle) according to the second RA configuration.

[0126] Subsequently, in the third DA change cycle MP3, the control unit 120 applies the first RA configuration. Therefore, the control unit 120 determines the PRACH timing (cycle) according to the first RA configuration. That is, if a predetermined effective period has elapsed since the change to the second RA configuration, the control unit 120 changes from the second RA configuration back to the first RA configuration. The control unit 120 then performs control to return to the RA configuration before the change.

[0127] The valid time period can be defined or configured based on the PRACH configuration cycle, association cycle, and / or association mode cycle. The valid time period can, for example, be an integer (natural number) multiple of the PRACH configuration cycle, association cycle, and / or association mode cycle. The control unit 120 can determine the valid time period based on the PRACH configuration cycle, association cycle, and / or association mode cycle. Figure 9 In this context, the scheduled effective time period can be one PRACH configuration cycle (one period).

[0128] The receiving unit 112 of UE 100 can receive information for a specified valid time period from base station 200. For example, the information for the specified valid time period may be included in DA configuration information, may be included in a specific RRC message to UE 100, or may be included in specific information (i.e., specific fields).

[0129] Upon receiving information specifying a valid time period, the control unit 120 of the UE 100 can configure the valid time period. That is, the control unit 120 can perform control based on the valid time period. Alternatively, upon receiving information specifying a valid time period and receiving indication information for configuring a valid time period from the base station 200, the control unit 120 can perform control based on the valid time period. This indication information may, for example, be included in a specific field.

[0130] Furthermore, the default value for the valid time period can be predefined. Alternatively, the information specifying the valid time period may include a default value in addition to indicating a specific value for the valid time period. The control unit 120 of the UE 100 may pre-store the default value for the valid time period. If the information specifying the valid time period is not received, the control unit 120 may configure the default value as the valid time period. Alternatively, if the indication information is not received, the control unit 120 may configure the default value as the valid time period.

[0131] Furthermore, the control unit 120 of UE 100 controls changes to the RA configuration (i.e., the period of PRACH timing) based on the effective time period, but is not limited to this. For example, UE 100 can change the RA configuration (or revert to the original RA configuration) through direct instructions from base station 200.

[0132] The transmitting unit 211 of base station 200 can send low-level signaling (e.g., DCI) to UE 100 instructing UE 100 to change (or revert) to the default RA configuration. The control unit 120 of UE 100 can change to the default RA configuration based on the received signaling (e.g., DCI). The DCI can be a specific DCI. For example, a specific field of the specific DCI may include information indicating a return to the default RA configuration. The control unit 120 can change to the default RA configuration based on this information. Alternatively, the DCI can be a general DCI. The control unit 120 can change to the default RA configuration based on receiving a general DCI.

[0133] Furthermore, the default RA configuration can be, for example, the general RA configuration. Therefore, the default RA configuration can be included in the SIB 1 message. Alternatively, the default RA configuration can be a dedicated default RA configuration. Additionally, the default RA configuration can be predefined in a technical specification document, for example. The control unit 120 can store this default RA configuration. If the default RA configuration is not configured from the base station 200 to the UE 100, the control unit 120 can change to the predefined default RA configuration.

[0134] As described above, the transmitting unit 211 of base station 200 sends an SIB 1 message to UE 100. Control unit 230 controls whether to include support information indicating whether the cell supports dynamic adaptation in the SIB 1 message, based on whether the cell supports dynamic adaptation by changing the PRACH timing period through signaling at a lower layer below the RRC layer. The receiving unit 112 of UE 100 receives the SIB 1 message from the cell, which includes information related to assessing whether UE 100 is allowed to access the cell. Control unit 120 controls dynamic adaptation, which changes the PRACH timing period through signaling at a lower layer below the RRC layer. If support information indicating that the cell supports dynamic adaptation is included in the SIB 1 message, control unit 120 determines that the cell supports dynamic adaptation based on the support information. Therefore, UE 100 can determine that the cell supports dynamic adaptation. As a result, UE 100 can appropriately perform dynamic adaptation in cells that support dynamic adaptation.

[0135] Furthermore, when the cell supports dynamic adaptation, the control unit 120 can modify the RA configuration used to determine the PRACH timing based on lower-layer signaling. The control unit 120 can then determine the modified PRACH timing based on the modified RA configuration. Thus, the base station 200 can appropriately control dynamic adaptation by changing the period of the PRACH timing through modifying the RA configuration.

[0136] Furthermore, the receiving unit 112 can receive DCI, which includes a specific field for changing the period of PRACH timing, as low-layer signaling. The control unit 120 can determine the changed PRACH timing period based on the specific information included in the specific field. Thus, the base station 200 can appropriately control dynamic adaptation through DCI.

[0137] Additionally, specific information may include an index indicating the RA configuration related to the period of the changed PRACH timing. The control unit 120 can change to the RA configuration indicated by the index. Thus, the UE 100 can understand the RA configuration that should be changed through dynamic adaptation. Therefore, the UE 100 can appropriately control dynamic adaptation.

[0138] Additionally, the specific information may include information specifying a dedicated RA configuration, which includes a configuration dedicated to dynamic adaptation and related to the period of PRACH timing. The control unit 120 can determine the changed PRACH timing period based on the dedicated RA configuration. Thus, the UE 100 can appropriately control dynamic adaptation by using the dedicated RA configuration.

[0139] Furthermore, when the cell supports dynamic adaptation, the receiving unit 112 can receive a configuration value used to adjust the PRACH timing period via lower-layer signaling. The control unit 120 can determine the changed PRACH timing period based on the configuration value. Thus, even without changing the RA configuration, the UE 100 can change the PRACH timing period.

[0140] Furthermore, when the cell supports dynamic adaptation, the receiving unit 112 can receive a dedicated PDCCH configuration used to monitor DCIs that trigger changes in the RA configuration. The receiving unit 112 can receive DCIs as lower-layer signaling based on the dedicated PDCCH configuration. Therefore, the UE 100 can determine that the received DCI is a specific DCI. The UE 100 can distinguish between normal DCIs and specific DCIs, and can appropriately control dynamic adaptation.

[0141] Furthermore, the change cycle related to the periodic change of the PRACH timing based on dynamic adaptation can be repeated periodically. The control unit 120 can change the RA configuration in the next change cycle after receiving lower-layer signaling. Therefore, when multiple UEs 100 are configured with dynamic adaptation, the base station 200 can change the RA configuration of each UE 100 simultaneously, instead of changing the RA configuration at specific timings for each UE 100. As a result, the control load of the base station 200 can be reduced.

[0142] Furthermore, the control unit 120 can change the RA configuration after a minimum period, which is the period during which the UE 100 is not expected to change its RA configuration, from the time the lower-layer signaling is received. Therefore, by preventing the RA configuration from being immediately changed according to the capabilities of the UE 100, PRACH transmission / reception failures caused by differences in the RA configuration applied between the UE 100 and the base station 200 can be suppressed.

[0143] Furthermore, the control unit 120 can identify a PRACH timing that is at the same time as a PRACH timing determined based on the period of the previous PRACH timing, from among one or more PRACH timings determined by changing the PRACH timing period, as an invalid PRACH timing. This allows for different PRACH timings for UE 100 performing dynamic adaptation, existing UE 100, and UE 100 not performing dynamic adaptation. As a result, it is difficult for UE 100s performing PRACH transmissions in a specific PRACH timing to be concentrated, the RACH load of the cell will not increase, and the PRACH success rate can be improved.

[0144] Furthermore, the control unit 120 can change the RA configuration from the first RA configuration to the second RA configuration. If a predetermined valid period has elapsed since the change to the second RA configuration, the control unit 120 can change the RA configuration back to the first RA configuration. Therefore, even without an instruction from the base station 200 to return the RA configuration of the UE 100 to its original state, the UE 100 can still return the RA configuration to its original state.

[0145] Furthermore, when receiving predetermined signaling from a cell at a layer lower than the RRC layer, the control unit 120 can determine, based on supporting information, whether the received predetermined signaling includes a specific field for the period used to change the PRACH timing. Thus, the UE 100 can determine whether the specific field is included based on the SIB 1 message.

[0146] Additionally, the receiving unit 112 can receive specific field information from the cell, which indicates whether a specific field for changing the PRACH timing period is included in the predetermined signaling of a layer below the RRC layer. When predetermined signaling is received from the cell, the control unit 120 can determine whether the received predetermined signaling includes the specific field based on the specific field information. Therefore, based on the specific field information, the UE 100 and the base station 200 can control whether the specific field is included in the predetermined signaling, even when the cell supports dynamic adaptation. The base station 200 can flexibly control dynamic adaptation.

[0147] Additionally, the receiving unit 112 can receive configuration information from the cell for configuring multiple RA configurations to determine the PRACH timing for the UE 100. The control unit 120 can determine the number of bits for a specific field based on the number of multiple RA configurations configured by the configuration information. Thus, the UE 100 can know the number of bits for a specific field by receiving the configuration information.

[0148] (Example of the second action) Reference Figure 10 as well as Figure 11 The second action example will be explained below. Sometimes, descriptions that have already appeared are omitted. In this action example, UE 100 determines which information, the updated system information or the control information (specific DCI), takes precedence.

[0149] In addition, such as Figure 11 As shown, base station 200 sends system information (SI) to UE 100 during a specific change period (first change period). UE 100 uses, for example, the information included in the system information received from base station 200 to perform communication with base station 200 (the cell).

[0150] Step S201: The transmitting unit 211 of the base station 200 can send priority information to the UE 100. The receiving unit 112 of the UE 100 can receive the priority information from the base station 200.

[0151] Priority information may be included, for example, in system information. Priority information may be included in SIB 1 messages. Priority information may be included in DA configuration information related to dynamic adaptation. Additionally, priority information may be included, for example, in specific RRC messages sent to UE 100.

[0152] Priority information indicates whether updating system information takes precedence over control information. This control information is periodic information about the timing of PRACH changes and is carried by lower-level signaling below the RRC layer. This control information can be, for example, a specific DCI. The following explanation assumes the control information is a specific DCI.

[0153] Priority information can indicate, for example, that updating system information takes precedence over a specific DCI. Priority information can also indicate that updating system information does not take precedence over a specific DCI.

[0154] The presence or absence of priority information in the fields where priority information can be set within the information received from base station 200 indicates that updating system information takes precedence over a specific DCI. Conversely, the presence or absence of priority information in the fields where priority information can be set within the information received from base station 200 indicates that updating system information does not take precedence over a specific DCI. Control unit 120 can determine whether updating system information takes precedence over a specific DCI by determining whether priority information exists in the fields where priority information can be set within the information received from base station 200.

[0155] Step S202: The transmitting unit 211 of base station 200 sends a DCI including a short message to UE 100 via PDCCH. The receiving unit 112 of UE 100 receives the DCI from base station 200 via PDCCH.

[0156] When updating (changing) the System Information (SI), the control unit 230 of the base station 200 can send the DCI to the UE 100. For example, the control unit 230 can send the DCI to the UE 100 when the information included in the System Information Block Type 1 message is changed.

[0157] For example, the control unit 120 of UE 100 attempts to decode the PDCCH using P-RNTI. When the P-RNTI configured for UE 100 is equal to the P-RNTI scrambled into the CRC added to the DCI transmitted from base station 200, UE 100 is able to decode the PDCCH. Therefore, the control unit 120 can normally receive the DCI, i.e., the short message.

[0158] Control unit 120 determines the change cycle (i.e., when the DCI is received) based on the receipt of the short message. Figure 11 The next change cycle (i.e., the first change cycle) Figure 11 In the second change cycle, the control unit 120 of UE100 attempts to obtain updated system information. After the boundary between the first and second change cycles, the control unit 120 of UE100 attempts to obtain updated system information.

[0159] Step S203: The transmitting unit 211 of base station 200 transmits updated system information. The receiving unit 112 of UE 100 receives the updated system information from base station 200. The updated system information can indicate changes in the PRACH timing cycle.

[0160] Step S204: The transmitting unit 211 of the base station 200 transmits a specific DCI. The receiving unit 112 of the UE 100 receives the specific DCI from the base station 200.

[0161] Furthermore, a specific DCI may include priority information. The control unit 120 may prioritize the priority information included in a specific DCI over priority information included in other messages and / or predefined rules.

[0162] The control unit 120 of UE 100 receives updated system information and specific DCI from base station 200, and can therefore perform the processing of step S205.

[0163] In at least one of the following cases, the control unit 120 may perform the processing of step S205.

[0164] • The timing of receiving a specific DCI is the same as the timing of receiving a DCI including an SMS message, or within a predetermined time from that timing. • The timing of receiving a specific DCI coincides with the timing of the boundary of the change period for receiving the specific DCI (i.e., the end of the change period), or occurs within a predetermined time from that timing. • The timing of receiving a specific DCI coincides with the timing of obtaining updated system information, or occurs within a predetermined time from that timing. • The timing of receiving a specific DCI coincides with the timing of changing the PRACH timing based on updated system information (e.g., applying a changed RA configuration) or occurs within a predetermined time from that timing. • The timing of changing the PRACH timing based on a specific DCI (e.g., applying a changed RA configuration) (hereinafter sometimes referred to as the change timing based on a specific DCI) is the same as or within a predetermined time from the timing of receiving the DCI including the short message. • The timing of a change based on a specific DCI coincides with the timing of the boundary of the change cycle for that specific DCI (i.e., the end of the change cycle) or occurs within a predetermined time from that timing. • The timing of changes based on a specific DCI coincides with the timing of obtaining updated system information, or occurs within a predetermined timeframe from that timing. • The timing of changes based on a specific DCI coincides with or is within a predetermined timeframe from that timing when PRACH is changed based on updated system information (e.g., applying the changed RA configuration). Furthermore, the receiving unit 112 of the UE 100 can receive information indicating a predetermined time value from the base station 200. The control unit 120 of the UE 100 can determine whether to execute the processing of step S205 based on a timer set with a predetermined time value based on this information.

[0165] Additionally, the control unit 120 may ignore a specific DCI in at least one of the following cases. In this case, the control unit 120 may skip the processing of step S205.

[0166] • The boundary at which the timing of receiving a specific DCI message that is later than the update of the system information begins (hereinafter sometimes referred to as the boundary of the change cycle). • Cases where changes based on a specific DCI are scheduled later than the boundary of the change cycle. Ignoring specific DCIs, the control unit 120 applies configurations based on the acquired updated system information.

[0167] Furthermore, when ignoring a specific DCI, the control unit 120 can ignore specific information within a specific field included in the specific DCI. The control unit 120 can perform control based on information outside the specific field included in the specific DCI.

[0168] Step S205: The control unit 120 performs a priority determination. Specifically, the control unit 120 determines which piece of information, updated system information or control information (i.e., a specific DCI), takes priority. The control unit 120 may determine this based on at least one of the following methods.

[0169] In the first method, the control unit 120 determines, according to pre-defined rules, which information in a specific DCI should be prioritized between the updated system information and the information in the DCI.

[0170] The control unit 120 stores predefined rules. These predefined rules may be, for example, rules described in 3GPP technical specification documents. For example, the predefined rules may prioritize updated system information over a specific DCI, or they may prevent updated system information from taking precedence over a specific DCI.

[0171] If it is stipulated that updated system information takes precedence over a specific DCI, the control unit 120 determines that the updated system information takes precedence over the specific DCI. On the other hand, if it is stipulated that updated system information does not take precedence over a specific DCI, the control unit 120 determines that the specific DCI takes precedence over the updated system information.

[0172] Furthermore, if no priority information is received from base station 200, control unit 120 can perform priority determination based on the first method. If priority information is received from base station 200, control unit 120 can perform priority determination based on the following second method. Therefore, control unit 120 can prioritize the determination result of the second method over the determination result of the first method.

[0173] In the second method, the control unit 120 determines, based on priority information, which information in a specific DCI should be prioritized over the updated system information.

[0174] If the priority information indicates that updated system information takes precedence over a specific DCI, the control unit 120 determines that the updated system information takes precedence over the specific DCI. On the other hand, if the priority information indicates that updated system information does not take precedence over a specific DCI, the control unit 120 determines that the specific DCI takes precedence over the updated system information.

[0175] Furthermore, if the presence or absence of priority information in a field where priority information can be set within the information received from base station 200 indicates that updated system information takes precedence over a specific DCI, control unit 120 determines that the updated system information takes precedence over the specific DCI. Conversely, if the presence or absence of priority information in a field where priority information can be set within the information received from base station 200 indicates that updated system information does not take precedence over a specific DCI, control unit 120 determines that the specific DCI takes precedence over the updated system information.

[0176] In the third method, the control unit 120 determines, based on the timing of receiving a specific DCI, which information in the specific DCI should be prioritized: the updated system information. For example, the control unit 120 may perform the following determination.

[0177] (a1) When a specific DCI is received before receiving a DCI including a short message, the control unit 120 may determine to prioritize the specific DCI. (b1) When a specific DCI is received after receiving a DCI including a short message and before reaching the boundary of the change period in which the DCI was received, the control unit 120 may determine to prioritize the specific DCI. (c1) When a specific DCI is received after the boundary of the change cycle of receiving a DCI including a short message has been reached and before the updated system information is obtained, the control unit 120 may determine to prioritize the specific DCI. (d1) When a specific DCI is received after the updated system information has been obtained, the control unit 120 may determine to prioritize the updated system information. (e1) When a specific DCI is received after a certain period of time has elapsed since the updated system information was obtained, the control unit 120 can determine to prioritize the specific DCI. The receiving unit 112 of the UE 100 can receive information indicating a value for a certain period of time from the base station 200. The control unit 120 of the UE 100 can determine whether to execute the processing of step S205 based on a timer set with a value for a certain period of time based on the information.

[0178] Furthermore, when performing the determinations in (a1) to (c1) above, for example, the control unit 120 may apply a RA configuration based on a specific DCI until updated system information is obtained. If updated system information is obtained, the control unit 120 may apply a RA configuration based on that updated system information.

[0179] If no priority information is received from base station 200, control unit 120 may perform priority determination based on a third method. Control unit 120 may prioritize the determination result of the second method over the determination result of the third method.

[0180] In the fourth method, the control unit 120 determines which piece of information in the specific DCI takes priority: the updated system information or the information in the specific DCI, based on the timing of the PRACH change period (e.g., applying the changed RA configuration) based on the specific DCI. For example, the control unit 120 may perform the following determination.

[0181] (a2) When the timing changes to a specific DCI before receiving a DCI including a short message, the control unit 120 may determine to prioritize the specific DCI. (b2) When the timing of a change based on a specific DCI changes after receiving a DCI including a short message and before reaching the boundary of the change period for receiving the DCI, the control unit 120 determines to prioritize the specific DCI. (c2) When the timing of a change based on a specific DCI changes after reaching the boundary of the change period for receiving a DCI including a short message, but before obtaining updated system information, the control unit 120 may determine to prioritize the specific DCI. Alternatively, when the timing of a change based on a specific DCI changes after reaching the boundary of the change period for receiving a DCI including a short message, but before obtaining updated system information, the control unit 120 may determine to prioritize the updated system information. (d2) When the updated system information is obtained and the timing of the change becomes based on a specific DCI, the control unit 120 can determine to prioritize the updated system information. (e2) When a certain period of time has elapsed since the acquisition of the updated system information, and the timing changes to a specific DCI, the control unit 120 can determine to prioritize the specific DCI. The receiving unit 112 of the UE 100 can receive information indicating a certain period of time from the base station 200.

[0182] Furthermore, when performing the determinations described in (a2) to (c2) above, for example, the control unit 120 may apply a RA configuration based on a specific DCI until updated system information is obtained. If updated system information is obtained, the control unit 120 may apply a RA configuration based on that updated system information.

[0183] If no priority information is received from base station 200, control unit 120 may perform priority determination based on the fourth method. Control unit 120 may prioritize the determination result of the second method over the determination result of the fourth method.

[0184] In the fifth method, the control unit 120 determines which piece of information in a specific DCI should take priority, the updated system information or the updated system information, based on the content of the updated system information. Specifically, the control unit 120 may determine which piece of information should take priority based on whether the information regarding the period used to configure PRACH timing has been updated.

[0185] For example, if the information regarding the period used to configure PRACH timing is updated—that is, if the updated system information indicates a change in the period of the PRACH timing configured for UE 100—the control unit 120 may determine to prioritize the updated system information. For example, if the RA configuration specified (indicated) by the updated system information differs from the RA configuration already configured for UE 100, the control unit 120 may determine to prioritize the updated system information.

[0186] On the other hand, for example, if the information for configuring the PRACH timing period is not updated, that is, if the updated system information does not indicate a change in the PRACH timing period configured for UE 100, the control unit 120 may determine to prioritize a specific DCI.

[0187] Furthermore, even when it is determined that a specific DCI should be prioritized, the control unit 120 applies updated system information other than the information on the cycle for changing the PRACH timing.

[0188] Step S206: The control unit 120 determines the PRACH timing based on the prioritized information. Therefore, the control unit 120 can change the cycle of the PRACH timing.

[0189] When prioritizing updated system information, the control unit 120 determines the PRACH timing based on the updated system information. For example, the control unit 120 changes the RA configuration included in the updated system information. The control unit 120 determines the PRACH timing based on the changed RA configuration. Thus, the control unit 120 changes the PRACH timing cycle.

[0190] On the other hand, when prioritizing a specific DCI, the control unit 120 determines the PRACH timing based on the specific DCI. The control unit 120 can determine the PRACH timing and its period, similar to the first action example. Therefore, the control unit 120 changes the period of the PRACH timing.

[0191] Step S207: Similar to step S106, the transmitting unit 111 of UE 100 performs PRACH transmission at the determined PRACH timing. The receiving unit 212 of base station 200 receives PRACH from UE 100.

[0192] As described above, the receiving unit 112 of UE 100 receives updated system information and control information (i.e., specific DCI) from base station 200. The updated system information indicates a change in the PRACH timing period, and the control information is information indicating a change in the PRACH timing period and is carried by lower-layer signaling below the RRC layer. The control unit 120, according to priority information received from base station 200 or predefined rules, prioritizes one of the updated system information and specific DCI information, and changes the PRACH period based on this priority information. Therefore, when performing PRACH transmission, UE 100 can appropriately determine which change should be applied to the PRACH transmission according to the priority information received from base station 200 or predefined rules. The applicable change can be shared between UE 100 and base station 200 (cell), suppressing PRACH transmission / reception failures. As a result, dynamic adaptation can be appropriately performed.

[0193] Furthermore, the transmitting unit 211 of base station 200 sends updated system information and a specific DCI to UE 100. The updated system information indicates a change in the PRACH timing period, and the specific DCI is information indicating the change in the PRACH timing period and is carried by lower-layer signaling below the RRC layer. The transmitting unit 211 sends priority information to UE 100, which is used by UE 100 to determine which information in the updated system information or the specific DCI takes precedence. Thus, similarly to the above, the applicable changes can be shared between UE 100 and base station 200 (cell), and PRACH transmission / reception failures can be suppressed.

[0194] Additionally, priority information can indicate that updated system information takes precedence over a specific DCI. Since system information typically includes basic configurations in communications with base station 200, prioritizing updated system information can help suppress failures in communications between UE100 and base station 200.

[0195] In addition, the updated system information can include priority information. Therefore, UE 100 can obtain priority information even when it is not in an RRC connection state.

[0196] Furthermore, a specific DCI can include priority information. Therefore, since the specific DCI is carried by lower-layer signaling, priority information can be delivered to UE 100 faster than higher-layer signaling. As a result, network 10 can flexibly control the priority determination of UE 100.

[0197] Additionally, the receiving unit 112 can receive specific RRC messages addressed to the UE 100 from the base station 200. These specific RRC messages may include priority information. Therefore, the network 10 can modify the content of the priority information for each UE 100. As a result, the network 10 can flexibly control the priority determination of the UE 100.

[0198] Furthermore, the control unit 120 can prioritize updated system information according to a rule that prioritizes specific DCIs. Therefore, the UE 100 can make a determination even when there is no signaling related to priority information between the UE 100 and the base station 200, thus saving radio resources.

[0199] Furthermore, if the timing of changing the PRACH timing period based on a specific DCI is later than the boundary where the transmission of updated system information begins, the control unit 120 can ignore the specific DCI. Therefore, when updated system information is required, the UE 100 can reliably apply the updated system information.

[0200] Furthermore, when receiving updated system information that does not indicate a change in the PRACH timing period configured for UE 100, the control unit changes the PRACH timing period based on a specific DCI. Therefore, even without changing the PRACH timing period via system information, the network 10 can specifically change the PRACH timing period for UE 100.

[0201] (Other implementation methods) In the above embodiment, the control unit 120 of UE 100 determines whether a cell supports dynamic adaptation based on support information, but is not limited thereto. For example, the control unit 120 may determine whether a cell supports dynamic adaptation based on DA configuration information. For example, if the DA configuration information is included in system information (e.g., SIB 1 message), the control unit 120 may determine that the cell supports dynamic adaptation. On the other hand, if the DA configuration information is not included in the system information, the control unit 120 may determine that the cell does not support dynamic adaptation.

[0202] When the control unit 230 of base station 200 supports dynamic adaptation in its cell, it may include DA configuration information in the system information. The transmission unit 211 of base station 200 may then transmit system information including the DA configuration information in that cell. Conversely, when the control unit 230 does not support dynamic adaptation in its cell, it may omit the DA configuration information from the system information. The transmission unit 211 of base station 200 may then transmit system information excluding the DA configuration information in that cell.

[0203] In the above implementation, the PRACH timing period is changed dynamically, but not limited to this. For example, other parameters related to PRACH transmission can be changed by dynamically adapting the RA configuration without changing the PRACH timing period. That is, UE 100 can change anything other than the PRACH timing period through lower-layer signaling.

[0204] In the above embodiments, the example described is the case where a valid time period is configured in the modified RA configuration, but it is not limited to this. A valid time period may also not be configured. Base station 200 can control UE 100 to change the PRACH timing period or RA configuration via a specific DCI, regardless of the valid time period (i.e., whether or not a valid time period is configured). UE 100 can change the PRACH timing period or RA configuration via a specific DCI received from base station 200, regardless of the valid time period (i.e., whether or not a valid time period is configured).

[0205] In the above implementation, it is obvious that the order of the steps can be changed. For example, the processing of step S203 can be performed after step S204.

[0206] In the above implementation, the "change" of the RA configuration or the period of PRACH timing can be replaced with "update". Furthermore, the "period" of PRACH timing can be referred to as a "time period".

[0207] In the above embodiments, mobile communication system 1 is described as an example of an NR-based mobile communication system. However, mobile communication system 1 is not limited to this example. Mobile communication system 1 can be a TS system conforming to any other generation of systems (e.g., 6th generation) compliant with LTE (Long Term Evolution) or 3GPP standards. Base station 200 can be, for example, an eNB providing E-UTRA user plane and control plane protocol termination for UE 100 in LTE. Mobile communication system 1 can also be a TS system conforming to standards other than 3GPP standards. Base station 200 can be an IAB (Integrated Access and Backhaul) host or IAB node.

[0208] In the above embodiments, mobile communication system 1 has been described as an example of an NR-based mobile communication system. However, mobile communication system 1 is not limited to this example. Mobile communication system 1 can be a TS system of any other generation system (e.g., 6th generation) conforming to LTE or 3GPP standards. Base station 200 can be, for example, an eNB providing E-UTRA user plane and control plane protocol termination for UE 100 in LTE. Mobile communication system 1 can also be a TS system conforming to standards other than 3GPP standards.

[0209] The steps in the operations described in the above embodiments do not necessarily have to be executed in chronological order as shown in the flowchart or sequence diagram. For example, the steps in the operations may be executed in an order different from that shown in the flowchart or sequence diagram, or they may be executed in parallel. In addition, a part of a step in the operation may be deleted, or further steps may be added to the process. Furthermore, the above-described operation flows are not limited to being implemented independently, and two or more operation flows may be combined for implementation. For example, a part of a step in one operation flow may be added to another operation flow, or a part of a step in one operation flow may be replaced by a part of a step in another operation flow.

[0210] Programs may also be provided to enable a computer to perform the various processes performed by the UE 100 or the base station 200. The programs may be recorded on a computer-readable medium. Using a computer-readable medium, programs can be installed on the computer. Here, the computer-readable medium on which the programs are recorded may also be a non-transient recording medium. There are no particular limitations on the non-transient recording medium, but it may be, for example, a CD-ROM (Compact Disk Read Only Memory) or DVD-ROM (Digital Versatile Disc Read Only Memory). Alternatively, the circuitry for performing the various processes performed by the UE 100 or the base station 200 may be integrated, and at least a portion of the UE 100 or the base station 200 may be configured as a semiconductor integrated circuit (chipset, SoC (System on Chip)).

[0211] In the above embodiments, "transmit" can refer to performing processing at least one layer within a protocol stack for transmission, or it can refer to physically transmitting a signal wirelessly or via a wired connection. Alternatively, "transmit" can also refer to a combination of performing the aforementioned processing at least one layer and physically transmitting a signal wirelessly or via a wired connection. Similarly, "receive" can refer to performing processing at least one layer within a protocol stack for reception, or it can refer to physically receiving a signal wirelessly or via a wired connection. Alternatively, "receive" can refer to a combination of performing the aforementioned processing at least one layer and physically receiving a signal wirelessly or via a wired connection. Similarly, "obtain / acquire" can refer to obtaining information from stored information, obtaining information from information received from other nodes, or obtaining information by generating information. Similarly, unless otherwise explicitly stated, the descriptions "based on" and "depending on / in response to" do not mean "only based on" or "only in response to". The description "based on" means "only based on" and "at least partially based on". Similarly, the phrase "responding to" refers to both "responding only to" and "responding at least partially to". Likewise, "include" and "comprise" do not mean only including the listed items, but rather that they may include only the listed items or other items in addition to the listed items. Likewise, in this disclosure, "or" does not refer to logical XOR, but rather to logical OR. Furthermore, any reference to elements using terms such as "first," "second," etc., as used in this disclosure does not generally limit the quantity or order of these elements. These terms may be used in this disclosure as a convenient way to distinguish between two or more elements. Therefore, reference to a first element and a second element does not mean that only two elements can be used therein, or that the first element must precede the second element in some form. In this disclosure, for example, where articles such as "a," "an," and "the" are added through translation, these articles may include multiple articles unless the context explicitly indicates that multiple articles are not included.

[0212] It is understood that although this disclosure has been described with reference to embodiments, this disclosure is not limited to those embodiments or constructions. This disclosure also includes various modifications and equivalent variations. In addition, various combinations, methods, and further combinations and methods that include only one element, more or fewer elements therein also fall within the scope and spirit of this disclosure.

[0213] (Postscript) Features related to the above embodiments are noted.

[0214] (Postscript 1) A communication device, comprising: The receiving unit receives updated system information and control information from the base station. The updated system information indicates changes in the period of the Physical Random Access Channel (PRACH) timing, and the control information is information indicating changes in the period of the PRACH timing and is carried by signaling at a lower layer than the Radio Resource Control (RRC) layer. The control unit, in accordance with the priority information received from the aforementioned base station or a pre-defined rule, prioritizes one of the aforementioned updated system information and the aforementioned control information, and changes the period of the aforementioned PRACH based on the aforementioned priority information.

[0215] (Postscript 2) According to the communication device described in Appendix 1, the aforementioned priority information indicates that the aforementioned updated system information takes precedence over the aforementioned control information.

[0216] (Note 3) According to the communication device described in Appendix 1 or 2, the aforementioned updated system information includes the aforementioned priority information.

[0217] (Postscript 4) According to any one of the appendices 1 to 3, the aforementioned control information includes the aforementioned priority information.

[0218] (Note 5) According to any one of Appendices 1 to 4, in the communication device, the aforementioned receiving unit receives a specific RRC message addressed to the aforementioned communication device from the aforementioned base station. The aforementioned specific RRC message includes the aforementioned priority information.

[0219] (Note 6) According to any one of Appendix 1 to 5, in the communication device, the aforementioned control unit prioritizes the aforementioned updated system information over the aforementioned control information in accordance with the aforementioned rule that instructs the aforementioned updated system information to take precedence over the aforementioned control information.

[0220] (Note 7) According to any one of Appendices 1 to 6, if the timing of changing the period of the aforementioned PRACH timing based on the aforementioned control information is later than the boundary at which the transmission of the aforementioned updated system information is started, the aforementioned control unit ignores the aforementioned control information.

[0221] (Postscript 8) According to any one of Appendices 1 to 7, when the communication device receives updated system information that does not indicate a change in the period of the aforementioned PRACH timing configured for the aforementioned communication device, the aforementioned control unit changes the period of the aforementioned PRACH based on the aforementioned control information.

[0222] (Note 9) A type of base station, This includes a transmitting unit that sends updated system information and control information to the communication equipment. The updated system information changes the period of the Physical Random Access Channel (PRACH) timing, and the control information changes the period of the PRACH timing and is carried by signaling at a lower layer below the Radio Resource Control (RRC) layer. The aforementioned transmitting unit sends priority information to the aforementioned communication device, and the aforementioned priority information is used by the aforementioned communication device to determine which piece of information, the aforementioned updated system information or the aforementioned control information, takes precedence.

[0223] (Postscript 10) A communication method, executed by a communication device, comprising: The steps of receiving updated system information and control information from the base station, wherein the updated system information indicates a change in the period of the Physical Random Access Channel (PRACH) timing, and the control information is information indicating the change in the period of the PRACH timing and is carried by signaling at a lower layer below the Radio Resource Control (RRC) layer; and The steps include prioritizing one of the aforementioned updated system information and the aforementioned control information according to the priority information received from the aforementioned base station or the pre-defined rules, and changing the period of the aforementioned PRACH based on the aforementioned priority information.

Claims

1. A communication device (100), comprising: The receiving unit (112) receives updated system information and control information from the base station (200). The updated system information indicates a change in the period of the Physical Random Access Channel (PRACH) timing, and the control information is information indicating the change in the period of the PRACH timing and is carried by signaling at a lower layer below the Radio Resource Control (RRC) layer. as well as The control unit (120) prioritizes one of the updated system information and control information according to priority information received from the base station or a pre-defined rule, and changes the period of the PRACH based on the priority information.

2. The communication device according to claim 1, wherein the priority information indicates that the updated system information takes precedence over the control information.

3. The communication device according to claim 1 or 2, wherein the updated system information includes the priority information.

4. The communication device according to claim 1 or 2, wherein the control information includes the priority information.

5. The communication device according to claim 1 or 2, wherein the receiving unit receives a specific RRC message destined for the communication device from the base station. The specific RRC message includes the priority information.

6. The communication device according to claim 1, wherein the control unit prioritizes the updated system information according to the rule that instructs the updated system information to take precedence over the control information.

7. In the communication device according to claim 1 or 2, if the timing of changing the period of the PRACH timing based on the control information is later than the boundary at which the transmission of the updated system information is started, the control unit ignores the control information.

8. In the communication device according to claim 1 or 2, when receiving updated system information that does not indicate a change in the period of the PRACH timing configured for the communication device, the control unit changes the period of the PRACH based on the control information.

9. A base station (200), The system includes a transmitting unit (211) that sends updated system information and control information to the communication device (100). The updated system information changes the period of the Physical Random Access Channel (PRACH) timing, and the control information is information that changes the period of the PRACH timing and is carried by signaling at a lower layer below the Radio Resource Control (RRC) layer. The transmitting unit sends priority information to the communication device, and the priority information is used by the communication device to determine which information in the updated system information or the control information should take precedence.

10. A communication method performed by a communication device (100), the communication method comprising: The steps of receiving updated system information and control information from the base station (200), wherein the updated system information indicates a change in the period of the Physical Random Access Channel (PRACH) timing, and the control information is information indicating the change in the period of the PRACH timing and is carried by signaling at a lower layer below the Radio Resource Control (RRC) layer; as well as The step of prioritizing one of the updated system information and the control information according to priority information received from the base station or a predefined rule, and changing the period of the PRACH based on the priority information.

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